· your design ideas are quickly captured using the ulticap schematic design tool. ulticap uses...

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EL7ECITVILV'TITHE INTERNATIONAL

ELECTRONICS MAGAZINE

May 1994f, 2.45

DIFFERENTIAL PROBEFOR OSCILLOSCOPESMorsedecoder

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Your design ideas are quicklycaptured using the ULTIcapschematic design Tool. ULTIcapuses REAL-TIME checks to preventlogic errors. Schematic editing ispainless; simply click your start andend points and ULTIcapautomatically wires them for you.ULTIcap's auto snap to pin and autojunction features ensure your netlistis complete, thereby relieving you oftedious netlist checking.

ULTIshell, the integrated userinterface, makes sure all your designinformation is transferred correctlyfrom ULTIcap to ULTlboard. Goodmanual placement tools are vital tothe progress of your design,therefore ULTlboard gives you apowerful suite of REAL-TIMEfunctions such as, FORCE VECTORS,RATS NEST RECONNECT andDENSITY HISTOGRAMS. Pin andgate swapping allows you to furtheroptimise your layout.

Now you can quickly route yourcritical tracks. ULTlboard'sREAL-TIME DESIGN RULE CHECKwill not allow you to make illegalconnections or violate your designrules. ULTlboard's powerful TRACESHOVE, andREROUTE -WHILE -MOVE algorithmsguarantee that any manual trackediting is flawless. Blind and buriedvias and surface mount designs arefully supported.

If you need partial ground planes,then with the Dos extended boardsystems you can automaticallycreate copper polygons simply bydrawing the outline. The polygon isthen filled with copper of thedesired net, all correct pins areconnected to the polygon withthermal relief connections and userdefined gaps are respected aroundall other pads and tracks.

NamMEEK

ULTlboard's autorouter allows youto control which parts of your boardare autorouted, either selectednets, or a component, or a windowof the board, or the whole board.ULTlboard's intelligent router usescopper sharing techniques tominimise route lengths. Automaticvia minimisation reduces thenumber of vias to decreaseproduction costs. The autorouterwill handle up to 32 layers, as wellas single sided routing.

ULTlboard's backannotationautomatically updates your ULTIcap

schematic with any pin and gateI swaps or component renumbering.

Finally, your design is postprocessed to generate pen /photo plots, dot matrix/laser orpostscript prints and customdrill files.

ULTlboard, one of the leading PC baseddesign systems, is suplied worldwide via anetwork of ULTImate Technology officesand distributors. ULTlboard's success inthe professional design community isprimarily due to its superior interactivefunctionality.

Real Time Placement Aids, Real TimeDesign Rule Check, Trace Reroute WhileMove and Trace shove, are all featureswich will dramatically reduce your designtime.

Intergration with ULTIcap guaranteessmooth data flow between Schematic andPCB editing and the inclusion of third partynetlist interfaces ensures ULTlboard will fitinto any design environment.

Another of ULTImate Technology'sstrengths is our flexible growth path.Users may start with a low cost ULTlboardChallenger Lite and grow, step by step, toa 32 -bit Advanced system with Ripup andRetry Autorouting and Digital Simulation.

ULTImate Technonlogy also looks afterexisting users, providing they have validmainenance subscriptions they will beupgraded to a new system based on theiroriginal investment. For instance, a 1987ULTlboard-DOSsystem has now been

upgraded to a 32 -bitAdvaced system withWindows compliance and 2Autorouters.

ULTImate Technology notonly adds value to yourinvestment in a ULTlboardsystem but backs it upwith the highest qualitysupport from ourdistributors and offices.

Corporate Headquarters:Energiestraat 3ff 1411 AT NaardenThe Netherlandstel.:1+3112159 - 44444fax:1+3112159 - 43345

UK/Ireland Sales -Office:2 Bacchus House Calleva ParkAldermaston Berkshire RG7 412Wtel.: 0734 - 812030 fax: 0734 - 815323

ULTIcap Schematics -8, ULTlboard PCB -Design DOS -Version with 500 Pin Design capacity 100% Compatible with 32 -bit Versions 450 page manual PLUS full color tutorial Technical Support, Updates possible 'Growth path' to 32 -bit without loss of investment

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Also available is a full function (as described above, with a 350 pin design capacity)Evaluation System for only f 75 excl shipping/handling, VAT/Sales).

ELEKTINELECTRONICS

CONTENTSMay 1994Volume 20Number 222ISSN 0268/4519

In next month's issue

800535 SBC extension

boardI2C bus boosterRS485 interface

Heat sinks - how andwhen to use them

The IL300 linearoptoisolatorRC active filtersIntelligent EPROM eraser

Fuel consumptionmonitor for injection

enginesand more for your

continued interest

Front coverThe photograph shows thedifferential probe describedon page 22 being used toascertain the waveformacross an incandescent lightbulb. The probe overcomesseveral shortcomings of theprobe supplied with manyoscilloscopes. It is a10:1/100:1 design thatenables floatingmeasurements to be carriedout. It is suitable formeasuring high voltages.

© 1994 Elektuur By.

ABCAL Dri lit RE U OF U IONS

CONSUMER PRESS

BOOK CREDIT VOUCHER. In this and the next issue we will publisha voucher that will entitle the holder to up to 30% discount on thepurchase price of any Elektor Electronics book - page 67

Low -voltage CMOS devicesBy our Editorial Staff

SS I I

33 COURSE: 800535 hardware/assembler - Part 3Software by Dr. M. Ohsmann

38 PROJECT: Stamp BASIC computerSources: Parallel Inc. USA & K.H. Eichler

GENERAL INTEREST

10 PROJECT Mains signalling system - Part 2Design by W Hacklander and S Furchtbar

28 PROJECT General purpose sensor monitorDesign by M Haas

42 COURSE Figuring it out - Part 16 Mote about FourierBy Owen Bishop

62 PROJECT: TV sound -to -light unitFrom an idea by B. Willaert

I I :

16 PROJECT Morse decoderDesign by Velleman NV

52 Using the double balanced mixerBy Joseph J Carr. BSc, MSEE

22 PROJECT Differential probe for oscilloscopesDesign by H Bonekamp

46 PROJECT Low -voltage monitorDesign by J. Ruiters

74 Buyers' guide69 Component ratings7 Credits

74 Index of advertisers69 Letters50 New books68 Product/Industry news70 Readers' services67 Switchboard72 Terms of Business

'

Low -voltage CMOS devices - p. 5

Mains signalling system -p.10

Morse decoder - p. 16

Stamp BASIC computer - p. 38

Elektor Electronics is published monthly, except in August, by Elektor Electronics (Publishing), P.O. Box 1414, Dorchester, Dorset DT2 8YH, England. The magazine isavailable from newsagents, bookshops, and electronics retail outlets, or on subscription at an annual (1994) post paid price of £27-00 in the United Kingdom; air speeded: £3400in Europe; £43.00 in Africa, the Middle East and South America; £4500 in Australia, New Zealand and the Far East; and $57.00 in the USA and Canada. Second Class Postagepaid at Rahway N.J. Postmaster: please send address corrections to Elektor Electronics, c/o Mercury Airfreight International Ltd Inc., 2323 Randolph Avenue, Avenel, NewJersey, N.J. 07001.

ELEKTOR ELECTRONICS MAY 1994

4 Please mention ELEKTOR ELECTRONICS when contacting advertisers

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ACCESS, MASTERCARD, VISA Welcome.


One sector of the electronicsmarket continues to demand

faster and more powerful per-sonal computers. Another de-mands a longer life from one bat-tery charge in case of portablecomputers: 2-3 hours is now aminimum. Such demands arenot restricted to computers: theyapply equally to portable radio re-ceivers, radio telephones and in-strumentation equipment. Atthe same time, the world needsa more efficient use of energy.These conflicting demands forcedesigners of electronic compo-nents to bring out ever faster,smaller and more energy -friendlydevices. A logical consequenceof this is that ICs are becomingsmaller and smaller. This in turnmeans that their dissipation be-comes a problem.

All these requirements haveresulted in a lowering of the tra-ditional 5-V supply voltage to3.3V (JEDEC standard for mains -operated equipment). Low -volt-age versions of 80386 and 680x0processors, memories, ASICs,disc controllers, LCD controllers,data converters and regulatorsare already available.

This article takes a closer lookat a number of low -voltage fam-ilies of CMOS logic devices fromPhilips. Each of these familieshas a unique product differen-tiator. LV-HCMOS is a 3.3 V medium -

speed CMOS family that iscompatible with LS andHCMOS.

LVC is a 3.3 V CMOS logicfamily that is compatible withFAST, ACL, ( Q)FACT and ALS.

HLL is the world's fastestCMOS family with centresupply pinning and provid-

130120

110

100

908070605040302010

0

Relative speed (%)

LOW -VOLTAGECMOS DEVICES

By our editorial staff

ing low skew, low EMI and aspeed as FCT-C.

ALVC is basically the Multi-byteTM version of HLL.

LVT is a 3.3 V BiCMOS fam-ily that is optimized for drivingbackplanes and provides liveinsertion/auto three -state, bushold and outputs that can han-dle forced 5 V. It is compatiblewith ABT, BCT and F CT -A.

All devices in these families op-erate from supplies of 1.2-3.6 V.Because of their low dissipation,these devices are eminently suit-able for use in battery -operatedequipment. Moreover, in view oftheir high speed, they are also agood choice in fast digital cir-

cuits.Other advantages are that,

because of the low supply voltage,noise levels are down and the re-liability of the system increases(because of the lower mechanicalstresses in the ICs).

Wide voltage rangeAlthough JEDEC has stan-dardized the supply voltage formains -operated equipment at3.3 V±0.3 V, this does not applyto battery -operated equipment.The problem there is the large vari-ation of the battery voltage overthe life of the battery. For in-stance, the e.m.f. oftwo series -con -

Relative power (%)

Speed

Power

2 3 4

130120

110

100

90807060

5040302010

05 6

Supply Voltage (V)

940023-11

Fig. 1. Relation between supply voltage, speed and dissipation of logic components.

nected alkaline or carbon -zincbatteries at the end of their lifeis 1.8 V, while that of a NiCd bat-tery is 1.2 V to just before it is fullydischarged. Thanks to the widerange of operating voltages ofthe new devices, the use of dry aswell as rechargeable batteriespresents no problems.

Low voltage, samespeedAs shown in Fig. 1, the speed ofa logic component and the supplyvoltage from which it operates arerelated. The dynamic power dis-sipation (the static dissipationof CMOS devices is virtually nil)decreases roughly with the squareof a reduction in supply voltage.Thus, an obvious method of re-ducing the dissipation of thesecircuits is a decrease of the nop-minal supply voltage. The rele-vant graph in Fig. 1 shows thatthe dissipation of a 3.3-V com-ponent is about 65% lower thanthat of a 5-V component, but isaccompanied by a 20% reductionin speed. Thus, the immediate ad-vantages of moving from 5-V to3.3-V operation are that thespeed/dissipation ratio is morethan doubled, and it becomespossible to power CMOS logicfrom a 1 -cell or 2 -cell battery inportable equipment. The reduc-tion of maximum speed may benegated, and even reversed, bythe use of sub -micron technology.

LV-HCMOS family

The LV-CMOS logic family is basedon HCMOS (HC) technology andis manufactured in a similar man-ner. Although developed primarilyfor operation from 3.3 V supplies,the components in this familycan work with supply voltagesranging from 1.0 V to 3.6 V.

With a 3.3 V supply, the speedand performance are the same asHCMOS working from 5 V. Thereare, therefore, no disadvantagesin replacing 5 V logic componentswith LV-HCMOS devices.

To obtain the same speed asavailable from 5-V CMOS com-ponents, the channel length ofLV-HCMOS devices is reducedto 2 pm, the gate oxide is thinnerand the threshold voltages are low-ered. Because of the reduced chan-nel length, the propagation delaywith a supply of 3.3 V is only 9 ns.With a supply voltage of 2 V, theoutput drive is 4 mA and even 6 mAfor driver outputs. With a 3.3 Vsupply, outputs can drive loads

130 a


6 COMPONENTS

LVC familyThe LVC family is compatiblewith the F(ast) CMOS series asfar as speed, output drive char-acteristics and pinning are con-cerned. It is manufactured in6 um CMOS technology and thusdissipates much less power thanF(ast) logic devices. Althoughdesigned for operation from a3.3 V ±0.3 V supply, the devicescan be used with a supply volt-age range of 1.2 V to 3.6V, but theytend to slow down at the lower volt-ages. With a supply of 2 V, theyprovide a drive of up to 24 mA.With a 3.3 V supply, outputs candrive loads 50 S2. Because ofthe sub -micron technology(0.6 um), the propagation delaywith a supply of 3.3 V is not greaterthan 6.5 ns. Since, with a supplyof 3.3 V, the input levels may beas high as 5.5 V, this family is ide-ally suitable for use in 5 V to 3 Vand 3 V to 5 V level shifting inmixed 3 V/5 V systems.

HLL family

The HLL family is a new logic fam-ily: the world's fastest 3.3 V logicICs. The devices are manufac-tured in sub -micron (0.6 pm)CMOS technology that uses two -level metal and epitaxial sub-strates. HLL ICs operating from3.3 V ±0.3 V work at twice the speedof F(ast) bipolar logic. Since theyare CMOS devices, they dissi-pate only a fraction of the powerneeded by bipolar components.The family is ideally suited for veryhigh speed operation in data busesof mains -powered equipment.The sub -micron technology guar-antees a propagation delay of notmore than 4 ns with a 3.3 V supply.The high dynamic output driveallows transition times to be muchshorter than the propagationdelay. Outputs can drive loads

50 51. With a 3.3 V supply, thedevices interface directly withTTL logic.

too,"3

2

10 20 30 40 50

vcc (v)

940023-12

Fig. 2. Propagation delay vssupply voltage characteristic.

Speed line (log)

940023 15

Fig. 3. Each logic family has its own operating area.

Key parameter/feature LV-HCMOS I LVC HLUALVC LVT

Key parametersNomenclature* 74LVxxxX 74LVCxxxX 74HLL33xxxX

74ALVC16xxxX74LVTxxxX

Supply voltage range V 1.0 to 3.6 1.2 to 3.6 1.2 to 3.6 2.7 to 3.6

Output current lailoL mA 6/6 24/24 24/24 32/64

Quiescent current PA 80 20 80/40 80

Typical propagation delay:data to output nsoutput -enable to output ns

9

144.05.8

2.14.0

2.43.6

Max. ground bounce (V0,) V 0.5 0.8 1.0 0.8

Temperature range °C -40 to +125 -40 to +85 -40 to +85 -40 to +85

FeaturesFull CMOSAdvanced BiCMOS

V V

Drive capability:13512501235

Effective channel length:2.0µm0.8 pm0.6µm

Corner supply pinsCentre supply pins V

TTL level inputTTL level output5 V input capabilityForced 5 V outputLive insertionInput bus hold

V V

40*

V

4-

V

Packages:DILSOSSOPTSSOP

V

V

V

V V

Application:glue logicbattery -powered equipmentlocal bussuper RPbackplane

V V V

V

V

Compatible 5 V families LS-TTLHC/HCTN74xx

FASTACU(Q)FACT

ALS

FCT-C ABTBC/BCTFCT-A

Product differentiator 3 V equivalent ofLS/HC

3 V equivalent ofFAST

world's fastestlogic

3 V equivalent ofABT; optimizedfor backplanes

xxx = 245 etc, X = package code: D = SO, DB = SSOP II, PW = TSSOP I, DL=SSOP 48-56, DGG=TSSOP48-56

" For transceivers VIN = Vcc + 0.5 V.

Table 1. Main parameters of the low -voltage CMOS logic families.


Produced and published byELEKTORELECTRONICS (Publishing)

Editor/publisher Len SeymourTechnical Editor: J. finning

Editorial & Administrative O®cesP.O. Box 1414DORCHESTER DT2 SYHEnglandTelephone: (0305) 250 995 (National )Or +44 305 250 995 (International )Fax' (0305) 250 996 (National )or +44 305 250 996 (international)

U.K. Advertising Office:3 Crescent TerraceCHELTENHAM GL50 3PETelephone: (0242) 510 760Fax (0242) 226 626

International Advertising Office:Elektuur B VPO Box 756190 AB BEEKThe NetherlandsTelephone' +31 46 38 94 44Fax: +31 46 37 01 61

Subscriptions:World Wide Subscription Service Ltd.

LVT familyThe low -voltage BiCMOS logicfamily is manufactured in 0.8 pmQUBiC technology to combinethe best properties of CMOS with

5 V system

Unit 4, Gibbs Reed FarmPashley RoadTICEHURST TN5 7HETelephone: (0580) 200 657 (Nattonal)or +44 580 200 657 (international)Fax (0580) 200 616 (National)or +44 580200 616 (International)

Head OfficeP.O. Box 756190AB BEEKThe NetherlandsTelephone. +3146 389444Telex 56617 (elekt ol)Fax +31 46 37 01 61Managing Director. M.M J Landman

Distribution.SEYMOUR1270 London RoadLONDON SW16 4DII

Printed m the Netherlands by NDB,Zocterwoude

Overseas editions:FRANCEElektor sarlLes Trois TilleulsB.P 59; 59850 NIEPPEEditor. G.C.P. Raedersdorf

the best of bipolar devices. Thisresults in very high output cur-rent and very high speed withoutcompromise of dissipation or noiselevels. The outputs can deliver cur -

5/V

leveltranslator

3.3 V system

LV-HCMOS

+3.3 V

LV-HCMOS

LV-HCMOS

940023-13

GERMANYElektor Verlag GmbHStlsterfeld Stra& 255100 AACHENEditor-. El A. Krempelsauer

GREECEElektor EPEKariskaki 1416673 Voula-ATHENAEditor; E. Xanthouls

HUNGARYElektor Elektromkal folydrst

1015 BudapestHanby/Any u,13Editor Lakatos Andros

INDIAElektor Electronics PVT LtdChhotani Building52C, Proctor Road, Grant Road (E)BOMBAY 400 007Editor: C.R. Chandaraus

ISRAELElektorcalPO Box 41096TEL AVIV 61410Publisher: M. Avraham

rents of up to 32 mA and sinkcurrents of up to 64 mA. Theycan drive loads 35 S1 directly. TheQUBiC technology guaranteespropagation delays of not greater

800

700

P (mW)

600

500

400

300

200

100

0o

NETHERLANDSElektunrI3VPeter Treckpoelstrast 2-46191 VK BEEKEditor: P.E.L. Kersemakit

POLANDElektor Elektroufit02-777 Warszawa 130Skrytka Pocztowa 271Editor W Marciniak

PORTUGALFerreira & Bento Lda.

R D Esterani, 32-1°1000 LISBOAEditor: F. Ferreira& Al

SPAINResistor Electronic a AplicadaCalle Mendes 15 Entlo C.28003 MADRIDEditor: Agustin Gonzales Buelta

SWEDENElectronic Press ABBox 550514105 HUDDINGEEditor Bill Cedrum

than 4 ns with a supply of 3.3 V.The devices may be used in mixed3 V/5 V systems.

END

3.6 V

1.2 V

20 40 60 80 100

frequency (MHz)

940023-14

Fig. 4. Various methods of linking traditional 5-V logic devicesand low -voltage logic devices.


Fig. 5. Dissipation vs frequency characteristics of the variouslogic families.


; t' 741

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9338 VICOM G FAX 081-552 0946

74H0574 0.647460589 1.647400590 0.9474H0592 1.197400593 1.667400595 0.927460597 0387400620 1.6274H0623 1.627400633 1.62

74007243 0.7674007244 0.5774607245 0.5274607251 0.8674007253 0.5174007257 0.5474007258 0.7274007259 0.7874001273 0.6874007280 0.98

74F14 04174F20 0.2874F27 0.2874F30 0.2874F32 0.2874F37 0.4174F38 0.4474F40 0.6674F51 0.4474F64 0.32

74A0251 0607400253 0607400258 0.607400273 1.107400283 1.407400299 2.067400373 0.947400374 0.927400377 0.987400540 0.98

78012 04878515 0.557905 0.287905A 0.32790560 0.607909 0E57912 0.307912A 0.367912FA 0.787915 0.30

a 9A/200VDIL 0.383.0A/200V SIL 0.5760/100V SIL 1.60BA/2000 SIL 1.9635A/100V Sqr 2.9866001002 1.64KBP03502 2.98W005- 1A/50V0.32WO2G- 1,511 0.40

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DIGITAL INTEGRATED CIRCUIT SPECIALIST 7400640 1.327400643 1.32

74007283 0.9074007297 0.82

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7400541 0.9874A0573 1.38

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STATIC RAM7400645 1.40 74001299 1.64 74686 0.41 7400574 1.38 791_120 0.35 2K0820R/SIL 0.70 4,43152,6,8,9.83047460646 1.77 74007354 1.26 74F109 0.58 7400646 POA 7901200P 0.35 88001500/Sq 035 10,12,15,16,

4000 SERIES 45136 2045148 1.12

401667 0.43401767 0.78

74160 0.9474161A 0.98

7405169 0.597400170 POA

7400669 077400670 078

7400648 1.777460651 1.47

74007356 1 28'74007365 0.54

74F112 0.72746113 1.30

7400648 POA 79M05 0 42'

79M05A 04268001500SIL 0 60SK86008/60A POA

18432 19 6608' ' ' '

20, 24, 25 & 30MHz

2114-30 3.4062640P-10 2.406264LP-12 2.4040000 0.16

4000UB 0.1845156 1.1245168 044

40188T 0.78402067 0.95

74163 1.2874164 1,20

7400173 0.39741_51730 0.44

7405673 POA741_5674 17.60

7460652 1.477460658 4.49

74607366 0.8074007367 0.54

746114 1.30746125 0.60

74C SERIES 79M05F0 0.6579M12 0.50 CRYSTALS

Price: £3.52 e8. 62256LP-12 4.9

400IA 0.1640016 018

4517B 1.8445188 0.40

4021ST 0654023BT 038

74165 1.5774166 106

7400174 0367400175 034

7400682 2.627405683 POA

74HC659 4.497400664 4.49

74001368 0.8074607373 0.44

746126 0.98746132 0.58

74(00 0.5674002 0.56

79M12A OBO

0M3171 0.50 HC49( C18/U)30, 32, 32/68,33.33, 40 & 50MHz

62256LP-10 4.9CDM6116AE3 5.30

400186 0.2240026 0.181.84320045198 0.3645206 0.36

402467 076402567 038

74174 1.5374175 1.23

741_5181 1.827400162 2.05

7400684 3.85741_5685 POA

7400665 4.4974110670 1.10

74007374 0.5574007377 0.64

746138 0.58746139 0.58

74008 0.5674010 0.56

LM317MP 1 06.

LM31702 0.55

Freq.MHz1.60 "0' £4.45 ''''

CDM6117AE3 5.8HM1-6116-5 4.3

4006B 039 45218 a72 402787 0.45 74180 129 7405183 2.05 7405686 POA 7400677 378 74001390 068 74F148 0.94 74014 0.56 LM338K 4.45 2.000000 1,66 programmable HM3-6116-5 3.60

400708 0.2040086 0A0

45228 0.8645266 0.50

402867 0.564029BT OB6

74184 POA74185 1.76

74L5189 2.607400190 0.49

7400687 POA7400688 1.98

7400678 5.91

7400680 3.8374007393 0.6874001394 0.00

746151 0.58746153 0.62

74020 a9874030 098

A7BGU U1C 1.02UA79GU1C 1.02

2.457600 1.49

3.276900 II"Crystal

Oscillators

HM61160P-2 2.60HM61160P-3 2.6

4009AE 023400908 0.29

45276 0,560.49

4040131 0.78404267 074

74191 1.4174192 1.41

74L5191 0.4974L0192 049

74L0693 POA74LS794 POA

7460682 4.21 74007423 0.62 746157 0.58 74032 0.68 R04195N 1.60 3.579545 1.10 HM6117LP-3 570M62256LP-10 7.9 3

40108 02940118 0.18501186 0.1840120E 0.16

4528845296 0E745306 1.9245318 1.1445326 0.44

404667 1.41

404767 1.06404967 1,06405067 0.48

74193 1.6574221 1.2374259 29274265 1.46

7400193 0487405194 05474001940 05774001950 0E7

7400795 POA7400796 POA7400797 POA7405848 POA

7460684 5.707460688 0.877400690 1.627460691 1.627400692 1.73

74007533 1.4474607534 07574007540 0.6474007541 0.6474007563 0.98

746158 0.70746160 1.107461600 1.10746161 1.1074F162 1.28

74042 2.8874048 2.9874073 1.2874074 0.9474076 1.26

DIODES 4.000000 1.0022

4096000 1.104.194304 .1

1. 0,4.433619 1. '''

EXO-3C SERIESspin DIL Plastic

PackageFreq.= MHz12, 14.31818, 16,

HM6264ALP-12 3.9HM6264ASP-20 3.9HM6267P-35 5.07HM6281280P-80

1a5

1N2986RB 18.201N3881 2.541N39970 6.5540128 0.20

4013B 0.2040148 0.42

4534E1 2.824536B 122

4051BT 078405267 a 84

74273 POA74276 3.56

138

7400196 0.687405197 0.687400221 0.44

74HC SERIES 7490693 1.7374H0696 1.48

74007564 0.7874007573 0.64

746163 128746164 1.28

74085 1.8674090 1.29

I N4001 0.04'0,14002 0.04

4.6080004.915200 11210°

5,000000/0 1.0220MHz

16384,136608 & HM662040-12 15.8KM62256A0P-10 4.9749000 0.19

40156 0.4240166 0.24

45388 0.604539B 0.6245418 0.52

4053BT 098406067 0844066BT 059

7427974283 12674298 POA

7400224 20247400240 0.42

740002 0.19740003 0.24

7490697 1.247400698 124

74007574 0.6474001583 0.00

746166 4.3274F168 4.48

74093 2.1074095 1.60

1N4003 0.04164006 0.04

5.068800 .105.242880 11,

Price: £3.92 ea. 005164D -10L 24P2114AL-2 3.40

40170 03840188 0.3840198 0.2640200E 03640208 0.3840218 040

4543B 0.5745448 2.11

45478 1.6845496 POA45518 1.6245538 2.37

4068137 0.3840690131 0384070137 038407161 038407501 0.38407761 0.38

74365 07074367 1.0674393 2.9474403 POA74423 POA

7405241 0.42741_5242 0.427400243 0.4274LS244 0.427400245 0.4274L0247 0.44

740004 0.197400004 0.24740005 020740008 0.20740010 029740011 0.20

7400699 1.2474004002 0.3574004015 1.0774004016 0A474H04017 0.4274904020 09274004022 0.56

74007597 1.5274001640 13474H01643 1.3474007645 1.11

74007646 2.4074001648 19074007651 1.64

746169 3.6074F174 0.7674F175 0.76746181 4.48746182 1.8074F189 4.9874F190 3.40

740150 5.40740151 3.94740154 5.82740/57 3.60740164 2.54740165 2.54

164007 0.041N4148 0.031N4149 0061N4150 0.081N4446 0061N4728A 0.24

5.888200 1.26.000000 1.

6.144000 I (. )22

6.400000 1.64°

6.552000 1.

6.553600 1 4°

16pIn DIL PlasticPackage

Programmable for57 Diff.Frequency

SPG8640AN0.005 to 600kHz

P2114AL-4 a 4PCD5101P 3.30UPD43256AGU100

8.38P0432560-12 5.6UPD4364C-15 4.7

40228 0.4040238 0.20402308 02340240E 0.2740248 0.3240258 0.1940260 0.5440278 03040288 0.3840296 03940306 02140310 1.0440328 070

45546 B0145558 0.4845560 0.4945576 1.8845588 2.1845606 1.51

45618 1/44562B 5.1545666 1.1045688 5.1745696 3.044572UB 0.7045806

407881 0.38408167 0.38409387 0.454094BT 0.954508BT 2.054510135 1.02451167 1.3545128T 0.68451467 2.20451681 1.024518B1 1.18452067 1.18452167 107

74LS SERIES 7400248 0.68

7400251 0.327400253 a447400256 a 787400257 03474052570 0A67400258 0.4474002580 0.487405259 0.487400260 02274L0266 0.32741_0273 0.42

740014 0.2574HC14A 034740020 0.22746021 0.2274HC27 0.2274HC30 0.22740032 0.22740042 0.48746051 029740058 0.42740073 0.34740074 025740075 0.40HN2701024HG10

74004024 0.5074004028 0.5874004040 0.5074904046 1.5474004049 04874004050 ass74004051 06474004052 0.6874004053 0.6874110405301.1074004060 0A774004061 252

74007652 0.0074007670 1.1074007673 1.6474007688 1.10740014002 0.39740074015 1,13740074016 0.52740074017 068740014020 074740074024 OB8740074040 070740074046 2.10

74F191 3.2074F192 3.20746193 3.20746194 1.48746195 2.24746219 4.3874F224 POA746240 0.62746241 0.62746244 062746245 0.72746251 0.62

740221 298740240 2.08740244 2.08740373 2.0874C374 2.08740901 1.18740902 1.18740903 1.52740906 1.10740907 1.10740908 2.20740911 14.42740912 1442

1N47350 0241N47360 0241N47400 0.241N4743A 0241N4744A 0241N4756A 0.241N52266 0.091N523213 009161523451 0.091653370 0.4819534913 0A81N535213 0.481N53576 0.48

7.372800 0.2781

1.008.867230 1.

9.830400 1.3240

1aocr000 1,

10.69500 1 1°11.00000 1.91°0

12.00000 0.

13.87500 2 9214.00000 1146°4

14.31818/S 01..8105

14.74560/514 74560 1 10

SPG8640BN0.0083 to 1MHz

SPG86400N0.064 to 768kHz

SPG8650BN0.00083 to 100kHz

p..10,r 0 9.25 88.

UVPROMS

270128-25 3.9270640-15 3.95270256-15 3.90270256-25 3.90027256 5.4C2705120-12 6.4627010000-12 8.922704096-12 POPHM27C101G-20 9.8C

74L000 0.18740501 0.18740002 0.18740003 0.18740004 021740005 0.21

740506 0E1740007 0.51740508 0.1874L009 0.18740010 0.18

40339 0.9r5403413 1 10

40358 03940368 257

458013 a 8445818 18545828 3.8545836 0.86

452287 1.22452881 0a84534BD POA453881 105

740011 0.18740012 0.18740013 0.19740014 0.24

7400275 POA74L0279 0.337400280 0.8674L5283 0.45

740076 0.4074HC77 0.517461085 0.48740086 028

74604066 0.467400406600.5474H04067 47274004072 0.45

74HC14051 a96740014052 0.96740014053 0.84740074059 2.24

7462510 0.66746253 0.6274F257 0.627462570 0.66

740914 1.16740915 2.74740922 6.8074C923 6.80

1N53656 0.481 N5366B 0.481 N5370B 0.481 N5380B 0.48

15.00000/S 1.1016.00000 1 0216.00000/S 1,2010432100/S 1.10

Conveners 16.63HN27C64FP-201 3.40HN27C64G-15 4,20HN27C64G-20 4.2C

TDK CE -0344 5.603WSR 15-15 27.50

40376 127

0184039B 3.2240408 042

458484584E1 0.5745850 0494597CP 6.9045988 6.90

4541 BT 1.05454381 1.02455561 POA455667 1.05

740015 0.38740020 0.18740021 0.18740522 0.18

7400290 0.48741_5292 16.8674LS293 0.387400294 17.82

740C93 0.447400107 03974001090 035740112 040

74H04075 0a274004078 0.4674004094 0.6474604316 0.68

740014060 a84740074066 0.66740074067 4.93740074075 0.36

746258 0.6274F259 POA746260 0.78746269 7A8

740925 9.30740926 9.30740929 9.30

1N5401 0.111N5402 0.111962870 1.551N825 1,80

19.66080/5 1.2020.00000 S 1 6022.11840/S

.

24.00000/0 118682

IPL 5.010 23.40

1 Watt DC/DC5V input tOutput

06462532P 4.50004827128G-25 A50HN482764G 3.8C

M2716 -1F1 35074S SERIES4041B 0.41

4041UB 0.3245990 95047209 POA

4585BT 0.954010601 0.53

740024 0.58740026 018

7400295 1.1174LS295A 1.15

7400113 a407400123 040

74004351 0.8974004511 0.55

749014094 0.8474H014316 0.68

74F273 0.84746280 0.68

168250 1.34110827 1.40

2764800/0 1 203a00000/0 6.99.

DIL & SIL by

Newr.MM512732K 4.4CM51.27641( 3.3074000 0.44

40428 0.32 4720V POA 40244BT 1.35 74LS27 0.18 7400298 098 7400125 0A0 74004514 1.38 740074351 1.04 74F283 092 74002 0.44 100252 0.20 32 .00000/S 1.40NMA0505,5V MBM27084-20/21V

40436 0.36 4723B P00 4037367 234 740028 024 7405299 1.53 7400126 a47 74004515 1.42 740074510 1.54 74F299 POA 74$ 0. 5082-2800 066 4800000/5 1.68NMA0509x9V 4.90

40440 0.36 47248 190 74L530 018 7400321 182 740C131 0.52 740C4518 080 740014511 0.94 746323 POA 74004 042 5082-2810 1.40 s Series NMA0512,12V MBM270128-30 4.204045B 0.94 4701,, 9.80 740031 1.58 7400322 P00 7400132 0.32 74HC4520 072 74HC14514 1.64 746350 1.50 74008 0.42 5082-2835 0.44 NMA0515x15V MBM270256-30 91C40466 0.42 4737VP 18.28 740032 0.20 74LS322A POA 74H0133 0.32 74004534 0.00 740074515 250 74F352 0.64 74009 0.48 M119 0.60 HC33/U Price:07.90e8. NMC27C2560-254047B 038 4738VP 18.50 7400 0.36 74L033 020 7400323 3.24 7400137 0.76 74HC4538 0.68 74HC14516 1.61 746353 .14 74010 0.98 M144 072 4.940486 0.82 4750VD 28.50 7401 0.30 740037 018 7405347 286 74H0138 0.34 74004543 0.81 740014520 0.90 746365 1.28 74011 0.48 M215 0.58 a204800 8.23 DC/DC Converters NMC270640-25 3.6E40498 024 4752VP 29.25 7402 0.34 740038 0.18 7400348 1.98 7400139 a31 74007001 1.01 740014538 1.02 746366 1.30 74020 0.48 AAZI 7 058 0.307200 6.99 by Computer TMS2519.1L-45 4.5404958 0.28 4753VP POA 7403 0.34 740540 0.18 7400352 1.68 74H0141 0.61 74H07002 1.01 7400T7007 039 74F367 1.48 74032 0.78 AAZ18 0.48 1.000000 3.95 Pro40.18 TM527128J0-25 4.604050B a22 4754VP P00 7404 040 740542 032 7400353 198 74HC147 0.61 74H07032 1.01 740C17046 2.80 746368 1.30 74040 025 60510 0.08 1.843200 3.71 PM623 24.90 TMS2716JL-45 46040516 0.34 40085 1.98 7405 040 740044 2.11 7405363 2.10 74100148 0.55 74007266 0.84 740C-140102 2.43 74F373 0.62 74051 0.36 BAV45 4.98 2.000000 4.65 PM671 26.70 UPD27256D/21V 5.6C40528 0.33 40097 092 7406 0.68 740047 0.55 7400364 POA 7400151 0.40 74H07074 1.99 7400140103 1.48 74F374 0.62 74064 0.36 000062 0.06 2.097152 3.71 PM672 26.70 0P027320/21V 4.95

40930 0.34 40098 0.62 74060 072 74L548 094 74L0365 0.30 74H0153 0.40 74HC7292 1.10 74HC140104 271 74F377 092 74074 098 60216 0.06 2.457600 1.92 PM903 44.00 0P027C2560-15 E8C40548 0.68 40100 2.46 7407 0.63 740049 1.38 74003650 034 7400154 0.98 74H04010 1.10 7400140105 1.82 74F381 1.56 1.12 0.32 2500000 192 PM951 46'50 UPD27C512D-1540558 0.6240568 0.48

40101 POA 74070 0.650.37

740051 0.190.19

7400366 03674LS366A 0.42

74100155 0.697400157 0.42

740040102 1.10740040103 1.10 74HC SERIES

SURFACE

746381 36874F385 POA

740112 '1,08745124 242

00212BB04

2 248804050 0.22

3.500000 2'25 RESISTORS4956.

