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THE PRACTICAL MAGAZINE WITH THE PROFESSIONAL APPROACHUK £1.60 IR £2.35 (incl. VAT) December 1988
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Pitch control for CD playersAutonomous I/O controllerComposite-to-TTL adaptorTest pattern generatorChip for Artificial IntelligenceBackground to E2PROMsIBC 1988: a reportCUMULATIVE INDEX 1988
11 19 770268 451012
EE
December 1988
PRINTERSBBC Micro Computer SystemARCHIMEDES305 basic E699 (a)310 basic E799 (a)440 basic £2429 (a)Please ask for full detaft on add-ons andsoftware88C MASTER SERIES:AMB15 BBC MASTER 128K.. £356ADC06 Turbo 165C1021 Card . E115ADF10 Econet Card E40ADJ22 Ref. Manual ( £14ADJ23 Ref. Manua' Part II E14
UPGRADE KITS:1.2 OS ROM E15DNFS ROM £19BASIC II ROM )BBC 8) .... £22.50ADFS ROM £261770 DFS Kit £49Econet Kit (B&B,- I E55
(al(dl(dl
Ic)
(dl(dl(dlId)(dl(dl
ACORN ADD-ON PRODUCTS:Torch ZE? 100 £229 (a)512 2nd Processor E249 lb)IEEE Interface £265 101Teletext Adapter £95 di)32016 Co Proc E949 (a)X25 Gateway £2,175 (a)Ask for full detals on cur fug range of software
WORD PROCESSOR ROMs:VIEW 2.1 . £35 Id) VIEW 3.0 . E48Spelmaster. E49 Id) VIEW INDEX E12WORDW)SE £24 Id) WORDW1SE + E38
SPELLCHECK IIIWYSIW1G÷ E21 Id) £31INTERWORD E46 Id) EDWORD II £43
LANGUAGE ROMS:Micro Prolog E62 (Cl Microtext £52ISO PASCAL E51 (c) LOGOTRON . £55LOGO E46 (c) MACRON E33USP E39 (dl COMAL _ E43
Oxford Pascal £36
(C)(dl(dl
(dl(a)
Ic)Id)(dl(Cl
COMMUNICATIONS ROMS:TERMULATOR E25MASTER TERMULATOR £34.75 (dlCOMMSTAR E28MODEM MASIliH Ell (d)COMMAND E34 (dl
UTILITY ROMs:DOTPFIINT PLUS for FXRX compatiblesDOTPR)NT DUAL for MX rangeAcorn Graphics Extension Rom .. £28 Id)Merlin with 57 disc utility commands100 page manual £37.50 (c)
MULTIFORM Z80 2nd Processor for the BBCTris unique ZEO 2nd Processor miring 051.1,0,i; a it use of aMost any standard CP M soft.ware on the BBC micro. It is supplied with a number of different CP,M formats and includes autility to configure it to read other formats. This is particularly useful in environments where com-puters with different CR1.1 formats are used and the data cannot be easily exchanged betweenthem. t,tais powered (includes Pocket Wordstar & MS DOS RV/ utility) E249 151MS:DOS ReadWrite Utir E49 Ic)
META Version 3 ASSEMBLERAssembles 17 of the popular processors. Over 70K long program on two roms arid a disc andprovides complete Editing and Assembly faaties. It uses appropriate mnemonics for differentprocessors. Fully nestable macros. nestable conditional assembly IIFiaSEENDIF). modularsource code, true local and global labels. 32 bit labels and arithmetic. 30 ways to send objectcode arid 50 dectives.A powerful editor with many features. Send for deta,eli leaflet. E145 (b)
BBC DISC DRIVES5.25" Single Drive:1 a 400K 40,80T DS: TS400 £90 lbl PS400 with psu E101 Ib)5.25" Dual Drive:2 ki 400K 40:801 OS: TD800 ....1170 lal P0800 with psu E190 tat2 400K 40.1101 DS with psu and bull in monitor stand PD800P £209 (a)3.5" Drives:1 = itCAK EAT DS TS35 1 £69 Ibl PS35 1 with psu E85 lbl
400K BOT DS with frau-11335 2 £126 (b) P035 2 with psu E149 IblCombo drives (5.25" & 3.5"):
P0853 with integral PSU £175 (a) PD853P ,with integral PSU E195 (a)
3M FLOPPY DISCSIndustry standard floppy discs with a life time guarantee. Discs in packs of 10:
5Y4 DISCS 3% DISCS40T SS DD £6.50 (dl 40T DS DD. £8.00 (dl 80T SS DD £13.50 (dl80T SS DDE12.00 (dl 801 DS DD £11.00 (dl 801 DS DD £15.00 Id)
EPSONLX800 E179 (a) TAXAN KP815 ISO coil £159 (alFX800 £309 (a) KP9151156 col) £275 la)FX1000 E419 (a) BROTHER HR20 E349 lalEX800 E429 la) STAR LC10 E175 la)EX1000 E579 (al JUKI 6100 (Daisy Wheel) . ... E295 lalGO 3500 (laser) £1249 (a) INTEGREX )Colour) E529 (alL0500 £285 (a) NAT PANASONIC KX P 1081. E149 (a)LQ850 ISO coil ... ..... £489 (a) NAT PANASONIC KX P 3131. E245 (alLQ1050 1136 col) £599 (a) NAT PANASONIC KX P1082 . E172 fa)We hold in stock a large vanety of politer atrachmenrs, interfaces and COIISUMe.WeS.',tease write or phone for detaJs.
ACCESSORIESBUFFALO 32K Buffer for Epson printers £75 (c11; FX80 plus sheet feeder E129 Ib):EPSON Serial Interface: 8143 £30 (b): 8148 with 2K buffer E66 lb).EPSON Paper Roil Holder E1710): FXBOSO +,135 Tractor Attach £37 )b(: RX/FX80Dust Cover E4.50 (d): LX80 Tractor Unit £20 (c): L0800 Tractor Feed E47 (b).EPSON Ribbons: 1.1X:11X.FX80 £5: AIX,FIX,FX100 E10 (dl; LX80 £4.50 Id):
JUKI: Serial Interface E65 Tractor Attach. £149 (al; Sheet Feeder £219 (al:Ribbon £2.50 (al: Spare Daisy Wheel E14 (d).BROTHER HR20: Sheet Feed £229; Ribbons - Carbon or Nylon £3; Tractor FeedE116 (a); 2000 Sheets Fanfold with extra fine perf. 9.5" £13.50: 15" E17.50Inc Parallel Lead ES; Serial Lead £6 161.1Paratiet Lead 12m1 £12 (dl.
DISC ACCESSORIESSingle Disc Cable E6 Id) Dual Disc Cable E8.50 (di10 Disc Library Case £1.80 (c) 30 Disc Storage Box £6 (c)40 Disc I sinkable Box £8.50 (c) 100 Disc Lockable Box E13 (c)Roppiciene Drivehead Clearing Kit with 20 disposable cleaning kits 51-i" E14.5010): 3'2" EIS (dl
MONITORSMICROVITEC 14" RGB1431 Standard Resolution.. £179 (al1451 Medium Resolution £2.25 (al1441 Hi Res E359 lalMICROVITEC 14" RGB!PAL & Audio1431 AP Standard Resolution £199 (a)1451 AP Medium Resolution E255 hat
MICROV1TEC 20" RGEUPALAudio2030 CS std Res E380 (a)2040 CS Hi Res £675 (a)hretsubishi 14" RGB Med Res, 1138CIBMI
£219
TAXAN Supervision 620... E269 (a)TAXAN Supervision 625 . £319 lalTAXAN Supervision 770+
l..ith swivel stand! . E486 ial
12" MONOCHROME MONITORS:PHIUPS:
7502 Green Screen E 72 lal7522 Amber Screen E 79 (at4752 E 85 (a)
At PriFips Monitors supplied withsw vc-1 stand
BT APPROVED MODEMSMIRACLE TECHNOLOGY WS Range
WS4000 V21(23. WS3000 V22 bis Professional!Hayes Compatible, Inteifigent, Auto Dial/ As V22 and 2400 baud fug duplex £495 (a(Auto Answer) E129 WS3000)138C Data Lead £10 id)WS3000 V21/23 Professional WS2000 V21/1/23As WS4000 and with BELL standards and Manual Modem £92 1blbattery back up for memory .... £244 lb( WS 2000 Auto Dial Card E27 Id)WS3000 V22 Professional WS 2000 Auto Answer E27 (dlAs WS3000 V21/23 but with 1200 baud ful WS 2000 SK1 Kit £5 (dlduplex E379 fa) WS 2000 User Pon Lead E5 (dl
(Offer limited to current stocks)
SPECIAL OFFEREPROMs/RAMS
2764-25 £2.80 Id)27256 £6.00 Id)27512 £9.00 Id)6264LP-15 £6.00 (dl27128-25 (12.5 Vpp) £4.50 (dl27128-25 (21.0 Vpp) £6.00 (dl
LANGUAGES:6502 Assy Lang Prog8086 BookAcorn BCPL User GuideAcorn FORTHAcorn USPAcorn ISO P scat Ref Manual E10 00a -
Intro to COMAL £10.00Intro to LOGO E7.50Micro Prolog Ref Manual E10.00Introduction to Turbo Pascal £14.95Prog the Micro with Pascal £8.50The UNIX Book £7.50Unix Uses Guide E19.95Understanding Urtin E18.45
BBC MICRO GUIDE BOOKSBBC User Guide Acorn (15.00BBC Plus User Guide £15.00Drawing your Own BBC ProgramsE6.95Inside Information £8.95Math Prog in BBC Basic E7.95Toolbox 2 E10.95VIA 6522 Book 4 50
PROGRAMMINGIITILITYAdvanced Sideways Ram UserGuide E9.95Advanced User Guide (BBC) . . £1250Applied Ass.iLang on the BBC 19.95BBC Micro Sideways ROM's RAMSE9.95Guide to the BBC ROM £9.95Beginners Guide to W.? £7.95
BOOKSNo VAT on books; Carriage (c)
View 3.0 User Guide £9.00Viewstore E9.00
£19.95 Viewsheet £9.00£23.95 Wordwise Pius £9.95£15.00£7,50 SOUND & GRAPHICS:£7.50 Mastering Music £6.95
DISC DRIVE SYSTEMS:Advanced Disc User Guide .. £14.95Disc Book (3.50Disc Programming Techniques E7.95Disc Systems E6.95(tie Handling on the BBC E6.95
APPLICATIONS:Interfacing Proi for NC £6.95BBC and Sma'i Busiris E5.75
PROFESSIONAL SOFTWAREWordstar made easy .... £16.95Introduction to Wordstar £17.95Wordstar Handbook E11.95dEtase-11 for the first time user .E16.95Understanding dBase-Ill E22.95Multiplan Made Easy £18.95Multirnate Complete Guide .. E16.95ABC of LOTUS 123 £17.451-2-3 for Business £16.95Adv Tech in dBasellilll E22.95Mastering CRM E17.95GPM Bible £16.50Introducing CP,11 on BBC & 280 (9.95MS PC DOS Prompt .. E10.95
PROJECTS:Junior Computer Kit £86 (b)Housekeeper kit E58 (b)Elekterminal Kit (1980) £50 (b)ASCII Keyboard kit £75 (b)J C Books 1, 2, 3, & 4f6.90 (c) eaUniversal Terminal 16502) Kit E75 (b)Elekterminal Kit (19831 £70 (b)
PROGRAMMED ROPROJ
503-N Jnr. Computer Monitor2708 E 4.80
504 Disco fights 27013 E 4.80505 Chess Intelekt . 2 2716 £14.60506 J C Tape Monitor 2716 E 7.30507-N J C Printer Mon & PALE
2716E 7.30508 J C Bus Control 82523 . E 4.80510 150 MHz Fie(' Meter 2. 82S23
E 9.60514 Dark Room. Computer 2716 E 7.30
MS FOR ELEKTORECTS516 Taking Dice 2716 E 7.30521 CharGen & Video Routine forDOS Junior .. 2732 ÷ 2716 £16.40522 CharGen & video; Routine for ex-terved 2732 2.2716E24.00523 Char. Generator .. 2732 E 9.00524 Ouannsizer 2732 E 9.00525 Universal Term 2732 E 9.00526 Wind Dir Ind 2716E 7.30527 Ba.byrinth 2716 £ 7.30530 Dannosteel (face 2 x 2716 E11.00
ALL PRICESEXCLUDE VAT.Please add carriage 50p unless
indicated as follows:
lb1£2.50 (c/f 1.50) (d) £1.00
TECHNOLINEVIEWDATA SYSTEM
Tel 01-450 9764Using 'Nester type protocols.
For information and ordersavaaable 24 hours. 7 days
a week.
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riect5 CONTENTSDecember 1988Volume 14Number 162
IBC 1988p. 16
Pitch control for CD playersp. 21
38 CUMULATIVE INDEX 1988
Editorial
11 Towards the intelligent house
Special Feature MEW27 Computer -aided test equipment
by A.W. Moore, MA
Audio & Hi-fi21 PROJECT: Pitch control for CD players
42 PROJECT: LFA-150 - a fast power ampli-fier (final part)
Components
60 Background to E2PROMs
Computers,12 PROJECT: Bus interface for high -resolution
liquid crystal screens - Part 230 PROJECT: Autonomous input/output con-
troller - Part 162 PROJECT: Composite-to-TTL adaptor for
monochrome monitors
General Interest
67 Looking back: updates, applications andimprovements for recently publishedprojects
LRadio & Television
16 International Broadcasting Convention 1988a report from our Technical Editor
50 PROJECT: Colour test pattern generator64 Guiding those waves
by W.D. Higgins
I Science & Technology48 Chip set for Artificial Intelligence
by Leon Clifford
Test & Measurement58 REVIEW: Part 12 - AF Signal Generators (6)
by Julian Nolan
L Information
Nev.'s 26, 29, 36, 57, 61; New products 41,47; People 49; Corrections 55; New literature56; Events 66; Readers' services 69
Guide lines
Switchboard 70; Buyers' guide 74; Classifiedds 74; Index of advertisers 74
I
Computer -aided test equipmentp. 27
Chip set for Alp. 48
In next month'sissue: MIDI control
unit Thyristor revol-
ution control CD electronics Audio measure-
ments bycomputer
Fax converterfor Atari ST
Practical filterdesign - anew series
Low-cost devel-opment systemfor M6805
113131.133.31 33331
£4 rti
Front coverThe design of microcir-cuits is becomingmore challengingevery year. Plessey'sRoborough siliconwafer fabrication plantin Plymouth producesCMOS chips that re-quire much less powerthan other types andare particularly suitedto telecommuni-cations, computers,traffic controls androbots. Completedwafers are subjectedto comprehensivetesting to guaranteeperformance and toprovide data for pro-cess control.
EE
December 1988
1989CATALOGUE
OUT NOW! 100 BIG PAGES!Huge range at rock -bottomprices. Send for your copynow. ONLY £1.00.
NEW THIS MONTHLCD display:Z4115 8 digit 12.7mm high LCD by DataImage. 14 segment, so letters as well asdigits can be formed. List £15+
Our price £4.50
Keyboards:Z8848 Alpha numeric + separate numericKeyboard. 104 keys . 11 chips. 442 x
E12.00175mm
24116 24 way (8 x 3) membrane keypad. FLASH UNITSLarge 1200 x 90mrn) area - they were Z4100 Brand nevi, made for Hanimex.used in a teaching aid. Overlay template 56 x 30 x 18mm. Apart from xenon tubeand pinata supplied. £3.00 and driver circuitry, there is a sub -min 3V
relay. With data E2.75Power supplies:24117 Special low price switch mode 28837 DUAL SHEET FEEDER. Brand newPSU. SOW unit on PCB 160 x 100trim. creakdown unit. Contains 3 x 1 2V step -Mains input. outputs 5V 0 5A; +12V 0 per motors (48 step) plus driver panel withIA: -12V 81A. List E40+ £9.50 4 x T1P115, 4 x TIP110, LM3302. 2 x
7407; 2 solenoids, buzzer, microswitiiZ4113 BBC Computer PSU (early models) ches, control panel, 2 optocouplers plusSteel case 158 .72 x 55mm, 2m long lots of gears and mechanical bits.mains lead, rocker switch, fused. Out- £24.95+E3 Can.puts: +5V 02.5A; -5V :0100mA.f 3.95 Full details plus plc on Bf1.40. AU parts
available separately e.g.:24112 Another switch mode PSU. Samesize as 24117. Outputs 24V it 1.7A: 12Vit 0.84 E9.95
24089 Stepper Motors £6.00
REMOTE CONTROL far Toshiba VCR. 165* STAR BUY * x 55 25mm case has 7 push buttons.
GREEN SCREEN HI-RES 12" MONITOR slider pot and edge pot. 6mm long 8 coreCHASSIS lead. PCB had 4001 and 4582 plus fewBrand new and complete except for case,the super high definition (1000 lines atcentre) makes this monitor ideal for corn-
other bits. £1.99
24081 CB Aerial eliminator. Black steelOuter applications. Operates from 12V DC case 77 x 70x30 for using car radio aerialat LIA. Supplied complete with circuitdiagram and 2 pots for bnlliancelcontrast. with CB. Has 2 x 500pF trimmers,
switches, con etc + 2 leads approx. 2mplus connecting instructions. Standard in-put from IBM machines, slight mod(details included) for other computers.
long. Originally E7.95 Our price £2.00
Only £24.95 + £3 tart 24080 AMICB convener. Enables all CSchannels to be picked up on MV..
MONITOR INTERFACE KIT 85 x 70 50crun £4.50Enables our hires monitor (above) & mostothers to be used with virtually any corn- LM358's for 5pfouter. PCB E3.00 Z347 4 a LM358 op amps surfaceComplete set of on -board components + mounted on ceramic substrate, easily re -regulator & heatsink £9.95 moved. 5 panels for £1.00Suitable transformer for interface andabove monitor E5.31
i ++t ++re,--- -., . -..
- -:- : '
JOYSTICKS
2004 Skeleton Joystick, switch type.ie
- 7 7 7 Good quality, made by AB. Brass spindle-'' " ' , r : has 44mrh long black plastic handle at-tached. Body holes.These really are a fantastic bargain!!
ONLY £1.002810 KEYBOARD Really smart alphanumeric standard qwerty keyboard with Z615 BBC joystick. Internal resistors giveseparate numeric keypad. from IC L's 'One the required voltage levels. 2 rue buttons.Per Desk'. Nicely laid out keys with good Rubber suction feet. 120 x 110 x 155.tactile feel. Not encoded - matrix outputfrom PCB taken to 20 way ribbon cable.
£3.00
Made by Alps. Size 333 x 106mm. 73 28831 Dragon Joystick. Made by Dragonkeys E8.95 Data. Hand held with fire button, 2m lead
Back in stock 28833 Tatung casedkeyboard VT4100. 85 keys inc sep.numeric keypaz. 450..255x65125.
,:, ith 5 pin DIN. Uses 2 x 100k pots E3.00
E14.95 SOLDER SPECIAL!!COMMODORE INTERFACE * 15W 240V ac soldering ironZ030 Plugs into user port on C64 and * High power desolder pumpg;ves serial output to 5 pin plug. Uses * Large tube solder27256, 6850 plus LS & CMOS E5.95 ALL FOR
SPEECH SYNTHESIZER KIT £7.952315 All parts inc. PCB to make a speechsynth for the BBC micro £4.99
MICRO PANELS2316 De -luxe version -also includes Z620 65000 Panel. PCB 190+:45 be-V2I 5 case, lm 20W cable plus connector lieved to be from ICL's 'One per Desk'
£7.99 computer containing MC68008P8 18MHz1618 bit microprocessor, + 4 ROM's, all
VIEWDATA LTU in skis; IMP5220CNL. 74HCT245, 138.Z697 Interface Panel 166 a 150 with LS08. 38 etc £5.003 x LM324. LM339. LM393, 4066, 11transistors. 3 reed relays etc. 3m leadwith EFT plug attached. Supplied withcomprehensive data and .... £2.90
2625 321c Memory Board. PCB 170x 170with 16 2It .8 6116 static RAM's. Also3.6 V 100 mA memopack nicad. 13 other
SWITCHED MODE PSUAstec type AA7271. PCB 50 x 50rnmhas 6 transistor cct providing currentoverload protection. thermal cut-out and
HCILS devices. 96w edge plug, 8 way DILswitch. R's. C's etc E4.80
2345 OPTICAL SHAFT ENCODER Sirnilarexcellent filtering. Input 8:24V DC. Out-put SV 2A. Regulation 0.2%.
£6.00
to RS631-632. but 80% cheaper! £8.50
TELETEXT PANELZ037 265 x 145min by GEC. Uses
Z026 Astec 65 wan unit. 1151230V ac 8085A, 8155, 8255A. 8251. 8212 all byinput. Outputs + 5V GA: + 12V 1.5A; Intel. 2 x 2114, 2 xTC5501 + custom+ 12V, 2.1A; - 12V 0.25A. PCB 197 x chips + 10 others. Nicad back up. New'.07 mm £24.95 £9.90
AS or,ces include VAT: just .i:: :: .03 P&P.No mat. CWO or ..._:.s C'' : : :.cars fromTUM schools etc. vic'::-: - . : :e chargef: 10. OUT shop r , :: ...of components add isow 9-5.30 M.: ,.:,-.. ...._ -_ ,.. _ ,-e us!!! Send 54E ..
GREENWELD latest Ba'2.1;1 Um--443E Millbrook Road Southampton
ELECTRONICCOMPONENTS
SO 1 OHX Tel (0703) 772501 783740FAX 10703) 787555; Entail 72: MAG36026; TELEX 265871 MONREF Gquoting 72: MAG 36026
.q1-1) EL W1TRANSFORMERS FROM
The UK Distributor for theStandard Toroidal Transformers
- 106 types available from stock Sizes from 15VA to 625VA
- Dual 120v primaries allowing 110 120vor 220 240v operation
STEEL DISHEDWASHER
OUTERINSULATION
SECONDARYVOWING
INSULATION
PRIMARYWINDING
CORE
END CAPS
NEOPRENEWASHERS
TYPE SERIES SEC RAC TYPE SERIES SEC HMSVOLTS CURRENT NO. VOLTS CURRENT
15VA 03010 6.6 1.25 160VA 53011 9.9 8.89
E9.150301103012 9*9
12+120.830.63
53012£16.10 53013
12+1215+15
6.665.33
03013 15.15 0.50 53014 18+18 4.4403014 18.18 0.42 53015 22+22 3.6303015 22.22 0.34 53016 25.25 32003016 25+25 0.30 53017 30+30 2.6603017130; 30.30 0.25 53018 35+35 2/8
3OVA 13010 6+6 2.50 53026 40.40 2.00
£10.35 ;Ell; 9.812.12
1.661.25
5302853029
110220
1.450.72
13013 15.15 1.00 53030 240 0.6613014 18.18 0.83 225VA 63012 12+12 9.3813015 22+22 0.68 a..., an 63013 15+15 7.5013016 25.25 0.60 `". 63014 18.18 6.2513017 30+30 0.50 63015 22422 5.11
50VA 23010 6+6 4.16 63016 25.25 4.50
a 1 Z5 Ng;; 9+912+12
2.772.08
6301763018
30+3035+35
3.753.21
23013 15+15 1.66 63026 40.40 2.8123014 18+18 1.38 63025 45+45 2.5023015 22.22 1.13 63033 50+50 2.2523016 25+25 1.00 63028 110 2.0423017 30+30 0.83 63029 220 1.0223028 110 0.45 63030 240 0.9323029 220 0.22 300VA 73013 15+15 10.073030 240 0.20 7301473015 18+18 8.33
813VA 33010 6.6 6.66 £19.20 22+22 6.8233011 9+9 4.44 73016 25+25 6.00
£12 .9033012 12.12 3.33 73017 30+30 5.0033013 15.15 2.66 73018 35.35 4.2833014 18.18 2.22 73026 40.40 3.7533015 22.22 1.81 73025 45+45 3.33.33016 25*25 1.60 73033 50+50 3.0033017 30-30 1.33 73028 110 2.7233025 110 0.72 73029 220 1.3633029 220 0.36 73030 240 1.2533030 240 0.33 500VA 83016 25+25 10.0
l2OVA 431310
£13.70 1:111;
6-69.912+12
10.06.665.00
83017£25.35 8301883026
30+3035+3540+40
8.337.146.25
43013 15+15 4.00 83025 45+45 5.5543014 18+18 3-33 83033 50+50 5.0043015 22+22 2.72 83042 55+55 4.5443016 25+25 2.40 83028 110 4.5443017 30.30 2.00 83029 220 22743018 35.35 1.71 83030 240 2.0843028 110 1.09 625VA 93017 30+30 10.414302943030
220240
0.540.50 027.915
93018: 35+3540+40
8.927.81
93025 45+45 6.9493033 50+50 6/59304293028
55+55110
5.685.68t
93029 220 2.84Prices include VAT and carriage 93030 240 2.60
Quantity prices available on requestWrite or phone for free Data Pack
Jaytee Electronic Services143 Reculver Road, Beltinge, Herne Bay, Kent CT6 6PL
Telephone: (0227) 375254 Fax: 0227 365104
Please mention ELEKTOR ELECTRONICS when contacting advertisers
EE
December 1988
A Wolters Kluwer CompanyEditor/publisher: Len SeymourPersonal Assistant: L. VousdenTechnical Editor: J BuitingAdvertisement executive:Pauline O'Rourke
Editorial offices:1 Harlequin AvenueBRENTFORD TW8 9EWEnglandTelephone: 01-847 2618 (National)or +44 1847 2618 (International)Advertising: 01-847 2619Telex: 917490 (elektr g)Fax: 01-847 2610
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Elektor Verlag GmbHSiisterfeld-Strafe 255100 Aachen - West GermanyEditor: E J A KrempelsauerElektor EPEKaraiskaki 1416673 Voula - Athens - GreeceEditor: E Xanthoulis
Elektor Electronics PVT Ltd.Chhotani Building52 C, Proctor Road, Grant Road (ElBombay 400 007 - IndiaEditor: Surendra lyerElektuur B.V.Peter Treckpoeistraat 2-46191 VK Beek - the NetherlandsEditor: P E L Kersemakers
Ferreira & Bento Lda.R.D. Esteftinia, 32-1°1000 Lisboa - PortugalEditor: Jorge GonsalvesIngelek S.A.Plaza RepUblice Ecuador2-28016 Madrid - SpainEditor: A M Ferrer
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Typeset & composed in theNetherlands by GBS, Beek (L).Printed in the Netherlands byNOB, Zoetert.voude.
Copyright `z.E-s.. 1988 Elektuur B.V.
ABC
TOWARDS THEINTELLIGENT HOUSENearing the end of the year, it is, perhaps, instructive (and fun) to take the re-cent remarks by British Telecom's chief executive and chairman, Mr lainValiance, a little further and take an inspired look at what changes we arelikely to see in our domestic environment of the future.
Homes will be equipped increasingly with a domestic computer terminal (putin by the builders like a sink unit). This will control the central heating, hotwater supply, cooker, video, lighting, and so on. Eventually, there will be afully automated kitchen that will carry out most of the irksome tasks like iron-ing and washing up.
This domestic computer will be controlled via the public telephone network.The conventional telephone will be replaced by a wristwatch type, so that thehome can be controlled from wherever you are.
The conventional door lock will disappear and be replaced by tone -detecting electronic locks that respond to the householders' voices.
Although the combustion -engine -driven car will not disappear for a long timeto come, there will be an increasing number of electric cars. New, small,large -capacity batteries will make these a commercially viable proposition.All cars will be fitted with a large number of electronic gadgets to take thetediousness out of driving. They will have microprocessors that control fuel in-jection, gear changing, spring rate, vehicle height, shock absorber damping,and others. All cars will be equipped with anti -brake -lock systems and sensorsthat actuate the braking -system when you get too close to the car in front.
Increasingly, shopping will be done from home with the aid of video -telephones and electronic fund transfer.
