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END OF JANUARY,1980)

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Circle No. 2 on Reader Service Card.

Vol. 4, No. 1JANUARY 1980

ISSN 0703-8984Editor

GRAHAM WIDEMAN BAScAssistant Editor

JOHN VAN LIERDE

ADVERTISINGAdvertising Manager

MARK CZERWINSKI BAScAdvertising Services

CHERYL MAYAdvertising Representatives

JIM O'BRIENEastern Canada JEAN SEGUIN &

ASSOCIATES INC. 601 Cote Vertu,St. Laurent, Quebec H4L 1X8.

Telephone (514) 748-6561.

Subscription DepartmentBEBE LALL

Accounts DepartmentSENGA HARRISONLayout and Assembly

SARAH -JANE NEWMANContributing Editors

WALLACE PARSONS (Audio)BILL JOHNSON (Amateur Radio)

JOHN GARNER (ShortWave Listening)DICK CARTWRIGHT (Servicing )

STEVE RIMMER (Video)EDITORIAL AND ADVERTISING

OFFICESUnit 6, 25 Overlea Boulevard,

Toronto, Ontario, M4H 1B1Telephone (416) 423-3262

Published by Electronics TodayInternational (Canada) Ltd.

Printed by Livingstone Printing LtdDelta Web Graphics

News Stand DistributionMaster Media, Oakville.

COPYRIGHTAll material is subject to worldwidecopyright protection. All reasonablecare is taken to ensure the accuracy

of the information.All ETI PCB Patterns are copyright .No company may sell boards to our

designs without our permission.

INTERNATIONAL EDITIONSElectronics Today International,

145 Charing Cross Road,London WC2H 8DEE, UK.

Electronics Today InternationalRyrie House, 15 Boundary St.,

Rushcutters Bay, Sydney, Australia.Managing Editor Collyn Rivers.

Acting Editor Roger HarrisonE l rad

Kommanditgesellschaft, BissendorferStrasse 8, 3000 Hannover 61 Germany

Editor Udo Wittig

Postal InformationSecond Class Mail registration number3955. Return postage guaranteed. Postoffice returns to Unit 6, 25 Overlea

Blvd., Toronto, Ontario. M4H 181

electronics todayinternational

INCORPORATING ELECTRONIC WORKSHOP

PROJECTSGUITAR EFFECTS UNIT 15Wild new sound to hug your neighbours with.SERIES 4000 STEREO AMPLIFIER 18Final details on this high quality amp.LOGIC PROBE 25Cheap 'n easy way to debug digital circuitry.

FEATURES

LM 10-APPLICATIONS 30Eye opening uses for this new device.PRACTICAL GUIDE TO TRIAC'S PART II 38This month Collyn Rivers talks about phase control.A HISTORY OF CAR IGNITION 55Those stories you hear about gerbils and treadmills just ain't true.HAMS AT MISSISSAUGA MADNESS 43This months QRM takes a look at hams and the Mississauga derailment.

NEWS &COLUMNSNEWS DIGEST 4AUDIO TODAY 11Wally Parsons casts a weary eye on the future decade.

SERVICE NEWS 48Dick Cartwright and Bill White talk about the future of the service industry.WHAT'S ON 52This month Steve Rimmer has some hints on buying TV cameras.

TEACHER'S TOPICS 66Graham Wideman looks at a useful digital learning kit.

LISTENING TO THE DARK CONTINENT 68Join John Garner in a tour of Africa's many radio services.THE FUN OF ELECTRONICS 70Electronical laffs by Paul Geiger.

INFO & MISCELLANEOUSNext Month in ETI 65 Babani Electronic Books 60More Circuits 28 Feedback 61Tower's 35 Sams Books 62Binders 36 Classifieds 71ETI T -Shirts 37 Special Book Offers 72Tech Tips 46 Project File 73Subscriptions 58 General Reader Info 74Reader Service Card 58 Advertisers Index 74TAB Books 59THIS MONTHS COVER . An an(ineptitude) on the bass guitar. Aon page 15.

onymous ETI staff member demonstrates his virtuosityctually, you'd do better to look at our Fuzz/Struzz Box

ETI CANADA-JANUARY 1980

NEWS DIGESTFun Organ Kit

Automatic chords and rhythms,alternating and walking bass, harmonicmemory, multiple arpeggios, and manyother space-age musical effects iden-tify the new Schober Showman Auto-matic Electronic Organ as the first ofthe modern "fun" organs in kit form.

Ranking with the most elaborate ofthis type of home instrument, designedto permit players with little or nomusical training to produce highlyvaried and complicated musical effects,the Schober Showman is reported to

cost only about half as much ascomparable instruments. The kitcontains every needed part, plusnontechnical step-by-step instructionsfor both building and playing. Assem-bly time is estimated at about 30 hours.

The Showman contains two separatekeyboards. The upper carries melody(and right-hand harmony if the playerwishes), while the lower controlsharmony, automaticaly or manually.Three pedals modify one -finger -selected automatic chords to produce atotal of 60 different harmonies. Fivemelody voices, including a wah-wahinstrument, can be used alone or mixed.Delayed, regular, and wah-wah vibra-tos are provided.

Eight different automatic rhythmicpatterns (which can be mixed) employfive realistic rhythm instrument sounds.

Tempo is fully controllable, and aspecial extra slow "practice" speedmakes learning easy. Volumes ofrhythm, bass (plucked -string or organ -pedal type), and harmony (steady orrhythmic), and melody are all indepen-dently controllable. Because of theautomatic features, a one -finger playercan actually produce more simul-taneous rhythm, bass, accompani-ment, and solo music than an accom-

Telephone Telemetry

A recently introduced telemetrysystem makes remote readout oftemperature, pressure, level, power orany process variable easily availableover a power or telephone line.

The RFL 64B TMX features accuracyof better than .5%. Utilizing full scalefrequencies of less than 25 Hz, it readilymates with RFL's frequency shifttransmitters, enabling a large numberof signals to be carried on a singlecommunication link. Optionaly avail-able features include; built in calibra-tion, voltage or current input, and signalloss alarm.

plished musician could on a standardorgan.

The Showman console is genuinewalnut veneer and solids. Just asassembling the electronics requires noprior electrical knowledge, consoleassembly and finishing employ techni-ques which demand no woodworkingexperience.

The Schober Showman AutomaticElectronic Organ Kit, priced at $650 US(bench include), is available from TheSchober Organ Corporation, 43 West61st Street, New York NY 10023.

For further information contactDetfol, 94 Claude St., Arnprior ONT.K7S 2H5.

Update On AnalogueFor those interested in ADC, DAC

and other analogue functions, AnalogDevices offers their free house publica-tion, Analog Dialogue. Volume 13, No.2includes application articles on veryhigh speed data acquisition, statisticsmethods using RMS to DC, checkingA/D converter linearity, a 300kHzcontinuous 12 -bit conversion systemand high -resolution DT measurement.Product descriptions include V/Iconverters for process control, a 14 -bitsample/hold amplifier, CMOS swit-ches, three new power supplies, andseveral data converters.

Write to Tracan Electronics Corp.,1200 Aerowood Drive, Unit No. 46,Mississauga, Ontario L4W 2S7.

4 ETI CANADA-JANUARY 1980

Canada, Sink or Swim?"Canada's intense interest today in

research and development is a reflec-tion of the profound economic malaiseaffecting all advanced western indus-trial societies. The developing reces-sion is but one aspect of the currenteconomic crisis and affects, over thelong term, employment, inflation,competitiveness, the strength of ourcurrencies, and the material well-beingof western nations."

Thus the backdrop for his addresswas put in place by Frank Price, VicePresident R & D of GSW Limited, at theannual conference of the Electrical andElectronic Manufacturers Association(EEMAC), in Ottawa last November.

Mr. Price noted that Lenin, fifty yearsago, pointed out an "inherent contra-diction of capitalism" that is still widelymisunderstood today. Lenin had saidthat "The Capitalistic economy plantsthe seeds of its own destruction in that itdiffuses technology and industry ... Itraises up against itself foreign competi-tors which have lower wages andstandards of living, and can outperformit in world markets."

In his address, he described how, inthe first half of this century, US industrygained leadership in many areas, withUS multi -nationals growing into newmarkets around the world and transfer-ring management, capital and techno-logy into these new areas of oppor-tunity.

"In the postwar years the US govern-ment has supplemented and fed thisprocess by pouring research anddevelopment funds into industry,through large military and spaceprograms.

"The consequences are apparent.The U.S., by 1970 had already penetrat-ed the economies of other countriesstrongly - to 80% of GNP in Switzer-land, 5% in several other countries, andjust over 1% in Japan."

Those western economies whostudied this performance after WorldWar II drew the obvious lesson for theirown reconstruction policies, Mr. Pricesaid. Their prime task was to achievetechnological excellence, specializa-tion and marketing strength. Mostimportantly, they had to build theircompetitive positions in world markets,as the linch-pin of economic progress.

He described the government -indus-try cooperation in European countries,and the concerted national endeavourof Japan, which was underwritten by a

large and loyal domestic market.Japanese knowledge -based industr esexpanded rapidly, and indigenousbasic research was accelerated.

Because of these and similar initia-tives over the last ten years, the hithe -tounchallenged position of US industry is

coming under siege. In addition toJapan, other powerful trading competi-tors are emerging. The Third World isnow beginning o emulate the Japan-ese model, and the newly industriali-zing countries are developing intorecognizeable trading threats.

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+to original owner when used with recommended Dower supply.ILP MODULES ARE AVAILABLE IN: BRIDGEPORT, Noya Scotia: F. Rhodenizer.CORNER BROOK, Newfoundland: Electronic Systems. KINGSTON, Ontario: KingstonElectronics. KITCHENER, Ontario: Orlon Electronics. LONDON, Ontario: BucklandCompany. MISSISSAUGA: Atwater Electronics. MONTREAL: Addison TV Parts.OTTAWA: Kris Electronics. PENTICTON, B.C: Lakeland Electronics. QUEBEC CITY: CiteElectronique. TORONTO: Dominion Radio, General Electronics Gladstone Electronics.

Write or call for yournearest distributor! audi ex ELECTRONICS 171.6 Avenue Rd., Suite 8,

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ETI CANADA-JANUARY 1980Circle No. 8 on Peader Service Card.

5

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* 3" High Brilliance CRT* Fully Automatic Triggering* Built-in Calibration Source* Trace Rotator* 2mV Vertical Sensitivity* Operating Modes CH -A, CH -B, Dual, Add/Sub

Chop, and X -YWEIGHT: 13.5 lbs.OPTIONAL ACCESSORIES: Combination 1:1 and10:1 switchable probes(compensated). Priced at$39.00 F.S.T. included.

Vinyl carrying case for Model 65310 only, pricedat $62.00 F.S.T. included.

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The New METERMASTER Model 65610 scopeemploys an extremely bright 5" rectangular CRTwith internal graticule. External DC operationpermits floating measurements. Take a look at thefeatures this scope has to offer:

* Operates from 2 power sources:1) 120VAC line2) 11 - 5 to 30 VDC

* Frequency Response 15MHz(-3dB)* Fully Automatic. Triggering* Built-in Calibration Source* Trace Rotates* HF Rejection* 5mV Vertical Sensitivity* Operating Modes CH -A, CH -B, Dual, Add/Sub

Chop, X -Y, and Z modulation.WEIGHT: 16 lbs.OPTIONAL ACCESSORIES: Combination 1:1 and10:1 switchable probes(compensated) Priced at$39.00 F.S.T. included.

Call one of our offices (below) for a no obligation, free of charge evaluation.

MetermasterR.H. NICHOLS

IN Toronto (416) 661-3190 Montreal (514) 337-0425 Edmonton (403) 432-77465 Ottawa (613) 238-7007 Circle No. 17 on Reader Service Card.

NEWS DIGEST

Intel Math ProcessorsA microcomputer using software

programs to perform certain mathe-matical routines, such as floating pointoperation, may not be fast enough forcertain applications. Special integratedcircuits designed exclusively to per-form math operations can improve amicrocomputer system's performancesignificantly by carrying out computa-tions in parallel with the main pro-cessor. Intel is offering two such chips,the 8232 and 8231 arithmetic process-ing units.

Designed to improve a system'sperformance in applications such asindustrial control, numerical control,scientific calculations, graphics, andpattern generation, Intel's two chipscan improve calculation speed by 10 to100 times over a microprocessorexecuting software routines.

Both math processor chips contain a16 -bit arithmetic logic unit, a micro -programmed algorithm controller, an8 -by -16 operand stack, a 10 -levelworking register stack, command andcontrol registers, and a control read-only memory. All transfers (includingoperand, results, status and commandinformation) take place over an 8 -bit

Operandspushed onto an internal stack andcommands are issued for performing

OSI Superboard ClubOwners of OSI CI P and Superboards,

UNITE. Get updated information onuse of your computer in a newsletter tobe published every two months.

It will contain programs, ideas,technical data, hints and suggestionssubmitted by participating members.

Send a self-addressed businessenvelope and $1.00 for further informa-tion to Superboard Club, Box 55,Agincourt, Ontario M1S 3B4.

Expose YourselfNews digest is a regular feature of ETIMagazine. Manufacturers, dealers,clubs and government agencies areinvited to submit news releases forpossible inclusion. Submissions, orquestions about material, should besent to: News Digest, c/o ETI MagazineUnit 6, 25 Overlea Blvd., Toronto,Ontario, M4H 1B1.

Audio products news will be directedto Audio Today's product department,and similarly Shortwave news willappear in Shortwave World. Sorry,submissions cannot be returned.

5

= Mc

the required operations on the data inthe stack. Following the operation,results data are also located in thestack.

The new integrated circuits will beavailable in sample quantities as of thefourth quarter of 1979; productionquantities are scheduled for the thirdquarter of 1980. Pricing for each is $175in quantities of 100 or more and $195 insingle quantities.

Calendar DateCommunications engineers and

scientists will gather in Seattle this Juneto talk about the latest developments inlight guide communications, homedata terminals and a host of other ideasthat are revolutionizing the way wecommunicate.

The forum is the InternationalCommunications Conference for 1980(ICC '80), and is sponsored by theCommunications Society and othermembers of the Institute of Electricaland Electronics Engineers.

ICC '80 is expected to draw more thana thousand engineers and scientistsfrom more than 20 nations. Many willpresent technical papers outlining thelatest advances in communicationstechnology during some 50conferencesessions scheduled during the meet-ing.

Another attraction will be exhibits oflatest communications hardware andtest equipment.

The conference will be held June 8 toJune 11 at Seattle's Red Lion Motor Inn.

For more information, write toDouglas L. Peck, 393 University Ave.,19th floor, Toronto, Ont. M5G 1W9.

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ALBERTA - Parr Industrial Electronics. B.C. -

Rendell - Paret (Vancouver). GUELPH - NeutronElectronics. HAMILTON - Canadian Admiral.KINGSTON - Kingston Electronics. KITCHENER- Orion Electronics. LONDON - BucklandCompany, Provincial Electronics. MONTREAL -Addison TV, Mícrotron Electronique,Visiontronique Ltd. MISSISSAUGA - AtwaterElectronics. OTTAWA - Kris Electronics, WackidRadio. QUEBEC CITY - Cite Electronique. ST.JEAN, P.Q. - Niagara Electronics. SUDBURY -Sonic Northern. TORONTO - Duncan Instruments,General Electronics, Dominion Radio, GladstoneElectronics, Radio Trade Supply. WATERLOO -Waterloo Electronics. WINDSOR - LighthouseElectronics.

1736 Avenue Rd., Suite b ,ELECTRONICS Toronto, Ont. (416)787-7367

ETI CANADA-JANUARY 1980Circle No. 7 on Reader Service Card.

7

anaOruality Kits

Project *23

Colar OrganThe Jana Color Organ is an ideal project for the experimenter who is a musician or a serious audiophile. This

project is a three channel color organ with a capacity of 200 watts per channel.* It comes complete with the PC boardand instructions and its high power capability makes it ideal for all kinds of lighting effects, either with spotlights orback -lit lucite panels.

Remember, Jana projects come complete with electronic components of the exact value, so there's no need tosubstitute or hunt for specific capacitors, transistors or IC's.

Pick up a Jana Color Organ kit at your nearest Jana dealer today and while you're there, check out the otherJana Quality Kits.

1. Automatic Headlight Reminder 10. Fish Caller 22.2. Battery Operated Fluorescent 11. Hi Power 12V DC Flasher 23.

Light Kit 12. Photo Electric Night Light 24.3. Bug Shoo 15. 0-24V Power Supply 25.4. Code Oscillator 16. Single Channel Color Organ 26.5. Crystal Radio 17. Electronic Siren 27.7. Curiosity Box II 18. Shimmer Strobe Light 28.8. Dally Lighter 19. Tone Generator 29.9. Decision Maker 20. 5 Transistor 1 Watt Amplifier

*Optional circuit to increase wattage capability to 1,000 watts per channelis shown in the instructions.

Xenon StrobeLJ 12016A Color OrganLoudmouth SirenRoulette WheelElectronic Skeet GameElectronic DiceSuper RouletteFM Mini Broadcaster

JOMIOndustrial Electronics

Circle No. 18 on Reader Service Card.1777 Ellice Ave., Winnipeg, Man. R3H OW5

Bush(ing) Fever!A new Heyco Labkit including 240

various sizes and types of terminalbushings is now available from CordsCanada Ltd.

The bushings are inexpensive,insulated receptacles for easy connec-tion and disconnection of wires throughpanels or housings.

The units are nylon housings thatrequire fingertip pressure to snap -lockinto 1/2", 11/16" and 7/8" diametermounting holes. They have one,two orthree flat male terminals that mate witheither 3/16" or 1/4" female quick -connect connectors.

The kit is the most recent addition tothe Heyco line of Labkits. There are alsofive other Labkits which contain nylonstrain relief bushings, insulated bush -

A Counter You CanCount On

After more than 6 months of fieldtesting, Sonotek Ltd. of Mississauga,Ontario released a new, multipurpose,six digit counter. Armed with practi-cally each and every feature thatcompetition claims to have, the newDRT6000 series complements theSonotek DRT3000/4000 family of 312and 41/2 digit process indicators.

Based on advanced LSI technology,the counters lend themselves toapplications in pulse oreventcounting,totalizing and batch control in up ordown count modes, precision time-keeping or frequency measurements.Noise immunity, a characteristic of allDRT indicators, makes them suitablefor industrial environments. Sensitivedifferential inputs with good commonmode rejection allow clean reception oflow level signals over long lengths oftwisted pair or coaxial cable. Singleended, either input will accept directlyTTL or CMOS logic signals -one inputwill trigger on leading edges, the otheron trailing edges of the input waveform.

Digits are bright 10 mm (0.4") LED's,case is black aluminum, designed to fit

NEWS DIGEST

ings, hole plugs and cable clamps.Complete information on the entire

line of Heyco Labkits can be obtainedfrom Cords Canada Ltd., 220 BowieAve., Toronto, Ontario. M6E 2R8.

the standard DIN/NEMA panel cutoutof 92 x 45 mm (3.62 x 1.77"). Variety ofcontrol inputs, optional digital outputsand inputs, companion thumbwheelunits and accessories are available.

For more information please contactBob Morgan Sonotek Limited, 2410-5Dunwin Drive, Mississauga, OntarioL5L 1J9.

Case CatHammond Manufacturing now offers

a new small case catalogue, designatedno 9C-9. It features all of Hammond'ssmall utility cases as well as hardwareaccessories. Other Hammond catalo-gues include, PacTec Electronic En-closures, Plastic And Metal DiecastBoxes and Desk Top Consoles.

Available free from authorized distri-butors or Hammond Manufacturing,397 Edinburgh Rd., Guelph, OntarioN1H 1E5.

S 100 MainframeCalifornia Computer Systems today

announced its new S-100 mainframe, a12 -slot, actively -terminated devicedesigned to give system builders apowerful tool in a small package.

The S-100 Maniframe, measuringonly 115/8 inches high, 7 inches wideand 18 inches deep, comes completewith a fan and a circuit breaker. Itsupports output voltages of + 8VDC at20 amps and + 16VDC at 4 amps.

The GCS S-100 is available for$399.95, assembled and tested, fromCalifornia Computer Systems, 309Laurelwood Dr., Santa Clara, CA95050.

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Just arrived! ACE AUDIO SUBWOOFERCROSSOVER KIT. 100 Hz. 18 db/octave. Model 5000K. Only $141.00NEW GLADSTONE STORE now openat 2936 EGLINTON AVE.E., Scarbor-ough, Ont. Telephone 438-3999.

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w..0MAIL ORDER ADDRESS andMAIN STORE:1736 Avenue Rd.,Toronto, Ont.. M5M 3Y7Phone order line: (416)787 1448.Use your Chargex Visa or Mastercharge.Ont. residents add 7% P.S.T.Both locations open Tues-Sat 9:30-6,till 9 Thurs and FrI.


ETI CANADA -JANUARY 1980 9

NEWS DIGESTPolice Radar: Serious Problems

RIGHT AFTER finishing last month'sextensive report on Police Radar SpeedMeters, we were excited to find outabout certain other studies done onthese units. The US National Bureauof Standards has been evaluating unitsvery carefully since 1978. Great interestwas focussed on their studies when inMay a judge in Florida disallowed suchradar as "prima facie" evidence ofspeeding.

Major complaints with the sets testedby NBS were:

Radar antenna aimed at control boxreads the display multiplex frequency.

Erroneous readings under highvoltage lines.

Interference from neon and mercuryvapour highway lights.

Travelling under an underpassconfuses moving radars.

Interference from car's alternator,blower fan, and tranceivers.

Interference from nearby high -powerairport and other radars.

NHTSAThe US Department of Transporta-

tion's National Highway Traffic andSafety Administration hopes to use thefinal NBS report to develop a list of"qualified products" to guide policeforces in the market for such devices.

CONFERENCE

In October members of the abovegroups, and representatives of policeagencies and other experts gathered fora conference at NorthwesternUniversity's Traffic Institute (EvanstonIll.). The major criticisms revolvedaround the lack of documentation andoperator instruction, either providedby the manufacturer, or required by thelaw enforcement agencies. The feelingappeared to be that the newer sets wereso seemingly easy to operate as to allowanyone to come up with some kind ofa reading, while not requiring theoperator to use the set with the carefuljudgement required to obtain and inter-pret a useful measurement. Even the old"analog" (needle -meter readout) modelswere said to be more satisfactory in thisrespect. It was suggested that a graphicchart recorder ouput would be moreuseful in providing solid evidence forcourt purposes. Even an audio output ofthe demodulated returning radar signal

Here's how "moving radar" CAN be fooled .. .

POLICE

--60mph

50mph4 YOU

BIG TRUCK

40mph

A: Supposed to work out the speed of the cruiserinstead sees reflected signal from big truck, worksB: Works out your speed relative to cruiser as 110mResult: calculates your road speed to be 110 - 20 =

would be of some use to the trainedoperator in overcoming some presentambiguities. (The Tribar MDR -1 whichwe reported on last month has such anoutput.)

Other items under attack were theauto -lock feature (some forces reporteddisconnecting theirs, on the basis thatthis feature made the instrument tooeasy to misuse), and the wide beam -width of some models which was notadequately indicated in the antenna"sights", nor accounted for byoperators.

FUZZBUSTER'S SMITHA prominent speaker at the

conference was Dale Smith, designerand president of Fuzzbuster the famousradar detector. He is regarded as a radar"expert" and has given seminars beforeseveral courts on radar theory. Amongother interesting comments, he says:"An officer who cannot describe howa unit works should not be using radar."

So next time you get a speedingticket find out what kind of equipmentthe officer was using, and prepare toask him some technical questions incourt. Like what's the effective beamwidth, and what does this mean in termsof lane widths at a certain distance(make sure you do YOUR math right!).

Good luck ...

from reflected signal from road,out patrol speed to be 20mph.

ph.90mph! Gotcha.

Memory BookA 440 -page databook on "COS/MOS

Memories, Microprocessors, and Sup-port Systems," SSD-260, can now beobtained from RCA Solid State Divi-sion.

The new databook includes technicaldata, application notes, classificationcharts, cross-reference information,handling information, and orderinginformation on (1) the CDP1800 seriesof COSMAC microprocessors andassociated memory and peripheralcircuits, (2) the MWS5000 and CD4000series of general-purpose memories,(3) the CDP18S600 series of COSMACmicroboard computer systems, and (4)the CDP18S000 series of COSMACmicroprocessor development systems.The data combine definitive ratings,electrical characteristics, dimensionaloutlines and user information.

Copies of SSD-260 may be orderedfrom RCA Solid State distributors or bysending checks, money orders orpurchase orders to RCA Solid StateDivision, Box 3200, Somerville, NJ08876. Thesuggested U.S. retail price is$7.00 per copy.

Other databooks in the series includeSSD-220B, Power Devices (transistors,RF devices, thyristors, rectifiers andhigh -reliability power devices); SSD-240A, Linear Integrated Circuits (in-dustrial and consumer bipolar, MOS,BiMOS and I2L ICs), and SSD-250A,COS/MOS Integrated Circuits (A -series, B -series, special function andtimekeeping ICs).


Audio Today

AN EXAMINATION of the humancondition might suggest that life is justone great big time warp.

Except on those occasions whensomeone is assassinated, or theIranians occupy the U.S. embassy,most people seem to devote moreenergy to either dwelling on the pastorcontemplating the future, but very littleto contemplating the present. Perhapsthis accounts for the existence ofnostalgia; the past is yesterday'spresent, and we were too busycontemplating the past and future toconsider it when it was contemporary.Moreover, it's easier to wear rosecoloured glasses when contemplatingthe past.

Somehow, every once in a while thepast and present seem too horrible tocontemplate, so we indulge in flights offantasy towards the future. Realizingthat the future is probably no betterthan the past, we try to colour it.Prophets and soothsayers have alwaysfigured prominently in the world'sreligions, fortune telling has been asdifficult for authorities to eliminate asprostitution and gambling.

Meanwhile, the beginning of a newyear, new decade, new century, or newmillenium seems to be regarded withsome kind of magical awe. As if a datecould actually be instrumental incontrolling man's affairs. Ordinary folkare not privy to the secrets of the future,of course, so they turn to pundits, apundit being anyone who can scribblesome nonsense via a typewriter and getit published, or babble away infrontof acamera and/or microphone and get hismumbled musings over the air. We arean infallible lot, it sez here, and after all,if it were not gospel it wouldn't getprinted, right here in black and white,right?ETI CANADA-JANUARY 1980

AudioTodayDevelopments in audio reviewed by Wally Parsons

Editors, being a gullible lot, prone toaccepting the propaganda we expertswrite for them, and fond of requestingfor a look at the future every new year.Asking a Cassandra like the professorhere for a rosy forecast is like askingJack the Ripper to perform open heartsurgery.

Consequently, after consulting thestars, sheep entrails, Tarot cards, acrystal ball, and, of course, Gaylord, Ishall now proceed to say some sooths.

UNSOOTHING SOOTHForsooth, it would appear as if the

coming decade will indeed be one ofmarvels undreamed of, Horatio. Superfi discs, digital this, digital that, newbreakthroughs (did you know that,according to their recent TV commer-cials, Pioneer has found a way toimprove bass performace? They do itby using a DC power supply. Willwonders never cease!), you name it.

This is all very fine, except for onevery large fly in the ointment: theworld's headlong dash to economicdepression will not ease up barring amajor war. This means businessretrenchment. And the first thing to gois research. More effort will go intorefining existing technology anddressing it up as new. The last time sucha situation existed was in the earlythirties; the long playing record mighthave become a commercial successhad further research gone into groovegeometry, and the 45/45 stereo discsould not have waited until the latefifties.

It's conventional wisdom to believethat today's state of the art technologywill filter down to run of the millequipment. Although this has been verymuch the case to date, it has usuallybeen by way of Japan. However, if

Hanoi does not spread its aggression

further, we may reasonably expect tosee a great deal of manufacturingactivity shifttoHong Kong, Taiwan, andpossibly Korea, at the expense ofJapan. Since the motives behind suchmoves will be monetary, the emphasiswill be on low costs, high volume, andnot much innovation. At this point,Japan will be in competition with theU.S. and Europe in the development ofhigh end gear, with its limited market.

Now, even during a depression, therich can always afford adult toys, nomatter how expensive. However, thelarge market among the middle incomepeople will most likely start to dry up,with the demise of many familiar brandnames as a result

I do have great faith in the future ofpower MOSFET technology, largelybecause it can still be utilized within theframework of bi-polar technologywithout requiring complete reorgani-zing of engineering and production. Itcan also offer simpler circuitry, andgreater reliability, important con-siderations in price -conscious market.However, one must be pessimisticabout the immediate future of suchdevelopments as magnetic amplifiers,or the likelihood of completely newtechnologies emerging.

ENERGY EFFICIENCYGreater emphasis will be placed on

making electronics, especially poweramplifiers, more efficient in their use ofsupply power. Not that a great deal willbe gained, since a 100 Watt amplifierreally doesn't use much power ascompared with, say, the incandescentlight bulb, but efficiency will still make agood selling point. More to the point, inthe event of either a real or ficticiousenergy shortage, will be the importanceof power supply regulation. both withinamplifiers, and as regards AC supply.