UPD27C64D-25 .9

40590 2.9840102 1.2040103 0.88

74087409 0 67

740554740055 0a2 7405367 0.29 7400158 0.47 741-1C40105 140

MOUNT746395 P00746399 0.98

740132 0.98 86809 0.60HC49/U4H

METAL FILM EEPROMS40606 03840638 0.42

40105 1.8240106 0.30

7410 0.357412 0.64

74LS73 0.4074LS73A 0.48

74003670 0347400368 0.36

7400160 0.647460161 042 74HCT SERIES 74HCOOM 0.32 746412 P00

740133 0.73740134 1.95

05179 042B5260-200 358

3.276800 1B6 0.25W 1%E24 Series 28064-25 9.8C

40666 027 40107 0.42 7413 0.76 740574 022 74003680 172 7400162 0.64 74HCO2M 0.32 746413 POA 740138 0.88 131261-200 3.9 8 5.068800 2.25a 579545 1.58

10R tel 1M 3p each 28064-15 1a97400700 0.2240675 1.95 40108 POA 7414 0.72 74LS74A 0.24 74LS373 0.38 7400163 0.42 746003M 0.32 746432 POA 740139 0.88 BYV28-100 a9 9 7. 864320 N.B. Min Oty. Order 280256-20 25.84

40688 0.20 40109 1.24 7416 0.53 740075 0.28 741_0374 0.44 7460164 a 42 74110102 022 74HC04M 0.32 746521 1.20 740140 07 8 YVB32-50 1.601.49

8000000 114 Min. 5pcs per value 280256-15 27.50406908 0.2140708 0.2140718 0.20

40110 1.0440114 2.6240116 12.48

7417 0.487420 0.377425 0.59

740576 0.68741_5760 0.72741_077 0.42

7400375 0.427400377 096741_0378 0.98

7400165 0.557400166 0887400173 076

740C103 0267400104 0.227400108 0.227400710 0.22

7400004 0327411008M 0.3274HC1OM 0.32740014M 0.36

746524 P00746533 1.20746534 1.20746537 1.60

740153 1.26740157 1/2740163 2 60

058805 0.6005160 0.40MV1404 15. 9°

10.00000 2.2511.05920 2.40

1 200000 1.14

METAL FILMPRECISION

280256-1500 28.5C

X281600 5.1002816AP-25 5.1C

407213 0 20 40117 1.80 7426 0 48 740078 0.32 7400379 0.99 7400174 42a74100111 0.22 74HC2OM 0.36 746538 1.60

740174 0.92 MV209 1,20 . 00000 2.25 0.25 WATT 0.1% X28640P-35 12.21114

40738 0.20

40756 0.1940147 1.23 7427 0.59 741_083 0.39 74003810 4.96 7400175 036

74HC181 1.94 7400114 a26 7410030M a36 746539 1.60740175 135740182 329

00200 0 1000202 0.20

1600000 1 .14 090 Serie. 24001 1.6224CO2 2.10

40768 0.4240770 0.20

40160 0.5440161 0.5440162 0.54

7430 0.357432 0.457437 059

74LS83A 0.39741_085 0.38740086 0.27

741-S385 3.48741_0386 0987400390 0.46

7400182 ass7400190 0.67

7400120 0.2674H0121 026

740032M 0367400740 0.36

746540 1.98746541 138

740189 2.14740195 240

0047 0.140090 0.14

2000000 1.02

24.000Do 1.90

100Rce: 10 25

eac5KPri £0.94 h 24004 2.924016 5.4C

40785 021 40163 0.54 7438 0.49 74L090 0.40 74L0393 0.40 7400191 052 7400127 0.26 7461075M a34 746543 3.98 740240 100 P6KE36A 0.98 UM -1 HIGH PRECISION 280040-20 4.4C4081B 0.18 40174 0.34 7440 077 740091 POA 741_0395 0.66 7400192 0.77 7460730 0.26 740085WM 055 746544 POA 745241 1.12 P6KE47A 0.88 NON -INDUCTIVE 59011 1.4440828 020 40175 0.47 7442 0.55 74LS92 POA 74053950 0.94 7400193 0.54 74100132 0.22 74HC86M 0.36 746545 POA 740244 177 REC53A 0.40 8.000000 2.25 WIRE WOUND 93006 1.1240850 038 40181 P00 7445 1.20 741_S93 0.44 7400396 P00 7400194 0.67 7460742 0.46 7400123AM 046 746547 POA 740257 1.22 ZPD2.7V 006 8.192000 2.02 0.15 WATT 0.1% 93046 1.240866 0.3840896 0.98

40192 06240193 074

7446 1937447 0.98

740095 04874L096 0.82

7400398 POA74025874LS399 0.01

7400195 0A77400221 0.44

7400773 0.3674HC174 0 26

'

7400125M 0.4674HC132M 0.4274HC138M 0.38

74F573 292746574 2 92

.

1.22740260 0.70 ZENER DIODES

I a00000 2.251100000 225 Temp.Coe11.3ppm MISC. MEMORIES

40930 024 40194 1.82 7447A 1.67 74LS107 0.28 7400423 0.98 74HC237 0.73 7400775 0.36 746579 7.98 74$273 2.44 MISC. 12.28800 2.66 10R,50R,1000,250R,40940 038 40195 2.24 7451 0.57 74LS107A 0.38 74LS445 P00 7400238 064 7400785 0.60 7400139M 0.38 746604 A84 74S274 2.42 15.00000 225 10K.100K 6341-1J 4.5

40950 070 40240 2.62 7454 0.72 7400109 0.28 7400450 10.68 740C240 0.44 7400786 0.36 74HC154WM 0.64 746620 POA 740280 096 BZY93C7V52.66 17.73447 2.801

Price £3.85 each AM2148-45DC 5.4440960 1.10 40244 1.36 7470 0.54 74001090 032 74054614 7,16 7400241 044 7460793 0.58 7460157M 0.38 746621 POA 745283 1.90 BZY93C15 2.66 18.00000 2.50 AM27S281PC 3.9

40970 2.75 40245 1.36 7472 0.38 7400112 028 7400465 182 74H0242 74007107 040 74HC161M 0.48 74F646 740374 2.18 2.66 20.00000 225 HIGH PRECISION 10171300A-10OP40988 a40 40257 0.54 7473 0.59 741_51120 0.34 7400467 7.78 740C243 0.88 74HC1109 0.42 7400164M 048 746646 915 740394 2.10

07593020BZY018R

93 296 21.00000 2.25 NON -INDUCTIVE POP4099B 0.42 40373 1.10 7474 0.53 7405113 032 7413468 7.78 7400244 0.43 74007112 0.42 74140165M 0.57

7460173M 0.48746676 POA 740412 2.10 BZY93024V 296 24.00000 2.80 WIRE WOUND 10171320A -100P

4104P 101 40374 1 10 7475 0.67 741_5113A 0.38 74L5469 6.10 7400245 0.44 74007123 0.64 746821 745436 2.62 8ZY93C33R 2.66 0.33 WATT 0.1% POP4160B 0.8545026 4A2 7476 0.72 7400114 0.32 74004690 6.70 7400251 0.35 74007125 0.56 7400174M 0.38 746823 POA 745437 2.62 K7030120 0.40 CRYSTALS MISC. M684145 A94161B 0.85 45027 5.99 7480 1.26 74051140 ass 74L0490 285 7400253 0.52 74007126 0.56 7460221AM 0.65

7400240WM746825 POA 740472 a32 BZX61C9V20.09 Temp,00e1f 3ppm MCM4027003 2.8C

4174B 127 45028 4A9 7483 1.10 7400122 0.39 74004910 12.82 7400257 0.47 74007132 0,50 0.55 746827 4.48 740734 262 BZX61024V 0.09 FIC43/1 1R,5R,10R,20R,50R N82S126AN 2441750 1.14 45040 POA 7485 0.58 7400123 036 7400502 POA 7400258 0.73 74607137 0.52 74HC244WM 0.55 746841 4.48 ZENER DIODES 1:°°00°° 9.99 Price: £3.80 each N8201530 5.8C

VOLTAGE41949 .1 A' 45041 P00 7486 0.53 7403125 0.28 7405540 0.80 74110259 0.65 74FICT138 0.32 740C245AW 0.62 746843 4.93 400mW N820181AN 60c4409P 11.05 45100 POA 7490 0.76 74001250 0.32 7400541 0.80 74HC266 0.36 74HC1139 0.45

740011477400251M 04274HC259M 0.69

746845 P00 REGULATORS 2.45 to 755 MINI CYLINDER100R ,120R, 2500" NMC6504J-9 3.40

4410P 16.454411P 21.584412FP POA

45106 79845109 POA45138 POA

7490A 1.347491 2.567492 0.67

7400126 03274LS126A 0.367400132 0.29

74L0569 POA7405573 1.347400574 1.34

7400273 0.5474H0279 0.51740C280 0.89

068740011151 05274HCT153 0.44

741-10273WM 0.5574HC367WM 0.53

7461244 37578008AP 1.1

7805 0.28

Price: 6p each

ZENER DIODES

0.032768 0.88

WATCH

5006,/K, 2K, 5K,10K,20KPrice: £3.10 each

NMC9306N 1AP5101 L-1 3.9C

76P18S030N 1.774AC SERIES

4412FL P004412VP POA4416P POA

45145 1a0445146 POA45151 19.50

7492A 1.127493 06874930 0.70

74L5133 0.18741-0136 0.3874L0137 0.98

7400590 4 857400592 5.287400593 679

7400283 0587400298 0.737400299 1.09

74007154 1.2474607157 04474HC1158 048

740C373WM 0.55741-10374WM 0.5574HC390M 0.57

7805A a327805FA 0457806 0.28

500mW2.4V to 2005Price. 6p each

0.032768 0.82

CRYSTALOSC. MODULES

TBP24010N 2,90

76P2450106 a 1

TC5501P as

740000 038740002 0.49

MEMORIES

DYNAMIC RAM4419P POA4429PB P00

45152 21.4545156 15.80

74950 1.107497 5.23

7400138 0317409139 0.34

7400595 4.857400597 4.95

7400323 19874HC354 0.55

741001160 05674HC1161 0.56

74HC393M 0.53741-10540WM 076

740004 0.40740008 0A0

7808 0.287809 032

ZENER DIODES1055040P-2 a 4C705516P0-15 42C

'

8pin DIL

4433P P00 45157 14.38 74104 067 741_3145 0.66 74L0621 POA 7400356 0.65 74607162 0.84 7400541WM 0.76 740010 040 7812 0.281.3 WATT

Plastic pkg 4164-10 140 7C5517AP-2 A2C4443P POA4447P P00

45158 11.9445159 POA

74107 0,6074110 POA

7400147 2.867400148 0.83

7400622 POA7400623 2.98

7400365 0.417400366 0.52

74001163 05674007164 0.52

741-10573WM 1.097460574WM a 84

740C11 0.40740014 040

78120 0327812C70 032 2.7V to 200V

P riCe: each10p

TTL Output4 Pins spaced at

4164-12 1204164-15 1.20

705565PL-15 3.6C

TMS4014JDL 3.4C4468P POA 45406 2.73 74116 3.10 7400151 032 741-5624 2.10 7400367 0.47 740011165 0.52 7400688WM 0.84 740020 0A0 7815 0.28 corners of 8pinDIL 41256-8 2.40

4469P POA

4499P POA45407 6.4745411 P00

74118 POA74119 P00

7405153 0327413154 1.12

7405625 5.

74L0626 POA

7400368 0.527400373 0.44740(373

74007166 0E274007173 0.52

74004017M 0.4874004020M 048

740032 0.40740074 0.48

7818 0.287824 0.28 ZENER DIODES

WATT, req.= mH z

41256-10 2.4041256-12 2.40 CAPACITORS

4490P 3.204495P 9.27

45414 15.60 74121 0,98 7405155 034 7400627 P00 7400374 0.447400375 0.76

74007174 05274007175 052

741004040M 0.4474004046M 1,68

7400109 0.647400112 0.81

78005 0.2478L05A 028

3.07.5V to 270V

4, 4.9152, 8, 10,12, 16 & 20

41264-15 2.2441464-12 4.45

SURFACE MOUNT

4497P 13.5845428 POA

POA74123 09474125

7400156 0.387400157

7400628 1.787405629 741-10377 0.51 74007181 324 74004060M 048 7400138 0.65 78005ACLP0.40 Price:40p each Price. 12., 41464-10 4.45 Multilayer Ceramic

4499P 6.244500B 19.45

4543345440 POA45441 POA

0.6774126 09874128 1,19

0387413158 0.347405160 0.48

1.98741_5631 POA7400639 POA

7400386 0297400390 0.38

74007182 036741-107190 0.64

74004066W 0.8474004538M a 78

7400139 0.657400151 0.68

780050CZ 02878012 0.28

ZENER DIODES5.0 WATT

3.3V 200V24, 32, 40 &

4464-10 2.80414256A-70 330

63 VOLTCase Size: 1206

4501B a324502B 0.38

074132 86 74001600 0.54 7400640 09 874F7400393 0.417400423 0.64

74HC1191 0.6474001192 0.94

SERIES7400153 0.657400157 0.81

78L120 0.2878012ACZ 0.30

to

Price: 42p each50MHzPrice 13.40 ea.

44025607-10 B95440256-8 5.00

1-2.W1.25°V°

4000 SERIESSURFACE 74,004503B 0.38

74145 1.1674150 1.86

7405161 0.46741_5161A 0.49

741_5641 038741_5641-1 128 7400521 0.95 74007193 0.64 7400158 0.65 78015 0.28

ZENER DIODES511000-85 8.45 10pF 22pF 33pF

47064504E1 1.1245058 4.42

MOUNT 74151 0.8074151A 080

7405162 0A87400162A 1.07

7400642 a98100pF7405642-1 POA

7400533 ass7400534 0.89

74007194 1.1374E101195 1.16

7460274,4 028

7400163 0.807400169 1.987400174 0.65

78L24 02878056 1.10 STUD MOUNT

20 WATT

Spin DILSealed Metal

HM484160P-154.60

220pF 330pF470pF 100006 2200p1400167 0.32

45068 1.14 4002137 0.32 74153 0.90 7400163 0A2 7400643 POA 7400540 0.69 74007221 0.98 74606 78M05 0327.5V 75V

Package HM48416AP-204.25 3300pF 4700pF45060 1.14 401187 0.32 74154 2.16 741_0163A 0.47 741_0644 POA 7400541 ass 74007237 0.94 74607

47400175 0.80 78M050 0.35 to HCMOS Output HY53C256LS-80 10000,

450813 1.14 4011 UBT0.32740056374155 0.81 7405164 034 7405645 1.28 088 741001238 051 74608 7400191 1.38 78M12 0.32 Price, 14.94 ea. 1.60 22000pF 33000p64510B 05445118 0.44

4012131 0.32401387 0.45

74157 0.7474158 1.57

7400165 0.597405166 0.59

7400645-1 1.287405646 5.85

7400564 0.887400573 0.64

74H0724174007240 0.5574007241 0.

74610 0.2874611 0 8

7400240 0.927400241 092

78M12A 0.3678M130 0.65 BRIDGE

13.2mm sq.Pins spaced at

1-H530464LS-803.95

Price: 15p each

45128 0.38 4015137 084 74159 3.98 7400168 0.75 7405652 POA 7400573A 0.72 74007242 076 74613 0.627400244 0.927400245 1.10

78M15 0.3278005 0.48

RECTIFIERS corners of 8pinDIL HYB511000-85 8.45 4700006100000pFPrice: 18p each


Please mention ELEKTOR ELECTRONICS when contacting advertisers 9an 11071CP 164MICROPROCESSOR

& SUPPORT ICsHDI -0165-5 10.96HD146818AP 4.20HD3-6402-9 116HD3-6440-9 8.89HD3-6495-9 8.89H044883 a52H046505SP 9.85HD46802P 5.50HD6321P 420HD63485PS32 3250H063B03XP 11.95HD68000-8 11.59HD6845SP 6.92HD68852P 5.60HE/68E321P 4.29HI3-7159-5 20.98H13-71590-5 23.40HM10422 14.30

D82C86H 17.06M6402AIPL 1020M6402IPL 7.75M64031PL 10.80MS2600P-15 4 40NS8250N 7.80

SAB8155-P 3.82 TIL100SAB8259AP 159 TIL111SAB82054-2-P 412 TIL113SAB82055A-2-P 4.80 TIL117S0800451cc46413.60 TIL11900112661bc1n28 3.35 TIL311SCN266100428 135 TLP504APALI 6R4 -150N 298 TLP521-4G8TL16C552FN 12.58 TORXITMP7002NL-2 4.97 TOTX173TMP8085AP-2 5.98

1a8aso0.601851209.651.584.20

73 4.964.96

CL7611DCPA 112CL7621DCPA 1.98CL7622 POACL76500PD 4.98CL765000PD 6.27CL765200PD 824CL7652CPD 8.24CL7660CPA 1.40

CL7660SCPA 3.80CL7662CPA 4.40CL7663BCJA 6.78CL7663BCPA 5.10CL7664CPA 7.95CL7665ACPA 4.98CL7673CPA 1.38CL8052ACPD 8.730L8068AJD 11.38CL8069C000 3.750L8069D0SQ 2a8CL8069DCZR 2a8CL821I CPA 2a6CL82120PA a48CM7I 70IPG 6.420M7207AIPD 6.42

LM34015LM343H 8.80LM346N 3.96LM348DP 0.40LM348N 140LM3507 6.85LM351N 2.60LM358N 132LM359N 4.68LM36OH 7.72LM361 M/SMD 6A0LM363H-100 16.50LM369DN 3.82LM369DRC 3/0LM380N 1.20LM381AN 7.88LM385Z-1 .2 2.20LM385Z-2.5 2.20LM386M-1/SMD 1.65LM3.86N-1 1.40LM386N-3 1.80LM3866-4 260LM387AN 5.90LM388N-1 4.25

NE536H 4.90NE5530N 182NE5532AN 1.58NE5532N 180NE5534AN 1.80146555N 0.20NE556/SMD 0.70NE556N 0.38NE558N 2.28NE564N 3.42NE565N 2.94NE56711 0.65NE568N POANE570N 4.60NE571 N 3.40NE589N 4.25NE592/SMD 1.80NE592N 1.40NE592N14 0.92NE602AN 2a8NE602N 2.40NE604AN 8.24NE605N 8.60NE612AN 2.87

TL072ACP 1.48TL072CN 0.50TL072CP 150TL074ACN 2.85TL074CN 0a4TL081 CP 048TL082CP 0.48TL0840N 0.48TL27L2CO/SMD 1.98TL497ACN 3.44TL507CP 4.03TL7702ACP 204TL7705ACP 2.04

TL7705CP 2.04TL7709ACP 2.04TL7770-SC 312TL783060 5.10TLC22010P 3.74TLC2274CN 285TLC251CP a54TL026520P 4.92TLC2654CP 4.84TLC271CP 084

MEM111.11751,7 1.02751070 11275108 1.8075108A 1.847510, 2.0875109A 2.4675110A 1.3675113 3.0275114 3.0475115 la075116 3.30

75121 26075122 pop,75136 110751, 4.4075140 2.65751, 1.60751504 2.6575152 6.3675154 1.757515, 1,7575155 1.2075157 4.40

BC182 018BC182A 1088C1 82B 0.08BC182L 0.08B0182LB 0.08

0°133 0.08BC183C 0.08BC183L 0.08BC184 0.08001840 018BC184L 0.08BC184LC 0.08130212-18 0.08BC212A 018802128 0.0800212L 0.080021218 am00213 108BC213L 10860214 108BC214L 0.11007 0.080023923

11200307 018

BFW10 1.20BFX48 149136085 0.59BFX88 anBF089 1.59BFY50 1340FY52 134BFY90 0.92BS107 128BS170 038BS250 152BSR60 0.48130020 0.38BSX21 0.488SX61 1.8501136-600 1.10BUW46 494BUZ11 1.60BUZ11A 1.62BOZ47A 6.90IRFZ14 1.14IRF220 1.77J113 1392175 a65

100114DEC 7A010014100 9.806303XP 176

63263485GP32/1P

Irm 194'20

95

63B03XP 10.'076502 19865020 5.4065206 4 406522 4.4065220 5.266551 4436551A 4'4365002P2 5'846500263 6.9865010262 7100

6502262 4.80

65051E-1 80

65051E-2 4-3868000P-10 6.98680006-16 113.20

TMS3477NL 6 68TMS3700NSB 8.78TMS3702ANS 8/8 3630BM/BBTMS3835ANS 7.55 49620/BBTMS77C01 NL 10.74 555TMS9900NL 24.40 6341TMS9901 NL 14.16 741-OPAMPTMS9902ANL 15.94 00060705TMS99I4ANL 2110 AD520JNTMS9928ANL 7.40 AD524TMS9995JDL 69.85 AD534JHUA9636ACP 1.98 A°537.0A9637A 1.98 AD548JN

LINEAR & MISCS .

140POA

-TIMER 0.20

/4-1 P°A0.182.14POA

21.52POA

-IN POA

1'2268000P-8 6.50680086-8 85

'

NS82509 -0 7.80M5M82051AP 420

UA9638CP 1.98 AD578JN1.96 AD581JHUA9639CP75160APOA

8.92CM72071P0 6.42CM7209IPA 3.75

LM389N 3.40LM3900N 160

NJM4556D 1.20NJM4558DX 1.20

TLC272CP 1.30TLC274CN 240

75159 6255.95

130327 0.08BC328 0.08

J270 192JA101 OA868010P-12 POA

M5M82054P-6 5.40 UM68450 4.95 AD581KCSA/SMD9.97 CM7211AMIPL A68 LM3909N 2.64 OP070J 3.60 TLC3390N 1.98 75161A 6.47 00337 0.08 M80501 1.1068026 3.40MAB8031AH1 2P 4.56 UM9151 POA AD585A0 POA CM7211MIPL 4.68 LM3914N 440 OPO7CN 0.95 TLC372CP 1.40 75162A 7,59 60337-25 108 MJE13070 1.106803AP POA

6805E3E 1198 MAB8035HL-6P a98MC10103P 1.98

UM9151-3 POA75172N01J6B8238 POA

AD592CN POA00524A0 1264

M7212AMIPL 3 88M72131PD 4.58

LM393N 0.30119393P 0.30

060706 0.950PO7EP 3.10

TLC551CP 3.68TLC555CP 165

3.6875173 3.,

00489 0.2400490 0.30

MJE340 0.68MJE350 1.1068106 POA

6821P684019 3-40

MC10115L 121MCI 0115P 1.98

06082020 4.98UPB8284AD 4.9875174NGAD595A0 1120AD648JN 3.40

AD7°7IN 3A0

CM7216AIJI 22.44

CM7217AIPI 9.20LM394CN 5.98LM3999Z 2.76

OPI IGP S85OP177FP 171

TLC556CN 1.58TLC7524CN 5.24TLE2061CP

75174 3.203.66

80516 02200517 120

MJE520 0.80MP03638 118

172068446AD711JN6845P 4.86684556 5.40

MCI 46805E2P a18MC68000P12/16 POAMC68010P10/12 POAMC6802F' 2.47

UPE182860 4.98UPD70108C-10 9.10UPD701080-8 695751760UPD701160-10 1290

2.34AD712JN 3.72AD7245JN/KN POA

CM7217BIJI 10.42M72171J1 10.42

CM7218AIJI 6.85M7218AIPI 6.85

LM399H 7.85LM4250J 11.82LM5550N 0.28LMS65CN 7.48

OP27GP 2.89OP42FZ 7A4OP77GP 2.07060709 0.95

2.20TLE2062CP 3.40TLE2064CN 3.45TLE2I 61CP 2.42

75175 2a075I76A 160

2287517687 AN

BC546 0.05BC6A 10500546054

015130547 0.08

MPSA06 0.12MPSA13 112MPSA63 012MPSA92 0.2468A0OP POA

MC6809P 6.78 0PD701160-8 9.20M7218DUIAD74IKN 3.69 6.85 LM7100H 2.80 PM7548HP 1820 TMS3477NL 5.96 75177 2.60 005470 0.08 MP0005 2.21688096 4.30M06821P 1.80 UPD71055C 4.38 AD7523KN a 80 M7218E1JL 14.76 LM723CH 2a0 RC4136N 0.98 TP102406NE 7.14 75178 2.60 8054713 108 MTP8P08 2.80688216 198

6134.40P 2.5668A5OP 2.9868009P 3.98

MC6840P 5.05MC6844P 18.40MC6845P 7.38MC6850P 3.35

UPC/72018C 1168UP07201C 180UPD765AC 5A2M7226BIPLUPD765AC 5.42

AD7537J9 3298AD7537LN POA80754266 POAAD7543JCWE POA

M72241PL 8.98M7226AUL 26.12

23.54M7249IDM POA

LM723CN 0/0LM7330N 2.65LM741CJ-14 2.20LM7410N 0.45

904193N POARC4194N 2.85R042070N 1.92R04558 0.90

TPIC2802KV 8.40TPIC6259N 3.28TP1C6273N 328TP106595N 128

75182 a6075183 260751, 0 4075189 0735

BC5470 0.0800548 0.08BC548B 0.08130549 0 08

00147 1.800019 1.850045 0.650072 0.8068821P 1 98

68040P 1988080A ,496

808581-1-2 5'98

MC68705R3P 25.35MC68AOOP 7.02MC68809P 7.62

UPD780C-1 4.76UPD80C39HC 8.422.84UPD8155HD 5.84

AD7578K9 46.15A0844AN °73AD00804L0N 420ADC0820CCN 22A0

M7555I0A 2A0CM75551PA 0.84

M75561P0 1a5

LM747C9 240LM747CN 0.90LM78GCP 2.40

9C4558P 0.60REFO1CP 133REFOI HP 133

TSC426CPA POATSC500CPE POATSC7106CPL 6.81

75,94 pm7536175365 2.72

805498 018BC550 108BC550B 018

0078 180008118 18000817 0.92

8086 3 408086-2 3'90

MC8314P 6.60MCM6810P 3.00

UPD825I AFC A08UPD82530.2 132 ADC083400N 10.80

ADC804LCWM 12.10

M6403IPL 10.80L272 2.10

LM79GCP a 40LM833N 2.82

REFO2CP 198REFO3GP 169

TSC7116CPL 5.25TSC7126CPL 5.35

754374 3.26754508 164

005500 0.08BC556 0.08

PN3643 0.18TICI 06M 0.78

800286-12/pga 48.50800286-8/p1Ce 2440

MCM68A1OP 5.35MM53200N 3.40

06082530-5 132UPD82860 POA ADC84KG-10 12.66

ADC908HP 18.42

L272,4 2.10L29, 3.90L0285A8 2.40LS288B 3.60

REF25Z 1.1202560A POA

TSC76600PA 1.4017109613 4.92

75451 0287545, 0.48

00556A 0.08

000560 0.08

TICP2060 0.61T10'91060 0.24

800858 4.95

800858-2 5 948118-509 7-60

MM58167BN 10 64MM58174AN 14.80MM58274CN 9.18

060874100 12.52UPD8749HC 13.98 ADDA0BON POA

ADG201AKN 4.86ADOPO7GN 2.32

L2974 4.69L4805CV 2.20L487 115

L07210 9.40LT1006CNB 2.72LT1010CT 4.58

7.32

5001027 6.51S0010436 7.9850030496 9.92

U2066B 1641.124000 5.501.1664E1 3.95

75452 128754520 14875453 0.64

00557 0.081305570 0.0800558 0.08

TIP115 0.55716121 0.68T1P145 1.37

93L34DC 7-08AM25LS2558P 268

M0M5832RS 3.39MSM80035RS L90

V20-8MHz 6.95V30-10MHz 12.90 AH0015CD 1720

AY -3-1270 3.60

L4960 3.15L702B 294

LT10280N8LT1032CN 4/0

50050250 7.650AA6002A 10.80

00224060 1.40UA709CP 185

754530 0a475454 0.64

130558A 0.080055813 0.08

TIP2955 0.88TIP30 0.48

AM25LS2569P 268 MSM80039/SMD8.45MSM80C85A 3.95

V30-0MHz 9.20V6103019 250 AY -5-1013 120

LA6250 POAL4635, POA

LT1070CT 9.14LT1083CP 8.82

0AS560S 3.40SED2000FVA 9.60

UA709PC 0.85UA715HC 4.50

754546 0.9875462 0.98

005590 108805590 108

7163055 0.88TIP31A 0.38AM2602PC a30

MSM80085A-2 5.98 VC0106N6 8.60 AY -5-1013A 5.24 LA65, POA LT1086CT /90 SFC2301ADC 618 UA723CP 070 75463 1.10 BC560A 0.08 TIP32A 0.40AM26LS31D0 2.30MSM80086 7.80 Z0800110PSC 16.90 AY -3-1015D 3.60 L465, POA LTCI 052 7.97 SFC274100 0.18 UA733CJ 2.98 75468 3.60 005600 0.08 TIP47 oaoAM261S31PC 1 26

AM275191ADC 10'20AM275281PC 6'25

MSM81055 4.60MSM82051A 3.58

20868112PSC 3.20Z180.MPU 608

AY -5-1250 POA8Y -5 -3600 -PRO 9.96BA6109 1.68

LC7132 POALc7522 POA

LTC4850N8 2.16LTC490 4.40

0035245 4.60517660CJ 1.92

08741 MP 1600074170 028

754, 1.3075470 1508

130184C 0.08BCY71 0.22

V275LA10 0.92VN0104N3 0.92

AM2964BDC 12-36 MSM82053-2 3.98 280018-CPU 11.960A6208 1.40

L,7555 POA M5218AL POA SL1452 6.75 0874806 016 75471 1 68 BD131 0..88 VN66AFD 1.40AM2965DC 6-36

'

MSM82053-5 3.58 28018008VSC 8.25CA3046

0'51LD111ACJ POA M5220 POA SL2364C 3.97 UA748T0 152 75472 1.48 BD135 0.44 VN90AB 2.96

AM2966PC 3 98 MSM82C54-2 4.20 Z80A-CPU 1.25CA3046(SMD) 0°2

LF135080 18.20 M5238L POA SL3117B POA UA7700OUIC POA 75473 1 48 BD24191 098 VP0104-N3 0.92AM298260C 3 34 MSM62059A-2 3.98 ZBOA-CTC 1.98

CA3054 024LF311H 10a0 M5298P POA SL4860P 2.98 UA798TC 180 75474 2.25 BD242C 0.52 VP0104N2 0.98

AM68501 9 82MSM82C84A 3.30 ZEIGADART 3.15

CA3059 120LF347N 2.40 M706B1 1.25 0L490DP 2.80 UCN5800A 240 75477 2.10 8D243 0.50 VP0104N3 192

8M8238PC 5.60 MSM/32084A-2 3.60 ZBOA-DMA 3.95CA3078AT 2A2

LF351N 0.98 MAX12320NG POA SL560CDP 100 UCN5801A 2.60 75491 0, BD516 0.78 ZTX212 118AM90500DC 4.95 MSM82C88 12.60 Z80A-P10 125

°43073 188LF353N 0.86 M821232CPA 3.57 SL62700DP 130 UDN2981A 2.00 75813176 2.88 BD675 0.52 ZTX237 126

AM9050CPC 4.60AM9102CPC 282

N800286 -10/p1 24 501180C2136 -12/p1 29.54

Z80A-S10/0 3.40290B -CPO 1.52 003080E 0.70CA308175ALS193J0.96

LF355N 1.82LF356N 1.82

MAX1259CPE POAMAX162ACNG POA

SL6700CDP a47SN5281CN POA

UDN2982A 200UDN6I 18A 1.65

75ALS192 2.883.22

BD676 0.52130679 0.54

ZTX300 118ZTX3131 0.28

AM9114BOM 9.96 NBOL286-802/9136.20 Z80B-CTC 3.00CA3089E 1.22

LF357BN A98 MAX232ACPE 4.84 SN55451BJG POA UGN3501M POA 75,11542.88 BD680 0.56 ZTX320 0.38

AM9551PC 966 N8235N 3.68 Z80B-DART 5.80CA3094AE 2.16

LF357M/SMD 4.98 MAX232CPE 2.80 SOC12 120 ULN2001AN 0.44 75014, 2.73 807430 1.90 ZTX510 0.18AM96LO2PC 3.35AY -5-8136 6.45AY -5-8138-008 6.45

01164/SMD 4808231A 5900C8253 3.60CA8008513 5 980082085 9.'62CD82086H-5 9.740G80C286-12 4150CGSOC286-16 6a00COM8136 645COM81017 8.15CP82059 6.42CRT -8094-001 9.65058205 8.92D3232 510

N8269N 3.88N82S126AN 3.25N82S181F 10.04NS16450N 4.68NS16550AFN 12.60NSC800N-1 10 80P80328H 4.29P8051AH 11.20P8052AH/BasiC 23 45P80808 3.901380135/02 5.98P8085AH-2 5.98P8088 4 80

-

P80C31BH 4.54P80C8BAL-2 12.60P8155H/2 6'98P8185 18.10

Z80B-DMA POAZ800 -P10 22078013-010 4.50

Z130000A06 298

CA3096AE 3.48CA3096CE 1.82LOWCA3097E 2.60C83120E750189ADPOAC031308T 19.20003130E 1.10CA 0 .314 AE 1 34003140E 0.44003146E 2'22003160E 1.25003240E 2'93CA3240E1 2.1608324E 0-23083260E 1 680832800E 5.94003280E 3'42005550E 0.20

LF357N 1.20LF398N 3.98LF4110N 1.48LF412CN 1.98LF441CN 0.75LF442CN 0.99LF444CN 2.71LH00020N 10.80LH00320G 3160LM101AH S65LM1OCN a24LM111H 6.74

LM13600N 140LM13700N 3.40LMI 391N 3.40LM 1 39J 6.60LM 0a2

MAX232EWE 3.80MAX232N 2.80MAX280CPA 6.94MAX452CPA 5.38MAX627CPA 2.98MAX660CPA 5.72MAX690A0PA 6.58MAX694CPA POAMAX697CPE POAMAX7219CNG 7.15MAX8211CPA 2.28MAX901BCPE POAMCI 377P 4.93MC1413P 0.74MC14411P 11.38MC14416L 17a0MC14495P 4.82

0P1648DG 5S3P4534 POA

SP47400P 4A656862906 144SP8660DP 4.96787215P 7.20TA72566 260TA7368P POA7076586 POATA78005AP POATA8200AH POATA8410K 2.80TA8449P POATA8659AN POAT00861A POATBA1200TBA24013 POA

ULN2002A 0.44ULN2003AN 0.44ULN2004AN 1.40ULN2024A 1.40ULN2032A 1.40ULN2003AN 0.84UM5100 POAUM5101 180XR2211CP POAXTR110KPY1112/11 4.60ZN1445 &08

ZN4142 1.04ZN4I 5E 1.84ZN423 2.20ZN425E-8 5.97ZIX426E-8 168

75,1, 3.98

750188 12075C189A 1.32

1.3275LBC176 2a0

BDT85 1.12130067B 2.78

00790 3.60BF195-C 0.080E199 0.22BF200 0.1613F25613 0.38BF2560 0.380E259 0.408F324 0.28BF421 0.12BF450 0.20BF451 0.22BF494 0.16

0.260F961 0.64

8E981 090

IC SOCKETSPROFILE

No Pin Gold Tin Gold'

01 spacTurn sldr sldrPins -IN Pin Tail Tail

6 0.3 18p 6p 188 0.3 15p 6p14 0.3 31p Op 31p16 0.3 33p 10p 33p113 0.3 39p 11p 39p20 0.3 45p 12p 45p22 0.3 54p 14p24 a3 54p 14p24 16 54p 14p28 16 60p 16p

TELECOM & SPECIAFUNCTION ICs

4

"380820-013 3 70707W02020 S25733W00124 5.25AMA1503GXB AN8001505 1.80CLA25106/PLCC 5 95GA050010DB 3.20KS-49258/PLCO 5.92MJ145408 7.65M651751 3-030C-141-7 2.40

TRANSISTORSTHYRISTORS

& TRIACS

40406 1.6040673 2.40BC107A/13 117BC108A/B/C 0.1700109B/C 118130140-18 0.4800146/01 0.58

D8086 5.48D8086-2 a80

P8205 2.0068212 2.40

600352303 4.3566340108 6.80

08741 CE 0.18CS5503-KD POA

14505LM1496N 2.95LM 801N 7.92

MC45406P 2.10MC1455P 0.40

TBA570 POATBA820MT POA

ZN428E-8 19525429E-8 264

80149 0.40BC157 0.34

BF982 0.88BFG65 1.79

32 0.6 65p 22p40 16 70p 22p

D8202A POA08254-2 6.42D8284A 3a0

P8226 "1382510 3.90P8253 2.80

04704 3000MV168P5 7.98QMV18C 035

007925E1 P08016902 P°8DA00800LCN A10

LM1881N 480LM1889N 7.40LM1894N 4.16

MC1455P1 160MC1458P 132MC1488L 2.40

T0A920 POA700990 POA70910686 POA

ZN449E 476 6°15000-'314400169C

80179 124

BFR53-2G817 0.48BFR91-5GHz 0.900E1391A-60Hz 1.20

48 16 85p64 175 260p64 a 9 260p

D8288 6.480820284-12 960

1382550-5 3.90138259 2.85

QMV180811 7.85OMV18CW1 7.85

DA00832LCN 1167DAC080P 260

LM218H 15.75LM239N 3.90

MC1488P 0.38MC14898 0.80

TCA335A POATCA965 POA PERSONAL COMPUTER - HARDWARE& SOFTWARE

MOTHER BOARDS - VESA LOCAL BUS (W thout CPU & DRAM)Processor Chip BIOS Cache Max Expansion BoardSixe PirceIntel Set RAM Memory Slots In mm 9 p

D820284-8 7.850820288-10 I 0a6D820288-12 11.85

P8259A 3.20P8274 9.98P8279-5 320

QMV25C 8.42QMV62AW1 6.9004534-AMI 4.20

D8008EP 3.64D801008109 10.73DAC122210N 2140

LM290I N 1.25LM2903N 1.25LM2904N 1.25

MC1489AL 2.25MC1489AN 180MC1469L 220

TCM1520AP POATCM1531P POATCM1705AN POA

0820288-8 9.36 P8262SA336931 2.95 DG201ABK 3.83

LM2917N-14 610 MC1489P 038 TCM3105N 9.92087489 9a5DM9601N 2.45

P828632:6640

P82054 4.10P82054-2

SAA5025D 5.40SCM6611 5P 3.40

DG211DG508AGJ 3.98

LM29179-8 5.80LM29400T15 2.95LM2940CT5 250

MC -1496N 2.20MC1558L 3.32MC1648P 12.40

TCM5087N 2.40TCM5089N 1407001083 2.60

80486SX/DX/DX2 SIS AMI 128K 32MB 7,8(AT).2x32(vEsA) 260 x 220 120.008048600/00/002 SIS AMI 2566 32MB 7x16(AT).2.328/ESA) 260 x 220 129.00

0198228N 6.36DP8238N 136 PALI OLBCN 1.90

PAL12H6CN 1.90

SGS7P050 455SP14508 5.76

DG508CJ 3.25DS1488N 2'3°

LM2984CT 7.50LM301AN 0.36

MCI 658P 12.78MC1709CPI 1.20

70010850 296TDA1085C 3.80

MICROPROCESSORS CO -PROCESSORS80286-16MHz INTEL £65.00 80287-8 INTEL £40.00DP8304BN 234

PAL16R4BCN 2.17 ULAIRB029E1 6.80 0S14C88M/SMO 1.65 LM307N 1.39 MC1723CP 1.20 TDA1151 1.1080386DX-40MHz AMD £75.00 80287-10 INTEL £48.00DP8311N 6.54

PAL2OLIOCNS 4.35ULA2ORK008E159.72 D0140889 1.65 LM308N 1.65 MC1741CP 0.45 TDA1170S 2.80

8048600-25MHz INTEL E115.00 80287 -XL INTEL £62.00DSI 221 6.44051 231-20 4.44051232 3.260534885 3 20053487N 3.20

PAL20X80NS 3.32PALC16L203

6.10PALC20L8Z-45000LM312H

XR.T5683 3 60ZNA2L029J-BS 3.80ZNPCM1J-BS 8.95

OPTOELECTRONICS

00140898N 1.65HA12017 1.441-84134213 11.969817723 1.108107518913 POA

LN1310N 2.98164

LM311N-14 2.158.95

MC3242AP 7a4MC3301P 188MC3302P 060MC3340P 1.60

TDA1515A 4.98TDA152IA 4.37TDAI 576 3.9010815786 3.60

8048600-33MHz INTEL £245.00 8038700-33MHz INTEL £62.00804860X-50MHz INTEL £ 56 MEMORIES80486002-66MHz INTEL 00

SIMM 1Mx9x9 CHIP 7Ons P.O.A.SIMM 1Mx9x3 CHIP 7Ons P.O.A.CONNER HARD DISK DRIVES

00340886 9.805.17

HEF4754V 22.20LM317AT 2.60 MC3357P 320 TDA2595 3.32 SIMM 4Mx9x9 CHIP 7Ons P.O.A.CP-30174 170MB 19msec 15' LP £165.013

DS34C87N 4.80 PALC22V10H-35004525 0.60 H11-0201-5 3.60

LM317T 0.52 MC3403P 1.40 TDA3048N 1.85 SIMM 4Mx9x3 CHIP 7Ons P.O.A.CP 30254 2 OMB 15016853 5" LP £212 005DS3631N 3.33

0036325 2.81PCD8584PPCF8566P 8.28

4N26 0 600.404N33LM319NHI1-5088-5 11.21

811-549-5 POA

LM317T-SGS 0.52LM318N 2.98

2.84

MC3446AP 6.75MC3479P 7.92M035230 5.80

TDA3505 P08TDA3810 P08700440 P08

' ' SIMM 256Kx9 CHIP 8Ons P.O.A.CP-30344 340MB 1 3msec 15" LP £290.00

SOFTWARE0036335 133PCF85661 8.28 0.564N36LM32OLZ-12811-574960-5 42.50 014 MC4024P 12.78 TDA4510 138

FLOPPY DISK DRIVES MICROSOFT ORIGINAL0036349 2810036919 4.96DS3862N 7 38055000-32-1 2 47.-50

PCF8570P 7.85PCF8573P 6.72PCF8574P 5.90PCF8574T 5.90

6NI 39 1 6005036 0.38.CNY17-3 0.64CNY2IN POA

H13-0201-5 3101 -R3 -0509A-5 7.15913-201-5 12°HI ILI P°8

LM324AN 3.66LM324J 2.47LM324N 0.64

MCT2 0.84M0761 1.18MFIOCCN 8.95

TDA4563 3.38TDA4660 POATDA7010T POA

ALPS OFR7231,25( .44MB 3.5" 00.111 WINDOWS 3.1TEAC FD -2358F .44MB 3.5' £30.007E80 FD-55GFR .2MB 5.25' £35.00MITSUBISHI MF355C/258MG .44MB 3.5' £2900

£65.00

IMPORTANTAll prices quoted are

008640N 1.2000882074N 295 PCF8591P 9.35

R6502AP 5.70

DF08 140HCPL-2200 a98

H0574 -AK 1820.0L7104-18CPL 26.08

LM325N 9.40LM3301N 2.60

ML924 4.90MM5309N 5.76

7007052 2.527088702 6.22

MITSUBISHI MF504C/318MP .2MB &25" £35.00 Excluding V.A.T.

