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Technology &. The Solar Challenge Racers SERVICING -VINTAGE RADIO - COMPUTERS -AMATEUR RADIO - PROJECTS TO BUILD A-3000 REMOTE CONTROL UNIT MODEL 1133 REMOTE ACCESS TELEPHONE/ ANSWERING MACHINE You can control just about anything with this Remote Control Transmitter/Receiver. Eg. TV:S, Stereo's, Alarm:S etc. * N.0./N.C. relay output up to 5 amps. * Receiver operating voltage: 12V DC. * Complete with two remote keys. Telephone Features: Tone/Pulse switchable. Last number redial. Ringer on/ off switch. Lighted dialing keypad. * Operating distance: 10 meters. was$109.95 now $89.95 KASPAROV POCKET PLUS CHESS COMPUTER Answering Machine Features: Single micro cassette. VOX recording. Call screening. Toll saver function. Tone. remote control to access messages from touch tone phones. TELECOM APPROVED * 8 levels of skill to Advanced from Beginner to Intermediate. * You set the level of help required and then play against the computer. JIC-678N (LPG,LNG) o)l.l)l)(J(J7, MS-110 SWR METER GAS LEAKAGE _....1 ~ ~ for 27MHz rroR ~ -~ ) ~*SWRMeter. DETEc I · ~4"> J =MT _ KTIJO ,. . * *Power Meter. * Detects Propane, Butane and , ~ AM Modulation Meter. * ~~~l~~~s~:f:~d audible alarm. * N.O./N.C. output for alarm systems. * 12 volt DC operation · UMYll5AL -'"" F-t • -,i ~ - ~ ~ r--',-... !. ~ ~ ~ Sate guard your family and your possessions.Gas leakage can be fatal Ideal tor the car, caravan, boat kitchen, etc. ~ * 1, 10, 100 watt switchable. 0 The TELE-ART RC700 Universal Remote Control Unit can replace the infra-red remote controls of up to five audio/video components br, simply learning and then mimicking their remote con rot command codes. This eliminates the confusion of which remote control to use and does away with the clutter of too many remote controls. ~ "'\0 n.'.~~\I ~~.,. "'~~ ~(W 0 t:, ,... ~ • ._ * Can memorize up to 1T commands per component, \ . ~ s tots/ of 85 commands. ,; for LCO display indicating function in use snd clock. * ~ii;:i:;;,;,~':,i;~~;atically turn ON/OFF any one of ~ ,; Countdown timer, can automatically turn ON/OFF t ◄ ~re ~:mO:rff.'e com;;;; $99.95 ' <~~ __, .• Limited Stocks ! only $39.95 <~ RG-58 52 Ohm ;. ·.~ ~v •.•.•:.•• •1 0 0 ~ J,. ~~ 0 now only $69.95 * FM Deviation Meter. ~ * Antenna Matcher. r ~ ■ -= ~,~ ~ , ,,.. , ~ ...._ ~ ,t[)fl([()~ COAX CABLE ~r * Suitable for CB (HF) use, ooN'roo;Lc;_;~~e;.;;;m;,;~~i: /ll/$#11/l 4 DIGIT COMBINATION LOCK KIT AVM -1 AUDIO/VIDEO MIXER This simple 4 digit combination lock has many applications,such as accessing alarm systems, electronic doors, ignition killers, or just about anything * Operating voltage: 11-30V DC. * Provision for battery back-up. * 12V door strike to suit .. $39.95 Now tht1rt1 's a simple and int1xpt1nsive way to add narration, sound effects, and background music to your vidt1o's after you have been out in tht1 field and shot them. rhis easy to uat1 mixer enables one microphont1 and up to three audio inputs to be added to Iha sound track on the video tape. Ideal for the home movie buff. Each input has its own sept1rate audio volume control for fading music etc. in and out as well as a mastsr control for output /t1vel onJ $39.95 ll-<.111-<.•.......~■.: t=.1.............1.... 1 COS-5100TM * 100MHz. * 3 channel w ith delay. * 5mV / DIV to 5V /DIV, DC to 100MHz. * 2ns/DIV to 0.5s/DIV, both A and B. * Includes 2 x 1:1 10:1 probes. * 2 year warranty. $285a00 lncl tax. Oscilloscopes COS-5060TM * 60MHz. COS-5041TM * 5mV / DIV to 6V /DIV , DC to 60MHz. * 5ns/DIV to 0.6s/DIV, both A and B. * Includes 2 x 1:1 10:1 probes. * 5mV/DIV to 5V/DIV, DC to 40MHz. * A timebase: 20ns/DIV to 0.5s/DIV,(maln). COS-5020TM * 20MHz. * 2 channel. * 5mV/DIV to 5V/DIV, DC to 20MHz. * 3 channel with delay. * 40MHz. * 2 channel with delay. * 2 year warranty. * Includes 2 x 1:1 10:1 probes. * 20ns/DIV to 0.5s/DIV. * Includes 2 x 1:1 10:1 probes. * 2 year warranty. $f37a00 $8Baoo $1Boaoo lncl tax. * B timebase: 0.2us/DIV to 0.5ms/DIV,(delayed). * 2 year warrany. Inc/. tax. Inc/. tax, 10 volt AC Plug Pack * * * 10 volt AC o 1 amp. Complete with 2.1mm DC type plug. To suit many modems requiring 9 volt AC supply. ,,, A VERY RARE PRODUCT! DB-25 GENDER CHANGERS . * NEW 7HIN" STYLE. ~1~ls· * Only 22mm long. * Male to Male. 0-Q ,q,"1; * Female to Female. Variable AC (Iual-timer E L E C T RO NI C Transrorrners * HSN-0103 * HSN-0203 * HSN-0303 0-250V, o SA 0-270V, o 7 A 0-270V, o 13A PLUS CLOCK $159.00 $187.00 $314.00 A 24 hour dual timer/clock with,· 2 count-down timers, An enclosed, table-top variable transformer with 4mm captive head type and seperate earth connectors. Largr, voltage control dial and a clearly marked scale, housed in a steel case. Only $8.50 ea. MB-3 SPEAKER MOUNTING BRACKET by •ARISTA• FULL 12 MONTHS WARRANTY RS232 LINE BOOSTER Medium to heavy duty two platform bracket designed tor mounting speakers to walls, desks, ceilings, etc. Allows speaker lo be rotated a full 360 deg. as well as swivelled up and down. 2 preset memories. count-up timer and clock. Ideal for sports, maetings, medication, cooking etc. Displays Hours, Minutes and seconds. Built-in alarms. Having trouble with long RS232 cable lines and then finding out your output level has dropped and your not getting enough signal down the line? II so, then you need a RS232 Line Booster. Ths Line Booster can double your cab/a length. Requires 12V DC supply o 100mA ... $13.95 PIR-30 PASSIVE INFRA-RED DETECTOR * 12 meter range o 90 deg. * Walk test indicator. * 8-18V DC operated. * N.C. relay output. * N.C. tamper output. * save $20.00 now only only only $49.95 $49.95 $29.95 PUICJ~S NJ~\\T LO\\T PUICJ~S N1~\\T LO\\T PUIC1~S NJ~\\T LO\\T PUICJ~S N1~ J,f1 FLUKE 87 FLUKE 85 FLUKE 83 FLUKE 77 FLUKE 75 FLUKE 73 only $19.95. $676.00 $560.00 $466.00 $345.00 $258.00 $160.00 S~lDIUcl 1\\(YI .M~lN S~l[)IUcl 1\\0rI 1\\~lN S~lDIUcl .Mo<\. AVS30 VIDEO TRANSMITTER Ideal for watching a video in the bedroom. kitchen etc. without having to move your complete VCR system or having long extension cables runing from one end of the house to the other. Output channel: UHF30 Transmitting distance: 10 mtr. Complete with connecting cables and power supply. * * * MOTORAD TL-301 TIMING LIGHT with DIRECT READING ADVANCE SCALE The TL-301 Advance Scale design is tor easy one-handed operation of timing advance function. Leaves other hand free to get access to those hard to see indicators. Measures timing accurately up to 6000 RPM . Test timing on all 12 volt conventional and electronic ignition systems .... 4, 6 or 8 cylinders, including rotary motors * * was $110.00 only $89.95 QO.C. approved CITIZEN ED-3800 ELECTRONIC DIARY Store Telephone No;s. Names and Memo function. Schedules. 12/24 and Alarm, World Time, Calender. Metric Conversion. 10KB memory. 3 llnes with 18 * * Addresses, hr. Clock Calculator. char-acter-s. CITIZEN ED-4500 CITIZEN ED-7800 Telephone Directory with Names and Addresses, Calender. Memo, Schedules. Calculator. Metric Conversion. 32KB memory. 6 llnes with 13 characters. Telephone Directory, Schedules, Memo, 12/24 Clock with Alarm, World Time, Calender, Metric Conversion. Currency Exchanger, PC Link. 32KB memory. 6 lines with 32 characters. ELECTRONIC DIARY * * ii . * 147 X 62 X 18mm only $125.00 now $79.95 * 132 X 65 X 13mm David Reid Bectronics ■ o nly $169.00 ELECTRONIC DIARY * * IE!!:J 111111 * 154 X 82 X 19mm only $275.00 127 York St. SYDNEY 2000 PH: (02) 267 1385 P.O. Box Q103, SYDNEY 2000 FAX: (02) 261 8905 SAME DAY MAILORDER DESPATCH* CIC ~ /n11ffl111iontI/' Poot ond Pockln9 $5 - $25 ........ S3.00 $26 - $50 ...... S5.00 $51 - $100 .. .... S6.00 $101 - $499 .... S8.00 $500 • ............ FREE l~I II [I t"iil1 ~.1.:.1111 , · -· April 1991 HAD ENOUGH OF that pitiful whine from your model steam loco? This circuit makes a realistic chuffing sound that paces the loco speed. See p.22. FEATURES 6 The World Solar Challenge by Gerry Nolan The technology behind the race 16 Canon's New Still Video System by Bernard Malone A marriage of CCD & floppy disc technology 64 A Practical Approach To Amplifier Design, Pt.2 by David Eather Driver transistor selection & heatsink requirements 72 Hewlett Packard's Model 54600 100MHz CRO The first of a new generation PROJECTS TO BUILD 22 Build The SteamSound Simulator by Darren Yates THE CONSTRUCTIONAL details for our new garage door controller begin on page 30 this month. We also include a few installation hints. Give your model railroad some real atmosphere •. ,,._,r 30 Remote Controller For Garage Doors, Pt.2 by Branco Justic Construction plus installation 53 Simple 12/24V Light Chaser by Darren Yates Four channels plus variable chase rate 56 Synthesised AM Stereo Tuner, Pt.3 by John Clarke Final article gives the alignment details "I\Wlf• 1.-001 SPECIAL COLUMNS 36 Vintage Radio by John Hill Converting an Airzone to AGC 40 Serviceman's Log by the TV Serviceman Mystery, mystery & frustration 74 Computer Bits by Jennifer Bonnitcha Playing with the Ansi.sys fil e ~91.._ THIS MONTH, the Serviceman took a wee peek at a Mitsubishi TV set made in Scotland. It frightened him. His story starts onp.40. 78 Amateur Radio by Garry Cratt The Easytune FSK indicator for HF transmissions 86 Remote Control by Bob Young How pulse code modulation decoders were developed DEPARTMENTS 3 Publisher's Letter 4 Mailbag 70 Circuit Notebook 81 Product Showcase 90 Back Issues 2 SILICON CHIP 92 Ask Silicon Chip 94 Subscription Page 95 Market Centre 96 Advertising Index THIS LIGHT CHASER has four separate channels, variable chase rate & can operate from 12V or 24V DC. See p.53. Publisher & Editor-in-Chief PUBLISHER'S LETTER Leo Simpson, B.Bus. Editor Greg Swain, B.Sc.(Hons.) Technical Staff John Clarke, B.E.( Elec.) Robert Flynn Darren Yates Reader Services Ann Jenkinson Advertising Manager Paul Buchtmann (02) 979 5644 Mobile: (018) 28 5532 Regular Contributors Customer service - opportunity knocks As I sit down to write this month's "Publisher's Letter", I have just finished talking to one of the many sales representatives who come to visit us every month. Not uncommonly, these reps are interested in tapping into the lucrative electronics hobbyist market because they see the apparent success of the big operators, some of whom advertise in this magazine. But while they are attracted by the thought of new business they are very much put off by the thought of having to sell directly to the public. They somehow wish to gain some of the business of firms like Dick Smith Electronics or Jaycar but without making any contact with the actual customers. Unfortunately, I don't have much sympathy for this view. For we also hear a lot from readers or small firms who wish to buy from component distributors who just won't deal with them. Quite simply, these organisations are turning away business. And, in the current economic climate, they are turning away the very best business of all - it is called "cash sales". Now while having to set up a cash sales counter may cause a problem for some firms, just think of the advantages. There is no need to invoice customers. There are no bad debts with cash sales. The cash comes in, often before the company has to pay for the goods it is selling. Need I go on? Some of the firms in question also worry about the high cost of providing each individual sale. They don't wish to make a $5 sale that they say costs them $15. Well, does it really? The easy way around that problem is to stipulate a minimum value cash sale which might be $10, for argument's sake. Now while the individual $10 sale might still be regarded as a loss situation, at the end