Home entertainment will be based on digital equipment, and probably beinteractive, allowing subscriber selection of high -definition, 3D, large -screen,video, television, and music via common networks.
Television and video communications will dominate the home even morethan they do now. With more and more satellites hovering above the equator,signals from them will be received via dishes not much larger than a dinnerplate. The screens will be linked in with the telephone network so that allcommunications will be face-to-face.
Cellular radio systems, linked world-wide by satellite systems will be com-monplace so that anyone can communicate with anybody else whereverthey may be.
Paraplegics may be able to walk again with the aid of electrical stimulationof their muscles. These stimuli will come from pressure, angular, and acceler-ation sensors on their limbs.
The deaf will have portable videophones in which a microprocessor displaysthe incoming telephone speech on to a screen.
Electronic devices will continue to get smaller and faster, although the size offinished products will, of course, still be dictated by the needs of the user.Slowly but surely, silicon ICs will be replaced by gallium -arsenide chips, andthese, in turn, will be superseded by neural or optical devices. The density ofthese devices will be staggering by current standards.
The future certainly looks exciting, the more so for those of us who play an ac-tive part in the wonderful world of electronics!
EDEecembe 1988
BUS INTERFACE FOR HIGH -
RESOLUTION LIQUID CRYSTALSCREENS
ConstructionThe LC screen interface is constructedon a double -sided, through -platedprinted circuit board (see Fig. 4). Thetrack layout is not given here becausethis PCB is virtually impossible to makeother than from films, while through -plating equipment is usually onlyavailable in a professional workshop.The size of the ready-made. PCB is suchthat it can be attached to the controllerboard of the LM40001 unit with the aidof 4 spacers. The connection betweenthe interface board and the existing con-troller board is conveniently made in ashort length of 10 -way flat ribbon cable.The mounting of the standard -sizedcomponents on the board should notpresent difficulties. Only the controller,ICs, deserves special attention. This ICis housed in a 64 -pin flatpack enclosurefor surface mounting, with pins in a1 mm, rather than a 0.1 in., raster. Use alow -power soldering iron with a small tipto solder the terminal pins of the con-troller direct on to the relevant coppertracks. Work very carefully, and usedesoldering braid to remove solder whena short-circuit is made between adjacentpins. As to orientation of the controllerchip on the board, stick to the compo-nent overlay, because pin 1 is not locatedimmediately next to the bevelled edge ofthe enclosure!Connector Ki, a 40 -way PCB headerwith eject handles, is secured on to thePCB by means of two small bolts andnuts. The pinning of K1 makes it poss-ible to use a direct, pin -to -pin, connec-tion, in flatcable, to the expansion con-nector on the BASIC computer 0). Forother computer systems, it is necessaryto provide a do-it-yourself connectionbetween Ki and the bus (see Tables 3aand 3b). Whatever connection is used,the total length of the cable between thecomputer bus and ICI should not exceed30 cm or so.
Programming the LC screeninterfaceSoftware for producing ASCIIcharacters on the LC screen is relativelysimple to produce thanks to the con- cessing of individual bits loaded from the screen RAM.
Part 2
Table 2 Interface configuration data
Processor Z80'(MSX)
6502 IBM-PC' ELEKTORBASIC COMPUTER
Jumpers A,C,E,G,(KI,Q,T is,,B,H,L,P,S C,D,F,M,Q C,D,F,M,P,SMapping I/O MEMORY I/O MEMORY
k1
I X0X1
X2A3 -A5A6 -A7
A8 -A15
S1
S2
S3S4 -S6
S7 -S8
S8-818
M1
--A3 -A5A6 -A7
-
offoffoffXX
(MSX ON)
---
A3 -A5A6 -A7
A8 -A15
offoffoffX
X
X
AEN I onA3 X
A4 ' X
A5 -A7 on
A8 -A9 i off
- -
---
A3 -A5A6 -A7
A8 -A15
offoffoff
I X
X
X
Address rangeMSX 0-3FH
else 00-FFHsystemdependent
300H-31FH system -
dependent
PH12.DIR -432RST-NRSTWR- RI:1MR
XO-AENRST-RESET
-X2-IOREQXi-MIRST- RESET WAIT -10 CHRDWAIT -WAITfor MSX:PH12/DIR1-SW1(---SW2
RD-IORDWR-IOWR
-BUSDIR
*IC6, S9 -S16 and R2 may be omitted
Display mode phiopmlaymdpauta RAM Uquld crystaldisplay panel
HP
07 115 bs b4 b3 b2 In bo
Character Character code Start
II i1
. iI I lll
. I . (
A B C
I-"A 1display (8 bits) address 011 010 01010 1
011000010
Hp: 6.7 or 8 dots
4Hp 4
t7.b7 b5 b5 b4 b3 1)2 bi bo
...to
t4
GraphicDisplay pattern Start
1131=1117.7=1"A
8 dots 8 dots(8 bits) address -n. Ot 0 1 0 1 011i1 1 1 1 1 1i1
Hp:8 dots
Fig. 6. Difference between character (text) display and graphic display mode as regards pro-
EE 111December 1988
0135 DB4 DB3 DB2 DB1 DBO
0: Character mode: Graphic mote
00 :Culsor OFF01: Arson ON10 :Carsor OFF , character balk11:Cursor brink
1 : D3i is the hit to specify the master chip or slavechip when mattple chips of Ii061830 are used.
{0: Display OFT (display off without clearing the
Lrefresh memory contents)
1: replay ON
{0: Internal character generator R044 of the 11061EGO1: External character geserator PCht
840074-12
Fig. 5. Bit assignment in the MODE register of the LCD controller.
..
Table 3a
SLOT i SIGNAL DESCRIPTION
PIN NO. NAME I/O 1 DESCRIPTION
1
2
3
4
5678
910
11
12131415161718192021
22232425262728293031
323334353637383940414243
44,4645,47
484950
CS 1 000.0
0I I
I
01 1
00000-0000
j o0000
1 01 0
0I 0
000
(JO
I/OI/OI/OI/0I/0I/OIi0-0----
I-
ROMROMROMSlotsignalReservedRefreshWaitInterruptFetchThisternalis
is
I/OMemoryWriteReadSystemReserved
1 '
1..
EGround
Insertiremove÷÷12
i. Sound-12
4000 - 7FFF select signal 1128K18000 - BFFF select signal (128K)4000 - BFFF select signal 1256K)
selected signal. - Fixed selectfor each slot.
for future usesignal
for signal to CPU twired-OR)request sional
cycle signal of CPUsignal controls the direction of ex-
data bus buffer when the cartridgeselected. It is low level when the datasent by the cartridge.
request signalrequest signal
signalsignal
reset signalfor future use
Address bus
Data bus
protection, if fitted5 V power supply
V power supplyinput 1-5 dbm)
V power supply
CS2CS12SLTSL
RFSHWAIT
INTMi
BUSDIR
IORQrv1ERQ
WRRD
RESET
A9A15All
j A10A7A6
Al2ABAl4A13AlAOA3
aA2A5A4D1
DO
D3D2D5D4
I D7DO
GNDCLOCK
GNDSW1, SW2
÷ 5 V+12 V
SOUND IN-12 V
Input and output refers to MSX computer
Table 3b Signal functions on IBM bus
Signal name Signal Name
GND B1 Al -10 CH CF.- RESET DRV 82 A2 +117-5V 63 A3 +D6-1R02 84 A4 -+DS-5VDC BS AS +D4-DR02 86 AS +D3- 12V 67 A7 +D2Reserved B8 A8 +01+ 12V 69 A9 +DOGND 810 MO +IX) CH RDY- MEW., 811 A11 +AENMEMR 812 Al2 +A19
B13 A13 +A18-IOR B14 A 1 4 -A17-DACK3 815 Al 5 +A16-DRQ3 816 Ai 6 +A15-DACK1 817 A17 +A14-+DRQ1 618 Alb +A13-DACKO 819 A19 ÷Al2CLOCK 820 A20 +A11+11107 B21 A21 +A10+IRQ6 B22 A22 +A9
IRQS 823 A23 +A8- IRC14 824 A24 +A7
825 A25 +A6-DACK2 626 A26 +A5+TiC 627 A27 +A4+ALE 628 A28 +A3+5V 829 A29 +A2+0SC 830 A30 +AI-CND 831 A31 +AO
troller taking over the task of generatingthe dot patterns for the characters.Briefly recapitulating what has been saidin the above description of the circuit,the five registers of Table 1 are eitherread or write locations. Four of theseregisters control the HD61830B, andone, LATCH, ICit, whose output statedetermines the contrast (bits 0 to 3), theselected 4 Kbyte screen RAM (bit 6), andthe selected add-on character font (bit7).Table 4 shows that the controller chip of-fers quite a few programmable func-tions. Its basic operation will be dis-cussed with a few examples as guidancefor further developments.To start with, it is seen that the chip has14 registers for storing differentparameters. One register, number 14,returns the busy flag, which is logic highfor about 15 pis after receipt of a con-troller command. The controller can nothandle a new command as long as thebusy flag is active. Busy can be readfrom the databus via register CTRL -RD(control read). It will be clear that thereis very little point in using this flag inBASIC, because the relatively low pro-cessing speed of this programminglanguage makes it impossible anyway tosend a new command to the controllerbefore this has deactivated the busy flag.Machine code programmers, however,are well advised to have the controlprogram read and process the busy flag.
Before any character can be displayed onthe LC screen, the controller must be in-
14 EE
December 1988itialized. For the following description itis assumed that an LC screen TypeLM40001 is used. For other types, therelevant data sheets should be examinedto analyse the register assignment.The first 4 registers in the HD61830Bshould always be loaded. Table 4 showsthat register 0 is the mode control. Thevarious options available are given inFig. 5. Writing to a register is done intwo passes: first, load the register num-ber in address control -write (CTRL-WR), then write the relevant data to ad-dress data -write (DATA-WR). TheBASIC listing of Fig. 9 illustrates thisprocedure. The subroutine starting atline 1000 loads variable DA in registerCTL. The other four registers are loadedin a similar fashion.Lines 60 to 100 in the demonstrationprogram hold the the data for loadingcontroller registers RO up to and includ-ing R4. The corresponding screen set-tings form a usable default configura-tion, and are best copied for initial ex-periments in programming the LCscreen. It is possible to read the data atthe cursor address. To do this, first loadthe required cursor address in register 7(LS byte) and register 8 (MS byte). Thenperform a dummy read via addressDATA -RD. Next, read the data`underneath' the cursor from addressDATA -RD. Any subsequent read com-mand returns the data at the next ad-dress in the screen memory. A new dum-my read operation is not required untilthe cursor address is altered by the con-trol program.
When the LC screen is set to graphicsmode, all graphics data to be displayed
AllMOA9
A8
A7
0
0
0
0
0
0
0
0
0
1
A6 A5 A4 A3 A.2 At AO D7D613504D3D2D1D0 D7 C6 D504 D3 D201 DO
0 0 0 0 0 0 0 1 1 1 1 0 0 0 0 0 1 1 1 0 0 0 00. 0 0 1 1 0 0 0 1 0 0 0 1 0 0 0 1 0 0 00 0 1 0 1 0 0 0 1 0 0 0 1 0 0 0 1 0 0 00 0 1 1 1 1 1 1 0 0 0 0 1 0 0 0 1 0 0 00 1 0 0 1 0 1 0 0 0 0 0 1 0 1 0 1 0 0 00 1 0 1 1 0 0 1 0 0 0 0 1 0 0 1 0 0 0 00 1 1 0 1 0 0 0 1 0 0 0 0 1 1 0 1 0 0 00 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 01 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 01 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 01 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 01 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 01 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 01 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 01 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 01 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 1 0 0 0 0 1 1 1 1 1 0 0 00 0 0 1 0 0 1 0 0 0 0 00 0 1 0 0 0 1 0 0 0 0 00 0 1 1 0 0 1 0 0 0 0 00 1 0 0 0 0 1 0 0
Fig. 7. Illustrating the compiling of a dot pattern matrix to be loaded into an add-on fontEPROM.
corresponds to dot information writteninto the screen memory. The controller isswitched to graphics mode by program-ming a logic 1 for bit 1 in the moderegister. The graphics information canthen be written direct to the screen mem-ory. Data can be loaded as separate bytesafter loading the start and cursor ad-dress, similar to the procedure followedin the text mode. Before sending the
databyte it is, however, necessary to callregister 12 via CTRL-WR, and thenwrite the data to DATA-WR. The dotusage of the controller is shown inFig. 6. The listing of Fig. 9 may alsohelp to analyse the operation of thegraphics mode in further detail. LikeASCII characters, dot information canbe read back from the display - write13 to CTRL-WR, then perform a dummy
Table 4 HD61830B Register Overview
Register DataCTL FLW RS DB7 DB4 D83 DB2 DB1 D80 Function FM RS DB7 DB6 DB5 I DB4 I DB3 I DB2 I OB1 I DBO0 0 1 0 0 0 0 0 Mode control 0 0 0 0 Mode data1 0 1 0 0 0 0 1 Verticalthorizontal character pitch 0 0 (Vp - 1) B I 0 I (HP -1) B
2 0 1 0 0 0 1 0 Number of characters perline number of bytes 0 o o (FIN - 1)B
3 0 1 0 0 0 1 1 Number of vertical dots 0 0 0 (NX - 1) B4 0 1 0 0 1 0 0 Cursor position 0 0 0 010I0I (CP - 1) B
8 0 0 1 0 0 0Display starting address (leastsignificant) (Lower)
0 0 Address data
9 0 1 0 1 0 0 1Display starting address (mostsignificant) (Upper)
0 0 0 0 0 0 Address data
10 0 1 0 1 0 1 0 Cursor address (least significant) 0 0 Address data
11 0 1 0 1 0 1 1Cursor address (most significant)(Upper)
0 0 0 I 0 1 0 I 0 Address data
12 0 1 0 1 1 0 0 Refresh memory write 0 0 Character code/bit data13 0 1 0 1 1 0 1 Refresh memory read 1 0 Refresh memory data14 0 1 0 1 1 1 0 Bit clear 0 0 0 0 0 0 0 (BN) B15 0 1 0 1 1 1 1 Bit set 0 0 0 0 0 0 0 ION) B14 - - - - - - - BUSY signal read 1 1 BF
read, and, finally, read the bit configura-tion at address DATA -RD.
EE
December 1988
Adding a character setAs already stated, the controller can usedata in an external EPROM to form anadditional character set. Figure 7 showshow the controller converts EPROMdata into dot patterns on the LCbackplane. Using the information givenin the figure, a simple computer programmay be written to compile a user -definedcharacter table in the EPROM. Alterna-tively, build the table manually by draw-ing the character outlines on squaredpaper. A ready -programmed EPROMwith two additional character sets isavailable as stated in the Parts List.
Reference:(" BASIC computer. Elektor ElectronicsNovember 1987, p. 24-31.
Fig. 8. Completed interface board fitted onto a Sharp L.M40001 LC screen module.
10 REM SHARP LM40001G WITH HD61830B CONTROLLER. 8.50 CHAR'S; 8.8 MATRIX20 DAWR=OFFF8H30 CTLWR=OFFF9H40 LATCH=OFFFCH50 REM MODE, CHAR. PITCH, s OF CHAR'S, MIX, CUR60 DATA 38H70 DATA 77H80 DATA 4990 DATA 31100 DATA 7110 XBY(LATCH)=B: REM CONTRAST120 REM INITIALIZE HD61830B130 FOR CTL=0 TO 4140 READ DA: GOSUB 1000150 NEXT CTL160 REM SET DISPLAY STARTADDRESS170 STRTADR=0: GOSUB 2000180 REM SET CURSORADDRESS190 CURADR=0: GOSUB 3000200 REM CLEAR DISPLAY210 GOSUB 4000220 REM SET CURSORADDRESS230 CURADR=0: GOSUB 3000240 REM WRITE MESSAGE250 CTL=OCH: REM ...CHARACTER CONTROL260 FOR X=0 TO 255270 DA=X: GOSUB 1000280 NEXT X290 STOP: REM STOP BEFORE GRAPHICS DEMONSTRATION300 REM ERASE DISPLAY310 XBY(CTLWR)=0: XBY(DAWR).32H320 CURADR=0: GOSUB 3000: STRTADR=0: GOSUB 2000330 FOR J=0 TO 63: FOR I=0 TO 49: XBY(CTLWR).12: XBY(DAWR)=0: NEXT: NEXT340 XBY(CTLWR)I0: XBY(DAWR)=32H350 REM DRAW PATTERN360 STRTADR.0: GOSUB 2000370 FOR L=0 TO 15380 K=O: J=31390 FOR I=L TO L-3 STEP -1400 IF 1(0 THEN 520410 FOR X=0 TO 7 STEP 2420 CURADR=I+J50: GOSUB 800430 CURADR=CURADR-50: A=2(7X)2(6-X): GOSUB 800440 CURADR=49-IJ50: GOSUB 800450 CURADR.CURADR-50: GOSUB 800460 CURADR=49-I+(J1+X2X.16)50: GOSUB 800470 CURADR=CURADR50: A=2+X+2(X1): GOSUB 800480 CURADR=I+(J+1+X2+K16)50: A=2(7 -X)2(6 -X): GOSUB 800490 CURADR=CURADR50: GOSUB BOO500 J=J-2510 NEXT X520 K=K1530 NEXT I540 NEXT L550 REM WRITE LCD IN GRAPHIC MODE570 FOR M=0 TO 2580 I=M+3+21590 FOR J=16 TO 44 STEP 4600 FOR L=0 TO 2610 READ A620 FOR K=0 TO 3630 CURADR=I+L(K+J)50: GOSUB 800640 NEXT K650 NEXT L660 NEXT J670 NEXT M680 END: REM END800 GOSUB 3000: XBY(CTLWR)=12: XBY(DAWR)=A: RETURN1000 REM WRITE CONTROL AND DATABYTE1010 XBY(CTLWR)=CTL1020 XBY(DAWR)=DA1030 RETURN2000 REM SET DISPLAY STARTADDRESS2010 CTL=8H2020 DA=STRTADR.AND.00FFH2030 GOSUB 10002040 CTL=9H2050 DA=STRTADR/2562060 GOSUB 10002070 RETURN3000 REM SET CURSORADDRESS3010 CTL=OAH3020 DA=CURADR.AND.00FFH3030 GOSUB 10003040 CTL=OBH3050 DA=CURADR/2563060 GOSUB 10003070 RETURN4000 REM CLEAR DISPLAY4010 CTL=OCH4020 XBY(CTLWR)=CTL4030 FOR I=0 TO 3994040 XBY(DAWR).20H4050 NEXT I4060 RETURN5000 DATA 15,0,0,15,0,0,15,0,0.15,0,0,15,0,0,15.0,0,15,0,0,255.255,155010 DATA 240,255,0,15,0,15,15,0,0,15,0,0,15,0,0,15,0,0,15,0,15,240,255,05020 DATA 255.255.0.i5,0.15.15.0.15.15.6.15.15.0,15.15,0.15.15,R.15.255.255,0
860074.9
Fig. 9. Graphics demonstration mgt.= for the Elektor Electronics BASIC computer plusLC screen interface described here (LM40001). The program halts at line 290 - type CONTto continue the graphics demo. XBY(...) is an output instruction, and ** stands for mathe-matical squaring.
EE16
DINTERNATIONAL BROADCASTCONVENTION 1988
The International Broadcast Convention held in Brighton lastSeptember gave visitors a unique opportunity to see the future
trends in audiovisual equipment for consumer as well asbroadcaster. This year's IBC concentrated mainly on technical
aspects of High -Definition Television (HDTV), which will be with us inthe not too distant future. Since HDTV equipment represents pro-fessional and consumer markets worth billions of pounds, it is notsurprising that many manufacturers are eager to grab whatevershare they can get. Once again, however, there is the danger of
the radio & TV world being split in two or even more campsowing to incompatible standards. And once again, Oriental and
European electronics giants have found the UK market a finebattleground.
1988
For the thousands of professional broad-casters around the world, a visit toIBC88 at Brighton enables planning atleast five years ahead in equipment ex-penditure. For the consumer, the show isan impressive display of the audiovisualequipment of tomorrow. The futuristictrend can be quite confusing, however.For example, the S- (super) VHS videosystem, for which consumer equipmenthas been introduced recently, hardly re-ceived attention at IBC88. Looking atthe latest technology on display duringIBC88, it is good to bear in mind thatthe industry is way ahead of the con-sumer market.
As already stated, this year's Inter-national Broadcast Convention focusedheavily on HDTV. Although this reportis not intended to give a technicalbackground to this new TV system, ageneral background will be given below.High -definition television is basically amove to the 'cinema at home'. Currentsatellite technology and the use of im-proved TV standards, such as MAC,have made it possible to achieve betterresolution and a more natural viewingaspect ratio by doubling the number oflines in a TV picture. The possible evol-ution of HDTV is shown in thesimplified drawings of Fig. 1(developments in sound technology arenot shown).The MAC transmission format is essen-tial to HDTV. A number of research in-stitutions have worked on the develop-ment of an extended version of MAC,HD -MAC, capable of handling the highdata -rates required for HDTV pictures.Current technology enables these to be
A report from our Technical Editor
transmitted via D -MAC (important forthe UK BSB project) and D2 -MAC (im-portant for the West -German andFrench DBS projects).
T)0
rte,
-1. Yid
SET -TOP DEC*OERCV= We
P--100003Oirr
as
LAC
TV-.:l
wanner/ FL. t.alcirVAC 7-101
:ATV it:imamEi
F.TCESLA
WeA-crna.i-LTI toc.no,
VI :4
=sr
Fig. 1. Simplified drawings showing thepossible evolution of television transmissiontechniques from the existing situation towide screen HDTV.
Obviously, HDTV can not be introducedjust like that, making consumer equip-ment obsolete overnight. A gradual in-troduction of the new standard can onlygo by way of initial compatibility withexisting equipment. Standards con-verters will enable the current TV setwith 4:3 aspect ratio to last well into the1990s, alongside wide-screen types.Market researchers, however, referring tothe commercial success of colour TVand the VCR, are confident of the fastacceptance of HDTV monitors and an-cillary equipment, pointing out that con-sumers are ready to but new equipmentif this offers a significant quality im-provement.
East and West: the contendersIt can not be denied that the Japaneseindustry, headed by Sony and NHK, hasbeen working on HDTV concepts, suchas MUSE, longer than the European orNorth American industry. Not surpris-ingly, therefore, during the CCIR 1986Plenary Assembly, it was proposed todeclare the so-called 1125/60 systemdeveloped by the NHK group the worldstandard for HDTV. The system is basedon 1125 picture lines and 60 Hz field fre-quency. A wide range of equipment forthis standard was already available atthat time, and an experiment with aJapanese DB satellite transmitting1125/60 HDTV pictures had been suc-cessful. Two important events preventedthe 1125/60 standard from being ac-cepted, however. One was the FCC's re-jection of it on the ground that it wouldcause total incompatibility with existingTV sets; the other was a request from
EEMDecember 1988
European industries and broadcastersfor more time to study and develop anHDTV system of their own. With thepossibility of support from the USbroadcasters in mind, it is not surprisingthat the European, alternative, HDTVsystem was to pay great attention to agradual introduction of HDTV, withcompatibility, at least initially, as thefirst and foremost concern. Clearly, withthe lost VCR battle in mind (Philips2000 vs VHS and BetaMax), theEuropean radio & TV industry was keento avoid another instance of the sheermass of Far Eastern products simplypushing aside a technically superior con-cept.The CCIR was sensitive to all argumentsagainst acceptance there and then of the1125/60 standard, and ruled that interimstudies were to be conducted beforetaking a final decision in 1990.In the two years since 1986, TheEuropean industries, headed by Philips,Thomson and Bosch, and known underthe name Eureka 95 Group, have notonly developed their own HDTV stan-dard, but also managed to give it globalsignificance thanks to the keyword, in-itial compatibility.In the case of the 1125/60 system, allexisting standard NTSC 60 Hz equip-ment would require the addition of acomplex standards converter. This isbasically because 1125 is not a multipleof 525, the number of lines used in astandard NTSC picture. By contrast, theEureka 1250/50 system retains compati-bility because 1250 is simply two times625 lines. An American version ofHDTV meeting the FCC regulationswould probably be based on 1050(2 x 525) lines and 60 Hz.
STUDO
PAL
43 Aspect Ratio
4:3 Aspect Ratio
TRANSMISSION
Extended Definite-,169 Aspect Ratio
MAC Cr.a7-e:Phase :T.
C. AY
HDTV16:9 Aspect Ratio
Wide MAC ChannelPhase F.T.
HO -MAC ChannelPhase BZ
Fig. 2. Interrelation of studio, transmission and display standards (drawing courtesy Indepen-dent Broadcasting Authorio).
Pets,6-teity
P.a., I
Fraee I
Prase If
Prase X
DgcV TV
1.13-4fAC P&p13e1rx:m Teensrn
Centr.n
.55 93 91 92 93 99 95 95
880210 - 14
Fig. 3. Phases in the evolution of the MACtelevision standard, which will take TVviewers into the nineteen -nineties.
A line of new S (super-) VHS equipment from JVC includes a portable camcoder, an editingrecorder, an editing control panel, and a 400 -line, 21 -inch, high -resolution PAL/SECAMmonitor. Photograph courtesy JVC Professional Products Ltd.
In Brighton, The Sony 1125/60 Groupdisplayed the largest ever collection ofHDTV equipment under one roof, in thesports centre of the University of Sussex,a few miles from the centre of Brighton.Demonstrations included an HDTV re-cording of the Genesis concert atWembley in July 1987, displayed on acinema -sized screen and accompaniedwith a digital sound track. A wide rangeof cameras, standards as well as field -rate and PAL/SECAM conversionequipment, was also successfullydemonstrated. To show that 1125/60HDTV pictutes can be carried over con-siderable distances without the need fortransmitters and receivers, the Sonygroup had arranged a live link betweenthe Kingswest Cinema at Brighton, tem-porarily changed into an all -electroniccinema, and the SVC studios in London,covering a distance of about 100 km.
Fig. 4. Logos used by the Eureka -95 group.
18 EE
December 1988
The link was made with the aid of aBritish Telecom fibre optic network,which operated at a data rate in excess of1 Gbit/s, carrying the multiplexedluminance and chrominance compo-nents.The Eureka Group had built a separate
pavilion which housed a HDTV studiowith a number of cameras, wide-screenmonitors, mixing desks, and a completetelecine set-up for conversion of films toHDTV format. Also on display wasBritish Telecom's M3VDS system.Millimetre -wave Multichannel Multi -point Video Distribution Service is analternative to cable networking, andallows the wireless distibution of about20 TV channels in county towns andsuburban areas of large towns. A singleMNDS transmit site would cover about8 krn2. Reception aerials are small,unobtrusive and simple to fit on therooftop or on to a chimney. Frequenciesused for MWDS networks are in the 29and 39 GHz bands.
Eureka 95: philosophy andtask assignmentThe EU 95 HDTV Group, a joint in-itiative of Bosch, Philips, Thomson andThorn EMI, aims at defining a worldstandard for high -definition television inthe 1990s. As already noted, the full pro-posal for such a system is to be presentedat the CCIR plenary assembly of 1990.The European unification proposals for1992, the planned use of high -power DBsatellites and the DMAC and D2MACtransmission standards are importantfactors that have spurred electronics
Fig. 5. FDL60 CCD HDTV -compatible Telecine equipment from BTS allows cinema -formatfilms to be sent to a HDTV studio. Photograph courtesy Broadcast Television Systems GmbH.
manufacturers into getting together in aserious attempt to develop a compatibleHDTV system that does not make exist-ing consumer equipment obsolete over-night. Interestingly, the C -MAC trans-mission standard, used by the EBU, andof particular interest for the Scandina-vian countries, is not mentioned in thecontext of Eureka HDTV.To maximize the power of the group,each participant is assigned a particulartask in a Project Group - see Table 1.