DS8832N 2.68R6520P HCPL-2231 5.98 L7107C0H/PL00

LM334Z 2.20 MM53I 05N 4.98 TEA1045 POA GRAPHIC CARDS Postage & Packing008836N 294DS8837N 240

4.40R6522 4.40 HCPL-2602 5.68

H0PL-2830 3.685.20

17109CPL 9 85

LM335Z 2.48LM336Z-2.5 1.48

MM80C95N 1.44MP7570JD POA

TEA1060 4.20TEA5620 POA

CIRRUS 1421 6V800 01 -BUS Window Accl. W/I MB 675.08TRIDENT TVGA 8900CL New Trident 1MB SVGAE40.00

Charge of £3.00 isapplicable to all goods

DS8838N 2.40EF6803A-1P 3 80

R6522AP 5.80R65002132 514R65002P3

HCPL-2730 3.45HCPL-2731 3.20

L7116CPL 6.74L7117CPL 6.74

LM336Z-5.0 1.48Lm337,.

1.15MUX24E0 9.60MUX24FP a60

TIPC2801KV 140TL0260P 1.84

TSENG LAB ET -4000 IMB SVGA £60.00

KEYBOARD & MICEunder the heading of'Personal Computer

EF6803P 3.80EF6821P 1130EF68809P 3.18PostageEF68021P 1.44

a90R65002P4 8.95R65C102P2 685R6502162 5.94LM3401-5

HCP1-4200 5.98ILD74 1A4ILO1 1.60ILC174 225

0171260PL 6.74CL7135CPI 8.98CL7136CPL 6.94CL7137CPL

LM339AN 298Lm339N 160LM340AT12

0.48

MV500DP 3.05MV601DP 3.36MV8870DP 5S2NE5020N 10.84

TL.062CN 0.52TL062CP a52TL064CD 098TL0640N 0.88

BTC 7849R 102 UK KeyBoard. Regular Sixe£24.00IMSI SYSTEM MOUSE 3 Button Serial £10.00

Znix 3 BUTTON MOUSE MS COMPATIBLE 10.00

Hardware & Software%

& Packing willbe charged at cost for

EP610PC-35 POA R65C22P2 4 8010074 2.25

6.94CL7606CJN 12.24

LM340T12 0.48 NE527N 3.71 TL0641D/SMD 2.10 I/O CARDSall destinations outside50B80032P 5.95 LM340T15 0.30 NE532N 0.60 TL071ACP 1.84 IDE 2HD/2FD/25/1P/I G with cables 015.00 the United Kingdom.

PLEASE SEE PREVIOUS ISSUES FOR OTHER ITEMS & FEB/MAR 1992 ISSUES FOR LEDs,DISPLAYS & RELAYS.

VIEWCOM ELECTRONICS PLEASE ADD £1.10 P & P and then 17.5% VAT. OFFICIAL ORDERS from Govt. & Educational Establish-ments are accepted. VAT at 17.5% is chrageable to all orders received from EC Member Countries unless77 UPPERTON ROAD WEST VAT Number is quoted. OVERSEAS orders, postage AIR/SURFACE will be charged at cost. VAT is not

PLAISTOW, LONDON E13 9LT applicable for EXPORT orders from Non -EC Member Countries. Stock items by return of post.N.B. All prices are subject to change without notice & stock availability.

PLEASE PHONE/WRITE FOR ITEMS NOT LISTED Retail Shop: 139, New City Road, Plaistow, London E13 9PXELEKTOR ELECTRONICS MAY 1994

10

MAINS SIGNALLING SYSTEMPART 2: TRANSMITTER

Design by W. Hack'ander & S. Furchtbar

Mains signalling is a method by which signals can be superimposed on mains wiring for theremote control of electrical equipment. It was first proposed by two Swiss inventors, Routin and

Brown, who patented the method to control street lighting in 1896. The technique is wellestablished and accepted in the USA, but in this country and Europe interest in it as a mediumfor communication has begun only in the late 1980s. This article deals with a system for use inhome automation. The main advantages of the system are ease of installation, flexibility and

relatively low cost (because it uses existing mains wiring.

Since the transmitter is provided witha microprocessor, the command com-

puter need only send simple instructions.These are translated by the transmitterinto switching codes for specific receivers.At the same time, the transmitter arrangesfor the status of each receiver to be sentback to the computer. Communicationbetween the transmitter and computer isvia a standard RS232 link.

The circuitSeveral sections of the circuit-see Fig. 9-are identical to parts of the receiver cir-cuit. For instance, modulating and de-modulating of the digital signals that aretransferred via the mains wiring are againeffected by an NE5050. Capacitors C15and C16 and transformer Tr2 form partof a 110 kHz transmit oscillator, whosecarrier is switched on and off by the dig-ital signal generated by IC7c. The outputsignal is supplied via R21 and R22 to L1(which provides harmonics suppression),R20 (which provides impedance match-ing), and C12 (which provides d.c. de -coupling). From there, the signal is ap-plied to transformer Tr1 which is linkedto the mains wiring via C14. CapacitorC13 and the transformer form a band-pass filter with a centre frequency of110 kHz.

At the demodulating end, the level ofthe incoming signal (at pin 20) is limitedby D6 and D7, which also suppress anyspurious signals. In the IC, the signal isapplied to an amplifier, to a band-passfilter, Tr3-C6, a low-pass filter, C11, an AMsuppressor, a comparator and a bistable.Finally, it is available at pin 11.

The power supply is conventional: amains transformer, Tr4, bridge rectifier,D8 -D11, buffer capacitor, C18, and tworegulators, IC II and IC12. The first regu-lator, IC 11, provides a direct voltage of12 V, from which IC12 derives a directvoltage of 5 V. Moreover, a direct voltageof 9 V (for the decoder/encoder, IC1) isprovided by R11 -D3.

Circuit IC4 is a miniature control sys-

mainswiring

IIc

recce;er

apparatusLobe

,on,nolled

apparatusrobe

controlled

Setup of a 2 -receiver system. Up to 127 receivers may be accommodated.

tern with a clock frequency of 12 MHz (de-rived from crystal X1).

Circuit IC5 organizes the addresses onthe multiplexed address/data lines P00 -P07.

The control program for the transmit-ter is contained in EPROM IC6.

Optoisolators IC8 and IC9 connectedto pins 10 and 11 of IC4 effect the com-munication between the transmitter andcomputer via the serial interface. Theyare necessary to ensure proper electricalisolation between the transmitter andequipment connected to the RS232 in-terface, since transformer Tr1 does notprovide this. Circuit IC8 passes the datareceived from the computer to IC4, whileIC9 sends data from IC4 to the computer.

Network D1 -R3 at pin 12 of IC4 servesto indicate confirmation of receipt of data.This interrupt input is controlled by T1.

The LED at pin 15 of IC4 lights duringthe transmission of data. Output TOswitches NAND gata IC7d viaT2.

The data for the receivers are sent overlines Pl. 0-Pl. 7.

Coding and decoding of the receiveraddresses are carried out by IC1. Net-work R1 -C1 sets the internal clock of thisIC to 45 kHz. When the address of a givenreceiver is sent, the relevant data are avail-able at the P... gates of IC4, from wherethey are applied to IC1 via buffer IC3 andlevel compensator/inverter IC2.

Circuit IC7 and transistors T1 -T3 en-sure the correct switching sequence dur-ing transmitting and receiving. If, for in-stance, a receiver needs to be switchedover, the processor provides the correctaddress at P1 and, via pin 14, gives theinstruction for this address to be sent.Transistor T2 raises the level from 5 V to9 V and inverts the signal. The output ofIC7d then goes high, whereupon T3 con-ducts, so that the output signal of themodem IC is suppressed to prevent IC1receiving back its own data during trans-mission.

NAND gate IC7d sets IC1 to the trans-mit mode via its mode input and enablesIC7b. The serial data then becoming avail-able at pin 17 of IC1 are passed via IC7band IC7c to IC10, where they are modu-lated and applied to the mains wiring. Thecode is transmitted several times in suc-cession, which is indicated by the flick-ering of D2, while D1 lights permanently.

After about 15 seconds, output TO ofthe processor goes low, which causes IC1to switch from transmit to receive (modeinput goes low, IC7b is disabled, and T3switches off, so that the signals receivedby IC10 are applied to pin 16 of IC1). Twoaddresses monitor whether the slave re-acts: that just transmitted and this ad-dress plus a '1' in the tenth position, fromwhich the switching status of the receiver


MAINS SIGNALLING SYSTEM - PART 2 mbecomes clear.

When, within a given period, a validaddress is received four times, pin 17 ofICI goes low. This signal is passed topin 12 of IC4 via inverter IC7a and levelcompensator/inverter T1. This is indi-cated by DI going out. Confirmation ofreceipt of the data is then given to thecomputer by IC4.

IC7 = 4093

9V

IC1 18

12V

13

120p

17

OSC

REC/TR

MODE

REC IN

DS1

DS2

DS3

DS4

DS5

DS6

DS7

DS8

DS9

DS10

DS11

DS12

JEz02

,Sz05

ULNL122 2803

8 1z

9

10

12

14 MM53200

+vs

<1

IC2

VEE

15

1617

18

ConstructionBuilding the transmitter is simpler thanthe receiver. All components are housedon a genereously sized printed -circuitboard, which, for safety's sake, is intendedfor installation in a man-made fibre en-closure. The use of sockets for the ICs isrecommended: this is not only convenientfor the construction but also for the cal-

IC374HCT541

EN

r1 18 V

2 17

5V

9

40

RESET

419 16 WR

,417

2 1

3 16

3 2

4 15

4 3

14

5 4

6 13

6 5

7 12

7 6

8 ,

7

9

5V

IC7a

2 ffs,

6 5

IC7b

4 IC7c8

if&

Tr3

BS170

R5

R40

19

R18

C62n2

8

44 R3

D1

5V 0-44 R2

9V

R10

02

R9

BC547

12V

0

T3

.L7

:100n

R19

42015k6

C11

TXIN RXOUT

OUT1 RXIN

Idl 0POP161

FB

NPNOUT2

NE5050CFO

CDET1

LC

IA12

4n7 8 CDET2

CHPF VC2

CAM y CIMP

20

TO

INTO

12V

O

17

6

R21

105-2

D7

15R22

2x

12

BZT03/C15

C12

470n a

Ll

390µH

C15 Tr2

1312p

14

C16 ow2n2

1 4

9

18

W

7n TOOn

C1010

4201

C17

1100n

RD

P1.0

P1.1

P1.2

P1.3

P1.4

P1.5

P1.6

P1.7

INTO

13 INT1

14 TO

1C4

P0.0

P0.1

P0.2

P0.3

P0.4

P0.5

P0.6

P0.7

P2.0

P2.1

P2.2

P2.3

P2.3

P2.5

P2.6

P2.7

80C31 ALE/PPSEN

RXD

TXD

15 TI EAP.T,

1 X1 X2

120 J19 X 1

C3

123

:100n

ibration.Screw the backs of regulators IC11 and

IC12 together with in between a U-shapedheat sink. They need not be isolated.

Provide holes in the top of the enclos-ure for K2 and the three 5 -mm LEDs (forsafety's sake, do not use 3 -mm types be-cause these may protrude from the en-closure). Provide a hole in one of the shorter

IC5

10 r> V

5Ve

1 28 27

19 10

38

37 AD2 /.**, AD2 4

36 AD3,/ ' AD3 5

35 A04AD4 6

33 16 8

32 9

21 A8

22 A9

23 A10

24 All25 Al2

26

27

28

30

18 9

8

16 7

15 6

14 5

11

12 3

Cl

EN

74HCT573

29

A8 25

A:240 21A

All 23Al2 2

VPP 0 PGMAO

A2

A3

A4

A5

A6

AlA8

A9

A10

All

DO

IC6 0/

EPROMD4

D5

D6

D7

27C64

D2

2 NC

OE ... CS

C24

100n

1 ADO/12

AD2

15 AD3

16 4E1/4

17 ADS/16A3619 AD7

33p 73pX1=12MHz

10

1

31

5V

14 IC9

R17

22

141k

135

1N4148

26

K2

GND 5

RxD 3

TxD 2

R15

5V

CNY65

12V

7

916

5V

940021 - II - 11

6

O

OOO

O0


Fig. 9. Circuit diagram of the mains signalling transmitter.

m GENERAL INTEREST

side for mains cable (use a strain relief)entry.

Do not yet place the ICs into their sock-ets; this should be done during or aftercalibration.

CalibrationThe transmitter and one receiver are re-quired for calibration. Make sure that theground of the units is connected to themains earth. Stick insulating tape overall PCB tracks that carry mains voltageto prevent them being touched by acci-

940021-2

dent. It is better to screw the transmitterboard to the bottom inside of the enclos-ure, whicn effectively prevents any of themains -carrying tracks to be touched.

Begin by checking that all supply volt-ages at the IC sockets are as specified (donot insert the test prods into the socketterminals to prevent these losing theirelasticity).

When the voltages are correct, switchoff the mains and insert IC 10 into its socketTemporarily interlink pin 19 and pin 1,whereupon a sine wave at an amplitudeof about 9 VPP should appear on an os-

C21 T3

°I1" CIO1

1 1

6

01.00C24 e

C20

V6IC5

cilloscope connected to pin 16. Measurethe frequency of this signal with a fre-quency meter and adjust to 110 kHz byturning the core of Tr2 with a plastic screw-driver. If a frequency meter is not avail-able, use a long -wave radio receiver (pre-ferably with digital dial). Tune the radioto 330 kHz (3rd harmonic of 110 kHz),place it close to the transmitter (in a po-sition where the 50 Hz mains hum is notor least noticeable) and turn the core ofTr2 for minimum noise output of theradio. Next, connect the oscilloscope acrossTr1 (at the side with the centre tap) with

12

R7

1 v -0 R6.^^0 R5

f;')31 T1

a a

as

so+C19

10.12

C7 01 1

R81R18 10

CI

ITR3

C9

C40

K1

TR4

TR1

940021-2

Fig. 10. Printed circuit board of the mains signalling transmitter.


MAINS SIGNALLING SYSTEM - PART 2

Fig. 11. Completed transmitter before enclosure is closed.

the oscilloscope ground to the +12 V ter-minal: disconnect the mains earth fromthe unit earth, since the ground of theoscilloscope is normally also connectedto the mains earth. Adjust the core of Tr'for maximum signal level on the oscillo-scope.

Then, connect the oscilloscope to pin 3or pin 6 of IC 0, where a square wave atan amplitude of about 0.5 V and a d.c. off-set of around 4.5 V should be available.

Next, connect the oscilloscope topin 4 or pin 5, where a sine -wave -like sig-nal with a sort of cross -over distortionshould be present. Adjust the core of Tr3so that the the distortion peaks are sym-metrical around the cross -over points. It

r

will probably not be possible to obtain thesame picture at pin 4 as at pin 5, but tryto make them as identical as feasible.

Disconnect the link between pin 1 andpin 19 and insert the remaining ICs intotheir sockets and close the case.

In the receiver, take all ICs from theirsockets and check the supply voltages.When these are all correct, insert IC2 intoits socket and carry out exactly the sameprocedure as just described for IC io inthe transmitter.

Insert the other ICs into their sockets.With the use of jump leads, set the de-

sired address on K1: the numbering is bi-nary - no jumper at K1 gives address 0and seven jump leads give address 127.

Fig. 12. Take care during the calibration: there is always the risk that open mainsvoltage is present somewhere on the board.

For instance, address 1 (decimal) requiresa jump lead on K1 at the side of pin 1 ofIC5 (call this connection 1); address 100(decimal), i.e., binary 1100100, needsjumpers on connections 3, 6 and 7. Markthe address on the outside of the case forfuture reference. Close the case.

Taking into useInsert the receiver into a mains outlet andconnect a mains -operated apparatus toit. At this stage, it is advisable to keep thereceiver in sight.

Insert the transmitter into a differentmains outlet and connect it to the com-puter via a serial cable of which all wiresare linked 1:1, that is, not with the sendand receive lines crossed as in a standardserial cable.

Start the program on the computerwith the aid of diskette Ref. 1913 (seeParts List). The computer monitor showsan operating panel on which with themouse or the keyboard (Alt plus under-lined character) a COM port may be se-lected. It is also possible for a relay num-ber to be keyed in, whereupon the soft-ware can switch over the relay. The re-mainder of the procedure is shown on themonitor.

It is also possible to send instructionsmanually to the transmitter with the aidof a communication program such asTelemate, Unicorn or Procomm. The trans-mitter recognizes the following:

R (52hex)-reset transmitter (the programin the transmitter starts from the be-ginning).

C (43hex)-clear status transmitter (onlystatus bits are reset).

T (54nex)-switch over the receiver: afterthe T, the address (0-127) of the rele-vant receiver must be sent as a byte.

S (53hex)-demand status transmitter: inthis case, the transmitter sends backa byte containing the following data:

bit 0 - receiver status (0 = relay notactuated; 1 = relay energized). Thisis valid only if reception was cor-rect.bits 1-3-not used.bit 4 - syntax error: the commandsent by the computer is not recog-nized.bit 5 - time out of 20 s: the bit be-comes '1' if during this time no an-swer from the receiver has come in.bit 6 - busy write: this is high dur-ing the period when the transmit-ter is waiting for an answer from thereceiver.bit 7 - busy read: this high duringthe period when the transmitter oswaiting for an answer from the re-ceiver.

It is, of course, possible for an indi-vidual program that uses these commandsto be written in, say, Pascal or BASIC.


14 GENERAL INTEREST

Parts list

Resistors:Ri = 180 ki2R2, R3, R6, R12,R4 = 3.91{QR5, R7, R8, R10,

R9, R18, R19 = 5Rii = 180 QR13 = 4.7 IcQR15 = 390 QR17 = 1 IcQ

R20 = 47 QR21, R22 = 10 SI

-

k Mittorfstresse 17 0-40735 Knelt)

Slocitable Contomicat ion -Ports:

COW iit O3/!h

FurchtbarMa2/7402252

Rollo r 10..1271

Modem Status Text

R16 = 2.2

R14= 10 ki2.6 kQ

Fig. 13. Control program as seen on the computer monitor.

Capacitors:C1 = 220 pF, polystyreneC2, C5, C19, C20 = 10 pF, 16 V, radialC3, C4 = 33 pFC6, C16 = 2.2 nF*, pitch 5 mmC7, C9, C17, C21 -C24 = 100 nF*C8 = 10 nFC10, Cu = 4.7 nFC12 = 470 nFC13 = 6.8 nF*C14 = 470 nF, 630 VC15 = 12 pFC18 = 220 pF, 35 V, radial* = polypropylene (MKT)

Inductors:L1 = 390 pI-1

Semiconductors:D1 = LED, 5 mm, yellowD2 = LED, 5 mm, greenD3 = zener, 9.1 V, 1 WD4 = LED, 5 mm, redD5 = 1N4148

D6, D7 = BZT03/C15D8 -D11 = 1N4001T1, T3 = BC547T2 = BS170T4 = BC557

Integrated circuits:ICI= MM53200N (National Semiconductor)IC2 = ULN2803IC3 = 74HCT541IC4 = 80C31IC5 = 74HCT573IC6 = EPROM Ref. 6371 (see p.70)IC7 = 4093IC8, IC9 = CNY65IC10 = NE5050N (Philips/Signetics)ICii = 7812IC12 = 7805

Miscellaneous:K1 = 2 -way terminal block. pitch 7.5 mm

K2 = 9 -pole male D connector,right-angled for PCB mounting

X1 = crystal, 12 MHzTr1 = transformer T1001

(Toko No. 707VXT1002N)Tr2, Tr3 = transformer 4201

(Toko No. LPCS4201 or LMCS4201) or4100, 4101, 4102, 4200 or 4202 (alsoToko)

Tr4 = mains transformer, 15 V, 3 VAe.g., Velleman 1150038M (Maplin)

1 off heatsink 27 K W-1 (Fisher TypeFK228/SA from Dau, telephone(0243) 553 031

1 off enclossure 200x112x51 mm(77/8x47/16x2 in), e.g., Bopla TypeEG2050L - in UK represented byPhoenix Mecano Ltd, telephone(0296) 398 853

1 off PCB Ref. 940021-2 (see page 70)1 off diskette Ref. 1913 (see page 70)

*Further information on the general as-pects of mains signalling may be ob-tained from the BEAMA Interactive andMains Systems Association, LeicesterHouse. 8 Leicester Street, LondonWC2H 7BN. Telephone 071 437 0678.Fax 071 437 4901.

In general, for domestic applications,the level of the signal signal appliedacross the mains wiring must not ex-ceed 116 dB pV (631 mV). Measuredacross the line or neutral terminal andground, the level must not exceed 316 mV(110 dB pV). The specified impedancemust be 50 SI

Third harmonic spurious radiationsmust not exceed 57 dB pV (0 7 mV).

EN 50 065-1 specifies a frequencyrange of 95-125 kHz.

In practice, these requirements meanthat only small energy levels may be ap-plied across the mains wiring. This inturn means that the receiver must befairly sensitive and that spurious sig-nals and the 50 Hz mains hum mustbe suppressed adequately. Moreover,as extra precautions, switching in-structions must be sent several times,while at the receiver, received codes arecompared several times


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16

MORSE DECODER

Some of you may call them hopelessly old-fashioned, but theycan still be heard at many frequencies when tuning across theshort-wave bands, those unsurpassed long and short tonesused to convey messages by radio. Telegraphy, or morse, stillexists in the face of the tremendous strides that have beenmade in modern communication technology. The morsedecoder described in this article is available as a kit fromVelleman distributors, and enables those cryptic tones fromyour communication receiver to be deciphered, and turnedinto text on a liquid crystal display.

At.

ek

Design: © '94 Velleman N.V., Belgium.

MORSE or telegraphy code is acommunication method developed

at a time when it was impossible toconvey speech reliably over large dis-tances using radio links. The morsetransmitter is the simplest type oftransmitter in existence because basi-cally it is switched on and off by amorse key. Using a relatively simpleprotocol, the 26 letters in the alphabet,numbers 0 through 9, and a number ofpunctuation signs, are encoded into aseries of short and long tones, whichare often called 'dots' (short tones) and`dashes' (long tones).

Morse transmissions can be re-

ceived in the short-wave and long -wavebands using a communication receiverfitted with a narrow IF (intermediatefrequency) filter and a beat frequencyoscillator (BFO). To the uninitiated,morse code is just a series of meaning-less tones. Experienced morse opera-tors (or `telegraphists'), however, arecapable of copying messages from veryweak signals buried under a lot of in-terference. Meanwhile, they will chatwith you, write down the message andsmoke a cigarette. This proficiencylevel and skill is impossible to achievewithout training and years of experi-ence. Not surprisingly, many amateurs

prefer the automated solution, forwhich the present morse decoder is theperfect companion.

The circuitThe circuit diagram of the morse de-coder is given in Fig. 1. Broadly speak-ing, the schematic may be divided intothree parts. The circuit around IC2turns the morse signal into a digitalpulse train. The digital circuit aroundmicrocontroller IC1 turns the digitalpulses into text which can be read on aliquid crystal display (LCD). The dis-play used is capable of showing up to16 characters on one line.

The third section of the circuit is thepower supply, which consists of amains transformer (2x8 V at 150 mA),a double -phase rectifier, and an inte-grated 5-V regulator. Obviously, thetransformer may be replaced by a suit-able mains adaptor with an outputvoltage of between 9 and 12 V.

The input stage of the morse de-coder is simple, but effective. The ana-logue signal picked up by the electretmicrophone is applied to the input ofIC2 via a coupling capacitor. TheXR2211 in position IC2 is an integratedFSK (frequency -shift keying) demodu-lator/tone decoder from Exar. Asshown by the internal block diagram inFig. 2, this IC contains all componentsneeded to use it as a tone decoder.

The design of a tone decoder shouldtake into account the wide frequencyspread of the morse tones. The actualfrequency of the morse tones producedby the communication receiver is neverfixed because it depends on the exacttuning and, in some cases, the BFO(beat frequency oscillator) setting.Hence, the frequency to which the tonedecoder responds is made adjustable.This adjustment is carried out with po-tentiometers RV3 (frequency) and RV4(lock range). Components C4, R11 andRV3 turn the VCO (voltage controlledoscillator) contained in the XR2211into a variable frequency oscillator.The detector, another sub -circuit of theXR2211, compares the frequency of theoscillator output signal with that of themorse tones picked up by the micro-phone. Since the frequency of themorse tones can vary considerably, acertain capture range is provided, thespan of which is determined by R8 andRV4. With the component valuesshown, the decoder is capable of lock-ing on to frequencies between 77 Hzand 240 Hz with RV3 set to minimum.This capture range is changed to550 Hz to 1720 Hz with RV3 set to


MORSE DECODER

R3

R2100k 1

NCC3 010 -

J.LV

LD

470k

+VCC +VCC

TR

R8

RV4100kLOCKRANGE

R11

RV3FREQUENCY25k

CT

C4I33n

9

10

11

12

13

14

+ VCC

7

6

IC2 5

XR2211

4

2

DO

R R6

- R910k

+VCC

T1+VCC

BC557

c0

'4 R12

LD1

410Iiip/16V

T11

R10 D1

11N4148+ VCC

LDF

I 47n

R4T6

I

..L

IN

100n

+VCC

C7

MIC

SENSITIVITY

RV2soon

R1

CM -105-8

X1

-1[1 I6MHz

15p 15pMINIM

T1 1.2

1N4001

26 40 P2.7

P2.6

P2.5

27

101 2829

8748 3031

3233

7 20 34

+VCC

R7

RV15k

CONTRAST

+VCC

7RS

R/WE

DOD1

D2D3D4D5D6D7

3 2

56 LCD7 MODULE9 LMO2OL10It (Hitachi)121314

7805 + VCC

949501 - 12

Fig. 1. Circuit diagram of the morse decoder, which is available as a kit through Velleman distributors.

maximum. In both cases, the lockrange pot, RV4, is set to maximum. Theadjustment of the two potentiometerscan be optimized as soon as a morsetransmission is picked up, and the firstcharacters start to appear on the LCD.The two adjustments serve to minimizethe decoder's susceptibility to noise,which is unfortunately inherent toradio signals.

The sensitivity of the decoder is ad-justed with RV2. It is recommended touse the lowest possible sensitivitywhich allows a good degree of acousticcoupling to be achieved. As with thepreviously mentioned frequency andlock range adjustments, this helps tokeep the distorting effect of noisesources beleaguering the morse signalsto a minimum. If desired, R1, RV2 andthe microphone may be omitted, andreplaced by a simple input stage with aresistor of 47 ki2 to ground. This allowsthe decoder to be connected directly tothe receiver's line output.

The correct operation of the tone de-coder may be verified by looking at LEDLID'. If the LED lights in the rhythm ofthe morse tones, you may safely as-sume that the tuning and other adjust-ments are correct or about correct.

Apart from to the LED driver, T1, the

morse signals are also applied to theinput of microcontroller IC1. The con-troller runs at a clock of 6 MHz, andturns the serial datastream at its inputinto corresponding parallel codeswhich can be recognized by the LCD.Preset RV' serves to set the LCD con-trast for the best legibility/brightnesstrade-off, which will take you only halfa minute or so to find.

The microcontroller used here is aType 8748 from Intel's MCS48 family.The 8748 has on -board RAM and ROM.The decoder software is located inROM, and has been developed byVelleman N.V.

Components R10 and C11 supply themicrocontroller with a reset signal atpower -on. Diode DI ensures that ca-pacitor C11 is discharged rapidly whenthe circuit is switched off. CapacitorC11 has a value of 10 I.tF in the kit sup-plied by Velleman. Based on practicalexperience, we recommend changingthis into 100 pF to ensure a more reli-able reset.

ConstructionAssembling the decoder is easy

using the components and the printedcircuit board contained in the kit. The

track layout and component mountingplan of the printed circuit board de-signed for the morse decoder areshown in Fig. 3. Construction isstraightforward, and no problems areexpected to arise if you work carefully.The LC display module is fitted on to

+VCC 1

INPUT 2

LOCKDETECT E

FILTER

GROUND E

LOCKSDETECT

OUTPUI TS

DATAU

OUTPUT

XR-221I

14

SIGNAL

PRE AMP

WAD0-DET

LOCKDETECTCOMP

41-

VCO

LOOP0-DET

-E14

TIMING

CAPACITOR

ETIMINGRESISTOR

11

INTERNAL I_10

REFERENCE

F,SK _11.1P

LOOP

DETOUT

REF

VOLTAGEOUT

NC

FSK

COMP INPUT

949501-11

Fig. 2. Internal organization of the XR2211FSK demodulator/tone decoder (courtesyExar).


18 RADIO AND TELEVISION

' P. 111111111111,11

3J WAM3JJ3V

11111 I11

1).471)

10 VELLE AN

000

ICI

a*********0

RV17-7 1 TO LCD -MODULE 14 p00000000000000 ts) -E

0IR? i0 0 ' i ci 2-,--` C9 2 T

VRI T R2 05C8

C12 + -0n_ 1I.

oi D2 1[0 roo0 0 0 -6-VR 1 VB

sr

IC2t46,00.000.01

007 000{ RI 10

_0 0+MI C

4909us co

CCm

LD1

T1

0O

RV4

RV3

81211

CC

0

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4-1

1-4

U)

Fig. 3. Track layout (reflected) and component mounting plan of the single -sided PCB in-cluded in the kit.

Fig. 4. Completed morse decoder. If desired, the unit may be built into a suitable case.

Resistors:R1 =1505]R2 = 100k0R3,R4 = 4701QR5,R6,R71= 41(07R8 = 47kQR9 . 10k0R10 = 1kQR11. 15kQR12 . 3300RV1 = 51d1 presetRV2 = 500Q presetRV3 = 25kQ presetRV4 = 100k0 preset

Capacitors:C1,C2 = 15pFC3 .10nFC4 = 33nFC5,C6 = 47nFC7,C8,C9,C10 .100nFC11 . 100pF 16VC12 . 470pF 16V

Semiconductors:IC1 = programmed 8748 (supplied by

Velleman: order no. VK2659)IC2 = XR2211VR1 . 7805T1 = BC557D1 = 1N4148D2,D3 = 1N4001LD1 = LED red

Miscellaneous:Mic = M300 or CM -105-8.X1 = quartz crystal 6MHzTr1 = 2x9V/4.2VA (e.g. Velleman

2090050M).One 1 -line, 16 -character LCD module,HLM1615 or Hitachi LM020L.

Kits for the morse decoder are avail-able from

Maplin Electronics, P.O. Box 3,Rayleigh, Essex SS6 2BR. Tel. (0702)554161, fax (0702) 553935.

Cirkit Distribution Ltd., Park Lane,Broxbourne, Herts EN10 7NQ. Tel.:(0992) 444111, fax (0992) 464457.

the board with the aid of four PCB pil-lars. This is done after all other partshave been mounted on the board. Thedisplay is connected to the board viashort lengths of flexible wire. Insert thespindles into the three presets on theboard, and connect the microphone viaa short length of screened wire, so thatit can be mounted close to the re-ceiver's loudspeaker.

Apply power, and check that the dis-


MORSE DECODER 19

Morse, a simple codeThe morse or telegraphy code was developed to convey messages over radioand telegraph wire links with a very limited bandwidth. Apart from the completealphabet, the code set also includes numbers and a couple of punctuation signs.The complete morse alphabet was developed by Samuel Morse, who lived from1791 to 1872. This American is also the inventor of the writing telegraph (1837).All morse codes are a combination of two elementary characters: a dot (.) and adash (-). The dot has a length of one time unit, the dash, a length of three units.The length of the pause between a dot and a dash, but also between a dot and adot, and a dash and a dash, is fixed at one unit. The length of the pause betweenletters, numbers or signs equals three units. Similarly, the pause between wordsor number groups equals six (or seven) time units. The actual length (say, in ms)of the time unit is not defined, and is merely a relative indicator of thetransmission speed. In most cases, however, a time unit is simply equal to a dot.

LettersA

CDEF

G

J

K

L

MN

P

B

R

TU

V

XYz

Numbers1

2

34567890

- - - -- -

*

...... ...... - *

- - --

Punctuation signs * -..

...... rm.. a.m.

Special codesWarningErrorRepeatWait (AS)Break (BK)Copied (VE)Transmissionreceived (R)Start ofmessage (KA)End ofmessage (AR)End oftransmission (K)End oftransmission (KN)Closing sign (SK)Transmitterclosedown (CL)

mow*

****** --.6

* ......

- -

play reads 'Velleman kit'. This indi-cates that the hardware is operational.Switch off again.

AdjustmentBefore you can start adjusting the var-ious controls on the morse decoder, itis necessary to tune to a strong, clear,morse transmission. In many cases,these can be picked up from CoastGuard and similar utility stationstransmitting at countless frequencies

across the short-wave bands. The pro-totype of the kit assembled in our de-sign laboratory was tested with themorse signals received fromScheveningen Radio (PCH2O) coastguard on 4,250 kHz. Set the receiver toCW mode, or SSB using the BFO, andadjust the tuning until the morse tonessound as clear as possible. Some back-ground noise is normal and no causefor alarm. In any case, make sure youuse a good antenna, and select a sta-tion which remains on the air for some

, ,

Fig. 5. The morse decoder in action. Anymorse signal can be picked from the `aether',decoded into text, and thrown on to a

scrolling LC display for you to read.

time (in most cases, that will be a util-ity station, not a radio amateur).

Next, switch on the morse decoder.After the test message 'Velleman kit',the decoded text should scroll alonghorizontally across the display. Usingthe LED as an indicator, the best pos-sible adjustment of the tone frequencyand the lock range will soon be found.Reduce the receiver volume, or the de-coder sensitivity, if the LED appears tolight continuously, since that indicatesthat the circuit is being overdriven. Ifthe LED is nearly always out, the mi-crophone does not pick up enough sig-nal, and the acoustic coupling shouldbe examined.



SURVEILLANCEpRoFESSNEVAL Malin KITS

No. I for KitsWhether your requirement for surveillance equipment is amateur, professional or you are just fascinated by this unique area ofelectronics SUMA DESIGNS has a kit to fit the bill. We have been designing electronic surveillance equipment for over 12 yearsand you can be sure that all our kits are very well tried, tested and proven and come complete with full instructions, circuitdiagrams, assembly details and all high quality components including fibreglass PCB. Unless otherwise stated all transmittersare tuneable and can be received on an ordinary VHF FM radio.