of the month, a bunch of these sales might make a substantial contribution to overheads and might not be such a loss after all. Also it might just be the case that the firm has not worked out the true cost of its conventional invoiced sales. The bottom line is service to the customer. If customers know that components are on sale from a firm they will eventually buy from that firm. And you never know when a previously small customer may decide to place a big order, solely on the basis of the good service he has had in the past. On the other hand, if he's had the cold shoulder in the past, why should he place the big order? Is that how you think? I know I do. Leo Simpson Brendan Akhurst Jennifer Bonnitcha, B.A. Garry Cratt, VK2YBX John Hill Jim Lawler, MTETIA Bryan Maher, M.E ., B.Sc. Jim Yalden, VK2YGY Bob Young Photography Glen Cameron Editorial Advisory Panel Philip Watson, MIREE, VK2ZPW Norman Marks Steve Payor, B.Sc. , B.E. SILICON CHIP is published 12 times a year by Silicon Chip Publications Pty Ltd. All material copyright ©. No part of this publication may be reproduced without prior written consent of the publisher. Printing: Magazine Printers Pty Ltd, Rozelle, NSW 2039; Macquarie Print, Dubbo, NSW 2830. Distribution: Network Distribution Company. Subscriptioa rates: $42 per year in Australia. For overseas rates, refer to the subscription page in this issue. Liability: Devices or circuits described in SILICON CHIP may be covered by patents. SILICON CHIP disclaims any liability for the infringement of such patents by the maJ7ufacturing or selling of any such equipment. Editorial & advertising offices: Unit 39, 5 Ponderosa Pde, Warriewood, NSW 2102. Postal address: PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 979 5644. rax (02) 979 6503. ISSN 1030-2662 APRIL 1991 3 MAILBAG Bouquets for the high energy ignition system I have just completed assembly of the 25th High Energy Ignition kit and I wish to compliment you for making the improvements that were incorporated in the version described in the May 1990 issue . In particular, changing the 75V 1W zener diodes to 5W units puts an end to the premature failures in the original unit.. I use the older version (described in the May & June 1988 issues) as a demonstration for our apprentice fitter diesel students, as an introduction to simple electronics. Usually at least two students per block purchase the bits and fit it to their vehicles. Having to assemble it teaches them how to recognise values of resistors and gives them a basic understanding of the function of diodes, ICs, transistors and capacitors. And last but not least, how to solder. Thanks again for the improvements. T. Merucci, 8 Mile Plains, Qld. Does green dye absorb laser light? Thanks for the excellent article on CDs and green pens in your December 1990 issue. I have noted that other magazines have also indicated that "green pens" have no demonstrable effect on the music reproduction from CDs . However, I have not seen any comparison between the absorption spectrum of the green dye used in these pens with the IR wavelength used in the lasers that scan CDs. M.J. Vincent's comment in Mailbag (February 1991) is the closest suggestion I have come across to comparing the dye's absorption spectrum with the IR wavelength used . Would it be possible to measure th e absorption spectrum of the green dye and to report your findings in SILICON CHIP? (Organic Chemistry Departments in local universities should have suitable IR spectrometers to do the job). The wavelength of the IR radiation from the scanning lasers in CD play4 SILICON CHIP ers ~hould be available from published technical data. The obvious statement is that if the green dye does not absorb the IR wavelength used, then the pens cannot possibly work. C. G. Hodgson, Wyong, NSW. • We have been advised by the distributors of one of these pens that they have figures on the absorption spectrum of the green dye used in these pens. Apparently, the green dye does absorb the infrared light from the lasers. However, even if the green dye does absorb the laser light, that does not mean that the pens work. Fluorescent lights do have drawbacks I have just read your February editorial concerning fluorescent lights. I agree with your comments about the poor quality and impracticality of many modern incandescent light fittings , but I do not support your statement to the effect that the declining popularity of fluorescent lighting is entirely due to some sort of conspiracy campaign by the trendy press. While it is true that, in the past, people have disliked fluoros because the only fittings available were unattractive to look at, that wasn't the only objection! What about the horrible starter circuits they almost universally used? Fluoro fittings are also prone to buzz and hum and the tubes often develop an annoying 50Hz flicker long before they're worn out. It's true that you can now get fittings in all sorts of attractive shapes, and the new electronic ballasts alleviate the other problems, but there is still a fatal (and little understood) flaw in fluorescent lighting - they cannot produce true white light! True white light such as that produced by an Xenon discharge tube has a uniform frequency spectrum. That is, all wavelengths of light are equally represented. When your eye sees this type of light, the red, green and blue cone cells on your retina produce specific responses which your brain has learned to interpret collectively as the "colour" white. SILICON CHIP, PO Box 139, Collaroy Beach 2097. Now, while you can produce exactly the same sensation by mixing together suitable proportions of red, green and blue light, the illusion of white light so produced only works for white objects! For an extreme example, imagine a vivid yellow dye which reflects strongly at a particular yellow wavelength and absorbs all others. When this is illuminated by true white light, the wavelength it reflects will stimulate both the red and green cones on your retina, a situation your brain interprets as "yellow". Now suppose we synthesised white light by mixing red, green and blue light from lasers (each of which produce only a single wavelength) . Under such light, white objects would still look white, but the yellow dye would look black, because there would be no light of its particular wavelength present! The fluorescent powders used in fluorescent tubes have a very "lumpy" frequency spectrum, and the manufacturers normally use a mixture of different colours to produce the illusion of various shades of"white". But it is not really white and the "holes" in the spectral response produce unpredictable results with coloured substances, perhaps not as extreme as the example given above, but enough to make people feel there's "something wrong". That's probably the main reason people still don't like fluoros. It's worth noting that in the film and TV industries, fluorescent lighting would represent an enormous saving in both power and installation cost. The fact that the preferred light source is still tungsten, followed by HMI discharge lights, implies that they must know something you don't! K. Walters, Lane Cove, NSW. • It is true that most fluorescent tubes do have a very lumpy light emission spectrum. However, those manufactured for special applications such as art galleries have a much more even (whiter) spectrum, as well as having low ultraviolet emission. Voice recognition for the deaf I have a deaf fri end who is 87 years old but otherwise in good health. I am trying to find a way to help him. In my copy of the USA magazine "Monitoring Times", November 1990, there is an article entitled "DSP: A New Technology For Your Shack or Listening Post". It explains that through a Digital to Analog Converter and a Digital Signal Processing microprocessor and out through an Analogue to Digital Converter, it is possible to accept audio from a radio or TV and with an interface and control, print it out or view it on a computer screen. For several months now I have been trying to find a system which would allow my friend to do just that, using this system to read out the content of radio or TV programs. I have just about exhausted all avenues in New Zealand, with many people telling me of the big problems of speech recognition and cost of any equipment to do this. Others do not know what I am talking about. I decided to write to ask if you or your readers can throw any light on a system of audio recognition. Initially, I was thinking of a "Video Phone" that would allow the deaf to make phone calls and I am sure that I have seen such a system described. The following companies are li1-ted as manufacturing the DSP system: Advanced Electronic Applications, 2006 196th St SW, Lynwood, WA 98036, USA; LL Grace Communications , 41 Acadia Drive, Voorhees, New Jersey 08043, USA; DRSI, 2065 Range Road, Clearwater, Florida 346'25, USA; and Intellhome, 571 Responsive Way, McKinney, Texas 75069, USA. I wrote to all these companies on 13th January but to date no reply. Perhaps you or your readers can find a way to help my friend and other deaf people in this regard. D. H. Rout, Christchurch, NZ. Criticism for bias against FM I've been enjoying Mr Young's Remote Control column for some time now. However, I'm moved to put pen to paper over the many significant errors in the December issue. His admitted bias towards AM is fine and I'd agree that the theoretical advantages of FM over AM are rarely achieved in practice. However, he then goes on to "prove" his case against FM with many superlatives such as "much more expensive ... much more complex ... much higher price". None of these assertions stand the most cursory examination. For example, examine the prices of AM and FM sets. In the USA they are within 10% of each other. Here in NZ, a Futaba 4 NBL AM set costs $274 and the FM version costs $274.60. Maybe it's my poor command of the Australian dialect of English , but I suspect that 60 cents would not qualify for "much more expensive"! Granted, crystals are more expensive at $16 compared with $9 for AM sets, but this does not reflect itself in the system prices. The complexity he quotes is also incorrect. Firstly, I challenge him to show me a simpler AM transmitter than the RCM&E FM one. Secondly, his "simple" AM receiver has a component count of 61. Inspecting the circuits of several similar quality FM receivers, I find from 34 to 66 components. The average is 53 components. The capture effect he quotes as a serious disadvantage can be easily demonstrated in the lab, but has never been a problem in the "real world" of the flying field, at least in the 13 years I've been involved in FM R/C sets. He then goes on to overplay the difficulty of oscillator design in FM sets. From personal design experience in this area, I just cannot agree that it is as difficult as he portrays. Likewise the designers at Futaba, JR, Airtronics and Multiplex appear to find it easy enough to design reliable and cost-effective oscillators. Don't get me wrong, there is nothing wrong with a preference for AM sets, but the case should be argued from a position of logic and with fac tual statements. He has done neither. And as a final observation, his statement that 30MHz is about the limit for fundamental crystals is also wrong. A number of vendors offer fundamentals to 70MHz and at least one offers AT fundamentals to 300MHz. Barry T. Lennox, Wellington, NZ. Bob Young has his say Errors? Differences of opinions certainly, but errors; definitely not. When I wrote that article I knew with abso lute certainty that I was approaching