11

Expect to see more turntables in thelower price class with even greateremphasis on immunity to supplyvoltage fluctuations.

TAPEWith the advent of metal tape, we can

expect to see the demise of theElcassette. Not because it is not a goodsystem, but because it is too late, withtoo little. Manufacturers with vestedinterests in the compact cassettesystem will be unwilling to investdevelopment and promotional funds ina new technology when it can bematched by the old. Open reel tapemachines will still be with us, becausethere will always be a purist market forsuch equipment, and it will be the firstaudiophile application for digitalrecording.

RECORDSRemember, you read it here first:

despite the initial promise, digitized,laser -read discs will not gain a foot -holdin the market. Again, the investment intechnological change -over. Soft -wareis the key here, and I doubt that manypeople will invest in the hardwarebefore the software is available, andthat many people, including producers,will invest in software if the equipmentisn't around to create a market. This willnot be the affluent, adventurous sixties.

Likewise, direct -to -disc recordingswill finally be recognized as thegimmicks that they are. It simply makesno sense to overcome the excesses ofmulti -tracking and multi -stageprocessing by throwing out the wholetape. After all, it was tape which reallymade the long playing record possible.Major labels are not economicallygeared to the kind of limited editionsdemanded by direct -to -disc, and thesmaller labels which are simply cannotattract the class of artist for whoserecordings one would pay hugesumsofmoney. However,digital tape will wipeout any benefits, and, when combined

with half -speed mastering (unuseablewith direct -to -disc methods) will yieldresults far exceeding anythingcurrently produced. If, in addition, the45 rpm speed is adopted for such discswe may indeed get the closestapproach to the real thing. The real pay-off lies in the fact that the tapes wouldstill be useable for the production ofwhat could be called a standard releasefor the mass market, and later perhapseven a budget pressing. Certainlyrecord manufacturers will have to dosomething about the miserablepressings currently being churned outwith high price tags.RADIO

AM stereo will arrive. Largely in anattempt to capture the automotiveaudience by offering them somethingapproaching FM potential in a morereliable mobile reception medium. Thiswill mean a better signal to the home

user, and so better home AM tuners(with stereo, of course).

This will no doubt give a muchdeserved kick in the head to thecharlatans who mangle the audio signalbefore putting it on an FM transmission,and get them to clean up their acts aswell as their audio. There should begreater interest in live (or at least, pre-taped) FM broadcasting, with semi -network affiliations and satellitetransmissions paying the freight.

As for the future of a Canadian audioindustry, well, with Le Grand Rene inQuebec, and sheik Lougheed inAlberta, all presided over by What's hisname in Ottawa, who knows.

Anyway, if the Ayatollah takes overthe world, all music will be banned , soit's game over.

Happy New Year. Hope everybodygot wheelbarrows for Christmas.

Audio Today ProductsAudio developments reviewed by ETI's Contributing Audio Editor Wally Parsons.

TECHNICS MODEL SL -10TURNTABLE

This is the unit unveiled in earlySeptember, which I described as beingthe way it should be done. It is a singleplay, semi -automatic system, housedin an enclosure whose dimensions arethe same as a stack of about a dozenLong Playing records. It featuresTechnics direct drive system with therotor integral with the platter, and astraight line tracking pickup system.

The lower section houses theturntable and drive, nothing else. Theupper section, which is also the lidhouses the linear pickup system, theservo drive mechanism a pressure padwhich fits over the record label when

Jensen Triaxial® 3 -Way SpeakersQuite simply. the most advanced car stereo speaker ever.

For the best sound ever in your car. The first car stereospeaker with a woofer, a tweeter and a midrange.Identical in principle to tote best home stereo speakers.Jensen's midrange picks up a whole range of toneslost to any other car speaker.

Write today for Free catalogues and the name ofyour nearest Jensen Dealer -

len finkler limited111 25 Toro Road, Downsvrew, Ontario M3J 2A6

Telephone 1416) 6309103 Telex 065 24010

the lid is lowered, and all controls, withonly the latter exposed when the unit isclosed. Included is a pickup, a movingcoil unit similar to the 310 MC. Anoptoelectronic sensor controls theservo system, and senses record sizeand speed. Because it is servooperated, the unit may be used in theusual flat position, or on its side. I kidyou not. Some wow is audible whileactually changing orientation, butotherwise there is no audible differ-ence.

Operation is simplicity itself. Openthe "lid", place a record on theturntable, close the "lid", push a button,and enjoy. The pickup is automaticallymoved over the opening grooves,lowered, the turnable rotates at thecorrect speed, and that's it. If you don'tlike who's on the first cut, push anotherbutton and the pickup lifts up andmoves in rapidly, or slowly, yourchoice, until you release it. When therecord is over, or you're tired of it, justlift up the lid, and the pickup is returnedto rest.

The point to a l l this i s that fi nal ly a firstclass performer is useable even by theworst fumble -fingers.

It even includesa built-in pre-preampfor the pickup.

At a price of about $800.00 it shouldbe available sometime in the spring.

Contact Matsushita Electric ofCanada, 5770 Ambler Drive, Missis-sauga Ont, L4W-2T3, or Phone (416)

12 Circle No. 11 on Reader Service Card.ETI CANADA-JANUARY 1980

Audio Today

624-5010. Tell them Wallyfrom ETI sentyou.

Audio Today LettersIf you want to express your views or report on news write to AudioToday, ETI Magazine, Unit Six, 25 Overlea Blvd, Toronto, Ont. M4H 1 B1.

I'll start by saying that I enjoy yourwell thought out and informativecolumn. The letters section is also verygood. Which brings me to my question.

How do I connect a single extensionspeaker to a stereo amp,. I would likethe main speakers to still be in thestereo mode. Would it be easier to justget 2 speakers? Sound quality from theextensions is not of major importance.

Also, what can I do to protect thesmaller extension speaker fromexcessive power (other than putting a

red line on the volume control).Hope you can be of some assistance.

L.C., Port Alberni, B.C.

The secret to a good letter column isin the readers who write. So keep it up,friends.

Several methods are available forproviding a mono feed. The simplest,and, in my opinion, the best, is tocombine the two channels via a mixingpad at the output of the preamp, and

PSB SUMMIT SERIESLoudspeakers.

Paul Barton has a new speaker. And amajordeparturefrom previous designs.No rectangular box. No motionalfeedback. No Philips drivers.

This one is built in the shape of ametronome. Actually, PSB calls it apyramid, but, as the picture shows, itisn't. The purpose is to removeparallelism between the side panels,and the standing waves which result. Inaddition, the tweeter works into a smallpanel area, by mounting it at the apex.This has several advantages which willbe dealt with in a future column.

The bass system isa passive radiatordesign using Bextrene cones whichlook like Audax units. Both models,Summit Nine, and Summit Eleven, useeight inch woofers, the model Nine hasan eight inch passive radiator, whiletheEleven as a 10 inch.

Both use a one inch soft dome Audaxtweeter.

When I heard it, it wasgood enough todisplay the deficiencies of a very goodpickup, even in the clamour of an audioshow, and to reveal the quality of thenew unit which replaced it.

SUMMIT NINE sells for under$900.00, and the SUMMIT ELEVEN forunder $1200.00. Prices are for pairs.

Contact PSB Speakers Inc., P.O. Box144, St Jacobs, Ont, N0B-2N0. They'realso in the phone book.

ETI CANADA-JANUARY 1980 13

Audio Todayfeed the resulting sum to a separateamplifier which feeds the extensionspeaker. Several low power circuitsappear in past issues of ETI, or youmight use one of the many modulesavailable, such as the Sanken, Epitek,ILP, etc. This will also take care of theoverload problem. If your extension isvery efficient and/or you don't wanthigh levels you might use an LM380,LM384, TBA810, etc. Try one of thesumming circuits on page 13 of theApril/'79 issue. Simply connect aresistor of about 27k from each outputto a common point, then a resistor of thesame value from thejunctiontoground.This will not impair stereo separation,but will give about 9dB loss. In the Juneissue I showed an ambience circuitinvolving two speakers in seriesand thepair connected between the left andright speakers, and a resister from thejunction to ground. You could use 8ohm resistors in place of the speakers,and an 8 ohm speaker in place of thesingle speaker. This would provide aload of 12 ohms across each channel,and 6 dB attenuation. If your extensionis efficient enough, you can increasethe resistor values for greaterattenuation, and reduced amplifierloading. This circuit will raise the O ofthe speaker, but if quality is not tooimportant, you might even like the bassrise which results, even though it willnot be too well damped. An L -pad canbe used for level control.

Finally, you can always put twodrivers in one box, but that is a littleextravagant. For your information, I usethe first method in my own system.

If necessary, you can always fuse thespeaker line, but if you use cheap, lowquality speakers, it would probably becheaper to let them blow and replacethem, rather than go into elaborateprotection networks.

Now That's ServiceOrdinarily, in ETI, commentary on

radio broadcasting is limited, totechnical matters, rather than pro-gramming. However, an exceptionmust be made.

As most readers are probably aware,on November 11, 1979, the City ofMississauga, was the scene of thelargest population evacuation in NorthAmerica history, due to the derailmentof a railway train carrying combustiblechemicals, and toxic chlorine.

First on the scene with in-depthcoverage of the disaster was CBC radio,with reporters from many divisionskeeping residents informed with deve-lopments, and aiding civil authorities inevery way imaginable.

CBC Radio normally signs off the airat 1:00 AM and returns at 6:00 AM, butinstead remained on the air, bringing inmorning men Bob Leitch and Joe Cote,who worked the first of many longshifts. Technical staff was on hand allthis time providing appropriate link-

ups with field reporters and others, allon what could only be described as anad-lib basis, meanwhile trying toovercome the interference of anotherradio station.

There is no doubt thattheeffortsofallthese people contributed greatly to thesmoothness and orderliness of theevacuation and re -evacuation of250,000 people, virtually :he entire cityand to the peace of mind of residents ofneighbouring communities, such asHamilton and parts of Toronto.

Since three major road arteriesproviding westerly access to Torontowere closed, it's inconceivable thattraffic could have moved as smoothlyand with sofewtie-ups, without the ablework of CBC's traffic reporter, JirrCurran, probably the best in thecountry.

Compare this performance with thaof the private stations. With these guy.it was business as usual, ersatz musicmixed with commercials, as if the evenhad taken place half way around thrworld. Even in Hamilton, nothing waroffered by any of the stations. And yetlicence to broadcast is supposed tccarry a mandate of service to thecommunity. Some service.

So, the next time some hare -brainedpolitician calls for the dismantling ofthe CBC and its sale to privateenterprise, just mention Mississauga,and November 11, 1979.

Wally Parsons

moti. . . information about the things that interest

you. Use ETI's handy Reader Service Cards. Page58 has all the details. Individual numbers can befound under many of the ads in this issue.

Circle the numbers for those ads that interestyou, mail it to us and more information will be onits way.

'Look, Jasmin, TTL and CMOS ICs, transformers, cabinets andmore! I want to find out more about these guys.'

'Oh Graham. .

14ETI CANADA-JANUARY 1980

ETI Project

Guitar Effects Unit

Our guitar effects unit isn't just a fuzz box. Use it to give you a newsound to play with.

LIKE US, YOU probably thought thatone guitar effects unit was much thesame as any other. After fuzz andWah-Wah, what do you do? Well, wethink we have come up with a newone, which we have christenedstruzz.

With this unit you can select eithera conventional fuzz effect or our newstruzz effect. A depth control allowsyou to alter the sustain rate of theeffect. If the neighbours startbanging the wall, you can instantlycut out the crunchy effects with abypass switch.

SMASHING SOUND

Now you are wondering what struzzsounds like, aren't you. Well, it's adistortion of fuzz. The fundamentalfrequency of the input is full waverectified but the numerous harmonicsare not. The result sounds rather likean antique piano finally succumbingto the ravages of woodworm, andcollapsing. If you play the guitar(we don't) you will, no doubt, findmany more musical uses for thiseffect than we could.

Switching between fuzz and struzzwhile playing produces an interestingsound. You might like to use afootswitch for this purpose.

MAKE-UP

Construction should not pose anyproblems. It's even easier if you useour PCB. Make sure the electrolyticcapacitors are put in the correct wayround. As always, don't plug in theICs until you have checked the circuitthoroughly.Happy fuzzing and struzzing.

FUZZ l* STRUZZ

guitar effects unit

Internal view of the effects unit


Guitar Effects Unit

PARTS LISTRESISTORS (all 5% 1/4W)RI 680kR2R3R4,6,9,10,11R5R14R7R8R12,13

6k8270R10k8k2100k39k820R1k

POTENTIOMETERSRV1 IMO

CAPACITORSC1,3C2

SEMICONDUCTORSQ1ICIIC2D1,2

SWITCHESSW1SW2SW3

MISCELLANEOUS

luO electrolytic560p polystyrene

MPS6515741LF356I N4148

SPDT FootswitchSPOTDPDT

Two 1/41n. mono jack socketsPCB

For pcbs for this project, contact: SpectrumElectronics, P. 0. Box 41660, Hamilton Ont.,L8V 4L5, or B & R Electronics, P. 0. Box6326F, Hamilton Ont. L9C 6L9. NorthernBear Electronics has available a "parts only"kit, see classified ads.

Fig.2. (Below) Circuit diagram

SK1

IN C

R1680k

C1

C2560P

140

SK1BYPASSSW1

RV1

FUZZSW2 RV1 -Ve

Fig.1. (above) PCB component overlay

o GUITAR EFFECTS UNIT o

owl: ama>0 1 If;cel

Complete PCB

R6R2 10k6k8

+'1

01

R3270R

R410k

RV11M0

DEPTH

9V

R14100k

R910k

R1110k

+-r

9V

R121k

ON

SW3a

BYPASS INa

SK2SW1OUT

1771 NOTES01 IS MPS 6515ICl IS 7411C2 IS LF 356ND1-02 ARE IN 4148

V

PIN 4 PIN 4IC1 IC2

4

o OFF

SW3b

ONc.

+ OFF-r¡ 9V


HOW IT WORKS

ETI Project

THE SIGNAL from the guitar pick-up isfed to common -emitter amplifier Q1 viablocking capacitor Cl. Ql has a voltagegain of about twenty-five, and brings theguitar signal up to a reasonable level fordriving the fuzz and struzz circuitry. The

response of Q1 is rest-ricted by C2, in the interest of circuitstability.

Operational amplifiers ICI and IC2 arewired together as a 'precision' full waverectifier, with its true output signalappearing at pin 6 of FET op -amp 1C2. Avery heavily clipped version of the input(Ql collector) signal appears at pin 6 ofICI, and has a peak -to -peak amplitude ofabout 1.2 volts. RVI enables the small -signal voltage gain of ICI to be variedfrom x 10 to about x 110, and controls thedepth and 'sustain' characteristics of thesound effect unit: ICI has a 'large -signal'gain of unity.

The fuzz output of the unit is takenfrom the output of ICI via potential

divider Ra-R9, and is a perfectly conven-tional, heavily -clipped, fuzz signal, withvariable depth and sustain. The struzzoutput, on the other hand, is very unu-sual, and is taken from the output of IC_évia potential divider R13 -R14. In the

mode the original guitar signal isfull -wave rectified, so that its fundamen-tal tone (which passes through zerccross -over points in each cycle) has 't:frequency doubled, but the overtones(which modulate the fundamental and denot pass through zero cross -over poin's)do not have their frequencies altered. Thestruzz output signal also has amplitudedistortion imparted to it, due to the full -wave rectifier action.

Thus, the fuzz output signal has veryheavy amplitude distortion, and tiestruzz output has both amplitude andfrequency distortion. The sound effectsunit can be switched in and out via bypassswitch SW1, and should be interposedbetween the guitar and the ma namplifier.

The PCB and batteries, mountedin the case, showing one ofthe jack sockets on the side ofthe case.

ElectronicMusic andCreative TapeRecording

Electronic Music is the new music ofthe 20th Century. It plays a large part In"Pop" and "Rock" music and, in fact,there Is scarcely a group without somesort of electronic synthesiser or othereffects generator.

It is possible with relatively simpleapparatus to create completecompositions using electronic andsometimes non -electronic musicalsources.

This book sets out to show howElectronic Music can be made at homewith the simplest and most inexpensiveequipment. It describes how the soundsare generated and how these may berecorded to build up the finalcomposition.

With the constructor in mind, severalideas are given to enable a small studioto be built including a mixer and varioussound effect units.

Circuits are included for VCOs, VCAs,Envelope Shapers, VCFs, Active andPassive Mixers, Fuzz, Noise Generators,Metronomes and a 10 -NoteProgrammable Sequencer etc.

All the units shown have beensuccessfully built and used by theauthor and most of the projects can bebuilt by the beginner.

An unusual, fascinating and highlyrewarding application of electronics.

Babani No: BP51Price: $4.50 plus30c postage andhandling. Please usecard in this issueto order.


ETI Project

Series 4000Stereo Amplifier

This month, we present details on how to combine our 60W power amplifier andsingle board preamp into one unit.

The completed stereo amplifier is shown here mounted in a handsome rack -mounting case.

18

WE HAVE ALREADY described theETI 470 60 Watt module (Nov 79) andthe ETI 471 Preamplifier (Dec 79)which have proved very popularas individual designs. This article presentsthe complete Series 4000 amplifier,made from these modules.

We chose to build the amplifier intoa single box, being the most economicalmethod as only one box and powersupply is used for the preamp and bothpower amplifiers. However, this methodhas several drawbacks. Firstly, since thepreamp and power amp share the samepower supply, the regulation for thepreamp must be very good, otherwiselow frequency instability can occur,caused by the drop in supply linevoltage when the outputs draw highcurrent getting back into the preamp-lifier.

Hence we have chosen IC regulatorsfor the preamplifier supply lines.

Secondly, the magnetic field fromthe large transformer and associatedAC wiring required to supply the poweramplifier modules is quite large andalmost impossible to keep out of thesensitive preamp stages. Therefore youwill notice that the specification forhum in the completed amplifier islower than that of the individual units.We took this measurement using astandard El lamination transformerafter rotating it for minimum hum.

The hum induced by the transformercan be further reduced by using a C -core


Everjyjbody's making moneyBelling microcomputers.

SomebodYs doing to make moneyservicing Them.

New NRI Home Study Course Shows You How to Make Money Servicing, Repairing,and Programming Personal and Small Business Computers

Seems like every time you turnaround, somebody comes along with a newcomputer for home or business use. Andthey're being gobbled up to handle thingslike payrolls, billing, inventory, and otherjobs for businesses of every size...to performhousehold functions like budgeting, envi-ronmental systems control, indexingrecipes, even playing games.

Growing Demand for ComputerTechnicians...Learn in Your

Spare TimeEven before the microprocessor burst

upon the scene, the computer industry fore-cast over a 100% increase in job openings forthe decade through 1985. Most of them newjobs created by the expanding world of thecomputer. NRI can train you at home toservice both microcomputers and their bigbrothers. 'IYain you at your convenience,with clearly written "bite -size': lessons thatyou do evenings or weekends without quit-ting your present job.

No Experience NeededYou don't need prior training in elec-

tronics or computers to take this excitingnew course. NRI starts you with the basics,gives you a firm foundation to build on. Andyour personal counselor is always available,ready to help whenever you have questions.

Assemble Your OwnMicrocomputer

NRI training also includes plentyof practical experience. You perform

meaningful experiments building andstudying circuits on the NRI DiscoveryLab Then you build your own test in-struments like a transistorized volt -ohmmeter, CMOS digital frequency counter...equipment you learn on, use later inyour work.

And you build your own microcom-puter, the only one designed for learning. Itlooks and operates like the finest of its kind,actually does more than many commercialunits. But NRI engineers have designedcomponents and planned assembly so it

demonstrates important principles, givesyou working experience in detectingand correcting problems. It's the kind

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Rush Card for Free CatalogSend the postage -paid card today

for our 100 -page, full -color catalog. It de-scribes NRI's new Microcomputer 1chnologyCourse in detail, shows all equipment, kits,and lesson plans. And it also tells aboutother NRI courses...Complete Communica-tions with 2 -meter transceiver...TV/Audio/Video Systems Servicing with training onthe only designed -for -learning 25" diagonalcolor TV with state-of-the-art computerprogramming. With more than a millionstudents since 1914, NRI knows how to giveyou the most in home training for newopportunity. If card has been removed,write to:

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Series 4000 Stereo AmplifierSPECIFICATIONS

Power output 60 watts @ 0.1% THDone channel driven55 watts @ 0.1% THDboth channels driven

Distortion 0.05% THD@ 30 V p -p output across8 ohm load, both channelsdriven.

Hum -70 dB on full outputusing standard transformer

Noise -80 dB on full output

Damping factor 57 (measured at 100 Hz,1 kHz and 10 kHz).

Frequency Response Phono:Within 0.5 dB of RIAAfrom 20 Hz to 20 kHz.(Follows new IEC curve).

Other inputs: 20 Hz to 20 kHz ± 0.5 dBSubsonic rolloff:6 dB/octave below 20 Hz

Tape output 150 mV RMS

Sensitivity For 500 mV RMS outputphono: 3 mV RMSother: 150 mV RMS(Phono overload levelis 400 mV p -p).

Tone controls Bass: ± 13 dB at 50 HzTreble: ± 11 dB at 10 kHz

Filters High: 6 dB/octave,-3 dB at 5 kHz

Low: 6 dB/octave,-3 dB at 100 Hz

Loudness 8 dB boost at 150 Hzand 10 kHz.

Mute switch 20 dB attenuation

type, or better still a toroidal trans-former, which have a contained field,but these are often hard to get andexpensive to the hobbyist.

We feel that the specifications of theamplifier are very good, however thepurist (with plenty of money) may liketo do it this way:

The two power amplifier modules,together with individual power suppliesusing say, 30 000 uF capacitors, couldbe mounted in a separate box to thepreamplifier, which could then bepowered from the ETI 581 regulated supply.

This would no doubt improve thepower output and transient performanceof the amplifier but the cost wouldbe much greater.

CONSTRUCTIONConstruction details for the preamplifierand power amplifiers have beendescribed previously, all that remainsis to house them together, with thepower supply, in a suitable box. Aswe said before, many variations arepossible - here is how we did it.

Assemble the power supply boardfirst, taking care to correctly orientatethe semiconductors, IC regulators andcapacitors. To simplify construction weused pc pins for all terminations to theboards.

The photo of the rear panel showsthe position of the input and outputconnections. Slots are cut in the panelfor the connector blocks and a largecut running across the back panel isused to inset the power amplifiermodules from the rear. Holes then must

be drilled for the ground terminal,external power socket, power cord,mounting screws for the terminalblocks and holding screws for eachpower amplifier - which pass throughthe top of each heatsink fastening it tothe panel.

The case measures approximately 420x135x285mm. and was constructed fromaluminum angle stock with anodized alu-minum sides. This gave us a rigid chassissuitable for rack mounting. If you use anykind of anodized chassis be sure to breakthe finish in order to make good electricalcontact.

One thing to watch though is thatanodised aluminum does not conductelectricity and, after assembling the box,the various metal parts will probablynot be connected to each other, causinga multitude of problems. To overcomethis, strap the rear and side panels tothe common ground point at the head-phone jack on the front panel. (Yes,we found this out the hard way).

After the preamplifier/front panel,power amplifiers and power supplyhave been mounted in the box and theinput/output sockets mounted ontothe rear panel the unit can be wiredas shown in the wiring diagram.

Common to all amplifier designs, theearth wiring is very critical. Mostinstability and hum problems can betraced to ground "loops" or incorrectwiring.

The common lead from each channelspeaker is returned directly to the OVpoint on the power supply. A wire isthen taken from this point and fed toone power module, to the other, andthen to the preamplifier. To avoid an

ground loop the braid of the shieldedcables from the preamplifier to thepower amplifier is not carried throughthe connector block on the rear panel.OV leads for the LEDs and externalpower are also returned to the powersupply common. The common is thengrounded to the chassis at the headphonesocket together with the transformershield and mains ground. This is theONLY ground point onto the chassis.

All the ac and speaker wiring is fedalong the back and down the left sideof the case as shown, well away fromthe sensitive parts of the amplifier.The dc wiring from the power supplyto the preamplifier is carried along thefront.

Lengths of shielded cable with RCAplugs on one end are. used to connectthe input sockets to the preamplifier.These can be made by cutting RCApatch cords to the appropriate length,one cord making two leads. The shieldsof these cables should not be connectedtogether or to the case at the inputsockets.

All that remains is to solder the 330ohm resistors from the speaker switchto the plugs on the headphone socket.

Check that all wiring is correct andthere are no frayed ends. The procedurefor setting the bias current for the out-put transistors is given in the Nov. issue.As soon as this is done insert the 2 Afuses and the amplifier can be switchedon.

If you have the older 50 watt ETI480 modules these could probably beused in place of the ETI 470 module,though we haven't tried it.


electronics ltdAl I ORDERS PROCESSED PROMPTIY. SENDCERTIFIED CHEQUE, MONEY ORDER ORCHARGEX, M/C NUMBER, BANK NAME ORNUMBER, AND EXPIRY DATE.MINIMUM ORDER $5.00. ONT. RES. ADD7%. ALLOW 5% SHIPPING -EXCESS REFUNDED. PRICES SUBJECT TO CHANGE.

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Expandoram Memory Kit 0 K $23916K- $325 48K- $52532K- $425 64K- $599

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Load Imp 4-8 ohms

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1,

.i1 I (1

ETI Project

SW1POWERON/OFF T1

ResistorsR1, R2 2k 1W 5%R3 47k '<W 5%R4 470R 1W 5%

H47011

VOR2 R,

2Y ,IV 2k 1W

CiCq,SOR

<y 0V

PARTS LIST

CapacitorsCl 33n 120VAC metalized

paperC2-05 2500µ 50V electroC6, C7 471 50V electroC8, C9 l0µ 25V tantalum

SemiconductorsD1 -D4 IN5404 or simD5 IN4004, A14A or simQ1 2N3904

2A FUSE

{ 151

LED

O500lCE LEE,

2A FUSE

250I ANT

(:,,1U.. 25V

TTANT

UV TO POWE R AI.,P;O ANO EIN SO(.KE T

0 1 V 10 PRE AMP

COMMON EARTH I' .I'.OOV TO POWER 1.0P', I F 11

SPEAKERS CHASSIS 10,'.',r T

Q ISV TO PRE:!1G

A0010 POWER 051,".Q AND OIN SOCKET

1111,1

Q(lUiL_FISPFAKEu,

Q IN

ot IN

[UGH, SPEAKE RS

IC1 7815, LM340-15, 15Vregulator

IC2 7915, LM320-15, -15Vregulator

MiscellaneousT1 28-0-28 VAC, 2A

transformerFS1, FS2. . 2 amp fuses (if used)RL1 2PST 120 relay

SW1 2 pole 120VAC mini-ature toggle switch.

-40V

I 1

EFS2

AC IN

C4

C5

ID11 D4

IC1

1C2

t I

OV

POWER SUPPLYThe power supply for this amplifieruses a 28V -0-28V transformer rated at2 A to provide +/- 40 Vdc rails for thepower amplifiers. Two regulators, IC1and 1C2, supply very stable +/- 15 Vrails for the preamplifier.

Current limit resistors are mountedon the pc board to power the frontpanel LEDs. This permits some flexi-bility to allow us to think up otherthings to do with the LEDs later.

Fuses are also provided on the boardto protect the power supply from ashort circuit in the do output lines. Ifthe do output facility on the rear panelis not used the fuses can be shortcircuited, as each power module isprotected by its own fuses.

When an amplifier is first switchedon, the two supply lines rarely come upto full voltage simultaneously. Thiscauses a loud `thump' in the speakerswhich may damage them.

PARTS LISTHeadphone socket . . . 6.5 mm jack skt.Speaker switch . two pole, two position,

centre offmin. toggle switch

16 RCA plugs or eight patch leads cut inhalf, two short RCA patch leads, powerlead and clamp.Two, 330R, 1W resistorsTwo, 3 -way plastic terminal stripsTwo, 4 -way speaker terminalsTwo, 6 -way RCA panel socketsOne, 4 -way RCA panel socketOne, 5 -pin DIN socket

C2

C3T

RL1

C6 C7

+40V

1,001.1.111111.

FS1

LED-SOURCE

LEDPOWER


Series 4000 Stereo Amplifier

SPEAKERA/OFF/B

POWERON/OFF

A B C

POWER OUTDIN SOCKET

ACTIVE

RIGHTA SPEAKERS

LEFT

B

SPEAKERS

120V Switched

HEADPHONES

POWERLED

To avoid this an "anti -thump"circuit connects the speakers severalseconds after the amplifier is turned on.