Genuine SUMA kits available only direct from Suma Designs. Beware inferior imitations!UTX Ultra -miniature Room TransmitterSmallest room transmitter kit in the word! Incredible 10mm x 20mm including mic.3-12v operation. 500m range £16.45

MTX Micro -miniature Room TransmitterBest-selling micro -miniature Room TransmitterJust 17mm x 17mm including mic. 3-12V operation. 1000m range £13.45

STX High-performance Room TransmitterHi performance transmitter with a buffered output stage for greater stability and range.Measures 22mm x 22mm including mic. 6-12V operation, 1500m range £15.45

VT500 High -power Room TransmitterPowerful 250mW output providing excellent range and performance. Size 20mm x40mm. 9-12V operation. 3000m range £16.45

VXT Voice Activated TransmitterTriggers only when sounds are detected. Very low standby current. Variable sensitivityand delay with LED indicator. Size 20mm x 67mm. 9V operation. 1000m range £19.45

IIVX400 Mains Powered Room TransmitterConnects directly to 240V AC supply for long-term monitoring. Size 30mm x 35mm.500m range £19.45

SCRX Subcarrier Scrambled Room Transmitter

Scrambled output from this transmitter cannot be monitored without the SCDM decoderconnected to the receiver. Size 20mm x 67mm. 9V operation. 1000m range £22.95SCLX Subcarrier Telephone TransmitterConnects to telephone line anywhere, requires no batteries. Output scrambled sorequires SCDM connected to receiver. Size 32mm x 37mm. 1000m range £23.95

SCDM Subcarrier Decoder Unit for SCRXConnects to receiver earphone socket and provides decoded audio output toheadphones. Size 32mm x 70mm. 9-12V operation £22.95

ATR2 Micro Size Telephone Recording InterfaceConnects between telephone line (anywhere) and cassette recorder. Switches tapeautomatically as phone is used. All conversations recorded. Size 16mm x 32mm.Powered from line £13.45

*** Specials ***DLTXIBLRX ladle Cenlrot SwitchRemote control anything around your home or garden, outside lights, alarms, pagingsystem etc. System consists of a small VHF transmitter with digital encoder and receiverunit with decoder and relay output, momentary or alternate, 8 -way dil switches on bothboards set your own unique security code. TX size 45mm x 45mm. RX size 35mm x90mm. Both 9V operation. Range up to 200m.Complete System (2 kits) £50.95Individual Transmitter DLTX £19.95Individual Receiver DLRX £37.95

IMX-1 11141 Micro BreadcastsaNot technically a surveillance device but a great idea! Connects to the headphone outputof your Hi-Fi, tape or CD and transmits Hi-Fi quality to a nearby radio. Listen to yourfavourite music anywhere around the house, garden, in the bath or in the garage andyou don't have to put up with the DJ's choice and boring waffle. Size 27mm x 60mm.9V operation. 250m range £20.95

9

UTLX Ultra -miniature Telephone TransmitterSmallest telephone transmitter kit available. Incredible size of 10mm x 20mm!Connects to line (anywhere) and switches on and off with phone use.All conversation transmitted. Powered from line. 500m range £15.95

TLX700 Micro -miniature Telephone TransmitterBest-selling telephone transmitter. Being 20mm x 20mm it is easier to assemble thanUTLX. Connects to line (anywhere) and switches on and off with phone use. Allconversations transmitted. Powered from line. 1000m range £13.45

STLX High-performance Telephone TransmitterHigh performance transmitter with buffered output stage providing excellent stabilityand performance. Connects to line (anywhere) and switches on and off with phone use.All conversations transmitted. Powered from line. Size 22mm x 22mm.1500m range £16.45

TKX900 Signalling/Tracking TransmitterTransmits a continous stream of audio pulses with variable tone and rate. Ideal forsignalling or tracking purposes. High power output giving range up to 3000m. Size25mm x 63mm. 9V operation £22.95

CD400 Pocket Bug Detector/LocatorLED and piezo bleeper pulse slowly, rate of pulse and pitch of tome increase as youapproach signal. Gain control allows pinpointing of source. Size 45mm x 54mm. 9Voperation £30.95

CD600 Professional Bug Detector/LocatorMulticolour readout of signal strength with variable rate bleeper and variable sensitivityused to detect and locate hidden transmitters. Switch to AUDIO CONFORM mode todistinguish between localised bug transmission and normal legitimate signals such aspagers, cellular, taxis etc. Size 70mm x 100mm. 9V operation £50.95

QTX180 Crystal Controlled Room TransmitterNarrow band FM transmitter for the ultimate in privacy. Operates on 180 MHz andrequires the use of a scanner receiver or our ORX180 kit (see catlogue). Size 20mm x67mm. 9V operation. 1000m range £40.95

QLX180 Crystal Cointrolled Telephone TransmitterAs per QTX180 but connects to telephone line to monitor both sides of conversations.20mm x 67mm. 9V operation. 1000m range £40.95

QSX180 Line Powered Crystal Controlled Phone TransmitterAs per QLX180 but draws power requirements from line. No batteries required. Size32mm x 37mm. Range 500m £35.95

QRX180 Crystal Controlled FM ReceiverFor monitoring any of the '0' range transmitters. High sensitivity unit. All RF sectionsupplied as a pre -built and aligned module ready to connect on board so no difficultysetting up. Outpt to headphones. 60mm x 75mm. 9V operation £60.95

A build-up service is available on all our kits if required.UK customers please send cheques, POs or registered cash. Please add£1.50 per order for P&P. Goods despatched ASAP allowing for chequeclearance. Overseas customers send sterling bank draft and add £5.00 perorder for shipment. Credit card orders welcomed on 0827 714476.

OUR LATEST CATALOGUE CONTAINING MANY MORE NEWSURVEILLANCE KITS NOW AVAILABLE. SEND TWO FIRSTCLASS STAMPS OR OVERSEAS SEND TWO IRCS.

9

- I:

. I:



Ivirmr=minniummguawanskiratirmswaimais TEST and MEASURE

with yourCOMPUTER.

Oscilloscopes30.0 niJ

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HandyscopePRINTER PORT

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MULTI INSTRUMENTS

COLOUR SOFTWARE

MultimeterDigital Voltmeter

Spectrumvolt RC SPECTIIUI fKiLYSER

400

200 volt 15000 Its Rectangle

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12Th24 Hz

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120 Hz

240 Hz

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1200 Ks

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FREQUENCY tam I EINEAIR I AIRNIGE I DISIORTICII

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mAplettme: 0.100 scale: 1.000 offset: 0.000 file: DAL TNAM.DAT

For more information on the HANDYSCOPE and other data acquisitioninstruments please contact...

INSTRUTEK (UK)TEL: (0480) 460028 FAX: (0480) 460340.


DIFFERENTIAL PROBEFOR OSCILLOSCOPES

Design by H. Bonekamp

The probe described overcomes several of the shortcomingsof the probe supplied with many oscilloscopes. It is a

10:1/100:1 design that enables floating measurements to becarried out. Its presettable attenuation to 10 V or 100 V and itsfacility for floating measurements makes it also suitable for

measuring high voltages.

en the resistive or capacitive loadconnected to many oscilloscopes is

too large, serious measurement errorsmay occur. Moreover, the voltage rangeon many oscilloscopes is limited to 5 Vgraticules, so that the maximum voltagethat can be measured is 40 V. This is, ofcourse, improved by the supplied 10:1probe to 400 V, but even this is inade-quate for many applications. Anotherproblem with a number of oscilloscopesis created by the external (mains) earthbeing permanently connected to the groundof the instrument. Since, moreover, theequipment on which measurements arecarried out is often also connected to themains earth, a potentially dangerous sit-uation may arise when very high voltagesare measured. This also means that mea-surements are always referred to earth:in mains -operated apparatus it is virtu-ally impossible to measure the potentialbetween two random points.

Differential measurementsMeasurements not referred to earth canbe made only by using a differential probe.Such a probe has two prods, each of which`floats' with respect to earth. An accuratedifferential amplifier/buffer ensures that

the probe is provided with the true po-tential difference between the prods.Differential probes with presettable at-tenuator are commercially available, buttend to be fairly expensive. The presentprobe is considerably less so.

Since the probe must not noticeablyload the equipment on test, its input re-sistance is high and its input capacitancelow. Moreover, the input is frequency com-pensated to ensure that linear perfor-mance is obtained over a wide frequencyrange. The attenuator networks for eachprod are as nearly equal as possible.Moreover, the common -mode suppres-sion is high.

The circuitThe circuit-see Fig. 1-is based on spe-cial dual differential amplifier ICI. This isa wide -band device that provides accu-rate processing of a differential input sig-nal. Moreover, it attenuates common -mode signals up to very high frequencies.Basically, it consists of two separate dif-ferential amplifiers followed by a commonbuffer. Pins 1 and 2 respectively form the+ve and -ve inputs of one and pins 3 and4 those of the other. The common outputis available at pin 7. Feedback networkR10 -R11 fixes the amplification at x2. Thepotential divider at pin 4 ensures accu-rate compensation of the d.c. offset (owingto the offset current, the value of R9 isequal to that of R10 and R11 in parallel).

The attenuator networks are situatedbetween ICI and connector K1 (to whichthe test prods are connected). They con-sist of precision resistors R1 -R7. Frequencycompensation is provided by capacitorsC1 -C8. With values as specified, the inputresistance is about 2 MQ and the inputcapacitance around 2.5 pF. Moreover, thespecified values ensure that the time con-stants in the probe are determined by theactual components rather than by para-sitic effects.

Since for good common -mode sup-pression equality of the networks is im-perative, one has a fixed 10-Q resistor(R4), whereas the corresponding (20-Q)resistance in the other is variable (P1).This arrangement makes it possible forany measurement error to be nullified.

Attenuation

CinUhl, (differential)Uin (common mode)Bandwidth

CMRR

Accuracy (see text)

PARAMETERS

100:1 or 10:12 MC (approx)<2.5 pF (without test leads)450 V peak; 450 V r.m.s.700 V peak; 500 V r.m.s.20 MHz (100.1)15 MHz (10:1)80 dB (up to 100 kHz)60 dB (up to 1 MHz)40 dB (up to 10 MHz)0.6% max (100:1)


DIFFERENTIAL PROBE FOR OSCILLOSCOPES

Moreover, variable capacitors C4 and C8enable equality of the networks to beachieved at high frequencies.

Although the wanted maximum at-tenuation factor is 100:1, the input at-tenuator is set to 200:1. This is to keepthe differential input voltage of ICI withinlimits: the AD830 has internal limitingthat comes into operation when the levelof the differential signal reaches 2.3 V.As the amplification of the device is x2,the final attenuation is 100:1.

Because of the internal limiting in IC1,it is not possible to switch the input at-tenuator to 10:1 without degradation ofthe common -mode suppression. This isresolved by adding amplifier IC2. The am-plification of this stage can be switchedbetween 1 and 10, so that the attenua-tion can be switched between 10:1 and100:1. So as to affect the bandwidth ofIC2 as little as possible, the input resis-tance, rather than the feedback resis-tance, is switched (by Si) between 1 ki2(R12) and 100 Q (R12 in parallel with R13).

The output impedance of the probe is

C1 C24p7 4p7

400V 400VR1 R2

C5 C64p7 4p7

400V 400VR5 R6

P1

205-2

MT

R1...R3, R5...R7 = 0.1%

R9...R15 = 1%

R8, R16 = 5%

R3

R4

R7

C3

C7NEN

390p

50 Q (R15) to ensure good matching toRG58 coaxial cable.

The operating voltage for the probe isprovided by a standard supply. The twopower lines are stabilized by regulatorsIC3 and IC4. Each rectifier diode is shuntedby a capacitor to eliminate any spurioussignals. Diode D1 functions as an on/offindicator.

Note that each of the ICs is individu-ally decoupled for r.f. by C17 -C18 andC19 -C20 respectively: this measure is nec-essary with fast devices.

As already stated, attenuator resistorsR1 -R7 are close -tolerance (0.1%) types,whereas R9 -R14 are precision (1%) types.This gives an overall measurement ac-curacy of 4.2%, which is an acceptablepractical value. If maximum accuracy(0.6% in the 100:1 position and 1.6% inthe 10:1 position) is required, R9 -R14 mustalso be 0.1% types. If 0.1% resistors cannot be obtained, R1 -R7 may be 1% types,but the value of R4 and P1 must then beincreased to 100 Q and 200 Q respect-ively. This not only degrades the mea-

120p

AD830AN

0

TOOn

15V

C9...C12 = 4x 47n

S1

surement accuracy, but may also affectthe equality of the networks adversely andreduce the common -mode attanuation.

ConstructionThe probe, including its power supply, isbest built on the printed -circuit boardshown in Fig. 2. Because of the high sig-nal frequencies likely to be encountered,mount the ICs directly on to the board:do not use sockets. A number of compo-nents must be soldered at both sides ofthe board. Since, for safety's sake, con-ductors carrying high voltages must beseparated by 6 mm, remove the centreterminal of terminal block K1. Mount S1directly on to the board and solder itsmetal case to earth.

When all components have been fit-ted, three tin plate screens have to be in-stalled: one around each of the attenua-tor networks and one around the activecircuits. These screens are shown in Fig. 2and Fig. 3. They must be about 15 mmhigh and be provided with holes for ad -

15V

0L19

:100n

TOOn

O15V

IC3

R15

15V

15V

940018 - 11

Fig. 1. Circuit diagram of the differential probe for oscilloscopes.


24 TEST & MEASUREMENT

justing C4, C8, P1 and P2, aswell as for accepting the spin-dle of Si. Solder them to pinsplaced in suitable positionson the board. Make sure thatthe distance between com-ponents and screens is notless than 6 mm. Cover thecompartments so formed witha tin plate lid soldered in place.

Fit a tin plate screen (ofwhich the edges have beenbent at right angles) over thetrack side of the board. Coverthe inside of this lid with asheet of thin polythene to en-sure that the screen does notshort circuit any of the tracksor solder pads.

The board is intended tobe fitted in an man-made fibreenclosure of 150x80x55 mm(6x31/8x23/16 in). The en-closure may be finished atthe front and side as shownin Fig. 4.

Connect the prods to ter-minal block K1 via 30 cmlengths of flexible multi -strandcable. Connect the probe tothe oscilloscope via a 60 cmlength of RG58 coaxial cable.Terminate this cable at oneend into a BNC connector andsolder the other end to pinsPC I and PC2 on the PCB.

CalibrationCalibration must be carriedout with S1 in position 10:1.It is advisable to let the probewarm up for about 15 min-utes before starting the cal-ibration.

Short-circuit both inputterminals to earth. Connectthe probe output to an oscil-loscope or millivoltmeter setto its most sensitive d.c. range.Adjust P2 until the d.c. (off-set) measured is zero.

Interlink the input termi-nals and apply a direct volt-age or low -frequency voltagebetween this link and earth.Connect the probe output toan oscilloscope or millivolt -meter set to its most sensi-tive d.c. range. Adjust P1 forzero reading. This sets thecommon -mode rejectionratio (CMRR) at low fre-quencies.

Connect a 1 kHz squarewave signal between input1 and earth. Connect the output of theprobe to an oscilloscope. Adjust C4 untilthe oscilloscope shows a neat square wave.Then do the same at input 2. This setsthe frequency compensation.

Interlink the input terminals and con -

L 0940018

9- -

0

0K2

Fig. 2. Printed -circuit board for the differential probe for oscilloscopes.

nect the probe output to an oscilloscope.Inject a 1 MHz sine wave signal betweenthe linked inputs and earth. Carefully ad-just C4 and C8 in turn until the ampli-tude of the signal on the oscilloscope isas small as feasible. This sets the com-

JJ

1

0

mon -mode rejection ratio at high fre-quencies. Check the setting of the fre-quency compensation.


DIFFERENTIAL PROBE FOR OSCILLOSCOPES

Parts listResistors:R1, R2, R5, R6 = 4991(Q, 0.1%R3, R7 = 4.99 k52, 0.1%R4 = 10 Q, 1%R8 = 330 kf2, 5%R9 = 249 Q, 1%

Rii= 499 c2, 1%R12, R14 = 1.00 k52, 1%R13 = 110 Q, 1%R15 = 49.9 Q, 1%R16 = 1.2 kit, 5%P1 = 20 C2 multiturn presetP2 = 20 IcS2 multiturn preset

Capacitors:C1, C2, C5, C6 = 4.7 pF, 400 V,ceramicC3, C7 = 390 pF, ceramicC4, C8 = 120 pF trimmerC9 -C12 = 47 nFC13, C14 = 100 pF, 40 V, radialC15, C16 = 10 pF, 16 V, radialC17 -C20 = 100 nF

Semiconductors:B1 = B80C1500D1 = LED, 5 mm, red

Integrated circuits:ICI = AD830ANIC2 = AD844ANIC3 = 7815IC4 = 7915

Miscellaneous:K1 = 3 -way terminal block, pitch 5 mm

(remove centre terminal)K2 = 2 -way terminal block, pitch 7.5 mmS1 = single -pole slide switchPC1, PC2 = solder pinTr1 = mains transformer, 2x15 V, 3 VAEnclosure 150x80x55 mm

(6x31/8x23/16 in)(for instance Bopla Type E440BB-inUK available from Phoenix Mecano,telephone 0296 398 853)

PCB Ref.940018

Fig. 3. Completed prototype with lid removed; note the three screened boxes.

MAINS

DIFFERENTIALOSCILLOSCOPE PROBE

PEAK 700VRMS 500V


Fig. 4. Suggested side and front panel marking (not available ready made).


41.

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PicoScope'Virtual instrument' softwarepackage. Storage oscilloscope

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ADC -10 single channel 8 bitUp to 24kHz sampling rate froma 386/33MHz machine0-5V Input rangeBNC input connector allowsuse of standard scope probes30V overload protectionParallel port connection

ADC -12 single channel 12 bitUp to 18kHz sampling rate0-5V Input rangeBNC input connector allowsuse of standard scope probes30V overload protectionParallel port connection

Typical application ADC

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ADC -11 eleven channel 10 bitTL'- Up to 18kHz sampling rate

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PricesADC -10 with PicoScope

ADC -10 with PicoScope and PicoLog

ADC -11 with PicoScope

ADC -11 with PicoScope and PicoLog

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ADC -12 with PicoScopeand PicoLog

ADC -16 with PicoLog

PicoLog (for ADC -10/11/12)

Oscilloscope probes (x1 x10)

£49

£59

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8051 BOOK £49.95A very good text on the 8051 architecture, programming and

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.. . . 1100AGO Valve Tester 00160 . L75

PHILLIPS PM5193 Programmable synthesizer/Function Generator 0.1MHZ - 50MHZ IEEE -488.As new £1500

MARCONI 2018 Sotheozol run/FM Skg OCT BOKHz 52019, . 1900

ACAL 9081 Synthesvea Sig Gen 1.5 520MHz £600

IP/DANA 3410 Mcrowme Frequency Cooler 20H1 18GHz MO. .RACAL/DANA 199111an05ec0rA Un sorsa! Goumer L800

RACAL '2 RE M003Itractor Toe RMS 10KHz 1.56Hz r'4.ACAL ' . 4 RE Molivoltrreter True RMS 10KHz 1 591az L300

RACAL nuun AutomaUc Mon. Meter 10MHt1.56Hz Ode Connor L250

LYONS PG73N Pulse Gen. PRF 1He - 20MHz . . . L150

EITHLEY 224 Programmable Current Source .. 1000

FARNELL PSG520 Syn. AM/FM sig. Gen 1001400 -52000, . L800HILLIPS PM6300 DISTORTION Meter eon, E300

H.P. 5341A Frequency Comte- SO 5Hr

RACAL 1998 Frel Canter 1.36Hz"Gallo NO St., .. 15°°-

AY MILANO Line Voltage AnaSser .. - .00H.P. 747004,0tter 2 pen HOB

- 1200

FARNELL ISOLATING TRANSFORMERS0U500 240V 500A Un-Used £50

ISOLATING TRANSFORMERS 500A Un-Cased £30

NEW EQUIPMENTNAMED OSCILLOSCOPE OA 1005 Tr.ple Trace 100MHZ.

elay TImebase . .. . . .. . . L847AMEG OSCILLOSCOPE Ring ZOO Dual Trace 60MHZ.

elay Sweep . £653AMEG OSCILLOSCOPE MA 3 7 Dual Trace 20MHZomponest Tester L362AMEG OSCILLOSCOPE ....I., ' r Dual Trace 20MHZ

g1al Storage L653All otner m, : .. . i h e all scilloscopes Supplied with 2 probes

BRUEL a KJOER Vibration Exciter SystemConsisting of Exciter Control 1047: Power Amp

2708 & Exciter Body 4802 (up to 1780M - 4001W)

OTHER B&K EQUIPMENT AVAILABLE

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METEOR 600 FREQUENT'', roUNTER 60OMHZ . L145METEOR 10008669010. 0006E7 1GHZ . L1891UPITOR 500 FUNCTION GENERATOR 0.1 NO5OCKHZ. Slne/Sp/Tri L.11.9

ORION COLOUR BAR GENERATOR Pal/TV/Video .. L229Al. stnex Black Star Equipment evadable.

H.P. 141T with 85555& IF Plug -In 10MHz 1881-1z £1800

H.P. 1411 with 85548 0 8552B. 9006/1 1250MHZ £1300

H.P. 1401 wlth 8554E & 85520 500KHz 1250MHz £1000

H.P.141T with 8556A& 8552B 20117 - 3001<lif 61000

H.P. 1401 with 85536 & 8552A 160Hf 110MHs .. 1800

H.P. 182C with 85588 10011, - 1500MHz £1500OSCILLOSCOPE PROBES Swrchable xl x10 (PUP 53) . .. . .. .. £12

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28

GENERAL PURPOSE SENSORMONITOR

Sensors and transducers are interesting electronic devices towork with, but the snag is that their output signal invariablyrequires a made -to -measure amplifier that enables an indicatorcircuit to be driven. LDRs, temperature sensors, strain gauges,they all need an amplifier with very specific characteristics.The amplifier described here is designed to handle almost anysensor signal, has adjustable switching thresholds, and will beinvaluable for quick experiments with a wide variety ofsensors, both polarized and unpolarized.

Design by M. Haas

THE heart of the circuit shown inFig. 1 is formed by the trusty 741

opamp, IC4. Here, the 741 is wired as acomparator with hysteresis. The sen-sor voltage arrives at the non -invertinginput, pin 3, via a low-pass filter, R4 -C3, which serves to suppress fast sig-nal variations. The inverting input ofthe opamp, pin 2, is held at a referencelevel which is adjustable with presetP1. As long as the voltage on pin 3 islower than that on pin 2, the output of

the 741, pin 6, will remain low (approx.0 V). The output swings high (to about10 V) if the voltage on pin 3 is higherthan that on pin 2.

Hysteresis is introduced by R7 andP2 which feed a small portion of theoutput voltage back to the input. Theopamp output voltage is fed to twoNAND Schmitt trigger gates, IC 1c andIC id, via low-pass filter R8-05. The twogates are inverters, and allow a singlejumper to select between a relay which

is normally energized or normally off.The choice between jumper A or B de-pends on the comparator's output levelunder normal conditions, and, thus,on the type of sensor used.

The relay is driven by transistor T1via resistor R9. LED D2 gives an extraindication of the current relay state (onor off). Since the relay coil current isgreater than the maximum permissiblecurrent through the LED, the two de-vices can not be connected in seriesjust like that. Shunt resistor R10 pre-vents a too high voltage across the LED(i.e., too much current through the de-vice).

The relay contacts are brought outto pins on connector K2. The pinmarked 'P' is the pole, while 'NO' and`NC' mark the normally open and nor-mally closed contact respectively.

Although the contacts of the relaymentioned in the parts list are, in prin-ciple, capable of switching the mainsvoltage, that should not be attemptedfor the sake of safety. If you still wishto switch mains operated loads, mountthe relay off the board, in a separate,ABS, enclosure. For the sake of safety,use grommets and strain reliefs for themains wiring, and isolate the relay pinswith heat -shrink sleeving.

BistableThe output signal of the comparator isalso used to clock a D -type bistable,IC2b. Because the D (data) input of thebistable (pin 9) is tied permanently tothe +10-V supply rail, the Q output willgo high on the first positive -going edgeof the clock signal. The high level of Qis used to drive T2 into saturation,whereupon LED D3 lights. That condi-tion is maintained until the circuit isreset manually by pressing switch Si.The LED so indicates that the circuitwas actuated at least once, which isvery useful if it is used as a sensormonitor which operates unattended forlong periods. Note that such a memoryfunction can not be obtained from therelay, because that is simply a 'slave' tothe comparator output.

InputsThe input of the sensor monitor con-sists of four electronic switches, IC3a-IC3d, and an oscillator built aroundIC la and IC lb. The oscillator supplies asquare wave signal with a frequency of


GENERAL PURPOSE SENSOR MONITOR 29

K1

0

IC3a

IC3b

1 OV

0(3 C10 (ID

IC3 IC2 IC4

(;)TOOn

14C4

T4216V

14

IC1

cr)

01ov

27k

C2MEI

100n

RS

C3

IC1 = 4093IC2 = 4013IC3 = 4066

11...26V

P2

L4810CV

7

1 0 V

04

4

BC550C , BC557

S1

1N4148

nn110

R11

10V

Re

D2

-a- .

T1

K2

BC557

10V

R13

D3

T2

12 BC550C

916107% - 11

Fig. 1. The circuit consists of a comparator, a relay, and four electronic switches driven by an oscillator.

about 1 Hz. This signal is fed tobistable IC2a, which divides it by two,and provides two complementary out-put signals with a frequency of 0.5 Hz,and a duty factor of 0.5. These signalsare available on outputs Q (pin 1) andQ (pin 2), and control the four elec-tronic switches contained in IC3.

Assuming that output Q is high, andQ low, switches IC3b and IC3d areclosed, and the other two, open. Inother words, the 'left-hand' side of thesensor (which is wired to K1), is con-nected to the +10 V line via IC3b andresistor R3, while the 'right-hand' sideis taken to ground via IC3d.

One second later, this situation isreversed: the Q output of IC2a is logichigh, switches IC3a and IC3c. are closed,and the other two, opened. The right-hand side of the sensor is then con-nected to the +10-V rail via IC3, andR3, while the other side is connected toground via IC3a. In other words, thesensor connections are 'reversed' at arate of 0.5 Hz. The purpose of thisarrangement will be discussed furtheron.

Low-pass filter R4 -C3 prevents thecomparator from noticing the openingand closing of the electronic switches

(unless the sensor is a polarized type,which will also be reverted to below).

Power supplyThe circuit is powered by a ready-mademains adaptor, which is safer and (inmany cases) less expensive than a sep-arate transformer. The type of adaptorrequired is one with a direct outputvoltage between 11 V and 26 V. Theadaptor output is stepped down to10 V by a three -pin fixed voltage regu-lator Type L4810. The more common7810 is not used here because it wouldrequire an input voltage of at least13 V, which means that at least 3 V is'wasted'. By contrast, the L4810 intro-duces a voltage drop of only 1 V, whichmeans that less supply power isneeded.

ApplicationsTo start with, it is, of course, possibleto use two electrodes to form a sensor.This could be used to monitor the con-ductivity or concentration of a certainsolution. Alternatively, you may wantto use an LDR (light -dependent resis-tor), which has a high resistance in the

dark, and a low resistance in the light.Consequently, the sensor voltage at thecomparator input will be high in thedark, and low in the light.

A potentiometer may also be used asa positioning sensor to check the oper-ation of a mechanical device. For tem-perature measurements, an NTC(negative temperature coefficient) or aPTC (positive temperature coefficient)resistor may be connected up.

The above sensors are all non -polar-ized. Consequently, they pass currentin both directions, and may be con-nected both ways around. Polarizedsensors may also be used. The sim-plest of these is created by connectinga diode in series with the previouslymentioned LDR. Consequently, currentcan flow in one direction only. That hasthe following effect: as it grows dark,the sensor voltage rises to a level wherethe comparator toggles, and the relayis energized (or de -energized, depend-ing on which jumper is fitted).However, as soon as the polarity of thesensor is reversed (by the oscillatorand the electronic switches), the com-parator will toggle again. This on/offchange is repeated over and over again,so that the relay is switched on and off


30 TEST AND MEASUREMENT

K2(1.0NC

p

0 0Ref

Di02

C2 o-o

D3

op0-0P2

OIR14 p I

aSi° 00

ti

T20P1

0o0+

Fig. 2. Track layout (direct reading) and component mounting plan of the PCB designed forthe sensor monitor (PCB not available ready-made).

at a rate of 0.5 Hz. In certain cases,this may boost the attention drawingeffect of, for instance, an alarm sirenconnected to the relay contacts. The`trick' may also be applied to the previ-ously mentioned 'positioning' poten-tiometer.

A photodiode forms a polarized sen-sor without the help of an extra diode.Photodiodes may be connected eitherway around, taking into account thatthe operation of the relay changes 180degrees. The same may, of course, beachieved by moving the jumper to theother position, or by swapping the NOand NC relay contacts.

Construction

The artwork of the printed circuitboard designed for the sensor monitoris shown in Fig. 2. Unfortunately, thisboard is not available ready-madethrough the Readers Services, so thatyou have to produce it yourself fromthe drawings given, or build the circuiton prototyping board.

The board is populated in the usualway, that is, starting with the wirelinks and the low -profile parts, fol-lowed by the taller parts. The ICs arefitted last.

After a careful check on the solderwork and the orientation of the polar -

Resistors:R1,R2 = 3M09R3 =R4 = 27kilR5,R9,R14 = 11d2R6 = 2kfl7R7 = 82k0R8 = IMQR10 = 1500R11 = 10k0R12 = 221d2R13 = 390aP1 = preset 10162P2 = preset IMLI

Capacitors:C1,C2,C9,C10 = 100nFC3,C5 = 22nFC4 = 2p2 16V radialC6 = 10pF 16V radialC7 = 100pF 63V radialC8 = 1pF 16V radial

Semiconductors:D1 = 1N4148D2,D4 = LED red 3mmD3 = LED green 3mmT1 = BC557T2 = BC550CICI = 4093IC2 4013IC3 = 4066IC4 = 741IC5 = L4810

Miscellaneous:K1 = 2 -way PCB terminal block, raster

7.5mm.K2 = 3 -way PCB terminal block, raster

7.5mm.S1 = SPST push-button.Re1 = PCB mount relay, 12V, e.g.

Siemens V23127 -80002-A101.Mains adaptor socket.Case: e.g., 0KW A9030087(150x80x5Omm).

ized components, the board may be fit-ted into suitable enclosure. The photo-graph in Fig. 3 shows our prototype,which may give you further ideas as re-gards construction. The circuit is thenalmost ready for use.

AdjustmentThe reference voltage at the invertinginput of the comparator may be variedbetween about 2 V and 7.3 V with pre-set P1. To enable the comparator totoggle, the sensor output voltage mustlie in this range. Remember, the sensorforms a voltage divider together with R3(100 kil). Consequently, to enable a



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74LS-Series74LS0074LSO174LSO274LS0374[SO474LS0574LSO874LSO974LS1074LS10774LS10974LS11741_511274LS11374LS11474LS1274LS12274LS12374LS12574LS12674LS1374LS13274LS13374LS13674LSI 3874LS13974[51474L514574LS14774LS14874LS1574LS15174LS15374LS15474LS15574LS15674LS15774[515874[616074LS161741_416274LS16374LS16474LS16574LS17074LS17374LS17474LS17574LS19074LS19174LS19274LS19374LS195741_519674LS19774LS2074[S2174LS2274LS22174LS240741_024174LS24274[S24374L524474LS24574LS24774LS25174LS25774LS25874LS2674LS26674[S2774LS27374LS27974LS3074[53274LS36574LS36774LS36874LS3774LS373741_537474L037574LS37774[537874LS38741_539074L539374LS39574LS39974LS4074LS4274LS4774LS5174LS670741_57374[S7474LS7574[57674LS8374LS8574LS8674LS9074LS9274LS93

£0.22£0.14£0.14£0.14£0.14£0.14£0.14£0.14£0.14£0.23£0.21£0.17E0.21£0.21£0.21£0.14£0.31£0.31£0.21£0.21£0.14£0.21£0.18£0.16£0.24£0.25£0.18£0.56£1 .26£0.70£0.14£0.25£0.25£0.70£0.25(0.36£0.25£0.25£0.32£0.32£0.32£0.32£0.26£0.48£0.30£0.24£0.24£0.24£0.25£0.2400.42£0.24£0.24£0.24£0.24£0.16£0.14£0.14£0.36£0.32£0.32£0.32£0.32£0.32£0.36£0.32£0.24£0.24£0.24£0.14£0.14£0.14£0.32£0.25£0.14£0.14£0.21£0.21£0.21£0.14£0.32£0.32£0.34£0.32£0.62£0.14£0.25£0.24£0.26£0.62£13.14£0.25

02£0.14£0.69£0.17C2

£0.19£0.25£0.31£0.35£0.20£0.23£0.35£0.25

ENAMELLEDCOPPER

WIRE

All 2oz Reels14 SWG £0.6316 SWG £0.6718SWG £0.67205WG £0.7222 SWG £0.7624 SWG £0.8026 SWG £0.8928 SWG £0.9130 SWG 0.9332 SWG £0.9334 SWG £0.9936 SWG £1.0438 SWG £1.1040 SWG £1.22

4000 Series40004001400240064007400840094010401140124013401440154016401740184019402040214022402340244025402640274028402940304031403340344035404040414042404340444046404740484049405040514052405340544055456740634066406740684069407040714072407340754076407740814082408540864089409340944095409740984099450245034508451045114512451445154516451845204521452645274528452945324534453645384541454345554556456045664572458445854724401064010940163401744017540193

£0.17[0.21£0.17£0.400.28£0.31£0.19£0.23£0.26£0.16£0.21£0.30£0.31£0.18£0.27£0.27£0 19£0.31£0.31£0.32£0.16£0.21£0.15£0.59£0.18£0.22C0.36£0.17£0.70£0.56E1 .24£0.31£0.29£0.31£0.22£0.28£0.35£0.31£0.25£0.31£0.20£0.20(0.36£0.25£0.25£0.56L0.34

8.13.53

£0.29£0.18£1.91£0.16£0.20£0.17£0.20£0.17£0.17£0.17£0.30£0.17£0.14£0.21£0.280.26£0.55£0.18£0.31£0.56£1.20

£0.38£0.38£0.31£0.90£0.26£0.32£0.32£0.77£0.98£0.31£0.27£0.26£0.62£0.40£0.40£0.40£0.44£0.32£2.48£1.00£0.37£0.33£0.46£0.34£0.34£1.18£1 .96£0.25£0.24£0.32£0.70£0.31£0.50£0.46£0.34£0.36£0.60

TRANSISTORS2N16132N17112N18932N221 BA2N2219A2N2222A2N26462N2904A2N2905A2N29072N29262N30532N30542N30552N34402N37022437032437042N37052N37062N377124377225137732N38192N38202N39042N39052N39062440362452962453212N6107AC126AC127AC128AC187AC188ACY17AD149AD161AD162BC107BC1076BC108BC108ABC108CBC109BC109CBC1I 4BC115BC116BC118BC132BC134BC135BC140BC141BC142BC143BC149BC154BC157BC159BC160BC170BC1706BC171BC1716RC172BC172BBC177BC178BC179BC182BC182LBC182LBBC183BC183LBC183LBBC184BC184L

£0.31£0.26£0.29£0.28£0.25£0.16£0.80£0.25£0.23£0.20£0.16£0.27£0.90£0.62£0.50£0.090.10£0.10£0.10£0.10£1.44£1.51£1.79£0.40£0.58£0.10£0.10£0.10£0.31£0.57£0.57£0.60£0.30£0.30£0.28£0.45£0.37£3.84£1 67£0.92£0.92£0.14£0.15£0.13£0.14£0 16£0.14£0 1--£0.41£0.41£13.41£0.41£0.36£0.36£0.36£0.25£0.27£0.31£0.340.21£0.36£0.12£0.12£0.28£0.16£0.16£0.11£0.16£0.13£0.13£0.18L0.18£0.17£0.08£0.08£0.08£0.08£0.08£0.08£0.08£0.08

TRIACSZ01050A £0.42TIC206D £0.65T1C226D £0.73BTA08-60013 £0.84TIC2360 £0.96DIAC £0.20

VOLTAGEREGULATORS

78L0578L1278L1579L0579L1279L15780578127815790579127915LM317TLM723L200CVLM323KLM338K

£0.24£0.24£0.24£0.28£0.28£0.28£0.28E0.28£0.28£0.38£0.38£0.38(0,56£0.29£1.16£2.70£5.52

OPTO DEVICES5mm Red LED5mm Green LED5mm Yellow LED5mm Orange LED3mm Red LED3rnin Green LED3mm Yellow LED3mm Orange LED5mm Flashing Red5mm Flashing Green5mm Bi Colour5mm Tri Colour5mm Plastic Bezel3mm Plastic Bezel03" 7 Segment Display Redcommon anodecommon cathode

£0.09£0.10£0.10£0.10£0.08£0.12£0.13£0.13£0.50£0.54£0.36£0.48£0.04£0.05

£1.14£1 14

BC186BC204CBC206BBC207CBC208BC209ABC212BC212LBC212LBBC213BC213LCBC214BC214LBC2376BC238CBC239CBC251BC252BC261BBC262BEl C2671380307BC308BC327BC328BC337BC338BC414C40441BC461BC463BC478BC479BC490BC516BC517BC527BC528BC537BC546CBC547CBC548CBC549CBC550CBC556ABC557CBC558CBC559CBC56013BC637BC638BC639BC640BCY70BCY71BCY72

D135BD136BD137BD1388013980140BD150CB0165130166BD187

0201B020280203B D204B D222El 0225BD232Et 0237BD238802408BD243BBD244ABD246BD441130442

£0.33£0.72£0.72£0.72£0.72£0.72£0.08£0.08£0.08£0.08£008£0.08£0.08£0.09£0.09£0.10£0.13£0.13£0.24£0.24£0.300.10£0.10£0.10£0.10£0.10£0.10£0.13£0.40£0.40£0.29£0.32£0.32£0.24£0.22£0.20£0.20£0.20£0.20£008£009£0.080.10£0.08£0.08£0.08£0.08£0.08£0.09£0.21£0.21£0.21£0.210.21£0.20£0.20£0.20L0.21£0.22£0.22£0.23£0.24£0.82£0.42£0.35£0.39£0.40£0.40£0.40£0.40£0.40£0.42£0.38£0.32£0.32£0.37£0.50£0.53£1.06£0.41£0.41

8D534BD535BD536BD646BD648BD650BD707130807B0X32BDX33CBDX34CBEIX53C130)(54CBF180BF182BF1856E194130195B F2445E257BF2598E3378E355BF423BF451BF459B F469BFX29BFX84BFX85B FY50B FY51B FY52B 5107BS170BSW66BUl 26BU205BU208ABU326ABU500BU508ABU52613l1806BUX84IR F540190740MJ11015MJ11016MJ2501MJ3001MJE340MJE350M PSAI 3M PSA42MRF475TIP121TIP122TIP125TIP127TIP132TI P137TIP142TI P147T102955TIP29CTIP3055TIP30CTIP31CTIP32CTIP33CTIP41ATI P42CTI P47TI P48TIP50VN1OKMVN66AFZTX300ZTX500

THYRISTORS180102AATICI 06DTIC11 6DTIC126D

£0.30£0.40£0.66£0.77

£0.47£0.48£0.65£0.52£0.52£0.53£0.42£0.80£1.78£0.46£0.50£0.47£0.50£0.31£0.31£0.31£0.19£0.19£0.35£0.33£0.33£0.36£0.38£0.13£0.19£0.29CO 36£0.29£0.31£0.31£0.29£0.26£0.28£0.21£0.21£1.35£1.70£1.82£1.73£1.80£2.32£1.76£2.24£1.36£0.78LI .60£1.63£2.11£2.11£1.60£1.52£0.40£0.42£0.12£0.17£6.21£0.35£0.37£0.37£0.37£0 46£0.46(1.08£1.12£0.63£0.31£0.63£0.31£0.34£0.32£0.72£0.36£0.38£0.48£0.62£0.53£0.44£1 .50£0.16£0.16

HARDWARET2 Box 75x 56 x 25mm £0.82T3 Box 75 x 51 x 25mm £0.82T4 Box 111 x 57 x 22min £0.98MB1 Box 79 x 61 x 40mm £1 44MB2 Box 100 x 76 x 41mm £1.56MB3 Box 118 x 98 x 45mm £1.82MB5 Box 150 x 100 x 60mm £2.50

LINEAR ICsCA311ECA324CA555CA741 CECA747CECA3046CA3080CA3130003130ECA3140CA3240ICL7621ICM7555ICM7556LM301ALM348NLF351NL F353LM358NLM377LM380NLM381LM386LM387LM392NLM393NLM748CNLM1458LM3900LM3914LM3915MC3340MC4558NE531N E556NNE567NN E5532N E5534TBA120STBA810STBA820MTDA2030TL061TL052TL064TL071 CPTL072CPTL074CNTL081T L082CPTL084CNUA733ULN 2003ULN2004ZN414ZZN425EZN426EZN427EZN428EZN435EZN448E

£0.2803 35£0.22FO 28£0.39£0.37£0.72£0.98£0.98£0.56£1.22£1.70£043£0.96£0.25£0.31£0.36£0.41£0.27£2.57£1.12£2.70£0.48£1.60£0.79£0.280.31£0.26£0.72£2.70£2.70£1.60£0.36£1.56£0.36£0.36£0.80£0.66£0.77£0.68£0.39£1.35£0.35£0.42£0.46£0.32£0.34£0.48£0.33£0.34£0.46£0.64

£0.52£0.48

.04£4.68£2.61£8.82£6.12£5.31£7.92

EPROMS &RAMS

271627322764-2527C64.2521728-2027C128-2027256-2027C256 - 20

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MI I II I II II


ElGENERAL PURPOSE SENSOR MONITOR

GENERAL PURPOSE SENSOR MONITOR

0POWER

0ACTIVE

RESET

0RELAY

911117X -f

Fig. 3. Suggested front panel layout.

suitable switching threshold to be set,the sensor must have an impedancebetween about 32 1d2 and 270 kO. Asensor having an impedance of be-tween 10 kS2 and 20 kg2 is, therefore,not suitable straight away, becausethen the voltage at the non -invertinginput of the comparator can never be-come high enough for the comparatorto toggle. If you still want to use such asensor, you have to change the value ofR3 to satisfy the following two equa-tions:

Rsens(min)/(Rsens(min)+R3) X 10 V -2 V;

and

Rsens(max)/(Rsens(max)+R3) X 10 V -- 7.3 V.