a Sacred Cow and that great care was in order. I also knew I would get flak because of my stance. I therefore had the copy checked by an engineer well versed in the design and service of NBFSK R/C systems. I was of course absolutely correct in my expectations of flak. I did not, however, expect to get that flak from as far afield as New Zealand. Nice to know we circulate widely. Anyway, thanks for the letter. As usual , I always learn something from these exercises. The crystal thing surprised me and shows just how rapidly electronics is advancing. There are indeed vendors supplying fundamentals to 300MHz and interestingly enough Garry Cratt's article in the February 1991 issue shows an MMIC oscillator using a fundamental crystal at 330MHz. What you neglected to mention however is that these crystals are manufactured under a new chemical etch process and are even more expensive still. My comment regarding fundamental crystals in the standard price range having a limit of around 35MHz still holds (at least in this country). However, as the world 's worst designer of frequency multipliers, I certainly welcome news of crystals being available at 300MHz and for that news I thank you. From here on your letter loses me. You have in inverted commas, which indicates a direct quote, a string of superlatives which I just simply cannot find in my article; "much more expensive ... much more complex ... much higher price". Now "much more expensive" means the same as "much higher price" . What I did say is "FM sets are expensive to purchase"; quoting from the October 1990 Futaba (Aust.) price list: AM 4ch set, $225: FM 4ch $275. continued on page 89 APRIL 1991 5 World Solar Cha/le Advances Electric Whether people think about it or not, the vehicles competing in the recent World Solar Challenge were some of the most advanced electric vehicles ever produced. They are extremely efficient and quite fast, as this report of the race indicates. ROUND 350 BC, when Alexander asked Diogenes if he lacked anything, Diogenes replied: "Yea, that I do; that you stand out of my sun a little". Perhaps he was only speaking metaphorically but, to this A "Spirit of Biel 11" - the winner of the 1990 World Solar Challenge. It covered the 3007km route from Darwin to Adelaide in just over 46 hours at an average speed of 65km/h. 6. SILICON CHIP day, we can't be sure that Diogenes didn't mean that Alexander should get out of the way of the sun shining on his solar powered chariot. Nothing much has changed. As solar vehicles become more popular, more people are bound to be asked, with varying degrees of politeness, "excuse me please old thing, would you mind stepping out of the sunlight for a moment or two?" Also unchanged since those times is the amount of energy from the Sun reaching the Earth's surface, around lkW /m 2 • It may be as much as 1.3kWI m 2 on some days because of energy reflecting back from clouds but this is not something to rely on. The total amount of available energy will of course be altered by a number of factors, such as: season, latitude, time of day, cloud cover, air pollution and so on; all of which we have little direct control over. What can be controlled, or ·at least improved upon, is the percentage of the available light energy that is converted to electrical energy to drive a vehicle and/or be stored for later use. And this is what the World Solar Challenge (WSC) is all about - it provides the impetus, through competition, for contestants to improve every aspect of their vehicle design and, most importantly, the efficiency with nge Vehicles · which the Sun's energy is converted for use. The second World Solar Challenge started in Darwin at 8:00am on 11 November, 1990 and finished 3007km and 46 hours, 7 minutes and 51 seconds running-time later, when the Spirit of Biel II crossed the line in first place with an average speed of 65.Zkm/h. By GERRY NOLAN. The elegant "Southern Cross". Its multiple-curved panels are made possible by the use of amorphoussilicon photovoltaic cells. Experience pays off During the race, it became apparent that the teams which competed in the first WSC in 1987 were at a distinct advantage, the Spirit of Biel team being a case in point. In 198 7, after losing five hours in Alice Springs to repair damage caused by what was arguably the world's first collision between a solar car and a conventional car, the first Spirit of Biel gained third place. This time they won it. This emphasises the tremendous value of the World Solar Challenge and the similar events that are proliferating around the world, as stimulus to the development of practical solar electric vehicles. Not everyone, however, learnt from their experience. Aquila, the "secondhand" Northern Territory University's 1987 Desert Rose, rebuilt by a team from Dripstone High School in Darwin, had a drama when a bolt fell out, allowing one front wheel to collapse the same bolt that had fallen out and caused the same drama in 1987! Ironically, the new Desert Rose had a similar problem when a nut worked loose and let one of its front wheels fall off just after the 1990 start. But these were the exceptions most of the experienced teams performed better the second time around, in particular Hoxan's Phoebus, which took over 153 hours the first time but, Highly efficient solar cells are wired in a 'shingle' type arrangement so that the entire surface of the panels is photoelectrically active. The shingle strings are then assembled into modules. in 1990, finished in 57 hours 21 minutes to gain fourth place. Making solar cars faster Most SILICON CHIP readers will al- ready have a fairly good idea of the factors influencing solar electric vehicle performance. What we are going to look at more closely here is the progress that has been made in these APRIL 1991 7 Integration of the solar modules into the vehicle structure. The final solar generator is over 17% efficient and, with a bright Sun, delivers 1300 watts, making it the most efficient silicon gener.ator ever built. areas since 1987. In particular, we'll look at the progress made towards more practical solar electric vehicles. The most obvious factor influencing solar vehicle design is of course the solar panels themselves - their physical characteristics and their efficiency. Other factors include, in roughly descending order of importance: battery performance, electrical power transmission efficiency, mechanical power transmission efficiency, body weight and aerodynamic efficiency, vehicle stability, rolling friction and; the one that can assume the most importance at any time, structural integrity and reliability. Solar cell efficiency Wait a second - if the energy from the Sun is free and virtually limitless, why worry about efficiency? Well, of course, it's a weight and space problem. If we could use an unlimited area of solar cells, without worrying about the weight, the efficiency with which the solar energy was converted to electrical energy wouldn't matter. Obviously, in the case of a solar powered vehicle, we are limited. 8 SILICON CHIP Solar, or photovoltaic cells (PVs), were first developed in 195 7 and NASA was the first organisation to undertake large scale research and development because it needed them to run the batteries in satellites. Now solar arrays are as much a part of satellites as are wheels on cars. Various combinations of chemicals have been used in the search for higher efficiencies but they have narrowed down to a few that either work better than the others or are not prohibitively expensive. Silicon cells have proven to be the best option so far and vary in efficiency from 8-12% for amorphous cells, 12-16% for monocrystalline and more than 18% for laser grooved cells. Hoxan Research Laboratories, which fielded Phoebus III in the event, claim 19.3% efficiency for their mass produced PV cells, with 18.5% efficiency when they are incorporated into a module. Laboratory calculations show that, although 20% has long been regarded as the practical limit for silicon solar cells, the fundamental efficiency limit was close to 28%, with 25% being a reasonable experimental target. Gallium arsenide cells are up to 18% efficient but are extremely expensive and the production processes are not at all environmentally friendly, so they haven't caught on. The GM Sunraycer used mostly gallium arsenide cells in 1987 b~t, even though they gave it enough advantage to win, only the Sunraycer clone, Solar Flair from California State Polytechnic University, Pomona, used them in 1990. However, it seems their cells were seconds and they gained little advantage, coming 11th with an average 44.4km/h, compared with the Sunraycer's average of 66.9km/h in 1987. The Spirit of Biel team used the "Green" laser grooved, silicon PV cells with an innovative overlapping or 'shingle' arrangement to take advantage of the 'buried' contacts in the top and bottom of the cells. This gave them a packing density of 97.5% for their panel array, with a resultant increased output for the allowable area (see box for race rules). Since the 1990 WSC, Dr Green's team has announced that they have achieved a further substantial increase in efficiency with their laser grooved (see Fig.1) buried contact, silicon photovoltaic cells. The laser grooves, in two directions at right angles to each other, form tiny inverted pyramids that 'trap ' the light, reflecting it internally up to 50 times. Amorphous silicon cells Tipped by its developers, Semiconductor Energy Laboratories (SEL), to be the first PV cells to enter large scale mass production, amorphous silicon cells were used on the very elegant looking Mazda Southern Cross in the 1990 WSC. Because amorphous cells are not as efficient as monocrystalline cells or laser grooved cells, the Southern Cross took 97.5 hours to make 28th. However, they are much cheaper to produce and, because of their thin film construction, they are very flexible , making them easier both economically and from a design point of view to use for solar vehicles. Sanyo has developed amorphous silicon solar cells which need an amorphous silicon layer only five microns thick to produce PV activity, about 1/60oth that for single crystal silicon. Using amorphous silicon, The sleek Hoxan "Phoebus III" looked as though it should have done better than fourth. It covered the route in 57 hours & 21 minutes. Below: "Phoebus III" spread out to catch the last few rays of sunlight just north of Tennant Creek in the Northern Territory. Sanyo has also developed a seethrough PV cloth which has already been used to power the Sun Seeker light aircraft on its attempt to fly across America in July 1990. The aircraft remained airborne for 7 hours and 35 minutes and covered a world record breaking distance of 330km. From a practical point of view, amorphous solar cells are likely to see widespread use as battery boosters on electric vehicles, electric sunroofs and so on, before the more efficient but more expensive cells. The average of the energy generation potential from the solar arrays of all the vehicles was around 1.3kW. Lead-acid or silver-zinc? Around half the cars in the 1990 WSC used lead-acid batteries and most of the other half used silverzinc, the rest using nickel-zinc or none at all. Battery capacities varied considerably, with the silver-zinc batteries having approximately twice the capacity of the lead-acid types. The first five cars home used sil- ver-zinc batteries; the sixth, Australian Energy Research Laboratory's (AERL) secondhand Ford from 1987, used lead-acid cells. Apart from being the first Australian built