It works this way; as the powerrails come up to voltage a capacitor,

3 CORE CABLE

ETI 471PREAMPLIFIER

RIGHT (OUTPUTS

NOTE SHIELD NOTCONNECTED ONLEFT AND RIGHT 0/P

H F I GPRE -AMP OUTPUTS(MUST BE BRIDGEDH -F 1-G)

OUTPUT

INPUTSRIGHT LEFT

K j\ i PHONO

L

`..,"%";j1 TUNER

N`.,\.1 ` , AUX 1

O`,1...7,11-1 AUX 2

R`TAPE MONITOR

1 TAPE INPUT

1111111.1 }j

ETI 470 MODULE

ETI 472 POWER SUPPLYL

1 1

40V

TAPE INPUTLEFT RIGHT

T W

ALL INPUTS CONNECTED TOPRE.AMPBOARD WITH LENGTHS OF SHIELDEDCABLE WITH RCA PLUG ON PRE AMP END

SHIELDS OF THESE CABLES ARE ONLYCONNECTED TO THEIR RESPECTIVE LUGSON THE INPUT CONNECTOR STRIP ANDNOT TOGETHER

ALL SPEAKER AND AC POWER WIRING ISPLACED ALONG THE BACK OF THE BOXEARTH WIRING AND PRE -AMP POWER ISTOWARDS THE FRONT

J

,

RIGHT LEFTPHONO INPUTS

K

C7, charges via R3. Transistor Qlconducts pulling in the relay, RL1,and connectiong the speakers after thepower rails have had enough time tostabilise.

LEFT (1>:"7. M

AUX 2 PAN L TUNER

Internal wiring and interconnection diagramof the stereo amplifier.


ETI Project Series 4000 Stereo Amplifier

At first we tried mounting thepower supply board in front of thetransformer near the preamplifier, butfound the proximity of the speakerwiring to the tone control stage causedhigh frequency instability if the treblecontrol was advanced. The powersupply board is now mounted at theopposite side of the case to the trans-former and the ac secondary wiringrun across the back.

Two three -terminal connector stripsare mounted on top of the transformer,using the holes in the mounting plates,to take primary and secondary con-nections. The shield (green wire) makesup the third wire on the primary sideand is run to_ gether with the 120Vwiring to the front panel. We usedthree - core line cord for connectionsfrom the transformer to the powerswitch and the power supply pc board.A suppression capacitor (C1)is mountedacross the transformer primary on theconnector block.

Short patch leads will have to bemade up to connect each of the pre-amplifier outputs to their respectivepower amplifier inputs.

This internal view shows the placement of the main modules and the orientation of the powertransformer. The latter will have to be oriented individually to reduce hum levels to the minimumobtainable.


Versatile Logic Probe


If you work or experiment with logic circuitry this project should be invaluablefor debugging circuits. Inexpensive to build, it may be used both with TTL andCMOS circuitry, and indicates HI or LO conditions as well as pulse trains above1 MHz. It will also detect short, isolated pulses having widths down to 500 ns.

INTEREST in digital electronics hasgrown rapidly in the past few years withthe advent of microprocessors and largescalc integration. The most essential testinstrument for experimenting withdigital circuitry is a logic probe.

In its most basic form this shouldprovide an indication of the logic levelat any point in a circuit without over-loading the section being tested. Otherdesirable features are the ability tofollow high frequency pulse trains (pre-ferably over 1 MHz) and to detectisolated, narrow pulses less than 1 µsecin width. Finally, the instrument shouldbe compatible with both TTL andCMOS ICs and be able to operate from awide range of supply voltages (say fiveto 15 volts).

Commercial logic probes that satisfyall these requirements are available, butthey invariably cost over $30. Theprobe design described here offers com-parable performance for less than $10.00combined with an excuse to enjoy agood cigar - a cigar tube is used for thecase!.

Indication is by means of three LEDs.Two red LEDs indicate either a HIGHor a LOW condition on the point undertest, a green LED is used to indicatethat a pulse train is occurring.

The circuit uses a single CMOS ICand a handful of resistors and capa-citors. The components are mounted ona small pc board and housed in a tubularcase such as an aluminum cigar tube ora length of plastic conduit. The power issupplied from the actual circuit undertest and the performance characteristicsof the prototype are described in thespecification listed here.

rrF»rr

®® =£ illA logic probe is an invaluable aid for debugging or servicing digital circuitry. This project isinexpensive and easy to build.


ETI Project

The circuit is simple, involves a single CMOSIC, three LEDs and a handful of othercomponents.

-- SPECIFICATIONS-

TTL or CMOS compatible Supply voltage: 5 to 15 volts Input impedance: over 400k Indicates HIGH (1), LOW (0) orfloating states

Follows high frequency pulsetrains - over 1.5 MHz

Detects single pulses down to 500nsec in width, and stretches theseto 15 msec.

Relative brightness of HIGH/LOWLEDs indicates duty cycle of pulsetrains.

CONSTRUCTIONA printed circuit board is recommendedfor this project to provide consistentperformance characteristics.

Before attempting to mount thecomponents on the printed circuitboard check to see that it fits easily intothe case. The board must be a looseenough fit to allow it to be moved upand down within the case over a rangeof at least 5 mm. (Refer to the diagram).

If this is not possible, the width ofthe board can be reduced slightly with afile or coarse sandpaper, taking care notto remove too much or to damage thecopper portions of the board.

The other alternative is to use alarger case - buy a bigger cigar! Thismovement within the case is necessaryso that the LEDs can be juggled intoposition in the holes in the casing (seelater).

Mount the wire links, the resistorsand the capacitors on the pc board,keeping all components as close to theboard as possible. Note that C3 ismounted on the underside of the board.Next, install the three LEDs. The heightof the LEDs above the pc board must besuch that the assembly will slide intothe case with the board pushed downagainst the bottom of the case (seediagram). For a 20 mm diameter casethis height should be about 12 mm. Ifthe LEDs are not high enough, then itwill not be possible to push the assem-bled board up into a position wherethe LEDs project through the holes inthe case.

Next, add the power leads (withoutclips or E -Z hooks at this stage) and the10 cm wire to the probe tip. Last of all

R2680k

R91k

INPUT FROMPROBE TIP

'SEE TEXT FOR DETAILS

R3560k

C2... 100p

IC1 IS 4049APIN 1 IS +VePIN 8 IS OV

CONNECT PIN 9 TOVDD OR PIN 11

C3100n

R8220k

C4ton

o+5V -+15V

+ICs1N

TOPTIONAU

HOW IT WORKS

Three of the six inverter/buffers in IC1 areused in the high/tow detection circuit.IC1c is connected to the probe tip via R9.When the input goes HIGH (logic 1),IC1c output goes low and illuminatesLED 2 through R5. Similarly when theinput goes LOW (logic 0), the series pairIC1e and f illuminate LED 1 through R4.The resistor network R1, R2 and R3ensure that the outputs of both IC1cand IC1f remain high when the input is'floating'. Cl is connected across R2 as a'speed-up capacitor' to maintain a sharppulse shape into IC1e and so improve theability to follow high frequency pulsetrains (over 1MHz)

The two inverters IC1a and b form amonostable circuit that stretches shortpulses (less than 500 nsec) out to 15msec (0.7RC) using C3 and RS. The input

OVO

of the monostable comes from the outputof IC1c and is isolated from the DC levelof this output by C2. The combination ofR7 and D1 normally holds IC1b inputhigh. When a negative going pulse is fedinto IC1b through C2, the output goeshigh, forcing IC1a to go low and illuminateLED 3. Diode D1 ensures that the inputto IC1b is kept low (0.7V above zero) solong as the output of IC1a remains low.This prevents subsequent pulses from re -triggering IC1b until the monostableitself retriggers via discharge of C3 to earththrough RS, and allows IC1a output to gohigh, switching off LED3.

Capacitors C4 and C5 (optional) conferimmunity to spikes or pulses in the supplylines, which are taken from the circuitbeing tested.

solder IC1 into position, observing allthe usual precautions - shorted pins,heat sink, earthed soldering iron, pins 8and 16 soldered first.

The probe tip housing on my proto-type was turned from perspex and a2 mm hole drilled through the centre.The probe tip wire is soldered to theend of a darning needle which iscemented into the housing with epoxy,allowing the needle to project about15 mm beyond the end of the housing.It is not necessary to use a perspex cone,turned up as I have it. A flat -faced plugof a suitable material will suffice equallywell.

Drill the 3mm holes for the LEDs at10 mm intervals, starting 75 mm fromthe front of the case. The hole for thesupply leads is drilled in the back of the

case and fitted with a small rubbergrommet (or plastic LED housing) toprevent the case rubbing through theinsulation on the leads.

Before mounting the assembledpc board in the case check the circuitfor dry joints, solder bridges, incorrectlymounted components, etc. Then testthe device as follows. Connect to a fivevolt supply and observe the three LEDs.None should light with the probe tipisolated. If the LOW LED (LED 2)comes on or flashes, then R2 is toosmall and must be replaced by a slightlylarger resistor (say 820 k). Touching theprobe tip with the fingers may causeLED 2 to light, but this should go offwhen the tip is isolated. Touching theprobe tip to either supply rail shouldlight the appropriate LED, with the



TO PROBETIP

DARNINGNEEDLE(EPDXY IN POSITIONI

A

131111

...r R9-,_1. R2-1,-r

NOS LEAD SOME TOPESNOMA ORLONGER

*

LED2

1)

NOTEC5 IF USED IS MOUNTEDACROSS C4 (OBSERVEPOLARITY)

CONNECT RESPECTIVELETTERS TOGETHERATO A B TO B etc.

+Ve

Ú SUPPLY1 LEADS

Component overlay for the pc board. Refer to theconstruction diagrams below for correct assemblingof the LEDs.

or° ° óETI 148

1141op-O

PROBE TIP HOUSING

r

ASOFT WOOD ORPLASTIC WEDGE

10m . lo._7SR.m - - -

1

CIGAR TUBE CASE120m1n 1.01

2

ROLE FORLED

RANGE OFPOSSIBLEMOVEMENTIAT LEAST Smml

DGE

POWER SUPPLYLEADS

RUBBERGROMMET

OF WOODOR PI ASTIf

For pcbs for this project, contact: SpectrumElectronics, P. O. Box 41660, Hamilton Ont.,L8V 4L5, or B & R Electronics, P. 0. Box6326F, Hamilton Ont L9C 6L9. Spectrumalso has available a kit of parts.

PARTS LIST

Resistors all '4W, 5%R1,7 ... 2M2R2 .... 680kR3 .... 560kR4,5,6 820RR8 .... 220kR9 .... 1k

CapacitorsC1,2 ... 100p CeramicC3 100n GreencapC4 10n GreencapC5 1p Tantalum (Optional)

SemiconductorsICI . 4049LED 1,2 . 3mm redLED 3 . . 3mm greenD1 .. . . 1N4148 (or equivalent)

Miscellaneouspcb; red and black leads with alligatorclips or E -Z hooks;cigar case (or equivalent) - minimumdimensions 20mm ID, 140mm long;perspex rod for probe tip housing;darning needle.

" Resistors R2 and R3 may have tobe altered slightly (in the range470k to 820k) to suit the transfercharacteristics of IC1 - see text.

These diagrams above, and the picture leftshow the general construction of the probeand the drilling of the cigar tube or whatevercase is used.


StLYP 6841.4001V.:

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Eamon Canada Am WOuthaSSOOMIS ao, Coe yr.

Se texeni Deter n. re'Mahone 51.1 p GA I

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MORECIRCUITS

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IOSLISHI II

CANADA'S' OWN ELECTRONICS MAGAZINE

FEATURES & INFOCIRCUIT CONSTRUCTIONTHE IMPORTANCE OF INSTRUMENTS 12EASY DIGITAL PANEL METER 16E TI PUBLICATIONS AND T SHIRTS CENTREETI SUBSCRIPTIONS CENTRE, 93ETI CIR 1 CENTRE, 105CRYSTALL OSCILLATORSATORS 99SPEAKER CROSSOEN RES

NOTES ON COMPONENTS 100CMOS FUNCTIONS 102TTL FUNCTIONS 102TRUTH TABLES 103TTL PINOUTS 10.

P1NOUTS 105ADVERTISERS DE% RIG

CIRCUITSAl AR MS

Burglar AlarmSCR AlarmsCr FM. ProtectorFoe Alarm

R SPREAMPLIFIERSNominee.,C Ampl Iw Simiiopi.s

Voltage FollowerFlom.

2. Ri GenResponse

Volta. Controlled Ampd.rRecordIA* Imwe.n. 5,0.Doect Coupled PowerCMOS Power Booster

20

21

anpd.m12 Volt PA System

Op Amp Locum., StandardSIGNAL PROCESSORS

Hoed CS,Tree. end Hoid. s milpleADSR Envelop ShaperFrequency Doubler

Vol Convertero,p oHouma nta.

alog:e ConvertorSpbmin TOMM...out Hvdm.ie

IM Lengthener, OpmuSIGNAL GENERATORS

Square Were Low frg.n.ySum Wm Generate

Tom. lei waveform GeGeneratorMarker GeneratorVoltage Controlled OecdlaorVdte. rd Frequency CabbalaVCO SoilTore Burst GeneratorSur Wave 0r10/Examen., Waveform GenernwTlwrrnator O.cdIrtw

22 FILTERS22 Voltage Controls. F Me,22 CMOS Fns.24 Lwdnw. Control26 Rumble Filter, Swbtguble26 Tone Contra, Acne26 Tai. Contra Grun26 SPECIAL EFFECTS29 Wu1tar

26 .Ming Alarm

303032323A

353536

373736

36

39

4242.43

45

b

Gw;Mueller Transmomsl

MIXERS

DETECTORS 6 COMPARAT(7xStow Battery Warn,

MauComparator VoltmeterVoltage ComparatorTrue RMS DleotorBattery Voltage

re Sensor D rte« belTrue RMS Convertor

So 555Poem.

mtPm Detector

INDICATORS

Warmth eSensor. Remote

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Obtain your copy of this new publication directly from us by using the order card in this issue. Or send a cheque,money order, or Visa/Mastercharge information for $4.50 plus 45c postage and handling to: MORE CIRCUITS,Electronics Today Magazine, Unit 6, 25 Overlea Blvd., Toronto Ontario, M4H 1131.

PS. The real book Is orange.

Versatile Logic ProbePULSE LED flashing when the tip firsttouches the positive rail. If the LOWLED does not light when the probe isconnected to 0 V, then R2 is too large.Change R2 to 560 k and repeat thesequence above.

Now try a 15 volt supply. Again, allLEDs should be extinguished when theprobe tip is isolated. The HIGH LED(LED 1) may glow very faintly. If thisglow is too strong, reduce the value ofR3 to say 470 k. However, if R3 has tobe altered it will be necessary to recheckthe circuit at 5 V to see that the lowvoltage performance is still satisfactory.At 15 volts repeat the process of touch-ing the probe tip to the two supplyrails. The results should be the same asin the case of the 5 volt supply, but theLEDs will be considerably brighter.

When satisfied that the circuit workscorrectly mount it in the case. First,cover the edges of the pc board withstrips of tape to insulate it from the caseand apply a thin smear of epoxy cementaround the base of each LED. Feed thepower supply leads through the back ofthe case, followed by the assembledboard. Jockey the board into a positionwhere the LEDs are directly under the

The completed logic probe.

holes in the case and then push theassembly up into a position so that theLEDs protrude through the holes in thecase. The epoxy around the base of theLEDs will anchor them in position. Inaddition to this means of holding theboard in place, a small wedge of softwood, plastic or similar insulatingmaterial can be inserted into the spacebetween the bottom of the board and

the case. The probe tip and its plastichousing is then inserted in the front ofthe case and epoxied in position.

When the epoxy has set, fit theclips or E -Z hooks to the ends of thesupply leads, label the three LEDs andgive the whole instrument a coat ofprotective lacquer. The completed logicprobe is now ready for use - butdon't forget to smoke the cigar!

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ETI CANADA-JANUARY 1980Circle No. 13 on Reader Service Card. 29

The LM10-Applications

Following on from last month's introduction, Ray Marston takes a closer look at the revolutionaryLM10 amplifier, and comes up with a whole stack of practical applications.

THE LM10 IS A REVOLUTIONARY new type of operatio-nal amplifier device that is capable of operating fromsingle ended supplies with voltages as low as 1 V1 to ashigh as 40V. As can be seen from Figure 1, the devicecontains an op -amp, a precision 200 mV band -gapvoltage reference, and a reference amplifier, all housed inan 8 -pin package. We introduced basic details of theLM1 0 in the last edition of ETI.

BALANCE OUTPUT

2

INPUTS

Fig. 1. connections.

REFERENCEOUTPUT

8

200RI VREFERENCE

REFERENCEOUTPUT

In this month's article we take a look at a whole stack ofpractical application circuits of the LM 10

VOLTAGE REGULATOR CIRCUITSThe LM 10 is, because of it's built-in precision voltagereference and op -amp, ideally suited to use in voltageregulator applications. Figures 2 to 9 show a few practicalcircuits of this type.

Fig. 2. The built-in reference andamplifier are used to generate a200 mV to 20 volt potential that isfed to the input of the op -amp,which is configured as a voltagefollower and boosts the availableoutput current to about 20 mA.

RV1

AITs vrawmlRv To 70v9-aE,RA

R11E0

V.I 22V1

Fig 3: the reference and amplifier produce a fixed 20 volts, whichis fed to pot RV1 . The op -amp and Q1 are configured as a voltagefollower, which boost the 0-20 volts output to current levels upto several hundred milliamps.

Cl .V.I5)/21

Void5V, 020mÁ,

Fig 4: the op -amp input is derived directly from the 200 mVreference, to give a 5 volt output. Fig 5: the op -amp input isderived from a 0-200 mV reference, to give a 0-5 volt output.

R23k9

.I TV)


The LM1O-Applications

R3Sk

Vwt - 200mV (RI . RO)RI

.V.I.- 53V1

Q22030154

R63305

NOTES01-02 ARE 2N3064

Q3 IS 203056

0V/7177

Figures 8 and 7 show how the LM 10 can be used in the 'floating'mode, to generate high output voltages. Note in both of thesecircuits that the IC is used in the 'shunt' mode, with loadresistor R3, and that only a few volts are developed across theLM 10 itself.

.v. 1 2110V I

Vout 200mV IR1 . R21

NOTE.01434 ARE 1N467

The LM10 can be used in a wide variety of voltage,current, and resistance -sensitive fault -indicator circuitswith audible or visual outputs. Figures 10 to 23 showexamples of circuits of this type.

In Figures 10 to 1 7 circuits, the op -amp is used as asimple voltage comparator, with its output feeding toeither a LED indicator or an audible warning device via asuitable current -limiting resistor.

'V. (5V5 TO 1'V51

Figure 8: a simple example of the use of the LM 10 as a 5 voltshunt regulator. Fig 9: how the IC can be made to act as anegative voltage regulator.

01

2N3904

V. 1 > Vtny1

VtrE 20(knV IA" _R2)RO

R320 ,A CURRENT

LIMIT

V1200mV TO 400I

Fig 10: over -voltage indicator circuit, the test voltage is fed tothe non -inverting terminal of the op -amp, and the triggerreference voltage is produced by the LM 10's voltage referenceand reference amplifier and is fed to the non -inverting terminalof the op -amp.


Vin(200,,,V TO 40V)

VE 1 > Vtnpl

Vhip- 200mV IRl R21R1

R32OmA CURRENT

LIMIT

AUDIBLEWARNING

OF ICE

rig 11: An alternative approach is used in the over -voltage circuithers. A 200 mV reference is fed to one input terminal of the~imp and a potential -divided version of the test voltage is fedto the other.

Vb. 1200mV TO ~I

Vp (2.6V TO 40V1

V Vip - 20OnV (RI R21

OV

R32OnA CURRENT

LIMIT

----1AUDIBLEWARNING

DEVICE

J

Fig. 12: under -voltage circuit it similar, except that the op -ampinput connections ere transposed. A feature of both of thesecircuits is that the IM 10 supply voltage must be greater than therequired trigger voltage.

Vi, (200,4V TO -I

4.v. (2_6V TO 40V)

V

Vtr,p-200,,,V IR1. 02)A1

R32O.,A CURRENT

LIMIT

--AUDIBLEWARNING

DEVICE

_J

Fig 13 (above): precision under voltage indicator with LED oraudible warning. Input sensitivity 50k /v.Fig 14 (below): precision over voltage indicator with LED oraudible warning.

.Vp 12.5V TO 40VI

R320mA CURRENT

LIMIT

A11OIBLEWDEARVICNING

E

.Vp 12.6V TO 40V)

01140 Itrlp-20AnV

R31OnA CURRENT

LIMIT

Fig 15 (above): precision under current indicator with LED oraudible warning device output.

.V, 12.5V TO 40VI

NOTER1- CADMIUM -SULPHIDE PHOTOCELL

ORnK THERMISTOR, WITH BOOR TOONO IMPEDANCE AT TRIGGERLEVEL

RB2OnA CURRENT

LIMIT

RV10,SETLEVEL

Figures 16 and 17 show precision circuits that can be triggered byany paramters, such as light or temperature levels, that can besensed by a resistive element. In these circuits, the resistiveelement forms part of a Wheatstone bridge that is powered fromthe LM10's voltage reference amplifier, and the output of thebridge is used to activate the comparator -connected op -amp. Inthe examples shown, the bridge is powered from a 2V2 source.

R1

RV110kSETLEVEL

.Vp12.5VTO40V1

R210k

R310k

oNOTERI - CADMIUM -SULPHIDE PHOTOCELL

ORd THERMISTOR WITH BOOR TO

OW IMPEDANCE AT TRIGGERLEVEL

LED 1

R610mA CURRENT

LIMIT


The LM1O-ApplicationsREMOTE AMPLIFIER AND 2 WIRETRANSMITTERS.One of the most interesting aspects of the LM 10 is itssuitability for use in remote -amplifier and 2 -wire trans-mitter applications. The device has an output currentdrive capacity that is a couple of orders of magnitudegreater than the devices quiescent current value, and hasexcellent supply -rejection characteristics. Consequently,the device can operate quite happily with its outputterminal shorted to one or other of it's supply terminals, inwhich case the supply leads can be used to carry bothsupply and output signal currents.

RI

MIC300 TO 125

tSV

,k2

OUT(OF SET)

- 2V2

Rt100

R2155

0V

R4152

Vout1V5 WHEN R 0 3V0 WHEN R. -R3

Fig 21 (above): a two -wire transmitter for use with a variableresistance sensor.

Figures 22 to 26 show the circuits of 2 -level 2 -wirefault -indicator' transmitters with either resistor, LED, ortransistor outputs at their 'receiver' ends. Figures 25to 30 show 2 -wire 'fault indicator' transmitters with eitherflashing LED or monotone audio outputs.

Vtnp- 200 .V (R1 112)

Fig 18 (above): remote 20dB voltage amplifier for use with R2

inductive or magnetic input devices.

Cl10u

MIC300 TO 12k

OV

.5V

OUT(OF SET)

- 2V2)

Fig 19(above): remote 40dB voltage amplifier.

Figures 18 to 21 show examples of remote linearamplifiers or 2 -wire analogue transmitters. The Fig 18and 19 circuits are suitable for use with low- to mediumimpedance input devices, such as moving coil or mag-netic microphones, etc., and the Fig 20 circuit is suitablefor use with high impedance devices such as crystalmicrophones or vibration sensors, etc. The Fig 21 circuitis suitable for use with resistive sensors.

XTALINPUTDEVICE

V

.5V

152

OUT(OF SET/

2V2)

Fig 20 (above): 20dB voltage amp for use with high impedanceinput device.

Vin )200,,V TO >I R210k

LED 1

LM10C

p

4

R3MDR

/100R',FORLED

IOUTFU

VoutOFF 4V8ON IV8

R4152

0,

.5V

iRS Vold155 OFF 0V

ON4Vt

OV

Fig 22 (above): two wire precision over -voltage transmitter withLED or resistor/transistor output.

LED 1

Vtrip- 200mV (RI 02)R2

VousOFF - OV

N - 4VE

Fig 23 (above): under voltage version of Figure 22 circuit.Fig 24 (below): over current version of basic circuit.

LED 1

N

Htip 2_0_OmV

R1

02150

R1

3

-SS7

LMIOC

R35400

100R FORLED OUTDO

VoutOFF 4VE

ON 1V5

5V

04152

RS Vout155 OFF OV

ON 4VS

OV


The LMIO-Applications

I nip - 200,nVR7

7

VatOFF 4V11

ON 1V5

R36400

0011 FORLED

OUTPUT

V

LED 1

.5

RN Vout104 OFF 0V

ON 4V8

Fig 25 (above): two wire under current transmitter with LED,resistor or transistor output.

NOTE:RI - CADMIUM -SULPHIDE PHOTOCELL OR

C ANCETHERMISTOR WITH 500E TO 940IMPEDANCE AT T RITO R 5009LEVEL

4

7

LM OC

4-AvA/^44.~-RI R510k 106

RV1104SETLEVEL

111

112

10k

R310k

RS6808

100R FOR

OUTPUT

LED I

.5V

A 67162

VoulOFF 4V8ON 1V6

t ( 1 01

Ra166

VwtOFF OV

ON 45,8

V

Fig 26 (above) two wire precision 'dark' or 'under -temp'transmitter with same basic outputs as previously. TransposingR1 and RV1 makes the circuit act as a 'light' or 'over -temp' alarm.

7

RI100k

0V/7177

SS

R8100R

R9

AA AA162vvV-

3110 TO 256

.5V0

NOTES'FOR LED OUTPUT, Cl- 220n, R7. 1M0

FOR SPEAKER OUTPUT, Cl 10n, R7 Bak

VtnF 200t4V 1145 RslRs

R91k2

1 ( LEO 1I ¡ 1

SPKR

100 TO 25R

5Vo

FOR LED OUTPUT, CI . 220n, 67. 1M0FOR SPEAKER OUTPUT, Cl 10n, 07 - 684

VIn9 200mV I65 R51

116

100R

0V

R6

Fig 28 (above): over -voltage transmitter -- output options on Fig27.

R210k

081009

R9162

14 X4 LED 1

1 i

3140 TO 25R

.5V

NOTES:FOR LED OUTPUT, CI 220n, R7 IMO

FOR SPEAKER OUTPUT, Cl 10n, R7 - 68k

It,l9 200mVR6

Fig 29 (above): under -current transmitter - output options as Fig27.

Fig 30 (below): over -current transmitter - output options as Fig27.

RI101

R20 101

Fig 27 (above): two wire precision under -voltage transmitter withflashing LED or monotone audio output (400 HZ).

R91k2

LED 1 1

1

»k SPKR360 TO 25R

NOTES:FOR LED OUTPUT, Cl 220n, 97 - 1M0

FOR SPEAKER OUTPUT, Cl . 10n, R7 686

Itrio 2001nV

R81000

V

RS


-: . ... .. x:{nk .} A};±\i:: ^4Y+.. <- 4.. n.. ' N }y: .'? v. Y 4A+y':.: i:J^ J 4 4'. :'.}t 3ri:'F.ttP,9.ºh,^t^..tK::F.:::::<:^2.!:::.:'..}'::::C:;::: :.:...tC.i" Y,ky:..... ofi::.:.`1C x0i.:mff8+.ó4R fs.h:,,x}}?F...w^...atfXic3.9::tNAwSi..;4??ri%1%bf,?2'f}33K::Ti:4,:Y..xa/a'.2:!:;¿'......Y.....; 1QR -::::::: 'í:::93R..:... A.L,`Gs3.

TOWER'S INTERNATIONAL TRANSISTORGUIDE is now available from ETI. We are proud tobe able to bring you this "bible" of transistor data.It contains data on over 13000 transistor types, 2Ns,2SCs, European and "replacement" types. Informa-tion includes polarity, material, package and leadinfo, maximum ratings for VCB, VCE, VEB, IC, TJ,P, minimum FT, HFE, typical use, manufacturer .and suggested equivalents.

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The LM1O-ApplicationsMETER AMPLIFIER CIRCUITSTo conclude" this look at applications of the LM 10, Figures31 to 33 show a variety of ways of using the device as amoving -coil meter amplifier.

R3100k

T1VS

RV15009 _ySET 10pmVNd

100mV R2 9410uA 10k 13110R

1MA

Fig 31: the op -amp is used as a simple non -inverting amplifier,and increases the meter sensitivity by a factor of about 100. Thiscircuit has no 'set null' facility, and can give no indication ofreverse -connected signals. The modified circuit of Fig 32(below) does not suffer from this defect.

100nm V/uA

R3100k

©LM10CRVI T

irniliewe

GV11k0SET +NULL

0

Fig 33 (below) how the basic Fig 32 circuit can be adapted for useas a four -range DC millivoltmeter. Note that these meter circuitsare powered from a 1V5 cell! Not bad for an op -amp.

SW1

INPUT

ó

TVo

100mV

1mV

Ni900k

R290k

R39k0

R41k0 R5

1k0

iRV11k0

SET NULL

Re1M0

+RV25k0 1V5SET fid

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Practical Guide

To Triacs Part IIPart 2 -Phase control

i//

//

rTriac is triggered at this point.