Briefly, this means that the voltage di-vider formed by R3 and the sensor hasto be calculated again, whereupon theswitching threshold and the amount ofhysteresis can be adjusted with P1 andP2 respectively.

Correct adjustments of these twopresets is awarded with good sensitiveand an accurate switching point with-out relay 'chatter'

ElectrodesMeasuring the concentration of asaline solution is possible by measur-

Fig. 4. Completed prototype.

ing its conductivity. Two electrodes (forinstance, copper ones) are immersed inthe solution, a current is sent throughthem, and the voltage drop is mea-sured. Since pure water does not con-duct, the resistance formed by thesolution, and therefore the voltageacross the electrodes, is a measure ofthe concentration of 'salt' ions in thesolution. Ordinary tap water conductsonly because it contains a fair concen-tration of dissolved salts, and, there-fore, many (positive or negative) ions.

The sensor monitor could be used tokeep a continuous check on a certainconcentration level. Unfortunately,electrolysis occurs readily if a directcurrent is sent through the electrodes.Electrolysis causes a number of chemi-cal reactions to occur at the electrodes.The result is usually gas, the gradualdissolving of one electrode, and de-posits of metal ions on the other elec-trode. Obviously, these effects caneasily distort the results of the conduc-tivity measurement.

Fortunately, the above problems areeasily avoided by using alternatingcurrent instead of direct current. Inpractice, this minimizes the effects ofelectrolysis at the electrodes, providedthe frequency of the current is highenough. It seems that about 100 Hz isthe absolute minimum for such mea-surements, which means that the 0.5 -Hz signal produced in the switchingcircuit at the input of the present mon-itor is wide off the mark. To change theswitching frequency to about 100 Hz,the values of the timing components inthe oscillator are modified as follows:R1=f22=39 k52; C1=10 nF. Professionalinstruments of this type often use amuch higher switching frequency: upto 10 kHz!


800535 HARDWARE/ASSEMBLERCOURSE

PART 3: INTRODUCTION TO COMPARE/CA- U E U111 (CCU) ANDINT:RRUPTS

Since the CCU (compare/capture unit)of the 800535 is functionally related tointerrupts in general, these two sub-jects are discussed alongside eachother in the present course instalment.When used in capture mode, the CCUenables, for instance, accurate timemeasurements to be performed by soft-ware. Similarly, the compare modemay be used to program a generator forvariable pulsewidth signals. The timingof the CCU is arranged by Timer 2 inthe 800535. Some of the features ofTimer 2 will be discussed here. Only ahandful of components, and simpleprograms, are required to become fa-miliar with the ins and outs of theCCU. As usual, the relevant programsmay be found on your course disk.

The extended interruptsystemTo some of you, some interrupts mayalready be familiar, for instance, thoserelated to Timer 0 and Timer 1, and theexternal interrupts (P3.2=INTO andP3.3=INTI). From the 8051/80C32 as-sembler course, you may also remem-ber that individual interrupt eventscause bits in the special function regis-ter TCON to be set. Provided the rele-vant interrupt has been enabled bysetting the corresponding bits in theIEN register, an interrupt is then actu-ally generated. In the 800535, this sys-tem has been extended with a couple ofinterrupt sources. The extended archi-tecture is shown in Fig. 5. Special at-tention should be drawn to the newexternal interrupts IEX2 to IEX6,which correspond to port bits P1.0 toP1.4 (although differently numbered).As illustrated in Fig. 6, the interruptevent then sets the corresponding bit isthe IRCON register at address OCOH.Bits IEX2 to IEX6 are automaticallycleared when the interrupt routine isfinished. Alternatively, they may be setand reset via software. To be able toenable these interrupts, the relevantbits in the IENO or IEN1 register (seeFig. 7) must be set. Remember, to beable to enable interrupts at all, the EALbit (bit 7 in IENO) must be set.

Software by Dr. M. Ohsmann

Some of you may already have no- 800535. If one of these port lines is toticed that the port bits of Port 1 have a be used as an input (which includes itsnumber of additional functions in the use as an interrupt input), the output

1E0P3.2/INT 0TCON.0

TIMER 0TFO

Overflow

1E1P 3.3/INT 1 o).

TIMER 1

TCON .2

TF1Overflow

Receiver F

SERIAL PORTTransmitter It

TIMER 2

OverflowTF2

P1.5/T2EX EXF2EXEN2-I

A/D-Converter

P1 4/1NT 2

PI 0/INT3/CCO

°Y.T2CON 5

Compare 0

T2CON 6

Compare 1

PI 1/INT4/CC1

PI 2/INTS/CC2

Compare 2

Compare 3

P1.3/INT6/CC3

IADC

IEX2

IEX4

I EX5

IEX6

0

2

920152-14

Fig. 5. Schematic showing the interrupt sources which can be used with the 800535.


34 COMPUTERS AND MICROPROCESSORS

Special Function Register IRCON (Address OCOH)

0C7H 0C6H 0C5H 0C4H 0C3H 0C2H 0C1 H OCOH

OCOH EXF2 TF2 IEX6 IEX5 IEX4 IEX3 IEX2 IADC IRCON

Bit Function

IADC A/D converter interrupt request flag. Set by hardware at the endof a conversion. Must be cleared by software.

IEX2 External interrupt 2 edge flag. Set by hardware when externalinterrupt edge was detected or when a compare event occurred atpin 1.4/INT2#/CC4. Cleared when interrupt processed.

IEX3 External interrupt 3 edge flag. Set by hardware when externalinterrupt edge was detected or when a compare event occurred atpin 1.0/INT3#/CCO. Cleared when interrupt processed.

IEX4 External interrupt 4 edge flag. Set by hardware when externalinterrupt edge was detected or when a compare event occurred atpin 1.1/INT4/CC1. Cleared when interrupt processed.



TF2 Timer 2 overflow flag. Set by a timer 2 overflow. Must be clearedby software. If the timer 2 interrupt is enabled, TF2 =1 will causean interrupt.

EXF2 Timer 2 external reload flag. Set when a reload is caused by anegative transition on pin T2EX while EXEN2 =1. When the timer 2interrupt is enabled, EXF2 =1 will cause the CPU to vector thetimer 2 interrupt routine. Can be used as an additional externalinterrupt when the reload function is not used. EXF2 must becleared by software.

920152 - 15

Fig. 6. Interrupts cause certain bits in the IRCON register to be set.

state of the associated pin must beprogrammed as '1' (logic high).Fortunately, that is the default stateafter a reset, so no extra programming

is required. However, if the port waspreviously used as an output, it is rec-ommended to return the relevant pinsto 'input' (1) by explicit programming,

800535 PROGRAMMING

You need the following to be able tofollow the 800535 hardware/assemblercourse:

Hardware:- An 800535 single -board computer asdescribed in Elektor ElectronicsFebruary 1994.

- An IBM PC or compatible with a serialport on COM1: or COM2:.

Software:- Courseware disk (5.25 inch, 360KMSDOS format),

- EMON52 system EPROM, fitted on800535 SBC.

The courseware disk and EPROM areavailable as a set under order code 0221.The disk is also available separately underorder code 1811. For prices and orderinginformation, see page 70.

JOIN THE COURSE!

to make absolutely sure that they areinputs after a reset. That is also neces-sary if you want to use the alternativeoutput functions of these pins, for in-stance, if pulsewidth modulated sig-nals are generated (see exampleprogram 535XMP05.A51 on your disk).

The address vectors for differenttypes of interrupt routine are shown inFig. 8. As with the 80C32, we are facedwith a problem: since the monitorEPROM will normally reside at the ad -

Special Function Register IENO (Address 0A8H)

OAFH OAEH OADH OACH OABH OAAH 0A9H 0A8H

0A8H EAL ET2 ESO ET1 EX1 ETO J EXO

This bit is not used for interrupt control.

Special Function Register IEN1 (Address OB8H)

OBFH OBEH OBDH OBCH OBBH OBAH OB9H 0B8H

IENO OB8H EXEN2 EX6 EX5 EX4 EX3 EX2 EADC IEN1

This bit is not used for interrupt control.

Bit

EXO

Function

Enables or disables external interrupt 0.If EXO = 0, external interrupt 0 is disabled.

ETO Enables or disables the timer 0 overflow interrupt.If ETO =0. the timer 0 interrupt is disabled.

EX1 Enables or disables external interrupt 1.If EX1 = 0, external interrupt 1 is disabled

ET1 Enables or disables the timer 1 overflow interrupt.If ET1 =0, the timer 1 interrupt is disabled.

ESO Enables or disables the serial channel 0 interrupt.If ESO = 0, the serial channel 0 interrupt is disabled.

ET2 Enables or disables the timer 2 overflow or external reloadinterrupt. If ET2 = 0, the timer 2 interrupt is disabled.

EAL Enables or disables all interrupts. If EAL = 0, no interrupt will beacknowledged. It EAL = t, each interrupt source is individuallyenabled or disabled by setting or clearing its enable bit.

Bit Function

EADC Enables or disables the A D converter interruptIf EADC = 0, the AD converter interrupt is enabled.

EX2 Enables or disables external interrupt 2.capturecompareinterrupt 4. If EX2 = 0, external interrupt 2 is disabled.

EX3 Enables or disables external interrupt 3,capture compareinterrupt 0. If EX3 = 0, external interrupt 3 is disabled.

EX4 Enables or disables external interrupt 4,capture.'compareinterrupt 0. If EX4 0, external interrupt 4 is disabled.

EX5 Enables or disables external interrupt 5 capture' compareinterrupt 0. If EX5 = 0, external interrupt 5 is disabled.

EX6 Enables or disables external interrupt 6/capture/compareinterrupt 0. If EX6 =0, external interrupt 6 is disabled.

EXEN2 Exables or disables the timer 2 external reload interrupt.EXEN2 = 0 disables the timer 2 external reload interrupt.The external reload function is not affected by EXEN2.

920152 -29

Fig. 7. Registers IENO and IEN1 are used to enable interrupts.


800535 HARDWARE/ASSEMBLER COURSE - 3 El

Interrupt request flags Interrupt vector address Interrupt source

1E0 0003H External interrupt 0

TFO 000BH Timer overflow

E1 0013H External interrupt 1

TF1 001BH Timer 1 overflow

RIO TIO 0023H Serial channel 0

TF2 EXF2 002BH Timer 2 overflow ext. reload

IADC 0043H A D converter

lEX2 004BH External interrupt 2

IEX3 0053H External interrupt 3

IEX4 005BH External interrupt 4

IEX5 0063H External interrupt 5

IEX6 006BH External interrupt 6

RI1T11 0083H Serial channel 1

CTF 009BH Compare timer overflow

920152 - 16

Fig. 8. Overview of fixed interrupt vector addresses.

P1 7/T2

n

T210

T211

goGated Timer

Timer 2

T2 PS

Timer

TL2 TH2

4-

P1.5/T2EX

Sync

EXEN2

TF2

fosc,12

EXF2

1

Re-load

InterruptRequest

J

Fig. 9. Input circuit of counter/timer 2.

dresses shown in Fig. 8, the interruptroutines seem out of your control. Thisproblem is solved by the LINK mecha-nism provided by the EMON51 monitorEPROM, which allows the interruptroutines to be 'chained'.

EMON51 is capable of setting uplinks for 8031/8051 and 80C32 inter-

rupts only. By contrast, the new moni-tor, EMON52, handles all 800535 in-terrupts also. Consequently, you mustuse EMON52 instead of EMON51 if youwant to use the monitor to assist withprogramming interrupts which arespecific to the 800535. Since it was de-sired to enable readers in possession of

the 'old' monitor EPROM to follow thepresent course without problems,there are no example programs on thecourse disk that make use of the ex-tended interrupts offered by the800535. Nonetheless, some know-howon interrupts will be required to fullyunderstand the operation of Timer 2(fortunately, a corresponding interruptwas already foreseen in the 'old' moni-tor, EMON51).

Owing to lack of space, the interruptpriority assignment used in the800535 is not discussed in thiscourse. Details on this subject may befound in the Siemens/Intel datasheets.

Timer 2: the CCU coreBefore we run into a lot of confusion, itshould be made clear that the 8052and 8032 microcontrollers also sport a'Timer 2'. Timer 2 in the 800535, how-ever, works in a totally different way,because it is controlled by other bits inother SFRs. The 800535 is, therefore,not compatible with the 8052 in thisrespect. It is, however, compatible withthe 8051, simply because the latterdoes not have a Timer 2.

For now, let us concentrate onTimer 2 in the 800535. This is a 16 -bittimer consisting of SFRs TL2 (addressOCCH, LS counter byte) and TH2 (ad-dress OCDH, MS counter byte). Theclock signal for Timer 2 can be derivedfrom different signals. The input circuitis shown in Fig. 9. Figure 10 showsthe configuration of the timer in 're-load' mode, while Fig. 11 lists thefunction of the bits in the T2CON spe-cial function register (at addressOC8H), which serves to controlTimer 2. As can be deduced fromFig. 9, the timer clock signal can begenerated in four ways. The selection ismade by programming bits 1 (T2I1)and 0 (T2I0) in register T2CON.

1. If both bits are at 0, the counter(timer) stops, since it is no longer sup-plied with a clock signal.2 The bit combination 'O1' selects theso-called timer function, when the in-ternal clock is used to clock thecounter. The internal clock is thequartz crystal frequency divided by 12.Since a 12 -MHz quartz crystal is used,the internal clock is a 1 -MHz signal,but only if the available divide -by -twoprescaler is switched off (bit 7=T2PS=0in T2CON). If the prescaler is switchedon (by setting the T2PS bit), the inter-nal clock frequency is lowered to500 kHz.3. If bits T2I1 and T2I0 are given thevalue '10', the so-called counter func-tion is selected, when the signal ap-plied to the P1.7/T2 pin is used as aclock. That allows Timer 2 to be usedto count external events. The counter



8051Programming?

If you've tried this, you'll know whatit's like using 8051 assembler.Admittedly, given enough time and effort,even the impossible can be accomplished.But can your project afford to wait?Keil C51 is very simple to use and yet yieldsthe fastest and smallest code of any 8051 Ccompiler. With direct access to the 8051 cpuat a bit/register level in C, assemblerprogrammers feel instantly at home.

C51 Professional Developer's Kit Comprises:* Full ANSI C implementation for the 8051

family* Near -assembler code efficiency* Function -level optimisation* Extensions for 8005171800751* Small/Compact/Large/Banked memory support DScope5l+ cpu simulator/debugger* A51 macro assembler* 8051 Real Time Executive* Support from official C51 User Group* Free 8051 C Programmer's Handbook

To see how C51 takes the pain out of 8051programming, call now for our comprehensiveinformation pack including demonstrationversions of the compiler and debugger.

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800535 HARDWARE/ASSEMBLER COURSE - 3 Eg

T2EXP1.5

InputClock

TL2 TH2

',Mode 1

"Mode 0

Reload

CRCL CRCHTF2

EXEN2

EXF2

Timer 2- Interrupt

Request

Fig. 10. Timer 2 in reload mode.

Special Function Register T2CON

OCFH OCEH OCDH OCCH OCBH OCAH OC9H ()GBH

OCBH T2PS T2R1 1: T2R0 T2CM T2I1 T210 T2CON4_,z O/OZZL___

/ These bits are not used in controlling the CCU.

Timer 2 control register. Bit -addressable register which controls timer 2 function and

compare mode of registers CRC, CC1 to CC3.

Bit Function

T2I1 T2I0

0 0

0 1

1 0

1 1

Timer 2 input selectionNo input selected, timer 2 slotsTimer function, input frequency= fOSG 12 (T2PS = 0) or f(D8c24 (T2PS = 1)Counter function, external input signal at pin T2 -P1.7Gated timer function, input controlled by pin T2,R1.7

T2R1 T2R00 X

1 0

1 1

Timer 2 reload mode selectionReload disabledMode 0: auto -reload upon timer 2 overflow (TF2)Mode 1: reload upon falling edge at pin T2EX/P1.5

T2CM Compare mode bit for registers CRC, CC1 through CC3. When set,compare mode 1 is selected. T2CM = 0 selects compare mode 0.

T2PS Prescaler select bit. When set, timer 2 is clocked in the "timer" or"gated timer" function with 1 24 of the oscillator frequency.T2PS = 0 gates foss 12 to timer 2. T2PS must be 0 for thecounter operation of timer 2.

920152 - 19

Fig. 11. The functions of Timer 2 are controlled via bits in the T2CON register.

is clocked on the negative -going(falling) edge of the external signal. Itshould be noted, however, that thelogic state of pin P1.7 is detected onlyonce during every machine cycle.Consequently, the maximum countrate equals 500 kHz. Also, the 'low' and'high' times of the input signal musthave a minimum length of one ma-chine cycle, to enable a signal edge to

be detected. Remember, a machinecycle equals 12 times the quartz cycletime, i.e., one microsecond at thequartz frequency used on the 800535SBC.4. If T2I 1 and T210 are both at '1',Timer 2 is programmed to function as a'gated timer'. In this mode, too, the in-ternal clock (with or without the T2PSprescaler) is used to clock the timer.

However, the clock signal only reachesthe counter if P1.7 is at '1'. This modemay be used, for instance, to deter-mine the pulse/pause ratio of signals.That also concludes the discussion ofthe different types of signal that maybe used to clock Timer 2. The T2CM bit(bit 2 in T2CON) is skipped for the mo-ment, and we turn our attention tobits 3 and 4 in T2CON.

Timer 2 reloadA number of programming options areavailable to determine the programflow when Timer 2 overflows at itsmaximum counter state, OFFFFH, or65535. In any case, this event causesthe TF2 bit (bit 6 in the IRCON, seeFig. 6) to be set. What happens next isdetermined by the state of bit 4 (T2R1)and bit 3 (T2R0), which are both in theT2CON SFR. If T2R1 is at '0', the so-called reload mode is disabled, and thecounter simply starts at 0 again. ifT2R1 is at '1', Timer 2 is operated in re-load mode, in which bit T2R0 deter-mines when the counter is reloadedwith the value contained in the reloadregister pair CRCL-CRCH (compareFig. 10). In mode 0 (T2R0 = 0), thecounter is loaded after the overflow.The reload value is then contained inthe CRCL (LS byte; OCAH) and CRCH(MS byte; OCBH) register pair. If thepair contains, for example, the valueOFFFCH (-4), the counter countsOFFFFH, OFFFCH, OFFFDH, OFFFEH,OFFFFH, OFFFCH, and so on. If theT2R1 bit is at '1', the counter is re-loaded any time a negative pulse edgeis detected at pin P1.5. This option isparticularly useful if you want to syn-chronize the counter with an externalsignal. For instance, a phase controlcircuit may be realized by drivingpin P1.5 with a 50 -Hz signal derivedfrom the mains. This effectively syn-chronizes Timer 2 with the mains fre-quency. At a count rate of 1 MHz(internal clock used without theprescaler), that enables a phase con-trol circuit with a resolution of one mi-crosecond to be realized.

If bit EXEN2 (bit 7 in the IEN 1 regis-ter, see Fig. 7) is set, each reload sig-nal edge at P1.5 also causes bit EXF2(bit 7 in IRCON, see Fig. 6) to be set.This can be interrogated by software,while an interrupt may also be gener-ated by enabling the relevant interrupt.

Next time: in next month's final in-stalment of the course we will concludethe discussion of the CCU and theTimer 2 operation using a couple ofprogramming examples.


38

`STAMP' BASIC COMPUTER

It's small, easy to program, flown in from the States,affordable, based on a RISC processor, and a real block busterwhen it comes to developing turnkey software in less time thanyou ever dreamed possible. It's the wonderful stamp -sizedcomputer that runs BASIC. Real cute!

AT first glance, the Stamp may seemairly minimal - and in fact, it is,

hence its name. But, with softwarethat fully utilizes all available hard-ware, the Stamp gives you useful andpowerful features - without the cost ofhardware.

The Stamp has a size of about5x2.5 cm (2x1 in.), and consists of twomain components. The brain of theStamp is a PIC16C56 microcontrollerlrunning the PBASIC interpreter devel-oped by Parallax Inc. A 256 -byte EEP-ROM holds a tokenized version of yourBASIC program, which is read and exe-cuted by the interpreter contained inthe PIC. The remainder of the Stamp istaken up by a 4 -MHz resonator, a 5-Vregulator, and a 9-V PP3 battery clip.Also included is a small prototypingarea, which provides connection points

Sources: Parallax Inc. and K.H. Eichler (Wilke Technology).

ISJ

vcc

47K

{YRA2

RA3

16

4706

RAI ]

37C

e

RAO

OSC1 316RTCC162N3906

MCLR plc OSC2 32.2M C Vss 16C56 Vdd 13

6 XT 13

t RHO RB7

E RBI RB6

BROWNOUTRESET CIRCUIT --HE RB2 RB5

4 RB3 RB4

DATA

BUSY

4.7

CS Vcc

CLK93LC56 NC

DI ORG

DO Vss

10117 4 MHz

I I

9V in(BatteryOp)

LM2936

VI VOGND

Vec

T10µF

0

REGULATEDPOWER SUPPLY

0

O

5

3

USER -PROGRAMMABLE00 PORT

PCPROGRAMMINGCONNECTOR

94003211

Fig. 1. Schematic of the Stamp single -board BASIC computer.

for the Stamp's eight I/O lines, 5-Vsupply, unregulated supply, andground.

The BASIC Stamp is programmed inthe simple BASIC language. The lan-guage includes familiar instructionssuch as FOR...NEXT, IF...THEN, andGOTO, as well as SBC-specific instruc-tions such as SERIN (serial input) andBUTTON (button input). Each instruc-tion takes two or three bytes of EEP-ROM space, resulting in a maximumprogram size of 80 to 100 instructions.As for execution speed, programs runat the rate of about 2,000 instructionsper second.

To write programs for the Stamp, youwill need a Development Kit. The kit in-cludes editor software for a PC, a cableto connect the Stamp to the PC, oneBASIC Stamp, and a manual. By con-necting the Stamp to your PC's parallelport and then running the editor, youcan write BASIC programs and thendownload them to the Stamp. If you arefamiliar with the BASIC language, it is amatter of minutes before you have yourfirst program running. Furthermore, anumber of application notes are avail-able free of charge from Parallax Inc. tohelp you become acquainted with pro-gramming the computer.

It is possible to use the BASIC inter-preter developed by Parallax Inc. inyour own designs. This can be achievedby purchasing 'bare' interpreter chipsfrom Parallax Inc. at prices rangingfrom $5 (1,000 off) to $18 (one off). Addto that a 256-EEPROM, a 4 -MHz res-onator and a power supply, and youcan start using your own miniatureBASIC computer. Applications? Whatabout an LCD user -interface terminal,interfacing an A -D converter, a matrixkeypad in/LCD screen out circuit, aservo motor driver, a pulse meter, amorse code generator, an intelligentbattery charger, or a serial steppermotor controller? The list can be ex-tended to any length, depending onlyon your creativity.

Circuit descriptionFigure 1 shows the circuit diagram ofthe Stamp board supplied by ParallaxInc. as part of their Development Kit.The component count is, well, low! Thecomponent locations on the board areshown in Fig. 2.

The microcontroller used is aPIC16C56XT preloaded with Parallax'sPBASIC interpreter. The PIC devicealso contains an I/O port, a serial in-terface and a clock oscillator. The pro-gram memory is formed by a 93LC56


39

MS il-1111.111

N1d,

d00/ d( tek7,Increase yourelectronicsknow-howand skillsPractical creativity in electronicsThe speed and intensity with which elec-tronics penetrates our daily lives at home,at work, or in our car, tends to make usforget that we can use electronics cre-atively by building designs with a practi-cal application and having the satisfac-tion of a successfully finished project.Elektor Electronics, which is distributedall over the world, can help you achievethese goals. Throughout the year, themagazine features original constructionprojects, informative articles and newson the gamut of electronics, science &technology, book reviews and informa-tion on new products.

The value of an annual subscriptionIf you wish to increase your electronics know-how and skills, take out an annual

subscription to Elektor Electronics by filling in the order form on page 71 or writing ortelephoning to the address below. You will then not only

have the convenience of having the magazine delivered toyour home and the peace of mind that you will not miss any

issue, but you will also save money compared with buyingthe magazine from a bookstall: the price of a subscriptionin Britain for the 11 annually published issues is thesame as the average price of 10 issues bought from abookstall. Rates are shown on page 72.

World Wide Subscription Service Ltd,Unit 4, Gibbs Reed Farm,

Pashley Road, TICEHURST,East Sussex TN5 7HE, England

Telephone (0580) 200 657 (National)or +44 580 200 657 (International)

Fax (0580) 200 616 (National)or +44 580 200 616 (International)

go.21;:r.° N,Cd

RF Altentsw3/4

fef!!!!!te

Omocorei

aooance,Audion

NLECTRUNIN

40 COMPUTERS AND MICROPROCESSORS

9 -voltBatteryClips

5 -volt 4 MHz 3 -pinRegulator Resonator Header

C 11(14I, SIZE

(C) 99R Parallax In

PC>

C

C

C

C

00

BASI

C

C

C

r3C3C3CaCSTAMP

.590 0

00 0X100320 033o 0

yinO 0 0 0O 0 0 0O 0 0 0O 0 0 0O 0 0 0

400000035030000036000000,7000000

0 0 0 0 0 0G140

Mounting 256 -byte PIC16C56Holes EEPROM Microcontroller

PrototypingArea

940032.16

Fig. 2. Locations of the main components on the BASIC Stamp.

EEPROM which retains the BASIC pro-gram even in the absence of the supplyvoltage. The EEPROM has a storage ca-pacity of 256 bytes, allowing a programof between 80 and 100 lines of BASICto be stored.

An on -board low -drop 5-V voltageregulator allows the Stamp to be pow-ered from any d.c source with an out-put voltage between 6 V and about15 V. In most cases, a 9-V PP3 size bat-tery will be used to power the Stamp.

The schematic shows a power -downcircuit based on one transistor andthree resistors. Apart from ensuring agood reset no matter how long theStamp has been off, the reset circuitalso clears the PIC microcontrollerafter a 'brown -out'. A brown -out occurswhen the supply voltage drops below5 V, but not low enough to allow thechip's reset function to operate.

The Stamp offers a clever energy -saving power -down scheme which iscontrolled by three BASIC instructions:NAP, SLEEP and END. These allow theStamp to 'sleep' at a current consump-tion of about 20 pA, while all outputsretain their logic level.

The eight I/O lines may be used formany purposes, even for resistancemeasurement using the BASIC 'pot'command. Each I/O line is capable ofsupplying up to about 20 mA. How-ever, the total load on all lines may notexceed 40 mA.

Using the Stamp editorThe diskette in the Stamp DevelopmentKit contains a simple editor which runson a DOS PC. The editor offers the fol-lowing functions: Run, Load, Save andQuit. Once you have the editor run-ning, the screen is available to writeyour BASIC program. If you are readyto test it, download the program to theStamp using the ALT -R (Run) com-

mand. The BASIC program is compiledby the PC, and copied to the Stamp intokenized form via the PC's parallelprinter (Centronics) port. The progressof the download operation can beviewed as a horizontal bar, which alsoindicates the amount of EEPROMmemory space left in the Stamp.

If the program does not function asexpected, return to the editor, andchange the BASIC commands as re-quired. Simple word processing com-mands like cursor movement, copy,cut, paste and search/replace areavailable for that purpose. The syntaxand program formatting rules are ex-plained in detail in the manual thatcomes with the Stamp DevelopmentKit. To save you a lot of typing, the pro-gram disk in the kit also contains14 programs which belong with appli-cation notes published for the Stamp.

PBASIC command setThe PBASIC command set can be sub-divided into eleven groups:

1. Branching2. Looping3. Numerics4. Digital in/out5. Serial in/out6. Analogue in/out7. Sound8. EEPROM access9. Time10. Power control11. Program debugging

In addition to the commands availablemost BASIC dialects, there are a num-ber of Stamp -specific commands whichallow, for instance, an external circuitto generate analogue voltages, or mea-sure resistance values. Additionally,there are commands to generate tones,and to set up serial communication be-

tween a chain of Stamps or other ancil-lary circuits, in other words, a kind ofnetwork 'on a shoestring'.

As regards variables used in theBASIC programs, the following shouldbe observed:

the variables area is limited to16 bytes;

o of these, two bytes are required forthe I/O lines;

o the remaining 14 bytes may be used asword variables (W0 -W6) and byte vari-ables (BO -B13). Of these, BO and B1(WO) may be used as bit variables 0-15.

Of the two bytes used for the I/O lines,the first indicates the state of the rele-vant line (high or low), and the second,the direction (input or output). Thereare several ways of addressing individ-ual lines, for instance, by programmingPort.0, Pins.0 or PinO, Port.8, Dirs.0 orDirO. With the rest of the variables, itshould be noted that W6 is used as asoftware stack whenever GOSUB com-mands are executed.

The SYMBOL command enables youto assign names different from BO -B13and W0 -W6 to the variables. For in-stance:

symbol switch = pin0

Comments can be added to make theprogram more readable. They beginwith an apostrophe (`) and continue tothe end of the line. The well-knownREM command may be used as an al-ternative.

Very conveniently, labels may beused instead of line numbers to branchwithin the program. For instance:

loop: toggle pin0goto loop

Finally, as regards general formats, theeditor is case sensitive, except whenprocessing strings (such as "stamp").Multiple instructions and labels can becombined on the same line by separat-ing them with colons (:). For instance,

dirs = 255 : for b2 = 0 to 100 : pins =b2 : next

An example applicationThe following application note, origi-nally published by Parallax, Inc. as no.2, presents the hardware and softwarerequired to interface an 8 -bit serialanalogue -to -digital converter to theParallax BASIC Stamp. The applicationschematic is shown in Fig. 3.

The BASIC Stamp's instruction 'pot'performs a limited sort of analogue -to -digital conversion. It lets you interfacenearly any kind of resistive sensor tothe Stamp with a minimum of diffi-culty. However, many applications callfor a true voltage -mode analogue-to-


`STAMP' BASIC COMPUTER 41

=.0"."'''''8CS VCC ]-

2

0-5V in >--[

4

pier Pram Inco 0 0 o 0 o

poffICE

C I 1

E0L

BASIC STAMP

01

2

0O

vii.g.0 ADC CLIPc

Vin(-) DO

GND Vret 3 -

3080000006000000600000070000000 0 0

1-*AN--->- SERIAL1k OUT

940032-17

Fig. 3. Circuit to accompany AD_CONV.BAS.

' PROGRAM, ad conv.bas

BASIC Stamp program that uses the National ADC0831 to acquire analog data and outputit via RS -232.

Symbol

Symbol

Symbol

Symbol

Symbol

Symbol

CS

AD

CLK

S_out

data

setup: let pins = 255let dirs = 811111101

0

pinl

2

3

b0

b2

loop: gosub cony

serout S_out,N2400,(8b0,13,10)pause 2000

goto loop

c low CLK

low CS

pulsout CLK, 1

let data = 0

for i = 1 to 8

let data = data * 2

pulsout CLK, 1

let data = data + ADnext

high CS

return

' Pins high (deselect ADC).' S_out, CLK, CS outputs; AD input.

Get the data.

' Send data followed by a return and linefeed.' Wait 2 seconds' Do it forever.

Put clock line in starting state.Select ADC.

10 us clock pulse.

Clear data.

Eight data bits.

Perform shift left.

10 us clock pulse.

Put bit in LSB of data.

Do it again.

Deselect ADC when done.

940032-18

Fig. 4. Listing of AD_CONV.BAS.

digital converter (ADC). One that isparticularly suited to interfacing withthe Stamp is National Semiconductor'sADC0831.

Interfacing the ADC0831 requiresonly three input/output lines, and ofthese, two can be multiplexed withother functions (or additionalADC0831s). Only the chip -select (CS)pin requires a dedicated line. TheADC's range of input voltages is con-trolled by the VREF and VIN(-) pins. VREFsets the voltage at which the ADC willreturn a full-scale output of 255, whileVIN(_) sets the voltage that will return 0.

In the example application, VIN(_) is

at ground, and VREF is at +5 V; how-ever, these values can be as close to-gether as 1 V without harming thedevice's accuracy or linearity. You mayuse diode voltage references or trimpots to set these values.

The sample program is listed inFig. 4. It reads the voltage at the ADC'sinput pin every two seconds, and re-ports it to the PC via a 2400 -baud ser-ial connection. The subroutine 'cony'handles the details of getting data outof the ADC. It enables the ADC bypulling the CS line low, then pulses theclock (CLK) line to signal the beginningof a conversion. The program then en-

ters a loop in which it pulses CLK, getsthe bit on pin AD, adds it to the re-ceived byte, and shifts the bits of thereceived byte to the left. Since BASICtraditionally does not include bit shiftoperations, the program multiplies thebyte by two to perform the shift.

When all bits have been shifted intothe byte, the program turns off theADC by returning CS high. The sub-routine returns with the conversion re-sult in the variable 'data'. The wholeprocess takes about 20 milliseconds.

You can add more ADC0831s to thecircuit as follows: connect each addi-tional ADC to the same clock and datalines, but assign it a separate CS pin.Modify the 'cony' subroutine to takethe appropriate CS pin low when itneeds to acquire data from a particularADC. That's it!