car to finish, it completed the journey in a full day and one hour less than it took in 1987, when it used silver-zinc cells. Perhaps even more significant is that this car, with its $25,000 racing budget, finished only three and a half hours behind the million dollar second place Honda entry, after 60 hours of racing! Despite the success of the silverzinc cells, they are not yet a practical option for urban vehicles because they can easily be damaged if discharged completely. They have a very high initial cost, typically about $12,000 for competing cars, and they can only be recharged about 15 times before they lose much of their capacity. Compare this with the relatively low replacement cost of lead-acid batteries, plus an expected 300 or more charge/discharge cycles, and it is obvious which is the more practical option. The Solar Star hasn't even had the battery ·caps off in over 5000km of running, including the WSC and the successful world speed record attempt. Besides , as can be seen from the results of both the AERL car and the Solar Star, they are not so far behind in long range performance and well ahead in outright speed. Only two cars used nickel-zinc batteries. The first of these to finish, Kyocera Corporation's Blue Eagle, was the 14th car to cross the line, after 72.4 hours running. This car also used a solar concentrator and a Stirling engine to add to its solar power but unfortunately the engine as well as some of their batteries failed, so its potential wasn't really tested. Although they both used silver-zinc batteries, one of the main factors credited for Spirit of Biel II's win over the Honda car was its superior battery capacity of 86, 25Ah cells connected to give 129V, as opposed to Honda's 68, 20Ah cells connected to give 102V. Two cars used no batteries at all. The first of these to finish was Sofix of Japan which, although the heaviest vehicle in the event at 290kg, finished in 21st position after 96.8 hours running, most of it under overcast conditions. The other 'solar only car' was enAPRIL 1991 9 Dripstone High School's "Aquila" braves yet another big truck on the dusty bitumen of the Stuart Highway. Note how its panels are tilted to capture the morning sun. tered by the Solar Research Association (Australia) and claimed 2 7th position after running 97.3 hours. Peak power trackers Eight of the first 11 vehicles in the 1990 WSC ran Australian Energy Research Laboratory (AERL) miniature, customised 'race trim' Maximizers, with 15 teams in total using more than 50 Maximizers between them. Ironically, although they had purchased Maximizers, the secondplaced Honda entry didn't use them as the team misunderstood the importance of peak power trackers (PPT). Spirit of Biel II used seven of their own design PPTs, each handling 220W and weighing only 0.4kg. They claimed an efficiency of up to 98.6% at 30°C. Just how important are they? PPTs are to solar photovoltaics (PV) what an automatic gearbox is to a car. Both link the power source to the load and permit the most efficient operation by exactly matching the power source at all times to the ever changing requirements of the load. The gearbox does this mechanically, while PPTs like the Maximizer use a DC-DC step-down converter to automatically maximize the electrical power delivered from the PV panels to the battery. Generally speaking, each section of the solar panels that can expect to have the same amount of solar radiation reaching it at any one time should have its own peak power tracker. This reduces the need for 'averaging' between cells that are in shadow and others that are in bright sunlight. AERL claim that their Maximizer PPT can easily produce 25% higher battery charging rates than would be achieved without the Maximizer under the same conditions (ie, 25% better on the day). Obviously, when such an effort is being put into increasing the efficiency of solar cells by a few percent, being able to achieve up to 25% more by using PPTs is more practical and cost effective. Pride of Maryland, which placed third in the US Sunrayce and was one of the GM sponsored cars, used 10 NASA designed PPTs. Because these relied on manual adjustments to find the maximum power point for each array, they proved unsatisfactory. Desert Rose, run by the Northern Territory University, used 26 PPTs they designed themselves. These took a 3ms sample of the open circuit voltage every two seconds and used an open loop algorithm to establish the optimum parameters through a 65kHz FET chopper. Because a relatively low battery voltage (42V) was used, three DC-DC converters were used to step the voltage up to 350V for the motor. Using five FETs on each side of a push-pull transformer, together with transformer current sensing, the converters returned an amazing 97.8% efficiency. Getting the power down p-silicon rear contact oxide Fig.1: diagram of the 23% efficient, laser grooved, silicon solar cell recently developed by the University ofNSW and used on the "Spirit of Biel II", winner of the 1990 World Solar Challenge. 10 SILICON CHIP The Spirit of Biel II was able to convert an astonishing 86% of the solar energy collected to mechanical energy at the drive wheel. Compare that with the efficiency of converting the energy contained in petroleum fuel to mechanical energy! Several of the cars used the powerful, lightweight UNIQ motors (see SILICON CHIP, January 1991). The overwhelming majority of competitors used DC motors, many of them brushless DC permanent magnet motors, including the winning Spirit ofBiel II, which used a specially made "Grundfos" clearly showing the 'table top' construction of its solar panel. The Rules "Grundfos" clearly showing what a willy willy can do to a car with 'table-top' construction of its solar panels. motor with a nominal power of 1.lkW and a maximum power of 5kW. Pride of Maryland was able to idle along at about one eighth power most of the time and take the hills in its stride with its 14.9kW UNIQ motor, unlike Konaweena High School from Hawaii, whose UNIQ motor had so much torque that it ripped itself right out of its mountings! But then, their Kalaikaka had other problems such as their new Trogan Pacer batteries being shipped to Auckland instead of Darwin so they only had old lead-acid cells for the WSC, a blown up DC-DC converter, many flat tyres and so on. But they finished 18th after a run of 96.2 hours. Transmission chains obviously play a large part in getting the 'power to the ground' and geared belts and chains and sprockets were the most popular way of transmitting the power from the motors to the wheels and so to the road - usually via small bicycle type wheels. Tests and experience have shown that the narrow, high pressure tyres reduce rolling resistance to a fraction of the wider softer tyres. In many cases, the wheels are streamlined with plastic discs or wheel spats. The successful Solar Star uses aluminium disc wheels and tyre pressures of 80kpa to achieve a rolling resistance of only 0.004. Body design As well as low rolling resistance, lightweight aerodynamically slippery bodies are obviously of paramount importance. In many cases, to achieve the light weight, strength and durability were Essentially the vehicle has to fit into a box six metres long, two metres wide and one metre high. Competitors can do virtu ally anything they like in that box, as long as it's Sun-powered. Sunlight is the only source of power to be used for the racers. More formally, the maximum vehicle dimensions are 6m long x 2m wide x 1.6m high. The solar array may not exceed 4m long x 2m wide x 1.6m high . As many as four people are allowed to share the driving, each one ballasted to 85kg . If you happen to weigh more than 85kg, plan ahead to lose weight, have an operation or drive with a weight penalty. A handbrake, friction brakes, brake lights, turn indicators, rear vision viewers and seat belt/s are required on all cars. Cars may only race from 8:00am to 5:00pm each day and must stop wherever they happen to be at 5:00pm. Charging of the batteries, using only the car's solar panels, is allowed from 6:00am to 8:00am and from 5:00pm to 7:00pm - after which, the car must be put into a lightproof container. Vehicle maintenance or repairs may only be carried out between 6:00am and 7:00pm. Defective batteries may be replaced but only with a costly time penalty. After scrutineering, each car will be accompanied by an official observer to ensure that all the rules are complied with. APRIL 1991 11 World Solar Challenge - Advancing Electric Vehicles The instrument panel of the "Solar Star" showing the aircraft type steering yoke, computer readout and neat array of switches. The keyboard port is on the bottom right of the panel and the slot for the magnetic memory card on the bottom left. During the WSC, the drivers were able to play computer games to alleviate the boredom of travelling at a relatively low speed along a fairly straight, flat road for hours at a time. sacrificed, which.meant that time was lost repairing cracks or even complete structural failures. Most vehicles used lightweight tubing , a la Sunraycer, with a Nomex Kevlar sandwich body to carry the solar panels. To keep the profile down to a minimum, and consequently the coefficient of drag (Cd), the vehicle was designed to be driven from almost the prone position. Driver comfort is also not unimportant on such a long journey with fairly high pressure tyres. A Cd of 0.12 was claimed by several cars and the Spirit of Biel II achieved 0.13 , all less than half the Cd for the average family car. was 2000km along the track when a willy willy tore the complete panel off, lifting the car, turning it over and dumping it upside down in the process. The driver was unhurt but the panel landed 50 metres away and suddenly the race was over for the Solvogn team from Denmark. Dripstone High School had to restrict the speed of their Aquila if there was any crosswind. Alarus, driven by Dimitri Lajovic, was tipped over by crosswinds several times and Detlef Schmitz was sitting on the side of the road having a cup of tea when a willy willy destroyed his 5-wheeler completely. Stability What was gained One of the most publicised aspects of the WSC is the stability test, in which each vehicle has to drive at full speed past a 58 wheel, 3-trailer road train travelling at 80km/h in the opposite direction. All of the vehicles that competed passed this test, but not all passed the willy willy test further down the track. Grundfos Pumps, one of the several "table top" models with solar cells in a flat panel mounted on struts, For the 3007km journey, Spirit of Biel II consumed the equivalent of 12 SILICON CHIP 50kWh of energy which corresponds to 0.165 litres of petrol per 100 kilometres or 4. 