Fig. 16Drawing shows Triac triggeredat half -way point.

TRIACS not only switch poweron and off and thus replacemechanical contactors - they

can also control the amount of powerapplied to a load.

There are two quite different ways ofusing Triacs for this purpose - 'phasecontrol' and 'zero voltage switching'.

Phase control is the method used tocontrol light dimmers, electric motors,and for voltage and current regulators.

Heating loads can also be controlledin this way - but, for reasons outlinedlater in this article, zero voltageswitching is a better technique.

HOW PHASE CONTROLWORKSA Triac can be triggered into

conduction during any part of ahalf -cycle of applied voltage, and willremain conducting until the end ofthat half -cycle.Thus, if a triggering signal is applied

at the beginning of each half -cycle, theTriac will in effect conduct as if itwere a switch that had been turned on.But if the triggering signal is appliedhalfway along the waveform, the Triacwill conduct only for the remainingperiod of that half -cycle; and as theTriac conducts for only half the time,it reduces the power applied to theload by roughly the same amount (Fig.16).Thus the power input to the load can

be set at any level simply by

Fig. 17

Actual waveforms of a domestic light dimmer showing triggering at %, % & % points. Note corresponding changes in lamp brightness.

0MODE,

555; OSCILLOSCOPE

OLTS/CM TRIGGERING

swear

TIME/CM

MODE L

555OSCILLOSCOPE

VOLTS/CM TRIGGERING

s,..,,Irt

CTIME /C


Practical Guide To Triacs Part II

Fig. 18Basic phase control circuit.

controlling the point at which thetriggering signal is applied.Oscilloscope pictures (Figs. 17a, b, c)show the 60Hz waveform triggered atthree different points. Notice thecorresponding change in brilliance ofthe lamp used as a load.

LIGHT DIMMERThe circuit of a commercially

produced light dimmer is shown inFig. 18.

During each half -cycle the 0.1 pfcapacitor charges up (via the controlpotentiometer) until it reaches 30-32volts. At thisvoltage the trigger diodeconducts and the voltage across thecapacitor 'gates' the Triac intoconduction. (A neon lamp is

"-1 Loarli

= 0 1 µfAC

0Fig. 19Simple versatile phase control circuit is suitablefor domestic light dimming and other resistive loads.

sometimes used instead of a triggerdiode).

The time required for the 0.1µfcapacitor to charge to the diodetriggering voltage is determined by theresistance of the controlpotentiometer. When this is reduced tozero, the capacitor will charge to thetrigger voltage instantaneously and the'Triac will be gated into conduction forpractically the complete half -cycle. Atmaximum potentiometer resistancethe capacitor may not reach the diodetriggering voltage until the end of thehalf -cycle, and the will conductfor only a very short time.

The circuit shown in Fig. 18 is verysimple and cheap'to make but has onemajor limitation - namely, that powercannot be controlled smoothly from

Trigger diode

0.1µf

zero to maximum. As thepotentiometer control is advanced, theload current will jump quite suddenlyfrom zero to some intermediate valuefrom which it can only then becontrolled smoothly in eitherdirection.

If the power supply is momentarilyinterrupted while the lights aredimmed below this 'jump' (hysteresis)level, the lights will remain off whenpower is subsequently restored.

REDUCING HYSTERESISThe hysteresis effect is considerably

reduced in the circuit shown in Fig.19. This circuit is ideal for use as adomestic light dimmer. Allcomponents can be mounted behind awall switch plate - and if the load


does not exceed 200 watts, the Triacwill not require a heat sink.Almost total freedom from hysteresis

o

is required for theatrical light WHAT SIZE TRIAC?dimmers. This can be achieved byusing the circuit shown in Fig. 20.

Fig. 20

Suitable for theatrical light dimming, this circuit has very low hysteresis.

o

ArC

IFig. 21Zener stabilised circuit maintains constant pre-set output despite changes in line voltage.

0---1 Load

15k

20v ttruri

Lu,tcl

901PfII

11IllrIII 1

A/C

Í

150k

4 / F.

1pt 0 1pt

Fig. 22Photo -cell switches Triac on at night, off during day.


500k

I.5k

Incandescent lamps draw a veryheavy current during the time takenfor the filament to reach operatingtemperatures. This on -rush currentmay exceed the working current by 10to 12 times. Fortunately domesticlight bulbs reach working temperaturewithin a cycle or two, and theshort-term overload is absorbed by theTriac.This does not apply to theatrical

lighting equipment, where the largerwattage bulbs take longer to reachworking temperature. For this type ofuse the Triac must be rated to carry atleast five times the normal maximumload.

VOLTAGE FLUCTUATIONSAll the control circuits shown so far

are voltage dependent - that is, theoutput voltage changes if the inputvoltage changes. This voltagedependence can be overcome by usinga circuit in which a zener diodestabilizes the voltage across the timingcapacitor (Fig. 21).

This arrangement will maintainpractically constant output despitesubstantial changes in line voltage. It isfrequently used in photographic andother applications where a constantlight level is required.

FLUORESCENT LAMPSWith all the phase control circuits

shown so far, incandescent filamentlamps can be controlled with nofurther modifications to the houselighting system. Fluorescent lamps canalso be dimmed by this type of controlunit

Quartz iodine and similar lamps usinga regenerative halogen cycle shouldnot be dimmed for any length of time.If the envelope temperature of thelamp drops below 2500C, theregenerating halogen cycle ceases.Tungsten from the filament will bedeposited on the wall .of the lamp,reducing filament life and decreasingthe light transmission of the glass.

A modification which can be usedwith any of the circuits discussed sofar is shown in Fig. 22. Thisarrangement turns lights on asdarkness falls and turns them off againat daybreak. The photo cell must seeambient light and be shielded from thecontrolled light.

0129-------L1

100µH

MOTOR SPEED CONTROLTriac phase -control can be used to

vary the speed of electric motors.The universal type of series-wound

motor may be controlled by circuits

Practical Guide To Triacs Part II

similar to those used for light dimming- except that, to ensure reliablecommutation, a capacitor and seriesresistance must be connected inparallel across the Triac (Fig. 23). Withthis arrangement the speed of themotor will vary with changes in loadand supply voltage, but for non -criticalapplications (such as fan speedcontrol), where the load is constant atany given speed, the circuit may wellbe adequate.

Motor speed which, once pre-set, is

maintained despite load changes is auseful characteristic for power tools,laboratory stirrers, watchmakers'lathes potters' wheels, etc. To obtainthis 'load sensing' characteristic, anSCR is commonly used in a half -waveconfiguration (Fig. 24). The circuitworks quite well over a limited rangeof speed but is prone to low -speed'cogging' and the half -wave operatingprinciple precludes controlledoperation much beyond half speed.

A load sensing phase -control circuitin which a Triac provides full zero tomaximum control is shown in Fig.25. This circuit is described in detailon page 33 of this issue.

INDUCTION MOTORSInduction motors can also be Triac

controlled - but some problems maybe encountered, especially withsplit -phase or capacitor start motors.

In general, induction motors can becontrolled between full and half speed,providing they are not run at fill load.A reasonably reliable guide is motoroperating temperature. This must notexceed the manufacturer's rating atany speed.

Once again, the modified lightdimmer circuit shown in Fig. 23 canbe used, but the load should beconnected in the alternative positionshown in dotted lines.

VARYING TRANSFORMERVOLTAGEThe circuit arrangement described

above can also be used to vary thevoltage in the primary winding of atransformer and thus obtain anadjustable secondary output.

This arrangement was used in a rangeof microscope lamp controllersdesigned by the writer some years ago.An adjustable zero -set was obtained byreplacing the 47K resistor by a 100kpotentiometer.

HEATING LOADSAny of the Triac phase -control

circuits shown so far can be used tocontrol heating loads, although theETI CANADA-JANUARY 1980

/1f

_ _J

4/k

H1

Alternative load position

500k

U6

0---1 Load

A

O a

150k

I

IFig. 23Phase -control circuit forinductive loads, it may benecessary to connect the loadin alternative position shownto obtain adequate control.

Fig. 24.Half -wave SCR circuit providesfeedback speed control.

Fig. 25

This full -wave load sensingcircuit will control ac/dcmotors over wide speed range.

0 1µf =

SCR

41

Practical GuideTo Triacs Part IItemperature of the controlled load willvary with changes in line voltage andambient temperature.A circuit which compensates for

these changes is shown in Fig. 26.Theoretically this circuit can maintaintemperature to within 1% of the setpoint despite line voltage changes of}10%. Actual performance dependsupon the design and constructionof the system in which the controlleris used.This circuit provides proportionalcontrol -that is, full power is appliedto the heating elements while the loadis warming up, until, at someintermediate state, the power is

reduced by an amount proportional tothe difference between the actual loadtemperature and the required loadtemperature. The proportional band isadjustable by a 'gain' control.

The circuit is simple yet effective,but it has one major failing whichrestricts its use to all but light loads.This is radio interference.

RADIO INTERFERENCEAll phase control systems generate

large amounts of radio interference,primarily at low and mediumfrequencies. It seriously affects thelong and medium wave reception ofradio transmissions and will also bepicked up by audio equipment, whenit is heard as a raucous buzz. This rfican also interfere with laboratoryapparatus, especially pH meters, andhas been known to cause erraticoperation of digital computers andother equipment.

The radiated energy can be reducedby including an rf choke in series withthe power line (shown as L1 in circuitsaccompanying this article). A suitablechoke can be made by winding 40 to50 turns of enamelled copper wirearound a piece of ferrite aerial rod.This will provide an inductance ofapprox. 100 pH. For greatersuppression it will be necessary toincrease the inductance to as much as

O

5k

Load

A/C I I

5k

5k

10M'Gain'

100k

- 0.1µf

1k

Fig. 26 This circuit provides proportional control of heating loads.

5 pH, and this neccessitates a full-sizechoke.

The limitation of this type of circuitis that the rf choke has to carry thefull load current, and once thisexceeds a kilowatt or two, the physicalsize of the choke becomes excessive.The larger the load, the more difficultand expensive it becomes to filter outthe rf components. (The problem is

not as acute for inductive loads such aselectric motors, where the load itselfattenuates the rfi).

Phase control also introduces anotherproblem - namely the load powerfactor. This is adversely affected and issomething that power supplyauthorities regard' with less thanequanimity.

ZERO VOLTAGE SWITCHINGVirtually total freedom from rfi can

be achieved by a Triac control systemknown as zero voltage switching.

This system differs from phasecontrol in that line voltage is switched'on' as well as 'off' only at the zerocrossing points of the sinusoidalwaveform. The power applied to the

Fig. 27

Zero voltage switching waveform - power is controlled by varying the ratio of completehalf -cycles 'on' to complete half -cycles 'off.

load is controlled by varying the ratioof time that power is applied, to thetime that power is switched off. Forexample, if only a small amount ofpower is required, the Triac is causedto pass just a few complete half -cycles,then remain switched off for a further30 or 40 complete half -cycles beforerepeating the sequence (Fig. 27).

It will be apparent that the zerovoltage switching system can only beused to control loads that haveconsiderable inertia, such as heatingelements which by their nature willaverage out the bursts of energy. Zerovoltage switching cannot be used forcontrolling lighting or motor speed.

Load power factor is not affected inany way by zero voltage switching.

Until recently the drawback to zerovoltage switching was that thetechnique required a large number ofcomponents.Fortunately the functions necessary

for zero voltage switching have beenmade available in an integrated circuit- and, by using this specialized ic,zero voltage switching circuits can bebuilt that are outwardly no morecomplex than their phase controlequivalents.A full description of zero voltage

switching techniques will form Part IIlof this article, to be published nextmonth.


Hams AtMississauga MadnessMike Goldstein, VE3GFN, has this dramatic story of the critical roleof radio hams after the Mississauga derailment.

IT ISAQUIETSATURDAYevening inMississauga, on the West side ofToronto. The hour approaches mid-night, as a freight train loaded withchemicals speeds through an industrialarea near Lake Ontario.

Moments later, the train, derailed, is atwisted wreck, and flames are reachingas high as an apartment building. KenAdams, VE3BEA, calls his wife to thewindow of their Oakville home toobserve the glow of "aurora" in theEastern sky ... strange for this time ofyear. Their house shakes, as tanks ofpropane begin to explode, and Kenrealises that he is not seeing aurora.The Mississauga madness has begun.

DEADLY CHLORINEBy early Sunday morning, officials

have realised that the train containstanks highly toxicbegin evacuating the immediate area ofthe wreck. Chlorine gas was used withdeadly effect in World War One, and it isnow leaking into the air in a populatedcity. The large shopping plaza knownas "Square One" becomes an evacua-tion center.

\I\iadio amateurs across the Torontoarea have been discussing the situationfor hours, their radio systems coveringhundreds of square miles. They beginpreparations or emergency communi-cations, for which ham radio has a 70 -year tradition. The "Amateur RadioEmergency Service", a continent -wideorganization, exists for this purpose,and has active branches betweenOshawa and Hamilton. The coordina-tors begin contacting officials to offertheir services.

George Jones, emergency plannerfor the Ontario Hospital Association, ispulled from his bed by a phone call. Theamateurs have worked for Georgebefore.

Mississauga Hospital is evacuated.Rick, VE3IFI, is sent to the area of the

accident to see if amateur radio isneeded, with instructions not to getunderfoot. All roads are blocked in thearea. There are Red Cross people onsite who need communications, butthey cannot be reached, and Rickcannot get past the barricades.

Rick is trapped in Square One Plaza,

Leon Giannakeff, VE3BUI, Reg Martin, VE3DHO, and Ted Dubois, VE3HO1, providecommunications for the Red Cross on November 14, three days after the derailment.

as that evacuation center is itselfevacuated. It is now almost noon.People living on the banks on the CreditRiver are warned they may have to beevacuated.

COORDINATIONHoward Johnston, VE3ITN, calls byradio from Oakville He is EmergencyCoordinator for that area, and offers hispeople if needed. Two days later,Howard will be manning his ownevacuation centers, as the danger areastill spreads.

Aldo Galati, VE3IMR, calls fromOshawa, another Emergency Coordin-ator. It is a long drive from Oshawa toMississauga; Aldo and his people willbe there.

Peter Schuyffler, VE3JPP, checks infor the Pickering Radio Club, anemergency minded group. Peter is anassistant EC with the EmergencyService.

Charlie Powers is a Gulf executivefrom Oakville, who doubles as theoverall Emergency Coordinator for allof Ontario. Operating his stationVE3APK, he is in contact with Burling-ton, Guelph, Brampton, and otherareas. Chuck has recently made anagreement with the Red Cross, and hecontacts them now.

Qeensway General Hospital is evac-uated.

The afternoon wanes, and no officialshave requested our assistance. Theamateurs resist the temptation todescend in force on the area, andpatiently wait by their telephones.

Interest and enthusiasm begin tofade. We have trained for twenty yearsto correct the problems of HurricaneHazel, but we are not called. Incredible,but true.

The evacuation area widens, as thewind shifts. Eventually, the entirepopulation of the city of Mississauga, aquarter of a million people, will beevacuated.

At 7:30 p.m. on Sunday, we receivethe word. The Red Cross requirecommunications between all evacua-tion centers, and have discovered thelimitations of the telephone.

HAMS TO THE RESCUE!As Emergency Coordinator for

Toronto area, I must set up a station atRed Cross headquarters in downtownToronto. Peter, VE3JPP, is sent to dothis, with assistance from the PickeringClub. He will not emerge from thebuilding at Jarvis and Wellesley for 3days.

Rod Pears, VE3I XB, is the brand new


Emergency Coordinator for the evacu-ation area. This operation becomes hisbaby, and he is already manningevacuation centers at Streetsville,Brampton and Malton. The ink is barelydry on his EC certificate - what aninitiation! We agree that I will back himup with manpower from Toronto, andcover downtown Red Cross. Together,we begin making up the first of manyrosters that will have ham operators atemergency stations around the clock.

There is talk of evacuating Oakvilleand Streetsville. Oakville Hospital isevacuated. The firescontinueto burn. Itis decided to let the fi res burn out, ratherthan try to contain the large amount ofpropane that is fueling it.

"THIS IS VE3HRU, NET CONTROL.ALL STATIONS CHECK IN".

This is Stan, operating as controlstation for a radio network that includesall evacuation centers, Red Crossheadquarters, and even the accidentsite. Operation is on the Brampton"repeater", one of a dozen automaticrepeater stations in the Toronto areathat allow city - wide coverage byradio, using low -powered VHF trans-ceivers. Other repeaters will be usedfor message handling, leaving theBrampton repeater for control pur-poses. The Toronto Police have asimilar repeater system, but theirrepeaters were not built by the users, asours are.

"VE3SPC AT RED CROSS HEAD-QUARTERS, SORRY, WE HAVE NOFURTHER SOURCES OF BLANKETS.PLEASE ADVISE YOUR NEEDS, ANDWE WILL SEE WHAT WE CAN FIND..."

Lyle Stanway, VE3DLS, has nothingto do. Leaving his Downsview home, heeventually finds himself at CFB Downs-view,where he locates 25000 blankets,and the army transport to move them.Another problem solved.

The International Centre at Malton isopened as an evacuation center, andVE3HKN and VE3HHAare sentto set upa radio link. Erindale Public School,another evacuation center, is evacua-ted, and VE3FEH and VE3IAC movewest, to set up again.

Some people have now been evacu-ated three times.

BARRICADE PROBLEMSLawry Purdy, VE3FPF, has reached

the accident site, at Eglinton and MavisRoad. Suddenly, Red Cross find theyhave a direct line to the people settingup evacuation and transport. The site isassigned a priority, and will be mannedthroughout the operation. Of course noarrangements to clear radio hamsthrough police barricades have been

made, and each relief operator must benegotiated into the area by the on -siteoperator. The lessons of Hazel have notbeen learned by city officials

Bob, VE3GOY, and Paul, VE3GPB,drive from Red Cross Headquarters toStreetsville to the accident site, tryingto obtain advance clearance, to noavail. They eventually get past thebarricades, and Lawry goes wearilyhome to find his house evacuated. Heoperates henceforth from the Burling-ton area.

MONDAYIt is now bleary Monday. I have had

four hours of sleep, much more thanmany others. There is a new rosterto bemade up, and I go back to thetelephone. Calling friends at 2:00 a.m.does no good; you must call them at6:30 a.m., just as they are rising, anddivert them from work. Many wives hateme.

VE3IXB, aided by Roger, VE3HGC, isgoing strong, and we soon have aroster. VE3GBC is now net control onthe Brampton repeater. Bill Cosburn,VE3BUU, with VE3DDU, are at theaccident site.The evacuation area widens further.

"THIS IS VE3SPC AT RED CROSS.WE NEED A HEAD COUNT OF EVAC-UEES AT ALL CENTERS ..."

Peter Schuyffler's Dutch accents arebecoming a trademark of this opera-tion. Although relief operators arebeing supplied at Red Cross Peterstayson to help. He is one of many who willdrive themselves to exhaustion, freeingup other operators for duties else-where.

"THIS IS WESTHEAD FOR TOMHUNTLEY AT THE SITE. I WANT TOKNOW PRESENT EVACUATION STA-TUS RIGHT AWAY. OVER"

General Jim Westhead is running theshow at Red Cross headquarters. He isthe chairman of Emergency Servicesfor the Red Cross Ontario Division, andhe is constantly updated by radioregarding the needs of his evacuationcenters. His microphone techniqueimproves constantly asthe time passes,

The International Center, one of manyrefugee centers during the emergency.

and his voice becomes hoarse. An ironman, he is always there.

Sheridan College in Brampton be-comes an evacuation center; DonBrowning, VE3CBA is operating there,with VE3CNZ. They will be spending along night before being relieved.

MISSING PERSONSStreetsville Secondary School re-

ports a missing person, a diabetic whowas evacuated without his insulin. Hemust be found.

He is found. Some of these messagesare literally life and death.

Missing persons traffic becomes abig part of this operation, as familiesareseparated. A report regarding a party ofstudents returning from a trip, andscheduled as having landed at MaltonAirport, comes through. They must belocated, but only the name of theteacher accompanying them is avail-able. Not much information to go on,but the search begins.

The day wears on, the message trafficincreases. The media try to get detailsfrom the Red Cross operator, but he istoo busy to talk to reporters. PeterAmes, VE3DSA, volunteers as a P.R.committee of one. Pete is not well, andcannot operate for long periods, but hewants to help. He keeps radio andnewspaper people updated, and out ofthe confusion.

Time for another roster change; bynow, radio hams are calling me from allover the city, offering their help. Thelists of available people quickly fill, aseveryone comes home from work. Weare using 20-30 people for each shift,and changing shifts every 6-8 hours ...

or trying to: some people just won't gohome.

GOOD DISCIPLINEThe Burlington and Hamilton boys

have their own operation going now, asevacuees begin to enter those areas.We all keep in touch by radio, and littleduplication of effort takes place.

We have now been tying up hamcircuits and frequencies for about 36hours, with emergency communica-tions. Since only one station can talk on aFM repeater at any time, it is extremelyeasy to foul up a complete system.However, little if any deliberate inter-ference takes place, few stations pesternet controls with trivial requests, andnot a single complaint about busychannels is heard. Each of theserepeater stations is used by literallyhundreds of ham stations: for avolunteer service, it is amazing selfdiscipline. It is also what we are used to,and thus what we expect.


QRM

MONDAY NIGHTRod and I start on the midnight

rosters. It is getting tougher to findpeople, and I call on the Oshawacontingent, still waiting in the wings.Aldo, VE3IMR, finds some operators,and they begin the trek to Streetsville.Chuck Powers is talking to Guelph andKitchener, and Rod is waking up hiscrews for "recycling". The Georgetownand Brampton area hams are givingRod terrific support.

The Pickering crew is manning theRed Cross station, and they keepdriving back and forth between Torontoand Pickering. It is quite an effort for asmall club. They will need help onlyafter Tuesday morning.

On Monday night I take the phone offthe hook after filling my roster, and goto bed. It looks like it is winding down;but on Tuesday morning we are offagain, and another roster starts to fill.

Jack Argyle, VE3IDB, comes in fromBarrie, and starts making 'phone callsfor me. Ted Dubois, VE3HOI, isoperating for the second time, in fromNewmarket. Open heart surgery a fewyears back, (when hams lined uptogiveblood for Ted) has not slowed himdown.

"VE3PRC IS NET CONTROL. WHOIS NEXT?"

Noreen Nimmons, VE3GOL, is oper-ating as VE3PRC. A very smoothoperator, and an experienced messagehandler. Noreen came back from a busyweekend at Newington, Connecticut,attending meetings at the AmericanRadio Relay League - the "boss" of theEmergency Service. I caught her as shecame in the door. Noreen claims thatcivic emergencies are easy, afterraising teenagers. She will operate asnet control, with little relief, for thewhole of Tuesday, and much ofWednesday.

Jack, VE3I DB, leaves my basement togo to Red Cross headquarters, wherethey now use 5 operators for each shift.

The Moose Lodge Hall in NewToronto has been operating for sometime as an evacuation center. SheridanCollege in Oakville is serving a similarpurpose. The Vic Johnston Arena inStreetsville has been a busy place formany hours. All must be provided withamateur radio operators. As each shiftchanges, the station equipment andantennasforeach station isdismantled,and a new station is set up by the newoperator. This is not as difficult as itsounds; changeover takes about tenminutes. Radio hams are quite used toarriving with a car full of equipmentandcables, and "talking to the world" byradio shortly thereafter...

TORONTORED CROSS

HO, JARVIS &WELLESLEY

INTERNATIONALCENTERMALTON

STREETSVILLESECONDARY

SCHOOL

VE3SPC

VE3HOI

VE3KXF

NET JS TURNER BRAMPTONVE3 VE3 VE3CONTROL GBC SCHOOL FOA CENTENNIAL EBC

SCHOOL

DOLPHINPUBLIC SCHOOL VE3 WESTWOOD VE3 SHERIDAN VE3STREETSVILLE FSI SECONDARY HDH COLLEGE AKO

SCHOOL BRAMPTON

VICJOHNSTON VE3 ACCIDENT VE3

ARENA DLW SITE BUU

STREETSVILLE

MORNINGSTAR VE3HIGH SCHOOL MDL

VE3TOR

VE3MHZ

VE3TTY

VE3SKY

VE3MOT

VE3RSB

VE3DRW

AUTOMATIC REPEATER STATIONS IN USE

The emergency network, November 12, 8AM to 6PM.

We are now running a 12 -stationnetwork, and a minimum of 25amateursmust be found for each shift change.The operation has run for almost 48hours since we were called, and the listsof available "warm bodies" are becom-ing shorter and shorter. As peoplebecome tired, and less experiencedoperators must be used, the operatingprocedures begin to slip, and thenumber of mistakes made becomes ahindrance to efficiency. This is un-avoidable in a long operation, and is asign that we are approaching the limitsof our resources.

TUESDAY EVENING AL-READY

By Tuesday evening, the scope of theoperation has crested. The first tenta-tive indications of a return home byevacuees have appeared. Some evac-uation centers have closed, theirremaining people and supplies movedto other centers; now we are assisting intransport problems. Finding out whoneeds a bus, and trying to minimisevehicle traffic.

.. RED CROSS ADVI SE THAT YOUOPEN YOUR HOUSE WINDOWSWHEN YOU RETURN. OBEY ALLPOLICE DIRECTIONS. RETURN ON-LY TO AREAS SPECIFIED AS SAFE.DO NOT ATTEMPT TO BYPASSBARRICADES ..."

Carl, VE3FDL, and Al, VE3LF, leaveafter dinner for the Vic Johnston Arena.Ken, VE3BZV, heads off with VE3LCXfor the accident site. VE3GAW goes to

the Dolphin Public School; when itcloses, John shifts to the Arena. We arereaching the point where one operatorwill suffice, and our roster require-ments have dropped to a third. Thepressure is off.

It is reported that one operator issitting with a Red Cross man, justwaiting for blankets to be picked up; allevacuees have left. The coordinatorsagree that the emergency is over, and itis time to withdraw. We have littlechoice, for we have run out of resources... and we must not drag itontothe pointwhere our people no longer feel useful.Radio traffic begins to drop as midnightapproaches.

... INTO WEDNESDAYBy Wednesday morning, many evac-

uees are home. The control channel isactive, but carries little traffic. The radiocircuits will continue through the day,but will not be renewed as operatorscomplete their shift.

"VE3HO1 FROM VE3SPC AT REDCROSS. PLEASE INITIATE A HEADCOUNT OF EVACUEES AT YOURLOCATION AS SOON AS THEY AREALL AWAKE."

THIS IS VE3HO1. PLEASE ADVISERED CROSS THAT SLEEPING HEADSCAN BE COUNTED JUSTAS EASILY."

Now, it is time to examine why ithappened, and to try to prevent it fromhappening again. The miracle of nocasualties may not be repeated next

continued on page 50


L _

Circuits from ourreaders.

WIRE TRACERM.Feiffer,Kanata, Ont.Two quick ideas that can save the

day in certain cases.LED's can be used to trace two or

more wires of the same colour. Whenthe LED lights up, its anode is matchedto the positive lead of the battery.You can also substitute a diode inseries with a buzzer for audible ind-ication. In this case, drop the resistorand increase the applied voltage forreliable operation.Another quick idea is to use double

sided tape your work bench asa third hand to hold down loose tran-sistors, IC's and so on so they can beeasily checked with test probes.

, I-~,-- E-_WIRE 1 WIRE 2WIRE 1 WIRE 2

WIRE 1 WIRE 2

WIRE 1 WIRE 2

WIRE 1 WIRE 2

-14+xX

WIRE 1

+ -X

1,-N OR

WIRE 2

TTL LOGIC PROBEJohn Sloan C.E.T.Although there has been no shortageof logic probe designs in recent times,perhaps some people will find this thedual threshold probe interesting.

Referring to Fig. 1. three of fourcomparators in a LM339 quad packageare used to indicate the presence ofthree different input voltage levels.Resistors R1,R2 and R3 form a vol-tage divider so that if the input vol-tage is greater than 3.0V the outputof IC1A is low, turning on the "HIGH"LED indicator. A voltage less than0.8V turns IC1 B on, and a voltageanywhere between these two limits(a float) means the inverting inputof IC1C can go high, and the "FLOAT"LED is lit. Oscillations are detectedby both the "HIGH" and "LOW"indicators being on at the same time.Naturally, changing the resistors in

the voltage divider network will yieldany threshold levels desiréd, and thewide operating range of the LM339(VCC maximum is 36V) means theprobe can be used for more than justTTL levels.

46

IC1-LM339 Quad ComparatorD1, D2, D3 - any suitable LEDD4, D5 - any switching diodes

clip to circuit being probed

suggestedIndicator Layout

HI

osc Q LoL0 FLT

GND

clip to circuit being probed

R1 -20kR2 -22kR3 -8k2R4,R5,R6-680RR7 -10k


PING-PONG SWITCHESMichael Black,Montreal, Quebec.