The program may be downloadedfrom the Parallax Bulletin Board sys-tem in the USA under the file nameAD_CONV.BAS. You can reach the BBSat (+1) 916 624-7101.

Who, what, where?In addition to the BASIC StampDevelopment Kit sold by Parallax Inc.,Wilke Technology of Germany supply arange of products, including a com-piler, an extensive hardware develop-ment system, and different types ofStamp SBC. It should be noted thatthese products are aimed mainly at ad-vanced users, which is reflected by thecost. The hardware development sys-tem marketed by Wilke Technology ismuch more elaborate than theDevelopment Kit supplied by Parallax.

To request information, prices, ororder Stamp -related products, contact

Parallax Inc., 3805 Atherton Road,#102, Rocklin, CA 95765, U.S.A. Tel.(+1) 916 624-8333. Fax: (+1) 624-8003. BBS: (+1) 916 624-7107 (300-14,400 bps; no parity; 8 data bits; 1stop bit).

Wilke Technology products are avail-able fromWilke Technology, Postfach 1727,Krefelder Str. 147, D-5100 Aachen,Germany. Tel. (+49) 241 154071.Fax: (+49) 241 158475.

In Hungary, contactHumansoft,.Ltd., II -1149 Budapest,Angol u. 24/b, Hungary. Tel. (+36)1163 2879, fax: (+36) 1251 3673.

Further distributor information may beobtained from Parallax Inc.

Note:1. See also TIC programmer' in theMarch 1994 issue of ElektorElectronics.


42

FIGURING IT OUTPART 16 MORE ABOUT FOURIER

By Owen Bishop

This series is intended to help you with the quantitative aspects of electronic design:predicting currents, voltage, waveforms, and other aspects of the behaviour of circuits.

Our aim is to provide more than just a collection of rule -of -thumb formulas.We will explain the underlying electronic theory and, whenever

appropriate, render some insights into the mathematics involved.

Last month we described howthe Fourier series is used to

represent any periodic waveform.To recapitulate, the series con-sists of:

constant (d.c.) term

cosine terms

sine terms.The constant term and the coef-ficients of the cosine and sineterms are found by integration:

A =- ydt [Eq.123]27r

[Eq. 124]

1 2,ran= -11

-

Sy cos nt dt

1 rbn=g y sin nt dt

[Eq.125]

The constant term, which equalsthe average value ofthe variable(for example, voltage) duringone cycle, can sometimes be foundby geometrical means. We areoften able to simplify the inte-grations by using the standardintegrals given in Box 2 of Part 15.A frequent result of simplifica-tion is that the series for a givenwaveform has no cosine termsor no sine terms. Now we will lookat some further ways of simpli-fying the calculations.

Even functionsAn even function is one whichis symmetrical about the y-axis.It is as if the y-axis acts as amirror, reflecting the curve of thewaveform for positive values ofx on to the negative side of theaxis. Figure 131 shows someexamples of even functions.

Mathematically, we can expressthis by:

f (x) = f (-x).

If a waveform is an even func-tion, we can say, without anyneed for integrations, that:

it may or may not have a con-

Vt

stant term;it has cosine terms;it has no sine terms.An obvious example of an even

function is the cosine waveformof Fig. 131a, which has a cosineterm and no sine terms. Whetheror not it has a constant term de-pends on whether it is superim-

0

Fig. 131

Fig. 132

930010 - XVI - 131

930010 - XVI - 132

posed on a constant d.c. level(as, for example, is the wave-form of Fig. 131b). Ifyou find thata waveform is symmetrical aboutthe y-axis, you need not wastetime by trying to evaluate the in-tegral of Eq. 125.

Odd functionsThese are symmetrical aboutthe origin. If we imagine thecurve spun round through 180°around a centre located at theorigin, it comes to lie on itself.Figure 132 shows some odd func-tions. The characteristic featuresof an odd function are:

it has no constant term;it has no cosine terms;it has sine terms.In short, an odd function has

only sine terms. Since it is sym-metrical about the origin, it cannever have a constant term.Between them, even and oddfunctions cover most ofthe wave-forms we are likely to meet inelectronics, but there are a fewother recognizable types of wave-form that yield series with dis-tinctive features. The next twoheadings deal with these.

Half -wave inversionIn Fig. 133, the waveform be-tween t = 0 and t = n is repeated,but inverted, between t = TE andt = 2n. This is known as half -wave inversion. The Fourierseries for such a waveform has

no constant term;no even cosine terms;no even sine terms.The effects of half -wave in-

version and the kinds of sym-metry are cumulative. The wave-form of Fig. 133a has odd sym-metry and half -wave inversion.Because it has odd symmetry(and also because it has half-


FIGURING IT OUT - PART 16 43

wave inversion), it has no con-stant term. Because it has oddsymmetry, it has no cosine terms.Because it has half -wave sym-metry, it has no even sine terms.We are left with a series thathas only odd sine terms. By con-trast, the waveform of Fig. 133bhas even symmetry and half -wave inversion. It therefore hasno constant term and no sineterms. It has only odd cosineterms.

Half -wave repetitionThe waveform of Fig. 134 is re-peated in the second half of thecycle. For such a waveform, theseries has:

possibly a constant term;no odd consine terms;no odd sine terms.The example here has a con-

stant term. Removing the con-stant term of this example wouldshift the curve down, giving itodd symmetry. It therefore hasonly even sine terms. This ruledoes not necessarily eliminatethe need to calculate all threeofAo, an, and bn, but does at leastprovide a check that your calcu-lations are correct.

Square wavesThe waveforms we have analysedso far have all been continuouswithin the period 0 to 2n. Nowwe will tackle a waveform thathas an abrupt change of level dur-ing the cycle. Figure 135 is asquare wave with a mark:spaceratio of 1. We have arbitrarilytaken the 'high' level to be 3.This is a piecewise function and,to find the series, we have todeal with each part of the func-tion separately. First of all, theconstant term is the sum of twointegrals:

A0= -1 ft3dt+ 7cdt

1 r

In this example, the second in-tegral has zero value:

1Ao = 27z[3t]or +0

3=

2fr[ft- 0]= 1.5

This result could have more read-ily been obtained by inspectingthe graph and noting that the av-erage value of y is 1.5.

For the value of an we againintegrate for both parts of thewaveform:

Yt

0

yt

Fig. 133

930010 - XVI - 133

0TC

Fig. 134

Y=3 0<t<11Y=0 rz<t<211

3n

930010 -XVI- 134

Fig. 135

Fig. 136

2TC -Op930010 - XVI - 135

1 71.

an =- J 3 cos nt dt+011- 0

=3

[sin nap.'nit

=3

[sin nir]=0.9549sin nit

nit

But sin nn = 0 if n is an integer,making an = 0. This result meansthat there are no cosine terms.We could have told this at thestart because this is essentiallyan odd function, raised on a d.c.level of 1.5 (compare with Fig. 134).The constant term 1.5 simplyraises it above the x-axis. If theconstant term is ignored, so that,in effect, it is lowered until itpasses through the origin, it be-comes an odd function and hasonly sine terms.

Finally, we calculate bn:

bn =-1 13 sin nt dt+0

=-3

[cos nt]ornn

=-3

[cos nir-cos 0]nn

=-3

[cos nn -1]nit

There are two possibilities to beconsidered: when n is even, cos nn = 1,

which makes bn = 0; when n is odd, cos nit = -1,

in which event bn = 6 /nn=1.9099/n.The series has only odd cosine

terms. This, too, might have beenforeseen: when the waveform isshifted down to be symmetricalabout the x-axis, it has half -waveinversion, resulting in it havingno even terms. Writing out theseries:

y =1.5+ 1.9099(sin t+ sin3

3t +

sin 5t sin 7t sin 9f+...)

5 7 9

Figure 136 shows the graph ofthe series when taken to the 10thharmonic (n = 9).

Frequency spectrumAnother way of looking at a se-ries is to plot its frequency spec-trum. This has a vertical linefor each frequency, the heightof the line being proportional tothe amplitude of the frequency.In the series we have just cal-culated, the amplitude of thefundamental is 1.9099. The am-plitude of the 1st harmonic is1.9099/3 = 0.6366. Figure 137shows the plot of the fundamental


44 GENERAL INTEREST

and first 10 harmonics. The evenones are missing and the am-plitude of the odd ones falls awayfairly rapidly. Last month weanalysed a sawtooth wave beforeand after passing it through ahigh-pass filter. Figure138 showsthe frequency spectra of thesewaveforms; the effect of filter-ing is obvious.

Pulse waveformsIn Fig.139 we have a pulse wave-form, which is another exampleof a piecewise function. This isanalysed in a similar way to the1:1 square wave above. If weshift it n/10 to the left, the pulsebegins at-n/10 and ends at n/ 10.It is now an even function, soits Fourier series has no sineterms. By inspection, we can tellthat Ao = 0.3.

For the cosine terms:

1 /10ari = - 3 cos nt dt

--r/10

10=-1[-sin nar Irc n3 717E -nom

= [sin -sinnor 10 10

6 . tin= sin

10

=1.9099 sin(nn/10)

n

If n = 1, then sin(nn/10) = 0.3090;for n = 2 to 9, we obtain 0.5878,08090, and so on to 0.3090. Whenn = 10, sin(nn/10) = 0, so thereis no 9th harmonic. The sequenceof values is repeated for n = 11to 20, except that they are neg-ative. From n = 21 onwards thewhole sequence repeats, but weare not concerned with harmon-ics of such a high order.

Written out as far as the 2ndharmonic, the series looks likethis:

y=0.3+1.9099 (0.3090 sin tsin 2f

2

+0.8090 sin3t + )3

Simplifying the coefficients,by dividing by n (1, 2, 3, ...):

y =0.3+1.9099 (0.3090 sin t

+0.2939 sin 2t

+0.2700 sin 3t+...)

The values of sin(nn/10) increasefor the first few terms, so thispartly offsets the effect of divid-ing them successively by 1, 2,3, .... In consequence, the firstfew harmonics are almost as strong

as the fundamental as shown inFig. 140. This is plotted as faras the 10th harmonic (there is no9th). Compared with the squarewave of Fig. 135, as shown inFig. 137, there is much less fall-off in the lower harmonics of

2-

this pulse wave. This propertyof pulse waveforms is made useof in synthesizer circuits. A pulsewaveform is a strong source ofharmonics which can be filtered(formant filtering) to adjust theirproportions until the resultant

10-

5-

A

I

0.5 -

Fig. 137

UNFILTERED

FILTERED

9 n930010 -XVI- 137

n

1 2 4 5 6 7 8 9 10n

930010-XVI-139

Fig. 138

Y=3 O<t<i1,=0 5<t<25

03-A

0.2 -

0.1 -

Fig. 139

2 3 4

Fig. 140

t

930010 - XVI -139

I8 9 10 11-, n

930010 -XVI- 1.

sound has the timbre of a givenmusical instrument. Althoughthe amplitude of the higher har-monics falls offmore significantly,the limits of audibility are reachedaround the 5th harmonic. However,there is an increase of ampli-tude from the 10th to the 14th,which has an amplitude almostequal to that of the 7th harmonic.This illustrates the fact that un-expectedly strong harmonics maybe present in pulse signals.

Other periodsThe formulae described above allrefer to a waveform in whichone cycle takes 2n seconds. Inother words, the angular veloc-ity is unity. This corresponds toa frequency of 0.159 Hz. This israther lower than many of thefrequencies we meet in electroniccircuits and, even though theanalysis of different waveformsis independent of the frequencyof the fundamental, there aremany instances when we wantto know the Fourier coefficientsfora frequency that is not 0.159 Hz.Adapting the formulae to an-other frequency is just a matterof altering the time -scale.

The equations relating an-gular velocity, co, frequency, f, andperiod (length of cycle), T, are:

= 27c/TOr

T = 2n1

The phase angle at any giventime t is cot. The Fourier seriesin these conditions is the sameas before, except that we replacet in the cosine and sine termsby cat. Conversely, making co = 1restores the terms to their orig-inal form.

The formulae for the constantterm is:

1 1k=-T oF(t)dt

The formulae for the coefficientsare:

2an=, - F(t)cosnokdto

bri=-2T il(t) sin n cot dt0

These show the limits of inte-gration running from 0 to T, butthey can also run from -T/2 toT/2if this makes the integration anyeasier.

We will derive the Fourierseries for the square wave ofFig. 135, but with a period of


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0.01 s., corresponding to a fre-quency of 100 Hz. At 100 Hz,T = 0.001 and w = 2n/0.001= 628.3 rad.

The average value of y is notaffected by the frequency, soA0 = 1.5 as before. Also, as be-fore, we recognize this to be anodd function, so that a, = 0 andthere are no cosine terms. Forthe sine terms:

2 0.005ki= 3 sin ncat dt

0.01 o3

(cos nn -1)0. 005nw

If n is even, cos nit = 1, andb, = 0. There are no even terms.If n is odd, cos nn = -1 andb, = 6/0.005n w = 1.9099/n.

The series is exactly the sameas that for the square wave ofFig. 135, except that, insteadof sin t, sin 3t, ..., we now havesin wt, sin 3c, ... The graph ofthe series has the same shape,except that the scale on thex-axis runs from 0 to 0.001 s.Thus, all that we have said aboutwaveforms with a period of 2napplies with little modificationto periods of other lengths.

By contrast with the slowfall -off of harmonics in pulsewaveforms, there are other wave-forms in which the rate of fall-offis rapid. An example is shownin Fig. 141. This is the waveformof a half -wave rectified alter-nating voltage. The coefficientsfor the cosine terms are given by

VIDEO HEADS

I II

the equation2a =

n n -(1-n2)

The denominator contains n2and successive coefficients (thereare even terms only) are: 2/3n,2/15n, 2/35n, 2/63n, ... The se -

SPEAKERS CONNECTORS

II I

I I; I

I el Ii

ries has only a single sine term,so this has no effect on the rapidfall -off of the harmonics.

At this point we leave thediscussion ofthe Fourier Series,having shown how to analysemany of the most commonly oc-curring waveforms. Often the in -

Fig. 141

Fig. 142

33001 - XVI - 142

SEMICONDUCTORS

II I

45

tegrations are long, and proneto error, especially with the fre-quent changes in sign that re-sult from integrating functionscontaining sines and cosines. Therules we have discussed willhelp by eliminating the needfor some of the integrations. Whenyou have arrived at the equationfor a series, plotting it with agraphic calculator is a rapid meansof checking that it is essentiallycorrect.

Test yourself1. lb what categories do the wave-

forms of Fig. 142 each be-long. In each case state whatelements you would expect tofind in their Fourier series.

2. A sawtooth waveform withperiod 2n is defined by theseequations:y = 3t 0<t<ny = 3t -3n p<t<271Derive its Fourier series.

Answers toTest yourself (Part 15)a0 = 2Tc; = 0; bn= -4/a.Series is: y = 2n-4sint-2sin2t

-1.333 sin3t-sin4t...Filtered signal is

/tout = -3.988sin(t-0.0808)-1.975sin(2t-0.1608)-1.297sin(3t-0.2358)-0.9525sin(4t-0.3098)


46

LOW -VOLTAGE MONITORDesign by J. Ruiters

During experimental work, the power supply is often variableor derived from a mains adaptor. In such cases, it is important

to eliminate the risk of damaging ICs through overvoltage.The unit described in this article is intended for monitoringthe supply voltage when the standard multimeter is already

in use for other purposes.

Alsthough electronic circuits on testhould preferably be powered by a

supply whose output voltage can be setaccurately and is provided with a currentlimiting facility, in practice this is not al-ways available. If a quickly put togethersupply is used on the test bench or withexperimental work, ideally, two multi -meters should be to hand: one for moni-toring the supply voltage and the otherfor carrying out measurements on the cir-cuit. If only one is available, the presentmonitor may prove useful.

The monitor is suitable for use withvoltages in the ranges 2.0-6.0 V, 4.5-5.5 V,3.0-15.0 V and one set by the user be-tween 0 V and 14 V.

Apart from monitoring direct voltages,the unit may be used to react to suddenchanges in voltages. This is, for instance,convenient for checking equipment thathas a difficult -to -find, randomly occur-ring fault. Such equipment may be leftoperating on the test bench with the moni-tor attached. If a sudden change in volt-age occurs in it, the monitor may indi-cate this by emitting a squeak from anoptional buzzer.

The circuitThe circuit-see Fig. 1-is based on twocomparators: ICI, and IC lb. These mea-sure the input voltage on terminals A andB against accurately known potentials.These reference voltages are provided byvariable zener diode DI and potential di-viders R8 -P2, R9 -P3 and R2 -R7. The zenervoltage can be set accurately to exactly2.5 V with P1. Resistor R1 is the standardseries resistor that prevents the zenerdrawing too large a current.

Divider chain R2 -R7 provides a num-ber of fixed reference voltages, which areselected by SI.

Dividers Rg-P2 and R9 -P3 provide the(variable) reference voltage that is deter-mined by the user.

If the voltage on terminals A and B risesabove, or falls below, set values, D2 (red)or D3 (green) lights respectively. If theinput voltage lies between two set values,the two diodes light simultaneously. It isalso possible to use buzzers as indica-tors, which eliminates the need to keep

an eye on the LEDs.The input voltage is also applied to po-

tential divider R10 -R11 (1:6). The (scaleddown) input voltage is applied to the non -inverting (+) input of IC la and to the in-verting (-) input of IC1b. When the poten-tial at one terminal of the comparatorsbecomes larger or smaller than that atthe other input, the relevant comparatorchanges state. At that instant, the volt-age at terminal A is exactly six times thereference voltage applied to the other ter-minal of the toggling comparator by S 1 .

To give a range over which the inputvoltage may be considered safe, the corn-

BABA50k 50kMT MT

10k

LM336-2.5906081X - 11

Fig. 1. Circuit diagram of the low -voltage monitor.

4V5...15V


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48 LOW -VOLTAGE MONITOR

O

IN '6' 0to

DO I 0

+0 01R13 10--9.-201R9

0

LaEll

Q-1 ru

I4 LW

Fig. 2. Printed -circuit board for thelow -voltage monitor

parator stages are designed in a mannerwhich prevents their toggling at the sameinput level. This range with S1 in position1 is 2.0-6.0 V (HC/HCU ICs); in position2, 4.5-5.5 V (HCT/TTL ICs); in position3, 3.0-15.0 V (4xxx ICs); and in position4 as required by the user between 0 V and14 V. Note that section Sib provides theupper reference voltages, and S a, thelower ones.

Since the input voltage is applied todifferent terminals of the comparators,these stages behave in opposite ways. Forinstance, with high input voltages, theoutput of IC la is high and that of IC ib islow, whereas with low input voltages, theoutput of ICI, is low and that of IC lb ishigh.

The divergent behaviour of the com-parators affects the operation of indicatornetworks T1 -D2 and T2 -D3. When one ofthe comparator outputs is high, the as-sociated transistor conducts, whereuponthe allied LED lights. This means that ifthe input voltage is higher than the upperreference voltage D2 lights and when it isbelow the lower reference voltage, D3 lights.When the level of the input voltage liesbetween the two reference potentials, bothLEDs light.

If it is desired to have an audible indi-cation of voltage changes, a 0.1-1 pF ca-pacitor (not electrolytic) must be con-nected in series with terminal A. The inputis then taken from the equipment on testas stated earlier. The buzzer should beconnected to the monitor circuit as shownin Fig. 4.

3.9V...4.7V

906081X - 12

ConstructionThe monitor is best built on the printed -circuit board shown in Fig. 2 (not avail-able ready made). The completed proto-type is shown in Fig. 3.

The monitor may be constructed as astand-alone unit or be built into an ex-isting equipment. In the former case, theenclosure may be given a front panel asshown in Fig. 5 (not available ready made,but the picture may be photocopied andglued behind a transparent panel).

If a buzzer is used and it is desired thatthis squeaks when the input voltage istoo high, connect its +ve terminal to 'x' inFig. 4, and its -ve terminal to ground. Asecond buzzer may be connected to indi-cate too low input voltages: this shouldbe connected between 'y' and ground. Thezener diode in series with the buzzer pre-vents its squeaking faintly when the rel-evant transistor conducts.

It is also possible to use only one biwhich should be connected via a bridgerectifier to 'x' and 'y'. In this case, thebuzzer is silent when the input voltagelies in the safe range, but it squeaks whenthe input goes outside this range.

It is advisable to use small buzzers thatdraw a current of not more than 1-3 mA(at 5-12 V).

The monitor may be powered conve-niently from a mains adaptor. The supplyvoltage may be 4.5-15 V. At 9 V, it drawsa current of about 30 mA.

When the construction has been com-pleted, adjust P1 to obtain a voltage of ex-actly 2.500 V, measured with a digital

le>4XXX HCT

EXTRA 4010.10/ HCIFICU

VOLTAGE MONITOR

IOW

e CP

Fig. 3. Photograph of the prototypelow -voltage monitor.

Fig. 4. Various ways of connecting an op-tional buzzer (or buzzers) to the monitor.

Fig. 5. Suggested front panel for thelow -voltage monitor.



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voltmeter, across DI (or P1). Make surethat the type coding of DI is LM336-2.5.

Range 4 is set with a variable powersupply, set to the desired voltage, and avoltmeter across input terminals A andB. Adjust P3 until the green LED just goesout and P2 until the red LED just goesout.

Finally, make sure that terminal A isclearly marked + and terminal B -. Polarityreversal would not do the comparatorsany good.

Parts list

Resistors:R1 = 1 IcS2

R2 = 1.5 k52, 1%R3 = 84.5 K2, 1%R4, R6 = 165 Q, 1%R5 = 249 Q, 1%R7 = 332 Q, 1%R8, = 2.2 lic2R10=11k52, 1%Ril = 2.21 k1-2, 1%R12, R13 = 100R14 = 47 kflR15, R16 = 10 k52R17, R18 = 1.5 k52P1 = 10 k52, 10 turns presetP2, P3 = 50 li52, 10 turns preset

Capacitors:C1 = 10 pF, 16 V

Semiconductors:T1, T2, = BC547BDi = LM336-2.5D2 = LED, redD3 = LED, green

Integrated circuits:ICI = LM393

Miscellaneous:S1= 2 -pole, 6 -position rotary switch, with

suitable knobEnclosure (if required) 120x65x40 mm

(43/4x21/2x11/2 in), e.g. Bopla E430BB- represented in UK by Phoenix MecanoLtd, telephone (0296) 398 853.


50

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Some years ago, the Macintosh had thedisadvantage of being more expensivethan MS-DOS machines. Over the past fewyears, Macintosh prices have, however,come tumbling down and they are now com-parable to, and in some case even lowerthan, those of MS-DOS computers of sim-ilar performance.

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seen considerable development over recentyears, one the one hand because of the dif-ficulties related to filtering and on theother because of the possibilities offeredby new semicondctors.

The first chapter of the book describesthe principles of inverters and explains thechoice and weighing of topics. In the fol-lowing chapters, the different types of in-verter are described in great detail with anemphasis on their application in practice.Springer-Verlag London Ltd, Sweet AppleHouse, Catteshall Road, GodalmingGU7 3DJ. Telephone 0483 418 800.

DATA ACQUISITION AND PROCESSCONTROL WITH THE M68HC11MICROCONTROLLERBy Frederick F. Driscoll, Robert F.Coughlin and Robert S. VillanucciISBN 0-02-330555-XPrice 25.95 (hard cover)The real fun in using microcontrollersstarts when you are able to do somethinguseful with such a 'beast'.

This book should be of special interestto readers who have constructed the 68HC11processor board described in the April1994 issue of Elektor Electronics.

The book addresses the entire scope ofusing the 68HC11 microprocessor for in-strumentation and control systems. Variousskills must be mastered before such ap-plications can be made to work as theyshould. The book shows how these manyskills can be organized effectively by em-ploying an engineering design procedurewith practical application examples.

The first four chapters of the book aredevoted to the MC68HC11 microcontrollerand an Evaluation Board system obtainedfrom Motorola. This system runs a moni-tor program called Buffalo 1, which standsfor Bit User Fast Friendly Aid to LogicalOperation. Buffalo offers a number of fairlybasic commands like moving blocks ofmemory, calling addresses, go, input/out-put, block fill, etc., but also more advancedstuff like an assembler/disassembler, anddebug functions like trace and breakpoint.

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The last three chapters deal extensivelywith data acquisition and control problemswith complete hardware and software de-signs given, and each problem explained.The example programs are presented inthe form of neatly formatted assemblylanguage listings with plenty of commentto assist in understanding the operation.

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. _

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USING THE DOUBLE BALANCEDMIXER (DBM)

In radio frequency electronics a mixer is a non-linear circuit or device that permits frequencyconversion by the process of heterodyning. Mixers are used in the 'front-end' of the most

common form of radio, the superheterodyne (regardless of wave band), in certain electronicinstruments and in certain measurement schemes (receiver dynamic range, oscillator phase

noise, etc). This article looks at a very popular mixer circuit, the double balanced type.

THE block diagram for a basic mixersystem is shown in Fig. 1; this dia-

gram is generic in form, but also repre-sents the front-end of superheterodyneradio receivers. The mixer has threeports: F1 receives a low-level signal, andwould correspond to the RF input fromthe aerial in radio receivers; F2 is a high-level signal, and corresponds to the localoscillator (LO) in superhet radios; and F3is the resultant mixer product (corre-sponding to the intermediate fre-quency or 'IF' in superhet radios). Thesefrequencies are related by:

F,= mF, ± nF, (1)

Where:F1, F2 and F3 are as described above;m and n are counting numbers (zero plusintegers 0, 1, 2, 3, ...)

In any given system, m and n can bezero, or any integer, but in practical cir-cuits it is common to consider only thefirst, second and third order products.For sake of simplicity, let us consider afirst -order circuit (m=n=1). Such a mixerwould output four frequencies: F1, F2, F3a= F, + F2, and Fab = F1 - F2. In terms of aradio receiver, these frequencies repre-sent the RF input signal, the local oscil-lator signal, the sum IF and thedifference IF. In radios, it is commonpractice to select either sum or differenceIF by filtering, and rejecting all others.

There are a number of different typesof mixer circuit, but only a few differentclasses: single -ended, single balanced(or simply 'balanced') and double bal-anced. Most low-cost superheterodyneradio receivers use single -ended mixers,although a few of the more costly 'com-munications receiver' models use singlyor doublee balanced mixers for improvedperformance. This article focusses on thedouble balanced mixer (DBM) because itoffers superior performance over theother forms, but is not as well known inelectronic hobby circles.One of the advantages of the DBM overthe other forms of mixer is that it sup -

By Joseph J. Carr, B.Sc., M.S.E.E.

Fig. 1. Block diagram of a mixer used as a frequency converter.

presses F1 and F2 components of the out-put signal, passing only the sum and dif-ference signals. In a radio receiver usinga DBM, the IF filtering and amplifierwould only have to contend with sum anddifference IF frequencies, and not botherwith the LO and RF signals. This effect isseen in DBM specifications as the port -

to -port isolation figure, which can reach30 to 60 dB depending on DBM model.

A diplexer stage is shown in Fig. 1,and is used to absorb unwanted mixerproducts, and pass desired frequencies.These frequency selective circuits arediscussed below.

A post -amplifier stage is typically

Double BalancedMixer Low -Pass

Filter

L2 C4

High -PassFilter

XL 5052

C3

10n

toPost -Amp

940004 - 12

Fig. 2. Diplexer circuit based on low-pass and high-pass filters.


USING THE DOUBLE BALANCED MIXER (DBM) esincluded because the insertion loss ofmost passive DBMs is considerable (5 to12 dB). The purpose of the amplifier is tomake up for the loss of signal level in themixing process. Some active DBMs, inci-dentally, have a conversion gain fig-ure, not a loss. For example, the popularSignetics NE602 device offers 20 dB ofconversion gain.'

Diplexer circuitsThe RF mixer is like most RF circuits inthat it wants to be terminated in itscharacteristic impedance. Otherwise, astanding wave ratio (SWR) problem willresult, causing signal loss and otherproblems. In addition, certain passiveDBMs (of which, more below) will notwork well if improperly terminated. Anumber of different diplexer circuits areknown, but two of the most popular areshown in Figs. 2 and 3.

A diplexer has two jobs: 1) it absorbsundesired mixer output signals, so theyare not reflected back into the mixer, and2) it transmits desired signals to the out-put. In Fig. 2, these goals are met withtwo different LC networks; a high-passfilter and a low-pass filter. The assump-tion in this circuit is that the differenceIF is desired, so a high-pass filter with acut-off above the difference IF is used toshunt the sum IF (plus and LO and RFsignals that survived the DBM process)to a dummy load (R,). The dummy loadshown in Fig. 2 is set to 50 Q becausethat is the most common system imped-ance for RF circuits (in practice, a 51-aresistor might be used). The dummy loadresistor can be a Y4 -watt unit in most low-level cases, but regardless of power levelit must be a noninductive type (e.g. car-bon composition or metal film).

The inductor (L,) and capacitor (C1)values in the high pass filter are de-signed to have a 50-a reactance at the IFfrequency. These values can be calcu-lated from:

50QL= (2)

2 n F3

C-27cF3(5052)

(3)

Where L is in henrys, C is in farads, andF, is in hertz.

The low-pass filter transmits the de-sired difference IF frequency to the out-put, rejecting everything else. Like thehigh-pass filter, the L and C elements ofthis filter are designed to have reac-tances of 50 Q at the difference IF fre-quency.

Recently I built a sweep generator tofacilitate an high performance AM band(540-1700 KHz) receiver that I am de-signing. The sweeper circuit is a varactortuned VCO driven with a 45 -Hz sawtoothwave. The swept oscillator is hetero-dyned against a 14 -MHz crystal oscilla-

Because C, -L, are shunted across the sig-nal line, it will short out all but the reso-nant frequency.

In direct conversion receivers, a mixeris used to down convert CW and SSB sig-nals directly to audio by setting F2 closeto F,, without using an IF amplifierchain. In those receivers it is commonpractice to build a diplexer similar toFig. 4. Capacitor C, passes high frequen-cies (which are RF), and they are ab-sorbed in a 50-Q dummy load. Thelow -frequency audio signals (300 to3,000 Hz) are passed by a 50-a low-passfilter consisting of L,, L,, L3, R2 and C2.

Fig. 3. Diplexer circuit based on series andparallel resonant circuits. JFET and MOSFET DBMs

tor, producing difference frequencieswhich can be tuned to either 455 KHz(my selected IF), or any frequency in theAM band. My diplexer unit consists oftwo 3,000-KHz Butterworth filters, onehigh-pass and the other low-pass; eachfilter consists of five reactance elements.The high-pass filter was terminated in a50-Q dummy load made by parallellingtwo 100-a metal film resistors (whichwere hand -selected for the correct value).The low-pass filter was terminated in apost amplifier with a 50-a input imped-ance.

Another popular diplexer circuit isshown in Fig. 3. This circuit consists of aparallel resonant 50-a tank circuit (C, -L,), and a series resonant 50-Q tank cir-cuit (C, -L,). The series resonant circuitpasses its resonant frequency while re-jecting all others because its impedanceis low at resonance and high at other fre-quencies. Alternatively, the parallel res-onant tank circuit offers a highimpedance to its resonant frequency, anda low impedance to all other frequencies.

Junction field effect transistors (JFETs)and metal oxide field effect transistors(MOSFETs) can be arranged in a ringcircuit that provides good double bal-anced mixer operation. Figure 5 shows acircuit that is based on JFET devices.Although discrete JFETs such asMPF102 or its equivalents can be used inthis circuit with success, performance isgenerally better if the devices arematched, or are part of a single IC device(e.g., the U350 IC). With due attention tolayout and input/output balancing, thecircuit is capable of better than 30 dBport -to -port isolation over an octave (2:1)frequency change.

The inputs and output of this circuitare based on broadband RF transform-ers. These transformers are bifilar andtrifilar wound on toroidal cores. Theinput circuit consists of two bifilarwound impedance transformers (Tr, andTr2). The LO and output circuits are trifi-lar wound RF transformers. Part of theoutput circuit includes a pair of low-passfilters which also serve to transform the1.5 to 2 kQ impedance of the JFET de -

Mixer

L1

tL0

VFO

Tune

3mH9

C1

100n

R1

C:a

L2

R2

C2 C3 AF

6µ4Iµ8[1-0

27mHL3

1 18mH

940004 - 14

Fig. 4. Diplexer for a direct conversion receiver. Note: R2 changed to 50 ohms if L2 is ideal.


54 COMPONENTS

Fig. 5. DBM circuit based on JFET transistors.

vices to 50 Q. As a result of the neededimpedance transformation, the filtersmust be designed with different R, andRout characteristics, and that fact compli-cates the use of look -up tables (whichwould be permitted if the input and out-put resistances were equal).

Double balanced diodemixer circuitsOne of the most easily realized doublebalanced circuits, whether homebrew orcommercial, is the circuit of Fig. 6. Thiscircuit uses a diode ring mixer and bal-anced input, output and LO ports. It iscapable of 30 to 60 dB of port -to -port iso-lation, yet is reasonably well-behaved in

Fig. 6. Diode double balanced mixer.

practical circuits. DBMs such as Fig. 6have been used by electronic hobbyistsand radio amateurs in a wide variety ofprojects from direct conversion receiversto single sideband transmitters andhigh-performance shortwave receivers.With proper design, a single DBM can bemade to operate over an extremely widefrequency range; several models claimoperation from 1 to 500 MHz, with IFoutputs from d.c. to 500 MHz.

The diodes (D, through D4) can be or-dinary silicon VHF/UHF diodes such as1N914 or 1N4148. However, superiorperformance is expected when Schottkyhot -carrier diodes, such as 1N5820through 1N5822 are used instead.Whatever diode is selected, all four de-vices should be matched. The bestmatching of silicon diodes is achieved bycomparison on a curve tracer, but failingthat there should at least be a matchedforward/reverse resistance reading.Schottky hot -carrier diodes can bematched by ensuring that the selecteddiodes have the same forward voltagedrop when biased to a forward current of5 to 10 mA.

Figure 7a shows the internal cir-cuitry for a very popular commercialdiode DBM device, the Mini -CircuitsSRA-1 and SBL-1 series; a typicalSRA/SBL package is shown in Fig. 7b.

These devices offer good performance,and are widely available to hobbyists andradio amateur builders. Some partshouses sell them at retail, as does Mini -Circuits [P.O. Box 166, Brooklyn, NY,11235, USA: phone 714-934-4500]2. I donot know the amount of their minimumorder, but I have had Mini -Circuits inthe USA respond to $25 orders on severaloccasions ... which is certainly more rea-sonable than other companies.

The packages for the SRA/SBL de-vices are similar, being of the order of20 mm long with 5 -mm pin spacing. Theprincipal difference between the pack-ages for SRA and SBL devices is in theheight. In these packages, pin no. 1 is de-noted by a blue bead insulator aroundthe pin. Other pins are connected to thecase or have a green (or other colour)bead insulator. Also, the `MCL' logo onthe top can be used to locate pin 1: the`M' of the logo is directly over pin 1.Table 1 shows the characteristics of sev-eral DBMs in the SRA and SBL series,while Table 2 shows the pin assign-ments for the same devices.

In the standard series of devices, theRF input can accommodate signals up to+1 dBm (1.26 mW into 50 Q), while theLO input must see a +7 dBm (5-mW) sig-nal level for proper operation. Given the50-a input impedance of all ports of theSRA/SBL devices, the RF signal levelmust be kept below 700 mVpp, while theLO wants to see 1400 mVpp. It is essen-tial that the LO level be maintainedacross the band of interest, or else mix-ing operation will suffer. Although thedevice will work down to +5 dBm, a greatincrease in spurious output and lessport -to -port isolation is found. Spectrumanalyzer plots of the output signal at lowLO drive levels show considerable secondand third -order distortion products.

Note the IF output of the SRA/SBL de -

Fig. 7. (a) Mini -Circuits SRA/SBL seriesDBMs; (b) typical Mini -Circuits DBMpackage.



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56 COMPONENTS

Fig. 8. Waveforms from a circuit using theMini -Circuits DBM: (a) improperlyterminated; (b) with part of diplexerdisconnected; (c) output waveform whendiplexer is connected.

vices. Although some models in the se-ries use a single IF output pin, most ofthese devices use two pins (3 and 4), andthese must be connected together exter-nally for the device to work.

As is true with most DBMs, and alldiode ring DBM circuits, the SRA/SBLdevices are sensitive to the load imped-ance at the IF output. Good mixing, andfreedom from the LO/RF feedthroughproblem, occurs when the mixer looksinto a low-VSWR load. For this reason, agood diplexer circuit is required at theoutput. In experiments, I have foundthat unterminated SBL-1-1 mixers pro-duce nearly linear mixing when not prop-erly terminated...and that is not what isdesired in a frequency converter.

The effects of the termination imped-ance on the operation of the diode DBMcircuit are shown in Fig. 8. The oscillo-scope photo in Fig. 8a shows the mixer

Type No LO/RF (MHz) IF (MHz) Mid -Band Loss (dB)

SRA-1 0,5-500 DC -500 5.5-7.0

SRA-1TX 0.5-500 DC -500 5.5-7.0

SRA-1W 1-750 DC -750 5.5-7.5

SRA-1-1 0.1-500 DC -500 5.5-7.6

SRA-2 1-1000 0.5-500 5,5-7.5SBL-1 1-500 DC -500 5.5-7.0

SBL-1X 10-1000 5-500 6.0-7.5

SBL-1Z 10-1000 DC -500 6.5-7,5SBL-1-1 0.1-400 DC -400 5.5-7.0

SBL-3 0.025-200 DC -200 5.5-7.5

Table 1. Main specifications of some commonly found diode double balanced mixers.