95 litres for the whole journey! That's the equivalent of 2727mpg! Old problems were redefined in new ways and new problems manifested themselves. Overall there was considerable improvement in almost every area of technology associated with the vehicles, their support crews and their campaigns. More cars and people participated, more was achieved for less cost, and several million more people in the world learnt about solar cars and the potential of solar energy through the tremendous amount of publicity the event gained world wide. Personally, I think that, in the long term, the Aquila team from Dripstone Junior High School in Darwin have cause to be more satisfied with their effort than any other team. They set out to demonstrate that schooling should not be restricted to the class room and that educational opportunities extend beyond the school - and they succeeded admirably. Their 28-member team took part in a world class event at the cutting edge of the most important technology today and gained a credible 19th place. This sort of participation can be an inspiration for the rest of their lives. They will never forget it. Neither will the rest of their school, their families or their peers around the world, to whom they have shown the way. SC Changing the right hand rear disc wheel on the "Solar Star". The motor unit and ridged aluminium brake drum can be seen here. MAMMOTH KITS REMOTE ALERT/ DOORBELL BOOKSHELF SPEAKER ENCLOSURES A remote chime that's ideal for invalids or simply use it as a remote doorbell. With the remote transmitter there is no need for unsightly wiring for temporary or mobile use. Push a button and the alert sounds a pleasant two tone chime. When used as a doorbell it eliminates the need for unsightly wiring. Quality speaker kit to match Magnavox 15cm driver and 3AC tweeter. Kit includes cabinets, sleeves, baffles and all components for crossovers. Cat K-2730 6MV Woofer Speaker K-3999 (originally $29.95) 3AC Tweeter Speaker K-3998 (originally $6.95) Cat K-4000 Originally $129! s39e5 QQ Originally $59.95! KITS Walkabout Wadio Motion Detector Tilt Alarm Battery Power Supply RF Probe (suits Bench Amp) Ni-Cad Fast Charger Sprinkler Timer Low Cost Amplifier (s/form) 120W-150W Spkr Protector Brake Lamp Monitor Vehicle Exhaust Monitor 30W Stereo Amplifier (s/form) UHF GasFet Preamp RF Attenuator 80m Low Power Transmitter 80m VFO to suit K-6326 80m Direct Converter Morse RTTY Decoder 3 Band Short Wave Radio CAT NO. PARTS VALUE K-2720 K-2721 K-3248 K-3460 K-3470 K-3476 K-3588 K-4001 K-4008 K-4500 K-4610 K-5100 K-6309 K-6323 K-6326 K-6327 K-6328 K-6339 K-6355 $30 $35 $7 $60 $10 $100 $100 $180 $40 $35 $85 $130 $80 $80 $40 $30 $50 $170 $80 S986 55P S,4996 '2P 5 1195 100 WATT HF LINEAR AMPLIFIER PRICE s1gas s,495 ssr s,495 s5r s5r se '2P s1gas se sgg $99/pair Over $400 worth of parts! Install this wide band HF amplifier between your rig and antenna. It will boost your power output by 10 to 14dB .. . that's up to 150W PEP! (-3dB at 28MHz) Use it with any HF gear between 1.8 and 30MHz with up to 15 watts output. Includes carrier operated Rx/ Tx switching and a switchable low-pass filter capable of delivering 30dB harmonic rejection. Cat K-6331 QQQ '199 1996 53995 57996 s,4195 5 B1103/PB DIGITAL SINE/SQUARE WAVE GENERATOR This new Digital Sine & Square Wave Generator uses high speed CMOS ICs and a digital filter to produce waveforms over a frequency range of 0.1Hz to 500kHz. It also features a 4-digit frequency readout, an output level control, & course/fine frequency adjustment. Supplied with pre-punched front panel, case, & all components. Cat K-7350 A kit from Dick Smith Electronics will never let you down. All our kits are covered by a money back guarantee* in case it all looks too difficult. Expert advice is available over the phone. We can even service your finished kit for a small fee! * Kits may be returned if inner components bags are unopened and packaging is in its original condition ~ !J:f,j~ -== ~!f)Jj· July '90 5 149 ALARM SIREN MODULE Need an extra module for your home or car alarm? This is the perfect addition. Some car and house alarms can be disabled simply by cutting the power off. But not this one! It monitors its supply voltage for fluctuations. If the external supply is cut, or varies excessively, the siren is triggered. You can add this module to your existing system or use it as a stand alone unit. ♦ lf>-1(1~ 1-AB~= (Horn speaker not supplied) Coming Soon! AM STEREO TUNER ..--7.""";=c=-=~--..::---, Cat K-6250 <at>oct'90 s1215 Sophisticated Security For Your Home Alann! ALARM PHONE DIALLER Our 'smartest' alarm ever! It features an intelligent warning lamp to indicates various alarm modes and four inputs which are sensitive to both rises and falls in voltage. Entry and exit delays give you time to arm or disarm the alarm, with a single button to arm and ignition key to disarm. A two second pause in accessory position is needed to disarm. This should foil would be thieves tampering with your car's ignition. Includes PCB all components, illuminated arm switch, case and nylon plugs and sockets. Cat K-4300 <at> Feb'91 s49ss An amazing device that can be fitted to almost any alarm system. If your alarm is triggered, the Phone Dialler calls the number you have pr09rammed into it and emits a distinctive tone. The kit even includes a pushbutton telephone and Plug-pack power supply. Cat K-6300 -:llf/'1'i,~ rzi LLJ Sept '89 Kits marked with this symbol involve mains power wiring . Take extreme care when working with this equipment. Degree Of Simplicity 2M VHF FM TRANSCEIVER FeabnS like- Full PLL frequency synthesis 24 memory channels with repeater shifts 25W or SW switchable output SkHz or 25kHz tuning steps Microprocessor control system Excessive SWR safety shut-down circuitry 0.15uV sensitivity at 12dB SINAB 30kHz selectivity at -60dB -60dB image rejection At this price you can afford to take the challenge! Kit includes all components, hardware, heatsink and a pre-punched silk screened front panel. Microphone is not supplied. YAESU D-2110 or D-2105 are recommended. Q QQ QQQ Simple Intermediate Detailed QQQ This outstanding high performance FM transceiver can be used as either a mobile or base station on the 144-148MHz amateur band. It must be one of the easiest transceivers of its kind to build yet it comes loaded with advanced features • • • • • • • • • QQ Cat K-6400 Onlys <at> Jan, Feb, M ' HALF PRICE COMPONENT SPECIALS -=====E1-~~-··57J.== Buy in bulk and save/ 50V CERAMIC CAPACITORS HIGH VOLTAGE CERAMICS 3kV CAT NO. R-2215 R-2217 R-2219 R-2221 R-2223 R-2225 R-2227 R-2229 R-2231 R-2233 R-2235 R-2237 R-2239 R-2241 R-2243 R-2245 R-2247 R-2249 R-2251 R-2253 R-2257 R-2259 R-2285 R-2287 R-2289 R-2291 R-2293 R-2295 R-2296 R-2297 R-2299 R-2301 R-2303 R-2305 R-2307 R~2309 R-2311 R-2313 R-2315 R-2317 R-2319 R-2321 R-2323 R-2325 R-2327 CAT NO. pF PRICE 10 UP PRICE R-2375 R-2376 R-2378 R-2380 R-2381 R-2382 R-2383 R-2384 R-2386 R-2387 R-2388 R-2389 R-2390 R-2392 R-2393 R-2394 R-2395 R-2396 R-2398 R-2400 100 120 150 180 220 270 320 390 470 560 680 820 1000 2200 3300 4700 5600 6800 8200 10000 $1.55 $1.55 $1.55 $1.55 $1.55 $1.55 $1.55 $1.75 $1.75 $1.85 $1.85 $1.95 $1.95 $1.65 $1.85 $2.05 $2.25 $2.45 $2.65 $2.85 $0.75 $0.75 $0.75 $0.75 $0.75 $0.75 $0.75 $0.85 $0.85 $0.90 $0.90 $0.95 $0.95 $0.80 $0.90 $1.00 $1.10 $1.20 $1.30 $1.40 pF 1 1.5 2.2 2.7 3.3 3.9 4. 7 5.6 6.8 8.2 10 12 15 18 22 27 33 39 47 56 68 82 100 120 150 180 220 270 330 390 470 560 680 820 1000 2200 3300 4700 5600 6800 8200 0.01uF 0.022uF 0.033uF 0.047uF PRICE 20c 20c 20c 20c 20C 20C 20C 20C 20c 20C 20c 20C 20c 20c 20C 20C 20c 20c 20C 20c 20c 20c 20c 20c 20C 20c 20c 20c 20c 20c 20c 20C 20C 20c 20C 20c 20c 20c 20c 20c 20C 20c 20C 20C 20c ONLY 10~ EACH FOR 10 OR MORE DICateiMITH PHONES •----.~.-..-~"T~....-,•--_...:Jllli_..,...-._.....-,-.,-~,~-,~,-,·-,·-,~..-,(..-t:II-_ ~1~..!:"A•~ ~ ~-7 ?! ~ __ ~ _ _ SECURITY AUDIO -~•ef-....-,...~--~-.r-~•~-rl-ri"Tj"""~-.•.,,...., ......, ...\l-i.,........(.-,r-~....,,..t"I._ COMPUTERS 5W WIRE WOUND RESISTORS POLYSWITCH PROTECTORS mA PRICE 10 UP PRICE 0.5 0.7 0.9 1.15 1.35 1.85 2.45 3.05 3.9 $8.95 $8.95 $9.95 $9.95 $10.95 $10.95 $11.95 $12.95 $14.95 $4.45 $4.45 $4.45 $4.45 $5.45 $5.45 $5.45 $6.45 $7.45 Cat No. R-1600 R-1603 R-1601 R-1602 R-1604 R-1606 R-1610 R-1614 R-1618 R-1620 R-1622 R-1624 R-1626 R-1628 R-1630 R-1632 R-1634 R-1636 R-1638 R-1640 R-1642 R-1644 R-1646 R-1648 R-1650 R-1652 R-1654 R-1656 R-1658 R-1660 R-1662 R-1664 R-1666 R-1668 R-1670 R-1672 R-1674 R-1676 R-1678 R-1680 R-1682 R-1684 R-1686 R-1688 R-1689 R-1708 Ohms 0.1 0.22 0.47 1 1.2 1.5 2.2 3.3 4.7 5.6 6.8 8.2 10 12 15 18 22 27 33 39 47 56 68 82 100 120 150 180 220 270 330 390 470 560 680 820 1k 1.2k 1.5k 1.8k 2.2k 2.7k 3.3k 3.9k 4. 7k 8.2k Price 65C 65c 65c 65c 65C 65c 65C 65c 65C 65C 65C 65C 65C 65C 65c 65C 65C 65c 65C 65C 65C 65C 65C 65C 65c 65C 65c 65C 65c 65c 65C 65C 65C 65c 65C 65C 65c 65C 65C 65C 65c 65C 65C 65C 65C 65c ONLY 30~ EACH FOR 10 OR MORE DS XPRESS PHONE & MAILORDER SERVICE Outside Sydney (FREE Call) 008 22 6610 Sydney And Enquiries - 888 2105 FAX: (02) 805 1986 or write to DS XPRESS, PO BOX 321 N/RYDE NSW 2113 All Major Credit Cards Accepted. O/Nite Courier Available. 24 HOUR DESPATCH OF ALL ORDERS 81103/BL NSW • Albury 21 8399 • Bankstown Square 707 4888 • Blacktown 671 7722 • Brookvale 905 0441 • Bondi 387 1444 • Campbelltown 27 2199 • Chatswood Chase 411 1955 • Chullora 642 8922 • Gore Hill 439 5311 • Gosford 25 0235 • Hornsby 477 6633 • Hurstville 580 8622 • Kotara 56 2092 • Liverpool 600 9888 • Maitland 33 7866 • Miranda 525 2722 • Newcastle 611896 • North Ryde 878 3855 • Parramatta 689 2188 • Penrith 32 3400 • Railway Square211 3777• Sydney City2679111 • Tamworth 661711 • Wollongong 283800ACT• Belconnen (06) 253 1785 • Fyshwick 80 4944 VIC • Ballarat 31 5433 • Bendigo 43 0388 • Box Hill 890 0699 • Coburg 383 4455 • Dandenong 794 9377 • East Brighton 592 2366 • Essendon 379 7444 • Footscray 689 2055 • Frankston 783 9144 • Geelong 232 711 • Melbourne City 399 Elizabeth St 326 6088 & 246 Bourke St 639 0396 • Richmond 428 1614 • Ringwood 879 5338 • Springvale 547 0522 QLD • Brisbane City 229 9377 •Buranda 391 6233 • Cairns 311 515 • Chermside 359 6255 • Redbank 288 5599 • Rockhampton 27 9644 • Southport 32 9033 • Toowoomba 38 4300 • Townsville 72 5722 • Underwood 341 0844 • SA • Adelaide City 223 4122 • Beverley 347 1900 • Elizabeth 255 6099 • Enfield 260 6088 • St. Marys 277 8977 WA• Cannington 451 8666 ~:~~~~ ~~k9::~; 'frth City 481 3261 • Midland 250 1460 • North bridge 328 6944 TAS • Hobart 31 0800 7 YOUR EIGHT SPECIALTY STORES IN ONE A trip to the hardware store for that latch set, window lock or a replacement part for your plumbing system should be a simple matter - or is it? Often, it isn't. But all that could change in the future. By BERNARD MALONE* A new way to store images OU WALK into the hardware shop with the confident air of someone who knows exactly what they want. Mere minutes later you have acquired a feeling of gross inadequacy after a sales assistant has destroyed your confidence by asking if the part is a left or right handed fitting? Do you want brass or mild steel? Do you want a flush or mortise fitting, or is it a 50mm or 85mm backset with recessed rebate in a bright annealed finish. We are all familiar with trying desperately to draw word pictures of what we need, only to leave the shop with a sense of frustration after our attempt at buying that special widget turns sour. All this may change soon as business recognises that today's low cost image database technology can be applied very easily to helping people make buying decisions. Image database technology? Think of it as video images and text stored in a computer for easy access by customers and sales staff. Such technology is now well within the reach of retail businesses. By using today's standard hardware with locally developed software, a typical trip to virtually any retail outlet would change dramatically. An image database * Bernard Malone is Assistant National Marketing Manager, Still Video Division, Canon Australia Pty Ltd. 16 SILICON CHIP Now when you go to the hardware store, you march up to a screen and let your fingers do the talking. The system will very quickly let you eliminate items that don't fit your need and come to the final choice. It may be a component for your new irrigation system, or a hard-to-describe latch set for that door you are just about