Fig. 6. Radio Televisione Italia has been appointed Project Leader of the Programme MaterialGroup in the Eureka 95 HDTV consortium. The photograph shows the KCH 1000' flexible-standard HDTV camera in use by a RAI camera crew. Photograph courtesy Broadcast Tele-vision Systems GmbH.
The total workload of the workgroups isdefined by discipline rather than bysystems or components, and comprisessystem studies, development of pro-totypes, and definition of key compo-nents.Clearly with the potential of the NorthAmerican market in mind, the EU 95HDTV group will also study the possi-bility of standards conversion to andfrom 1050 lines/60 Hz.
More interesting noveltiesETEL (European Television EncryptionLimited) is a new company, jointlyowned by General Instrument Corpor-ation (GIC) and British Satellite Broad-casting Limited (BSB). At IBC88, ETELpresented the basic outlines of theEurocypher System, which is of par-ticular interest for the BSB direct -broadcast project. As shown in Fig. 7,Eurocypher comprises a system of com-puters and software, encryption hard-ware and modules built in, or attachedto, the consumers' satellite receivers. TheEurocypher system has been derivedfrom GIC's VideoCipher system, whichis the de facto market standard forsatellite -TV encryption in the USA.ETEL is also co-ordinating work on yetanother conditonal access system,Eurocrypt, which is said to be a com-pletely new concept.
The BBC Engineering Departmentshowed some interesting newdevelopments at IBC88, and staffmembers delivered papers on these dur-ing the Programme of Technical Ses-sions.
Table 1.
EE 112December 1988
Eureka 95 HDTV: Project groups
Working group Project leader Keywords in task description1. Fundamentals of CCETT Picture quality assessment.picture and sound Colorimetry. Test pictures.
2. Production Thomson Studio standards conversion.standards and MAC to PAL, MAC to SECAMstandards conversion conversion
3. Studio Equipment Bosch 50 Hz HDTV equipment.Camera technology
4. Transmission IBA Satellite broadcasting of HD -MAC. Studio, inter -studio anduplink networking.
5. HD -MAC encoding Philips Encoding/decoding hardwaredecoding and software for transmission
& reception of HDTV via aMAC channel.
6. Display standard BBC Definition of dis-and up -conversions play requirements. for 1250 -line
HDTV. Direct -view CRTs andprojection systems.
7. Receivers Ferguson Practical receivers based onresults of studies in WorkingGroups 5 and 6. Developmentof 16:9 aspect ratio CRTs, aMAC chip set, D -A and A -Dconverters.
8. Carriers Philips Modulation techniques forconumer-oriented carriers(media). HDTC VCRs, Videodisc player. Electronic still pic-ture.
9. Programme Material RAI High -quality programmematerial for HDTV demon-strations.
10. Bit -rate Thomson Digital video technology.reduction Interface with RACE Main pro-
gramme. Digital inter -studiolinks.
Active line rotation (ALR) of PALsignals is a scrambling technique thatclosely resembles component rotationused in the MAC system. Figure 8 showsthat active -line video information is cutand rotated so that the portion extendingbeyond the end of the line is transferredto the space at the beginning of the line.The degree of security offered by ALR isrelatively high, because cut -points canbe positioned at many different pointsthroughout the active -line period, andcan be changed on a line -by-line basis.Although ALR is a relatively com-plicated method of scrambling, it re-quires only small storage devices in thedecoder. A purely analogue implementa-
Eureka 95 HDTVParticipants
Belgium:Barco Industries
France:AngenieuxCaptain VideoCCETT (TDF & France Telecom)OceanicSFPThomson S.A.
Finland:Nokia
Federal Germany:Forschungsinstitut der DBP beim FTZFubaGreatz-NokiaGrundig A.G.Heimann GmbHHeinrich -Hertz InstitutIntermetallRobert Bosch GmbHSchneiderTechnische Universitat BraunschweigUniversitat Dortmund
Italy:RAISeleco
Holland:NV Philips Gloeilampenfabrieken
Sweden:Swedish Telecom Radio
Switzerland:Kudelski
United Kingdom:BBCBritish TelecomIBAITV AssociationQuantelRank CintelFerguson
The Eureka 95 HDTV Directorate is formedby:Robert Bosch GmbH, Philips International BVand Thomson Consumer Electronics.
Fig. 7. ETEL (European Television Encryption Ltd.) will develop and co-ordinate the condi-tional access system to be used for the BSB direct broadcast venture.
20 EE
December 1988
As part of the Eureka HDTV project, Philips have developed an HD -MAC optical video discdrive based on a solid-state laser. The player, which was first demonstrated during IBC88, iscapable of delivering stable HDTV pictures (1250/50/2:1) as well as normal TV pictures(635/50/2:1) in the new 16:9 wide screen picture format. Interestingly, the prototype shownat IBC88 had a MAC decoder circuit based on Intermetall's chip set. Advance information;photograph courtesy Philips.
Lion of ALR could be based on CCDdevices. Experimental ALR scrambledsignals have been broadcast from theBBC -2 transmitter at Crystal Palace on anumber of occasions since initial tests inAugust 1986. The demonstration ofALR equipment on the IBC stand of theBBC gave convincing results: an ab-solutely unintelligible picture in theabsence of the descrambler!
The BBC also showed their progress inthe development of a Radio Data System(RDS), whose operation and generalbackground was covered by two papersdelivered during the Technical Sessionsat IBC88. RDS is basically a radio pag-ing system that aids VHF broadcastlisteners in vehicles in staying tuned to aparticular programme, e.g. Radio 4, ir-respective of their actual position. RDS
Fig. 8. Active line rotation is a new methodof TV -picture scrambling developed by theBBC Engineering Department.
also offers interesting possibilities forselective transmission of traffic infor-mation and emergency CABS via localVHF transmitters. A local radio station(for example, Radio Kent) which is aboutto make a travel announcement signalsthis intention to the central RDS com-puter via an existing data network thatlinks studio centres. The RDS computerthen determines which local transmittersin the area of interest are to transmit theRDS information. RDS-compatible carradios so programmed will then switchfrom, say, the Radio 2 programme, tothe local radio station, and convey thetravel news to the driver.The RDS system has been developed incollaboration with other Europeanbroadcasters, and uses a subcarrier at57 kHz in the baseband spectrum shownin Fig. 9.
H
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880210 - 17
Fig. 9. Baseband spectrum of the stereo multiplex signal with the new RDS (radio data sys-tem) service that will aid listeners with suitably equipped FM receivers to find the station oftheir choice more easily. RDS was sucessfully demonstrated on the BBC stand during IBC88.
Ikegami series -15 colour monitor with a digital control system plus auto set-up probe for auto-matic setting of brightness, chroma and contrast to a referenced level. Photograph courtesyIkegami Electronics U.K.
EE
December 1988
PITCH CONTROL FORCD PLAYERS
In general, only professional compact -disc players are providedwith a pitch control. Domestic types so equipped are few and far
between, and are also pretty expensive. A circuit is describedhere that makes it possible for a pitch control to be added tomost CD players at a fraction of the cost of a professional unit.
Correct operation of a CD player is en-sured by a central, crystal -controlledclock operating at 11.2896 MHz. In theblock diagram of a typical CD player-see Fig. 1-this clock is contained in thedigital filter chip (SAA7220), but thecrystal is external to this IC. The clockcontrols not only the data processing,such as decoding, error correction, anddigital -to -analogue conversion, but alsothe drive motors.In CD players less sophisticated than thePhilips CD960 (used for Fig. 1), a digitalfilter is not used and the crystal is con-
nected to the XTAL inputs of thedecoder chip (here a Type SA7210).For the present purposes, it is fortunatethat all the circuits of a CD player con-tinue to operate correctly if the clock fre-quency is altered, although the motorswill run faster or slower, depending onwhether the frequency is increased or re-duced. In principle, therefore, it is fairlysimple to alter the speed of the disc drivemotor, and thus the pitch of the soundoutput.According to most manufacturers, theclock frequency should be within ±-100,7o
of the nominal value, but trials in anumber of CD players have shown thatmuch greater tolerances are permissible.At very large deviations, however, somespecial functions, such as skip andsearch, fail to operate correctly. In theproposed circuit, the clock frequencymay be varied between 9 MHz and13 MHz without any detrimental effectson the electronic circuits in the player.Basically, all that is required is to remove(unsolder) the crystal from the appro-priate printed -circuit board in the CDplayer and replace it by the coaxial cable
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EE
December 1988
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from the proposed pitch control. The os-cillator circuit of a typical CD player isshown in Fig. 2. It should be noted thatreplacement of the crystal invalidates theinitial manufacturer's warranty.
PLL synthesizerIn professional CD players fitted 5 withpitch control, the variable clock fre-quency is derived from a simple, free -running voltage -controlled oscillator-VCO-in which the voltage is variedwith the aid of a potentiometer, asshown in Fig. 3. When the VCO is in cir-cuit, the frequency, and thus the speedof the disc drive motor, may be alteredby turning or sliding the potentiometer.Note that this circuit is provided with aswitch that allows instantaneous return
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880165 -16
Fig. 3. Many professional CD players use this simple
to the original crystal frequency when re-quired.This type of circuit has some drawbacks,however: owing to temperature drift, theVCO is not very stable; and the speedvariation can not be controlled accurate-ly because of the lack of an indicator.The proposed circuit, therefore, has beenenlarged and enhanced as may be seenfrom its block diagram in Fig. 4 and itscircuit diagram in Fig. 5.The circuit is based on a phase -locked -loop (PLL) synthesizer. The reference
circuit to obtain pitch control.
oscillator of the synthesizer is driven bythe crystal removed from the CD player.The frequency of the VCO is comparedconstantly with that of the reference os-cillator and made to keep in step with it.This is effected by dividing the referencesignal by 400 and the VCO signal by afactor of between 320 and 460. Any devi:ation of the VCO frequency results in anappropriate correction in the phase com-parator. A LED lights when the PLL isnot locked. With the PLL locked, oper-ation of the CD 'player is just as accurate
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24 EE
December 1988and stable as before the crystal was re-moved from its original position.Even when the PLL is not locked, how-ever (indicated by a LED lighting),nothing detrimental happens: the VCOthen operates in a free -running mode.The programmable divider in the feed-back loop of the VCO is set with the aidof miniature pushbutton switches thatcontrol an 8 -bit up -down counter. Theoutput data of the counter may vary thedivide factor of counter IC9 between160 and 230.The up -down counter is also connectedto EPROM IC6. This circuit is used as adecoder driving a three -digit display.The binary output of the up -down coun-ter is converted into 0.5% steps on thedisplay: 11001000 represents 00.0%.Starting from a counter output of11001000 (decimal 200), each change of1 bit (more or less) causes a display shiftof 0.5070.The EPROM also limits the frequencyshift to -20% and +15%, because bit 6(D5) at its output is fed back to blockthe up -down counter.The EPROM also provides polarity indi-cation: when the up -down counter out-put decreases, diode Di lights to showthe minus sign.Since the EPROM content is dividedinto three, a Type 4017 IC is used formultiplexing the three display segments.Apart from main dividers IC9 and ICio,there are two bistables in ICn that serveas binary scaler. These dividers ensurethat the phase comparator is providedwith true square -wave pulses to preventany problems in the phase comparison.The circuit of ICI2 is shown in Fig. 6.The time constant of network R2.7 -R20-
CH at pin 13 determines the regulating
Fig. 6. Internal circuit of phase comparatorchip Type 4046.
time of the PLL. The regulating voltageis applied to double variable -capacitancediode D3 in the VCO circuit.The frequency of the VCO is determinedby L1 -C12 -C13 -D3. The oscillator isbasically the same as the original crystaloscillator.
The oscillator signal is fed via inverterN12 to the output terminal and also todivider IC9. The potential divider at theoutput, R3 -R33, provides level matchingand forms a low-pass filter with thecapacitance of the coaxial cable and thecapacitor at the XIN terminal of theSAA7220 in the CD player. Both thesemeasures ensure that the signal at pin Ilof the SAA7220 is a true sine wave at alevel of about 1 Vpp.
Practical considerationsA phase -locked loop synthesizer onCMOS ICs and operating over the range9-13 MHz can be constructed properlyonly on the carefully designed PCB
shown in Fig. 7. It is essential that thesupply lines are decoupled properly as,for instance, those to the VCO by RHand C24.Since the pitch control circuit draws upto 220 mA, it will normally not be poss-ible to take the power supply from theCD player. A simple +5 V supply willdo, however.Note that because of the high fre-quencies the dividers in the PLL shouldbe HC or HCT CMOS types; all otherICs may be standard CMOS.The simple content of the EPROM isgiven in Fig. 9 to enable constructors toprogram this device themselves.Coil Li consists of 16 turns enamelledcopper wire of 0.2 mm diameter on aNeosid Type 7F1S former. The ends ofthe winding are soldered to two of thefive pins on the base of the former,which themselves are soldered to thePCB.The inductor is trimmed with the aid ofa non -conducting trimming tool. Thecore is situated correctly if UNLOCKdiode D2 does not light at the extremesof the frequency range (+15% and- 20%).It is best, however, to trim the inductorwith the aid of a frequency counter. It isthen possible to make the readings onthe 3 -digit display (in 070) and on thecounter (in MHz) equal. If the PLL isnot locked properly, the reading on thecounter becomes unstable and D2 willlight.With Li trimmed correctly, theregulating voltage at pin 13 of the phasecomparator must be about 0.5 V at+15010 frequency shift, and around4.0 V at -20%.It is also possible, if a frequency counter
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Fig. 7. Printed -circuit board for the pitch control unit.
EE 121December 1988
is not available, to measure the voltageacross D2. Since that is a pulse -widthmodulated signal, however, an in-tegrating multimeter must be used, set tothe DC range. At both extremes of thefrequency shift, the d.c. voltage acrossD2 must be not greater than 150 mV.If the varicap diode, Ds, is out of toler-ance, so that the correct frequency shiftcan not be obtained, the values of Csand C6 may be changed slightly (smallervalue = higher VCO frequency). In ex-treme cases, it may be necessary to in-crease the number of turns on Lt to 18or even 19.
Parts list
Resistors (±6%):R1;R4;1312...Ria incl.=1K0R2;Rs;F123;R3o= 100KR3;136;1'124= 'IMO
R7;R25=10KRe=1K5R9;R33=270RRio=4K7R11=100RRi5=12KR16=18ORR17...R23 incl.=10ORR26=47ORR27=8K2R28= 560RR31=18KR32=680R
Capacitors:CI . ..C2=100nCs;C9=33pCio;Cie=47nCii;C22=4714 10 VC12;Ci3=120pC1a:C15=10nC18;CA;C21;C28=100nC20=100n ceramicC23;C24=47p; 16 V; tantalumC25=2200; 10 V
Semiconductors:D1;02= LEDD3=11132127IC1;IC2=4093IC3=74HCU041C4:1Ce=4029IC6=2764IC7=4017IC8=4511ICs;ICio=74HC40103IC11=4013IC12=4046LDI ...LD3 incl.=7760 common -anode LED
displayTi ...T4 incl.=BC5478T6=BC55713
Miscellaneous:Li = Neosid inductor assembly Type MS+.Si .. .S3 incl.= Digitast switch IITW or
IIT/Schadow).Xi = quartz crystal 11.2896 MHz.PCB Type 880165 (see Readers Services page).
Fig. 8. The completed pitch control board.
0000: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF0010: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF 100020: 35 30 35 30 35 30 35 30 35 30 35 30 35 30 35 300030: 35 30 35 30 35 30 35 30 35 30 35 30 35 30 35 300040: 35 30 35 30 35 30 35 20 25 20 25 20 25 20 25 200050: 25 20 25 20 25 20 25 20 25 20 25 20 25 20 25 200060: 25 20 25 20 25 20 FF FF FF FF FF FF FF FF FF FF0070: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF0080: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF0090: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF 3000A0: 35 30 35 30 35 30 35 30 35 30 35 30 35 30 35 3000B0: 35 30 35 30 35 30 35 30 35 30 35 30 35 30 35 300000: 35 30 35 30 35 30 35 20 25 20 25 20 25 20 25 20OODO: 25 20 25 20 25 20 25 20 25 20 25 20 25 20 25 2000E0: 25 20 25 20 25 00 FF FF FF FF FF FF FF FF FF FF00FO: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF0100: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF0110: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF 120120: 31 31 31 31 31 31 31 31 31 31 31 31 31 31 31 310130: 31 31 31 31 3F 3F 3F 3F 3F 3F 3F 3F 3F 3F 3F 3F0140: 3F 3F 3F 3F 3F 3F 3F 2F 2F 2F 2F 2F 2F 2F 2F 2F0150: 2F 2F 2F 2F 2F 2F 2F 2F 2F 2F 2F 21 21 21 21 210160: 21 21 21 21 21 21 FF FF FF FF FF FF FF FF FF FF0170: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF0180: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF0190: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF 3201A0: 31 31 31 31 ?1 31 31 31 31 31 31 31 31 31 31 310180: 31 31 31 31 3F 3F 3F 3F 3F 3F 3F 3F 3F 3F 3F 3F01C0: 3F 3F 3F 3F 3F 3F 3F 2F 2F 2F 2F 2F 2F 2F 2F 2F01DO: 2F 2F 2F 2F 2F 2F 2F 2F 2F 2F 2F 21 21 21 21 2101E0: 21 21 21 21 21 01 FF FF FF FF FF FF FF FF FF FF01FO: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF0200: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF0210: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF 100220: 39 39 38 38 37 37 36 36 35 35 34 34 33 33 32 320230: 31 31 30 30 39 39 38 38 37 37 36 36 35 35 34 340240: 33 33 32 32 31 31 30 20 20 21 21 22 22 23 23 240250: 24 25 25 26 26 27 27 28 28 29 29 20 20 21 21 220260: 22 23 23 24 24 25 FF FF FF FF FF FF FF FF FF FF0270: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF0280: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF0290: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF 3002A0: 39 39 38 38 37 37 36 36 35 35 34 34 33 33 32 3202B0: 31 31 30 30 39 39 38 38 37 37 36 36 35 35 34 3402C0: 33 33 32 32 31 31 30 20 20 21 21 22 22 23 23 2402D0: 24 25 25 26 26 27 27 28 28 29 29 20 20 21 21 2202E0: 22 23 23 24 24 05 FF FF FF FF FF FF FF FF FF FF02F0: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
880165.17
Available from C -I Electronics P.O. Box22089 6360 AB Nuth The Netherlands. Fig. 9. Content of EPROM 106.
26 EE
December 1988
Fig. 10. Pitch control unit connected to oneof the prototypes, a Philips Type CD960 CDplayer.
It is also possible to alter the frequencyof the oscillators driving the up -downcounter to some extent. With the UP orDOWN key depressed, the reading onthe display increases or decreases insteps. The rate of change of these stepsis determined by time constant Rs -C3 orR6 -Cs. Increasing the value of either theresistor or capacitor makes the readingchange more slowly.If the supply voltage comes on tooslowly, it may be that the value of C6 istoo low for power -on -reset. Either thevalue of the capacitor or that of R7 maybe increased to speed up the operation(R7 may be increased up to 100 k).The PCB in Fig. 7 may be cut into twoto give separate synthesizer and displayboards. It is then, for instance, possibleto fit the display (as in the prototypes)into the CD players behind a small win-dow to make frequent readings possible.It is, of course, also possible to constructthe pitch control unit in a self-containedmetal case and connect this to the CDplayer via as short a length of coaxialcable as possible. The case must be ear-thed to obviate external radiation of the11 MHz clock signal.
Fig. 11. Connection of the coaxial cablefrom the pitch control unit to the relevantboard in the CD960.
NEWSBT'S COMMITMENT TOENTERPRISE AND EDUCATIONBritish Telecom has pledged that it willprovide work experience for more than1,000 schoolchildren during the comingyear as part of the company's commit-ment to the Department of Trade and In-dustry's "Enterprise and Education" in-itiative.The company has co-operated in pro-viding work experience for pupils over anumber of years as part of its educationservice activities that provide curriculummaterials, in-service training and teacherfellowships.
FUTURE SUBMARINECOMMUNICATIONS SYSTEMSA consortium of GEC -Marconi, BritishAerospace, and STC has been awarded acontract by the British Ministry ofDefence to carry out a feasibility studyto investigate and define the communi-cations needs of the Royal Navy's nextgeneration of nuclear -powered sub-marines.
NEW ADDRESS FOR GB2ATGBob Andrews, G1JZJ, who runsGB2ATG, one of the few amateur radionews broadcast services in the UK, has
moved to 52, Linridge Road, Erdington,Birmingham B23 7HX.GB2ATG is transmitted on the first andthird Sunday of each month on3.590 MHz, 14.090 MHz and144.600 MHz.Amateurs are invited to join the group ofvolunteers that transmit GB2ATG.
AUTOMATED SEMICONDUCTORASSEMBLY EQUIPMENT MARKETIN EUROPEAutomated Semiconductor AssemblyEquipment Market in Europe, a reportfrom Frost & Sullivan, says that Europeis becoming the world's fastest -growingmarket for semiconductor assembly.Chief among the factors underlying thisgrowth in the face of traditionalJapanese and American industrydominance is the rise of ASICs(application -specific integrated circuits).
AUTOMATED SEMICONDUCTOR ASSEMBLYEQUIPMENT MARKET IN EUROPE - 1988
W. Germany S19.11/I
U.K 51^5 EA4
SIVAScorieara $2.714
Rau d W. Erope 57.3.lFrance SI5 al
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EURO SATELLITECOMMUNICATIONS NETWORKCOMPLETEDThe last of the five European communi-cations satellites (ECS) ordered ten yearsago has just been formally accepted bythe Eutelsat Organization following itslaunch in July and subsequent position-ing in space.The European Space Agency (ESA)ordered the five ECS satellites fromBritish Aerospace as a follow-on fromthe successful BAe-built OTS satellite,which pioneered the use of satellite com-munications in Europe and last Maybegan its 11th year in orbit.
$56 MILLION CONTRACT FORMARCONI/CINCINNATIIn the largest award of this kind evermade by the United States InformationAgency for any domestic or inter-national project, a joint venture of Mar-coni Electronics Inc. and CincinnatiElectronics Corporation has received acontract for almost $57 million tomodernize the Voice of America (VOA).The VOA was instructed by a NationalSecurity Council directive to develop astronger, more reliable signal, particu-larly to those areas of the world whereinformation does not circulate freely.
EE
December 1988
COMPUTE RDAMED TESTEQUIPMENT
by AW Moore MA
The (relatively) low cost, ease of use and flexibility of the personalcomputer make it eminently suitable for the control of test andmeasuring instruments. Many instrument and computer makers
have realized this and have brought on to the market a numberof parallel and serial buses to link a personal computer to one or
more suitable instruments.
Not all that long ago, electronic equip-ment could be tested by the measuring ofa few parameters (voltage, frequency,and so on) at some selected points in thecircuit. Nowadays, much of such equip-ment is controlled by a microprocessor.Testing of this kind of equipment canonly be carried out effectively bymeasuring the relevant parameters atmany points in the circuit. Moreover, anumber of these measurements needs tobe taken simultaneously, owing to theirinterrelation.With electronic equipment becomingmore complex, instruments for testingsuch equipment have become more com-plex also and many are now controlledby a microprocessor. Such instrumentsare called automatic test instruments. Ifthe internal microprocessor is controlledby an external computer, we speak ofcomputer -aided test equipment.Computer -aided test equipment may bededicated, i.e., specifically designed andmade for the relevant purpose, or it mayconsist of a PC controlling general-purpose instruments as shown in Fig. 2.A number of internationally well-knownmanufacturers, such as Philips, Hewlett-Packard, Tektronix, Schlumberger andSiemens have marketed dedicatedcomputer -aided test equipment, butthese are beyond the scope of this article.If several instruments are to be con-trolled by a single PC, as in Fig. 2., it isan obvious advantage if a common busis used. Such a bus makes the set-up veryflexible since it allows extra instrumentsto be added without much trouble.Buses used to link the various items in atest set-up should be of a standarddesign to enable instruments supplied bydifferent manufacturers to interface. Anumber of standards has come about asa result of co-operation between various
Fig. 1. 1-)pical computer -cum -instruments set-up.
manufacturers, and some of them havebeen accepted by standards organizat-ions, such as the IEEE and IEC.There are parallel and serial buses, aswell as Local Area Networks (LANs).Some buses are used for intra-board con-nection, such as the STD (IEEE961) bus,the VME (Versatile Module Europe) bus,and the Futurebus (IEEE896), whereasothers are used for interconnecting in-struments. Of the latter, the best knownis the IEEE488. The IEC625 bus incor-porates the IEEE488 standard, but usesa different connector. Local Area Net-works are used to connect a variety ofdifferent terminals together over a givenarea.The parallel intra-instrument buses are
fundamentally compatible and areusually called general-purpose interfacebuses (GPIBs). A GPIB allows up to 14instruments and a computer to be con-nected together. The instruments may belisteners (which can only receive data) ortalkers (which can only send data).Many instruments manufacturednowadays are provided with a GPIB in-terface and switches that are used to setthe bus address.Sixteen active lines are used to imple-ment the GPIB, and these are dividedinto three groups as shown in Table 1.The eight data lines are bidirectional anddata is transferred byte by byte.The control bus consists of five lines.When the ATN (attention)line is ac-
28 EE
December 1988
tuated (by the PC), it signifies to all in-struments on the bus that they must giveup use of the bus and interpret the databus as commands. The IFC (interfaceclear) line is asserted by the PC and usedto initialize the instruments. The REN(remote enable) line is used by the PC toinstruct the instruments to be ready forremote control. The SRQ (service re-quest) line is used by an instrument tointerrupt the controller to signal that itrequires attention. The EOI (end oridentify) line is used to indicate the endof a multiple -byte transfer or, with ATN,to force the PC to execute a polling se-quence.The transfer control lines control thetransfer of data on the data bus. TheDAV (data valid) line is set by a talker toindicate that valid data are present onthe data lines. The NDAC (not data ac-cepted) line is set by a listener during
Table 1
Data busPin Function
1 Data line2 112
34 D4
13 Ds
14 DE
15 D?16 Da
Control bus 5 Control line E019 IFC
10 SRQ11 ATN12 Screen17 Control line REN
Transfer bus 6 Transfer line DAV7 NRFD8 NDAC
18192021222324 Logic ground
Iground
reading the data. The NRFD (not readyfor data) is set by a listener to indicatethat not all listeners are ready to acceptdata.The IEEE488 standard does not definethe syntax or code of messages on thebus.
Some typical availableequipmentThe Intepro Micro Series power supplytest equipment from Limerick -based In-tepro Systems is a PC expanded with abus extender card that is complete withmemory and capable of linking up to255 plug-in instrument modules.Modules currently available includeDVM, scanner, power relay, and ripple -and -noise measurement boards.
Fig. 2. Typical GPIB structure.
A full range of plug-in data acquisitionand controls cards for IBM PCs andcompatibles is available from Bleu ChipTechnology.Digital interface cards include the PIO-48 that has 48 programmable input oroutput lines. Other digital cards have op-tocouplers, Darlington drivers, relaysand counter/timers.The AIP-24, one of the analogue range,has 24 channels, 12 -bit analogue -to -digital converter, sample -and -hold, anda programmable gain amplifier.Other cards include multi -function cardswith analogue and digital channels, ther-mocouple inputs and communicationscards with RS232, RS422, RS485, and20 mA standards.