DBM

RF C33

4SRA-1

SBL-1 8+1dBm 10n

2 15 116I 7

LO[)+7dBm

1210n

Diplexer

L2* L3* C5 IFFOC6

IIMM

Cl0n

X C1' 5130

C

R1

*C4

X c5 552

*see text

940004 - 18

Fig. 9. Typical circuit using the Mini -Circuits SRA/SBL devices.

output directly at pins 3 and 4 of an SBL-1-1. Note that it is a complex waveformof mixed signals, and reflects the factthat the mixer is not properly termi-nated. The waveform at Fig. 8b wastaken at the output of the low-pass filterwhen the high-pass filter and its associ-ated dummy load was disconnected. AtFig. 8c is the resultant when properlymatched high pass (and dummy load)and low pass filters were in operation.The waveform was a nearly clean sinewave of 455 KHz. Another waveform, notshown, was obtained when there was nohigh pass filter, but the DBM was termi-nated in a resistance matched to its char-

acteristic impedance and a low pass fil-ter. It was a distorted sinewave, and re-flected the fact that other products werepresent in the output signal.

Figure 9 shows a typical SRA/SBLcircuit: RF drive (+1 dBm) is applied topin 1, and the +7 dBm LO signal is ap-plied to pin 8. The IF signal is outputthrough pins 3 and 4, which are strappedtogether. All other pins (2, 5, 6 and 7) aregrounded.

The diplexer circuit consists of a high-pass filter (C1 -L1) terminated into a 50-52dummy load for the unwanted frequen-cies, and a low-pass filter (L2 -L3 -C4) forthe desired frequencies. All capacitors

Type LO IF GND Case GND

SRA-1 8 3,4 2,5,6,7 2

SRA-1TX 3,4 2,5,6,7 2

SRA-1-1 8 3,4 2,5,6,7 2

SRA-1W 8 3,4 2,5,6,7 2,5,6,7SRA-2 8 3,4 1 2,5,6,7 2,5,6,7SRA-3 8 3,4 2,5,6,7 2SBL-1 8 1 3,4 2,5,6,7SBL-1-1 8 1 3,4 2,5,6,7SBL-3 8 1 3,4 2,5,6,7

Table 2. Pin function overview for diode DBMs.


ElUSING THE DOUBLE BALANCED MIXER (DBM)

a -OUT + OUT

+CARRIER

IN PUTL 0

- IN

BIAS

IN

GAINADJ

U

b

+ IN

GAIN ADJ

GAIN ADJ

- IN

BIAS

+ OUT

N.C.

CINDEX TAB

- CARRIERINPUT

+ CARRIERINPUT

940004 - 19a

U -

N.C.

- OUT

- CARRIERINPUT

N.C.

+ CARRIERINPUT

940004 - 19b

+ OUT - IN

BIAS

Bottom View

GAIN ADJ

GAIN ADJ

940004 - 19c

Fig. 10. (a) Internal circuitry for the LM1496DBM; (b) DIP package for the LM1496; (c)metal can package for the LM1496.

and inductors are selected to have a reac-tance of 50 f2 at the IF frequency.

Sometimes 1 -dB resistor n -pad atten-uators are used at the inputs and the IFoutput of the DBM. In some cases, theinput attenuators are needed to preventoverload of the DBM (overload causesspurious product frequencies to be gener-ated, and may cause destruction of thedevice). In other cases, the circuit de-signer is attempting to 'swamp out' theeffects of source or load impedance varia-tions. Although this method works, it isbetter to design the circuit to be insensi-tive to such fluctuations, rather than touse a swamping attenuator. The reasonis that the resistive attenuator causes asignal loss and adds to the noise gener-

LO

1--) C-1

0-1110n

C2

O -H10n

RF

R3

8200

R4

O1.0

R6

C4

100n

7

R7 1 ,1£1

1100n

niV

:00n

5

R1

5100

R2C3

1100n

+ C IN

-C IN

BIAS

+ OUT

+ IN

MC1496G

IN

V - GA

- OUT

GA

6

C5INIm*

9

10 2R5

477,17

3

O

*see text

Tr1

12V

O

IF

-C)=MI

940004 - 20

Fig. 11. Mixer circuit using the LM1496.

ated in the circuit (no resistor can be to-tally noise free). A good alternative is touse a stable amplifier with 50 f2 inputand output impedances, and that is notitself sensitive to impedance variation, toisolate the DBM.

Mini -Circuits devices related to theSRA-1 and SBL-1 incorporate MAR -x se-ries MMIC amplifiers internal to theDBM. One series of devices places theamplifier in the LO circuit, so that muchlower levels of LO signal will provideproper mixing. Another series places theamplifier in the IF output port. This am-plifier accomplishes two things: it makesup for the inherent loss of the mixer andit provides greater freedom from loadvariations that can affect the regularSRA/SBL devices.

Bipolar transconductancecell DBMsActive mixers made from bipolar silicontransistors formed into Gilbert transcon-ductance cell circuits are also easilyavailable. Perhaps the two most commondevices are the Signetics NE602 deviceand the LM1496 device (Maplin cata-logue no. QH47B, p. 463 in 1993 edition).

The NE602 was discussed extensivelyin Ref. 1, to which the reader is referredfor details on input, output and LO con-figurations.

The LM1496 device is shown inFigs. 10a, 10b and 10c. Figure 10ashows the internal circuitry, whileFigs. 10b and 10c show the DIP andmetal can packages, respectively. Pins 7and 8 form the local oscillator (or 'carrier'

in communications terminology) input,while pins 1 and 4 form the RF input.These push-pull inputs are also some-times labelled 'high level signal' (7 and 8)and 'low level signal' (1 and 4) inputs.D.c. bias (pin 5) and gain adjustment(pins 2 and 3) are also provided.

Figure 11 shows the basic LM1496mixer circuit in which the RF and carrierinputs are connected in the single -endedconfiguration. The respective signals areapplied to the input pins through d.c.blocking capacitors C1 and C2; the alter-nate pin inputs in both cases are by-passed to ground through capacitors C3and C4.

The output network consists of a 9:1broadband RF transformer that com-bines the two outputs, and reduces theirimpedance to 50 f2. The primary of thetransformer is resonated to the IF fre-quency by capacitor C5.

Figure 12 shows a circuit that usesthe LM1496 device to generate doublesideband suppressed carrier (DSSC) sig-nals. When followed by a 2.5 to 3-KHzbandpass filter, which is off -set from theIF frequency, this circuit will also gener-ate single sideband (SSB) signals. Incommon practice, a crystal oscillator willgenerate the carrier signal ( Uc), whilethe audio stages produce the modulatingsignal (Um) from an audio oscillator ormicrophone input stage. I once saw a cir-cuit that is very similar to this one in asignal generator/test set used to serviceboth amateur radio and marine HF-SSBradio transceivers. It was the signalsource to test the receiver sections of thetransceivers. The carrier was set to


58 USING THE DOUBLE BALANCED MIXER (DBM)

10k

20k(Carrier Null)

100

10k

® 12V

1k

470

8

10+ C IN

C IN + OUT

GA

MC1496+ IN

GA

- OUTINV - BIAS

14 5

100n

_--0411111111111111111111--0

0 8V

cn

2

12 0-U 0

940004 - 21

Fig. 12. Double sideband suppressed carrier (DSSC) generator circuit using the LM1496.

9 MHz, and both lower sideband (LSB)and upper sideband (USB) KVG crystalfilters were used to select the desiredsideband. An alternate scheme which ischeaper uses a single 9 -MHz crystal fil-ter, but two different crystals at frequen-cies either side of the crystal passband.One crystal would generate the USB sig-nal, while the other would generate the

LSB signal.For single sideband to be useful it has

to be demodulated to recover the audiomodulation. The circuit of Fig. 13 will dothat job nicely. It uses an LM1496 DBMas a product detector. This type of de-tector works on CW, SSB and DSB sig-nals (all three require a local oscillatorinjection signal), and produces the audio

Local Carrier

0

SSB

0-Hi

8

10

T

+ C IN

C IN

+ IN

+ OUT

GA

MC1496

INV-

GA

- OUT

BIAS

12V

6

2

14

8V

OD

940004 - 22

0

resultant from heterodyning the localcarrier signal against the SSB IF signalin the receiver. All SSB receivers usesome form of product detector at the endof the IF chain, and many of them usethe LM1496 device in a circuit similar toFig. 13.

ConclusionDouble balanced mixer circuits work bet-ter than most other mixer circuits inradio receivers, SSB transmitters/re-ceivers, instrumentation and measure-ment situations. They are easy to use inmost cases, and if properly designed intoa circuit yield good results with mini-mum effort.

References:1. 'NE602 primer', Joseph J. Carr,Elektor Electronics January 1992, pp. 20-25.2. In the UK, contact Dale ElectronicsLtd., Camberley, Surrey, tel. (025) 2835094.

Fig. 13. Single-sideband/CW product detector for receiver using the LM1496.



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XT KEYBOARDS Mixed types, some returns, some good, someforeign etc but all good for spares! Price is £2 each REF:MAG2P6or 4 for £6 REF: MAG8P4PC CASES Again mixed types so you take a chance next one offthe pile £12 REF:MAG12 or two the same for £20 REF: MAG20P4COMMODORE MICRODRIVE SYSTEM mini storagedevice for C64's 4 times faster than disc drives, 10 times fasterthan tapes. Complete unit just £12 REF:MAG12P1SCHOOL STRIPPERS We have quite a few of the aboveunits which are 'returns as they are quite comprehensive unitsthey could be used for other projects etc. Let us know how many youneed at just 50p a unit (minimum 10).HEADPHONES 16P These are ex Virgin Atlantic. You can have8 pairs for £2 REF: MAG2P8PROXIMITY SENSORS These are small PCB's with what looklike a source and sensor LED on one end and lots of components onthe rest of the PCB. Complete with fly leads. Pack of 5£3 REF: MAG:3P5 or 20 for £8 REF: MAG8P4SNOOPERS EAR? Original made to dip over the earpiece oftelephone to amplify the sound -it also works quite well on the cablerunning along the wall! Price is £5 REF: MAG5P7DOS PACKS Microsoft version 3.3 or higher complete with allmanuals or price just £5 REF: MAG5P8 Worth it just for the verycomprehensive manual! 5.25' only.DOS PACK Microsoft version 5 Original software but no manu-als hence only £3 REF: MAG3P6 5.25' only.FOREIGN DOS 3.3-German,Frenchttalian etc £2 a pack withmanual. 5.25' only. REF:MAG2P9CTM644 COLOUR MONITOR. Madetowork with the CPC464home computer. Standard RGB input so will work with other ma-chines. Refurbished £59.00 REF:MAG59PIR DETECTOR Made by famous UK alarm manufacturer theseare hi spec, long range internal units. 12v operation. Slight marks oncase and unboxed (although brand new) £8 REF: MAG8P5WINDUP SOLAR POWERED RADIO AM/FM radio completewith hand charger and solar panel! £14 REF: MAG14P1COMMODORE 64 TAPE DRIVES Customer returns at £4REF: MAG4P9 Fully tested and working units are£12 REF: MAG12P5

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REMOTE CONTROL PCB These am receiver boards forgarage door opening systems. You may have another use? £4 eaREF: MAG4P5

6.x12. AMORPHOUS SOLAR PANEL 12v 155x310mm130mA. Bargain price just £5.99 ea REF MAG6P12.FIBRE OPTIC CABLE BUMPER PACK 10 metres for £4.99ref MAG5P13 ideal for experimenters! 30 mfor£12.99 ref MAG13P1LOPTX Line output transformers believed to be for hi res colourmonitors but useful for getting high voltages frcei low ones! £2 eachREF: MAG2P12 bumper pack of 10 for £12 REF: MAG12P3.

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REF: MAG50



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Television: the basics

TSOUND -TO -LIGHT

UNIT

Although huge monitors are quite common in today's partybunkers, clubs and discotheques, the idea of using a TV setinstead of the more usual set of coloured lamps is quite novel.Here, a circuit is described to produce playful light effects onthe telly.

From an idea by B. Willaert

rrHE TV sound -to light unit de -1 scribed in this article may be driven

with a line signal or a signal picked upby a microphone. Depending on thespectral composition of the input sig-nal (bass, mid -range, treble), the cir-cuit sends a signal to the red, green orblue (R, G, B) input on the SCARTsocket of a TV set. This causes the TVscreen to go red, green or blue, orblends of these primary colours if theinput signal contains two or threestrong components in the respectivefrequency ranges. This means that theoperation of the TV sound -to -light unitis, in principle, identical to that of a'conventional' unit with three lamps.As an unusual feature, however, thepresent unit enables colours to bemixed.

glass face

Fig. 1. The perceived colour of a picture ele-ment is created by blending the primarycolours, red, green and blue, at the rightratio. The correct colour is obtained by firingelectrons at phosphor particles at the insideof the picture tube.

Before looking at the design of the TVsound -to -light unit, a brief recap isgiven of the operation of the TV system.The screen of a colour TV may be com-pared with a painter's palette with onlythe three primary colours on it: red (R),green (G) and blue (B). Any colour canbe made by mixing the RGB compo-nents at certain ratios.

A TV set obviously does not usepaint to mix colours. Instead, the pri-mary colours are mixed using electronbeams. The principle is illustrated inFig. 1. Each primary colour has itsown electron gun which 'fires' a verynarrow beam in the direction of the in-side surface of the TV picture. Thethree beams converge at the so-calledshadow mask at the inside of the pic-ture tube. The mask is a thin platewith masses of small holes which passthe three beams. When the beamsleave the holes in the shadow mask,they arrive on a layer of phosphor par-ticles which covers the inside of thepicture tube. Each beams 'hits' its ownphosphor type. The phosphor particleslight up when 'bombarded' with elec-trons, and so visualize the colours red,green and blue.

Since the three tiny light spots ineach pixel are very close together, theviewer perceives a dot with a certaincolour blend rather than three individ-ual primary colours. In this way, eachpicture element Cpixell is providedwith the correct colour information,and the entire picture is built up pixel -by -pixel.

The received TV signal contains,among others, information on the mix-ture ratio of the R, G and B signals.This information is received in com-pacted form, and decoded inside theTV set to yield the three primarycolours. Most modern TV sets have aSCART socket (also called Peritel orEuro A/V), which allows the RGB am-plifiers and associated electron guns inthe set to be driven with external sig-nals. And that, you guessed it, is ex-actly what the present circuit does.

Block diagramThe basic structure of the TV sound -to -light unit is shown in Fig. 2. As withan 'ordinary' sound -to -light unit, theinput signal is obtained either from a`line' connection (say, the mixing con-sole output) or a microphone. The sen-sitivity of the circuit is adjustable bysetting the gain of the input amplifier.

The amplified audio signal is fed tothree filter sections: a low-pass filter, aband-pass filter and a high-pass filter.These filters extract the bass, mid-range and treble information from theinput signal. The filter output signals


TV SOUND -TO -LIGHT UNIT 63

4060

013

05

04

06

0 PO 03

a.f.signal

Vsensitivity

low-pass filter

-*OwnIII-

band-pass filter

high-pass filter

synchronization

synchronization

signal

SCARTconnection

936038X - 12

Fig. 2. Most functions of the TV sound -to -light unit may be found in any conventional sound -to -light unit based on lamps. The difference, however, is the TV interface, which consists ofRGB driver stages and a synchronisation control circuit.

= imaging electron beam

- - 4- - = flyback electron beam936038X - 13

Fig. 3. The flyback (retrace) beam isquenched to avoid unwanted horizontal anddiagonal lines on the TV screen.

then drive the RGB inputs of the TV.Low frequencies cause the screen to gored, while mid -range and high compo-nents turn it green or blue respectively.

The block diagram also shows a syn-chronisation sub -circuit. This serves toensure that every picture line has theright length (approx. 64 ps), and thatthe retrace (or 'flyback') beam is

5V

RIM

K1

09

07

08

RESET

PI

PO

PO

2

3

Cl

-II33p IX1O100p

X1 = 4MHz

TLC274

/A VA LI LI LI

Pit] rill;

C4

II470n

( HP )-6.

C9 C11MIM

1001100 100n

R17 R19 C6 C7

1.--110n In

K3+9V...+12V

IC1

7805

5V

131...D55x 1N4148

BC547B

BC547B

C13 De 10V R25T4

C16 D10 1 R28

470n

IC1 IC2C23

100n

BC557B

BC557B

BC557B

R32 I ±1R33

IC2 = TLC274

BC547BBC557B

EL C

AUDIO4

SYNC -4.

K2SCART

9360380 14

R34

Fig. 4. Circuit diagram of the TV sound -to -light unit. The circuit takes its input signal either from a microphone or a line connection. A crystaloscillator is used to ensure the correct picture line length of 64 us (including the synchronisation pulse).


64 GENERAL INTEREST

quenched. As illustrated in Fig. 3, theelectron beam makes a scanning move-ment across the screen. During the re-trace period, the beam is quenched(switched off) to avoid unwanted lines,both horizontally and diagonally, beingwritten on to the screen.

Practical circuitAlthough the circuit diagram in Fig. 4

looks complex at first glance, the func-tions of the various sub -circuits areeasily recognized from the block dia-gram discussed above.

The audio signal is picked up by mi-crophone Mic1, and fed to the input ofa simple preamplifier stage based onopamp IC2b. Alternatively, the inputsignal may be applied directly via 'line'socket K1. The amplification of IC2bmay be set to a value between 0.02 and

4:11>ici

1.wiKep,1 ti

1911EM1113111allial

-drI T6

Fig. 5. Track layout (direct reading) and component overlay of the circuit board for the TVsound -to -light unit (PCB available ready-made through the Readers Services).

20. The preamplifier output signal isapplied to a combined filter, which di-vides the signal into low, mid -rangeand high components. The high fre-quencies leave the filter via pin 1 ofIC2a. The mid -range signals are foundat pin 14 of IC2d, and the low frequen-cies, at pin 8 of IC2,-

Next, the three components are ap-plied to three identical drivers, T4, T5and T6. Each signal is first rectified

Resistors:R1;R39 = 2kt/2R2 = 220kilR3,R5-R9,R28,R33 = 1041R4,R16,R17,R21,R22,R23 = 56kf/R10,R26,R29,R32,938 = 3900R11. 330kS1R12,R14,R15 = 141R13 221Q.

R18,R20 = 150k0R19 = 47 k52R24,R27,R30 = 1MS2R25 = 5kL16R31 = 15k5/R34 -R37 = 8251P1 = 470162 logarithmic

Capacitors:C1 = 33pFC2 = 100pFC3,C11,C12,C20,C21,C23 = 100nFC4,C5,C15 = 470nFC6 = 10nFC7,C8 = 1nFC9,C10,C22 = 100pF 10V radialC13 = 1pF MKTC14 = 22pF 10V radialC16,C18,C24 = 10pF 10V radialC17 = 220nFC19 = 100pF 40V radial

Semiconductors:D1 -D11 = 1N4148D12 = 1N4001D13 = LED 3mm redT1,T2 == BC547BT3 -T6 = BC557BIC1 = 4060IC2 = TLC274IC3 . 7805

Semiconductors:K1 = Cinch socket.K2 = 21 -way SCART socket, PCB

mount, angled pins.K3 = Mains adapter socket, PCB

mount.X1 = 4MHz quartz crystal.Midi = Electret microphone.Case: e.g., ESM EM14/03.Printed circuit board 936038 (see page70).


TV SOUND -TO -LIGHT UNIT 65

5V

936038X - 15

Fig. 6. Alternative connection schematic fortwo -wire electret microphones.

and smoothed by two diodes and a ca-pacitor (for instance, D7, D8 and C14),so that each driver is supplied with aclean direct voltage. The resistoracross each smoothing capacitor (forinstance, R24) enables the capacitorvoltage to decrease after a short whileafter the input signal has disappeared.This is done to give the sound -to -lightunit a fairly 'calm' behaviour, avoidinga too fast response to sound changes.The output signal of each driver tran-sistor is sent to the respective RGBinput via a current limiting resistor of82 Q.

The circuit diagram shows that theRGB driver transistors are supplied viaa series transistor, T3, which acts as aswitch, and so enables a simple kind ofsynchronisation to be realized. Theswitch is closed for 60 ps, which corre-sponds to the length of a picture line.Each period of 60 ps is headed by asynchronisation pulse of 4 ps, whichserves to inform the TV that a new lineis about to be written. The synchroni-sation pulse is sent to the TV set viaR34 and the respective pin on theSCART socket. To make sure that eachline period has a total length of 64 ps,the switching signals are derived froma crystal oscillator with associated di-vider, IC1. The 4 -MHz quartz clock sig-nal is divided by 256 (28), which givesa line frequency of 15.625 Hz, corre-sponding to a period of 64 ps.

Finally, the circuit is powered by amains adaptor with a direct outputvoltage between 9 V and 12 V. Theadaptor output voltage is steppeddown to 5 V by regulator IC3.

ConstructionThe artwork of the printed circuitboard designed for the TV sound -to -light unit is given in Fig. 5. This boardis available ready-made through theReaders Services.

Fig. 7. Fully populated circuit board.

Fig. 8. Prototype of the TV sound -to -light unit mounted into a plastic enclosure.

Start the construction by fitting allwire links, then the IC sockets. Soldercarefully to avoid a long fault-findingsession later. Next, fit all other parts,keeping the larger ones (for instance,the SCART socket and potentiometerP1) till the last. The SCART socket isfirst secured to the PCB by inserting itsplastic fixing pins into the two holes inthe PCB. Next, solder the socket pins.

Resistor R39 is not fitted on to theboard, but connected to the electretmicrophone as a 'flying' part. If the mi-crophone is a type with three termi-nals, it is connected as shown by the

circuit diagram. If you happen to havea two -terminal type, connect it asshown in Fig. 6. If you wish to use theline input only, Mic1 and R39 may, ofcourse, be omitted.

The board is ready for fitting into asuitable enclosure after it has beenpopulated (Fig. 7), and the solder workcarefully inspected. The prototypeshown in Fig. 8 should give you an im-pression of how we did the finishingtouch to the unit. The design of a frontpanel for the TV sound -to -light unitmay be copied from Fig. 9.

Connect the unit to the mains adap-


66 GENERAL INTEREST

936038X - F

Fig. 9. Suggested front panel design.

Fig. 10. The sound -to -light unit is connectedto the TV set via a ready-made SCART cable.

tor, taking good care to observe the po-larity of the d.c. supply voltage. Thecircuit is protected against reversesupply voltages by diode D12. If every-thing is in order, the 'power' LEDshould light after connecting the mains

adaptor.Next, connect the circuit to the TV

set via ready-made SCART cable(Fig. 10). The pinning of the SCARTplugs on the cable, and that of thesocket on the TV, is shown in Fig. 11.Also connect the microphone, or theline input signal.

Switch the TV to external A/V, andadjust the input sensitivity of thesound -to -light unit until the desired vi-sual effect is achieved.

Some experimentsA few suggestions are given for those ofyou who wish to adapt the circuit topersonal requirements. The responseof the circuit to changes in the inputsignal may be speeded up by decreas-ing the values of capacitors C14, C16and C18. Note, however, that thiscauses a slightly blurred picture, and

SCARTconnector 1

SCARTconnector 2

14 14

15 15

16 16

17 17

18 18

SCART socket(soldering side) screen

2 4 6 8 10 12 14 16 18 20

1 3 5 7 9 11 13 15 17 19

SCART plug(soldering side) screen

-(21

1 3 5 7 9 11 13 15 17 19111111111111111111112 4 6 8 10 12 14 16 18 20

21

936038X -16

unclear colour transitions. Similarly,the response of the circuit is sloweddown by increasing the values of theabove capacitors.

The 'low' frequency limit of the filterin the unit may be lowered by changingR18 and R20 into, for instance, 220 kit,and R19 into 100 k.S2. This modificationcauses the circuit to respond strongerto the lowest frequency components,and less to high -frequency compo-nents. To achieve a better separation ofthe low, middle and high components,the value of R19 may be lowered to22 kt2, while C6 is changed into 22 nF.

Fig. 11. Want to make a SCART cable yourself? Here are the plug and socket connections.


67

Books from Elektor Electronics (Publishing)

The following books are currently available:301 Circuits £9.95 $14.50302 Circuits £9.95 $14.50

303 Circuits £10.95 $17.90304 Circuits £12-95 $23.95305 Circuits (published in April 1994) £14.95 $27.70SMT Projects £ 9.95 $14.50Microprocessor Data Book £10.95 $19.90Data Sheet Book 2 £9.95 $18.50Data Book 3: Peripheral Chips £10.95 $19.95Data Book 4: Peripheral Chips £10.95 $19.95Data Book 5: Application Notes £10.95 $19.95

How to order:UK and Overseas private customers (NOTin USA and Canada) from:Elektor Electronics (Publishing)PO Box 1414 Dorchester, England DT2 8YHTelephone (0305) 250 995Fax: (0305) 250 996

UK and Overseas bookshops, schools,colleges, universities and bulk orders

(NOT in USA and Canada) from:Gazelle Book Services LtdFalcon House, Queen Square, Lancaster,England 1LA1 1RNTelephone (0524) 68765Fax: (0524) 63232

USA and Canada ONLY from:Old Colony Sound - please see order formon page 71 for details

SWITCHBOARDSwitchboard allows alt PRIVATE READERS ofElektor Electronics one FREE advertisementof up to 108 characters, including spaces,commas, numerals, etc., per month.

Write the advertisement. which MUSTrelate to electronics, in the coupon on thispage; it MUST INCLUDE a private telephonenumber or name and address; post officeboxes are NOT acceptable.

Elektor Electronics (Publishing) can not ac-cept responsibility for any correspondence ortransaction as a result of a free advertisementor of any inaccuracy in the text of such an ad-vertisement.

Advertisements will be placed in the orderin which they are received.

Elektor Electronics (Publishing) reservethe right to refuse advertisements withoutgiving reasons or without returning them.

FOR SALE. Cheap component packs. SendSAE for list to A. Tearle, 5 Springfield Close,Ramsgate, Kent CT11 7BQ.

WANTED. Manuals/information on ZortechC++ compiler/workbench/debugger, etc. Pleasering (0255) 473 547.

FOR SALE. Range of components, incl. 8051micros, steppers, PSUs, etc, at very low cost.Please ring (0533) 537 269.

WANTED. Elektor Electronics Feb, Mar, Apr

1990, Feb, Mar, May1991, Mar, July/Aug 1992.Ring Tony on (0458) 831 444.

FOR SALE.Voltage, current monitors; data log-ging on site or remote; can be used for almostanything. Also remote datalogger 32 inputs; willrun off car battery; incl. software £ 80.RingRobin on (0268) 524 968.

FOR SALE. Comtronics 1.2 m dish c/w polarmount and stand: £ 150. Also 90 cm fixed £40.Please call (0727) 833 839.

FOR SALE. All LF150A power amp PCBscomplete (cannot faultfind). Any reasonable offeraccepted. Ring 091 528 3122.

WANTED. Sage Supermos 1/2 amplifier mod-ules in very good working order. Please phoneJonathan on (0384) 296 823 after 7 p.m.

WANTED. Elektor Formant synthesizer, work-ing or not and boards and front panels, PSU,etc. to complete my project. Please ring (0726)66715.

WANTED. Coherent CW info & circuits fornovice. Please write to Owen Kilgour, ZL3TOW,Okari Road, Westport RD2, New Zealand.

FOR SALE. 5000 Series Tectronix storagescope, dual beam, dual time base, instructionand service manuals, £ 180. Ring Paul on(0562) 753 809.

HELP needed to solve problem with Elektor plot-ter: it will not work with 486 computer but works

VOUCHERThis voucher (original only; no

photocopies accepted) entitles theholder to 71/2% discount on thepurchase price of any Elektor

Electronics book listed in the adjacentbox. Two vouchers qualify for 15%

discount and three for 30%.More vouchers will be published in

forthcoming issues ofElektor Electronics

05/94

OK with 386 SX. Kaj Larsen, Gyvelvej 33,D-9560 Hadsund, Denmark.

FOR SALE. PicPro PIC programmer, £ 50ono. Phone Mike on (0285) 712 570.

Send this coupon toElektor Electronics (Publishing)

P.O. Box 1414Dorchester DT2 8YH

England

Block capitals please - one character to each box

ELEKTOR ELECTRONICS 05/94

Name and address MUST be given


68

ELECTRONICS SCENE

Surface mount crystal from IQDInternational Quartz Devices (IQD) has avail-able a surface mount version of the popularHC49/4H crystal. Designated the HC49/4HSMX, the new version has a footprint ofonly 4.9x13.4 mm and is 4.3 mm high.IQD Ltd, Crewkerne, Somerset TA18 7AR,England. Telephone (0460) 77155.

Embedded controller handbookMicrochip's new Embedded ControllerHandbook is packed with ideas and advicefor system designers and application pro-grammers. It contains almost a thousandpages of technical reference material andcovers the whole range of Microchip'sPIC16/17 8 -bit microcontrollers and spe-ciality non-volatile memory products.Arizona Microchip Technology Ltd,Unit 3, The Courtyard, Meadowbank,Furlong Road, Bourne End SL8 5AJ,England. Telephone (0628) 850 303.

Statek franchise for ACTQuartz crystal manufacturer and distributorACT (Advanced Crystal Technology) hassigned a franchise agreement with the spe-cialist quartz crystal firm, Statek Inc. ofOrange, California.ACT, 9 Kingfisher Court, HambridgeRoad, Newbury RG14 5SJ, England.Telephone (0635) 528 520.

Good for Europe?The Japanese government is about to aban-don Japan's analogue high -definition televisionsystem, which lags behind America's digi-tal technology despite decades of develop-ment. This decision makes it probable thata worldwide HDTV standard based onAmerica's may at last emerge. If so, a sighof relief will be heard in the larger part of theworld-particularly in the corridors ofThomson and Philips,both members of theUS associasion of HDTV manufacturers.

Nevertheless, Europe will lose out onsome aspects, because, although both theUS and Europe have chosen MPEG com-pression, the US has opted for vestigial side -band (VSB). The European 'standard' for dig-ital TV is quadrature amplitude modulation.However, this should not matter much sincethe European mass market for HDTV equip-ment is not likely to come about until the earlypart of the next century.

Apple at the topDataquest, the influential US analyst firm,has announced that Apple Computer Inc. wasthe largest PC maker in the USA in 1993, justahead of rivals IBM and Compaq. Applegained 14.1% of the market, IBM 13.9% andCompaq 10%.

Eighth North WalesRadio & Electronics Show

The Eighth North Wales R&E Show will beheld on 5 and 6 November 1994 at the Aber-conwy Conference Centre & The New Theatre,Llandudno. The Show opens at 10.00 a.m.both days. Entrance fee £ 1.50; under theage of 14 admission is FREE.North Wales Radio Rally Club, Anncott,Hylas Lane, Rhuddlan, Clwyd LL18 5AG.Telephone/fax (0745) 591 704.

Emulation support forembedded 80386CX/EX

German in -circuit emulator manufacturerHitex (see advert on p. 36) have announcedthe first full in -circuit emulators for the newIntel 80386CX/EX embedded micropro-cessors. Using the existing PC -basedT32/386SX emulator as a base, the CX ver-sion allows true in -circuit emulation of theCPU up to 20 MHz (25 MHz to special order)in both 100PQFP and MQFP packages.

A comprehensive information pack isavailable from Hitex covering all 80386 fam-ily development tools.Hitex (UK) Ltd, Sir William Lyons Road,Science Park, Coventry CV4 7EZ,England. Telephone (0203) 692 066.

SpiceAge 3 for WindowsV3 of SpiceAge for Windows gives an orderof magnitude of speed rise for logic simula-tion over SpiceAge 2, previously believed tobe the fastest analogue simulator of its typeavailable. V3 benchmarks at 9 s on the dig-ital test compared with 120 s on V2. Speedgains are also apparent onm some analoguecircuits.

To support this, a new 32 -channel logicanalyser display is available, more digital mod-els are provided and input signal bus struc-tures are supported. The Zetex SPICE li-brary of analogue semiconductor models isshipped with V3 and the analogue side isfurther expanded by a brand new oppera-tional amplifier especially developed to ex-ploit the linear extrapolation pragmas pro-vided in SpiceAge's polynomial functions.Not only is this topology more accurate thanmany SPICE models but is faster to analyse.Those Engineers Ltd, 31 Birkbeck Road,London NW7 4BP, England. Telephone081 906 0155. (See also advert on p. 59).

New autorouter from ULTImateULTImate's new Ripup & Retry Autorouter,the ULTlroute GXR, a Windows -based prod-uct, is a sophisticated autorouter offeringvery high completion rates whilst remaininguser interactive and friendly. ULTlrouteGXR gives the user control over cost factorsand strategies, allowing him to influence thebehaviour of the router and therefore customisethe router to his type of designs.

There are also new versions (4.50) ofULTIboard and (1.50) ULTIcap. Both arenow 32 bit using a Windows corn pliant DOSextender.

ULTIboard, the first PCB design packageto benefit from Real Time Design rule check-ing has been enhanced with powerful TraceShove and Polygon features.

ULTIcap offers several powewrful auto-matic features that reduce editing time, in elud-ing Autowire, Auto Snap to Pin, Auto Junctionand Real Time Electrical Rule Checking.ULTImate Technology (UK) Ltd, 2 BacchusHouse, Calleva Park, AldermastonRG7 4QW, England. Telephone (0734)812 030. (See inside front cover).

New from MaplinA combined clock and thermometer, withan outdoor temperature probe, that can dis-play either °C or °F. The LCD alternates be-tween time and temperature readings at threesecond intervals. The unit, type -coded BU77J,measures 68x52x16 mm, and is priced at£ 9.95 (incl. VAT).

A range of high power speakers, speciallydesigned for use in cars. Power rating from50 W to 200 W. Prices range from £ 34.95 to£ 149.95 each (incl. VAT).

The Fox Wireless Home Alarm has beenspecially designed to help protect the homeor office without spoiling the decorationwith yards of ugly wiring. Because there isno wiring between the intrusion detectorsand the control panel, the system can be eas-ily installed by anyone with average DIYskills. Price £ 99.99 (incl. VAT).

The Auto -inflating digital blood pres-sure monitor is an easy to use, digital, bloodpressure tester designed to remove the com-plexities of measuring blood pressure and pulserate, particularly for those who are not familiarwith the technique. Price £ 74.95 (incl. VAT).Maplin Electronics, P.O. Box 3, RayleighSS6 8LR, England. Phone (0702)552 911.

Z -Match for WindowsThe paper Smith Chart, invented over 50years ago provides a graphical method for solv-ing impedance matching and transmission lineproblems. Number One Systems' new Z -Matchfor Windows program greatly enhances theusefulness and accuracy of Smith Chart tech-niques, and adds a wide range of valuable RadioFrequency Engineering utilities.

An immediately apparent advantage ofZ -Match for Windows is that it works di-rectly with actual lengths of transmissionline and actual resistance and reactance values,eliminating the need for normalisation.

Z -Match for Windows displays impedancevalues produced by Analyser III, Number OneSystems' simulation tool for analogue cir-cuits. In combination, these packages coverthe vast majority of design and analysis prob-lems likely to be faced by engineers and stu-dents working at RF.Number One Systems, Harding Way,St. Ives, Huntingdon, England. Telephone(0480) 461 778. (See also p. 4)


69

LETTERSDear Editor-I have found that the BFX36used in the '100 W high -end power ampli-fier' (March 1994) is no longer available. Infact, I was told that production of this devicewas discontinued in 1991. This does notseem in line with your recently stated pol-icy of trying to only publish designs forwhich the components are actually avail-able. Would the designer please give adviceon component values for the amplifier inputstage using more readily available transis-tors, such as the ZTX851, ZTX951. I ap-preciate that the amplifier performance maynot be quite as good with discrete transistors,but it would at least allow the design to bebuilt. I have built a number of your projectsin the past which I have always found to bevery good and I find it annoying that I can-not build this amplifier to go with them.Simon Platt, Bedford

We are aware of the problems regardingavailability of the BFX36. Although the de-vice is obsolescent, stocks are still availablehere and there, more particularly from oneof our advertisers, C -I Electronics, P.O. Box22089,6360 AB Nuth, the Netherlands. Fax+31 45 241 877. In fact, the BFX36 and itscomplement, the 2N2914, are listed in C -I'sadvert on p. 33 of our March 1994 issue.

Our Central Design Department are ex-amining the specifications of several possi-ble replacements for the BFX36/2N29 14.When suitable types have been found, therelevant update information will be pub-lished in this magazine.

Dear Editor-I have just completed the con-struction of the 'Digital dial' described inthe January 1994 issue. May I relate some quiteinteresting matters that arose during con-struction and testing?

My mistake (discovered after two days)was to use a 74HC4060 instead of the spec-ified 4060. I only did this because I hap-pened to have the 74 version and not a 4060.It does not work! I don 't know why. They aresupposed to be compatible. After the change,

COMPONENT RATINGS

In resistor and capacitor values, decimal pointsand large numbers of zeros are avoided wher-ever possible. Small and large values are usu-ally abbreviated as follows:

p (pico-) =10-12n (nano-) = 10-9µ (micro-) =10-6m (milli-) = 10-3k (kilo-) = 103M (mega-) = 106G (gigs-) =109

Note that nano -farad (nF) is the internationalway of writing 1000 pF or 0.001 µF.Resistors are1/3 watt, 5% metal film types un-

the 'dial' worked really well.I have fitted it to my AR88LF. The dis-

play is flitted behind the 'window' on the frontpanel which should contain an `S' meter.The rest is in a box resting on the IF trans-formers. I tried to use the 6.3 V heater supply,as that is available at the dial light, but Icould not get a suitable transformer. In theend, I put a mains transformer in the boxwith the rest of the components.

If any of your readers have in mind mak-ing a 'Digital Dial' for their AR88, I can letthem have details of an easy way of obtain-ing the LO feed without any soldering or up-ending the receiver (which must weigh agood 25 kg).

One feature of the 'dial' I should mentionis that the three horizontal bars of the firstdigit in the display do not attain full bril-liance. Perhaps this is due to all being fed fromthe same pin of the 4543? No great disad-vantage, but can this be overcome?

On a completely different tack, I wasasked the other thy what S CART stood for.I do not know - do you? Is it an acronym orwhat is it (apart from a standard socket forcomputers)?C.E.H. Benson, Warrington.