to hang. Having established exactly what you need and having found that the item is indeed in stock, you could be on your way home in minutes. You would be happy and the retailer would have made a sale to a satisfied customer. Hang on - what retail establishment has the time, inclination and resources to do this? Isn't this a bit of crystal ball gazing? Definitely not. Such a system is currently available and at a relatively low cost. How does such a system work? It uses existing computer hardware, Canon's ION Still Video camera is an interesting marriage of CCD imager and floppy disc technology. The 50mm floppy stores the analog signals for 50 still pictures. Viewfinder Unit CCD Image Sensor Shutter Unit Display Panel Lens Battery Pack White Balance Sensor Disk Drive Unit Signal Processing Board Flash Signals from the ION camera can be viewed on a conventional PAL monitor and you can step through them frame by frame. Image quality is about the same as "still" frames from a typical HQ VHS video recorder. new video hardware , and software written especially for this application. Image databases include images and text together on a screen, where a few simple keyword prompts will search the images in the database. The search brings up a montage or individual images on screen that fit your "idea" of what you want to buy or examine. Image databases are well suited to establishments which have a very large range of high value products. Jewellery stores are a typical example. Traditionally, sales staff have to remove trays of small valuable items for a customer's inspection. A simple image database would enable the assistant or th e customer to key in a few simple "hints" of what they are look- ing for and a series of products that most closely fit the idea can be displayed. Having reduced the alternatives, it then becomes a much more practical matter for the shop assistant to present these for a final decision by th e customer. So how does the shop capture and handle these images? How quickly does the system respond to enquiry and how specific do the enquiry criteria need to be? The key to image capture and handling is Canon's new range of Still Video equipment, which overcomes the cost and speed problems associated with scanning images, and a newly developed image database software package. Images are taken directly into the system's software by using either the Canon ION Still Video camera or the Canon RE-552 Video Visualizer. Canon's still video camera The ION camera is quite small and light - it fits in the palm of your hand and will photograph 50 images on a 50mm floppy disc. The camera is APRIL 1991 17 in playback mode, it produces conventional PAL composite video signals. Any of the 50 images on a floppy disc may be displayed. Furthermore, any image may be erased and replaced by taking a new picture. So that is one way of acquiring video images for a database. The other way is with the Video Visualizer. Canon's Video Visualizer The complete Canon setup for image processing and storage in a database includes the ION camera, the Video Visualizer (which includes a built-in colour camera with a zoom lens) and an AT or 386 computer with a 40Mb hard disc and a VGA screen. ideal for capturing large images such as ladders, outdoor furniture, power tools or garden implements. However, it can be just as effective for photographing even small items down to 30cm shooting distance in macro mode. The Canon ION camera has a fixed focus 11mm fZ.8 lens which is equivalent to a 60mm lens in a 35mm camera. It focuses normally to one metre and down to 30cm when in the macro mode. There is a built-in flash with a choice of shooting modes. When set to "auto" , the flash will fire when the camera senses low light conditions. In the "on" mode, the flash will fire on every shot. A liquid crystal display (LCD) indicates the shooting mode, disc condition, track number, battery condition and self-timer. The camera is powered by a long-life rechargeable battery good for shooting 700 images without flash. On battery power, the camera will play back for 10 minutes. The battery charger supplied with the ION camera doubles as an AC adaptor for mains-powered playback. Record, playback and erase facilities are all contained in the small, lightweight unit. Exposure is adjusted automatically and it has selectable backlight exposure compensation. The ION 's CCD imager converts the lens image into video signals which are recorded onto the 50mm floppy disc in analog format. The CCD has 786 pixels horizontally, enhanced by an on-chip colour strip filter for accurate colour reproduction. High picture quality is achievable because the camera uses "high One of the benefits of the Still Video camera is that if band" video circuitry. some of the shots are unsatisfactory, you can just step through to the wanted pictures and shoot them again. When the camera is 18 SILICON CHIP The RE-552 Video Visualizer is a portable image input device which includes a built-in colour video camera mounted above a document table which is illuminated by fluorescent side lights. The camera has an 8x zoom lens and can be positioned for close-ups. Focus, exposure and white balance are all adjusted automatically. The Visualizer lets you transfer virtually any image into your database from photographs, negatives, "lifting" whole or part images from magazines, drawings, transparencies and even 3dimensional objects. The benefit of the Visualizer is that images of large items can be easily obtained from catalogs and illustrations, while a number of smaller items can be grouped in the one image. The Visualizer's camera: has a 420,000 pixel CCD sensor with horizontal resolution of 300 TV lines. The main operating controls are located along the front panel of the document table with LED indicators above each function control. There is a negative/ positive conversion button, a control for auto white balance, and a manual white balance control. You then have an exposure compensation control and manual and auto zoom controls. When the "normal" camera position is selected, you can focus on objects or document surfaces ranging from 335 x 250mm down to 43.3 x 32.4mm. If you want to capture smaller objects, down to around 33 x 25mm, the "close up" position can be selected. Three dimensional objects present no problem, as the depth of field of the camera in the "normal" position will enable good focus on objects about 50mm deep. The depth of field diminishes in the close up position. Database software The database software has been designed by OSR Digital Video Systems (well known for their Super Comms communications software) Specifications The ION is an electronic lens shutter camera which uses a 0.5-inch CCD with 786 pixels horizontally, with a total of 230,000 pixels. The video signal is PAL colour format which is recorded on a Still Video floppy disc. The camera's lens is a built-in fixed-focus type with a macro mechanism for extreme close-ups at 30cm. Viewfinder: Heal image secondary imaging finder Magnification: 0.55x Finder Coverage: 84% Dioptric Adjustment: -4 diopter to +2 diopter Light Metering: Feedback AE with external photometric sensor and CCD signal Exposure Mode: Program AE (1/30 sec, f2.8 to 1/500 sec, f22) Flash Sync Speed: 1/125 sec White Balance: Automatic tracking system Shooting Mode: Single image and continuous (3 images/sec) shooting Self-Timer: 10 second delay Video Output: 1Vp-p, 75Q unbalanced via 2.5mm mini-jack. Horizontal Resolution: Recording/playback - 300 TV lines (min.); playback - 350 lines (min.) Playback Function: Playback single image or continuous images (approx. 4 images/sec) by means of Forward or Reverse buttons. Playback automatically cancelled when single-image display exceeds 2 minutes (when using battery pack) or 15 minutes (when using battery charger) Erasure Function: Single image erasure. specifically for the storage and display of images which can be corn~ bined with text and field information. This allows the user to define all database categories from flat field to multi-database search fields. If a customer in a hardware store was searching for a door latch set, for example, the user may establish a prime search using the field criteria. For example, the input "door", "deadlock", "brass" and "stainless steel " would invoke the database to allow the searcher to see all products related to those criteria. Free form text and word search allows the user to search for items which may not be easily described by the criteria. Alternatively, the searcher can simply call up the database, for instance "door accessories", and browse through the multi-screen images and select the one he wants. "Multi-layering" is also possible if the user wants to be really clever. For example, the searcher calls up an image of a "door" and the image would have several "highlight" points such as "lock", "handle", etc. The searcher would simply click with the mouse on "lock" and the database would then display multi -screen images of the items in the "lock" database. Rolling slide show Another facility of the image database is its ability to be used by a retailer to create a rolling slide show of products while the system is not in use - great for in-store promotions. This can be done easily by designating a database called, "new products" which would immediately commence a continuous display of all new lines in the shop. Because video is being used, and because of the simplicity of using the Canon ION Still Video camera, setting up and editing of the image database is simple and time effective. Unlike scanning, the user can very quickly take a picture of the product and quickly enter it into the image database with a frame grabber, in- eluded in the database software package. Again , because video is being used, the amount of storage needed for an image is much less than with scanning. An average of 200Kb per file is all the space needed , so a simple complete system with 100Mb of hard disc storage will store up to 500 images/files , including text and field criteria. One of the major advantages of the OSR database is the ability to display and view images on any VGA screen without the need for a frame grabber. OSR's colour conversion techniques mean that when the image is captured by the Canon ION camera, it is automatically converted to a VGA format. This means the user can have multiaccess systems without the need to have a costly frame grabber in each computer. The speed at which images can be retrieved depends on the computer system being used. However, a typical enquiry from a basic system would take only a few seconds. This very sophisticated but simple to use image database technology, combined w ith Canon's new Still Video technology, will benefit a wide range of users. In fact, any organisation or individual that needs to identify, store and retrieve items from a high volume of images or objects will find the system extremely effective and surprisingly economical and easy to operate. Paying the piper A complete image database system comprising a Canon ION (Image Online Network) Still Video camera and database software and frame grabber board will cost around $4500 . If you don't already have a computer to run the system, you will need a standard AT or 386 computer with 640K of RAM, 40 megabytes of hard disc and a VGA screen. The cost of the Canon ION Still Video camera is $1300. The Video Visualizer is $5200, while the image database, including the frame grabber board, is $3200. In addition to viewing images on screen, by adding a computer printer to the system, the user gains the ability to produce hard copy of images or complete database files. This can be done in either colour or black and white, depending on the printer. SC APRIL 1991 19 . ~, ~~ '~ \ '. / ~<- ''. ' ' ·:- · ► / "...