ANALYSER software from NumberOne Systems is claimed to have becomethe largest selling Circuit Analysis soft-ware package in Britain with versions for
the BBC and IBM (and compatible)PCs.By simulating accurately the AC per-formance of a circuit design, it can givethe designer confidence that circuits willbehave as required, without his needingto resort to expensive test and measuringequipment while "fine tuning" a design.At higher frequencies, unanticipated ef-fects caused by interelectrodecapacitances and so on are immediatelymade clear.ANALYSER performs an AC FrequencyResponse analysis on circuits enteredinto the software, and presents results intabulated and graphical form. Analysisof gain, phase, group delay, input im-pedance, and output impedance versusfrequency are made to give the electroniccircuit designer a powerful tool withwhich to assess the performance ofdesigns. Particularly useful is the abilityto change one or more componentvalues and recalculate to see what the ef-fects of such changes are. This allowsrapid solutions to design problems, andminimizes the need for breadboardingand the resultant waste of componentsand, more important, time.Strays and parasitics at higher fre-quencies may also be taken into account.ANALYSER allows resistors, capacitors,inductors, transformers, field-effect andbipolar transistors, operational ampli-fiers, transmission lines and microwavestriplines to be included as circuitelements. Circuits up to 60 nodes and180 components may be analysed, andthere are libraries of active componentsavailable that hold the pre -enteredspecifications of up to 26 of each type(bipolar transistor, FET, opamp). Datamay be changed by the user to suit thetypes most commonly worked with.
Fig. 3. PSION organizer radically changes RS -232 control & storage potential of IFR test in-struments.
EE
December 198829
Although not strictly a "computer -aided" test equipment, Fieldtech'sORGANIZER II and COMMS LINKare of interest to note.The ORGANIZER II takes the place ofa PC as controller to drive IFR test in-struments. Since the unit is little biggerthan multi -function calculator, it may beused as hand-held controller that can bestored in the test -set lid when not in use.
Some useful addresses.
Amplicon Electronics LtdRichmond RoadBRIGHTON BN2 3RLTelephone (0273) 608331
Blue Chip TechnologyMain AvenueHawarden Industrial ParkDEESIDEClwyd CH5 3PPTelephone (0244) 520222
Fieldtech Heathrow LtdHuntavia House420 Bath RoadLONGFORD UB7 OLLTelephone 01-897 6446
Fluke LtdColonial WayWATFORD WD2 4TTTelephone (0923) 40511
Hewlett-Packard Ltd -
Nine Mile RideWOKINGHAM RHII 3LLTelephone (0334) 773100
Intepro Systems LtdCrescent House77-79 Christchurch RoadRINGWOOD BH24 1DHTelephone (0425) 471421
Keithley Instruments Ltd1 Bonbon RoadREADING RG2 ONLTelephone (0734) 861287
Number One Systems LtdHarding WaySomersham Road
St. IvesHUNTINGDON PE17 4WRTelephone (0480) 61778
Philips InstrumentsMullard HouseTorrington PlaceLONDON WCIE 7HDTelephone 01-580 6633
Schiumberger InstrumentsVictoria RoadFARNBOROUGH GUI4 7PWTelephone (0252) 544433
Siemens LtdSiemens HouseWindmill RoadSUNBURY-ON:THAMES TW16 7HSTelephone (09327) 85691
Tektronix LtdFourth AvenueGlobe ParkMARLOW SL7 IYDTelephone (06284) 6000
NEWSNEW COMMUNICATIONSPACKAGE FOR INFANTSA new educational package for infantclasses has been produced by BritishTelecom's Education Service. EntitledAir, Land and Sea Communications, it isdesigned to help teachers explore thesubject of communications with 5-7 yearold pupils.Using simple language and colourful il-lustrations, the resource contains awealth of factual information coveringthe history of the telephone from Alex-ander Graham Bell to the modernpayphone, undersea cables and satellites.
GEC NATIONAL ONEAPPROVES SUBSCRIBER RADIOSNational One, the public trunked mobileradio network run by GEC -Marconi, hasgiven certificates of conformance to TaitMobile Radio Ltd (T540TR), MarconiMobile Radio (RC630) and Motorola(MC Micro), thereby approving eachcompany's equipment for registration onthe National One system.
INMARSAT IN CHINAINMARSAT Director of Adminis-tration, Noel Isotta, and CLTC Directorof Tracking, Telemetry and Command,Zong Wenxuan, recently signed a con-tract under which CLTC (China SatelliteLaunch Tracking and Control) will pro-vide a range of services for theINMARSAT-2 Pacific Ocean Region sat-
ellite. Under the terms of the contract,CLTC, a division of China's Commis-sion on Science, Technology, and In-dustry for National Defence, will pro-vide a 24 -hour dedicated tracking stationin Beijing. Because of its location, thisearth station will be able to cover bothINMARSAT's Pacific Ocean and IndianOcean Region satellites.
ELECTRICAL SKILLS FROMNORWAYA comprehensive survey of electrical andelectronics expertise offered to inter-national markets by Norwegianspecialists in this field is provided byNorway Exports - Electrical Tech-nology, a publication from the ExportCouncil of Norway. Apart from equip-ment and systems for power generation,transmission and distribution, thebooklet coveres installation equipment,appliances and electronic products.Amply illustrated throughout in fullcolour, the publication concludes with asection that lists 24 companies that playa leading role in Norway's electrical -electronics industry. It is available free of
charge fromNorwegian Trade Centre 20 Pall Mall LON-DON SWIY SNE.
HTEC PUTS THE IBM PC/AT ONTHE VMEBUSA new 80286 -based module from HTECis designed to combine to advantages ofVMEbus power, form factor and per-formance with the broad software sup-port of the IBM PC/AT. The HVME-AT286 functions as a stand-alone com-puter, as a single CPU system controllerin a VMEbus system, or as one of severalCPU elements in a multiprocessor con-figuration.
DBS MARKET IN THE USAAccording to Frost & Sullivan ReportThe Home TYRO/DBS Market in theUS 1988-1993, the pattern in the DirectBroadcast Satellite market will follow asimilar course as broadcast TV, cableTV, and VCRs. Acceptance is slow atfirst while people get used to the idea.Then popularity soars for a number ofyears. Finally, demand levels off as themarket reaches saturation.
HOME PIR13.13BS MARKET IN THE U.S.5:25,-,77Cra Fieek,VE5114.11.13
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30 EE
D rtlbe 988
AUTONOMOUS INPUT/OUTPUTCONTROLLER
A user -configurable I/O controller that gives digital and analogueinterfacing power to your computer's RS232 outlet. Fast, simple tobuild and program, and intelligent enough to deal with up to 64digital and 12 analogue channels, this microcontroller-driven I/O
distribution box should prove invaluable in many applicationswhere a computer runs a small or large-scale automated control
job, be it industrial or domestic.
The autonomous I/O controller de-scribed here is basically a versatile, in-telligent, computer peripheral that canbe connected in the bus structure pro-posed for the microcontroller-drivenpower supply published earlier this year(Ref. 1). Like the power supply, the I/Ocontroller derives its intelligence from aType 8751 microcontroller from Intel.The control program that resides in thischip has been written exclusively for thisproject in the Elektor Electronics designdepartment.Applications of the I/O box arise almostautomatically when a computer is tocommunicate with the outside world.These applications range from essen-tially simple, such as the control of LEDmatrices, relays or electronic switches, tomore sophisticated, interactive, ones in-cluding the control of motors, but alsoalarm, heating and air conditioningsystems. The list of applications can beextended even further with PC -controlled battery chargers, light showsand audio distribution equipment. The8 -channel ADC in the system allowsanalogue values provided by a wide var-iety of sensors to be captured, stored andprocessed by the computer.
Part 1
One button - seventy-sixI/O linesThe basic operation of the autonomousI/O controller is best understood afterlooking at the front panel first (Fig. 1)- not a multitude of switches and othercontrols on this, just the on/off switchand a push-button labelled DISABLE our -PUTS with an associated LED. There isno need for any other form of local op-eration, because the unit is controlledentirely by commands sent by the hostcomputer it is connected to. There isnothing to look for at the rear side of theunit either: all that is there is the mainsinput socket and the 9 -way D -socket thatlinks the I/O box to the computer.Part 2 of this article will detail the actualprogramming of the I/O controller withthe aid of a set of commands similar tothose used for the microcontroller-driven power supply. BASIC commandPRINT (or LPRINT) is perfectly ad-equate for sending these commands viathe RS232 port, so that even beginnersneed not worry about bus interfacing,machine language programs, or the in-tricacies of the microprocessor inside thehost computer. Most computers provide
Fig. 1. Front v leW of the autonomous I 0 controller.
some sort of printer output redirectionfacility, so that the use of the RS232 portobviates the need for complex programsto 'talk and listen' to the peripheralsconnected to the I/O box. There is, ofcourse, a price to be paid for all thesebenefits, and this is mainly the limitedspeed of the system. None the less,9600 baud should be fast enough for anyof the applications mentioned earlier,since the minimum pulse duration thatcan be programmed on a digital outputline is about 6 ms.
Three printed circuit boardsFigure 2 shows that the autonomous I/Ocontroller can be expanded to user re-quirements. The system is in principlecomposed of 3 types of sub -unit:
controller board - this holds themicrocontroller, power supply andthe 10 -bit analogue -to -digital con-verter (ADC) with its associated 8 -channel input multiplexer;
bidirectional digital board - this isidentical to that for the 8052AH-BASIC computer (see Refs. 2 and 3);
analogue output board - this is vir-tually identical to that for the8052AH-BASIC computer (seeRefs. 2 and 3).
There is a slight difference to note be-tween the autonomous I/O controllerand the system discussed in Ref. 3. Thisdifference entails the maximum numberof peripheral boards (digital andanalogue output). In the autonomousI/O controller, there may be 0, 1, 2, 3 or4 boards of each type, povided each isallotted a unique address (this will bereverted to in Part 2). It is not allowed toreplace, for example, two analogue out-put boards with two bidirectional I/Oboards, or the other way around.Push-button DISABLE ours urs provides atoggle function for simultaneouslyswitching on and off all digital outputs.The current state of this function is indi-cated by a LED.
EE 13:1December 1988
A further LED, labelled REMOTE CON-TROL lights when the autonomous I/Ocontroller communicates with the hostcomputer.An interesting and original feature of-fered by the system described here is itsability to interconnect pairs of corre-sponding input and output lines with theaid of software (command '0'). A prac-tical application of this feature is shownin Fig. 5 where a pair of I/O lines is usedwith manual switch control.
On the controller boardAs already noted, the controller boardholds the 'brains' of the system, themicrocontroller Type 8751, and the ADCwith its associated 8 -way input multi-plexer. The circuit diagram is given inFig. 3.Since the basic operation of themicrocontroller, ICI, is briefly coveredin Refs. 1 and 4, the device can betreated as a 'black box' that takes care ofthe serial communication, the control ofperipherals (digital I/O, DACs andADC), the multiplexing of the analogueinputs, and the timing for the I/Olatches. The microcontroller has on -chipRAM and ROM.
Circuit IC2 is a supply monitor chipthat ensures the correct initialization ofthe microcontroller at power -on. It alsoworks as a watchdog, checking thepresence of 1.1 ms long pulses on con-troller output line P2.0. When thesepulses fail, the microcontroller is im-mediately reset. This is done to preventthe system generating uncontrolledsignals when the supply voltage dropsbelow the level needed for correct oper-ation, or when the system 'hangs up' dueto some internal malfunction. CPU portline P2.0 is also fed to the bidirectionaldigital boards. Conflicts with the watch-dog are avoided by themicrocontrollerensuring that WR is never activatedwhen a pulse is sent to the watchog chip.Diodes Di and D2 determine the ad-dress, or identification code, assigned tothe autonomous I/O controller - seeTable 1. With 2 diodes, a choice of 4 ad-dresses is available. This will do for mostapplications, given the large number oflines provided by a single autonomousI/O controller.Analogue -to -digital converter (ADC)IC6 is a 10 -bit, 8 -bit databus compat-ible, type from National Semiconductor.The recommended supply voltage forthis chip is 5 V. For optimum conversion
Technical features:
INPUT/OUTPUT MODULES: Modular structure. Largest system configuration supports:
32 digital outputs;32 digital inputs;4 analogue outputs;8 analogue inputs.
Digital interface card has 8 buffered outputs and 8 protected inputs.Up to 4 of these modules can be bused in I/O system.
Analogue output card has 1 output with 10 -bit resolution. Outputvoltage span: 0 to +10.23 V, programmable in 10 mV steps. Up to 4 ofthese modules can be used in the I/O system.
Analogue -to -digital converter on controller board has 8 multiplexed in-puts. Input voltage span: 0 to +10.23 V. Resolution: 10 mV/LSB.
Medium -power open -collector digital outputs are surge -protected, andcan handle 50 V; 500 mA loads direct.
Optional internal connection of digital inputs and outputs. Ideal for multitasking of peripherals on a single serial computer chan-
nel.
PROGRAMMING AND SERIAL INTERFACE: Standard serial interface and data format allow system to be controlled
by almost any microcomputer or terminal. Simple line settings:9600 bits/s; 2 stop bits; no parity bit.
Line settings and selective addressing of peripherals is compatible withmicrocontroller-driven power supply. Up to 4 autonomous I/O con-trollers can be individually addressed via a single serial channel.
Communication with or without echo. Status control codes provided for host computer. All functions are programmable via serial interface. Programmed output voltages are read on analogue outputs; real out-
put voltages on analogue inputs. Digital output lines are individually programmable, or in blocks of
8 bits. Analogue output voltages are individually programmable. Automatic syntax -checker for control commands.
Table 1.
Di D2 listen quit
o o 144 145f o 146 147o f 148 149f f 150 151
o = omitf = fit
accuracy, the reference voltage should beas high as possible, but it must never ex-ceed the supply voltage. The referencevoltage is, therefore, set to +5 V, sup-plied by the well-known precisionstabilizer Type REF -02 (ICs), and thesupply voltage to +5.25 V, supplied byan LM317 (IC9). The voltage differenceof 0.25 V is a safety margin that shouldprevent fluctuations on the outputvoltage of the LIvI317 damaging theADC.The +5 V, -5 V and -12 V power sup-plies on the controller board are of con-ventional design and merit no furtherdiscussion.The operation of the serial interface willbe discussed in Part 2, as part of thesoftware command descriptions.
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EE
December 1988
Analogue -to -digital conversionThe 8 analogue inputs on connector K1are connected to protective diode -resistor networks. The CPU, ICi, con-trols the ADC direct, and the inputmultiplexer, IC3, via 4 level converters,T2 to T5. The INH (inhibit) input of theType 4051 CMOS analogue multiplexer,in combination with capacitor C4 andopamp IC4, makes it possible to realizea basic sample -and -hold function. C4 isdimensioned such that it provides an ac-ceptable compromise between rise andfall time - the conversion error it in-troduces is less that 1/2LSB. Potentialdivider Rio -Pi -R16 scales the sampledanalogue voltage down to a value be-tween 0 and 5 V.The analogue inputs form a high im-pedance when they are not sampled.When they are, the impedance drops toabout 10 k52. The procedure for loadingand conversion to 8 bits of the 10 -bitdata in ADC Type ADC1005 is largelysimilar to that adopted for the TypeDAC1006 (for details, see Ref. 3). Animportant feature of the ADC1005 is itsinsensitivity to current peaks during theactual conversion process, as well as tooccasional negative voltages supplied byopamp IC4. No attempt should be madeto suppress the current peaks by fitting acapacitor at the input of the ADC, sincethis would result in significant conver-sion errors.
Bidirectional digital card andanalogue output cardThe circuit diagrams of these modulesare given in Figs. 4 and 6 respectively.For a description of the operation, referto Ref. 3 (but note the value of R2 onthe analogue voltage board, and thesupply voltages). The address assign-ment can be deduced from Table 2. Thedigital I/O cards can only be addressedby fitting jumpers E0 to E3 (on K3), theanalogue output boards by finingjumpers E4 to E7 (also on K3). Do notswap cards of a different type.
Table 2.
K3 Peripheral module
EO digital card 0El digital card 1E2 digital card 2E3 digital card 3E4 analogue card 0E5 analogue card 1E6 analogue card 2E7 analogue card 3
ConstructionThe printed circuit boards for buildingthe autonomous I/O controller areshown in Figs. 7 (controller board;double -sided, through -plated), 8 (digitalI/O board) and 9 (analogue outputboard). The 26 -way flat -ribbon cable
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DILt4335-2.5
254
6
rmdte.rrn
9
ruitztort
P2 03
BrAl108
1N4148
K2
0
0
O
SV
6cis,93
to 20-1416
0c! 20=
10Cn 00
0
12V
5V
LM336.2_5
401 A
250164 16
S
00
0
Fig. 6. Circuit diagram of the analogue output card.
34 EE
December 1988
Fig. 7. Component mounting plan of the double -sided, through -plated, controller board ofthe autonomous I/O controller.
that 'buses' connectors Ki of the digitaland analogue boards connects these tothe controller board.Construction of the controller boardshould not cause difficulty. Note that allelectrolytic capacitors are radial typesthat are fitted upright. Component R.23is an 8 -way, 9 -pin, single -in -line (SIL) re-sistor network. Make sure that the pro-tective diodes are fitted the right wayaround (Ds to D12: cathode up; D13 toD20: cathode down). The 5 V regulatorsmay be fitted on to the cabinet side panelwith the aid of insulating washers.It is recommended to fit supply decoup-ling capacitor C23 at the track side ofthe board, straight across pins 20 and 40of the microcontroller.The photograph in Fig. 11 shows theprototype of the autonomous I/O con-troller fitted in an enclosure of the samesize as that used for the microcontroller-driven power supply. There is plenty ofspace left for fitting two mains
transformers (a single type that providesapproximately 9 V at 0.8 A, and 15 V at250 mA, may be difficult to obtain).
The drawing of Fig. 10 and the ready-made, self-adhesive, front -panelavailable for this project are used astemplates for preparing the aluminiumfront panel of the enclosure. Rememberto drill recessed holes for the counter-sunk screws that secure the D -typesockets and anything else attached to theinside of the front panel, such ashorizontal support pillars between thisand the rear panel. Small additionalholes are drilled in the front panel asshown in Fig. 10 to give access themultiturn presets on the analogue out-put boards (these holes are not providedin the self-adhesive front panel foil, andmust be punched after carefully liningup the completed analogue' boardsbehind the aluminium front panel). Asharp hobby knife is used for clearing
Parts list
AUTC110MOUS I 0 contraer:Controller board
Resistors (±5%):RI =330KR2;R20;R21=2K2R3. . . R14 incl.:1'117=10KFi1s;Rte=2K21; 1%Ria;Rie=390RR22= I 5ORR23= 10K; 8 -way SIL resistor networkR24=68113; 1%825= 228R2s=221R; 1%827 = 1K0Pr =250R multiturn preset (Bourns series 3266;top adjustment)
Capacitors:CI;Ce;C7;Cs;Ci2;C13;Cis;Cra;Cia;Cia;C21:C22= 100n
Cz;C3=33pC4=1n0Cs=47pC9;C14 = 10p; 16 V; radialGra= 100n ceramicC11=1000;1; 25 V: radialC17;C2a=470p; 40 V; radial
Semiconductors:Br =B80C1500
1;D2;135 D2o incl. = 1N4148D3;04= LED021= zener diode 10 V; 0.4 IN022 .. .D25 incl. = 1N4001Ti =BC55712...T7 incl.=8C5471C1= 8751. Available ready -programmed asorder number ESS704 (see Readers Servicespage; this device is copy -protected).
IC2 = MB3773 (Fujitsu)IC3 =40511C4 = OP -77 (PMI)
[Cs = REF -02 (PM))
ICs=ADC1005 (National Semiconductor)IC7;1Ca=4N25ICa =LM317ICro=7805IC11=7812IC12= 7905
Miscellaneous:Kr = 16 -way angled PCB header with eject
handles.K2= 9 -way male sub -D connector (not on
PCB).
K3= 26 -way angled PCB header with ejecthandles.
Si = miniature push-button.X1= quartz crystal 11.0592 MHz (C -I Elec-tronics).
PCB Type 880184 (see Readers Services page).
the holes for the sub -D connectors in thefoil.
Adjustment of the analogue outputboard is carried out as described inRef. 3. The board with identification
EE 1:1December 1988
Fig. 8. Printed circuit board for the digital I/O board.
Fig. 9. Printed circuit board for the analogue output board.
Paris listAutonomous 1,0 controller:digital 110 board
Resistors:RI ...Re inc1.=100KRe .. .R1 a incl.= 10K
Capacitors:C1=10;r: 161.1C2;C3= 100n
Semiconductors:1Ci = 74HCT377IC2=74HCT5411C3=ULN2803A
Miscellaneous:
Kl= double -row 26 -way right-angled header, or26 -way right-angled male header with ejecthandles.
K2= 25 -way D connector, male. with right-angled pins.
K3= double -row 16 -way straight PCB header.1 jumper for mounting on Ka.PCB Type 880163 (see Readers Services page).
Parts listAutonomous 1,0 controller:analogue output board
Resistors:
Fli=47K5R2=2K2P: =25K or 22K multiturn presetP2 = 10K multiturn preset
Capacitors:Cl=ln0C2;C3= 100n
Semiconductors:D I = LM336-2V5D2;D3 = 1N4148ICI =DAC1006 (National Semiconductor)1C2=0P-77 (PMI)
Miscellaneous:
Kt = double -row 26 -way right-angled header, or26 -way right-angled male header with ejecthandles.
K2= 9 -way D connector, male, with right-angled pins.
K3= double -row 16 -way straight PCB header.1 jumper for mounting on Ka.PCB Type 880162 (see Readers Services page!.
Fig. 10. Front panel drilling template.
36 EE
December 1988
number n is programmed to provide10.00 V with the aid of instruction
Un ,10.00.
The ADC on the controller board is cali-brated by applying a precision voltage of10.00 V and adjusting Pt until the hostcomputer reads exactly this value.Details on programming theautonomous I/O controller will be givenin next month's final instalment.Finally, note that the logic ground andthe analogue ground are interconnectedat one point only, close to the ADC1005.
References:
1. Microcontroller-driven power supply.Elektor Electronics May 1988, June1988, September 1988.
2. BASIC computer. Elektor ElectronicsNovember 1987.
3. Peripheral modules for BASIC com-puter. Elektor Electronics October1988.
4. Single -chip microcontrollers. ElektorElectronics September 1987. Fig. 11. Internal r ior of the prototype.
NEWS
SERT AND IEEIE PLAN MERGERFollowing discussions between theSociety of Electronic and Radio Techni-cians (SERT) and the Institution of Elec-trical and Electronics IncorporatedEngineers (IEEIE), a Report of the JointAmalgamation Committee has beenprepared and the councils of the twobodies are holding meetings with theirmembers to discuss a merger.Copies of the report have been sent to allmembers of SERT and IEEIE, and eachbody is arranging a series of meetingsaround the country so that its memberscan attend and raise questions on anypoints arising from the report.
AFDEC STATISTICS REVEALRECORD BILLINGS FOR JUNEThe latest AFDEC (Association of Fran-chised Distributors of Electronic Com-ponents) figures, covering the electronicdistribution sector for the 2nd quarter of1988, show that billings for June werethe highest in AFDEC's history.Against this, the book:bill ratio hasfallen to a low for the year, which iscaused by the very high sales figuresrather than a poor order intake.The next six months are not expected tobe as good either in absolute terms or interms of relative buoyancy.
RACAL RADIOS SHARE INEVEREST SUCCESSLightweight radio equipment suppliedby Racal-Tacticom provided a vital com-munications link that helped a Britishexpedition on Mount Everest to over-come one of the last great challenges inmountaineering.The two members of the team whobecame the first men ever to traverse suc-cessfully the treacherous pinnacles of thenorth-east ridge of Everest carried twoof Racal's small hand -portable radios tokeep in direct contact with the basecamp some 3660 metres below, despitebad weather, hostile both to men andelectronics.The radios carried by the climbers werePRM4720s, compact VHF transceiversoperating in the 30-88 MHz band. Atthe advance camp, a 50 W HF manpackradio Type BCC39 provided a link witha similar set at the base camp. In ad-dition to this, the base camp was alsoequipped with a UK/PRC351transceiver, which is part of theClansman family of radios used by theBritish Army.
LONG-TERMCOMMUNICATIONS JOINTVENTUREA joint venture agreement worth anestimated £120 million has been signedin Peking by GEC -Plessey Telecommuni-
cations-GPT.The 15 -year agreement includes themanufacture, sales and distribution ofthe company's ISDX (integrated servicesdigital exchange) business communi-cations system. It will involve a phasedtransfer of technology from the UnitedKingdom to Shanghai, where pro-duction will reach 100,000 lines per year.The ISDX was launched in 1983 andquickly became the leading product inthe liberalized UK market. Nearly 1.5million lines of ISDX have been soldworld-wide.
UK SECTION OF FIRSTTRANSATLANTIC OPTIC CABLECOMPLETEDThe British Telecom cable ship CS Alerthas successfully completed laying the500 km long UK section of TAT -8, theworld's first transatlantic optical fibrecable.The UK section of the cable runs fromWidemouth Bay in Cornwall to a specialjunction device on the floor of theAtlantic Ocean. This device will link it toa similar section from France, afterwhich both sections will be connected tothe main 6,000 km span of the cable tothe US.When TAT -8 comes into operation dur-ing 1989, it will carry the equivalent of40,000 simultaneous transatlantic tele-phone calls or the equivalent in data,telex, facsimile, graphics, or televisionpictures.
EE
December 1988
OUR RANGE OF MICROCONTROLLER AND EXPANSIONBOARDS IS VASTLY EXTENDED - SEND FOR DETAILS NOW I
8052 -BASICFEATURES INCLUDE* Powerful Erman:ad Basic interpreter* On Board EPROM Programmer,* Program Development from a VDU.* 32K Bytes of CMOS Static RAM,* 32K Bytes of CMOS EPROM
(expandable to 56K Bytes).* Single Unregulated Supply
Requirements.* Small Physical Size 180 by 100mm).* Expansion with range of Compatible
Circuit Boards-* Two RS232 Ports.