This device is connected betweenthe output of an electronic musicalinstrument and the inputs of a stereoamplifier. It switches the input signalalternately between the two outputs.If the speakers connected to the amp-lifier are placed at opposite ends ofa room, it sounds like the signal is

bouncing from one wall to the other.When there is no voltage on pin 6

of the LM370 the input signal is amp-lified and passed onto the output.The 555 is the clock which determinesthe rate of the switching. The 7474divides the clock frequency by twoand assures that the duty cycle of theLM370 s is 50%.Adjustment is very simple. Connect

the input to the signal source andconnect the outputs to the stereoamplifier. Adjust R1 for no distortionon the output. The switching ratecan be adjusted by turning the potmarked 'rate'.

A.F.input

Rate

Note: LM370 pin connections are for the DIP.

SIMPLE CURRENT LIMITERC.FoxVancouver, B.C.This circuit is basically a common

collector amplifier with the basedrive for the transistor going througha 5k potentiometer. The pot is usedto vary the cut-off current and withthe components shown it is var-iable from about 5ma to 500ma.As you can see from the graph

above the cutoff is not particularlysteep but it should be enough tosave your power supply in case ofaccidental short circuit or to protectproto-type circuits from excess curr-ents while being tested.

Note however that current gain varieswith temperature of the transistor,so the transistor should be mountedon a heatsink, or other allowancesmade.

IN

100%

VOLTAGE

0%

I CUT OFF

CURRENT

2N3054 OUT


ervice ¿iU!i,; 5..9 7I ¡de ! ,o. 4o bo ,a !I4i ; o °0 oic 3O yh. o: C ryye a¡ 6jo, r ogaob ,p,?s;)br4ó , %'15a/ ryy0¡ To 4

41,pye oc4

4'>áfv,, ,Ao.. C;01, 00

located to serve the community. Theyprovide courses in both electronic andmajor appliance servicing. Enrollmentcosts are reasonable and the quality oftraining is excellent. Then there areseminars and workshops conducted byproduct manufacturers and distribu-tors. These are not complete trainingprogrammes but rather an update onthat manufacturer's latest designs.They give a good technical explanationof the circuit functions and trouble-shooting techniques. And last but by nomeans least, the home study school.RHC: As General Manager of the

Canadian Electronic & ApplianceService Association, just what are youtrying to accomplish?BILL: The Canadian Electronic &

Appliance Service Association (CEASAfor short) was founded by electronicand major appliance manufacturers,retailers and importers for the purposeof improving the quality of service in themarketplace and to improve the imageof service in the eyes of the consumer.Starting off in May 1977 with 14members, CEASA now boasts 21members, including 3 Provincial Ser-vice Associations. Our main objective isto help the servicer better himself andhis customer. To this end, CEASA hasbeen working with community collegesacross Canada to develop upgradingcourses in subjects such as MicrowaveOven Servicing, Business Managementand Electronics in Appliances. LastSeptember, CEASA introduced itsPlanned Protection Programmes forthe Canadian. Service Industry. Theseprogrammes, which are available toservice businesses and technicianswho are members of Provincial ServiceAssociations affiliated with CEASA,provide, at favourable group rates,Income Protection Insurance, Family,Life and Accident Insurance, IncomeTax Sheltered Investment and Retire -

This month Dick Cartwright interviews Bill White,General Manager of CEASA.

I recently had the opportunity tointerview Bill White, General Managerof the Canadian Electronic &ApplianceService Association, about manysubjects of interest to the Canadianservicer. I chose Bill for this interview asI know he has been directly involvedwith the service industry for some 40years, and with the exception of myself Iknow of no other individual who hasbeen actively engaged in our particularindustry for so long. The following ispart of that interview.

RHC In your daily contacts withservice technicians and service bus-inesses, what factors contribute mostoften to a successful service operation?BILL: Well, Dick, the service business,

as you know, is made up of so manyrelated parts it is difficult to single outone item as being the most important tosuccess. Knowledge of the productsyou service, knowledge of businessfundamentals, knowledge of the con-sumer needs are all very basic. Publicrelations and the ability to relate topeople are essential also. The bestadvice is - believe in yourself, respectthe consumer and have an ideal that isrealistic, then work like a beaver toachieve your goal.

RHC: From the factors you mention-ed, I assume that knowledge ranks highon the list of ingredients essential tosuccess in the service business!BILL: Yes, I would say so! Withoutknowledge you have little to work with!But knowledge to be useful must be up-to-date. Yesterday's training isn't goodenough in the servicing of today'sproducts.RHC: What l understand you tosayis

that technicians, to make it in today'sservice business, must have training oncurrent product designs.BILL: Yes. Training on current elec-tronic and major appliance products ismost essential for several reasons. The

consumer invests more money intoday's products, consumer circuitryhas a high profile in electronic productsand is coming into appliance designs. Aservice technician, to make it today,must have a knowledge of micro-processor functions, using solid statecircuits and components. Gone are thedays when you could pull and substi-tute questionable assemblies. Gone arethe days of the VOM for testingmodern circuits.You just can't get bywith the "trial and error" method ofservicing. Today you have to be able totroubleshoot circuit faults to a satisfac-tory conclusion.

RHC: Changing the subject, I under-stand there is a drop in the number ofservice calls on TV receivers and, if thistrend continues, there will, nodoubt, bea surplus of TV technicians. With thisprospect, do you foresee the day whenTV technicians will be endangeredspecies?BILL: Endangered species - no. Asurplus of TV technicians - well thatcould happen but I don't foresee it. It'strue that the introduction of solid statecircuitry to colour TV reduced theaverage incidence of service from 1.6 to0.4 calls per year. Reliability soared andservice took a nosedive. However, thedrop in TV service was offset to someextent by the demand for other productservice, such as Hi Fi audio, CB, etc.And by the mid 1980's, electroniccontrols will be common in majorappliances, such as automatic washersand dryers. These developments willtend to replace the drop in TV servicedemand.

RHC: How would you suggest theservice technician go about updatinghis technical knowledge?BILL: One of the best places to updatetechnical knowledge and skills is thelocal community college. Every pro-vince has several colleges strategically


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RHC: How about the consumer - IsCEASA interested in his needs?BILL: As I mentioned before, one ofthe aims of CEASA is to improve thequality and image of service in themarketplace. To do this we mustdevelop a good consumer relationsprogramme so the consu mercan betterunderstand what the service industry isdoing for him. To accomplish thisobjective, we have taken several stepsthat directly relate to the consumer. Forexample, we introduced a consumercomplaint -handling programme calledRSVP. Any consumer with a complaintagainst a Canadian electronic or majorappliance servicer can use the RSVPprogramme to air the problem andobtain a resolution of his case. CEASAkeeps the Ministers of ConsumerRelations in the ten provinces and theFederal Ministry of Consumer andCorporate Affairs as well as BetterBusiness Bureaus, Consumer Associa-tion of Canada offices and otherconsumer action groups, updated onthe latest service promotions availableto the consumer. For example, early inthe New Year, CEASA plans to an-nounce its registered identificationlogo. This Logo will then appear on all

materials issued by CEASA. Threeconsumer help booklets will also bereleased in the New Year for distribu-tion to the Canadian consumer byconsumer action groups and theindividual services.RHC: What do you foresee in the

future for the Canadian Electronic andMajor Appliance Service Industry?BILL: Growth is the most dominantfactor in the future of the industry. In1978, Canadian service businessesgrossed over $400 million. We areforecasting a doubling of annual grossrevenue in the next five years. Do yourealize, Dick, that within five yearsCanadian electronic and major ap-pliance service will be a $1 billionbusiness? It's hard to believe but thetrend figures point that way! Is it anywonder that the CEASA Board ofDirectors have pulled out "all the stops"to assist the Canadian servicer toupdate his knowledge and relate moreclosely with one another throughProvincial Service Associations.

RHC: I'm sure we could spendanother hour discussing the presentand future plans for the Canadianservice industry but ti me doesn't permitthat luxury. However, before I go wouldyou care to give any advice to ourreaders - many of whom are in theservice business?BILL: Yes, Dick, at the expense ofsounding like a broken record, I cannot

repeat too often that service is bigbusiness. There is a great future forgood servicers in electronic and majorappliance service. That knowledgeofproduct designs and the latest servic-ing techniques is the keyto success andcaring for the consumer pays off in richrewards.

Well there you have it from theGeneral Manager of CEASA, an asso-ciation that is fast becoming thespokesman for Canadian servicebusinesses to industry, consumers andgovernment. For over 30 years I havelooked forward to the time when allservicemen, both industrial and dome-stic, would be members of associa-tions, or even one national association,that would be in the position not only tolook after them but also to protect theconsumer.

So, to all practising electronictechnicians, take an old pro's adviceand join your local association. If youdon't have one, form one. Advice,knowhow, etc., on how to form anassociation are readily available fromCEASA. The advantages, as I havestated so many times before, are notonly technical and political, but thesocial benefits ensuing are well worththe little time and effort involved.

Wishing all our readers a very Happyand Prosperous New Year.

All the best.

Richard H. Cartwright.

continued from page 45

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RADIOGRAM DATED NOVEMBER 15,0045 UTCFROM: CANADIAN RED CROSSONTARIO DIVISION CANADIAN REDCROSS WISH TO EXTEND THEIRSINCERE APPRECIATION AND AD-MIRATION FOR THE SUPPORT GIV-EN TO THE SOCIETY DURING THEMISSISSAUGA EVACUATION CRISISSTOP THE HIGH DEGREE OF DED-ICATION AND PROFESSIONAL

DEDICATION AND PROFESSIONALSKILL EVIDENCED BY ALL -PERSONNEL OF AMERICAN RADIORELAY LEAGUE ONTARIO SECTIONIS DESERVING OF THE HIGHESTPRAISE STOP AS OF 2359 LOCALTIME 14 NOVEMBER 1979 THE OP-ERATIONS REQUIRING THE SER-VICES OF ARRL ONTARIO SECTION

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HUNGRY EYE

DUNGEON VIDEO .. . the pusuit of allpoor and demented troglodytes with acouple of somewhat antiquated VTRstucked unobtrusively away in the backof thefamilycave, behind the mastodonskulls, several extras wires running intothe rear of the communal 1959 Marconiconsole,and a peculiar, Byzantine

the thatch to pullin sporadic skip from L.A it's all,usually, something the average Nean-derthal gets into sideways. You comeacross a large electronic thing in asecond hand shoppe bedecked with asign reading "Device with knobs.$10.00 U Muv it". Alternately, the officedecides to upgrade the AV works, andsomeone presents the unresistableoffer (buy this or you're fired). Inappreciation for bringing the childrenover to visit, and eliminating any furtherconcern with her prize winning Bohem-ian carniverous orchids. Aunt Remorawants to give you whatever it was thatfinally drove Uncle Frankephobe intothe big aquarium in the hall. Somebodyleaves a one hundred pound foundlingon the doorstep.

Alternately, there are a few fortunatesouls who have become fabulously wellto do over the years, and, havingalready taken six tropical vacationsthisseason, have chosen tosinksomeofthefamily fortune into one of the newerhome video systems, the ever present,over priced video cassette recorders.These illustrious Members of Parlia-ment, while arriving at the objective ofvideo mobility with a bit more savoirfaire than the poor wretch of aparagraph ago, (although their savoirfaire is only worth about eighty fivepercent of some other, more southerlysavoir faire,) are in largely the same

WHAT'SON

You've got your home video system all set up, but nocamera. Steve Rimmer tells you what to do.

Lion in terms of equipment capabi-??ties and limitations.

For, you see, friend Neanderthal,while video tape recorders are fairlyeasy to come by surplus, or justify new,there are other odd scraps of hardwarethat are a bit more elusive. Chief amongthese is the mighty TV camera, themedium by which your very own livingroom can beturned into a video studio... without necessarily telling the occu-pants. Old cameras get the boot far lessfrequently than do old recorders. Thestate of the art for cameras is such thatobsolescence overtakes them at arather more dignified rate. New cam-eras, at least those offered for sale in theconsumer market, are, as a lot, ratherdismal, especially in light of the pricesbeing asked for them. Therefore, awhole area of potential for basementvideo goes unexplored for manyowners of video recorders.

Will we stand for this? Is such a grossinjustice to be tolerated? Are thetechnological fruits of our society to bewitheld from the másses? Alright, whosaid "Yes"?

This month, we're going to have anextended look into the different waysaround aquiring a television camera forhome use without having to sell off thehome to do it.

GENERICALLY SPEAKINGThere are, essentially, two types of TVcameras, studio cameras, which pro-duce the pictures one sees on the box,and surveillance cameras, whichproduce the pictures many securityguards see simultaneously on eighteenboxes. The former type are somewhathuge, very expensive, and producesreally marvellous pictures. They havebuilt in CRT monitors, so that thecamera person can see what the lens

sees, rear mounted controls for zoomand focus, great resolution, and a highdegree of control of the grey scale overtheir, albeit limited, contrast ranges.This comes, in part, as a result of theirbeing fairly insensitive to light, thusrequiring high scene illumination togettheir tubes going. It is highly unlikelythat any of us are ever going to own one,so we won't bother with these things.

Surveillance cameras are the otherend of the spectrum. They are relativelyinexpensive, small, and really quitesimple. They are very sensitive to light,but aren't all that linear with it once theyfind some. They have no rear mountedzoom controls because they don't havezooms, and focussing is usually done inthe conventional manner, up at thefront. They don't have built in monitors,or, in fact, any viewfinders at all,because mounted up on the corner ofan office building somewhere, the onlycamera man the average surveillancecamera is likely to see is the fellow whocleans the lens twice a year.

There are several gradations bet-ween these two extremes, and, inhaving a quick scan among them, itseems that there are several classifi-cations of hungry eyes that could beused, or adapted, for the high and noblepurpose of feeding pictures of the catinto a surplus VTR. In allcases,thismayalso be read as directing images of thefamily Albanian ocelot into a rhines-tone encrusted RCA 400, dependingupon whether of not that little dodgewith the income tax got through or not.Cameras used in telecinis, that is, totransfer films to video tape, small, cableTV studio cameras, educational cam-eras, industrial process monitor cam-eras, microscope cameras, and AVcameras are all among the typessuitable for providing video for your


What's Onbox. When stumbled upon in a surplusstate, all are available quite cheaply ...

say in the range of fifty to one hundredand fifty dollars, and, in most areas,cameras in this icategory are prettycommon on the back shelves of videodealers, industrial systems suppliers,and electronic surplus gnomes.

The camera in figure one, a PHILIPSEL 8000/12, is a good example of thistype of beast. Although its manual doesnot state specifically what it wasoriginally intended for, it seems to besuitable for any one of a number of theabove applications,or simply as asurveillance instrument. Built in the midsixties, it is almost all solid state (twotubes, including the camera tube), andproduces pictures which are indistin-guishable from those coming over theairwaves ... except that they're blackand white. It cost a hundred dollars at aToronto area audio -video firm.

The camera is, in virtually all itsspecifications, quite superior to any ofthe commercial home monochromecameras, and, with a little work, can beinterfaced with any system.

TO BUILD OR NOT TO BUILDWay back last year, upon doing this

column on consumer cameras, I

thought it essential that a way be foundto come up with home video cameras atfairly humane prices. The first app-roach to this was going to be buildingone. As we've just seen, the circuitryinvolved is not particularly complex,and, with a few suitable IC's to do thetime bases and video amps, quite asimple camera could have been pro-duced. A variation on this theme was tohave a look at a camera kit. In theNovember issue, you may recall thatthekit survey included a bit on ATVResearch, which offers several camerakits, which, although a bit on theprimitive side, do produce quiteacceptable little boxes when complete.However, with both approaches, theresult was going to be up in the onehundred and fifty dollar range. Fur-thermore, vidicon tubes are, electrical-ly, extremely fragile. A lack of scanningvoltage, for instance, for even a briefperiod of time will ruin one. Thus, thecost of getting a home made designtogether seemed a bit prohibitive.

. The "re -roll yer own" surveillancecamera approach seems to be the mostcost effective. Although they tendtoward the obnoxious scuzzies, fiftybuck cameras are not at all scarce. Forup around a hundred, quite excellenthungry eyes are simply screaming atone from all directions. At one fifty,there are even a few viewfinder typesaround. Firms that deal with broadcast

Fig. 1 Philips EL8000 CCTV camera

video equipment, educational audio-visual supplies or surveillance systemswill all probably begin slobberinguncontrollably at your inquiry regar-ding a camera, as quite a number comein as rental returns, and they're usuallya bit swamped with them.

There are all sorts of things to checkout when considering a specificcamera. This isagood state of affairsforme, as, if there weren't, I'd have to endthis column here, and spend the rest ofthe space talking about video discs ..which by now we all know is quiteimpossible. So, in a way, it's really quitefortunate that there are so many thingsthat can be wrong with a camera.However, this isa highly literary point ofview, and you need not share it.

One of the fine things about buying acamera from a guy who spends his daysselling cameras is that there is no wayhe will not have a monitor available. Ifyou get a come on like "Listen. It worksreal good.lt's just that all our monitorswere swiped an hour ago by a tribe ofBedoin junkies." there probably aren'tany parts inside. Thus, the first thing todo is to feed the signal from the camerainto a monitor. Alternately,use a TV setand the camera's internal RF modula-tor, should it have one. While theresolution isn't as great with this latterapproach, it is a quick way to make surethat the modulator hasn't been sub-verted to the purpose of runningsomeone's TV game.

First, let's hope the camera producesa clean, stable picture on the picturetube of its associated television. Next,let's hope that the picture is of the samething that the lens is focussing on thevidicon faceplate. These two criteriahaving been met, we'll move on to thesubtleties.

Vidicon tubes cost between thirtyand fifty bucks, making them about themost expensive component in a cam-era. Thus, some pains should be takento check out the condition of the one inyours. If there is a distinct vertical orhorizontal line running through thecentre of the picture, the tube has beenrun without one or the other scanningvoltage at some time . .. which sort of

scarfs it up a bit, unless you happen tolike the line. An odd shaped blackblotch on the screen, having fairlysharp and regular edges, indicates thata piece of material from somewhereelse in the tube hasfallen ontothe photoconductive layer of the target. I am toldthat these things do become dislodgedfrom time to time, thus clearing up theproblem . .. but I've yet to see it come topass myself, so this sort of blemishshould also be considered fairlypermanent. If the cameraisfocussedona dimly lit scene, or the lens cap is stuckover the lens,an indistinct"blackerthanblack" blotch may be detected in thepicture. This indicates that the camerahas been trained on a bright light for anextended period of time somewherealong the line, thus burning the tube.However, as should be apparent,marginal burns only make themselvesknown under conditions of abysmalillumination, so you may find yourselfquite willing to live with one if it isn't toosevere.

Once a tube is installed, and it startsscanning, the faceplate gets burned in.Unlike an oscilloscope tube, there is noinherent orientation of a vidicon whennew. However, if the tube is used forawhile, and then rotated, whatevermargins of the original scanningprotrude into the new raster will bevisible as lines. These are fairlypermanent. If the tube is rotated back toits original position, a similar effect willtake place using the second scanningas seen over the first.

Like all tubes, vidicons do have finitelives. Unfortunately, the visible effect ofa dying camera tube, the inability toresolve clean whites, is very easilyconfused with several other things, likea misadjustment of the beam control. Ifyou suspect a vidicon of being a bitgeriatric, it might be wise to adjust thebeam and target potentials to see if thecondition persists.

Aside from the notable power trans-former frazz, hassles in the rest of thecamera, scanning non-linearities,video clipping or distortion, syncinstability, and so forth, are not reallymajor drawbacks, especially if the priceis right, because a half hour with asoldering iron and a scope will usuallyclear up any circuitry trolls that mighthave crept in in the dark. Probably theworst thing that can happen, in thisarea, would be a blown vidicon focuscoil or e price is right, because a halfhour with a soldering iron and a scopewill usually clear up any circuitry trollsthat might have crept in in the dark.Probably the worst thing that canhappen, in this area, would be a blown


What's On

vidicon focus coil or deflection yoke,but these things are pretty standard,and suitable replacement parts usuallyaren't hard to come by.

BEING LENS WARYThe things to be on the lookout for, at

the present time, is a curious pheno-menon known as the insidious Cos-micar lens switch. Now, Cosmicarlenses, at least, the ones in question(see figure 2) are very cheap; they costabout twenty bucks new. They'refound, for instance, on the front of theconsumer type monochrome cameras.However, they're really pretty terriblelenses for this application, having, asthey do, no irises and only the mostrudimentary of focussing mechanisms.They can be used in TV camerasbecause of the existence of ALCcircuitry to adjust the exposure,however, this limits the camerato useinfairly middle of the road lightingsituations.Since all TV cameras have the same

"C" thread mount (as do, in fact, most 16mm film cameras), these hairy little

Fig. 2 Beware the ultra cheapo Cosmicar lens.

brutes are mechanically interchange-able with whatever lens is supplied witha camera, which is, regardless ofmanufacture, bound to be a better trip.Inasmuch as these cameras costanywhere from five hundred to athousand dollars new, it is reasonableto suspect that a manufacturer wouldnot fit such an instrument with dimestore optics. In fact, to my knowledge,nobody building industrial camerasuses these things.

However, there are a few dealers whodo. Preying upon the weak, theignorant, the poor and humble scum ofthe Earth . . and anybody else with

money ... a few of these insidious cadshave taken to swapping the factoryinstalled lenses on second handcameras with Cosmi-cheaps. There-fore, be warned! Hark! Gadzooks, andlike that.

Probably the worst situation in theused camera scene is when you comeacross a hungry eye that's closed; nopicture. As far as an on the showroomfloor evaluation goes, there isn't verymuch that can be done. It is usually bestto assume that the vidicon is at leastpartially shot. It is also a good idea, ifyou're contemplating a surprise pack-age of this sort, to check out theinternals. Sometimes one will find someof the niceties of the system, such ascircuit boards, power supplies, deflec-tion coils or even the old tube itselfreduced to insignificance by their veryabsence. In no case should one paymore than about fifty dollars for atreasure such as this.

Next month we'll be talking abouthow to get your newly acquired olddecrepit video camera working. In themeantime stay tuned, keep clean, anddon't take any wooden Tories.

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54



A History Of Car IgnitionIan Sinclair takes the clouds of time (and exhaust) to the beginning of ignition,and sparks some interest on the way.

EVER SINCE the first motor car made its first coughingmovements, designers have had the problem of ignition.Perhap's that's what encouraged the development ofsteam cars for so long, it's worth remembering that theStanley Steamer held several speed records in its day,and was still being manufactured in the twenties.

The gas engine still works in the same way as as itthen. As the piston descends, a valve opens and lets themixture of gas vapour and air enter the cylinder. Atabout the end of this induction stroke, the valve closesand then the piston starts to rise, compressing themixture (compression stroke). Near the top end of itstravel, the mixture has to be fired- and that's the job ofthe ignition department. Firing the mixture is whatprovides the power, driving the piston down, andkeeping things going. At the next upward movement ofthe piston another valve opens, letting the exhaust gasesescape. This four-stroke scheme has survived pretty wellunaltered in principle, though with many improvementsin details. The ignition of the mixture is one of the ratherimportant details which has changed quite a lot since thefirst four stroke petrol engines were tried out.

PILOT FLAME IGNITION

The first gasoline engines used for ignition a schemewhich had been quite acceptable for large gas engines.A small hole is drilled at the top of the cylinder (into thecylinder -head) and a lamp flame is allowed to burn closeto the hole. This is easily done in a gas -engine by havinga pilot -jet burning near the hole.

On the compression stroke, mixture is driven out ofthe hole, meets the flame, ignites, and the burningmixture blows back through the hole to ignite the rest ofthe mixture. Primitive, certainly, but quite effective for alarge gas engine as long as you're not looking for highperformance. The main problem here is that much of themixture is lost, and it's very difficult to be sure thatignition won't be too soon.

HOT TUBES

For gasoline engines, this was soon replaced by hot -tube ignition. As the name suggests, the end of thecylinder -head was formed into the shape of a sealed tube

VALVES

HOTTUBE

Fig. 1. Diagram of theworkings of hot tubeignition.

the end of which was kept hot by a small blowlamp. Thetiming of the ignition still isn't under much control, butat least no mixture is lost, and the hot tube ignition wasused on a lot of famous cars of the veteran period (before1904).

Modern times start with electric ignition systems, andthere are still plenty of cars running around with elec-trical ignition systems which would have been familiar toa mechanic seventy years ago. Oddly enough, it's not allthat well understood so let's take a close look at it.

HIGHS AND LOWS

There are two parts to the ignition system, the LT andthe HT (sparks). The LT circuit consists of the contactbreaker and the primary winding of the ignition coil andthe HT of the secondary winding of the coil, the dis-tributor (which ensures that the spark goes to the correctplug) and the plugs themselves.

The contact breaker is a switch operated by a camwhich runs at half of engine speed and has as manybumps (lobes) on it as there are cylinders in the engine.The spark occurs just as the switch contacts (the points)open, so that we can alter the timing of the spark byrotating the switch assembly slightly.

When the contact points are closed, current flows inthe circuit through the primary of the coil and the points.The primary winding of the coil has a large inductance,and obeys exactly the same laws as any other largeinductance-if we want the current through the coil to


A History Of Car Ignition

o

IGNITIONSWITCH

RELAYCONTACTS

BALLASTRESISTOR

TODISTRIBUTOR

THE BALLAST RESISTOR ISSHORTED OUT WHILE THESTARTER MOTOR IS RUNNINGSO THAT A HIGHENERGYSPARK IS OBTAINED FORSTARTING

CONTACTBREAKER

Fig 2. Simple electrical ignition

charge rapidly we need a high voltage; if we cause thecurrent to charge rapidly, the coil will generate a veryhigh voltage.

MAKE A POINT OF IT

When the points close, the current through the coilincreases following the graph of Fig. 3. This time iscalled the dwell time, and the points must remain closedfor long enough to give the current time to reach its finalvalue. When the points open, the current is rapidlybroken, causing the coil to generate a high voltage pulsefrom the collapsing magnet field.

This high voltage pulse is then stepped up by thetransformer action of the secondary winding, givingabout 20-25 kV to send a good spark cracking across thegap of the spark plug - we hope.

With such a simple system the life of the points can berather short, and the spark at the plug low in voltagebecause of sparking at the points. The reason is that thevoltage pulse which occurs whenever the pointsseparate is enough to cause a spark at the points. Thiskeeps some current flowing in the coil, so that thechange is not so rapid as it should be. We can avoidthese problems to some extent by connecting a capacitor(they still call it a condenser in garages) across the

Fig 3. Graph of current through coil.

CURRENTIN COIL

DWELLTIME

NEXT OPENING' OF POINTS

POINTSCLOSE

TIME

points. When the points open, the voltage pulse pro-duced by the coil (Fig 4) starts charging the capacitor,giving the points time to open and so avoid the worst ofthe sparking. Because this also results in a more rapidcharge of current, the spark at the plugs is very muchbetter when a capacitor is used.

BAD POINTS

The whole system works very well indeed, and isremarkably reliable but suffers from two disadvantages.One is that a fast revving engine with a large number ofcylinders may not permit enough dwell time to allowcurrent to build up fully before the next opening of thepoints. The other problem is that there is still somesparking at the points, so that the contacts wear un-evenly and have to be reset at intervals, and ultimatelyreplaced.

Electronic ignition systems use the same coil and HTequipment, but a different method of obtaining a quickcharge of current through the coil. Most modern systems

Fig 4. Voltage pulseproduced when thepoints open.

POINTSOPEN

i

TIME

FREQUENCY DETERMINEDBY COIL INDUCTANCE

use capacitor discharge in which an inverter circuit isused to generate about 400 V DC to charge a capacitor.

When the points open the capacitor is dischargedthrough the primary winding of the coil, and this voltagepulse is stepped up by the transformer action of the coilto provide the high voltage from firing the plugs.Because the capacitor can be recharged quickly, thedwell time that is needed is reduced, and because thecontact points only have to cause a thyristor to fire, theyneed carry only a fairly small current and because theydo not carry current to the coil, there is no voltage pulseacross them.

The points still need periodic adjustment though,because the rubbing of the cam against the fibre pegwhich operates the points causes wear, altering the


A History Of Car Ignition

5kHz 400VDC

POINTOOS

OSCILLATOR TRANSFORMERRECTIFIER

Fig 5. Typical modern system.

SHORTS ClTO EARTH

THYRISTORSWITCH

ClCOILPRIMARY

400V PULSEWHEN THYRISTORIS FIRED

timing. To avoid such mechanical problems the cam canbe replaced with a slotted cover rotating around aninfra -red source (an LED), and so interrupting a beamwhich strikes a photocell. This then triggers the thyristor.Using this system, no adjustments are needed to com-pensate for mechanical wear until the gears on the shaftwhich drives the ignition system wear down-by whichtime the rest of the engine will have worn out anyway.

This is the system which enables car manufacturers tooffer five year guarantees, and to promise 100,000miles between adjustments of the ignition system.