Thanks for your letter, which we feel sure willbe of interest to many other readers.

The matter of the brilliance of the first threehorizontal bars has been referred to the de-signer. As soon as his answer is to hand, wewill write to you.

SCART is an acronym of Syndicat desConstructeurs d'Appareils Radiorecepteurset Televiseurs, the French association ofradio and television manufacturers. This as-sociation decided in the early 1980s to ter-minate various inputs to, and outputs from,TV receivers into a 21 -way socket, whichhas since become a European standard.

Dear Editor-I read with interest your articleon the SCMS inhibitor for DAT machines(Copybit Eliminator - February 1994). Iwould like to make this unit for use betweentwo Sony Portable DATs, i.e., the D3 and D7machines. A separate box would be requiredwith either coax or fibre optic connectors.

less otherwise specified.

The direct working voltage of capacitors (otherthan electrolytic or tantalum types) is assumedto be 60 V. As a rule of thumb, a safe valueis about 2x direct supply voltage.

Direct test voltages are measured with a 201S2/Vmeter unless otherwise specified.

Mains (power line) voltages are not listed in thearticles. It is assumed thatourreaders know whatvoltage is standard in their part of the world.

Readers in countries that use 60 Hz supplies,should note that OUT circuits are usually designedfor 50 Hz. This will not normally cause prob-lems, although if the mains frequency is usedfor synchronization, some modification may

I am a musician, not a technical person,but I can use a soldering iron, so any help youcan give me would be gratefully appreci-ated. I presume any components requiredcan be purchased from Maplin or any othersuch supplier.G. Drucquer, Frimley Green.

We are currently working on a stand-aloneversion, i.e, one that can be inserted betweentwo DAT recorders as you require. We planto publish the relevant article in our July/August1994 issue. Briefly, the design will consist ofthe 'Digital audio enhancer' (February1993) in slightly modified form, the `Copybiteliminator', and a small add-on board. Allthis is, however, tentative and will depend onthe tests our design department are currentlycarrying out proving successful.

Dear Editor-I have sent for the PIC pro-grammer project that appeared in the March1994 issue of your magazine and in the articleeight 499 1% resistors are needed. I havelooked in various catalogues and TV andelectronics magazines and I cannot find a sourcefor such components. Please could you tellme where I could find them.

Why didn't you use presets or if thesewere not accurate enough, why didn't you usemulti turn presets.

Have you have ever considered having fullkits (incl. all components) for your projects.M. McCabe, Redcar

Precision 1%, and even 0.1%, resistors areavailable from specialist audio/hi-fi com-ponent retailers. You may, for instance, tryViewcom-see pages 8 & 9 of our Marchand April 1994 issues. Complete kits areavailable from C -I Electronics-see the ad-vert on p.33 of our April 1994 issue.

Presets cannot be expected to give any-where near the same performance as preci-sion resistors, but we have, nevertheless,passed your query to the designer.

As international book/magazine pub-lishers, we cannot go into the specialist elec-tronics trade, but leave this to the experts:our advertisers and other electronic componentretailers.

be required.

The international letter symbol' U' is used forvoltage instead of the ambiguous 'V' . The let-ter V is reserved for 'volts' .

The size of a metric bolt or screw is definedby the letter M followed by a number corre-sponding to the overall diameter of the threadin mm, the x sign and the length of the bolt orscrew, also in mm. For instance, an M4x6 bolthas a thread diameter of 4 mm and a length of6 nun. The overall diameter of the thread inthe B A sizes is: 0 BA = 6.12 mm; 2 BA =4.78 mm; 4 BA = 3.68 mm; 6 BA = 2.85 mm;8 BA= 2.25 mm.


70

READERS SERVICESExcept in the USA and Canada, all orders, except forsubscriptions and past issues (for which see below),must be sent BY POST to our Dorchester office usingthe appropriate form opposite. Please note that wecan not deal with PERSONAL CALLERS, as no stockis carried at the editorial and administrative office.Readers in the USA and Canada should send orders,except for subscriptions (for which see below), to OldColony Sound Lab, Peterborough, whose full addressis given on the order form opposite. Please includeshipping cost according to total order value. For sur-face delivery in the USA, if order is less than $50, in-clude $3; $50+, $4. For Canada surface, if less thanUS$50, include US$5; US$50+, US$7.50. For air orother deliveries, please inquire. Please allow 4-6weeks for delivery.All other customers must add postage and packingcharges for orders up to £25.00 as follows: UK andEire £1.95; surface mail outside UK £2.45; Europe(airmail) £2.95; outside Europe (airmail) £3.70. For or-ders over £25.00, but not exceeding £100.00, thesep&p charges should be doubled. For orders over£100.00 in value, p&p charges will be advised.

SUBSCRIPTIONS & PAST ISSUES

Subscriptions and past issues, if available, should beordered from Worldwide Subscription Service Ltd, Unit4, Gibbs Reed Farm, Pashley Road, TICEHURST TN57HE, England. For subscriptions, use the order formon the opposite page. Prices of past issues (exceptJuly/August and December), including postage for sin-gle copies, are £2.70 (UK and Eire); £3.00 (surfacemail outside UK); £3.20 (air mail Europe); £3.95 (air-mail outside Europe). Prices of past July/August andDecember issues, including postage for single copies,are £3.75 (UK); £4.00 (surface mail outside UK); £4.25(airmail Europe); and £5.00 (airmail outside Europe).

PAST ARTICLES

Photocopies of articles from January 1978 onwardscan be provided, postage paid, at £1.95 (UK and Eire),£2.10 (surface mail outside UK), £2.45 (airmailEurope), or £2.70 (airmail outside Europe). In case anarticle is split into instalments, these prices are applic-able per instalment. Photocopies may be ordered fromour editorial and administrative offices.

COMPONENTS

Components for projects appearing in Elektor Elec-tronics are usually available from appropriate advertis-ers in this magazine. If difficulties in the supply ofcomponents are envisaged, a source will normally beadvised in the article. It should be noted that thesource(s) given is (are) not exclusive - other suppli-ers may also be able to help.

BOOKS

For book availability, see advertisement on page 67.

SHELF BOX

Elektor Electronics shelf box £2.95 $6.00

FRONT PANEL FOILS

PROJECT No. Price Price(E) (US$)

Timecode interface 910055-F 8.80 17.60Digital functiongenerator 910077-F 10.60 21.20

4 -Megabyte printerbuffer 910110-F 11.45 22.90FM tuner 920005-F 13.20 26.404MB printer buffer card 920009-F 8.25 16.50LC meter 920012-F 11.45 22.90Guitar tuner 920033-F 8.80 17.60NICAM decoder 920035-F 8.25 16.5012VDC to 240VACinverter 920038-F 16.15 32.30

Audio DAC 920063-F 10.00 20.00Dig. audio/visual system 920022-F1 10.00 20.00

920022-F2 19.40 38.80920022-F3 28.80 57.60

1.2 GHz multifunctionfrequency meter 920095-F 13.80 27.60U2400B NiCd batterycharger 920098-F 8.75 17.50Workbench PSU 930033-F 17.00 34.00

PROJECT

Inexpensive phase meterMini preamplifierAF rms voltmeter

No.

930046-F930106-F930108-F

Price Price(C) (US$)

17.25 34.50Not available17.25 34.50

EPROMS / PALS / MICROCONTROLLERS

Amiga mouse/joystickswitch (1 x GAL 16V8) 6001 8.25 16.504 -Megabyte printer buffer(1 x 2764) 6041 15.30 30.608751 emulatorincl. system disk (MSDOS) 6051 29.40 58.80Connect 4 (1 x 27C64) 6081 15.30 30.60EMON51 (8051 assemblercourse) (1 x 27256+disk 1661) 6061 20.00 40.00EMON51 (8051 assemblercourse) (1 x 27256+disk 1681) 6091 20.00 40.00FM tuner (1 x 27C256) 6101 15.30 30.60Multi -purpose Z80 card:GAL set (2 x GAL 16V8) 6111 11.15 22.30Multi -purpose Z80 card:BIOS (1 x EPROM 27128) 6121 15.30 30.601.2 GHz multifunctionfrequency meter(1 x 27C256) 6141 11.45 22.90Digital audio/visual system(1 x 27C256) 6171 10.30 20.60TV test pattern generator(1 x 27256) 6151 13.00 26.00DiAV system. Package:1 x 27512; 2 x GAL; 1 xfloppy disk (MSDOS) 6181 30.50 61.00PAL test pattern generator(1 x GAL 20V8-25) 6211 9.40 18.60800535 assembler course(1 x EMON52 EPROM and1 x disk 1811) 6221 17.05 34.10Watt-hour meter (1 x 27256) 6241 10.00 20.00Four fold DAC (1 x GAL) 6251 10.75 21.50Multipurpose display decoder(1 x 2764) 6261 11.50 23.00Telephone -controlled switch(1 x 2764) 6271 14.50 29.00Relative humidity meter(1 x 2764) 6301 14.50 29.00535 card w. EPROM emulator(1 x PAL; 1 x GAL) 6311 26.00 52.00Copybit eliminator (1 x GAL16V8 and 1 x MACH110) 6321 42.25 84.50RDS decoder (1 x 27C64) 6331 14.50 29.00I2C tester (1 x GAL 6001) 6341 30.75 61.50Mains signalling system(1 x 27C64) 6371 13.25 26.508751 programmer (1 x 8751) 7061 46.40 92.80Microcontroller NiCd charger(1 x ST62E15) 7071 10.00 20.00Maxi micro clock (clock) 7081 11.50 23.00Maxi micro clock (darkroom timer) 7091 11.50 23.00Maxi micro Clock (cooking timer) 7101 11.50 23.00Mini micro clock (ciock) 7111 11.50 23.00Mini micro clock (darkroom timer) 7121 11.50 23.00Mini micro Clock (cooking timer) 7131 11.50 23.00VHF/UHF TV tuner(1 x 87C51) 7141 25.75 51.50Microntroller-driven UART(1 x ST62T10) 7151 17.25 34.50PIC programmer(1 x PIC17C42 and 1 x disk) 7161 50.00 100.00

DISKETTES

Plotter driver (D. Sijtsma) 1541 11.15 22.30I/O interface for Atari 1571 7.65 15.30Tek/Intel file converter 1581 7.65 15.30B/W video digitizer 1591 11.15 22.30Timecode interface 1611 7.65 15.30RTC for Atari ST 1621 7.65 15.3024 -bit colour extensionfor video digitizer 1631 11.15 22.30PC controlled weatherstation - 3 (supersedesdisks 1551 and 1561) 1641 7.65 15.308051/8032 Assembler course(IBM version) 1661 7.65 15.308051/8032 Assemblercourse (Atari version) (3.5") 1681 7.65 15.30AD232 converter 1691 7.65 15.30GAL programmer (3 disks;

PROJECT No. Price Price(C) (US$)

upgrade: June 1993) 1701 11.15 22.30Multi -purpose Z80 card 1711 7.65 15.30Fuzzy Control One 1721 7.75 15.50Pascal library for MMC 1751 9.70 19.40Speech/sound memory 1771 7.65 15.30PC -aided transistor tester 1781 7.50 15.00IR receiver and DTMF decoderfor 80C32 SBC 1791 9.00 18.00800535 assembler course 1811 8.80 17.60I2C opto/relay card 1821 7.65 15.30Video digitizer for PCs 1831 14.50 29.00GAL programmer for Amiga 1841 11.00 22.00I2C alphanumerical display 1851 8.50 17.00Philips preamplifier 1861 8.50 17.00GAL programmer (excl. OpalJr. disks) 1881 10.75 21.50Precision clock for PCs 1871 8.50 17.00X2404 -to -8751 interfacing 1891 8.50 17.00Mains signalling system 1911 9.75 19.50SIM - an 8051 simulator 1931 34.25 68.50

PRINTED CIRCUIT BOARDS

Printed circuit boards whose number is followed by a+ sign are only available in combination with the as-sociated software item, and can not be supplied sepa-rately. The indicated price includes the software.

JANUARY 1994Digital dialRDS decoderincl. EPROM (6331)

I2C testerincl. GAL (6341)

Telephone -controlled switchincl. EPROM (6271)

FEBRUARY 1994800535 single -boardcomputerCopybit eliminatorincl. MACH and GAL

920161

930121+

930128+

934054+

924046

930098+

12.75

23.75

36.25

37.25

14.10

46.25

25.50

51.50

72.50

74.50

28.20

92.50Mini preamplifierBidirectional RS232 -to -

930106 29.25 58.50

Centronics converter 930134 14.00 28.0024 cm FM ATV transmitter PCB available from author

MARCH 1994PIC programmerincl. software set 7161100W AF amplifier- adaptor board 930039- amplifier board 920135-1- protection board 920135-2Mini I/O card for CasioFX850/880P 930090AF signal tracer 940006Electronic fuse 936071

APRIL 1994Mains signalling system - 1

(receiver) 940021-168HC11 processor board 930123RS232 speedometer 930119Stroboscope lightHeadphones amplifierHalogen light dimmerRS232 interface foruniversal bus

940022940016940034

940048+ 64.75 129.50

8.25 16.5019.40 38.807.95 15.90

Not availableNot availableNot available

10.25 20.507.75 15.50

Not availableNot available18.75 37.50Not available

924048 Not available

MAY 1994Diffferential probe foroscilloscopes 940018 7.75 15.50Mains signalling system - 2(transmitter) (incl. disk1911 and EPROM 6371) 940021-2+ 33.25 66.50Morse decoder contact Velleman distributorGeneral-pupose sensormonitor 916107 Not availableTV sound to light unit 936038 Not available

A list of all PCBs, software products and front panels available through the Readers Services ispublished in the March, June, September and December issues of Elektor Electronics


xr

Please send this order form to *Elektor Electronics (Publishing)P.O. Box 1414Dorchester DT2 8YHENGLANDTel. (0305) 250995Fax (0305) 250996

*USA and Canada residents only use $ prices, and sendorder form to:Old Colony Sound Lab, P.O. Box 243, Peterborough,NH 03458.Tel. (603) 924-6371, 924-6526, Fax: (603) 924-9467

ORDER FORM 5-94

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TERMS OF BUSINESSHOW TO PAYUnless you have an approved credit accountwith us, all orders must be accompanied bythe full payment, including postage and pack-ing charges as stated on page 70, section I.

Payment may be made by cheque drawnon a London clearing bank (but see para. 4below), postal order, VISA, ACCESS, MAS-TERCARD or EUROCARD (when paying bycredit card, the order must go to the card-holder's address). Do not send cash throughthe mail. Cheques and postal orders should becrossed and made payable to Elektor Electronics(Publishing)'.

Payment may also be made by direct trans-fer from a private or business Giro account toour Giro Account No. 34 152 3801 by com-pleting and sending to the National Giro Centre,in a National Giro postage paid envelope, aNational Giro transfer/deposit form. Do not sendGiro transfers direct to us, as this will delay yourorder.

If you live outside the UK, payment mayalso be made by Bankers' sterling draft drawnon a London clearing bank, Eurocheque madeout in pounds sterling (with holder's guaran-tee card number written on the back), or US orCanadian dollar cheque, but such cheques, ac-cepted at the exchange rate prevailing at the timeyour order is received, must he increased bythe equivalent of £15.00 to cover our bankers'negotiating fee.

If you pay by Bankers' sterling draft, makeclear to the issuing bank that your full nameand address MUST be communicated to theLondon clearing bank.

Our bankers are National WestminsterBank PLC, 100 High Street, BRENTFORD

r

TW8 8AY, England. Our account number is4285 0134.

DELIVERYAlthough every effort will be made to dispatchyour order within 2-3 weeks from receipt of yourinstructions, we can not guarantee this time scalefor all orders.

RETURNSFaulty goods or goods sent in error may be re-turned for replacement or correction, but notbefore obtaining our consent. All goods re-turned should be packed securely in a paddedbag or box, enclosing a covering letter statingthe dispatch note number. If the goods are re-turned because of a mistake on our part, wewill refund the return postage. Goods returnedfor refund must be in resaleable condition andwill be subject to a 10% handling charge witha minimum charge of £2.50.

DAMAGED GOODSClaims for damaged goods must be received atour Dorchester office within 10 days (UK); 14days (Europe) or 21 days (all other countries)from the date on our "Recorded Delivery" slip.

CANCELLED ORDERSAll cancelled orders will be subject to a 10%handling charge with a minimum charge of£2.50.

PATENTSPatent protection may exist in respect of circuits,devices, components, and so on, described inour books or magazines. Elektor Electronics(Publishing) do not accept responsibility or li-

ability for failing to identify such patent orother protection.

COPYRIGHTAll drawings, photographs, articles, printed -cir-cuit boards, EPROM5, and cassettes published inour books or magazines (other than in third -partyadvertisements) are copyright and may not bereproduced or transmitted in any form or byany means, including photocopying and record-ing, in whole or in part, without the prior per-mission of Elektor Electronics (Publishing) inwriting. Such written permission must also beobtained before any part of these publicationsis stored in a retrieval system of any nature.

Nothwithstanding the above, printed -circuitboards may be produced for private and personaluse without prior permission.

LIMITATION OF LIABILITYElektor Electronics (Publishing) shall not beliable in contract, tort, or otherwise, for anyloss or damage suffered by the purchaser what-soever or howsoever arising out of, or in con-nexion with, the supply of goods or services byElektor Electronics (Publishing) other than tosupply goods as described or, at the option ofElektor Electronics (Publishing), to refund thepurchaser any money paid in respect of thegoods.

LAWAny question relating to the supply of goodsand services by Elektor Electronics (Publishing)shall be determined in all respects by the lawsof England.

May 1994

Annual subscription rates (1994)

United Kingdom £27.00Rest of the world (surface mail) £33.00AIRMAILEurope & Eire £34.00USA & Canada $57.00Middle East & North Africa £43.00Central & southern Africa £43.00Central & South America £43-00Australia & New Zealand £45.00Far East & South Pacific regions £45.00

Payment may be made by cheque in sterling drawnon a London clearing bank (but see below), postalorder, VISA, ACCESS, MASTERCARD or EUROCARD (in whichcase the subscription must be sent to the cardholder's ad-dress) or by direct transfer to our Giro Account no. 34152 3801. Do not send cash through the mail. Chequesand postal orders should be made payable to `ElektorElectronics Publishing'. Giro transfers should be made bycompleting and sending the appropriate transfer/depositform to the National Giro Centre (UK) or to your nationalGiro Centre.

If you live outside the United Kingdom, payment mayalso be made by Bankers' sterling draft drawn on a Londonclearing bank or Eurocheque. Eurocheques should bemade out in pounds sterling and have the holder's guar-antee card number written on the back.

only may pay in $US cheques.

The standard subscription order period is twelve months.If a permanent change of address during your subscrip-tion period means that copies have to be dispatched by amore expensive service, no extra charge will be made.Similarly, no refund will be made, nor expiry date extended,if a change of address allows the use of a cheaper service.

Student applications, which qualify for a 10% (ten percent) reduction in current rates, must be supported by ev-idence of studentship signed by the head of the college,school or university faculty.

Please note that new subscriptions take about four weeksfrom receipt of order to become effective.

Cancelled subscriptions will be subject to a charge of25% (twenty-five per cent) of the full subscription price or£7.50, whichever is the higher, plus the cost of any issuesalready dispatched. Subscriptions cannot be cancelled afterthey have run for six months or more.

Our bankers are National Westminster Bank PLC, SortingCode 60-03-23, 100 High Street, Brentford TW8 8AY,England. Our account number is 4285 0134.

May 1994

L

US dollar cheques. Subscribers in the USA and Canada



Surplus alwayswanted for cash! THE ORIGINAL SURPLUS WONDERLAND. Surplus always

wanted for cash',

LOW COST PC SPECIALISTS - ALL EXPANDABLE - ALL PC COMPATIBLE8088 XT - PC99

ref 256k RAM - expandable

to 640k 4.7 Mhz speed 360k 5-1/4" floppy 2 serial & 1 parallel ports MS-DOS 4.01

Factory burnt -in Standard 84 key

keyboard iln2c"ireedn screen

In good used condition

Optional FITTED extras: 640K RAM £39. 12" CGA colourmonitor with card £39. 2nd 5-1/4" 360K floppy £29.95. 20mbyte MFM hard drive £99.

only£99.00,F,FLOPPY DISK DRIVES

51/4 " from £22.95 - 31/2" from £21.95!Massive purchases of standard 51/4" and 31/2" drives enables usto present prime product at industry beating low prices! All units(unless stated) are removed from often brand new equipmentand are fully tested, aligned and shipped to you with a 90 dayguarantee and operate from standard voltages and are of stand-ard size. All are IBM-PC compatible (if 31/2" supported).3.5" Panasonic JU363/4 720K or equivalent £29.95)B)3.5" Mitsubishi MF355C-L. 1.4 Meg. Laptops only` £29.95)B(3.5" Mitsubishi MF355C-D. 1.4 Meg. Non laptop £29.95(B)5.25" EXTRA SPECIAL BRAND NEW Mitsubishi MF501B

360K. Absolutely standard fits most computers £22.95(B)Data cable included in price.

Shugart 800/801 SS refurbished & tested £175.00(E)Shugart 851 double sided refurbished & tested £275.00)E)Mitsubishi M2894-63 double sided switchable

hard or soft sectors- BRAND NEW £250.00)E)Dual 8" drives with 2 mbyte capacity housed in a smart casewith built in power supply! Ideal as exterior drives! £499.00(F)End of line purchase scoop! Brand new NEC D2246 8" 85megabyte of hard disk storage! Full CPU control and industrystandard SMD interface. Ultra hi speed transfer and access timeleaves the good old ST506 interface standing. In mint conditionand comes complete with manual. Onl £299(E)

THE AMAZING TELEBOX!Converts your colour monitor into a

QUALITY COLOUR TV!!

I

286 AT - PC286

"440 640k RAM expandable 2 serial & 1 parallelwith standard SIMMS ports

12 Mhz Landmark speed MS-DOS 4.01 20 meg hard disk Co -processor socket 1.2 meg 5-1/4" floppy Enhanced 102 key 1.4 meg 3-1/2" floppy keyboard

Clock & calendar with EGA driver on board batteryback up

BRAND NEW AND BOXED!

oniyE249.00,,PThe Philips 9CM073 is suggested for the PC286 and the\

CM8873 for the PC386. Either may use the SVGA MTS-9600if a suitable card is installed. We can fit this at a cost of £49.00

`or the PC286 and £39.00 for the PC386.

POWER SUPPLIESPower One SPL200-5200P 200 watt (250 w peak).Semi openframe giving +5v 35a, -5v 1.5a, +12v 4a (8a peak), -12v 1.5a,+24v 4a (6a peak). All outputs fully regulated with over voltageprotection on the +5v output. AC input selectable for 110/240vac. Dims13" x 5" x 2,5". Fully guaranteed RFE. £85.00 (B)

Power One SPL130. 130 watts. Selectable for 12v (4A) or 24 v(2A). 5v /0 20A. ± 12v @ 1.5A. Switch mode. New. £59.95)B)Astec AC -8151 40 watts. Switch mode. +5v 18 2.5a. +12v2a. -12v 18 0.1a. 6-1/4" x4" x 1-3/4".New £22.95(B)Greendale 19ABOE 60 watts switch mode.+5v 6a,±12v1a,+15v 18 1 a. RFE and fully tested.11 x 20 x5.5cms. £24.95(C)Conver AC130. 130 watt hi -grade VDE spec.Switch mode.+5v

386 AT - PC38641113

2 meg RAM expandedby slots

20 Mhz with 32k cache.Expandable to 64k

40 meg hard disk 1.2 meg 5-1/4" floppy VGA card installed

BRAND NEW

a.

31.161rags:,7

2 serial & 1 parallelports

MS-DOS 4.01 Co -processor socket Enhanced 102 keyboard Kwik Disk Accelerator

Software - FREEAND BOXED!

oniYE425.00 (9

14" Forefront Model MTS-9600 SVGAmultisync with resolution of 1024 x 768 0 28pitch "Text" switch for word processing etcOverscan switch included Ideal for the PC-

s 386 or PC -286 with SVGA card added Alsocompatibe with BBC, Amiga, Atari (includingthe monochrome high resolution mode), Ar-

chimedes etc. In good used condition (possible minor screen

14" Philips Model CM8873 VGA multisyncburns). 90 day guarantee. 15" x 14' x 12". Only £159)E)

with 640 x 480 resolution. CGA, EGA orVGA, digital/analog, switch selectable.Sound with volume control. There is also aspecial "Text" switch for word processing,spreadsheets and the like. Compatible withIBM PC's, Amiga, Atari (excluding themonochrome high resolution mode), BBC,

15a, -5v 18 1a,±12v 186a.27 x 12.5 x 6.5cms.New. £49.95)C) Archimedes etc. Good used condition (possible minor screenBosher113090.Switch mode.Ideal for drives & system. +5v@ 6a, burns) 90 day guarantee. 15' x 14" x 12". Only

(E+12v 18 2.5a, -12v 18 0.5a, -5v 18 0.5a. £29.95)B) Philips 9CM073 similar (not identical) to above for EGA/CGA)Farnell G6/40A. Switch mode. 5v 18 40a.Encased £95.00)C)Parnell G24/5S. As above but 24v @

PC and compels. 640 x 350 resolution. With Text switch with5a. £65.00(C) amber or green screen selection. 14" x 12" x 13-1/2"... ..... £99(E)

KME 10" high definition colour monitors. Nicetight 0.28" dot pitch for superb clarity andmodern styling. Operates from any 15.625 khzsync RGB video source, with RGB analog andcomposite sync such as Atari, CommodoreAmiga, Acorn Archimedes & BBC. Measuresonly 13.5" x 12" x 11". Also works as quality Tv witn our HITS

BBC Model B type computer on a board. A major purchase Telebox. Good used condition. 90 day guarantee. Only £125 (E)

BBC Model B APM Board£100 CASH FOR THE

MOST NOVELDEMONSTRATABLE

APPLICATION!

allows us to offer you the PROFESSIONAL version of the BBCcomputer at a parts only price. Used as a front end graphicssystem on large networked systems the architecture of the BBCboard has so many similarities to the regular BBC model B thatwe are sure that with a bit of experimentation and ingenuity many

. I useful applications will be found for this board!! It is suppliedcomplete with a connector panel which brings all the I/O to 'D'

The TELEBOX consists of an attractive fully cased mains and BNC type connectors - all you have to do is provide +5 andpowered unit, containing all electronics ready to plug into a host ± 12 v DC. The APM consists of a single PCB with most majorof video monitors made by manufacturers such as ic's socketed. The ic's are too numerous to list but include aMICROVITEC, ATARI, SANYO, SONY, COMMODORE, 6502, RAM and an SAA5050 teletext chip. Three 27128PHILIPS, TATUNG, AMSTRAD and many more. The composite EPROMS contain the custom operating system on which wevideo output will also plug directly into most video recorders, have no data, On application of DC power the system boots andallowing reception of TV channels not normally receivable on provides diagnostic information on the video output. On boardmost television receivers (TELEBOX MB). Push button controls DIP switches and jumpers select the ECONET address andon the front panel allow reception of 8 fully tuneable 'off air' UHF enable the four extra EPROM sockets for user software. Appx.colour television or video channels. TELEBOX MB covers vir- dims: main board 13" x 10". I/O board 14" x 3". Supplied testedtually all television frequencies VHF and UHF including the with circuit diagram, data and competition entry form.HYPERBAND as used by most cable TV operators. Composite Only £29.95 or 2 for £53 (B)and RGB video outputs are located on the rear panel for directconnection to most makes of monitor. For complete compatibility- even for monitors without sound - an integral 4 watt audioamplifier and low level Hi Fi audio output are provided asstandard.Telebox ST for composite video input monitors £32.95Telebox STL as ST but with integral speaker £36.50Telebox MB as ST with Multiband tuner VHF -UHF -Cable.

& hyperband For overseas PAL versions state5.5 or 6mhz sound specification. £69.95

Telebox RGB for analogue RGB monitors (15khz) £69.95Shipping code on all Teleboxes is (B)

RGB Telebox also suitable for IBM multisync monitors with RGBanalog and composite sync. Overseas versions VHF & UHF call.

SECAM / NTSC not available.

- , - a a -

Brand new and boxed 230 volts uninterruptable power suppliesfrom Densei. Model MUK 0565-AUAF is 0.5 kva and MUD1085-AHBH is 1 kva. Both have sealed lead acid batteries. MUKare internal, MUD has them in a matching case. Times frominterrupt are 5 and 15 minutes respectively. Complete with fulloperation manuals MUK ..£249 (F) MUD £525 (G)

1992 Winter IssueSOO. .000.

.050

SPECIAL INTEREST

KME as above for PC EGA standard £145 (E)Brand new Centronic 14" monitor for IBM PC and compatiblesat a lower than ever price! Completely CGA equivalent. Hi-resMitsubishi 0.42 dot pitch giving 669 x 507 pixels. Big 28 Mhzbandwidth. A super monitor in attractive style moulded case.Full90 day guarantee. Only £129 (E)NEC CGA 12" IBM-PC compatible. Highquality ex -equipment fully tested with a 90day guarantee. In an attractive two toneribbed grey plastic case measuring 15"L x13"W x 12"H. The front cosmetic bezel hasbeen removed for contractual£69

(E)reasons. Only20", 22" and 26" AV SPECIALS

Superbly made UK manufacture. PIL all solid state colourmonitors, complete with composite video & sound inputs. Attrac-tive teak style case. Perfect for Schools,Shops,Disco, Clubs.In EXCELLENT little used condition with full 90 day guarantee.

20"....£135 22"....£155 26"....£185 (F)CALL FOR PRICING ON NTSC VERSIONS!

Superb Quality 6 foot 40u

19" Rack CabinetsMassive Reductions

Virtually New, Ultra Smart!Less Than Half Price!

Top quality 19" rack cabinets made in UKby Optima Enclosures Ltd. Units featuredesigner, smoked acrylic lockable frontdoor, full height lockable half louvered back

HP 7580A Al 8 pen high speed drum plotter £1850door and removable side panels. Fully ad-justable internal fixing struts, ready

Kenwood DA -3501 CD tester, laser pickup simulator £ 350 punched for any configuration of equipment mounting plus ready - - mounted integral 12 way 13 amp socket switched mains distribu-tion strip make these racks some of the most versatile we have

Microline 183. NLQ 17x17 dot matrix. Full width. £139 (D) ever sold. Racks may be stacked side by side and thereforeHyundai HDP-920. NLQ 24x18 dot matrix full width. £149 (D) require only two side panels or stand singly. Overall dimensionsGime LetterPro 20 daisy. Qume OS -3 interface. £39.95 (D) are 77-1/2"H x 32-1/2"D x 22"W. Order as:Centronics 152-2 9 x 7 dot matrix. Full width. £149 (D) Rack 1 Complete with removable side panels £275.00 (G)Centronics 159-4 9 x 7 dot matrix.Serial. 9-1/2" width £ 99 (D) Rack 2 Less side panels £145.00 (G)

of Dispiay News now available - send large SAE - PECKED with bargain:I

.

Trio 0-18 vdc bench PSU. 30 amps. NewFujitsu M3041 600 LPM band printerDEC LS/02 CPU boardRhode & Schwarz SBUF TV test transmitter

25-1000mhz. Complete with SBTF2 Modulator £6500Calcomp 1036 large drum 3 pen plotter £ 650Thurlby LA 160B logic analyser £ 3751.5Icw 115v 60hz power source £ 950Anton Pillar 400 Hz 3 phase frequency converter 75Kw POANewton Derby 400 Hz 70 Kw converter POANikon PL -2 Projection lens meter/scope £750Sekonic SD 150H 18 channel Hybrid recorder £2000

II

6 6 0

I I

0 $

I I I III

£ 470£2950£ 150

veo

o

CS

9 9

I: : : :

I ;i

VisaAll prices for UK Mainland. UK customers add 17.5% VAT to TOTAL order amount. Minimum order £10. PO orders from Government,Universities,Schools & Local Autho 'tieswelcome -minimum account order £30. Carriage charges (A)=£2.00. (A1).£3.75. (B)-£5.50. (C)=E8.50. (D)=£11.50. (E)=£14.00 (F)=E18.00 (G)=Call. Scotland surcharge: call.All goods supplied subject to our standard Conditions of Sale and unless otherwise stated guaranteed for 90 days. All guarantees on a return to base basis.Rights reserved tochange prices & specifications without prior notice. Orders subject to stock. Quotations willingly given for higher quantities than those stated. Bulk surplus always wanted forcash.


74

ELEKTOR ELECTRONICS is available from, among others:

CRICKLEWOODELECTRONICS LIMITED40 Cricklewood Broadway,

London NW2 3ETTelephone 081 450 0995

Fax 081 208 1441

L.P. HANNEYYour electronic componentspecialist for Avon, Wilts &

Somerset.77 Lower Bristol Road, Bath,

Avon, Telephone 0225424811

AAGE NIELSEN1 Sortedam DosseringenDK-2200 Copenhagen,

Denmark,Telephone 01 39 30 10

Fax 031 39 05 02

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Terceira 191107 Lisboa, PortugalTelephone 932 4752

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LjubljanaSlovenia

Telephone 061 150 196

THE ELECTRONIC SHOPElectronic components, test

equipment, telephoneaccessories, computer

accessories, microphones,disco lighting, speakers, turntables, mixers, meters, stylus.

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Telephone 061 834 1185

HELMHOLT ELEKTRONIKFarvevej 2

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Electronic componentspecialists. Amateur radio

equipment.13 St. Benedict Street,

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P 0 Box 332DK-7100 Vejle, DenmarkTelephone 75 83 25 33

INEL Co.P.O. Box 1397

JL. Hariang Banga No. 3Bandung 40116

IndonesiaOMNI ELECTRONICSStock a wide range of

electronic components.174 Dalkeith Road,

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BEBEK ELECTRONICSHirsimetsantie 26

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Advertising Standards AuthorityBadger BoardsB K ElectronicsBull ElectricalCanal Bridge AudioCirkit DistributionCricklewood ElectronicsDisplay ElectronicsElektor ElectronicsESR Electronic ComponentsEurocom International LtdHitex (UK) LtdInstrutek (UK)Intar OyKMN DevelopmentsLabcenterMaplin Electronic SuppliesMicroAmpsNumber One Systems LtdPico Technology LtdPOWERwareRobinson MarshallSigCadSpeaker BuilderStewart of ReadingSuma Designs

INDEX OF ADVERTISERS

36, 514915

6051

27

4573

67, 7431

51

3621

51

4961

Back cover27

42659

Inside back cover49362720

Those EngineersTsien (UK) LtdUltimate TechnologyViewcom Electronics

5955

Inside front cover8, 9

ADVERTISING SPACEfor the June 1994 issue may be reservednot later than Thursday 14 April 1994 by

Elektor Electronics (Publishing)Advertisement Office

3 Crescent TerraceCheltenham GL50 3PE

EnglandTelephone (0242) 510 760

Fax (0242) 226 626

to whom all correspondence, copy instructionsand artwork should be addressed.



Design and Verify Circuits. Fasts

Analog Module includes: complete control over all component values ideal and real -world models for active

components resistors, capacitors, inductors, transformers,relays, diodes, Zener diodes, LEDs, BJTs,opamps, bulbs, fuses, J1-1 1 s, and MOSFETs

manual, time -delay, voltage -controlled andcurrent -controlled switches

independent, voltage -controlled and current -controlled sources

multimeter function generator (1 Hz to 1 GHz) dual -trace oscilloscope (1 Hz to 1 GHz) Bode plotter (1 mHz to 10 GHz) SPICE simulation of transient and steady-state

responseids Edit circuit Window lidid I5 Ct.-1=M ILQI...11

1ritessd3 El, P.1. a

i!!!1111 10.,.. -

11.1 i

0

.--0

4.0

I Ill...,a, .larall161

ll=7-----1-1 Word C... -.ter -I tddic Analyzer

210 ,,....-......... E1133EN i t.ni.

--,SURSYPa" Ef r PI1:.7t:nt t

4) 6 6 6 6 6 6 b WO

6 6 6 6 6 6 4, 6 0

Digital Module includes: fast simulation of ideal components AND, OR, XOR, NOT, NAND and NOR gates RS, JK and D Hip -flops LED probes, half -adders, switches and seven -

segment displays word generator (16 eight -bit words) logic analyzer (eight -channel) logic converter (converts among gates, truth

table and Boolean representations)

Complement Your Test BenchHere's why Electronics Workbench belongs on your test bench:Wires route themselves. Connections are always perfect. And thesimulated components and test instruments work just like the realthing. The instruments are indestructible and the parts bin holdsan unlimited supply of each component. The result: thousands ofelectronics professionals and hobbyists save precious time andmoney. Over 90% would recommend it to their friends andcolleagues. Electronics Workbench: the ideal, affordable tool todesign and verify your analog and digital circuits before youbreadboard.And now the best is even better - Electronics WorkbenchVersion 3.0 is here. It simulates more and bigger circuits, andsets the standard for ease of use. Guaranteed!

Features in Version 3 new components include JFETs, MOSFETs,voltage -controlled and current -controlled sourcesand manual, time -delay, voltage -controlled andcurrent -controlled switches

real -world models for opamps, BJTs, J FE I s,MOSFETs and diodes - over 100 models available

MS-DOS version now supports up to 16 MB ofRAM for simulation of bigger circuits

new Microsoft® Windows ° version available technical support now also available onCompuServe

ElectronicsWorkbench-?, .1 nirt lab m NM.,

Just £199!

Electronics WorkbenchThe electronics lab in a computer -

Call: (0827) 66212ROBINSON MARSHALL (EUROPE) LTD.17 Middle Entry, Tamworth, Staffordshire, England B79 7NJFax: (0827) 58533

*30 -clay money -back guarantee.. -

Shipping charges - UK £4.99. All prices are plus V.A.T.All trademarks are the property of their respective owners. INTERACTIVE

FULL GUIDE TO ELE

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BS 5750Part 2 1987

Level B:Quality Assurance

RS12750

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· your design ideas are quickly captured using the ulticap schematic design tool. ulticap uses...

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