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41256414642114611662646225627162532 450ns2732 45Ons2732A 25Ons2764 250ns27128 25Ons27256 250ns27C256 250ns27512 25Ons27C512 250ns
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1 off 25-99 100 up1.00 0.90 0.85Please call for best pricesPlease call for best pricesPlease call for best prices1.75 1.60 1.555.507.75
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Decombe 1988
CUMULATIVE INDEX 1988Audio, Hi-Fi and electrophonicsActive loudspeaker system 4 - 44Automatic volume control 7/8 - S16Background -noise suppressor 7/8 - S56Balanced line driver and receiver 5 - 14D.C. detector 7/8 - S57Digital attenuator 7/8 - S49Digital optical receiver 6 - 19Digital optical transmitter 5 - 17Five -band stereo graphic equalizer 7/8 - S26Four -channel stereo switch 7/8 - S59Fuzz unit for guitars 4 - 33Harmonic enhancer 11 - 41Infra -red headphones 2 - 63LFA-I50 - a fast power amplifier 1 11 20LFA-150 - a fast power amplifier 2 12 42Microphone preamplifier with active filter 9 29MIDI code generator 4 36Philips -Sony digital audio interface 6 14Pitch control for CD players 12 21Portable MIDI keyboard 11 - 30Preamplifier for purists 10 - 30Simple phono preamplifier 7/8 S23Single -chip 150 W AF power amplifier 7/8 S19Stepped volume control 7/8 S58Stereo limiter 1 57Stereo sound generator 4 24Three-way tone control 7/8 S5The Uniphase loudspeaker system 3 36Wireless headphones (receiver) 7/8 S37Wireless headphones (transmitter) 7/8 S36
Computers and microprocessorsAutonomous I/O controller - 1 12 - 3048 MHz clock generator 7/8 - S4864 Kbyte RAM extension for NISX computers 7/8 - 14256 -colour adaptor for the EGA 3 - 24Bus interface for high -resolution LC screens - 1 11 - 56Bus interface for high -resolution LC screens - 2 12 - 12Centronics interface for slide fader 10 - 14Computer -controlled slide fader - 1 3 - 30Computer -controlled slide fader - 2 4 - 60I/O extension for Amiga 500 7/8 - S34I/O extension card for IBM PCs and compatibles - 1.... 6 - 30I/O extension card for IBM PCs and compatibles - 2.. 7/8 - 50LCD for Z80 -driven computers 7/8 - S14Non -interlaced picture for Electron 7/8 - S42Peripheral modules for BASIC computer 10 - 21Plotter - 1 5 - 30Plotter - 2 6 - 24Printer sharing box 7/8 - S30Prototyping board for computer extensions 7/8 - S4Real-time clock patch for DCF77 on the Commodore 64 7/8 - 36Sample -and -hold for analogue signals 7/8 - 17Tracker -ball for Atari ST 11 - 48Universal multiplexer 2 - 18
Components, design ideas and application notesAlternating current source 7/8 - S24Automatic mains voltage selector 1 - 43Background to E2PROMs 12 - 60Computer -controlled music generator 4 - 28Contact encoder as digital potentiometer 10 - 66Copper -on -ceramic microelectronic technology 5 - 21Electronic compass 3 - 60Electrostatic paperholder 6 - 52Field -programmable logic arrays 10 - 41A high-speed depletion DMOS FETfor small signal applications 9 - 42Industry standard moves to CHMOS 2 - 14Logic families compared 11 - 14
Mains signalling 11 - 27A microprocessor -based intelligent multifunction testinstrument 11 - 66MNIICs revolutionize wideband RF amplifier, design 1 - 3SSecond -generation programmable logic 4 - 19Sensors and actuators 3 - 14Simple 1.2 GHz prescaler for frequency meters 10 - 60Single -chip multistandard colour decoder 5 - 57Speech synthesis - 67Stereo sound generator 4 - 24The super capacitor: operation and application 10 - 63
General interestAuxiliary negative -voltage supply 7/8 - S20Car interior light delay 7/8 - S14Car tilt alarm 7/8 - S8Centronics interface for slide fader 10 - 14Computer -controlled slide fader - 1 3 - 30Computer -controlled slide fader - 2 4 -60Computer -driven power controller 7/8 - S25Discrete +5 V to -15 V converter 7/8 - S55Driver for bipolar stepper motors 7/8 - 540Electronic sand -glass 7/8 - S50Fast NiCd charger 9 - 37Fast -starting wiper delay 7/8 - S46Fishing aid 7/8 - S39Flashing light 7/8 - S22Fruit machine 7/8 - S44Headlights indicator 7/8 - S28HF operation of fluorescent tubes 6 - 36High -voltage BC547 7/8 - S12Infra -red detector for alarm system 3 - 22Infra -red remote control for stepper motors 11 - 16Lead -acid battery charger 7/8 - S37Light -powered thermometer 1 - 64Microcontroller-driven power supply - 1 5 - 44Microcontroller-driven power supply - 2 6 - 44Microcontroller-driven power supply - 3 9 - 59Overvoltage protection 7/8 - S55Power multivibrator 7/8 - S29Power switch for cars 7/8 - S47Programmable switching sequence 7/8 - S32Programmable voltage source 7/8 - S16Quiz timer 7/8 - S28Secondary power -on relay 7/8 - S7Self -switching power supply 7/8 - S13Servo -pulse generator 7/8 - S13Single -chip solid state relay 7/8 - S20Stepper motor driver 7/8 - S51Step-up switching regulator 7/8 - S38Switch -mode power supply 1 - 30Timer 7/8 - S21Touch -sensitive light switch 7/8 - S29Ultrasonic distance meter 10 - 37Universal SMD-to-DIL adaptors 7/8 - S35Wiper delay 7/8 - S35
Informative articlesArtificial intelligence 5 - 38Breakthrough in superconducting materials 5 - 22The British Library 9 - 56Chip developed for artificial intelligence 12 - 48Computer and telecommunications revolution willbring its legal problems 2 - 43Computer management systems take over 4 - 17Data encryption 10 - 59Data protection act: keeping the records straight 9 - 57DBS Conference 1988 9 - 32Delicate repairs to costly microchips 10 - 55
.A dish for Europe 11 - 54The efficient alternative to large power stations 4 - 68European education software 1 - 48
Geneva calling: ISDN and satellites at Telecom 87 2 - 34Guiding those waves 12 - 64Holography and lasers produce super -precise measurements 6 - 59International Broadcast Convention 1988 12 - 16Making nuclear waste safe for disposal 10 - 56Making the weather work for you 5 - 53New computer system enhances textile production 7/8 - 64A new multilayer process for integrated passive devices .... 4 - 14Optic fibre communication 2 - 42Optoelect tonics II - 36Paintbox: the high-tech approach to artistic creativity 6 - 42PCB design on the BBC and PC1512/1640 computers 9 - 45Radio communications for the future 4 - 54Readership survey: first results 2 - 45Readership survey results 4 - 42The reason for miniature transducers 3 - 20The rise and rise of the micro 1 - 45Science mobilizes to combat murder in the air 1 - 59Shielding computers with metal -coated glass 9 - 54Signal processing and electronic encryption 5 - 62Simulating sight in robots 5 - 40Sir Clive Sinclair: super electronics entrepeneur 1 - 44Sound recordings archive covers the world 11 - 22Superconductivity: further outlook wanner 4 - 66Synchrotron X-rays reveal how ice flows 1 - 34Telecom 87: a preliminary report 1 - 56Testmex 87: a report 2 - 54Towards the supernode computer 3 - 28The value of silence 3 - 40A very intelligent computer terminal 11 - 39Videotex: a promise unfulfilled? 2 - 39Where industry leans on the shoulders of science 9 - 19A word in the hand makes the measurement firm 3 - 68
Radio, television and videoAmplitude -modulated calibration generator 7/8 - S22The Black Jaguar scanning receiver 7/8 - 62Chrominance-locked clock generator 7/8 - 14Colour test pattern generator 12 - 50Composite-to-TTL adaptor for monochrome monitors 12 - 62Computer -generated colour test chart 9 - 69DCF77 receiver and locked frequency standard 1 - 24Direct -conversion receiver for 80 metres 7/8 - 25Flat aerial for satellite TV reception 2 - 32Frequency read-out for shortwave receiver 7/8 - 39Front-end for FM receiver 1 - 69Front-end for shortwave receiver 1 - 55Ga-As FET converter for 23 cm amateur television 7/8 - 45Intelligent time standard 2 - 22Low -noise preamplifier for FM receivers 3 - 46MacroVision decoder/blanker 10 - 44Microprocessor -controlled radio synthesizer - 1 7/8 - 18Microprocessor -controlled radio synthesizer - 2 9 - 48Noise blanker I - 63OMA-2500 time standard receiver 7/8 - S31Polarotor control 7/8 - S15Reception and transmission of radioteletype 7/8 - 55RTTY filter for 170 Hz shift 7/8 - S6Signal divider for satellite TV receivers 3 - 43Simplified time -signal receiver 11 - 60Slave indication unit for intelligent time standard 3 - 52Tuneable preamplifiers for VHF and UHF TV 4 - 50Video distribution amplifier 7/8 - S54VLF converter 5 - 60Voltage -controlled SHF test oscillator 7/8 - S28Wideband active aerial for shortwave receivers 6 - 55Wideband aerial booster and splitter 1 - 66
Test and measurement31/2 -digit DPM 7/8 - S9Burst generator 7/8 - S33Computer -aided test equipment 12 - 27Deflection detector 7/8 - SIODMM as frequency meter 7/8 - S5Double -trace extension for VLF add-on unit 1 - 32From altimeter to variometer 7/8 - S56Low -frequency L -C oscillator 7/8 - S18Nostalgic sine -wave generator 7/8 - S58Prescaler for multi -function frequency meter 2 - 48
EE 39December 1988
Self-inductance meter 9-24Simple transistor tester 7/8 - S11Test and measuring equipment review - 1(B) 1 - 51Test and measuring equipment review - 1(C) 2 - 56Test and measuring equipment review - 1(D) 3 - 62Test and measuring equipment review - 1(E) 4 - 39Test and measuring equipment review -2 5 - 25Test and measuring equipment review - 3(A) 6 - 62Test and measuring equipment review - 3(B) 7/8 - 30Test and measuring equipment review - 3(C) 9 - 22Test and measuring equipment review - 3(D) 10 - 48Test and measuring equipment review - 3(E) 11 - 63Test and measuring equipment review - 3(F) 12 - 58Test -voltage supply 7/8 - S46Transistor -curve tracer 10 - 50Wideband level -independent trigger preamplifier 7/8 - S45Wideband RF signal tracer 7/8 - S40
Corrections and updatesBASIC computer 2 - 20Ga-As FET converter for 23 cm amateur television 9 58Inductance meter 10 - 65Infra -red headphones 6 - 29Long-range infra -red transmitter/receiver 2 - 20Looking back: stereo limiter; HF operation offluorescent tubes 12 - 67MacroVision decoder/blanker 12 - 55Microprocessor -controlled radio synthesizer 10 - 65MIDI code generator 10 - 65Multi -function frequency meter 6 29Multi -function frequency meter 9 - 58Preamplifier for purists 12 - 55Prescaler for multi -function frequency meter 6 - 29Software update for EPROM emulator (ESS558-A) 1 - 22Software update for PP -controlled frequency meter 1 - 33SSB receiver for 20 and 80 metres 2 - 20
S = supplement page number
88-39
L
December 1988
FULL SUPPORT TO Tit EXCELLENT PROJECTS IN THIS MAGAZINEPL...., %EPS UP;
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T3A-70501- n 0°VET 1:.8115 11.05Srf-a-or 5% -15
=SEM woPly1 F365.00TE10 MiCROCONTROLLER-ORWEN POWER SUPPLY (5:61.8-88):
November 1988K69 1 LFA150 OF pone. arpAher ask us try January 1989.1757; 1525 157,360 . 156.25 ,,,,,,,,, 104171075' F. bed 3-rrn P0.75
complete with all EE PCBs. EE front panel. programed 1070 1 Portable MIDI keyboard F165.00ri.cm .... nis 1C17103.. - P76.75 ,,,,' G7_31718 . F425 8751. rretal ericlosiste. ILP trairsformer 1220 Vl. al ini. proceamrried EPROMTI.C.272 .... 13257C4289A .. F7.00e233E 123_75
(171M- 133 -90ann. - - 1139 COt5172572 . F27.15
Fes-'..,......,, ......, .e.47.- ff- - - ''''Leaden ceramic
T50-2 . . 1375t xx.. 6 13. 75 K71 11 Hannenie enhancer F37.50
K72 BUS .e "I t er I a c a for large LCDs F147.50
displays, serriconductors & passives. tonneClors. marsswitch and plugs_ WOW/I' F845.00ago s4s25 Vil72254 F4550 113 twee .. 10.75 T53-12 FETE TE11 5,4'4nd-cf.-vice meter F99.00 incl. LCD LAI40001
013254 F111.93 197323 - 11500 Sic he 33 12.75 Manse 7015 F4.00 rte. PCB and enclosure SO2 SPECIAL OFFER: 11540001 and H06113038 F75.00F56.50
..Mt336/47/5 1425 CV7226991
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%IOW 7715 14.00FEbmatT 19881(44 Inta-gent tire standard 1345.00
incl. quartz crystal and et -splay; rod. memos trattsformer.
K731 Simpfiferl tin= signed recess:For mare kits. 5-E: our advert on D. 69, EE AkelAuguse 1988We have much wore than cafe be 5sted es Oro achert.
011351 . P41.03%KS . ..1125L11111:11.__ F5_26
1E230KI1518-. - 132-00nCe 13-50 at can 5X0, arm
.acsa ms FAO1. -.x. -a I0x1 y.4.26
'enrol IVA F425D1415 17.15 nO9 - - - 13-63 19eo6 coproccrt 6/110663 Presoaks- for rnulti.furctitre frequercy meet
OV3H tinoA NO 9NICINI/J.SN426.... F1425D,435. ats..75
3010 14.75M17110 F40.03
used n E..i..-a.s.16.25
4322o2-azm see TEST EQUIPMEV
at ernes to rod a kit or an tkierva c= t' C-_, a:. :e s tz i e .,;-, t7.;,-.feet on the grand. and write to else Eutcp.-, d",.1 -r.v .,c,c,s,
mto, 11225pp 5510 Faa2s:47'511... F24_25
4317111 ._163011w.sr 111.50534n3:15 - - FSS11
141° Stkpit' y3.25
Corpert Toro
Apri 1988K49 II Stereo sound gsrerator F57.50K50 Fuzz seal for guitars 164.50'a7211t.... F14.74 R19510. .15975 =sm. 'IAA 1. e.icl. foot switch. C4 Bectrorics P.O. Boa 22089 6360 AB Huth The,05.9.v,_....._ F675 1807-50 . F35.50 1051 Active loudspeakv _ F147.40 Netherlands. Pro--forna iwoices awarol on rtryueSt.%5502 1525 43256420 137.03 56.5-y.ca F6126 ®only parts en PC8I3V30-30
AS poses ate net. in Mitch Guides 11-1FL or 10..G1. subject to chargePr'6'°- M16°EsM4.5 F3.75116653 r'r. 75taapo : t -_, op
KM M. 1/125 3536%3751. MS)
130110/9 - - F5031011010 1503
1/271914.9903-
5101 . . - - - - 56-25V23102-464111
May 1988K52 Pinner wenn! board F78.50
without stars secten
Without price notice, and exclusive of p & p. Pio EITW 1= Dutch VATat 2051 on exported goods. Fast order' Send Eurochelue1 P&P corn -portents: F7.00; kits: 115.00 each.
COMPLETE CVOS.Th. is 6 KT
3961 '53 75 ROBE AVAss4 5 LON& ... 199.00 11553 K53 VLF convertor F35.50 Current stock Est & ordering informaten available against 2 1RCs399' :3 7; Ev,stpiat ha. 1.1140:010 F5100 5231278031-A101 K55 1 BoLthted 761 diner and receiver F97.50 (returned with cfde:). Please state yore Particaar nrolest95.2 fl 75 51100 510321 00113715 11250 AkIP-01 ver&-en KvK 40591
Stepper motor interface board according to Elektor Electronics.Complete kit supplied87167: £36.00Plotter in kit form:£120.00Contains all mechanical parts(filed and turned, not drilled), 3electro-magnets and 2 steppermotors (100 steps/rev.)
HELIUM -NEONLASERLaser tube for exciting visualexperiments:Lissajous figures, holography,etc . .
Colour: redPower: approx. 1.5 mWComplete with 240 V powersupply parts £89.00
with PCB Type
Individual parts:stepper motor:
200 steps £23.00100 steps £11.50
electro-magnet: £ 9.00
MICROCONTROLLER-DRIVEN POWER SUPPLYProbably the world's mostadvanced power supply for homeconstruction, designed by ElektorElectronics, is now available in kitform.
COMPLETE KIT £275.00
pP-Controlled Frequency MeterComplete kit with PCBs 85013 -85014 - 85006.Frequency meter: 0.01 Hz . . 1.2 GHzPulse duration meter: 0.1...100sPulse counter: 0 . . 109 pulsesPeriod meter: 10 ns...100 s
, it,'n 00001A;.
A professional grade frequencymeter, designed by Elektor Elec-tronics, that can be built by manyat affordable cost.
COMPLETE KIT! £147.00Ordering andpayment: Transfer total value of order to
GIRO account no. 4354087(International Postal Order).
Eurocheque (do not forget tosign and fill in holder's guaran-tee card number).
Bank draft on N.M.B. Lin-denlaan Rijswijk Nether-lands. Bank account number669561398.
All payments must be ac-companied by full name andaddress of customer.Postage and packing: £7.50 onall orders.EXPORT: divide total value oforder by 1.20.Meek -it ElektronikaMail Order ServicePaviljoensgracht 35A2512 BL DEN HAAGThe NetherlandsTelephone: ( + 31) 70 609554(only on Fridays, and during nor-mal business hours).
Please mention ELEKTOR ELECTRONICS when contacting advertisers
NEW PRODUCTSVideo display driverMCP now have available the TeledynePhilbrick TP 1900, a high performancevariable gain amplifier that is capable ofdirectly drivig a video display (CRTcathode).MCP Electronics Lid 26-32 Rosemont Road Alperton WEMBLEY HAO 4QY.
ctr
Pre -wired DIN 41612connectorThe ODU KONTAKT 538 series DIN41612 c 64 -pin connectors, of which pre -wired sets can be supplied, are availablefromElectronic Component Marketing Ltd 62Military Road East Sussex TN31 7'NY.
New Look for West Hyde'sInternormWest Hyde's best-selling Internorm casehas been given a new look with the ad-dition of an optional door.West Hyde Developments Ltd 9-10 Park In-dustrial Estate AYLESBURY.
HF silicon MMIC amplifierAvantek have introduced a newMODAMP cascadable silicon bipolaramplifier that offers very flat gain over awide bandwidth. The device is a generalpurpose, 50 -ohm gain block intended foruse in broad bandwidth IF and RFamplifiers.Wave Devices Laser House 132-140 GoswellRoad LONDON EC1V 7LE. For Avantekdistributors outside the UK, see the January 1988issue of Elektor Electronics.
CD test equipmentThe Kenwood range of compact -disc testequipment is now available fromThurlby Electronics. Built for pro-fessional use, the range includes en-coders and decoders, jitter analysers anda subcode generator. A CD test disc isalso available.Thurlby Electronics Lid New Road St. Ives HUNTINGDON PE17 4BG.
Waterproof LED indicatorsBulgin's range of waterproof LED in-dicators come in a choice of threefinishes: matt black, chrome, or satinanodized. They are designed for moun-ting into an 8 mm diameter panel hole.A F Bulgin + Company PLC Bypass Road BARKING IG11 OAZ.
Subwoofer KitThe SUPER PP, a single -cabinet push-pull system using two low -resonancepolypropylene -coned 12.5 inch bassunits, is the latest addition to WilmslowAudio's range of DIY subwoofer kits.Wilmslow Audio Ltd 35-39 Church Street Wilmslow CHESHIRE SK9 lAS.
EE
December 1988
Networking capabilitiesThe Highland Distribution Program-mable Control Group can provide all re-levant hardware and software to meetcustomers' specific networking re-quirements. Full technical support isavailable locally to customers via theHighland national field sales force andregional applications engineers, as wellas from the company's headquarters,where regular training courses are held.Highland Electronics Ltd Albert DriveBURGESS HILL RH15 9TN.
DepletionMede MOSFETs
New depletion -modeMOSFETsSiliconix has introduced a family ofhigh -voltage depletion -mode MOS tran-sistors. These new devices have the nor-mally on -switching aspects of a JFET,and the speed and performancecharacteristics of a MOSFET.Siliconix Ltd 3 London Road NEWBURYRH13 IJL.
Radio test systemMarconi Instruments' Type 2960 radiotest system is now available from In-strumentex. The new system combinesthe Marconi Type 2955 radio communi-cations test set with a single adaptor,allowing it to be used for testing differ-ent systems including Band III radio.Instrumentex Dorcan House Meadfield Road Langley SLOUGH SL3 8AL.
New OTDRA new dual wavelength Optical TimeDomain Reflectometer designed toevaluate both 1300 nm and 1550 nmsingle -mode links has been announcedby Schlumberger Instruments.Schlumberger Instruments Victoria Road FARNBOROUGH GUM 7PW.
42 EE
December 19
8iLFA-150: A FAST POWERAMPLIFIER (FINAL PART)
Protection circuit. The protection circuitserves to: delay the energizing of the output
relay by a few seconds from power -on;
on switch -on, monitor the d.c. resist-ance of the loudspeaker: if this islower than 2.2 ohms, the output relayis not energized;
deactuate the output relay if thedirect voltage across the output ter-minals of the amplifier rises above1 volt;
deactuate the output relay if the peakcurrent flowing in the output tran-sistors rises above 10 A;
from a basic idea by A. Schmeets
deactuate the output relay if one, orboth, of the secondary a.c. voltagesfails-this also ensures that theloudspeakers are disconnected fromthe output when the amplifier isswitched off.
The circuit diagram of the protectionunit is shown in Fig. 9. Note, however,that the output relay and the peak -current detector are located on thecurrent -amplifier board.The 24-V output relay is actuated by T43and T41. These transistors form aSchmitt trigger, so that the relay is ac-tuated when the potential across C4" hasrisen to about 12 V and is de -energized
when that voltage has dropped to about6 V. The hysteresis is determined by R99and RI00.Inverter T42 in the collector circuit ofT4, conducts when the protection circuitis on, and this causes D29 to light.When the power is switched on, C47charges via Rs,. Once the potentialacross the capacitor has reached a valueof about 12 V, T43 begins to conduct.Transistor T43 is then switched on andthe output relay is energized.Capacitor Cr is shunted by transistorT.o, which enables it to discharge veryrapidly if a fault arises. The base circuitof the transistor is connected to a poten-
0279
LOW IMP
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880092 - U -13
Fig. 9. Circuit diagram of the protection unit.
Fig. 10. Printed -circuit board for the protection unit.
Parts list
PROTECTION BOARD
Resistors (.±.5%):1175;R7z;Re1 =15KR76;R99= 100KR78= 2R2R79;R8I =10KReo=3K3; 1.5 W1182;Res;R105=2K2Raa;Ras= 22KRacRe6=100RR87 = 33OR
Res= 150KRso= 27KRe2=3K9; 1.5 WRs3;Ree=56KR94= 12KR96= 15ORR97= 270KRee;R1o4=4K7; 1.5 WR100=1MOR102= 1K5; 1.5 Wli1o1;Rio3=120K
Capacitors:C40 =150nC41;C46= 10y; 25 VC42;C43 = 1p0; 63 VC44;C45=220,1; 25 VC47 = 100d; 40 VC48= 42; 63 V
Semiconductors:D20;023 ... D26 incl.=1N4148021;022 = 15 V; 0.4 W zener diode027= yellow or orange LEDD28=10 V; 0.4 W zener diode029= red LEDDao;Dat =1N4002032=33 V; 0.4 W zener diodeT35;736;T40;T43 = BC546BT37 = BF256AT38= BC639T39;T4I;T42=BC5566ICI =LF411CN
Miscellaneous:K2= 10 -way header for PCB mounting.Two IDC sockets to mate with Kt and K2.PCB Type 880092-3 (see Readers Services
page).
tial divider, R93 -R94 -R93, which is dimen-sioned to ensure that the output relay isdeactuated as soon as one, or both, ofthe secondary a.c. voltages fails. Thejunction R9s-Rios-C4s- is at a negatived.c. potential that is derived from thesecondaries of mains transformer Tr2.Junction R93 -R94 is connected to thebase of T39, which with D32 and R91forms a sort of comparator. Several ofthe protective measures are controlledvia this transistor. When the base poten-tial of the transistor drops below around23 V (56 V minus the 33-V drop acrossD32), Too begins to conduct and the out-put relay is de -energized.The value of the d.c. resistance of theloudspeaker is monitored by ICi. Theinputs of the circuit are connected to aWheatstone bridge, one arm of whichconsists of R75 and the loudspeaker re-sistance, and the other of R77 and R78.Measurements can, of course, only beeffected when the output relay is not ac-tuated, because only then is the voicecoil connected to pins 5 and 6 of connec-tor 1C2 via the relay contacts. Since thed.c. resistance is determined from directvoltages of only a few millivolts, net-work R76 -C40 has been incorporated toprevent error signals arising from am-bient noise. Diode D20 limits the poten-tial across C40.If the d.c. resistance of the loudspeakerdrops below the value of R78 (2.2 52),IC, toggles which causes T3S to conduct.Diode D27 then lights to indicate thatthe loudspeaker resistance is too low. Atthe same time, the base voltage of T39 isreduced to almost zero via D23: the relaycan then not be energized.When the loudspeaker resistance ishigher than 2.2 Q, the relay is energizeda few seconds after power on. The voicecoil is then no longer connected to pins5 and 6 of K2 and ICI can not monitorits d.c. resistance. A fresh check on theloudspeaker resistance can only be madewhen the amplifier is switched on again
EE
December 1988
or another malfunction has caused therelay to be deactuated.The power supply for ICI is derivedfrom the ±56-V lines via zener diodesD21 and D22 and series resistors Rso andR92.The direct voltage at the output of theamplifier is measured by the differentialamplifier formed by T35 and T36. Theoutput signal is fed to T35 via potentialdivider Rsi-R82, and to T36 via a bipolarelectrolytic capacitor formed by Cu andC45. The difference signal across the col-lectors of the transistors is applied tolow-pass section Rs3-Rss-C42-C43. If thed.c. voltage is greater than -±1 V, the col-lector voltage of either T35 or T36 dropsto such an extent that T39 is switched onvia D23 or D24 and this causes the relayto be de -energized via T41. The d.c.operating point of the difference ampli-fier is set with the aid of constant -current source T37. The current is about2.5 mA.Transistors T27 and T30 in the currentamplifier measure the peak voltageacross the emitter resistor of one of theoutput transistors in the positive andnegative half of the output signal re-spectively. The voltage dividers in thebase circuit of T:- and 130 are dimen-sioned to cause the transistors to con-duct when a peak current of 5 A flowsthrough the output transistor. In thatcase, Tv switches on T28, or T30 switcheson T29: in either event, T39 is switchedon (via Dii or Du) and de -energizes theoutput relay, so that the loudspeaker isdisconnected.Power for the protection circuit is takendirect from the ± 56 V lines, but powersupply monitoring diodes D30 and D31are connected to the secondary windingof Tr2 (40 V a.c.).All other connections between the pro-tection circuit and the amplifier aremade via connector K2.The PCB for the protection circuit isshown in Fig. 10. Populating this is notlikely to present any problems.
43
Ancillary PSU board. This board,shown in Fig. 11, is intended to housethe auxiliary transformer, Trip rectifiersD35-D3S, and smoothing capacitors C54and Css. The board is designed to be fit-ted with a number of terminal blocks tofacilitate the inter -wiring of the ampli-fier sections. Make sure that thesmoothing capacitors are rated at 100 V.
ConstructionThe construction details are given for amono amplifier: two are, of course,needed for a stereo amplifier.The heat sink must be at least170 x 80 mm and be drilled in accord-ance with Fig. 8. Its resistance must benot greater than 0.5 K/W. The holes aremade with a 2.5 mm drill and thentapped to receive 3 mm machine screws.
44 EE
December 1988
The enclosure used for the prototypesmeasures 245 x 120 x 300 mm; for astereo amplifier, a larger enclosure isneeded. A small section must be cutfrom its rear panel to make space for theheat sink (see Fig. 1). The heat sink ismounted at a height that allows fittingthe AF input sockets underneath it. Themains input and loudspeaker terminalsare located beside it.Mains transformer Tr2, rectifier Bi, andthe ancillary PSU board are mounted onthe base panel of the enclosure. Theboard for the protection circuit may bemounted on top of the voltage amplifieras shown in Fig. 7 or, alternatively, atanother convenient place in the case.The mains on -off switch and the POWER,ERROR and LOW IMPEDANCE diodes aremounted on the front panel.All components in the current amplifier,except T21:1 to T26 incl., are fitted at thetrack side of the board a few millimetresabove the surface.Inductor Li consists of 12 turns 1.5 mmthick enamelled copper wire on a hollowformer of roughly 15 mm diameter. Re-sistor R63 is inserted into the centre ofthe former and the whole assembly is fit-ted on the board in one go, again a fewmillimetres above the surface.Seven solder pins and a 10 -way connec-tor are used for the remaining connec-tions with the other sections of theamplifier.The terminals of Ten, T21, and T22 arebent upwards 90° about 3 mm fromtheir housing. The transistors are thenscrewed to the heat sink with the aid ofinsulating washers with the terminals up-wards. It should then be possible to fitthe current amplifier board on four 10-mm spacers with the transistor terminalsprotruding through the appropriateholes in the board (see Fig. 5).Next, the terminals of the output tran-sistors are bent as shown in Fig. 13.These four transistors are then fitted onto the heat sink with the aid of insulatingwashers and discs, and plenty of heatconducting paste. Take care that the cor-rect washers and discs are used, becausethe transistors have different cases. Theterminals should coincide with the ap-propriate solder areas on the board.All transistor terminals may now besoldered to the board.Transistor pairs T3 T4; T6:T7; Ts -Ts; andTio-Tii should preferably be matched. Ifthat is not feasible, they should comefrom the same production batch (nor-mally indicated on their body).Pairs T3:1-3 and T6 -T' are mounted onthe board with their smooth sides ad-joining. Some heat conducting pasteshould be applied between each pair,after which the pairs should be tightenedtogether with a nylon cable tie. This isdone to ensure that the two transistors ineach pair have the same temperature andso prevent their d.c. operating fromshifting.