__. \ /1 ***GREAT RANGEi GREAT PRICEI*** ·,. - PRINTERS --- KEYBOARDS WITTY MOUSE EVER POPULAR , 1-9 C20094 , Size: 210 C20096 ' Size: 210 C20098 Size: 216 C20100 Size: 216 J $9.95 $9.50 11 .5 X 30m $9.95 $9.50 x 25.4 x 50m $19.95 $17.95 x 25.4 x 100m $9.95 $9.50 x 25.4 x 30m $11 .95 $11.50 x 24.4 x50m IBM 5537 Printe 9 pin 4 resident fonts C22170 ......... ... ........... .... $395 SAVE ON EPSON LX•400 9 pin .... .... ......... $299 L0•400 24 pirl .... ..... .. .. .. $499 . 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SPECIFIACTIONS: Resolution: 1024 x 768 Disply size: 245+/-Smm x 180+/-Smm Po-r supply: AC 115V/60 Hz or 230V/50 Hv Po-r Consumption : 85W max CTR: 14" 90 deltection. dark-tint, non - glare Input Signal: Red, green, blue and vertical/horizontal synchronization Input Level : Video analog 0.6vp-p Horizontal and vertical synchroization : positive or negative Character number: Approx 6000 Mlsconvergence: Centre: 0.3mm max, Corner: 0.5 mm max 1•9 8olN 10+ 31 /2"DD $19.95 $18.95 1-9eo,n 10+ 3 1/2"DD $39.95 $37.95 31 /2"HD $39.95 $37 .95 3 1/2"HD $69.95 $67.95 .....................................................•.$595 $8.95 5 1/4"DD $19.95 $18.95 51 /4"HD $19.95 $17.95 5 1/4"HD $39.95 $37.95 ****** UPGRADE NOW! ****** MOTHERBOARD PRICES CRASH! 51 /4"DD $9.95 DESCRIPTION DYSAN '/ •.~ S DIFFERENT COLOURS OR 1 SINGLE COLOUR! 10 D5/DD COMES WITH A FREE PLASTIC DISK BOXI 1•9 Bo1N 10+ 31 /2"DD $22.95 $21.95 1-9 eo,.. 10+ 31 /2"DD $29.95 $27.95 31 /2"HD $39.95 $37.95 31 /2"HD $49.95 $47.95 51 /4"DD $19.95 $18.95 51 /4"0D $19.95 $17.95 51 /4"HD $31.95 $29.95 51 /4"HD $29.95 $27.95 ROD IRVING ELECTRONICS - NEW PRICE 286-12 (16Mhz LANDMARK) 286-16 (21 Mhz LANDMARK) 286-16 (ALL IN ONE) 386SX-16 (21Mhz LANDMARK) 386SX-20 (27Mhz LANDMARK) 386-25 (32 Mhz LANDMARK) NO CACHE 386-25 (41 Mhz LANDMARK) 64K CACHE 386-33 (54 Mhz LANDMARK) 64K CACHE 486-25 (115Mhz LANDMARK) 64K CACH!;: 486-33 (157Mhz LANDMARK) 64K CACHE POSTAGE RATES $1 - $9 .99 ....... $3.00 $10 • $24.99 .... $3.50 $25 - $49.9 ..... $4.50 $50 . $99 .99 .... $6.00 $100 · $199.... $7.00 $200 - $500 ..... FREE $500 PLUS........ .. ................... FR EE The above postage rates are for bas ic postage up to 5Kg in we igh t & does not includ e insurance. Road freight bulky & fragile items will be ch arged at dttfere nt rates. $245 $295 $395 $695 $895 $1795 $1895 $1995 $3995 $5995 WAS $29'5" $49S' ~ $195 $995' U,495 ~ ~ $A,09'$' $:1,89'S All sa les tax exempt o rd ers & wholesa le inquiries to: RITRONICS WHOLESALE, 56 Ren ve r Rd, Clayton, Victoria. Ph: (03) 543 2166. Fax: (03) 543 2649. MAIL ORDER & CORRESPONDENCE P. O BOX 620, CLAYTON, VICTORIA.3168 Errors & omi ssi ons excepted. Pric es & specifica tions auject to change. ' IBM, PC , XT, AT, are reg istered tradema rk• of lntomaUonal Buainesa Machlne11. ~ ~ ',·, Build the SteamSound Simulator Had enough of that silly whine coming out of your HO-scale "38" loco? This steam sound simulator makes a realistic "chuffing" sound that keeps pace with the loco speed. T'S EARLY on a Saturday morning, about 7am, and you're relaxing in the leading carriage of a 5car set sitting on platform 1 at Central Railway Station. Looking around your compartment, you see a couple of black and white photos framed with scenes of the original Zig Zag railway near Lithgow. A "30 class" tank loco draws slowly away from platform 2 with the empty set from the overnight Southern Aurora that arrived half an hour ago. As it moves into the distance, its highpitched whistle signals that it has passed over the points, which now revert to platform 1. It's 7:04am and still no engine. The whole station is alive with the sounds of air compressors, people hurrying to their seats and a stationmaster mumbling something in the background. You shove your head out through I DARREN YATES 22 SILICON CHIP the window and in the distance see big plumes of steam gently drifting into the air. As it moves closer, you can just make out the rear of the tender and the numbers on the back, "3830". All attention is focused on platform 1 as the guard comes up and gets ready for the coupling. The carriage rocks violently back as the loco hits the end buffers. The guard points out to the driver in no uncertain fashion that he came in too fast. The driver just leans out the window and points to his watch. Three minutes to go. The brake lines and coupling hooked up, the familiar beat of the air compressor starts as the fireman stokes up the firebox with rich, black Muswellbrook coal. The guard, now leaning out of the guard's van, blows his whistle and holds out the green flag. The driver acknowledges with a long flowing blast of the whistle and eases the throttle open. The whole train groans as it moves slowly out of the station. The loco loses traction and slips, driving wheels spinning, but the driver recovers it and the Southern Highlands Express makes its way through the yard and onwards. This may be your memory of a steam loco or maybe you're one of the many who ventured to Hawkmount and Fassifern to watch the 60 class Garratts haul everything from coal to concrete. Whatever the case, you have to admit that a steam loco is infinitely more interesting than your average diesel - no bias intended, of course! Model railways Many of us have seen model railway layouts at exhibitions that depict some place about 30 years ago, with all the scenery carefully laid out to look as realistic as possible. Then you'll look down the track and see a steam loco pulling the "pick-up" goods train. Everything looks so realistic, until it passes you and you hear the whine of the electric motor inside the loco ... and the realism is lost. This little project fixes that prob- lem by producing a realistic chuffing sound through a small speaker which fits inside the guard's van or goods wagon directly behind the loco. It's specifically designed to go with our Railpower train controller published in the April and May 1988 issues of SILICON CHIP. However, it it possible to make it work with most other train controllers (we show you how later TO TRACK SAWTOOTH WAVEFORM GENERATOR BRIDGE RECTIFIER VOLTAGE REGULATOR +12V white noise source which is modulated by a sawtooth oscillator to produce the "chuffs". The speed (or frequency) of the sawtooth oscillator is made directly proprortional to the average DC voltage applied to the loco's motor (via the rails) so that the higher the DC voltage, the faster the rate of chuffing. The circuit is connected directly to LOW FREQUENCY AMPLIFIER POWER AMPLIFIER/ BUFFER DIODE MODULATOR WHITE NOISE SOURCE Fig.1: block diagram of the SteamSound Simulator. The speed information is derived from the track & this controls the frequency of a sawtooth oscillator. The sawtooth oscillator in turns controls a diode modulator, which then amplitude modulates a white noise source to produce the "chuffing " sound. in the article). It's also easy to build and uses no hard to get bits. In fact, you'll probably already have most of the parts in your junkbox. Block diagram Refer now to Fig.1 which shows the block diagram of the SteamSound Simulator. The circuit consists of a the track via a bridge rectifier which provides the power requirements fo r the circuit and also provides the throttle setting for the speed of the "chuffs". The bridge rectifi er allows the circuit to work correctly whether the loco is moving forwards or backwards. As mentioned earlier, the circuit was designed primarily for use with a pulse typ e train controller so before we go any further, let's go over the basic principles of PWM train control so that we understand what is meant by the terms "positive pulses" and "varying pulse width". All model locos use a simple method of transforming electricity to movement: you apply a voltage to the little motor and the loco moves. The higher the voltage, the faster it goes. OK, that should be obvious. However, at low voltages and due to dirt on the rails or the wheels, the motor will tend to not operate smoothly and may often stall on gradients and curves. By applying a pulsed DC voltage to the motor, we get much better speed regulation an d hence smooth running at low speeds. The loco will also start smoothly, without any of the jerkiness associated with conventional controllers. Fig. 2 shows how a PWM controller works. If narrow pulses are applied to the rails (as at the top of the diagram), then the motor averages these pulses out, so that in effect we have a small voltage across the motor. As the pulse width increases, the average voltage increases, which in turn, APRIL 1991 23 SLOW SPEEO PRODUCES NARROW PULSES MEOIUM SPEEO PRODUCES HALF-WIDTH PULSES j FAST SPEEO PRODUCES VERY WIDE POSITIVE PULSES Fig.2: how a PWM controller works. At low speed settings, only narrow pulses are applied to the rails to produce a low average voltage. At higher speed settings, the pulse width is increased to produce a higher average voltage across the motor. makes the loco speed up. Finally, if we have very wide positive pulses, the average voltage is very high and so the loco speeds around the track. · Now if we go back to the block diagram of Fig.1, the output of the bridge rectifier is fed to a voltage regulator which provides +12 volts DC to power the circuit. It is also sent to a voltage inverter stage and this controls the sawtooth oscillator. The reason for the inversion is to provide the correct control voltage for the oscillator so that we get the desired output; ie, to produce a low frequency output, we need a high voltage on the input and to produce a high freqeuncy output, we need a low voltage on the input. In effect, the sawtooth oscillator works the wrong way around, so we need to invert the incoming voltage to compensate. From the oscillator, we get a sawtooth output with a frequency proportional to the pulse width of the track voltage. To put it simply, the faster the train is going, the higher the frequency from the oscillator. This output is then fed to a diode modulator. To explain briefly, the conductivity of a diode changes depending on the voltage across it. This means that a diode with 0.6 volts across it will conduct more current than a diode with only 0.2 volts across it. In effect, we are using the diode as a voltage-controlled resistor but more about this later. Meanwhile, the white noise generator produces about 80mV of signal which makes up the steam and chuffing sound. By modulating or varying this signal, we can produce the effect of a train chuffing up a fairly steep hill or blasting along the flat. The white noise signal is modulated by feeding it to a low frequency amplifier and by using the diode modulator to vary the gain of this Our prototype SteamSound Simulator was built into a HO baggage van from Powerline Models Pty Ltd. Power for the circuit can be picked up by running leads through to the loco motor or by using a pick-up system from the rails. Using the SteamSound Simulator with the Simple Train Controller OK, can you use the SteamSound Simulator with the Simple Train Controller described in our November 1990 issue? The answer is yes but you do have to make a few minor modifications. You can use the same modifications to make the SteamSound Simulator work with just about any train controller. First, because of the way in which the Simple Train Controller works (ie, without a pulsed DC output), you will not be able to power the SteamSound Simulator directly from the rails. Instead, it will have to be powered from a separate DC sup- 24 SILICON CHIP ply. That in turn means that the project can no longer be mounted inside a carriage but you can mount it in a fixed position under the layout. If you're willing to accept that limitation, here are the modifications: (1 ). Disconnect the anode of diode D5 from the bridge rectifier and connect it instead to the external DC supply. This could be a 12V DC plugpack supply (which will give an output of about 16-1 ?V when lightly loaded}. Alternatively, you could use the supply rail to the train controller itself provided it is in the range 1518V DC; or you can use some other external DC supply up to about 25V. (2). Delete the 1.8kQ resistor connected to the bridge rectifier. (3). Change the 330kQ resistor on O2's base to 120kQ, the 27kQ resistor to 150kQ, and the 150kQ resistor to a 10kQ trimpot (tie the wiper to one of the outside pins). Note that you still must connect the SteamSound Simulator to the track via the bridge rectifier to derive the speed information. The trimpot is simply adjusted for best effect (ie, steam only when the throttle is closed, with the "chuffs" starting as the throttle is opened). 