POINT OF NO RETURN

Unfortunately, all this ingenuity does not ensurereliability, and electronic ignition systems have obtaineda very bad name for causing accidents. The mostcommon heart -stopper is that the ignition simplyceases-and if you're overtaking at the time it can befatal. The other is completely erratic timing, with theengine knocking horribly and the sparks happening atany old time in the cycle-I limped home several mileslike this once.

These problems can be solved, and car manufac-turers who have gone over to electronic ignition havesolved them. Nothing on earth, however, would persu-

Complete Ignition system. Note the position of critical components.

119 )

IS ON THE SAME CORE AS L1 & L2

_J

ade me to use an electronic ignition system unless eachcomponent was marked with a manufacturer's nameand the ratings. A lot of DIY systems seem to use BrandX components-and that's asking for trouble.

The components which are critical are the invertercircuit, the transformer for the inverter, the charge -discharge capacitor, and the thyristor itself Fig 6. Theinverter circuit must keep oscillating (though thefrequency may change) even as the thyristor fires,shortcircuiting the output of the transformer. This is, inturn, possible only if the transformer is correctly de-signed for the job.

The charge -discharge capacitor has to provide largepulses of current, and must be rated to take much morethan the normal 400 V to allow for surges. The thyristormust also be able to withstand the full voltage of theinverter, plus any surges, and to pass the pulses ofcurrent to the coil. A 1000 V 10 A thyristor may seemexcessive, but is very much more reliable than the usual600 V 1A component.

GOOD POINTS

Many exaggerated claims are made for electronicignition system, but the hard facts are that the mainadvantage is a longer time between ignition setting,particularly if the infra -red beam system is used. Coldstarting can be better but only if the inverter uses avoltage regulator, which is rather rare.

Against this, reliability may be less, unless the wholecircuit is built from top -grade military -specificationcomponents, rated to work at temperatures from wellbelow freezing (you want it to start in the winter) to nearboiling point (after it has stood out in the blazing sun forseveral hours).

However, there's little doubt that the well designedelectrcnic ignition systems now being designed into carsby the manufacturers are quite definitely up to the job,with very great reliability and freedom from adjustment.

flL3

BRIDGERECTIFIER

1~1\A",/0

+12VIGNITIONSWITCH

INPOINTS

o

oCOILPRIMARY

QOSCILLATOR

ET' CANADA-JANUARY 1980

RECTIFIER THYRISTOR

57

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N I BABAN I BABAN I BABAN I BABAN I BABAN I BABAN I BABAN I BABAN I BABAN I BABAN I BABAN I BABAN I BABAN I BAB,Electronics Pocket Books sped to you from

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Is electronics your interest? Then get into it more deeply in the special areas of your choice. ElectronicsToday carries a range of electronics books published by Babani Press and Bernards, amongst which arethose described below. (If someone has already used the card, write to Electronics Today Magazine, Unit 6,25 Ovérlea Blvd, Toronto, Ontario M4H 1B1)

Select from this collection of fascinating pocket hooks.

IC 555 Projects BP44 Every so often a device appears that is so useful than one wonders how lifewont on before without it. The 555 timer is such a device It was first manufactured by Signetics. but is now manufactured by almostevery semiconductor manufacturer and le inexpensive and very easilyobtainable.

Included in this book are Basic and General Circuits, Motor Car and ModelRailway Circuits. Alarms and Noise Makers as well as a section on the556.559 and 559 timers. An invaluable addition to the library of all those interested in Electronics.

$6.50 plus 30c postage and handling.

52 Projects Using IC741 BP24 IC741 is one of the most popular. inexpensive and easily obtainabledevices avaitable to the home constructor It is also extremely versatile andcan be used in a great number of various applications Thia unique book, originally published in Germany. shows fifty-twodifferent projects that can be simply constructed using Only the IC741 andsfew discrete components. An invaluable addition to the library of all those interested in electronics


Mobile Discotheque Handbook BP47 The cast majority of people who start up Mobile Discos" know very littleabout their equipment or even what to buy. Many people have wasted a"small fortune on poor, unnecessary or badly matched apparatus. The elm of this book is to give you enough information to enable you tohave a better understanding of many aspects of "disco" gear. The approach adopted is to assume the reader has no knowledge endstalls with the fundamentals. hopelullytheexplanationsgiven are !limpid ledenough for almost anyone to understand but please not that this is by nomeans the full story The book to divided into six parts - Basic Electricity, Audio. AncillaryEquipment. Cables end Plugs, Loudspeakers. Lighting Equipment and theinformation has been considerably sub -divided for quick and easyreference

$4.95 plus 30c postage and handling.28 Tested Transistor Projects No.221C Mr. Richard Tornns is n wr!l experienced electlunics developmentengineer and has designed. developed. built and tested the many useful endinteresting circuits included in this book. Some of the circuits are completely new and, to the best knowledge Of tieauthor, unlike anything previously published while others many bearsimilarity to more familiar designs. The projects themselves can be split down into simpler building blocks.which are shown separated by boxes in the circuits for ease of description.and also to enable any reader who wishes to combine boxes from differentprojects to realise Ideas o1 his own. Most of the circuits are very economical on the weal components and inmany cases the semiconductors employed are non -critical, commonlyavailable and Inexpensive types


First Book of Transistor Equivalents Bpiand Substitutes Shows snematives and equivalents to many popular transistors made inGreat Britain, U.S.A., Europe, Japan and Hong Kong etc. Companion Volume to BP14 - SECOND BOOK OF TRANSISTOREQUIVALENTS AND SUBSTITUTES An Invaluable addition to the library of all those interested in Electronics bethey amateur or professional.

$2.50 plus 30c postage and handling.Second Book of Transistor Equivalentsand Substitutes BP14 Shows alternatives and equivalents to many popular transistors made inGt. Britain. U S A., Europe. Japan and Hong Kong etc Companion Volume to BPI - FIRST BOOK OF TRANSISTOREQUIVALENTS AND SUBSTITUTES All invaluable addition tothe library of all those interested in Electronicsbethey amateur or professional


Radio Circuits Using IC's BP46 This book describes Integrated circuits and now they can be employed inreceivers for the reception of either amplitude or frequency modulatedsignals. The chapter on amplitude modulated (a.m.) receivers will beof mostinterest to those who wish to receive distant stations at only moderate audioquality. whilst the chapter on frequency modulation If m I receivers wiltappeal to those who desire high fidelity reception of local v,h.f stationsPossibly with stereo (and even quadraphony at acme future date). Stereodecoder circuits and the devices available at present for quadrophoniccircuits are discussed. Voltage regulator devices are also covered becausethey are ere convenient in all vericap tuned receivers and because they haveso many applications in all types of circuit. Brian Dance's a highly experienced author who regularly contributes tomany of the popular electronic magazines that are available both in the U.K.and overseas. An esdemely valuable addition to the libraryof ell Electrorticsenthuaiests.


50 (FET) Field Effect Transistor Projects BP39 Field et feet transistors IF.E.T.'si find application in a wide variety ofcircuits. The projects described here include radio Irequencyamplifierºandconverters. test equipment and receiver aids, tuners. receivers, mixers andtone controls, as well as venous miscellaneous devices which are useful inthe home. It will be found that in general the actual F.E.T used is not crIticaland manysuitable types will perform satisfactorily. The F.E T. is a low -noise, high gaindevice with many uses. and the dual gate F E.T. es of particular use for mixerand otter applications This book contains something of particular interest for every clam ofenthusiast - shortwave listener, radio amateur. experimenter or audiodevotee. A valuable addition to the library of all electronic enthusiasts.


Popular Electronic Projects BP49 Included in this book area collection of the most cc puiar types of projectswhich, we feel sure, will provide many designs to interest ail electronicsenthusiasts. All the circuits utilise modern, inexpensive - d freely availablecomponents The 27 projects selected cover a very wide range and are divided into tourteem areas. Radio Projects. Audio Projects, Household Protects and TestInstruments. An interesting addition to the library of both the beginner and moreadvanced constructor.


Electronic Music and Creative Tape Recording Electronic Music bathe new music of the 2Cth Century II playa a large panin "Pop" and "Rock" music and, in tact. there is scarcely a group withoutsome sort of electronic synthesiser or other effects generator.

It is possible with relatively simple apparatus to create completecompositions using electronic and sometimes non -electronic musicalsources. This book sets out toshow how Electronic Musiccen be madeathomewiththe simplest and most inexpensive equipment It describes how the soundsare generated and how these may be recorded to build up the finalComposition With the constructor in mind, several ideas are given tc enable a smellstudio to be built including a mixer and various sound effect units.

Circuits are included for VCO5, VCAs. Envelope Shapers, VCFs. Activeand Passive Mixers, Fuzz, Noise Generators. Metronomes and a 10 -NoteProgrammable Sequencer etc.

All the units shown have been successfully built and used by the authorand most of the projects can be built by the beginner. An unusual. fascinating and highly rewarding application of electronics

$4.50 plus 30c postage and handling. BP51

IC LM3900 Projects BP50 The purpose of this honk is to introduce the LM3900 to loe Technician.Experimenter and Hobbyist It provides the groundwork for both simple andmore advanced uses and is considerable more than just a collection of simple

'cuits or projects The LM3900 is dnlerent from conventional 'Op -Amps', it can be used formany of the usual applications as well as many new ones It isone of the mostversatile. inexpensive end freely evadable devices on the market today. The book is divided into sic basic sections. -

IntroductionAudio Applications

Simple Linear ApplicationsSemple Digital ApplicationsSignal Generator Circuits

Special Applications The LM3900 can do much more than is shown here - this is just anintroduction. Imagination is the only limitation with this useful device, butfirst the reader must know the basics and that is what this book is all about


1st Book of HI -Fl Loudspeaker Enclosures Contains 26 practical designs and ove- 40 drawings to enable theenthusiast 10 construct his own Hi -Fl Loudspeaker enclosures Includes the following types of enclosures -Corner Reflex, Base Reflex, Exponential Horn, Folded Horn, Tuned Pon,K ilpschorn Labyrinth, Tuned Column, Loaded Port, MultispeekerPanoramic etc. Also covers general construction hints and embellishing of cabinets aswell as a considerable amount of other useful information A must for the library of all audio enthuse/Ws No 205$2.95 plus 30c postage and handling.50 Simple L.E.D. Circuits BP42 The author of This book, Mr. R Soar, has compiled 50 interesting anduseful circuits and applications, covering many different branches ofelectronics, using one of the most Inexpensive and freely availablecomponents - the Light Emitting Diode (L.E D.) Also Includes circuits for the 707 Common Anode Display A useful book for the library of both beginner and more advancedenthusiast alike. Companion volume to book No. BP36 - 50 CIRCUITS USINGGERMANIUM, SILICON a ZENER DIODES by the same author.


Handbook of IC Audio Preamplifier 8Power Amplifier Construction BP35 Shows what audio IC's are. as well as how to use them. Includes practical constructional details of various IC and HybridIC/Transistor designs Of about 250mW to 100W output. This book is written by the very experienced and popular author Mr. F.G.Rayer who deals with the subject in four parts -Part I Understanding Audio IC'sPart II Preamplinbrs. Mixers and Tone ControlsPart Ill Power Amplifiers and SuppliesPart IV Hybrid Circuits An ideal book for both beginner and advanced enthusiast alike

$4.5u plus 30c postage and handling.

50 Projects Using Relays SCR's & Triaca Bp37 Relays, silicon controlled rectifiers (SCR's) end bi-directional triodesITRIACs) have a wide range of applications in electronics today. These mayextend over the whole field of motor Control: dimming and heat control,delayed. timing and light sensitive circuits and include warning devices.var10ue novelties. light modulators, priority indicators, excess voltagebreakers etc. In this book, the very experienced and popular author - Mr F.O. Payer -has given tried and practical working circuits which should present theminimum of difficulty for the enthusiast to construct. In most circuits there is a wide latitude in component values and types,allowing easy modification of circuitsor ready adaptionof themtwindividualneeds.le An ideal book for both beginner and advanced enthusiast alike

$4.50 plus 30c postage and handling.50 Projects Using IC CA3130 No.223 The CA 3130 Is currently one Of the more advanced operational amplifiersthatlsavailabletothehomeconstructor This means that itisoftencapabieola higher level of performance than many otherderlcesand that it often needsfewer ancillary components. In this book Mr. R.A. Penfold has designed and developed a number ofInteresting and useful projects which &redivided lntorive general categories.I Audio ProjectsII R F. ProjectsIII Test EquipmentIV Household nrojec:sV Miscellaneous Projects An ideal book for both the beginner and mole advanced enthusiast alike.


Electronic Projects for Beginners BP48 In this book the newcomer to electronics will find a wide range of easilymade projects, many complete with actual component and wiring layouts.Furthermore, a number of projects have been arranged so that they can beconstructed without any need for soldering and. thus, avoid the need for asoldering iron. This book which is written bythe veryexpenenced authorMr. F.O. Rayarisdivided into lour sections --

1. "No Soldering" Protects2 Miscellaneous Devices3 Radio and Audio Frequency4 Power Supplies

An absolute 'must' for all beginners in electronics.

$4.95 plus 30c postage and handling.50 CMOS IC Projects No.224 CMOS IC sere probably the most versatilerangeofdigrtaldevicesfor useby the amateur enthusiast They are suitable for an extraordinarily widerange of applications and are now also some of the most inexpensive andeasily available types of I.C. In this book Mr. R Penfold has designed and developed a number ofinteresting and useful projects which are divided into lour generalcategoriesI MullivibratorsII Amplifiers and OscillatorsIll Trigger DevicesIV Special Devices An Ideal book for both the beginner and more advanced enthusiasts alike.

$3.95 plus 30c postage and handling.Electronic Calculator Users Handbook BP33 An invaluable book for all calculator users whatever their age oroccupation, or whether they have the simplest or most sophisticated ofcalculators Presents formulae, data, methods of calculation, conversion factors etc.with the calculator user especially in mind, Often illustrated with simpleexamplesIncludes'.

The way to calculate, using only a simple four (unction calculatorTrigonometric functions fain, cos, tan)Hyperbolic functions (sine, cosh, tare)Logarithms, square roots and powers. A comprehensive saloon of conversion factors covering such commonconversions as length, area, volume and weight eta through to morespecialised conversions such as viscosity. illumination, and cargo shippingmeasures etc Formulae and data for VAT, discounts and mark up, currency conversion,interest, solutions of equations, binary and octal numbers. areas andvolumes, statistics and mathematics etc.


60Please order by number using the handy order card in this issue.

FEEDBACIn your Dec. 78 issue of ETI CanadaMagazine on page 66 "Tech Tips"there is a project called BCD ToneGenerator. I would like to know ifthere is a misprint on the "note; IC1- 2are 74141" or is this the actual No. ofthe chip. If this No. is actually true canyou please tell me where this chip canbe purchased. Preferably a location inmy area.

Tony AntillonElkhorn, WI 53121

The 74141 BCD to decimal decoder/NIXIE driver with open collectoroutputs. Cost is in the range of $2.00and a random survey of cataloguesindicates availability is good.As far as dealers in Wisconsin are

concerned, I'm afraid we can't helpyou (being Canadian). Check theads in this issue if you feel up to buyingacross the border.

I bought a TI58 calculator some timeago, and although I got a very goodinstrction book with it it still seemshard to program and also to find usesfor the programs.Your Softspot Department has had

some interesting problems. But thismonth's hasn't any. Please continuethe feature, I am sure others like ittoo.

John SavinkoffTahsis, B.C.

Gosh John, I don't know how totell you this but we've decided todrop Softspot. Among other thingsour studies indicate that interest wasn'tas high as we had hoped, and thiscombined with severe space restrictionshas forced us to make this decision(when was the last time you saw ETIData Sheets ?). We will be sendingcontributors back with suitable (wehope) apologies and thanks.

I've constructed a small light chaserkit which has a 74154 demultiplexerwhich drives 16 LED's in sequence.Can I make it trigger a 5 Amp TRIACgate by using several 75492 hex digitdrivers directly, or would I have to useopto -isolators to protect thedemultiplexer?

( ,,,

--Ant ,r-4,:

..- Tr,..1...35 -G., 2

Fig. 1

Would this idea work also to turna household 7 segment digital clockinto a giant size clock such as seenat service centers along highways?

Brent IlanSmiths Falls, Ont.

Normally we don't do technicalqueries not related to our projects, butit seems that the art of firing triacs is Fig.2

largely unknown. In your case you candrive the triac directly from the outputof the driver, as shown in Fig. 1. A valueof 100R is recommended for R 1.If you use this circuit be sure to isolateit electrically from everything in sight.

With this in mind, we recommend

MOC 3010

AC

RCA725005or equiv.

RCA725008or equiv.

some form of opto isolation device,such as Motorolas MOC 3010 or MOC3030 (Fig.2).

... more than you've heard of GIKTRoNIf you've heard a lead guitar lately, ringing outa string of clear, crisp notes-or a concertorgan thundering a thousand voices, you mayhave been hearing Oaktron loudspeakers.

Oaktron has made speakers for some of theleading names in the musical instrumentield-and the Hi -Fi field. And any field

where clear sound is important.

Over the past 25 years, you may have heardmore Oaktron speakers than any other brand.You've heard Oaktron in studios, theaters,. iscos, and homes of the Hi -Fi pros.From steel mill to ballet stage, you've heard aktron. And you've liked what you've heard.

Oaktron's M15Y2Musical speaker.300 Wattsof peak power.

Ask for Oaktron's speakercatalogue by circling theReader Service Card numberor by writingto:

omnitronla ltd. "):!

2056 Trans Canada Highwayi Dorval, Quebec H9P 2N4

Tel: (514) 683-6993

Circle No. 6 on Reader Service Card.ETI CANADA-JANUARY 1980 61

ETI Special Book ServiceSam's Books from ETI

Please see page 64 for prices and ordering instructions.

New Selection!

LED CIRCUITS AND PROJECTSby Forrest M. Mims Ill. Describes all kinds of LED applications-from digital displays and logic testerprobes to communication systems and travel aids for the blind. Discusses LEO installation. operatinghints, LED detector circuits, multiple -color LEDs. diode laser theory and operation, and much more.Lots of photos, graphs. tables, and drawings. 176 pages; 51/2 x 8%; softbound. (ISBN:0-672.21006-1)© 1973No. 21006

UNDERSTANDING IC OPERATIONAL AMPLIFIERS (2nd Edition)by Roger Melon and Harry Garland. Explains how IC op amps work and how they can be used in manypractical circuits. Features the newest material on FET op amps. Also gives detailed information onbasic semiconductor electronics, integrated op -amp circuitry, practical design considerations incircuits using IC op amps, bias current. offset voltage, frequency compensation, and slew rate. 128pages. 51/2 x 81/2; softbound. (ISBN: 0-872-21511-X) © 1978No. 21511

ACTIVE -FILTER COOKBOOKby Don Lancaster. A practical, user -oriented treatment of active filters. Explains what active filters areand how they work, and gives detailed information on design, analysis, and synthesis techniques.Explores some interesting applications for active filters in brainwave research, electronic music,quadrature an, and psychedelic lighting. 240 pages; 51 x 81/2; softbound. (ISBN: 0-872-21168-8) (<1975

No.21188

WIND/SOLAR ENERGY for Radiocommunications and Low -PowerElectronic/Electric Applicationsby Edward M. Noll. This is a book for those with an eye towards the future. It discusses the use of wind -and solar energy as alternative sources of electricity. It covers energy -conversion principles, bat-teries. inverters. alternators, the electric auto, and practical windlsolar applications such as a 200 -watt wind generator and a solar -powered amateur radio station. 208 pages; 51/2 x 81/2; softbound(ISBN: 0-672-21305-2) © 1975No. 21305

AUDIO CYCLOPEDIA (2nd Edition)by Dr. Howard M. Tremaine. A complete audio reference library in itself and the most comprehensiveand authoritative work on audio available. Covers every aspect of the audio art-from the basicprinciples of sound to the latest in solid-state equipment. Complete coverage of acoustics, motionpicture equipment, recording, reproduction, test equipment, audio measurements, and much more.3650 entries and hundreds of illustrations and schematics. 1760 pages; 61/2 x 93; hardbound. (ISBN.0-672-20875-7) © 1969No. 20875

ABC'S OF INTEGRATED CIRCUITS (2nd Edition)by Rufus P. Turner Especially written lot readers with a knowledge of basic electronics, this bookapproaches the survey of the IC in a descriptive and practical manner. The new edition describes thelatest circuits with a minimum of theory and mathematics 96 pages; 51/2 x 81; softbound (ISBN:0-672-21462-8) © 1977No. 21462

BUILDING AND INSTALLING ELECTRONIC INTRUSION ALARMS(2nd Edition)by John E. Cunningham. Countermeasures to offset crime are suggested in this book written for thenovice who wants to install a security system in his home and the technician who wishes to enter thelucrative field of security electronics. Countermeasures outlined include electromechanical intrusionalarms, sensors and switches, closed-circuit television, proximity alarms. power supplies, telephoneattachments, and alarms for the protection of automobiles. 128 pages; 51/2 x 814: softbound. (ISBN.0-872-21465-2) © 1977No. 21465

Held Over!.TTL COOKBOOKby Donald Lancaster. A complete and detailed guide to transistor -transistor logic Explainswhat TTL is, how it works, and how to use it. Discusses practical applications, suchas a digital counterand display system, events counter, electronic stopwatch, digital voltmeter. anda digital tachometer.336 pages: 51/2 x 81/2; softbound. (ISBN: 0-672-21035.5) © 1974No. 21035

UNDERSTANDING CMOS INTEGRATED CIRCUITSby Roger Meten and Harry Garland. Takes a building-block

approach to the subject of complementarymetal -oxide semiconductors. Begins with basic digital ICs; then covers semiconductor physics,CMOS fabrication technology and design, and advanced CMOS applications. 144 pages; 5v2 x 81/2;softbound. (ISBN: 0-672-21129-7) © 1975No. 21129

DBUG: AN 8080 INTERPRETIVE DEBUGGERby Jonathan A. Titus and Christopher A. Titus. This text describes DOUG, a software debuggingpackage for 8080 -based microcomputers. It describes the operation of the program and how it can beapplied to program development and testing. Complete with documentated hexadecimal and octallistings. 112 pages; 51/2 x 8%; softbound (ISBN 0-672-21536-5) © 1977No. 21536

DESIGN OF PHASE -LOCKED LOOP CIRCUITS, WITH EXPERIMENTSby Howard M. Berlin. The design of the basic PLL circuits is described; detector, phase comparator,and voltage -controlled oscillator circuits are detailed. Contains many practical circuits using the560 -series devices and the CMOS 4046 chip. With over 15 experiments.

288 pages; 51/2 x 81/2;softbound. (ISBN: 0-672-21545-4) © 1978No. 21545

MODERN RECORDING TECHNIQUESby Robert E. Runstein. Provides the information necessary to prepare pop music recordings. Explainsthe equipment, controls, and techniques found in the modern recording studio and how to use themnot only properly but creatively to produce a desired result. Numerous photographs, diagrams, andcharts. 368 pages; 51/2 x 81; softbound. (ISBN. 0-672.21037-1) © 1974No. 21037

HOW TO READ SCHEMATIC DIAGRAMS (3rd Edition)by Donald E. Herrington. Explains the various types of electronic diagrams, shows the schematicsymbols for the various components in a circuit, and explains their operation. Tells how they areconnected into circuits and gives the symbols for these connections. Variations likely to beencountered in both symbols and designations are treated at length. Review questions at end of eachchapter. 192 pages, 51/2 x 81/2; softbound. (ISBN: 0-672-21127-0) © 1975No. 21127

AVIATION ELECTRONICS (3rd Edition)by Keith Bose. Using a practical approach, this third edition updates, describes, and shows rep-resentative types of electronic equipment that is vital In today's aircraft. This informative handbookhas been written as a guide for aircraft owners, pilots, technicians, engineers, and anyone else whomight require a knowledge of aviation electronic equipment. It is liberally illustrated with photographs.schematics, and drawings. 300 pages; 51 x 8W; softbound. (ISBN: 0-672-21440-7) © 1977No. 21440

SOLAR CELLS AND PHOTOCELLSby Rufus P. Turner. An explanation of photocells and solar cells, and a selected collection of practicalapplications, such as a light -beam communicator, light -powered tone telegraph, and light -actuatedremote control. Addressed primarily to experimenters. technicians, and science fair entrants; as-sumes that the reader is already familiar with general electronics. 96 pages; 5'h x 8rh; softbound.(ISBN: 0.672-21175-0) © 1975No. 21175

30 IC PROJECTSby Herbert Friedman. Complete instructions, parts lists, and schematic diagrams for 30 differentintegrated -circuit projects, most of which can be built in a few hours and at low cost. The projectsinclude a walkie-talkie power pack, budget -priced tape -head preamplifier, 4 -channel microphonemixer, timed auto burglar alarm, light meter, stereo balancer, and portable intercom. 80 pages: 51/2 x81/2: softbound (ISBN: 0-672-21145-9)C) 1975No. 21145

IC TIMER COOKBOOKby Walter Jung. Provides an excellent introduction to the field of IC timers by presenting a collection ofvarious Circuit "recipes" useful in applying the devices. Arranged in three parts, the first part givesbasic and generalized information. Part II, the applications section, is the "meat" of the book andincludes over 100 different circuits for a wide range of uses. Part III contains reproductions ofmanufacturers data sheets. second -source manufacturers, and more. This book is a valuable refer-ence for the hobbyist, the technical or engineering student, or professional. 288 pages: 51/2 o 8W;softbound. (ISBN: 0-672-21416-4) © 1977No. 21416

ETI Special Book Service (CONTINUED)

CMOS COOKBOOKby Don Lancaster. Tells all you need to know to understand and profitably use this inexpensive andgenuinely fun to work with digital logic family. First an explanation o1 what CMOS is, how it works, andhow to power it, plus usage rules, state testing. breadboarding, interface, and Other basics is given.Then a minicatalog of over 100 devices: including pinouts and use descriptions is given. Subjectscovered include gate fundamentals, to -state logic, redundant logic design techniques, multivibrators,nonvolatile memory techniques, clocked Jk and D flip-flop. counter and register techniques, op amps,analog switches, phase -locked loops and much more. A must for the student, hobbyist, teacher.technician, or engineer who wants to learn about CMOS. Filled with practical applications. 418 pages:51 x 81/2; softbound. (ISBN: 0-672-21398-2) ,c' 1977No. 21398

TV TYPEWRITER COOKBOOKby Don Lancaster. An in-depth coverage of N typewriters (IN's)-the only truly low -Cost microcompu-ter and small -systems display interface. Covers M terminology, principles of operation, M configura-tions, memories, system design, cursor and update circuitry and techniques, hard copy, colorgraphics, and keyboards and encoders. 256 pages; 51/2 x81/2; ; softbound (ISBN: 0-672-21313) © 1976No. 21313

555 TIMER APPLICATIONS SOURCEBOOK, WITH EXPERIMENTSby Howard M. Berlin. Deals with the many applications of the popular 555 timer "chip." Uses forvoltage regulation, control, sequencing are covered as well as the more usual timing and signalgenerating functions. With many useful circuits end 15 detailed experiments. 160 pages: 51/2 x 81/2;softbound. (ISBN' 0-672-21538-11 © t976No. 21538

Z-80 MICROCOMPUTER HANDBOOKby William Barden, Jr. The Zi log Model Z-80 represents a microprocessor that is extremely sophisti-cated and attractive to many computer users. This handbook will provide the current user and theprospective user with essential information on the technology of the 2-80. Organized into threesections, the first section concentrates on hardware; the second on software; and the third onmicrocomputers built around the Z-80. 304 pages: 51/2 x 81 ; softbound. (ISBN' 0-672-21500-4)1978

No. 21500

THE CHEAP VIDEO COOKBOOKby Don Lancaster. A complete guide to super low cost alphanumeric and graphic microprocessor -based video displays. Contains complete construction details on a seven IC circuit that dramaticallyslashes the cost of getting words, op -code, and graphics out of a microcomputer and into a televisionset. Includes thoroughly documented and debugged software. Enables you to produce virtually anyalphanumeric format, including scrolling 24 lines by 80 characters, and virtually any graphics format.including high resolution 256 x 256 mode and four-color graphics. Also contains complete details ontransparency techniques that let you compute and display at the same time with high throughput. 288pages; 51/2 x 81/2; softbound. (ISBN: 0-672-21524-1) ©, 1978No. 21524

THE 8080A BUGBOOK5: MICROCOMPUTER INTERFACING ANDPROGRAMMINGby Peter H. Rosy, David G. Larsen, and Jonathan A. Titus. The principles, concepts, and applicationsof an 8 -bit microcomputer based on the 8080 microprocessor IC chip. The emphasis is on thecomputer as a controller. Covers the four fundamental tasks of computer interfacing: (1) generation ofdevice select pulses; (2) latching of output data: (3) acquisition of input data; (4) servicing of interruptsignals. Intended to help develop the skills needed to use an 8080 -based breadboard microcomputersystem. BUGBOOKA is a registered trademark of E 8 L Instruments. Inc.. Derby, Connecticut 06418.416 pages; 51/2 x 81/2: softbound. (ISBN: 0-672-21447-4) ie; 1977No. 21447

USING THE 6800 MICROPROCESSORby Elmer Poe. No special background in digital electronics is necessary to enjoy the 6800 micro-processor. This book will acquaint the reader with the hardware and software of the 6800 "fun"machine. It will guide the reader through the conception, configuration, writing, and running of avariety of programs that demonstrate the practical use of a 6800 system. Features fifteeninformation -packed chapters with an appendix which includes a detachable programmer'scard. 176pages: 51/2 x 81/2; softbound. (ISBN: 0-672-21512-8) 'cl 1978No. 21512

Please see page 64 for prices and ordering instructions.