CD in (il 03 (I)cs InDu 0 u 0
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Fig. 11. Printed -circuit board for the ancillary power supply.
The other two pairs are mounted on anL-shaped piece of aluminium, afterwhich the whole assembly (see Fig. 14) isfitted on to the board with the aid of twoshort spacers. Insulating washers andheat conducting paste should be used inthe construction. Solder pins for con-nections A, B, C, and FB should be fit-ted at the track side.When the board is populated, it may bemounted on top of the current amplifierboard with the aid of four 35-40 mmspacers.The mains input plug should preferablybe of the type with built-in fuse. Fromthere, a length of mains cable goes to theon -off switch on the front panel.Another length of mains cable goes fromthe on -off switch to the ancillary PSUboard and Tr2.Make sure that mains -carrying cablesand parts are at correct isolating dis-tance from other parts.The power supply section is wired in ac-cordance with Fig. 12. Note that the sec-ondary (40 V) voltage is applied separ-ately to the ancillary PSU board. Theonly earth point of the enclosure is wiredto the central connection of the20,000 uF electrolytic capacitors.Check whether the two mainstransformers are connected in series byswitching on the mains and verifyingthat the voltage at the ± 70-V terminalsis about 70 V with respect to earth. Ifthe voltage is lower, for instance, 45 V,switch off the mains and interchange thetwo primary connections of Tri on theancillary PSU board. Again switch onthe mains and check the voltage at the±70-V terminals. When everything is inorder, discharge the electrolyticcapacitors carefully with the aid of a470 -ohm, 1 -watt resistor.Solder short lengths of (enamelled) cop -
Parts list
ANCILLARY PSU BOARD
Resistor 1±5%):Rica=1K2
Capacitors:C50 . . C53 incl.= 22nC 54:C55 = 1 000?; 100 VC 55;C 57 = 680:1; 100 VC58= 22F; 25 V
Semiconductors:035 . D39 incl.= 1N4002D4o= green LED
Miscellaneous:Tri= PCB -mount 3 VA mains transformer 2 , 9V; 177 mA.
Ft = fuse 50 mA (delayed action); with PCB -mount holder.
3 off 6 -way PCB terminal block.PCB Type 880092-4 (see Readers Services
page).
Parts list
MAIN POWER SUPPLY(not on PCB)
Bt= BYW66C3t;C32=20,000,r; 63 V (or 2'! 10,000i)F2= fuse 2.5 A delayed action.St = double -pole mains switch.Tr2= 300 VA toroid mains transformer
2 x 40 V; 3.75 A, e.g. ILP Type 73026 1240 Vmains) or 71026 (220 V mains). Availablefrom Jaytee Electronic Services.
Mains input socket with built-in fuseho!der.Heat -sink: thermal resistance 0.55 K'W, e.g.Fischer Type SK47100-SA (Dau Components).
EE
December 198845
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6E6092 - 16
Fig. 12. Inter -wiring diagram for the various sections of the amplifier.
46 EE
December 1988per wire between points A, B, C, and FBon the voltage amplifier and currentamplifier boards.Connect the input socket to the input ofthe voltage amplifier by a short length ofscreened cable.Connect the power input terminals onthe current amplifier board to the take-off points on the electrolytic capacitorsby 2 mm thick insulated copper wire.Use similar wire for the connections tothe output terminals.The supply terminals on the voltageamplifier board are connected to the 70-V terminals on the ancillary PSU board.The protection board is connected to thecurrent amplifier board via a length of10 -way flatcable terminated at both endsinto a suitable 10 -way connector. Makesure that pin 1 of the protection board isconnected to pin 1 of the current ampli-fier board.
Setting upSet PI, P2, and P3 to the centre of theirtravels, and P4 to maximum resistance.Switch on the mains supply. After a fewseconds, the direct voltages at C31- andC32- should be ±58 V w.r.t. earth.Adjust P2 and P3 to obtain voltages of±60 V across R2 and Ras respectively.Adjust Pi to obtain a direct voltage ofexactly 0 V at the junction Li -R63- rei.Adjust P4 to obtain a voltage of 20 mVacross 1b2 and across R. This voltageindicates a current of around 90 mAthrough each output transistor, whichensures trouble -free Class A operation.
Fig. 13. Mounting of the output and driver transistors on the heat sink.
80
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Fig. 14. Construction of the heat sink for
NEW PRODUCTS
8-30 V DC -to -DC convertersROHM Corporation has announced theBP5000 series of DC -to -DC convertersthat are intended for use as supplemen-tary on -card voltage regulators. Appli-cations for these devices, which have aninput voltage range of 8-30 V, includePCs, telecommunications, PC expansionboards, modems and instrumentationequipment.ROHM Corporation 8 Whatney IRVINECA 92718 USA.
Low profile keypadsHighland Electronics can now supplythe Grayhill Series 89 low -profilekeypads. A thin keyboard with facilitiesfor self-legending is also available.Highland Electronics Ltd Albert Drivee BURGESS HILL RH15 9TH.
Biconical antennaThe B-1000 antenna set is a unique andeasy -to -use system for measurementsfrom 30 to 1000 MHz. It combines thebroadband biconical antenna with an
impedance transformer to offer un-paralleled accuracy and covenience ofuse.Fieldtech Heathrow Ltd Huntavia House 420Bath Road LONGFORD UB7 OLL.
Fast precision opampRaytheon Semiconductor has added theOP -47 to its family of high-performanceoperational amplifiers. The new device isdesigned for applications where lownoise (both spectral density and burst),wide bandwidth and high slew rate areprimary requirements.Raytheon Semiconductor Ogilvie RoadHIGH WYCOMBE HP12 3DS.
Octopus workholderFreetrade has announced a price cut tojust £ 5.95 for the versatile Super Oc-topus Workholder. This device holds awide variety of objects at any angle,allowing fine assembly and repair workto be performed with both hands free.Freetrade (TEP) Ltd Unit 15 Avery IndustrialPark Garrison Lane Bordesley Green BIRMINGHAM B9 4QE.
--- .--
32 -channel fibre optictransceiverFiberdata of Stockholm has designed afibre optic transceiver with 32 bi-directional channels. Each channel hasin turn two bi-directional control signallines. The transceiver is completely in-dependent of transmission speed anddata format.Tekelec Ltd Charles House Toutley Road BERKSHIRE RG11 5QN.
Golden Max from STCThe Kemet Golden Max ceramic dip-ped/radial capacitors, ranging in valuesfrom 10 pF to 1µF at 200 V, 100 V, and
EE
December 198850 V, are now available form STC Elec-tronic Services. Encapsulated in amoisture and shock resistant epoxycoating, the capacitors meet the flamerequirements of UL 94V-0.STC ELectronic Services Edinburgh Way HARLOW CM20 2DE
47
Oryx Portasol KitThe scope of this kit extends fromsoldering a semiconductor junction tobrazing a domestic boiler. It requires notraining and replacement or changingthe tip is simplicity itself.Greenwood Electronics Portman RoadREADING RG13 INE.
Radio code analyser forBand IllA new version of the 4922 Radio CodeAnalyser capable of testing mobiles forthe Band III Trunked System has beenannounced by Schlumberger.Schlumberger Instruments Victoria Road FARNBOROUGH GU14 7PW.
Dual -laser fibre optic test setThe Photodyne 2260XF dual -laser testset is designed for use in the installation,maintenance, and trouble -shooting of allfibre optic links operating at the stan-dard wavelengths of 1300 nm and1550 nm.Lambda Photometrics Ltd Lambda House Batford Mill HARPENDEN AL5 5BZ.
32 -bit RISC microprocessorsFour new microprocessor chip sets basedon 32 -bit RISC architectures of SPARCand MIPS and offering up to 20 mips ofcomputing power - five times the per-formance of conventional microproces-sors - have been announced by LSILogic. The new devices will becomeavailable in the first quarter of 1989.LSI Logic Ltd Grenville Place The Ring BRACKNELL RG12 1BP.
Switch fusesAvailable from Highland Electronics isthe ASEA CONTROL range of SEKFswitch fuses. They include DIN, BS,NFC, and NEMA versions.Highland Electronics Ltd Albert Dri.eBURGESS HILL RH15 9TN.
48 EE
December 1988
SCIENCE & 1ECHNOLOGY
Chip developed for Artificial Intelligence
Three chips-an object -oriented mem-ory management unit, a programmablesequencer, and a 40 -bit arithmetic anlogic unit-are said to be capable of for-ming the processor for the world's firstfifth -generation computer, capable toapply artificial intelligence and to oper-ate hundreds of times faster on manytasks than all but the most expensivemainframe computers.The circuits have been designed by LinnSmart of Glasgow Computing and arenow being developed for use in thepopular Sun -3 workstation manufac-tured by California's Sun Microsystems.The development pitches Linn Smarthead -to -head against two United Stateselectronics companies hoping todominate the AI market: the giant TexasInstruments, which has already fieldedan AI board for Apple PCs, and AIspecialist, Symbolics, which is also hat-ching plans to embed its AI chips intoPCs and workstations.Linn Smart makes light of the opposi-tion. They claim that most computers donot understand what they are doingbecause they know nothing of the struc-tures manipulated by the program. Thecomplexity of modern software systems,with their requirements for the securemanipulation of shared, complex datastructures, is beyond their capabilities.They believe that object -orientedlanguages are the solution and theirRekursiv chip set-developed in associ-ation with LSI Logic of Livingston-forms the only machine that can supportthem efficiently.According to Professor David Harlandof Strathclyde University, mastermindbehind the Rekursiv project, mostmodern computers have descended fromthe "beasts" created during the 1940sand are designed to match patterns andbreak codes.
Tough jobsThis means that although modern com-puters are ideal for solving arithmeticalproblems such as bank balances andcalculating pay rolls, they are no good atsolving real life problems such as stockcontrol, image processing and fault diag-nosis. These are tough jobs for conven-
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tional computers, specifically designedto do simple number -crunching.Explained Professor Harland: "Youneed machines that know what they aretrying to do rather than ones that needto be told exactly how to do things. Backin the 1940s they wanted computers forpattern matching and the emphasis wason numerical calculation. But numbersare simple and you only ever want to doa small range of short operations."Computers evolved that were very welladapted to the job of executing a smallset of simple actions on straightforwardnumbers. Indeed, the current fermentabout the so-called reduced instructionset computing (RISC) technology chipsis really about taking this process to itslogical conclusion and using the smallestpossible set of the simplest possible in-structions.RISC chips are very fast at arithmetic,and computers built from them are goodat jobs that can be easily turned intomathematics. The computer has to dolots of relatively simple sums involving
numbers that represent little more thansimple quantities.The problem that arises is that the worldis not made up of numbers: it consists ofactual solid objects interrelated in manydifferent ways. And if computers are tosolve problems in the real world, theymust be designed to cope with these ob-jects.Young children have no trouble at all intackling problems that would stump acomputer such as stacking toy bricksinto piles. Indeed, stacking crates intowarehouses or containers on to ships isexactly analogous to toy bricks.
Object orientedBut when it comes to shipping crates outof a warehouse, the fact that there is atelevision in one and a hi-fi in another isvital. The computer has to deal withmore than a simple quantity: it musthandle a complete description of the ob-ject; everything from what it is andwhere it is stored to the address of the
purchaser.In other words, a whole mass of infor-mation or data is needed to describeeach crate or object precisely enough sothat it can be handled correctly. Com-puters able to cope with this type ofproblem are called object -oriented com-puters. This is because they manipulatelarge amounts of data that describe par-ticular objects or relations between ob-jects as single entities.This data is encoded in the form ofbinary numbers up to 40 bits long in theRekursiv computer board. But thesebinary numbers encode abstract descrip-tions of objects and are not just simplequantities. And because of this, theselarge binary numbers or data objectsmust be manipulated in special ways byinstructions far more complicated thanthe simple adds and multiplies used inconventional computers.Linn Smart engineer Duncan McIntyrecan see many applications for Linn'stechnolog. "An obvious one is in largedatabases where we can deal with data
far more effectively and efficiently andin a way that is much more manageablethan with conventional systems," hesaid."In the financial community, the per-sistence of data this system offers makesit useful for trading. It is also useful fordesign engineers who would benefitgreatly from the object -oriented natureof the machine because they coulddefine any part of their design as a singleobject and manipulate it as a whole."
Fast memoryThis may be one reason why Linn Smartis making its first products for the Sun -3workstation which is now finding its wayinto City of London dealing rooms aswell as development laboratories. TheRekursiv chip set has been mounted onto a triple height super extendedEurocard-ideally suited to the VME-bus slots in the Sun -3 chassis.The board carries 40 Mbits of DRAMmemory-enough to store some 40
EE
December 1988
million different objects-as well assome fast SRAM memory that containsa kind of directory helping to locate theexact position of particular data objectswithin the computer's memory.TheRekursiv computer chip set has beenunder development for several years andis now about to be launched on to themarket.The chips at the heart of the Rekursivare manufactured in 1.5 p CMOS tech-nology by LSI Logic, and Linn Smarthave a manufacturing deal with a majorBritish printed circuit board maker toput the slot -in board into production.Linn Smart have also developed a pieceof software that runs on a Sun -3 work-station to simulate the behaviour of itsboard, although it cannot imitate theamazing speed of the device.The market for embedding AI into con-ventional computers is enormous, butthe prospects for Linn Smart's world-beating technology depend on how gooda fight the company can put up againstits United Stated rivals.
49
PEOPLEOn the 1 October last, the followingtook office at the IEE for the 1988/89session:President - Dr T. Bryce McCrirrick,
CBE, FEng, FLEE, formerly Directorof Engineering, BBC.
Deputy Presidents - James C. Smith,CEng, FLEE, Chairman Eastern Elec-tricity Board, and Dr. David A.Jones, CEng, FLEE, formerly Chair-man, Ewbank Preece Consulting Ltd.
Divisional Chairmen -Computing & Control Division:Dr. Nigel W. Horne, BSc(Eng),FEng, FIFE.Science, Education & TechnologyDivision: Professor Brian Makin,BSc(Eng), PhD, CEng, FIFE.Electronics Division: Professor JimR. James, BSc, PhD, DSc, FEng,FLEE.Management & Design Division: AirCommodore Frank C. Padfield,CBE, BSc, CEng, FIFE.Power Division: Mr William Fairney,CEng, FIFE.
The Rt Hon The Viscount Weir, Chair-man, The Weir Group PLC, has beenelected the 1988/89 President ofBEAMA, the Federation of British Elec-trotechnical and Allied Manufacturer'sAssociations.
LSI Logic Corporation has established aMicroprocessor Group and named BrianHalla as vice-president of the organiz-ation.
David Baillie has been appointed Direc-tor of Marketing Strategy for LSI LogicEurope PLC.
Gould Electronics have announced twosenior management appointments. BillTrebinski, formerly Director of Oper-ations for Northern Europe, becomeVice -President, Sales & Marketing; andChris Chant, formerly Director ofMarketing, becomes Director ofManufacturing.
Mr John Mark, 53, has been appointedTechnical Director of Marconi RadarSystems, Chelmsford.
Intel have announced the appOintmentof Sean Maloney as UK RegionalManager.
David Kingsley has been appointed asTechnical Director of Graphic Elec-tronics Group, the well-known printed -circuit board manufacturers.
50 EE
December 1988
COLOUR TEST PATTERNGENERATOR
from an idea by G. Kleine
A PAL -compatible colour video source that supplies a number oftest patterns for aligning television sets.
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A test pattern generator is virtually in-dispensable for troubleshooting in tele-vision sets because it supplies a videosignal that is known to be stable, andthus easily displayed and synchronizedon an oscilloscope. Moreover, the instru-ment allows the user to trace a fault in aTV set or other video equipment byselecting the most appropriate test pat-tern (e.g. a cross -hatch for convergencetesting, or a dot pattern for focusing ad-justment).The test pattern generator discussed hereis based on three integrated circuits: apattern generator (ZNA234E from Fer-ranti), a video matrix chip with DAC in-puts (LM1886) and an associated videomodulator (LMI889). The latter twochips are manufactured by NationalSemiconductor.
Block diagramThe general set-up of the pattern gener-ator is shown in Fig. 1. In principle, allpatterns originate from the ZNA234E,which supplies the luminance infor-mation for a dot pattern (DOT), a cross-hatch pattern (XH), a horizontal line
pattern and a vertical line pattern. Thevertical bar pattern supplied by the chipis not used here because it is unsuitablefor generating a colour staircase signal- this is derived from the vertical linepattern.The output signal supplied by the pat-tern generator circuitry is monochrome,i.e., it contains only luminance infor-mation. Colour is obtained by applyingthe luminance signal to one or more in-puts of the RGB generator. RGB signalsare fed via two switches to a colourmatrix. The first switch selects betweenthe vertical bar pattern and the otherpatterns. The second switch disables thecolour burst and thus allows the colourstaircase to be made monochrome, i.e.,to be converted to black, white and in-termediary shades of grey. The otherpatterns can be viewed in black andwhite also by turning on red, green andblue simultaneously. The monochrome
patterngene atorZNA234E
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bargenerator
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video
1kHz oscillator 0
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VHF
burstoscillator
881130 -11
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/colour switch provides the three 3 -bitD -A inputs of the colour matrix with anRGB signal whose composition results in8 colours or 8 shades of grey.In the colour matrix, the RGB signal istranslated into the corresponding levelsfor the luminance and chrominancecomponent. Colour coding is essentiallyto the PAL (phase alternation line) stan-dard. The LM1889 combines the signalssupplied by the matrix with that of thecolour burst generator. The compositevideo signal thus obtained is available ata buffered output. An RF modulator onboard the LM1889 modulates the com-posite video signal plus a 1 kHz audiotest tone on to a carrier in the VHF -1band (approx. 48 to 65 MHz; now nolonger used in the UK). An externalUHF modulator is required for testingTV sets tuned to channels in the UHF
band. The pattern generator provides a625 -line picture.
Circuit descriptionThe circuit shown in Fig. 2 is not nearlyas complex as it looks at first sight. Infact, it is fairly simple, and merely acombination of smaller sub -sections,whose basic function has been discussedabove.Circuit IC3 provides the pattern signalsand two synchronization signals, mixedsync (MS) and mixed video blanking(MVB). The switch that feeds the pat-terns to the colour generator is formedby IC4, an 8 -to -1 multiplexer. Actually,the circuit referred to as 'colour gener-ator' is composed of three NANDswitches, Ni, N9 and Nto. The verticalbar pattern is generated by counter ICs.
EE
December 1988Circuit IC12 is the vertical bar/patternswitch.The monochrome/colour switch builtaround IC13-1C14 drives the videomatrix, IC's, and the modulator, 1C19.The 1 kHz test tone oscillator set uparound T2. This is switched on and offby the logic level at the QA output ofIC54 (0 = off; 1 = on). Preset Pi is ad-justed for optimum stability of the oscil-lator.The burst oscillator on board theLM1889 operates at the PALchrominance subcarrier frequency,4.433 MHz, with the aid of an externalquartz crystal and a capacitor network.The user interface of the test patterngenerator is formed by push-buttonswitches S3 to Si. Each of these controlsa function with the aid of a JK bistable(FF3 to FF6). Key debouncing is
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EE
December 1988
R2MSB 0Rt
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00
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Fig. 3. Electronic switches connect the RGB DACs in the LM1886 in two ways: as RGB-TTLinputs (Fig. 3a; colour), or as 3 -bit intensity inputs (Fig. 3b; monochrome).
achieved with a combination of aSchmitt -trigger gate (N2 to N5) and anR -C network. The logic level at outputsQ and Q of each bistable toggles everytime the associated key is pressed. LEDsconnected to the bistable outputs showthe currently selected mode of the pat-tern generator.The pattern generated by the circuit isselected by S2, whose debounced pulsesclock counter ICs.. An auto -repeatfunction is provided on S2. The leastsignificant bit supplied by the countercontrols the I kHz AF oscillator, so thateach pattern is available with or withouta test tone. The three most significantcounter bits control the pattern selector,the vertical bar/pattern switch, themonochrome/colour switch, and thepattern indicator formed by 106 and in-dicator LEDs D6 to D13.
Before the function of the controlsignals in the circuits is discussed, it isuseful to examine the operation of thecolour switch.The simplified diagram of Fig. 3a showsthe configuration of the six toggleswitches (IC13-1C14) between 1C12 andICis, when 'colour' is selected. Eachbasic colour has only two shades (satura-
tion minimum or maximum), since theinputs of each DAC are interconnected.For test purposes, this arrangement stillresults in enough colour combinations.The switch configuration for`monochrome' is shown in Fig. 3b. Theinputs are connected such that only one`colour', white, is available, but theintensity can be controlled to give greyand black - the RGB information ap-plied is simply used as a 3 -bit luminance(Y) signal.
Returning to the control circuitry of thetest pattern generator, D1, D2 and R7provide an OR function that controls thevertical bar/pattern selector, IC12. Alogic high level supplied by Di -D2 -R -selects the RGB signal from gates Ns toNio; a logic low level, the signal fromthe vertical bar generator. The fourthswitch contact in ICiz controls themonochrome/colour selector. When1C12 is set to 'pattern', .103 and IC14 areset to the 'colour' position (note that thisdoes not exclude a monochrome picture,since red plus green plus blue giveswhite). When 1C12 is set to 'pattern', themonochrome/colour and colour selec-tion depends on the logic level at the QBoutput. When this is low, IC13 and 1C14
are in the 'colour' position, so that thecolour bars are generated. A high level atQB selects the staircase signal formonochrome applications.As already noted, the bar pattern(monochrome as well as colour) is de-rived from the signals supplied by IC3.The pattern is basically generated by theluminance signal for the vertical line pat-tern, which is coniposed of a number ofpulses at fixed intervals in each line.These pulses are used for clocking a 4 -bitcounter. Since the three most significantbits function as RGB outputs, the colourobtained changes with every secondpulse applied to the clock input. TheRGB information remains the same inbetween two pulses, so that a colouredbar is obtained. Between two lines IC36is reset by the inverted MVB signal (N7)to ensure that the counter has the samestart state (nought) at each line.Signals burst enable, BE, H/2, and abias signal are combined with theavailable RGB signals in ICis. Thechrominance subcarrier generated byIC19 is applied to the bias input, pin 7,of ICis. The other two signals, BE(burst key) and H/2, are obtained withthe aid of monostables MMVi toMMV4, and bistable FF2. Signal H/2 isthe line toggle signal that inverts theR-Y signal for each line in the PAL pic-ture. FF2 is synchronized by MMV4 to
Fig. 4 Oscilloscopeone picture line in(Fig. 4a) and onemonochrome staircase pattern (Fig. 4b).
photographs showingthe colour bar pattern
picture line in the
EE 111December 1988
ensure that the temporarily doubledhorizontal sync -pulse rate in the verticalsync interval does not upset the PALtiming.
The Y -output of IC19 carries a colourCVBS (composite video, blanking,synchronization) signal. The photo-graphs in Fig. 4 show oscillograms ofone picture line in the colour bar pattern(Fig. 4a), and one line of themonochrome staircase pattern (Fig. 4b).The CVBS signal is buffered by anamplifier around T4 to T6, to enabledriving a 75 Q load.
Unfortunately, the RF modulator con-tained in the LM1889 can only operate atVHF Band 1 channels (2 to 4). Vestigialsideband suppression is not provided -the RF spectrum generated is simply thatof a DSB (double-sideband) modulator.The frequency of oscillation is deter-mined by an external L -C tank circuit,C13 -C33 -L2. The modulator is drivenwith the CVBS signal and the FM soundcarrier, whose frequency is set to6.0 MHz (UK) or 5.5 MHz. Like thechrominance and the RF carrieroscillators, the sound subcarrier oscil-lator is also contained in IC19. Fre-quency modulation is achieved with theaid of varicap D3 which forms part ofan external L -C tuned circuit, L i-Cls-C19.
Switching between a colour andmonochrome picture is effected by press-ing the BURST ON/OFF button (togglefunction). The quartz -crystal controlledchrominance subcarrier oscillator isdisabled when T3 conducts.
ConstructionThe printed circuit board for the testpattern generator, shown in Fig. 5, is adouble -sided, but not through -plated,pre -tinned type with a large groundplane at the component side to keepdigital interference within limits. All in-tegrated circuits are fitted on to the PCBwithout IC sockets. In some cases, com-ponent terminals (including IC pins) aresoldered at both sides of the board to ef-fect through -contacting.Commence the construction with install-ing 11 short pieces of through -contactingwire in the vicinity of the boxed EPSnumber at the component side. Mountand solder one component at a time, andcheck that pins or terminals, where ap-propriate, are soldered at both PCBsides. Use a soldering iron with a finetip.RF inductor L2 consists of 6 turns of1 mm dia. (SWG20) enamelled copperwire. The internal diameter is about6 mm. Space the turns evenly so that thewire ends can enter the holes provided.The photograph of the prototype inFig. 6 shows that the RF section of thecircuit is screened with 20 mm high tin -
Vertical lines.
Horizontal lines.
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Cross -hatch pattern.
Dots.
Monochrome staircase pattern.
Faultfinding in TV setsA test -pattern generator is a videosignal source intended for locatingmalfunctions in TV sets and videoequipment. Below are a number ofpossible applications of the instru-ment described in this article.
Convergence:Convergence is the intersection, at aspecific point at the inside of themultibeam picture tube, of the R(red), G (green) and blue (B) electronbeams. Convergence errors areusually observed as beam divergencein the picture corners, where anoriginally white, single, line divergesin two or more, coloured, lines.Required test -patterns: cross -hatch orvertical lines.
Focusing:Focusing and convergence ad-justments usually interact, but mayuse different circuits in the TV set.An improperly focused picture ap-pears blurred and hazy. Like con-vergence, focusing may have to be op-timized with the aid of separate ad-justments that work on parts of thescreen.Required test -patterns: dots, cross-hatch and vertical lines.
RGB amplifiers:Given that the picture tube still hasequally active R, G and B emitters,these should have closely matchedDC amplification characteristics toprevent colour distortion.Required test -pattern: colour bar(luminance of individual coloursdecreases: white, yellow, cyan, green,magenta, red, blue, black).
Uniform saturation on wholescreen:The background colours without atest -pattern enable checking foruniform colour saturation in all areasof the screen. Light spots point toageing effects in the picture tube.
Burst:A monochrome picture is generatedwhen the colour burst is turned off.This ability of the pattern generatormay be useful for troubleshooting thecolour demodulator and chromi-nance circuits.
54 EE
December 1988
Parts listResistors (=5%):Ri;f12;1131=10KR3;Re:R2;R1e;Fl1 2;R ia;R21;R2e:Rae;R36;
R38= 1K0Re:Fla:Flto:R 1:R23:R22:R32:R3e= 2K2Re= 22RRa = 6808R12=8K21113:R14=27KRte;R2a;Rae=4K7R ts;R22:R32= 3K3Rao = 100R
R24 = 220KR2s = 22K
R291130=15KR33=1K8R40 =330RRe I = 1K2
R42;R43 = 270RRee=82ORRea=82RRea = 68R
Pi =50K preset H
Capacitors:Notes:
AU ceramic capacitors (<1 nFl: pitch 5 mm.Ad electrolytic capacitors: radial unlessotherwise noted.
C1=47pC2:C12;C25:C43 . . C53 Incl. =47nC3;Cts;C2e;C33= 40p foil trimmerC4=470; 25 VC5= 100ii; 25 VCe;C7;Ca;C27= 10ki; 25 VCs=330pCio;C2I;C24 = 22nC11;C22;C23;C32=1011C13=33pC1e;C15=100pC16;C2o;C34;Caa;Cas=100nC12:C3o;C31 =39pCts=27pC26=4;i7; 25 VC2a;C32;C3s=4p7; 25 V; axialC36= 100;1F; 35 VCoo= 1000;;F; 35 VC41=1(10C42= 220p
Semiconductors:
D1;D2:104;fle=1N4148D3=BA124 or BB109G
incl.;023= LED 5 mm (rectangularLEDs possible for Da to D13)
016= LED; 5 mm; green017= LED; 5 mm; redD18= LED; 5 mm; yellow (blue preferred)D . . .D22 incl. = 1114001TI;T2=8C547T3=BF494Te;Te = BF 1 99
Ta=BF256BIC1=7812IC2= 7805IC3=ZNA234E (Ferranti)±IC4 = 74HCT 1 51PICe;IC23=74HCT393PIC6=74HCT42P1C2;1Cs;IC1e;IC21;IC22=74HCT73P1C9:1C11 =74HCTOO
ICio=74LS14IC12= 74HCT 158P1C13:1C re = 74HCT1 57P
IC16:1C17=74HCT221PICIa=LM1886N-1C1e=LM1889N-1C2o=74LS132
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1-12. 5. Component mounting plan of the double -sided printed circuit board.
- Listed by Cricklewood Electronics andUniversal Semiconductor Devices.
Inductors:Li =L2 = home-made inductor; see text
Miscellaneous:St = double -pole mains switch in mainsentrance socket with built-in fusehoider.
S2...Se incl. = push -to -break button.
Xt = 5 MHz quartz crystal in HC18 enclosure.X2 = 4.433619 MHz quartz crystal in HC18enclosure.
BNC socket.Common heat -sink los ICI and IC2.Fuse: 100 mA delayed action.Mains transformer 15 V; 400 mA.Metal enclosure: approx. size 25 v 8 z 18 cm.TV coax socket.PCB Type 880130 (see Readers Services page).
EE
December 1988plate sheets, which are joined in the cor-ners, and soldered on to the groundplane. The screen that runs along IC14-IC17 and ICIs-ICis can only be solderedin the corners and close to Cie becauseof the tracks running beneath it. Trim-mer C29 is to be mounted a fewmillimetres above the board surface toprevent overheating of the PTFE foilwhen the two rotor connections aresoldered to the ground plane.Finally, on ready-made board 880138,connect pins 1, 2, 3 and 14 of IC22, andpin 1 and 2 of IC2t, to eround.
Setting upThe video part of the test pattern gener-ator is fairly simple to adjust. Connect acolour monitor with a 75 Q CVBS inputto the corresponding output of the cir-cuit. Set all trimmers to the centre oftheir travel, and turn the wiper of Pt toground. Press the BURST ON/OFF keywhen D15 lights. Carefully adjust trim-mer C29 for minimum interference be-tween the coloured bars.
As already noted, the VHF modulator isonly for use with a TV set on whichVHF Band 1 is available.Tune the TV to, say, channel 3 (inEurope, TV channel E3=55.25 MHz).Adjust C33 until the test pattern ap-pears. If available on the TV set, use the
Fig. 6. The completed board (prototype). Note the screening around the RF sections.
fine adjustment to obtain a clear picture;otherwise, carefully adjust C33 with aninsulated trimming tool. Turn up thevolume on the set and adjust C19 forminimum AF noise. This tunes thesound oscillator to the correct subcarrierfrequency (6.0 MHz or 5.5 MHz, de-pending on the country you live in).Press S2 if D14 does not light. Carefullyadvance Pt until the test tone is heard inthe receiver. Increase the frequency and
the volume by turning Pi, up to a pointwhere the tone becomes unsteady. Turnthe wiper back until the steady tone isrestored at maximum volume.
0 0 0e
0 0 0 0r
0 CJ '
TV Pattern Generator 0 0 0 0
Fig. 7. Suggested front panel layout.
CORRECTIONS
Preamplifier for puristsOctober 1988, p. 30-36.
In the top drawing of Fig. 4, the 47 pF capacitor acrossRat should be labelled C25, not C2a. In the lowerdrawing, the 471(5 resistor to the left of Ras should belabelled R37.The accompanying diagram shows the corrected com-ponent mounting plan of busboard 1 (Fig. 6 on p. 33).Note the placement of points M and N, and the con-nections between the tuner input terminals and pointsE and F.
Macro vision decoder/blankerOctober 1988, p. 44-47.
The RSYNC LED, Ds, may fail to light even when avideo signal of sufficient amplitude is applied. This canbe resolved by replacing the Type 7805 voltage regu-lator in position IC4 with an 7806 or 7808. whichhave the same pinning. The use of an 7808 requiresR ia to be increased to 15 k4.
56 EE
December 1988
New LiteratureCby Mike BurgessISBN 1 870336 16 X512 pages - 210x145 mmPrice £14.95 (soft cover)C, a book in the A Dabhand Guideseries, will give even relatively unex-perienced programmers a clear under-standing of programming in C. In nofewer than 37 chapters, the bookdescribes all possibilities contained inthis high level language.The book is, of course, not dedicated toany one computer, because C is a univer-sal programming language that has to betranslated in a compiler into the actualprogram for a particular computer. It isbecause of this that users of not only anIBM PC or compatible, but also of aCommodore Amiga, an Atari ST, a BBCMicro, and an Archimedes, to name buta few, will find much valuable infor-mation.Unlike the situation with hardware,characterized by a lack of standardiza-tion, that in regard of software is muchbetter, and this book shows it. Wherethere are differences in the compiler, thereader is given a helping hand by the ad-ditional options given in the book.Optionally available is a programmedfloppy disk that contains the programsdescribed in C. This disk is supplied witha short manual.Mark Burgess holds an Honours Degreein Theoretical Physics. He writes com-puter programs in over half a dozenlanguages of which C is his favourite. Heis the inventor of the Burgess ProgramStructuring which is explored in thisbook.Dabs Press (RU) 76 Gardner Road Prestwich MANCHESTER M25 7HU.
Musical Applications of theAtari STsby R.A. PenfoldISBN 0 85934 191 790 pages - 263 x 193 mmPrice £5.95 (soft cover)With its built-in MIDI ports, large mem-ory, excellent graphics, high processingpower, it is, perhaps, not surprising thatthe Atari STs, according to most in-siders, are now the computers to use forelectrophonic music applications. Therange and sophistication of these appli-cations are greater than most people mayrealize. This book will help them get themost, musically that is, from the STs.The book is intended for the musicianwho wants to exploit the potential of theST computers in music applications. Asthat usually means using the ST in MIDIsystems, much of the book is devoted toa description of MIDI in general, MIDI
as it applies to the ST, and runningMIDI applications on the ST.The book assumes only a basicknowledge of running software on anST. None the less, more technicallyminded readers who like the do-it-yourself approach will find chapterscovering hardware projects, program-ming the ST's sound chip, and MIDIprogramming.BERNARD BABANI (publishing) LTD TheGrampians Shepherds Bush Road LONDONW6 7NF.
Soldering Handbookby Ray SkippISBN 0 632 02064 4188 pages - 240x 160 mmPrice £29.95 (hardback)Soldering is a basic and indispensableprocess for all involved in electronics.This thoroughly practical book is in-tended to guide engineers and techni-cians through the various solderingsystems, to guide them towards the cor-rect system to be used and to help avoidpitfalls and solve the problems that willoccur along the way. It will also be ofgreat help to all involved in electronicquality control.In 12 chapters, the books covers, amongothers, the theory of soldering, handsoldering, flow soldering, surface mountassembly soldering, de -soldering tech-niques,and the cleaning of printed -circuit boards.The book is structured in a logical se-quence, starting with simple manualsoldering techniques, and progressingthrough flow soldering systems to thelatest microelectronic soldering tech-niques.Ray Skipp has been involved directlywith the setting up and running of prac-tical quality control systems in a numberof electronics companies, both as a qual-ity manager for many years, and for thepast nine years as a consultant.BSP Professional Books Osney Mead OX-FORD OX2 OEL.
ARCHMIDES ASSEMBLYLANGUAGEby Mike GinnsISBN 1 870336 20 8368 pages - 210 x 145 mmPrice £14.95 (soft cover)This book, one of theA Dabhand Guideseries, covers all aspects of machinecode/assembler programming for theArchimedes range.In 24 chapters, the book describes theARM (Acorn RISC) processor used inthe Archimedes, the machine languagefor various applications, such as I/O,graphics, dataprocessing, and so on.There is also a large section 'on thepowerful assembler incorporated in theBASIC of the Archimdes, and thus ac-
cessible to all users of the computer.The contents make the book a welcomeaddition to the manual provided withthe computer and will, no doubt, be aninvaluable source of information formany owners of an Archimedes.Optionally available is a programmedfloppy disk that will give furtherevidence of the power of the assembler.Mike Ginns, who read computer scienceat Reading University, has been pro-gramming the BBC Micro and manyother computers in assembly languagefor many years.Dabs Press (RU) 76 Gardner RoadPram -hi& MANCHESTER M25 7HU
Remote Control Handbookby Owen BishopISBN 0 85934 185 2226 pages - 178 x 110 mmPrice £3.95 (soft cover)This book is more than an update ofRemote Control Projects published eightyears ago: in view of the many advancesin electronics in the intervening years, ithas become a virtually new book. Nonethe less, it retains some of the well -triedand tested circuits for which compo-nents are still available today.A number of circuits in the book havenot been published before. Many ofthese are concerned with aspects ofremote control, that have increased in im-portance over the past few years. In par-ticular, there are circuits for interfacingmicrocomputers to remote controlsystems, for using fibre optics, and forusing the domestic mains wiring systemas transmission links. There are also cir-cuits for stepper motors, voltage -to -frequency conversion and frequency -to -voltage conversion.The book assumes that readers arealready familiar with the mechanicalaspects of the devices they wish to con-trol, and it is, therefore, restricted to theelectronic aspects of remote control.BERNARD BABANI (publishing) Ltd TheGrampians Shepherds Bush Road LONDONW6 7NF.
The 1989 Cirkit Industrial Cataloguecombines helpful design changes withdetails of significantly expanded productranges from leading international sup-pliers represented by the company.Copies of the catalogue are available freefromCirkit Distribution Ltd Park Lane BROX-BOURNE ENIO 7NQ Telephone (0992 44411.
Siliconix has produced a new supple-ment to its integrated -circuit databookcovering the company's range of300 MHz DMOS Wideband Switchesand Multiplexers.Siliconix Ltd 3 London Road NEWBURYRGI3 1JL Telephone (0635) 30905.
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December 1988
BOOKS FROM ELEKTOR ELECTRONICSMICROPROCESSOR DATA BOOKThis book has come about because of a need by Elektor Electronicsengineers, technicians, and editorial staff of a ready reference workon the most important microprocessors. This implies that it does notonly contain information on the latest devices, such as the trans-puter, but also on older, well -established types, such as the Z80 andthe 6800.A general description, hardware block schematic, software structure,DC characteristics, and instruction sets are given for over 70microprocessors. To prevent the book from becoming unwieldy (andto keep costs down) timing diagrams and AC characteristics have,however, been omitted. The detailed information on all manufacturersmentioned will, however, enable any additional information to be ob-tained quite readily.Included in the book are, among others: the 68000 series the 6502 family Z80; 8080; and 8085 Intel's 8086; 80186; 80188; 80286; 80386 the NS32XXX series the INMOS transputers
ISBN 0 905705 28 9Price £8.95
302 CIRCUITSThe popularity of this book is shown by its having been reprinted nofewer than three times. It offers a selection of the most interestingarticles from the 1982, 1983, 1984 summer issues of ElektorElectronics.In it you will find circuits for audio and video; car, cycle, and motor-cycle; home and garden; receivers and aerials; hobbies and games;measuring and testing; oscillators and generators; current sourcesand power supplies; microcomputers and music electronics; and amiscellany of other interesting subjects.
ISBN 0 905705 25 4Price £6.25 net
303 CIRCUITSLike its predecessors, 303 CIRCUITS offers a comprehensive collec-tion of practical ideas, concepts, and developments in the gamut ofelectronics. Unlike its predecessors, the book is arranged in 11 sub-ject sections to make it easier for the reader to find that long -soughtcircuit.In well over 300 pages, the book offers 32 Audio & Hi-fi projects; 14circuits for Car & Bicycles; 43 Computer & Microprocessor circuits;11 Electrophonic projects; 24 HF & VHF circuits; 16 circuits for anumber of hobbies & pastimes; 54 projects for Home & Garden; 29Power Supply circuits; 29 circuits for Test & Measurement equip-ment; nine TV & Video projects; as well as 42 Design Ideas.
ISBN 0 905705 62 2Price £7.95 net
DATA SHEET BOOK 2Like its predecessor (now out of print), this book offers concise, rel-evant, and rapidly accessible information, which is both practical (e.g.,the pin -out of a device) and informative.The book contains data on integrated circuits as well as on discretetransistors and diodes. Moreover, it gives an introduction to fast(HCMOS) devices and a review of the new symbolic logic as laiddown in British Standard 853939:Section 21 (IEC Standard 617-12).The final part of the book deals with a number of computer chips,such as memory devices (including programming information forthese) and I/O circuits. This section also includes data on a numberof non -digital discrete and integrated devices, such as op -amps, aswell as on some microcomputer peripherals (e.g., the 6522 VIA, the6580 ACIA, and the 8355A PPII.
ISBN 0 905705 27 0Price £8.25 net
These books are all available direct from Elektor Electronics through the Readers' Services, from a number of bookshops and electronicsretailers in the UK, and from selected bookshops throughout the world.
NEWSHIGH TECHNOLOGYINSTITUTIONS MERGEOn the 1st of October last, the Insti-tution of Electrical Engineers and theInstitution of Electronic and RadioEngineers formally merged. The newbody retains the long-established titleThe Institution of Electrical Engineersand becomes the largest of the UKChartered Engineering Institutions witha membership of over 105,000.The new institution will continue tocover the art, science, and practice ofelectrical, electronic, and softwareengineering in such fields as Power, Con-trol, Instrumentation, Broadcasting,Radio, Telecommunications, Com-puters, and Information Systems.The institution, whose members rangefrom students to chief executives, will actas the voice of the Electrical and Elec-tronic Engineering Profession in all mat-ters of public concern. It will also speakwith greater authority to Governmentand other influential bodies, both in theUK and overseas.The merger of the two institutions willalso lead to an enhanced and broadenedrange of Learned Society activities andthe adoption of common standards forprofessional qualifications.
INMARSAT SPEEDS START OFSMALL -TERMINAL SATELLITESERVICEThe London -based InternationalMaritime Satellite Organization (IN-MARSAT) has awarded three five-yearcontracts worth a total of £722 million toBritish Telecom International (BTI),Telecoms Singapore, and the HellenicTelecommunications Organization(OTE). The contracts, for Standard -Csystem network co-ordination station(NSC) services, will speed the introduc-tion of global satellite communicationsby small, portable and mobile terminals.BTI already has a coast earth stationworking with the INMARSAT AtlanticOcean satellite, the OTE station at Ther-mopylae works with the Indian Oceansatellite, and the Singapore station withthe Pacific Ocean satellite. When oper-ational, the Three NSC stations will sup-port a fully operational Standard -Ccommunications service, giving the sys-tem virtual global coverage.The Standard -C system is capable ofproviding two-way data or message com-munications to or from virtuallyanywhere in the world. Originallydeveloped to meet the needs of maritimecustomers, the small, lightweight, low-cost Standard -C terminals are compactenough to be fitted to any vehicle orvessel, or to be hand -carried. The system
can also be used for vehicle positionreporting, remote monitoring and con-trol, or remote emergency alarmsystems.
TRANSPUTER TRAININGPACKAGEThe world's first fully integratedtransputer training package, retailing at£995, has been launched by Flight Elec-tronics of Ascupart Street, Southamp-ton, SO1 1LU. The system allows a highlevel of transputer literacy to be achievedin a very short time.With support from the SERC (Scienceand Engineering Research Council),Southampton University developed thesystem in conjunction with Flight'straining system specialists.
INSTRUMENT RENTALS OBTAINSBCS APPROVALInstrument Rentals has become the firstrental company in the UK to receiveBritish Calibration Service (BCS) ac-creditation for its calibration service.The company is, therefore, now able tocalibrate a range of instruments in ac-cordance with the NAMAS (NationalNleasurement Accreditation Service)schedule.
58 EE
December 1988
TEST & MEASURING EQUIPMENT
Part 12: Signal Generators (6)
Thandar TG502The Thandar TG502 represents an in-termediate step between the low-cost2 MHz signal sources and the vastlymore expensive synthesized generatorsthat start at around £1500. The price ofthe TG502 is £495.The TG502 is one of a family of three:the TG501 is a basic model, priced at£325, while the TG503 priced at £545,provides pulse generator as well as all theother facilities of the TG502.The TG502 is connected to the mains bya standard IEC socket. The mainsvoltage may be 100-120-220-240 V: selec-tion is by means of interchangeable tapson the mains transformer.
Main generator. The continuously vari-able output frequency is read from a lin-ear/logarithmic scale that covers a rangeof 1000:1 and 10,000:1 respectively. Thefrequency range is specified as 5 mHz to5 MHz, although the review model ex-tended up to 6.3 MHz. The accuracy ofthe vernier control is fairly good, exceptat the mid -point of the scale where thespecified error of ±5% was approached.Only approximate gradations areavailable on the logarithmic scale.Range selection is by seven pushbuttonswitches, covering multiplying coeffi-cients of 1 to 1 million.Symmetry control is available only up to500 kHz since when this facility is oper-ated the output frequency is divided by10.Output level performance is good.Switched attenuators are provided thatgive the standard -20 dB and -40 dBreduction in output amplitude to com-plement the variable control. This per-mits the output levels to be set as low as8 mVpr, into 50 ohms, and up to 20 Vp9e.m.f.Noise levels are low at all output levels.A d.c. offset control is provided whichoperates at the obligatory 50 -ohm out-put.A TTL output is also provided: therise/fall time is about 10 ns.The TG502 offers an impressive range ofoperating modes for an instrument inthis price range, including triggered,gated, manual, and continuous. Thestart/stop phase is variable over twoquadrants. Performance in all these
by Julian Nolan
modes is good, which makes the TG502suitable for use in a wide range of appli-cations.Distortion is fairly good: on the reviewmodel 0.5% up to 95 kHz, increasing to1% at 620 kHz.Sine wave output flatness is good at±0.2 dB up to 500 kHz and ±1 dB to5 MHz.In addition to the three mainwaveforms-sine, triangle and square-a d.c. output is available.
Sweep generator. The sweep section in-corporated in the TG502 should satisfymost users. It offers a wide range offunctions and a good level of versatility.The sweep range extends to 1000:1 or10,000:1 in the linear and logarithmicsweep modes respectively. Both sweepstart and stop frequencies can be set, aswell as the sweep rate, which may bevaried from 20 ms to 120 s. A highersweep rate of, say, 5 ms might have beenuseful for some applications. Sweepsmay be single or continuous: a holdmode is available that stops the sweep atits instanteous value.A marker is also available to halt thesweep for a preset time. This is useful
when the sweep generator is used with anoscilloscope to measure, for instance, afilter response, when a number of pos-itions on the response curve-: requirehighlighting.The generator provides inputs for an ex-ternal sweep reset and hold, and outputsfor sweep output and pen lift for a plot-ter. There is also a sweep input for situ-ations where sweeps conforming to func-tions different from the built-in ramp arerequired.
Construction. As may be expected fromThandar, no compromises have beenmade in the construction of the TG502.External construction is based on a two-piece metal enclosure with steel end -plated. This gives the instrument ajustifiably solid appearance and shouldenable it to be used in a wide range ofenvironmental conditions.Front panel layout is good, alhoughseveral control positions take some get-ting used to.Outputs, such as the marker function,are located at the back of the instru-ment.Although the design of the enclosuredoes not really enable it to be stacked,
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December 198859
Table 17
TECHNICAL SPECIFICATION
Main generatorFrequency range:
Sine wave distortion:
Triangle:
Square wave:
Operating modes:
Inputs:
Trigger input:
Outputs:
Sweep generatorRange:
Controls:
Sweep rate:Marker:
Annunciators:
Inputs:Outputs:
MiscellaneousInput voltage:
Accessories:Dimensions:
Weight:
0.005 Hz to 5 MHz in7 decade ranges:vernier accuracy± 5%.
<0.5% to 50 kHz,<1% to 500 kHz; allharmonics >30 dBbelow fundamental in1 MHz range; flatness=0.2 dB to 500 kHz,=1 dB to 5 MHz.
linearity >99% to500 kHz.
symmetry ± 1% to100 kHz; rise/falltime >45 ns.
continuous, gated andmanual.
sweep sensitivity 0 to4 V for 1000:1 (lin-ear) sweep; max.slew rate 0.1 Vies.
DC to 5 MHz; TTLcompatible; start/stopphase variable ±-907'.
50 ohms; switchedattenuator 0 dB,-20 dB and -40 dB;variable attenuator0 dB to > - 20 dB;peak level 20 Vppe.m.f. or 10 Vpp into50 ohms; DC offsetcontrol ±10 V e.m.f.;TTL output can drive20 loads.
10,000:1 (logarithmic)or 1000:1 (linear).
sweep limits; reset;single sweep; hold;on/off.
20 ms to 120 s.duration variable from
10 ms to 10 s; fre-quency set bu verniercontrol.
reset; hold; end;marker off scale.
sweep reset and hold.sweep and pen lift.
100-120-200-240 V50/60 Hz a.c.
mains lead; manual.300 x 145 x 230 mm(WxHxD)
4.2 kg.
this should not affect the ease of use ofthe instrument.The well -thought-out internal construc-tion is based on two double -sidedfibreglass PCBs. Access to both theseboards is good, which should make anyservicing quite easy. Heat dissipation onthe boards is low.The operating manual is fairly extensiveand includes detailed sections onoperating modes, sweep generator func-
Table 18
Unsatis- Satis- Veryfactory factory Good good Excellent
Dial accuracyDial resolution *External sweep range *Distortion *Frequency range *Output level range *Internal construction *External construction *Overall specification *Ease of use *Manual *Additional features *
tions and a number of applications. Nocircuit diagram or servicing informationis given, but a service manual is availableas an optional extra.
Conclusion. The TG502 is a mid -rangeinstrument providing a good blend oflow cost and performance. Its sweepfacilities are particularly notable as areits triggering options. A higher sweeprate, coupled perhaps to sweepwaveforms other than the ramp, wouldhave been useful for some applications.The sweep eenerator is, however, veryeasy to use.The frequency range of 5 mHz to5 MHz and the TTL output make theTG5502 suitable for use on digital equip-ment. If that is the primary requirement,however, the TG503 should be con-sidered.Construction of the instrument is goodand this, together with its good perfor-make, should make the TG502 ideal foruse in a wide range of applications.
The review model of the TG502 was sup-plied by the makers, Thandar Elec-
tronics Ltd, London Road, St. Ives,HUNTINGDON PE17 4HJ, Telephone(0480) 64646.
Other function generators available inthe Thandar range areTG101 - reviewed in the June 1988 issueof Elektor Electronics; price £110, excl.VAT.TG102 - reviewed in the June 1988 issueof Elektor Electronics; price £160, excl.VAT.TG501 - 5 mHz to 5 MHz; triggeredand gated modes; variable stop/startphase; DC offset; TTL output; distor-tion <0.05% to 50 kHzl RRP £325,excl. VAT.TG503 - similar to TG501 but withadded pulse generator; double pulsemode permits max. frequency of10 MHz; symmetrical positive- ornegative -going outputs with adjustablebaseline; delayed pulse also available;RRP £545, excl. VAT.TG105 pulse generator - 5 MHz to5 MHz, eated and triggered modes;square wave plus complement; TTL andsync outputs; RRP £105, excl. VAT.
60 EE
December 1988
BACKGROUND TO ETROMSMemory chips with large storage capabilities invariably steal the
limelight these days. There are, however, many interesting low-capacity devices available as well. One of these is the
electrically erasable programmable read-only memory - E2PROM.Its low cost, versatility and ease of programming make this device
an ideal component for many applications involving thepermanent storage of, for instance, instrument configuration data.
As an example of the operation and ap-plication of a typical EPROM (orEEPROM), this article discusses the256 -bit Type NMC9306 from NationalSemiconductor. Readers of this maga-zine will recognize this device from theMicrocontroller-driven power supply(Ref. 1), where it is used to for storageand retrieval of voltage and current set-tings associated with 3 user -selectable in-strument configurations.Basically, an E2PROM couples the non-volatily of an EPROM to the flexibilityof a RAM. In this sense, it is functional-ly similar to a RAM with battery back-up, or a zero -power RAM (e.g. the48Z02). Among the advantages of theEPROM discussed here are its low costand simple -to -use serial interface, whichis of particular interest when the deviceis to be incorporated in existing systems.
Features and applicationsAn EPROM is a read-only memory,and can, in principle, only be read from.Its special internal configuration, how-ever, makes it possible to erase the deviceelectrically, and re -load it, during nor-mal operation. This obviates the needfor exposure to ultraviolet light, and theapplication of a high programmingvoltage, required for erasing and pro-gramming a conventional EPROM. TheNMC9306 is fed from a single supplyvoltage, 5 V, and has an on -chip step-upconverter that supplies the programmingvoltage. Each of the sixteen 16 -bitregisters can be erased individually. Animportant difference with respect to aconventional RAM is, however, the timeneeded for loading (=writing to) aregister. In the case of the NNIC9306,this programming cycle takes at least10 ms per register. Also, the number ofwrite operations is limited to about10,000 per register. The maximumguaranteed data retention period is10 years, so that data will need to be`refreshed' at least once during this time,by means of a erase -write cycle.As already noted, the E2PROM is idealfor quasi -permanent storing of equip-ment configuration data. As an example
Component availability note:The NMC9306 is available from Elec-troMail, P.O. Box 33, Corby, NorthantsNN17 9EL. Telephone: (0536) 204555.Stock number: 301-656.
of that application, Philips Test Instru-ments fit a number of their top -gradefrequency meters with an E2PROM thatholds data corresponding to the tem-perature response of the central quartzcrystal built into a temperature -compensated oven. The temperaturecoefficient of each quartz crystal in-tended for use in these instruments is in-dividually recorded as a curve, which isthen digitized and loaded into theEPROM. The microprocessor that con-trols the instrument measures the tem-perature of the oven, loads the relevanttemperature coefficient from a look -uptable, and corrects the central clock fre-quency to ensure minimum deviation.
Practical useAn essential difference between anEPROM and other memory chips is
Dual-ln-Line Package
ICJ. 11E11
Order Number NMC9306NNS Package Number NOSE
Pin Names
CS Chip Select5K Serial Data ClockDI Serial Data InputDO Serial Data OutputVCC Power SupplyGND Ground
880086-10
Fig. 1. Block and connection diagrams of EPROM Type NMC9306.
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December 198861
apparent from the block diagram inFig. 1. Data is sent to, and read from,the EPROM via a serial interface,which not only makes it possible tohouse the chip in an 8 -pin DIL package,but also makes its use independent ofdata- and address -bus structures - theE2PROM is simply a small peripheraldevice.The serial input and output pins (DI andDO) may be controlled by separate serialformats. The serial interface is also usedfor reception, from the host micropro-cessor, of control commands for theE2PROM. These are 9 -bit serialdatawords, in which the start bit isalways logic high. The next 4 bits formthe opcode (see Fig. 2), followed byanother 4 bits that form the register ad-dress.The function of the E2PROM controlcommands can be summarized asfollows:
III Read: data is first loaded into thedata shift -register, and then shifted
out via the serial output DO. The shift -out operation is clocked by the low -to -high transition of the signal applied tothe SK input. A dummy bit (logic 0)precedes the 16 -bit data output string.Only the read instruction causes serialdata to be output via the DO line. Erase/write enable (EWEN): this
command should always precededata erasure or loading operations.IN Erase register: unlike a RAM, an
E2PROM register should be cleared(erased) before loading it with new data. Erase all registers: similar to the
above command, but works on thewhole chip rather than on an individualregister. Write: load data in a previously
cleared register.III Write all registers: the same data is
written to all registers.Erase/write disable: this commandprevents accidental clearing or over-
writing of registers.