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INITIATION A L'ÉLECTRICITEET A L'ÉLECTRONIOUE F91

200 Manipulations simplesd'éléctricité et d'éléctronique

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POUR S'INITIER A L'ÉLECTRONIOUE F12L'auteur a daunt dens col ouvrage Joule une ºene de montages simples qui one arerealises. essay,! el Wantonnes en raison de I mlerett qu as pouvelenl on nr susamateurs. Cae montages prllsanlenl cependent la paniculante d stye *quipes descomposents tras courants, montes sur do pl*quebes spectates a bandas conduc-Inces toutes pertoraes appele. piaquenes le BOARD - Grace ace, supports demontage. les realisations peuvent 5 !Mettler comete de veritables cue decOnstruc-Iron. tele tit ''intention de I'sateur car dens cat ouvrage it s'agn d' applications etnon datude reberbetive SOMMAIRE Jeu de reflexes. disposal' delumrerepsyghe-delrque pour autoradio. Gadget automobile Orgue monodique Recepleur d'etec.Irrcde statque. Flash a celluie LDR Indicateur de niveau BF Metronome audio-vstin Oreille elleclronique Detecteur de elute Disposiln attire-poissons. etc

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D'AUTRES MONTAGES SIMPLES...D'INITIATION F84

Un °uvrage Ours soreºse a bous un support de montage revolutionnarredes realisations enberemenl detainees Iplana de cablege. pnolograpnres.Isles des composanls) Des listes O caresses pour I'achei des compusank

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R. DUGEHAULT C,,,ler.non Sottor,iqua conrempvrei,e

L'AMPLIFICATEUR OPERATIONNEL F7COUPS PRATIOUE D'UTILISATIONPresenter I amplil,caleur operatronnel. en decree la structure interne defino sescaractenstiques entailer soncomportemenl dons lea six chemes fondamenuussalon lesquels it pent erre utilise. tel eat le but de cal ouvrageSon application premiere. 9 [ere des calculateurs analogiques. else et eel encore.la res olunon d operations mame ceros

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Alan DOUGLAS

PRODUCTION F75DE LA MUSIQUE ÉLECTRONIQUE

Le musque electronique paasronne actueilement les electronrnens. les mull-s. acoustic...s,les acoustic. airier clue tour les apecialu ..

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Un volume broche. formas 15 x 21. de 152 pages, couverlure couleu,

F. JUSTER

30 MONTAGES ELECTRONIQUES D'ALARMEUn ouvrage mieressera taus ueus our desuero se proteger contra elf Wk.

endres lesuaz et mes eau, c ese -a -dire lout re mondeEsTRAIr DU SOMMAIREAlarmes pour divers usages Ala Ines Optoelectroniques Alarm. de temperature.Suenes elerirdn,oues Alarmes a circuits Iogiques Alarmes a 'c,rcu,ls integresDetecieu, de lumen el oe gat

Jr' vnrume Crone 120 pages format 12 - le 5 Couverlure [Outeur,

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COMMENT CONSTRUIREBAFFLES ET ENCEINTES ACOUSTIQUES

canon,

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daunt les types les plus courants d encemtes eeper,nenles pardes irmes specialr-sees en se bornent prinapelemenl aua modeles tacilemenl reabsabtn oar un ama.lour SOMMAIRE Le Haut-Perleur e:ectroeynamque Fonctlonnemenl electriquedu Haul-Parleur Fonctlonnemenl acouslrque du Haut-Parleur Benles ou acrensplans Comets cros Encere res ecouslgces a ouve.tures Enceintes diversas En.eintes Bass -reflex Enceinles a papillon Comment Cuomo un Haul-Parleur

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LES JEUX DE LUMIERE

et effete Sonoras pour guitars. electrique

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un ouvrage de 128 pages Format 15 21. 122 scnernas al ,llusrrarlons, soucOuverrure quaarrchromie peilrculae

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INITIATION A LA MICROINFORMATIOUELE MICROPROCESSEUR F125

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tin volume b&Ocher de 136 pages, so figures. former 12 1..5. eau. couverlurepeliloWn

Prix et renseignements pour les commandes en page64.

Order Form Bon de commandeNAME/NOM:

A(D)DRESS(E):

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PROVINCE: CODE POSTAL:

DATE:QUANTITYQUANTITE NO. TITLE

TITRE21037 Modern Rec...15oz $13.9521127 How to Read...8oz $7.2521168 Active Filt...10oz $19.9521462 ABCs of ICs...5oz $5.2521465 Building and Inst...6oz $6.7521511 Understanding IC...6oz $6.7521536 D.BUG 8080...5oz $6.7521545 Design PLL...10oz $11.9520675 Audio Cyclopedia...32oz $52.9521305 Wind/Solar...9oz $10.5021440 Aviation Elec...10oz $11.9521129 Understand CMOS...7oz $6.7521006 LED Circuits...7oz $7.0021145 30 IC Proj...4oz $4.7521175 Solar Cells...1loz $5.50

21035 TTL Cookbook...13oz $12.7521416 IC Timer...l2oz $13.2521398 CMOS Cookbook... 16oz $13.9521538 The 555 Timer...7.5oz $7.9521524 Cheap Video...11oz $7.9521313 TV Typewriter...11oz $13.2521500 The Z80...12.5oz $11.9521447 8080A Bugbook...16oz $13.9521512 Using the 6800...8oz $9.25

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NEXT MONT1900fEB /NIII

Series 4000 Moving Coil Preamplifier.

Moving coil cartridges have excellenttransient response and relatively highsignal accuracy. Unfortunately theysuffer from very low output levels. TheSeries 4000 will boost those signalswithout adding any appreciable noise.

Egg Timer (how to make youreg9iwegs just right)

Most egg timer projects just sit thereand beep. Our egg timer offers twotime options as well as a battery savingfeature. Egg-zac. . .er. ..exactly whatyou should give Mom on her birthday.

Practical Guide to Triacs Part Ill

Zero crossing doesn't mean a triaccircuit isn't going anywhere, it's justgenerating less RF interference. Nextmonth Collyn Rivers explains how touse triacs with large loads.

Teletype Receiver.

A quick and easy to build way toget into radio teletype (provided youcan get a teletype).

The articles mentioned here are In an ad-vanced stage of preparation. Circumstancesmay dictate changes In the final contents.

Teachers' TopicsThis month we take a close look at an educational "lab" system,designed to teach logic and computer fundamentals by "hands-on"experiments. A very complete manual -textbook for students is partof the system.

WE ARE ALWAYS on the look -outfor products which would be parti-cularly useful in learning electronics,and so we were happy to hear about a"Computer Logic Lab" from TektronEquipment Corporation.

We should mention that Tektron islocated near Hamilton, Ontario, and isrun by Eugene Tekatch, who is activelyinvolved in various educationalendeavours One of his best knownefforts is probably the TEC 1802microprocessor kit, and associatedcourse offered by the IEEE.

THE LOGIC LAB COURSE

Back to the Logic Lab, - what'sit ,ntended to help teach? Well, logicof course! But to put it in more detail,a look at the very complete 150 pagemanual is in order. In fact, this is notjust a manual, but a complete coursetext for students. The subject areascovered include: basic boolean algebra,binary number system, memory de-vices, shift registers, serial and parallelcounters, serial and parallel addition andsubtraction, binary multiplication,binary codes and conversion and systemsynchronization.

Each of the above subject areas is

covered as one or two chapters in thetext, wherein a description of thearea is given, followed by a series ofexperiments with various hook-upsfor the Logic Lab apparatus, and ques-tions on its operation to be answered.

THE EQUIPMENT

Shown in Figure 1 is the frontpanel of the Model 100 "Main Unit",which comprises a "Main Logic Mod-ule" and an "Auxilary Logic Mod-ule", containg the logic gates withinputs and outputs brought out to frontpanel connectors, "Switching and Dis-play Module" which provides switchesfor inputs and LEDs for output indica-tors, and of course, finally a Power

Supply for the whole lot. Intercon-nection is via patch -cords. Using thisarray of logic, the student can attackall the subjects in the text.

We found the text to be quite clearand concise, in fact an impressive pieceof work. Thankfully, it stayed clearto a great extent of the actual elec-tronics of the situation. That is, verylittle mention was made of voltages,

Fig. 1. Here's the mainunit, showing logic"console" switches,indicators, powersupply etc. Thisdiagram providedin the text can bephotocopied andused for drawingpatching arrangements.

transistors, resistors and so on. Thestudent is treated to a "higher level"discussion, that is at the logic symbollevel. This is quite a sensible approach,since the knowledge gained from thisset-up (which happens to be TTL) isgenerally applicable to all logic -infor-mation processing and does not confusethe issues by dealing with the peculiar-ities of any one logic family.. . D--

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Teachers' Topics

ACCESSORIES

To augment the Model 100 justdescribed, there is available a Bread-board Module, which allows you toeasily interface your Logic Lab to what-ever integrated circuits you wish. Thismight be useful for experimenting withmany of the special and complex func-tion ICs available.

There is also a patch -cord -to -edge -connection adapter module.

FROM THERE?

As can be seen by looking at thelist of subjects covered in the "Basic"set, it leads the user in the direction ofreal computer logic functions. To gofurther in that direction you progressto the "Central Processing Unit" whichis shown in Figure 2. This unit con-tains all the registers, counters, latchesand data routing logic that a micropro-cessor has, plus an adder to representarithmetic logic, and a 256 byte mem-ory.

In short, it contains all the constitu-ents to put together the equivalent ofa (somewhat unsophisticated) micro-processor, with all inputs and outputs,usually hidden inside an mpu, nowavailable to view.

While we have not seen the man-ual for this unit, we understand it is

written in the same excellent form asthe basic manual. It leads the studentthrough combining the circuits invarious ways to the final experiment ofconnecting the whole lot together intoan 8 bit parallel bus computer.

AND THEN?

Once at this stage, it would be diff-icult to move on up with this formatof experimental unit: just too manywires! And so we find we have reallyarrived at the point where the studentcan progress to the aforementionedTEC 1802, and the IEEE course men-tioned, dealing in great detail withmicroprocessor matters.

WHO'S IT FOR?

This series of lab style learningequipment is suitable for high schools,colleges and universities. Thus far,Tekatch notes that very few highschools have bought his systems, al-though many have found their ways in-to colleges and universities. He says itappears to be a case of funding. Weagree with him that it's a pity thatthe money, representing only a small

Fig. 2. The next step up the ladder to complete knowledge of computer operation,is this "central processing unit". It may ultimately be used to make a demonstrationcomputer.

fractiort of a teacher's salary, is notthere to enable students to get a gripon the technology we must live with.And surely such educational aids asthis logic lab must be worth theirproportionate cost in communi-cations -teaching power.

One wonders how long auto -shopstudents would maintain interest ifall that their teachers could afford todo was come in each day and just showthem pictures of '65 Valiants.INFORMATION

For full details write to: EugeneTekatch, Tektron Equipment Corpor-ation, 263 Barton St. E., StoneyCreek, Ontario L8E 2K4. Phone(416) 662-7820. To get an idea ofthe depth of the overall course, send$6.50 for the new (still at the printersas we write this) expanded textbook forthe main logic lab plus central processorunit.

CONTRIBUTE!Teachers and students are encour-

aged to send material for this column onany area involved with the teaching orlearning about electronics. We wel-come news about what your school,board, or association is doing. (If youwish to contribute news of upcomingevents, please note that we need toreceive notice,at least 45 days beforethe first of the issue month.) Send yourletters to:

TEACHERS'S TOPICS, ElectronicsToday Magazine, Unit 6, 25 OverleaBlvd., Toronto Ont., M4H 181.

Mr. Richard Torrents is a Wellexperienced electronics developrneengineer and has designed, developbuilt and tested the many useful andinteresting circuits included in this

Some of the circuits are completelynew and, to the best knowledge of theauthor, unlike anything previouslypublished wail° others may bearsimilarity to more familiar designs.

The projects themselves > can be splitdown into simpler building blocks,which are shown separatec by boxes inthe circuits for ease of deecription, andalso to enable any reader who wishes tocombine fazes tram different projects

s own.

Most o t e c rcuits are veryeconomical on the use of componentsand In many cases the semiconductorsemployed are non -critical, commonlyavailable and Inexpensive types.

Babani No. 221.$4.50 plus 30c post and handling.Please use handy card to order.

If we publish your letter or ideas wewill award your department or schoollibrary a free subscription to ETI.

1191$~' 'v"`.+i'r.>:.`Lt:i::%rJi,.r.'iti9iJ:<!sYj':~vS?

:; 1Q¿:i:ii4W"IY l::!?:f:i:~i6%:.,:L4:::':,+::yh,::4i:'bSLii:':'%. ifG4ifG:v.i ^5Cgt


LISTEN TO AFRICATHE MAP OF AFRICA has changed

considerably since my high schooldays when there were forty countrieson that continent. Of those forty onlyseventeen still have the same name asthey had 32 years ago and there aremany more countries. Listed this monthare fifty-five African nations withshortwave services. Some of these willbe very difficult to hear and will requiremuch patience on the part of thelistener. Countries are referred to on amap by the number appearing by thecountry's name in the text. Good Luck!

So there you have a little geographywith your Shortwave News.Good luckin your search for the African stations.

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1. Algeria - The short wave broadcasts from Algeria have been quiteerratic. Some frequencies reported in recent months are 7195, 9509,11633, 11810 and 15160 in French; 9685 and 9705 in Arabic. English hasbeen heard al 1145 and at 2000-2030 on 9810. Radiodiffusion-Television Algerienne, Radio Algiers, 21 Blvd des Martyrs, Algiers.2. Angola - Sometimes heard here, their schedule shows weekdaysfrom 0630-0800, 1100.1200 on 7245, 9535, 11955 and from 1430-2200on 7245 and 9535. Sunday from 1600-1800 on 7245 and 9535 - Thisincludes English at 1130-1200, French 1100-1130 and Spanish 2030-2130. Various Liberation organizations operate in English andvernaculars between 1630 and 1800. Other times Portuguese is used.Also try 3375 at 0400 and 7215 at 0700. Radio Nacional, C.P. 1329,Luanda.3. Ascension Island - The BBC operate their Atlantic relay from thisisland. It is usually heard vary well here in Central Canada. Many timesand frequencies are used for this service. Some to try are 15400 from1430.1745, 9580 from 2300-0330. 11820 from 1800-2030 and 15260from 2000-0230 BBC. Bush House, P.O. Box 76, London WC 28 4PH,England.4 Benin- They sign on at 0415 daily on 4870 mostly in French Englishhas been reported at 1940 but isn't too likely to be heard here at thattime and frequency. La Voix du Revolution Populaire. B.P. 366,Contonou.5. Botswana - Try 3356 between 0400 and 0630 or 5965 between 0530and 1400. Some transmissions include relays of English news from theBBC. Radio Botswana, P.O. Box 52,Gaberone.6. Burundi - The languages used on this station are French, Swahiliand Kirundi. You might try 3300 (or 3330) Irom 0330-0600 or6140from1000 to fade out. La Voz de le Revolution, B. P. 190. Bujumbura.7. Cameroon - Often heard quite well here on 4850, 9745 and 17750between 0430 and 0730 and 1000-2200. English and French are used.Radio Yaounde. B.P. 281, Yaounde.8. Canary Islands - Radio Nacional de Espana operates from theCanary Islands in Spanish on 6090 from 1730-1930 and on 11880 (or11815) from 1730-1930 (Sunday 2045-2300). Some niceSpanish musicis sometimes heard here. Radio National de Espana. Centro Emisor deAtlantico. via RNE. General Vague 1. Madrid 20, Spain.

9. Cape Verde - Two frequencies are listed here, 3930 and 7155although I've never heard them. Their schedule shows Monday toFriday at 0700-0830. 1500-1630, 2030-2400. Saturday 1600-2400 andSunday 1100-1400 and 1600-2400. Radio Voz do Sao Vicente. C.P. 29,Mindelo, Sao Vicente Island.10, Central African Empire - Reported by North American listenersnow and then, they are on the air from 0430-0700 and 1830-2300 on5038, and from 0730-1830 on 7220. La Voix de I'Empire Centrafricaine.B.P. 940, Bangui.11. Chad - The schedulefor Chad shows 0430-0630and 1800-2200on4904.5. and from 1045-1800 on 7120. English language lessons arelisted of 1850 on Monday to Friday. Radiodiffueion NationalTchadienne, B.P. 892. Njama.

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12. Comoro State -A tough one. They are on the air from 0300-0400and 1800-2000 on 3331 ancHrom 0300-1500 on 7260. Both stations arefour kilowatts so you will need a lot of luck for this country. RadioComoros International, B.P. 250, Moroni.13. Congo -This one isheard frequently. English used tube used but itapparently has been dropped from their transmissions. They are nowIn French and some African languages. Their latest schedule shows0400-0700 on 3284; 07001100 on 7105 and 9715; 1100-1700 on 7105,9715, 15190; and from 1700 to 2300on 3264 and 15190. RadiodifussionTelevision Congolaise, (La Voladu Revolution Congolaise), B.P.2241,Brazzaville14. Egypt - Radio Cairo is a fairly easy African station to hear. Theyhave English directed tV North America from 0200-0330 on 9475 and12050. They also broadcast throughout the day to other areas inEnglish and 31 other languages. Radio Cairo, Engineering Dept., P.O.Box 1186 Cairo.15. Equatorial Guinea - Two low power stations operate from hereinSpanish and vernaculars on 8250 from 0500-2300 and on 4926 from0430-2130 (Sunday 0700-2130). Radio Malabo, Apto. 125, Malabo,Fernando Poo. Radio Equatorial, Apto. 57, Bata, Rio Muni.16. Ethiopia - The voice of Revolutionary Ethiopia took over thereligious station "Radio Voice of the Gospel" a few years ago after therevolution there. English is listed from 1800-1700 on 7165 and 9815.Although not listed they have been reportedly heard on 9815 between1800 and 1845.17. Gabon -A station Identifying itself as"Africa Number One' begantest transmissions from Gabon last fall. They were trying a number ofdifferent frequencies and as I write this report. I don't know which theyfinally settled on. They were awaiting listeners reception reports inorder to determine which frequencies proved best for reception. Somefrequencies used were 11755, 11835, 11910, 11945, 15125, 15200,15270,15325,15415,17820,17835, 17845, and 21635between 0400and2100. They are using four 500 kilowatt transmitters so they should beheard quite easily. Africa Number 1,Mallbox No. 1, Libreville, Gabon.18. Ghana - Radio Ghana's external service operates on 6130 withEnglish from 0700 to 0900; 1600-1700 and from 2000-2300. Thedomestic service from Accra has been reported on 4915 in English et0600. Radio Ghana, P.O. Box 1633, Accra.19. Guinea-Bissau -This is occasionally reported by North Americanlisteners. You might try 5041 between 0600-2400. This is a 10 kilowattstation. Radiodifusora Nacional, C.P. 191, Bissau.20. Guinea (Rep) - Radio Nationale isoften reported on 15310around1800. Their schedule shows French or vernaculars on 4910 and 8155from 1230-0830 (these are both 18 kilowatt transmitters); 7125 from1600-0830: 9650 and 15310 from 1230-0830 (100 kilowatts for thesethree frequencies. They have occaselonal broadcasts in English.Radiodilusion Nationale, La Voix du Revolution, B.P. 617, Conakry.21. Ivory Coast - This one is quite well heard here in French aroundsign on time of 0600 on 4940 and 7215. 11920 is heard around 2100hours. All three frequencies are listed from 0600-2400. English isscheduled from 1845-2000. Radio Abidjan, B.P. 2261, Abidjan.

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22. Jlbutl - The only shortwave frequency used by Jibuti is 4780. Thelanguages used are Somali and Afar from 0300-0600 (Fri. 0500-0900),0900-1300 and 1600-1900. This one is difficult partly because of thelanguage but mainly due to the low transmitter power of only 4 kilo-watts. Good luck! Radio of the Republic of Jibuti, B.P. 97, Djibouti.

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23. Konya -The Voice of Kenya usesa number of frequencies, some of100 kilowatts and are often reported as being heard in North America.Their General Service in English is scheduled on 4804 at 0300 (Sun.0330) to 0620; 1300 (Sat 8 Sun 1330) to 2010 (Sat. 2110) and on 7125from 0900 to 1100 (Sat. 8 Sun.0630-1320).4934 has also been reportedrecently with English on Sundays starling at 0400. African languagesare used on this frequency on other days. Voice of Kenya. Box 30456.Nairobi.24. Lesotho -A ten kilowatt station broadcasts on 4800 from 0400 to2100 in Sesotho and English. They expect to have two 50 kilowatttransmitters in service soon. Radio Lesotho, P.O. Box 552, Maseru.25. Liberia - The religious station ELWA in Monrovia can be heardhere quite easily. Their English schedule shows 0700-0800 (Sat.) and0700 to 0730 (Sun.) on 11830:1345-1630(Sun.)end 2015-2130dailyon11860.

The Liberian Broadcasting Corporation operates station ELBC on6090 between 0528-1000 and 1200-1830. They expect to increasepower from 10 to 50 kilowatts soon and also to add 3255 kilohertz.

The Voice of America also operates a well -heard relay station inMonrovia on many frequencies. Try 6035 around 0430: 7280 between0330 and 0700; 9670 about 0500; 12010 at 2200; 15235 at 0100, 15445about 2000 and 17860 from 0300. ELWA, Box 192. Monrovia.Liberian Broadcasting Corporation (ELBC), Box 594, Monrovia.Voice of America, Public Information Office, Washington,DC 20547,

USA.

26. Ubya - Radio Mediterranean from Cyclops. Malta carriesprogramming from Libya at 0700-0800 on 5960 and 7135 and 1900-2000 on 5960.They also have English on Saturday and Sundayon 5960from 1000-1045. People's Revolutionary Broadcasting Corp.,Planning and Training Department, Ministry of Information, P.O. Box333, Tripoli.27. Madageacar - Radio Madagasikera broadcasts In Malagasy andFrench on 2495 from 0300-0500; on 3285 from 0300-0600: on 5010 from0300-1630. 6135 from 0300-1600; 7155 from 0600-1300 and on 9690from 0600-1300. 3285 is a 100 kilowatt transmitter. The others are lowpowered.

A much easier station to listen to from Madagascar is the RadioNederland's relay there. Their English transmissions from this Africanisland are: 21480 and 17855 from 1430-1525; 11730 and 6020 from1830-1920: 15270 and 11730 from 2030-2130.

RTV Malagasy, B.P. 442, Tananarive.Radio Nederland, P.O. Box 222, Hilversum, Holland.

28. Malawi - The International Service is heard between 1600 and1800 in English and Chichewa on 3380. 5995 and 7130. The samefrequencies are also used for the home service in English andChichewa languages between 0300 and 2200 (Not all three are onat thesame time). Malawi Broadcasting Corporation. P.O. Box 30113.Chicheri, Blantyre.29 Mall - 4825 and 5995 are scheduled between 0600 and 0800 onweekdays; 7110. 7275, 9635 and 11960 are listed from 1200-1500 (Fri.,Sat. 8 Sun. 0800-1800. Thurs. 1200-1800) and 4825 and 5995 from1800-2400. Most of the programming is in French with.English newslisted at 1830 on Sunday. Radiodiffusion du Mali, B.P. 171. Bamako.30. Mauritania- Three 100 kilowatt transmittershereoperate on 4845from 0600-0900 and 1800-2310 (Fri., Sat., Sun. to 2400); on 6120 from0600-0900, 1200-1600, 1800-2310 (Sun. 0600-2400) and on 9610 from0900-1200 and 1600-1800 (Sun 0700.2000). English is broadcast from1900 to 1930 with French. Spanish, Arabic and vernaculars at othertimes. Probably the most likely is 4845 from 0600-0900 i1 you're up atthat time. Mauritanian Radio, B.P. 200, Nouakcott.31 Mauritius- Certainly not a powerhouse but occasionally heard inNorth America from their ten kilowatt transmitters on 4850 from 130°-1830 (Sat to 1900) and on 9710 from 0200-1300. English and French arelisted from 0300-1030 (Sun., Tues. Thurs, to 0930) and from 1430-1830(Sat. to 1900). Indian languages and Chinese are used at other times.Mauritius Broadcasting Corporation, Broadcasting House, ForestSide.32. Morocco - Arabic from Tangier may sometimes be heard fromthese 50 or 100 kilowatt transmitters: 15360 from 1000-1700: 15335from 1000-1900; 21735 from 1100-0100; 9540 from 1700-2100; 15155from 1900-0100; and on 6095 from 2100-2400.

The Voice of America also hasa relay in Morocco on about twodozenfrequencies. Some are 7220 at 0430; 7295 at 0615; 11760 about 2000;15155 at 2300; 15245 at 0430, and 21735 around 0000.

Radiodiffusion Television Marocaine, Royaume du Maroc,Ministere de I'Informatiion, 1 Rue al Brihl, Rabat.

Voice of America, Public Information Office. Washington, DC.20547, USA33. Mozamblque - Most of the programming here is in Portugueseand vernaculars. Try the following: 7240 and 9610 from 0255-2210:3210 from 0255-0515; 4885 from 0255-0545; and on 11820 from 0500-2210. Radio Mozambique. C.P. 594, Maputo.34 Niger - This is another of the countries which is only heardoccasionally here. You might try 3260 on weekdays between 0530 and0630. Don't get your hopea upl Radio Niger, (La Voix du Sahel), B.P.361, Niamey.35 Nigeria - The Voice of Nigeria is easily heard here in NorthAmerica. The best time is from 0455-0600 on 7255 and from 0455-0630on 15120 There area number of low powered regional stations whichmany Oxers like to hunt. A 50 kilowatt station in Lagos is often reportedon 4990 which is on the air from 0430-1000 and 1700-2305. Voice ofNigeria. External Service, P.M.B. 12504, Broadcasting House, Lagos.36. Rwanda- Radio Rwanda operates with 5kilowattson 3330 and 50kilowatts on 6055 in French, Swahili end Kinyarwanda (I wonder howmany of our readers understand this language) at 0300-0600 onweekdays: 0900 to 1200 (Sat, Sun. to 1330), 1330-2100 and on Sundayfrom 0300-2100.

The Deutsche Welle relay at Kigali is heard frequently with Germanat 1800-2150on 6160,9735:2200-0150 on 9700 and 15410. English from0430-0515 on 7225 and 9565:0930-1030 on 17800 and 21540: 1045 to1115 on 11785and 15410:1200-1245 on 15410and 17765:1715-1745 on9735 and 11965. French at 0515-0545 on 7225 and 9565:1315-1400 on15410 and 17765: and 1515-1615 on 9735and 11965. Radiodiffusion dela Republique Rwandaise, B.P. 83, Kigali.37 Sao Tome & Pincipe - I don't remember ever seeing this stationreported by listeners in North America. They are listed on 4807.5 withten kilowatts from 0530-2300 in Portuguese. Give it a try. RadioNacional do Sao Tome, C.P. 44, Hernique, Sao Tome e Principe38. Senegal - You might hear some French or vernaculars fromSenegal between 0600 end 0800 on 4890. Some other times andfrequencies are 3338 from 0600-0800; 4952 from 0400-0100; 7170from1000-1800; 7210 from 0600-1800: and 11895 from 1000-2400.Radiodiffusion du Senegal, B.P. 1765, Dakar.39. Seychelles - The FEBA missionary station on this island in theIndian Ocean is often heard here. English is listed on 11805from 0400-0445; 15160 from 0700-0800; 15325 and 11855 from 1530-1630. Anumber of other languages are oleo used. Far East BroadcastingAssociation (FEBA). P O. Box 234. Victoria.