Instruction SS Op Code Address Data Conwnents
READ 1 10xx A3A2A1A0 Read register AIA2A1A0
WRITE 1 01xx A3A2A1A0 D15 -DO Write register A3A2A1A0
ERASE 1 Mix A3A2A1A0 Erase register A3A2A1A0
EWEN 1 0011 >Dom Eraselwrite enable
EWDS 1 0000 sada Erasehvrite disable
ERAL 1 0010 =cc Erase all registers
WRAL - 1 0001 moot D15-00 Write all registersNIACEXISCONal hist lostruelforat as stem Noes that ili8o1 any given Instruction ul a- I' and ts retoldas start bit in the lotartace aaquaroo The nest II tits carry ma op Cole anti the Sail address for I al lqaete re9Istire-X Is Cool cars stela.
880086-11
Fig. 2. Instruction set of the NMC9306 16x 16 -bit E2PROM.
CS
O®opeccie re.;.s!,
b: (111XX= laTC1a)
as. _I-C)EDC- real
in.structi.L.r.
Fig. 3. Timing of the E2PROM write cycle.
Two control lines on the E2PROM ar-range the timing. Low -to -high clocktransitions on line SK (serial data clock)control the shifting in and out of dataand commands. The maximum clockfrequency is 250 kHz. Line CS (chip sel-ect) is active high, and enables ordisables all data and command I/O op-erations. It also serves to time theerasure and programming pulses, whichshould have a duration of 10 to 30 ms.After the loading of a clear or writecommand, the relevant cycle starts whenCS goes low. Programming lasts until CS
reverts to logic 1. In the mean time, in-put SK is disabled. After programminghas been completed, CS may remainlogic high to enable loading a new com-mand. When CS is made logic low, theEPROM is switched to the low -powermode. In between commands, theminimum low -time of CS is I its.
H
Reference:1. Microcontroller-driven power supply.
Elektor Electronics May 1988, June1988, September 1988.
NEWSMILLIMETRE WAVEBANDS SETFOR COMMUNICATIONSBOOMBritain plans to take a lead in talks juststarting on the European harmonizationof frequency allocations that will beneeded as a result of the opening of asection of the radio frequency spectrumabove 30 GHz. Experts believe that thecommercial use of this waveband willlead to a communications boom withsuch things as leadless office telephonesand personal pen -sized telephones thatmay be carried in the pocket.Radio frequencies above 30 GHz haveuntil now been little used because of the
high cost of equipment for operation inthis band.
MORE TELECOMMUTERS?A report from the Henley Centre forForecasting, commissioned by BritishTelecom, predicts that the number oftelecommuters-people who travel towork down the telephone line ratherthan by train or car-will soar fromaround two million today to some 14.5million by 1995.Furthermore, the high-tech home of thefuture will be controlled by a telephonecall to operate a cooker, switch. on thecentral heating, and even draw the cur-tains, according to the report.
NEW -TECH COMMUNICATIONSFOR ROUND -THE -WORLD RACEThe 1989 Whitbread round -the -worldyacht race is to be provided with themost sophisticated global communi-cations and information system yet de-vised for such an international event.Using technology currently beingdeveloped at British Telecom'sMartlesham research laboratories,British Telecom International (BTI) willprovide computer graphics that will dis-play the position of the yachts through-out the eight -month long race. The sys-tem will use regularly updated datatransmitted from each yacht so that arange of information and graphic dis-plays will be available to the race organ-ization headquarters in Portsmouth.
62 EE
c:T,b
COMPOSITE TO - TTL ADAPTORFOR MONOCHROME MONITORS
Among the welcome side -effects of the current invasion of IBMPCs and compatibles are the drastic price cuts for high -resolution,12 and 14 inch, TTL-compatible monochrome monitors. The circuit
described here makes it possible to use such a display inconjunction with a computer that has a composite video output
only.
Many owners of popular home com-puters must at some time have been en-vious of IBM PC users, because theseare in a position to look at text andgraphics on a restive, high -resolution,non -glare monitor instead of on a(modified) TV set tuned to channel 36,and barely capable of displaying 80characters per line. Until recently, how-ever, the cost of a TTL monitor was suchthat manufacturers of home computersin the lower price ranges did not evenconsider equipping these with a digitaloutput. The inexpensive adaptor circuitdescribed here should allow manyowners of the first generation of homecomputers to benefit from the advan-tages offered by the TTL-compatiblemonitor.
Circuit descriptionThe circuit shown in Fig. 1 effectivelysplits the CVBS (composite video -blanking -synchronisation) signal ap-plied to the input into three components:horizontal and vertical synchronizationpulses, and video. These three signals arethen converted to digital level to enabledriving the corresponding inputs on theTTL monitor.The low reference level of the CVBSsignal is first set to 0 V by an activeclamping circuit around ICI. Figure 2shows the voltage levels in a CVBSsignal. Note that the amplitude of Usyncis usually about one third of that ofUvideo. The switching threshold of com-parator IC2 is set such that only thesynchronization pulses can cause theopamp output to go low. The compositesync signal is then fed to XOR gate Niand to a two -section R -L -C low-passfilter. Switch SI connected to pin 2 ofNI selects the signal polarity at the H-sync output. The presence there of V -sync pulses has no consequence for theTLL monitor. The V -sync pulses ob-tained after filtering in the low-pass canbe inverted, if necessary, by closing S2.Inversion is probably not necessary formost types of monitor, but users are welladvised to consult the relevant manual incase of doubt.
A fast comparator, based around opampType 733 (IC3) and FETs TilT2, extractsthe video component from the CVBS in-put signal. It should be noted that the at-tainable contrast ratio is mainly deter-mined by the speed of the opamp, sothat the circuit does not work correctly ifIC3 is replaced by a slower type. Thetoggle point of IC3 is set to the averagevideo level by P2. Impedance conversionbetween the opamp and the digital videoinput of the monitor is achieved with TSand Ts, the latter functioning as an ad-justable zener diode.
Construction, setting up andapplicationThe adaptor is constructed on theprinted circuit board shown in Fig. 3.The two inductors are preferably ferrite -
encapsulated radial types from Toko.The completed unit can be installed inthe monitor, which usually has room tospare inside. This has the advantage thatthe adaptor can be fed from the existingpower supply, ensuring correct interfacelevels (check the specification of themonitor in this respect). As shown in thecircuit diagram, the adaptor is uncriticalof the supply voltage level, as long asthis is between 5 and 12 V, and wellregulated.An oscilloscope enables the unit to bealigned quickly. With reference to Figs. 2and 3, measure the levels V2Usyne (x),and thync-F 1/2Uride0 (y), and set thesevoltages as the toggle levels for IC2 (Pi)and IC3 (P2) respectively. Adjust P3 foroptimum picture resolution and stab-ility. When an oscilloscope is notavailable, set P2 and P3 to the centre of
VIDEO
C
0RI7
Cl220,RI
MZE
0
4
BF25613TD
513
tt
TI
RIOM -144.1C4=40300
CA31.73
0 905608
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T5
WA
IC3733
a
505RI4
A A.
LIINI
ICrtHC3
Ct
L2In =1 MI
10714CS
Ts- 70
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3S0Rt5
fl
DAISES
VIDEO
I
A
N O,Si
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0
52
F494
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- .
C26Rom IC 3
OUIC2
0
0
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VERT
S
UB
5-12Vci.
ICI
OIRXIIIS -10
Fig. 1. Circuit diagram of the composite-to-TLL converter.
EE 63
A
Fig. 2. Toggle level for the sync comparator(X) and for the video comparator (Y).
Fig. 3. Oscilloscope display of one line oftext in a monochrome CVBS signal suppliedby a BBC model B computer.
their travel, and turn the wiper of Pt toground. Apply the input signal, andcarefully advance Pt until the picturesynchronizes. Then adjust the other twopresets for optimum picture quality, firstP2 and then P3.The circuit is dimensioned to work withinput video levels between 1 Vpp and4 V9p. The value of R17 may have to beincreased, or the resistor may have toomitted, to ensure correct operationwith home computers whose output levelis lower than 1 V9p. Signal levels ex-ceeding 4 Vpr, can be accomodated bylowering the value of R12. Capacitor C7,finally, also allows some experimentingbecause it may not be required unless avery high resolution monitor (>80characters per line) is being used.
December 1988
Populated printed circuit board.
Fig. 4. Printed circuit board for the adaptor.
Parts list
Resistors (±5%);RI =100KR2;13B;811;81.3= 1K0
R3= 47ORR4;R12=2K2Re =220KR6= 1K5R7 = 2K7
119;Rio = 10KRI:4;915=100RR16= 120RR17= 2208
=50011 preset HP2=2K or 2K5 multiturn presetP3= 50K preset H
Capacitors:Ci =220nC2;Ce=33nC3;Ce = 2n2Cz;C to= 47nC7 =390pCa=4y7; 16 VCa;Cit =100n
ICI;IC2=CA3130IC3=uA733 or LM733IC4 = CD40308
Miscellaneous:LI;L2=10mH radial inductor, e.g. Toko Type
181LY-103 iCirkit stock no. 34-103021.St;S2= miniature SPST switch.PCB Type 880098 (see Readers Services page).
Semiconductors:Dr=1N4148Ti :T2 =BF256B13 ---8F494T4=BFR96S (listed by Bonex Ltd.)TE = BC5608
64 EE
December 1988
GUIDING THOSE WAVESby W.D. Higgins
An increasing number of engineers have to consider processingsignals in the gigahertz frequency range: satellite TV,
information/data systems, point-to-point microwave links, andradar are but a few examples of fields where a basic understand-
ing of the operation of waveguides is required, and where thisbrief 'guide to waveguides' may prove useful as an introduction.
A waveguide is essentially a precision -engineered length of hollow, usually rec-tangular, aluminium, invar, copper orbrass (70/30 and 90/10) tubing thatserves to carry microwave RF signals.Whereas professional -grade coaxialcable is used up to about 3 GHz withconsiderable attenuation, certain typesof waveguide are suitable for carryingRF signals at frequencies of 50 GHz andhigher, at an insertion loss that remainsnegligible even for relatively long runs.Waveguide technology can be treated asa very fine art, but is in principle verysimilar to conventional plumbing. Sincewaveguides and ancillaries such as coup-ling flanges, preformed twists, T -
junctions and coaxial transitions areavailable ready-made in a variety ofsizes, the engineer will have to decide onthe most appropriate practical size of thewaveguide, bearing in mind cost andmachinability. To these factors must beadded the technical considerationwhether or not a particular waveguidesize can be used at the frequency of in-terest. The physical size of a waveguidedetermines thelowest frequency at whichit can be used, i.e., at which it is capableof propagating RF energy in a relativelyloss -free manner. Any type of wave -guide, therefore, has its specific cut-offfrequency, below which attenuation risesrapidly.The dominant propagation mode in awaveguide is referred to as TE10. Thedistribution of the electric and magneticfield in TEto mode is illustrated inFig. 1. The electric field strength is maxi-mum at the centre of long walls of thewaveguide, and decreases sinusoidally tonought towards the short walls. Themagnetic field has a loop -like configura-tion, and is distributed in parallel withthe long wall of the waveguide.To prevent excessive attenuation, theTE10 mode requires a minimum size ofthe internal waveguide width, w, of 0.5A.The previously mentioned cut-off fre-quency therefore corresponds to awavelength, Ac, equal to 2w. Width wshould not exceed ). to prevent the domi-nant mode changing from 1E10 toanother electromagnetic pattern whose
structure causes matching problems atthe input and output of the waveguide.In practice, w is made slightly greaterthan 0.52 because the wavelength of asignal in a waveguide, As, is greater thanthe free -space wavelength, Ao:
Ao-1/1 - (A0/2w)
This equation applies to the TE10 mode,and shows that 2. approaches infinityas w approaches 0.52. In practice, theminimum value of w is chosen between0.6). and 0.952 to prevent components orjoints in the waveguide causing propa-gation discontinuities or electrical
losses. Similarly, to prevent polarizationreversal between the input and output ofthe waveguide, the internal height, h, ischosen lower than 0.452. The maximumfrequency of operation of a waveguide isusually 2fc.
Standard rangeMost manufacturers of precisionwaveguides produce a standard range ofsizes (and materials) that conforms tovarious European and US specifications.European specifications include IEC153(1&2), DIN47302, BS9220, DEF5351and CCTU10-20. US specifications in-clude MIL -W -85C, EIA, RS261-A andJAN -MIL.
Fig. 1. Relative intensity of the electric and magnetic component in TER. mode.
Waveguide size is denoted by a WG num-ber. The most commonly used sizes arein the range WG5 to WG28 - the higherthe WG number, the smaller the wave -guide, and the higher the cut-off fre-quency (remember that this is the lowestfrequency at which the waveguide can beused). Table 1 gives data of a number ofwaveguide sizes.As a rule of thumb, the attenuation of awaveguide increases with length and theWG number. A few examples of typicalattenuation figures are included inTable 1. WG16 is particularly popularamong radio amateurs for use in 3 -cm(X -band) and home-made Ku -band
equipment (satellite TV reception). Ex -military waveguide systems are often of-fered in a variety of configurations atrallies, and by electroific surplus stores.Often, such units come complete withassociated SHF electronic parts, such asGunn -diodes, klystrons, adjustable at-tenuators, mixer diodes and even hornaerials. Waveguide circulators also exist,but are hard to get hold of.
The usual way of joining lengths ofwaveguide is by means of flanges. Theseare slipped over the waveguide and thenbrazed or soldered in place. Excess wave -guide is usually milled or filed away.
Table 1.
WG number Inside dim.Outside dim.w x h (mm)
Attenuation(dB/m1
Frequency range(GHz)
Cut-off frequency(GHz)
Weight(kg!m)
Radio Band
5 195.6x97.8 0.96 to 1.46 0.77
6 165.1 x 82.6 0.00522 1.14 to 1.73 0.91 9.72 L -band
169.2 x 86.67 129.5x64.8 1.45 to 2.2 1.16
8 109.2 x 54.6 1.72 to 2.61 1.37113.3 x 58.7
9A 86.4 x 43.2 2.2 to 3.3 1.7490.4 x 47.2
10 72.2 x 34.0 2.6 to 195 2.08 S -band
76.2 x 38.111A 58.2x29.1 3.3 to 4.9 2.6
12 47.5x22.1 0.0355 3.95 to 5.85 3.15 2.1850.8 x 25.4
13 40.5x 20.2 4.9 to 7.05 3.71 C -band
14 34.8 x 15.8 5.85 to 8.18 4.338.1 x 19.1
15 28.8 x 12.6 7.05 to 10.0 5.331.8 x 15.9
16 22.9 x 10.2 8.2 to 12.4 6.6 X -band25.4 x 12.7
17 19.1 x 9.5 10 to 15 2.9
18 15.8 x 7.9 0.176 12.4 to 18 9.4 0.48
19 12.9 x 6.5 15 to 22 11.6 Ku -band
20 10.7x 4.3 18 to 26.5 1412.7 x 6.4
21 8.6x4.3 22 to 33 17.3 K:-. s -.
22 7.1 x 3.6 26.5 to 40 21.19.1 x 5.6
23 5.7 x 2.8 33 to 50 26.3
--- 4.8 x 2.4 1.06 40 to 60 31.4 0.168
25 3.8x 1.9 50 to 75 39.9 ri1711.03-,::
26 3.1 x 1.6 60 to 90 48.4
27 2.5 x 1.3 75 to 100 59
28 2.0 x 1.0 90 to 140 73.8
EE
December 1988
Great care should be taken to keep theinside of the waveguide free fromresidual solder, as this introduces highlosses. In general, discontinuities smallerthan 0.12 are tolerable, so that it is per-fectly possible to make one's own wave -guide (and even flanges) from availablebrass or aluminium tubing. Waveguidetee -pieces, adjustable matching pieces,cross -couplers, dummy loads, tuneablefilters, coax adaptors, twists and bends,flexible connecting pieces and direc-tional couplers are available for mosttypes of waveguide. Factors to considerwhen joining lengths of waveguide, orinserting connectors in a waveguide sys-
65
Fig. 2. Not a decapitated robot, this, but a4 -port phase shifter for new high -power C -band radars currently under development inthe USA and Sweden. Photograph courtesyof MM Microaare
Fig. 3. WG-16 waveguide input of a low -noise block down converter (LNC) for Ku -band satellite TV reception.
66 EE
December 1988tern, include the frequency range, VSWRof all ports, power division, port -to -portRF isolation, phase balance, powerhandling, polarization and, of course,physical parameters.
Future trendsAs greater use is made of the microwavebands, the demand for waveguides, andwith it SHF research and development, isfound to increase. In the field ofmetallurgy, new alloys may be inventedwith better physical characteristics, to re-duce attenuation, improve machinabili-ty, and allow greater power handling.
N
Addresses of companies handlingwaveguides:
Du-Keren cio Frequency Techniques Cornwallis House Howard Chase Basildon Essex SS14 3BB. Tele-phone: (0268) 293401.Evered P.O. Box 21 LewishamRoad Smethwick Warley WestMidlands B66 2BW. Telephone: (021555) 5885.Flann M.I. Dunmere Road Bod-min Cornwall PL31 2QL. Tele-phone: (0208) 3161.
Fig. 4. A piece of WG16 waveguide fitted with one flange, a small horn aerial, and a home-made two -stage Ga-As FET preamplifier for Ku -band satellite TV reception, fitted on to alength of brass waveguide. Input and output coupling to the waveguide is effected with internalV:). probes.
MM Microwave Ltd. ThorntonRoad Pickering North YorkshireY018 7JB. Telephone: (0751) 76363.
H. Rolett &Co. Ltd. Howie Street London SW11 4AR. Telephone: (01
228) 7872.
EVENTS
IEE Meetings2 Dec. The RDS system-its im-
plementation and use.5 Dec. Frequency spectrum manage-
ment.7 Dec. Sea traffic control-the impact
of electronic technology.8 Dec. Cassini-the mission to survey
Saturn and land on Titan.12 Dec. CD ROM.12 Dec. The future of telecommuni-
cations in the leisure industry.13 Dec. Recent developments in
engineering design concepts.13-14 Dec. Satellites and broad-
casting.15 Dec. Digital signal processing for
VLSI.19 Dec. Digitized speech communi-
cation via mobile radio.Details on these events may be obtainedfrom The Secretary IEE SavoyPlace LONDON WC2R OBL tele-phone 01-240 1871.
The Third Annual Computer and Tech-nology Show organized by SATRO(Science and Technology Regional Or-ganization) will be held at the MusicHall, Aberdeen, on Sunday 11
December. Details from SATRO (DrLesley Glasser) Marischal College University of Aberdeen Broad Street ABERDEEN AB9 lAS Telephone(0224) 273161.
The 1988 Data Acquisition Show will beheld at the National Exhibition Centre,Birmingham, from 29 November to 1
December.Details may be obtained from BushSteadman & Partners Ltd The Hub 9 Emson Close SAFFRON WALDENCB10 IHL Telephone (0799) 26699.
The European Satellite CommunicationsConference will be held at BAFTA, Lon-don, on 1-2 December.The Electronic Messaging Systems Con-ference will be held at the Tara Hotel,London, on 6-8 December.Details of these two events may be ob-tained from Blemheim OnlineBlenheim House Ash Hill Drive PINNER HAS 2AE Telephone 01-8684466.
The European Communications Weekwill be held in Amsterdam from 6 to 9December.Details from RAI Exhibitions, telephone
01-741 4437.
An International TelecommunicationsEquipment Exhibition will be held inHong Kong from 10 to 13 December.Details from ADG Exhibitions, tele-phone (02403) 29406.
EE
December 1988
LOOKING BACK67
Updates, applications and improvements for recently publishedprojects
Stereo limiter(Elektor Electronics January 1988, p.57-59).The operation of this design can be im-proved with a few minor alterations,which have to do mainly with the DCbias of the gain cells in 1C3. To beginwith, C3 and Go are replaced by wirelinks. This upsets the DC bias of A5and A6, however, so that furthermodifications are required. The positive(non -inverting) inputs are taken to pin 6and pin 10 of 10 instead of to ground.Further, R -C networks are fitted acrossRs and R12 to reduce the direct voltagegain to about unity. The R -C networksonly provide negative feedback for directvoltage, and do not, therefore, affect theAC gain. The last modification entailsconnecting an electrolytic capacitor inseries with R6 (R13). The modified cir-cuit diagram of the stereo limiter is givenin Fig. 1.On the printed circuit board, replace C3and CI by wire links. The R -C net-works are soldered direct across R5 andR13. Remove 1C2 from its socket andbend up pins 3 and 5 before re-insertingthe chip. Use short lengths of insulatedwire to connect pins 3 and 5 with the in-dicated pins of 1C3.
HF operation of fluorescenttubesElektor Electronics June 1988, p.
36-43).Control of more than one tube.As stated in the article, the controller is,in principle, suitable for powering onetube only. When two tubes ar connectedin parallel, a problem arises during start-ing. Normally, when one tube is connec-ted, resonance will occur at some pointwhen the VCO frequency swings from80 kHz to 30 kHz, and it is at this pointthat the tube is started. With two tubesin parallel, one will always start first,causing damping of the resonance circuitand making it impossible for the otherto start. Simultaneous starting of thetubes is possible, but a matter of purechance. Moreover, the current control
1040.Loa
pin 6IC3
F., C1
CI DI1.2
07V (D +1N4148
ciliao11IC 1 IC2
220n
C3 s-
CSF H F4C)
C2S
I ..-1*
HIC 3
11E572
CS
22p
FOP:112 22
5-SG
CIO: :Orr
L C2..5 =120
*144 teal
pin 10IC3
47z
R14
L
Cu
A1....A41-= IC 1 = TL074; OP470AS, AS = IC 2 = LF353; TL072
655112-17
Fig. 1. Modified circuit diagram of the stereo limiter.
68 EEDecember 1988
circuit and power output stage of thetube controller are not capable of hand-ling double the current.Series connection of fluorescent tubesoffers better prospectives, but worksonly with relatively low -power tubes ofup to 2x 20 W. The connection diagramis shown in Fig. 2. Capacitor CI isomitted from the board, and 'split up' inCia and Clb. During starting, Cia andClb ensure a current flow through alltube filaments, and at the same timeprovide equal distribution of the startvoltage. Since CI. and Clb are connectedin series, their value should be doublethat of CI (see Table 1 in the article) togive the correct equivalent capacitance.Two series -connected fluorescent tubesof 20 W each are now equivalent to asingle 40 W tube.Following the simultaneous ignition ofthe tubes, these can be dimmed as if theywere one tube. It will be noted, however,that the point of minimum brightness(set with P2) is slightly less favourablethan with one tube. This is so because ata certain point one tube will go out, butits parallel capacitor will tend to keep theother on. This effect can be explained bythe highly irregular impedance charac-teristic of the fluorescent tube, whichbehaves like a current -dependent resist-ance. Series connection of fluorescenttubes is best done with types of the samemanufacturer, wattage and age.There is no way to go round building therequired number of HP controllerboards when connecting, for instance,two tubes of more than 30 W, or 4 tubesof 20 W. Fortunately, these can still bedimmed simultaneously with a centralcontrol as shown in Fig. 3. In this set-up,it is important that the mains connec-tions to the controller boards are inphase.
Cable length between controller andtube.A cable of several metres length is, inprinciple, no problem as long as itscapacitance is low relative to that of CI.In practice, this means that cables fromKi should not be allowed to run tooclose to those from K2. It is stillstrongly recommended to fit the con-troller board as close as possible to thetube, with adequate ventilation, becausethe use of a relatively high switching fre-quency on a long cable is bound to in-troduce a strong electromagnetic fieldwhich causes radio and TV interference.The use of shielded wire, however, is notrecommended because it increases thecapacitance to ground.
Oscillator stability.The bias current of zener diode D12 inthe control circuit is relatively low to re-duce the current consumption of thecontrol circuit. In some cases, the biascurrent is too low, however, and gives riseto instability of the zener voltage. Thisresults in temperature dependence of the
L1Nemism,
1m8H
see table
K2 TL1
1W
C1a C1b1111110n
1500VCl. x
II-
TL1; TL2 = 2 x fluorescent tube 20W,or 2 x TLD tube 18W.
TL2
1500V
K1
220n400V
C3
0n400V
885112 - 11
Fig. 2. One controller board connected to tlAo fluorescent tubes.
TL1
6111... _
°. i -f-4:4-.11101---- -i Trll? - a
il ..
. .
I ' ; 61.7.'
e. ..,,,. tt i M 01144aLc - as -,..Vra ..
TL2
885112-12
Fig. 3. Showing how controller boards can share the intensity control potentiometer.
oscillator start frequency. To ensure A timer/controller for aquarium lightingreliable start behaviour of the circuit, it is currently under development.is recommended to redimension a num-ber of components:R16 is changed from 6K8 to 2K7;1212 is changed from 39K to 15K;C7 is changed froni 100 µF to ,220 µF.
EE
December 1988
STAN WILLETTSDEPT 33, 37, HIGH STREET, WEST BROMWICH,
WEST MIDLANDS B70 6PBTel. 021-553 0186 559 1437 (night)
"REDIFFUSION"TRANSLATOR NO. 8470388 -way "Preomat"-T.V. tuning of band I, III& U.H.F. with AVC (less VHF tuner), Mainspower supply 240V in plastic cabinet14 x 71/2 x 31/2 inches. This translator maybe used directly or modified to convertwired TV to normal use with MONITOR (iVP -P) TV sound, Tuner, (HI-FI), with anyVGR. The Translators are guaranteed inperfect working order condition "Al"£4.99 P&P £3.00, Circuit & Modificationinstructions £1.00 extra.
GRUNDIG 1NFRA-REDREMOTE -CONTROL VIF-KI(13 function).Consists of Transmitter TPV355 & ReceiverVIF-K1 (suitable for use with GRUNDIG 2x 4 Super & Stereo VIDEOS). These unitsare brand new & boxed complete with bat-teries £4.99 P&P £2.00, VIF-E1 Receiveronly 10 for £9.99 P&P £4.00.Circuit diagram 75 p.
VIDEO HEAD CLEANERBrand new with full instructions £1.99VHS or BETA P&P £1.00.
V2000 VIDEO TAPES"MEMOREX" brand new & boxed VCC360 £6.99 VCC480 £7.99 P&P £1.00.
"GRANADA" REDIFFUSION20 inch colour televisions ormonitors; perfect workingorder; complete with translator£29.00 (callers only).
"VIDEOLAB" V H S VIDEOTAPES E180 PREMIUM QUALITY which werecommend & guarantee one for one ex-change £1.99 P&P £1.00.
CB CONVERTER40 CHANNEL, works in conjunc-tion with A/M 12 volt car radio, brand new& boxed £2.50 P&P £1.00.
THERMOMETERCOMPASS CLOCK (digital),brand new and boxed. £2.50 P&P 75p.
HARRY MOSS165 p.s.i., AIR COMPRESSOR12 V D.C. plugs into cigarlighters; inflates tyres,beachballs, footballs, airbeds,dinghies. PU, PS average Tyre in5 minutes, four -reading pressureguage, 12 ft cord. Brand new &boxed £14.99 P&P £3.00
VIDEO CAMERAEXTENSIONLEAD plug to socket, allcontacts connected 9mmcable £19.95 P&P £2.00
ELECTRONIC AUDIOCASSETTEDEMAGNETIZER,electronic circuit, LED indi-cator. Brand new £7.99 P&P75p.
PLEASE NOTE WE ARE INTERESTED INPUCHASING ALL TYPES OR EQUIPMENT,ANY QUANTITY.
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