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40 Siena Leone - Sign onlrom this station isat0600wilh English andvernaculars. The frequencies used are 3316 and 5980 between 0600and 1030. Sierre Leone Broadcasting Service, New England,Freetown.41. Somalia - Radio Mogadishu is often reported with their 50kilowatts of power. Most programs are in Somali and vernaculars withsome English and Arabic. The frequencies in use are- 6095 from 0300-0500 (Fri. 0400-0600), 0900 (Fri. 1000)-2100: and 9585 from 0700-1930Around 1700 GMT has recently been reported on both frequencies.Radio Mogadishu, Ministry of Information and National Guidance,Private Bag. Mogadishu.42. South Africa - This is, nodoubtthe most listened to of the Africanstations because of their high powertransmissions directed especiallyto North America. English to North America is on the air from 0200-0250 on 15220.11900, 9610and 9585. Other English programs are airedat 0300-0426 on 5980. 7270, 9581 11900 and 15220. 0600-0658 on17780, 21535 and 25790;1100-1156 on 15220.21535and 25790.1300ío1500 on 15220, 17780 (Sun). 21535 and 25790; 1500-1550 on 15220,21535 and 25790; 2100-2150 on 15151 17780 and 21535. They alsobroadcast in other languages. Radio RSA. P.O. Box 4559,Johannesburg 2000.43. South Weal Africa/Namibia - The South West AfricaBroadcasting Corporation has taken over from the South AfricanBroadcasting Corporation and expect to broadcast from this area bythe end of 1980.44. Sudan - This is another country heard infrequently here. Sometimes and frequencies to try are: 5039 and 8150 from 1600-2200 inArabic or Somali and occasionally English, although the Englishportion is et 1630 which is too early to propagate to North America.Sudan Broadcasting Service (Radio Omdurman), P.O. Box 572, r

Omdurman45 Swaziland - Trans World Radio, a religious broadcaster. hasEnglish from Manzini at 0430-0630 on 5055 and 9640; 0645-0835 on9640 and 11910: 1200-1415 on9640:1530-1545on11840;1630-18000n15410; and 1800-1920 on 7260. Trans World Radio. P.O. Box 64Manzini46 Tanzania - The latest schedule I have for Radio Tanzania hasEnglish from 0300-0430 on 5050; 0430-0530 on 15435; 0930-1030 (Sat.8 Sun. to 153 on 9750; 1600-1945 on 4785 815435. Theyaiso haveanoutlet from Zanzibar on 3339 reportedly on air in Swahili from 0300-0500,0900-1100 and 1430-2000. Radio Tanzania. P.O. Box 1178, DaresSalaam

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'7. Togo- French and vernaculars are heard from hereon 5047 fromb530-0800 and 1700-2400. 7265 from 0800-1700. Radiodiffusion duTogo, B.P 434. Lome.48 Tristan da Cunha -A nice catch if you can get it. and you canget itif you try .. and try ... and try. 3290 with 40 watts of power is scheduledon Sunday. Wednesday and Friday from 1900-2205. Tristan Radio,Tristan da Cunha, c/o Capetown. Republic of South Africa.49. Tunisia - Three 50 kilowatt transmitters are in use here - 7225.11970. and 15225 from 0430-2330 in Arabic. Some French may also beheard. Radiodiffusion Television Tunislenne. 71 Avenue de la Liberte,Tunis.50. Uganda - The external service Is beamed to North America on15325 from 0305-0400 in English and from 0400-0430 in French. Alsotry 15250 between 1800 and 1900. Radio Uganda, UgandaBroadcasting Corporation, P.O. Box 2038, Kampala.51. Upper Volta - Two low power stations here operate on 4815 from0700-0800 and 1700-2400; and on 7230 from 0800-1700 in French andvernaculars. Radio TV Voltique. B.P. 511, Ouagadougou.52. Venda - This is a new state in northeast South Africa which justbecame independent in September. The government are setting up astation but details aren't known at this writing.53. Zaire - French and vernacufars are used by several regionalstations here on 3405, 4750. 3030. 5995, 6085, 6125, 7115. 7205, 7265and 7295. Most sign on at 0400. The Voiceol Zaire uses 7255and 11720for 24 hours a day. La Voix du Zaire, B.P. 3171, Kinshasha. RadioKisangani, B.P. 1745, Kisangani, - Radio Lubumbashi. B.P. 7296,Lubumbashi. - Radio Bandundu, B.P. 100, Bandundu.54. Zambia - Try the following times and frequencies - 6060 from0500-1615: 7220 from 0600-1530: 6165 from 0500-1700; 7250 from16130-1630; 9580 from 0630-1400: 7235 from 0530-0730: 17895 from1045-1245 (Sunday only). 9580 has also been reported around 0500.Zambia Broadcasting Service. P.O. Box RW 15, Lusaka.55. Zimbabwe -Rhodesia - Some frequencies used here are 3396from 0355 (Sun 0500) to 0545: and 8020 from 0545-1515. Both are inEnglish. Zimbabwe -Rhodesia Broadcasting Corporation. P.O. Box2696, Salisbury.

Note - All times listed in the aboveare in Co-ordinated Universal Time(UTC) which is the same as GreenwichMean Time (GMT). UTC is equal to ESTplus 5 hours. All frequencies listed arein Kilohertz. Stations often changefrequencies to suit propagation condi-tions and to avoid interference fromother broadcasters so some of theabove frequencies may change beforeyou read this. Most of them, however,will still be in use.

Before closing this month's column, Iwould like to wish all of our readers avery Happy and Prosperous New Year.

Until next month all the best and goodlistening.

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Fufl0fElect-ronics HOLD ON A SECOND, FRED, LET'S

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/ THOUGHT I HAD DISCOVERED A REAL BARGAIN WHENI SAW THAT AD FOR A "WATCH THAT NEVER NEEDSBATTERIES."

rESr EQUIPw1ENT C.

THIS LITTLE BEAUTY IS THE STATEOF THE ART IN CAPACITANCEMETERS, IT DISCHARGES THE UN-KNOWN CAPACITOR THROUGH YOUR-BODY AND THEN MEASURES HOWLOUD YOU SCREAM. r.,Fmtle I

TO BE HONEST, I'M NOT REALY UP ON ELECTRONICS,SO JUST TELL ME ONE THING; IS A MULTIMETER BIGGEROR SMALLER THAN A CENTIMETRE?

/ REALLY AM GLAD YOU LIKE THATELECTRONICSET OF DICE I BUILT, AL, BUT SOMEHOW I THINKYOU'RE MISSING THE WHOLE POINT.. .


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$1.00 Unusual Canadian and American partsand surplus catalogs. Hundreds of bargains.ETCO, Dept 087, 183G Hymus, Pointe Claire,Que.

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SURPRISE BOX! Resistor - Capacitor -Relay - Coil - etc. etc. Approximately 2500electronic parts. List over $250 for $25.All new material. Money -back guarantee.SURPLUS ELECTRO QUEBEC, 2264 MteeGagnon, Blainville, Quebec, CanadaJ7E 4H5

SPECTRUM ELECTRONICS * Qualitypcbs. All orders prepaid. Ont. Res. add7'7 PST * Box 4166D, Hamilton, Ont.L8V 4L5 * ETI 594: $1.65 * 141: $6.65148: $1.40 * 472: $8.05 * 470: $6.30471: $24.10 * Free price list.

NORTHERN BEAR ELECTRONICS, Box7260, Saskatoon, Sask. S7K 4J2. Guitareffects unit (parts only) . . .$29.95. Dig-ital Tach (parts). . .$55.00. Up/Downcounter (parts) .$39.95. MM57160

$17.95. All orders add $1.00. Sask.«Id tax.

FREE FLYER; IC's, LED's, diodes, kits,and more. ELECTRONICS, Box 68,Whitecourt, AB. TOE 2L0

SPEAKERS Galore, Individual Raw Drivers,Do-it-yourself kits, and fully assembledspeaker systems. Write to us for our free1980 catalog, illustrating our completeline. IUS ELECTRONICS LTD. P.O. Box81, Trail, B.C. V1R 4L3

WSI RADIO - SWL Radios - Ham radios -18 Sheldon Avenue North, Kitchener, OntarioN2H 3M2. Telephone (519) 579-0536. Writefor giant catalog, free of course!! (VE3EHC)

SALES PERSON familiar with test equip-ment, parts, and equipment required fordistributor and industrial sales in SouthernOntario. Car required. Salary, commission,and expenses. Call (416) 787-7367.

71

Two for One & a half SaleBABANI TRANSISTOR EQUIVALENTS, BOOK ONE & TWO.

te of

uivaQelsand 5ubs'

5.25

SeTran̂ took ofEquivalentsand Substitutes

BOOK ONE

$2.50 + 30d postage and handling

BOOK TWO

$4.50 + 30d postage and handling

TOGETHER ONLY $5.25 + 30</ P & H

DID YOU ALREADY BUY ONE OF THEM ?Then tell us the transistor number at the top ofpage 50, and enclose $1.87 + 301 for Book One or$3.87 + 30é for Book Two.OFFER CLOSES FEB. 15th. 1980.

X1(`1~41.40141~1 ` CIE`***3* E* ` E" "**"Á(****411 ** (` ***- *COOK WITH THE 741 AND 555

Back in our Feb. 77 issue, well known author R. M. Marstonwrote an extensive article on the 555 tuner IC, explaining how touse it in different ways. In May 77 he was back again with the741 Cookbook article and circuits for the 741.Well, we just cleared out our storeroom and came up with

quite a few of these issues, so we thought we'd offer themas a pair for a very special price.

Normal Back Issue Price 2 x $2.00 = $4.00Cover Price (1977!) 2 x $1.25 = $2.50

THIS MONTH ONLY $1.87 FOR THE PAIR!!!!

+ 30d postage & handling

PLEASE SEND ME THE FOLLOWING AS CHECKED.TRANSISTOR EQUIVALENTS

Book 1&2 $5.55

Page 50 transistor number fromBook1. Book2

Book 1 $2.80 Book 2 $4.80

COOKING TIME! Please send me the 741 Cookbook plus the 555 timer IC issues for $2.17TOTAL AMOUNT $ I I

Cheque Enclosed Master Charge Chargex

Card Number Expiration Date

SignatureName Address City

Postal Code Province

Please print the above information. Thank You. Mail the orders to:Two for One and a Half. Electronics Today Magazine, Unit 6, 25 Overlea Blvd., Toronto. Ont. M4H1B1

ETI Project FileUpdates, news, information, ETI gives you project support

PROJECT FILE is our department dealing withinformation regarding ETI Projects. Each monthwe will publish the Project Chart, any Project Noteswhich arise, general Project Constructor'sInformation, and some Reader's Letters andQuestions relating to projects.

PROJECT NOTESSince this magazine is largely put together by

humans, the occasional error manages to slip by usinto print. In addition variations in componentcharacteristics and availability occur, and manyreaders write to us about their experiences inbuilding our projects. This gives us informationwhich could be helpful to other readers. Suchinformation will be published in Project File underProject Notes. (Prior to May 78 it was to be found atthe end of News Digest.)

To find out if there are project notes for a projectyou are interested in, simply refer to Project Chart(see below). If there are project notes listed, theywill have appeared in Project File (note, prior toMay 78, project notes appeared at the end of NewsDigest.)

ISSUEDATE

ARTICLE

Sept 78 Audio OscillatorNov 78 Neg.

Sept 78 Shutter Timer.Nov 78 Neg.

Sept 78 Rain AlarmOct 78 CCD Phaser

Nov 78 Neg.Oct 78 UFO Detector

Nov 78 Neg.Sept 79 C,D

Oct 78 Strobe IdeaApr 79 Note:N

Nov 78 Cap Meter &Neg.Nov 78 Stars & DotsNov 78 CMOS Preamp & Neg.Dec 78 Digital Anemometer

Feb 79 NegMar 79 Note:C. D

Dec 78 Tape Noise ElimFeb 79 Neg

Dec 78 EPROM ProgrammerFeb 79 Neg

Jan 79 Log Exp Convert.Feb 79 Neg

Jan 79 Digital Tach.Feb 79 Neg

Jan 79 FM TransmitterFeb 79 Neg

Feb 79 Phasemeter & NegFeb 79 SW RadioFeb 79 Light Chaser & Neg

Mar 79 Tape -Slide SynchMar 79 Synth. Sequ.Mar 79 Tape -Slide SynchMar 79 Synth. Sequ.Mar 79 Dual Dice

Project notes can be ordered one of two ways.You can order the complete back issue, or you canorder a photocopy from the appropriate issue. Ineither case consult General Information ForReaders. If you order a copy of a constructionarticle, specify the issue where the project notecanbe found and we will include them at no cost. Youmust specify from which issue those project notescan be found.

PROJECT CHARTThis chart is an index to all information available

relating to each project we have published in thepreceding year. It guides you to where you will findthe article itself, and keeps you informed on anynotes that come up on a particular project you areinterested in. It also gives you an idea of theimportance of the notes, in case you do not have theissue refered to on hand.

COMPONENT NOTATIONSAND UNITS

We normally specify components using aninternational standard. Many readers will beunfamiliar with this but it's simple, less likely to lead

ISSUEDATE

Apr 79 Solar ControlApr 79 Audio CompressorApr 79 Wheel of FortuneMay 7J Light ControllerMay 79 AM TunerMay 79 VHF Ant.June 79 Easy Colour OrganJune 79 LCD ThermometerJune 79 Light Show Seq.

July 79 Note CJune 79 VHF Ant. 2June 79 Bip BeaconJuly 79 STAC TimerJuly 79 Two Octave OrganJuly 79 Light Activ. TachoAug 79 ,\udio Power MeterAug 79 Two Octave OrganAug 79 Light Act Tacho.Sept 79 Field Strength MeterSept 79 Sound Effects UnitSept 79 Digital Wind MeterSept 79 Up/Down CounterOct 79 Simple Graphic EqOct 79 Digital DialOct 79 VariwiperOct 79 Cable TesterNov 79 60W AmplifierNov 79 Model Train ControllerNov 79 Curve TracerDec 79 High Performance

Stereo Preamp.Dec 79 Development TimerDec 79 Logic Trigger

ARTICLE

PLEASE NOTE: WE CANNOTANSWER PROJECT QUERIESBY TELEPHONE.to error and will be widely used sooner or later. ETIhas opted for sooner!

Firstly decimal points are dropped andsubstituted with the multiplier, thus 4.7 uFiswritten4u7. Capacitors also use the multiplier nano (onenanofarad is 1000pF). Thus 0.1uFis 100n,5600pFis5n6. Other examples are 5.6pF= 5p6, 0.5pF = Op5.

Resistors are treated similarly: 1.8M ohms is1M8, 56k ohms is 56k, 4.7k ohms is4k7, 100 ohms is100R, 5.6 ohms is 5R6.

KITS, PCBS, AND PARTSWe do not supply parts for our projects, these

must be obtained from component suppliers.However, in order to make things easier wecooperate with various companies to enable themto promptly supply kits, printed circuit boards andunusual or hard -to -find parts. Prospectivebuildersshould consult the advertisements in ETI forsuppliers for current and past projects.

Any company interested in participating in thesupply of kits, pcbs or parts should write to us ontheir letterhead for complete information.

READER'S LETTERS ANDQUESTIONS

We obviously cannot troubleshootthe individualreader's projects, by letter or in person, so if youhave a query we can only answer it to the extent ofclearing up ambiguities, and providing ProjectNotes where appropriate. If you desire a reply toyour letter it must be accompained by a selfaddressed stamped envelope.

ETI Project ChartPROJECT CHART

This chart is an index to all information availablerelating to each project we have published in thepreceding year. It guides you to where you will findthe article itself, and keeps you informed on anynotes that come up on a particular project you areinterested in. It also gives you an idea of theimportance of the notes, in case you do not havetheissue refered to on hand.

Canadian Projects BookAudio Limiter5W StereoNotes N, D May 79OverledBass EnhancerMoaular DiscoG P PreampBal. Mic. PreampCeramic Cartridge PreampMixer & PSUVU Meter CircuitHeadphone Amp50W -100W AmpNote N May 79

Metal LocatorHeart -Rate MonitorGSR Mon"'orPhaserFuzz BoxTouch OrganMastermindDouble DiceReaction TesterSound -Light FlashBurglar AlarmInjector -TracerDigital Voltmeter

Key to Project NotesC:- PCB or component layoutD:- Circuit diagramN:- Parts Numbers, SpecsNeg:- Negative of PCB pattern printedO:- OtherS:- Parts SupplyT:- TextU:- Update, improvement, Mods


GeneralInformationFor Readers

Editorial QueriesWritten queries can only be answeredwhen accompanied by a self-addressed,stamped enveloped, and the reply cantake up to three weeks. These mustrelate to recent articles and not involveETI staff in any research. Mark yourletter ETI Query.

Projects, Components,NotationFor information on these subjectsplease see our Project File section.

Sell ETIETI is available for resale bycomponent stores. We can offer a gooddiscount and quite a big bonus, thechances are customers buying themagazine will come back to you to buytheir components. Readers havingtrouble getting their copy of ETI couldsuggest to their component storemanager that he should stock themagazine.

Back Issues andPhotocopiesPrevious issues of ETI-Canada areavailable direct from our office for$2.00 each. Please specify issue by themonth, not by the features you require.The following back issues are stillavailable for sale.

1977 1978 1979February mirmileisii. JanuaryMay February FebruaryJune March MarchJuly ~II AprilSeptember May MayNovember June June

July JulyAugust AugustSeptember SeptemberOctober OctoberNovemberDecember

We can supply photocopies of anyarticle published in ETI-Canada, forwhich the charge is $1.00 per article,regardless of length. Please specifyissue and article. (A special con-sideration applies to errata forprojects, see Project File.)

LIABILITY: Whilst every effort has been made to ensure that all constructional projects referredto in this edition will operate as indicated efficiently and properly and that all necessarycomponents to manufacture the same will be available, no responsibility whatsoever is accepted in respect of the failure for any reason at all of the project to operate effectively or at allwhether due to any fault in design or otherwise and no responsibility is accepted for the failure to obtain any component parts in respect of any such project. Further no responsibility isaccepted in respect of any injury or damage caused by any fault in the design of any such project as aforesaid.

Advertisers' Index

READER

SERVICENUMBER

READERSERVICENUMBER

1') Active Component Sales Page 75 11 Len Finkler Limited Page 12Arkon Electronics Page 21 12 Len Finkler Limited Page 54Atlas Electronics Page 76 13 Len Finkler Limited Page 29Audiex Electronics Page 7 17 Metermaster Page 6Audiex Electronics Page 5 McGraw-Hill Page 19Audiovision Service Page 35 New -All Electronics Page 25DCB Electronics Page 35 Omnitronix Page 51

2 Exceltronix Page 2 Omnitronix Page 54Gladstone Electronics Page 9 Omnitronix Page 61

JMC Distribution Page 29 Zenith Radio Corp. Page 49Jana Industrial Electronics Page 8

/ 1 ETI CANADA-JANUARY 1980

V4Activenentcanippam

MICROPROCESSORCHIP SETS

Part No. Price

8080A $5.95

8085 12.95

8212

8214

8216

8224

8226

8228

8238

8251

8253

82558257

8259

3.45

3.953.25

2.95

2.25

3.98

4.75

5.75

14.95

5.75

10.95

14.95

Part No. Price Part No. Price

6800 $6.95 6502 $9.956802 11.95 6504 9.95

6505 9.95

6810 3.95

6820 3.95 6520 6.956821 3.95 6522 9.956850 4.25 6532 13.95

6852 3.95 6551 13.95

1802LE 9.95 1854LE 6.951824LE 3.50 1856LE 1.95

1852LE 1.50 1858LE 1.951853LE 1.45 1859LE 1.50

LINEAR I.C.'sLM324N .59 LM741CN-8 .29LM339N .59 LM747CN-14 .59LM348N-14 .99 LM748CN-8 .39LM555N-8 .29 TBA810DAS 1.29LM556N-14 .59 LM 1458N-8 .49LM723CN-14 .49 LM3403N-14 .99LM725CN-8 1.25 1M3900N .59LM739CN-14 .29 LM4136N-14 .99

SOUND & MUSICGENERATOR I.C.

Creates almost any type of sound. from music togunshots and explosions. High level op ampoutput. 28 pin DIP. Operates from one 9V battery.With data.

"Lowest Price OfferedAnywhere"

SN76477N (.600'" centers)

SN76477NF (.400" centers)New small package

$2.49

$2.29

TEXAS INSTRUMENTSLow Profile SocketsLowest prices anywhere for thehighest quality, en unbeatable combination.Over one million pieces in stock

Contacts

8 PIN14 PIN16 PIN18 PIN20 PIN

Price

.10

.14

.17

.22

.24

Contacts Price

22 PIN .2624 PIN .2928 PIN .3440 PIN .48

NEC MICROCOMPUTERSTK80A $344.00Based on the 8080A the board has both 1KRAM and 1K electrically erasable PROMexpandable to 4K x 8 and 81( x 8 on board.Complete with keypad with 25 real keys andit bright 50fI digits for display.

1 r ZilogZ8001 $195.00 16 BitCPJ with segmented address space

to 8 Megabytes.Z8002 $150.00 16 Bit CFU with non segmented address

space to 64K bytes.Z8000DB $1500.00 A complete single board Z8000

microcomputer system. Contains theZ8002 microprocessor, 16K words ofdynamic RAM, 2K word monitor PROM,dual serial interfaces, lour counter/timersand 32 programmable parallel I/O fries.

All Products Stocked in DepthLargest Zilog Inventoryi

METAL POWER TRANSISTORSHomotaxial - Best Quality

2N3054 .65 60V NPN T0662N3055 .69 70V NPN TO -32N3442 1.50 160V NPN TO -32N3771 1.95 50V NPN TO -32N3772 1.95 100V NPN TO -32N3773 2.50 160V NPN TO -3

Universal SCRC106D .34 400V 5.0 AMP TO -220

EPROM'SC27081Kx8 450nsTMS271616K (2K x 8) 450 ns(3 power supplies) T.I. Version

C2716/TMS251616K(2Kx8) 450 ns(Single 5V supply - Intel version)

$ 995

$2495

$2995

6 _ a_ _ .. A _ m .All title _Special of the Month 1

4K STATIC RAM2114 L Low Power 54.954K (1024 x 4) 300ns Jgam m Pm WOW elite - p111a AAA

1980 IC MASTERJUST RELEASED over 2700 PAGES

Complete integrated circuit data selector. Master guide to the latestIC.'s including microprocessors and consumer circuits. 45,000device types listed. 5,000 new device types added. Complete newsection on MPU boards & Systems.

Free Quarterly Updates 569.95

Z80 -CPU 2.5 MHz $ 9.95Z80A-CPU 4.0 MHz 11.95

Z60 -P10 2.5 MHz 7.20Z80A-P10 4.0 MHz 8.40

Z80-CTC 2.5 MHz 7.20280A-CTC 4.0 MHz 8.40

Z80 -DMA 2.5 MHz $26.85Z80A-DMA 40 MHz 33.60

080-SIO/0 2.5 MHz 36.00Z80A-S10/0 4.0 MHz 39.50

Z60-SIO/1 2.5 MHz 36.00180A-SIO/1 4.0 MHz 39.50

Z80-SI0/2 2.5 MHz 36.00Z80A-SIO/2 4.0 MHz 39.50/

MOS MEMORIESPart No. MOS Static RAM's21011K(256 x 4) 350ns 22 PIN2102LFPC1 K (1K x 1) Low Power 35ons 16 PIN2102LHPC1K (1K x 1) Low PowerHigh Performance 250ns t6 PIN2102.1PC11(11K x1) 450ns 16 PIN2102-2PC1K (1K x 1) 65Ons t6 PINP2111-251K 1256 x 4) 250ns 18 PINP2112-351K (256 x 4) 350ns 18 PIN

MOS Dynamic RAM's416.516K (16K x 1) 300ns 16 PINTMS4060-3041( (4K x 1) 300ns 22 PINTMS406O-2041( (4K x 1) 200ns 22 PIN

UART'sAY5-1013A0 to 40K BAUD 40 PINAY3-10150 to 30K BAUD 40 PIN Single 5V supply

1K CMOS RAM

Price

51.95

1.19

1.29

0.94

0.89

2.25

2.25

9.95

2.95

3.95

4.50

5.50

5101 3.951K (256 x 4) 450ns 22 PIN Low Power

4K CMOS RAMP4315 -45L 4K 141( x 1) 450ns 18 PIN 14.95

SHIFT REGISTERS3341PC FIFO 700 KHz3341APC FIFO 1 MHz3342PC 64 Bit Shift Register3347PC 80 Bit Shift Register

ECL RAM10410ADC/HM2106 Special 1.95256 z 1 Bit Fully Decoded 15ns 16 PIN

4.95

5.504.954.95

MICROCOMPUTER BOARDS

,i, Rockwell InternationalAIM65 $431.25As a learning aid AIM65 gees you anassembled, tested and wa-ranted R6502based microcomputer sysem with a full sizedkeyboard, an alphanumerc 20 characterdisplay and uniquely, an alphanumeric20 column thermal printer An on boardAdvanced Interface Monit.r programprovides extensive control and programdevelopment functions 11- RAM.

Sy'nertek' SYM-1Fully assembled. tested, documented and expandable. Powerful 655022758-13J

microprocessor. 6 -digit hex LED display. KIM -1 hardware compatibility.Single plus 5V power requirements.

Texas Instruments TM990/189 $383.00UNIVERSITY MODULEA complete learning aid that in conjunction with the Tutcial Text oilershands on experience with microprocessors. I/O. memory and assemblylanguage programming. Offers advanced features such as 45 kevalphanumeric keyboard, a powerful instruction set, multiply and dividevectored interrupts, single bit I/O manipulation parallel I -0 and7 addressing modes.

_.E.D. LAMPSLED209 T -I 3 mm RedLED211 T -t 3 mm GreenLED212 T-1 3 mm Yellow

LED220 T-1,4 5 mm RedLED222 T-1% 5 mm GreenLED224 T -t% 5 mm Yellow

DISPLAYSFN0357 375' Common Cathode-ND367 .360' Common Cathode

(high brightness)FND500 .500' Common CathodeFND507 500' Common AnodeFN0560 .500- Common Anode

(high brightness)FND567 500' Common Cathode

(high brightness)DL704 300' Common CathodeDL707 .300' Common AnodeDL747 630 Common Anode

ISOLATORSLD74 Dual Opto Isolator.L074 Quad Opto isolatorMCT6 Dual Opto Isolatori IL111 Opto Coupler.1N26 Opto Isolator4N28 Opto Isolator.iN29 Opto IsolatorÁN32 Opte Isolator

1500V1500V1500V1500V2500V

500V2500V2500V

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MINIMUM MAIL ORDER 510.00Add 52.00 to cover postage and handling

PRICES ARE IN U.S. FUNDS. F.0 B. CANADAFederal Sales Tax (Vol and ApplicableProvincial Sates Tax Extra.

If payment to be made in Canadian Funds anapproximate 20% conversion rate will be added attime of purchase.

5651 FERRIER ST. 4800 DUFFERIN ST.MONTREAL, QUEBEC DOWNSVIEW. ONTARIOH4P 2K5 M3H 5S9Tel.: (514) 731-7441 Tel.: (416) 661-1115

LARGE INVENTORY AT ALL LOCATIONS

STORE HOURS:Mc nday to Wednesday 8:30 am . 6.00 pmThursday and Friday 8:30 am - 9.00 pmSaturday 9 00 am -- 5:00 pm

BAXTER CENTRE1060 BAXTER ROAD01TAWA. ONTARIOKee 3P2TeL 16131 920-9471

3070 KINGSWAYVANCOUVER. B.C.059 5J7Tel 1604) 438.3321

master chajl


Challenge any wavewithelectrifying confidence.

Now you can say good -by to waveformjitter and triggering instabilities, with the newB&K-PRECISION Model 1535 dual -traceoscilloscope. The 1535 offers a full comple-ment of features and high performance specsto more than meet your challenges.

The B&K-PRECISION 1535 is one of thefew dual -trace scopes available with an alter-nate triggering mode. In this mode, the triggersource is sampled from channel A or channelB on alternate sweeps. With alternate trigger-ing, you'll be able to display two stable signalsthat are unrelated in frequency. As in muchmore costly dual -beam scopes, the use of onechannel is not dependent on the triggeringsignal at the opposite channel. Many othertrigger source positions can be selected.

Other significant features include variablehold -off, for accurate display of pulse trains;

single sweep, for non -repetitive waveforms;and even UNCAL "reminder " LEDs forsweep and input level verniers. A video syncseparator is standard, for use with videocircuits or computer terminals.

With 2mV sensitivity and flat 35MHzbandwidth, the 1535 will display most anysignal you're likely to encounter. Forobserva-tion of the leading edge of fast digital pulsesignals, a signal delay is built-in. The 1535 isespecially well suited for microprocessor ,*

work.Also new from B&K- PRECISION is the

1520 dual -trace scope. This 20MHz scopeoffers many of the features found on the 1535.

1

It's a cost-effective substitute for more costlyscopes, when a 20MHz bandwidth is all that'srequired. The 1520 offers a 10 times sweepmagnifier, 5m V/cm vertical sensitivity andindependent chop/alternate display selection.

The 1535 and 1520 scopes are availablenow. For immediate delivery, a ten-day freetrial or in -plant demonstration, contact yourlocal B&K- PRECISION distributor.

DYNASCANCORPORATION

6460 W. Cortland Street Chicago, IL E0635.312/889-9087

In Canada Atlas Electronics LimitedCircle No. 15 on Reader Service Card.

8&K -PRECISIONModel 1535 - $ 1837Model 1520 - $ 1419Other osci/loscopes

from $352

e xceltronix - worldradiohistory.comfree 555 timer ic with purchase of any of the following books:...

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