05 1N4004 100 . + l5VW+ WHITE NOISE SOURCE 14 .,. 0.1 .,. 1.2M FROM TRACK .001 1k. LOW FREQUENCY AMPLIFIER 150k 06 1N914 .0471 HIGH GAIN AMPLIFIER .,. 07 01+ 1N914 POWER AMPLIFIER/BUFFER DIODE MODULATOR +12V 27k +12V 0.11 15k B .,. ~ 1.8k E'Oc VIEWED FROM BELOW .,. +12V SAWTOOTH GENERATOR .,. STEAM SOUND SIMULATOR Fig.3: the final circuit is based mainly on an LM324 quad op amp IC. D1-D4 rectify the track voltage & this controls the frequency of the sawtooth generator based on Q2 & ICla. Ql is the white noise source. Its output is fed to IClb where it is amplitude modulated by diode modulator D7 to produce the "chuffing" sound. The output ofIClb is then amplified & fed to the loudspeaker. stage. This low-pass active filter stage amplifies the white noise and removes the high frequencies so that our "chuffs" have a bit more grunt to them. The output from the low frequency amplifier is then fed to a high gain amplifier. This stage amplifies the signal to a level suitable for driving the power amplifier and loudspeaker stages. Main circuit Take a look now at Fig.3 . It's based mainly on a single LM324 quad op amp to keep the parts count fairly low. Diodes Dl-D4 full wave rectify the PWM track voltage to produce the positive DC voltage pulses. This is then coupled via isolating diode D5 to a .7812 3-terminal regulator which produces a +12V DC rail. This rail directly provides power for the audio output transistors (Q3 & Q4) and is also decoupled using a 22Q resistor and 470µF capacitor to provide power for the small-signal circuitry (Ql, QZ and ICl). The positive-going pulses from the bridge rectifier are also fed to transistor QZ which forms the voltage inverter. The output signal appears at QZ's collector and is fed to a filter network consisting of a 6.8kQ resistor and l0µF capacitor. This filter network has two functions: first, it filters and averages the pulses to provide a steady DC voltage; and second, it forms part of the timing network for the sawtooth oscillator based on ICla. ICla is 1/4 of an LM324 quad op amp, connected as a standard Schmitt trigger squarewave oscillator but with a couple of changes. To start with, the oscillator uses the voltage derived from QZ to determine its frequency, so that it really acts as a voltage-controlled oscillator or VCO. Diode D6, connected ·in the negative feedback loop of the op amp, causes the output signal to be a series of short pulses. Let's now take a closer look at how The top trace of this CRO photograph shows the waveform across the speaker, while the bottom trace shows the waveform at the output of the sawtooth generator (pin 9 of ICla). CRO settings: upper trace 0.lV/ cm & 20ms/div; lower trace 0.5V/ cm & 20ms/div. APRIL 1991 25 15k 01-04;:: 0B ~ i'roh'<at>stl:k]~- +·•:. . i ,.1•1~©lT<at>; • !® I · • • 0 •••• 2.e., 27 A©-- 100uf A©---wi! _ Jf ~ + 22Q 01 330k 05 1a12 A, 'y ©- ©-----4 k©---- 22k -C::- l'G· o 0.1 ~ 330k 2!i ~ • 68k ..-<at> ,~ §Pi (!) :5 68k ~lOOk • 12 M . 10 [!]12;~r<at>O uF :g ~ ~ 1 . 03 + C)1oouF 04 • 25VW + ro: TRACK Fig.4: check each resistor with a multimeter before installing it on the PC board to make sure you have the correct value. The resistors are all mounted end-on to save space. The type numbers & pinouts for the transistors (Q1-Q4) can be gleaned from the main circuit diagram (Fig. 3). this oscillator works. Initially, the lOµF capacitor has no voltage across it and so the output of ICla (pin 8) is high. The capacitor now quickly charges via the 1.ZkQ resistor and D6 until it reaches the upper threshold level of the op amp (ie, the voltage on pin 10), as set by the two 68kQ and the 120kQ resistors. When it reaches this level, pin 8 switches low but this plays no part in discharging the lOµF capacitor because D6 is now reversed biased. Instead, the lOµF capacitor discharges via the 6.8kQ resistor to whatever voltage is at QZ 's collector. This voltage determines the time it takes for the capacitor to discharge to the lower threshold level, at which point pin 8 switches high again and the cycle repeats. The lower the voltage at QZ's collector, the faster the capacitor discharges and therefore the higher the CAPACITOR CODES 0 0 0 0 0 Value IEC Code EIA Code 0.1µF .068µF .047µF .001µF 100n 68n 47n 1n 104 683 473 102 output frequency. Since the voltage at QZ's collector is inversely proportional to the track pulse width, it follows that the oscillator speeds up as the train speed increases. The waveform across the lOµF capacitor is sawtooth shaped and this matches the waveform of a real "chuff" amazingly well. This signal is then fed to the anode of diode D7 via 150kQ and 330kQ resistors. The O. lµF capacitor at the junction of these two resistors is used to filter the PARTS LIST 1 PC board, code SC09104911, 108 x 28mm 1 32mm 8Q loudspeaker (IRH KSS-3108) Semiconductors 1 LM324 quad op amp (IC1) 1 7812 12V regulator 2 BC548 NPN transistors (01 ,02) 1 BC337 NPN transistor (03) 1 BC327 PNP transistor (04) 5 1N4004 rectifier diodes (D1-D5) 2 1N914 signal diodes (D6,D7) Capacitors 1 470µF 25VW electrolytic 2 100µF 25VW electrolytic 26 SILICON CHIP 2 10µF 16VW electrolytic 6 0.1 µF monolithic 1 .068µF monolithic 1 .047µF monolithic 1 .001 µF monolithic Resistors (0.25W, 5%) 1 1.2MQ 1 15kQ 1 560kQ 1 6.8kQ 2 330kQ 1 1.8kQ 2 150kQ 1 1.2kQ 1 120kQ 1 1kQ 3 100kQ 1 820Q 2 68kQ 1 22Q 2 27kQ 1 10Q 1 22kQ Miscellaneous Solder, hookup wire, etc. waveform and to prevent "clicks" in the output. Diode modulator D7 is the diode modulator stage depicted in Fig.1. Its cathode is connected to a voltage divider (27kQ & 15kQ) which sets the bias to about 4.3 volts. This provides us with a preset level and balance so that we don 't get too much steam and not enough chuff. The 0. lµF capacitor on D7 's cathode provides a low-impedance AC path to ground, so that we get maximum effect from the modulation. Whenever the DC level of the sawtooth waveform rises above 4.3 volts , the diode begins to turn on and this decreases its AC impedance. The .068µF capacitor thus sees a progressively lower impedance to ground as the voltage across D7 increases. Because IClb is connected as a noninverting amplifier, these impedance variations directly control its gain. If . the impedance goes down, the gain goes up. Conversely, if the impedance goes up, the gain goes down. Thus, D7 modulates the gain of IC7b to provide the "chuffing" effect. White noise source Transistor Ql is used as the white noise source. This transistor is connected as a reverse biased diode (ie, the base-emitter junction is reversed biased) and the resulting noise is coupled via a O. lµF capacitor to pin 12 of IClb. IClb functions as a noninverting amplifier with modulated gain, as detailed above. The .OOlµF capacitor in the feedback loop rolls off the upper frequency response of this stage. The modulated output from IClb appears at pin 14 and is direct coupled to non-inverting amplifier stage IClc. From here, the signal is passed to pin 3 of ICld which, together with transistors Q3 and Q4 , forms the output stage. Q3 and Q4 buffer the output of the op amp to provide current gain and are connected inside the feedback loop to minimise distortion. The lOQ resistor and the 0. lµF capacitor at the output form a Zobel network, which stops the circuit from oscillating. The output signal is coupled to the loudspeaker via a lOµF capacitor. A value of lOµF might seem a bit puny for a normal amplifier but since it is only handling modulated white noise there is very little low frequency information and so a small capacitor can be used. For the same reason (ie , no low frequencies), a small speaker can be used and still provide quite a surprising level of steam sound output. Construction All components except for the loudspeaker are mounted on a small PC board. This is coded SC09104911 and measures 108 x 28mm. The board, along with the recommended loudspeaker, can be installed in any carriage that's long enough to accommodate it; eg, a guard 's van or goods wagon. Before you start assembly of the board, carefully check the tracks for shorts or breaks. Any faults should be corrected at this stage. Also make sure that the board will fit into the selected van or wagon - you don't want to be doing surgery on it when it's full y assembled. Once you are satisfied with the PC board itself, take a look at the wmng diagram (Fig.4) , which shows how the components should be installed. Make sure you follow it precisely otherwise you may have problems fitting all the components onto the board because of the cramped conditions. Begin by installing the four wire links, making sure that they are flush with the board and as straight as possible. This done , you can install the resistors. These are all installed end on to save space, as shown in the wiring diagram and in the photograph. Uffi a pair of needle nose pliers to make neat right angle bends in the resistor leads. This will give your board a much neater appearance and reduce the possibility of shorts between components. Now you can install the monolithic capacitors. These should all have a fixed spacing of 5mm between their leads, regardless of their value. Don't try using greencaps here - they will be too bulky. After you've installed these capacitors, wire in the signal and power diodes. Make sure that the correct type is used at each position and that they are install·ed the right way around, otherwise the circuit may end up acting like a short circuit! Next, install the four transistors. The reason for doing these now is that they are lower in profile than the RESISTOR COLOUR CODES 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 No. Value 4-Band Code (5%) 5-Band Code (1%) 1 1 2 2 1 3 2 2 1.2MQ 560kQ 330kQ 150kQ 120kQ 100kQ 68kQ 27kQ 22kQ 15kQ 6.8kQ 1.8kQ 1.2kQ 1kQ 820Q 22Q 10Q brown red green gold green blue yellow gold orange orange yellow gold brown green yellow gold brown red yellow gold brown black yellow gold blue grey orange gold red violet orange gold red red orange gold brown green orange gold blue grey red gold brown grey red gold brown red red gold brown black red gold grey red brown gold red red black gold brown black black gold brown red black yellow brown green blue black orange brown orange orange black orange brown brown green black orange brown brown red black orange brown brown bla9k black orange brown blue grey black red brown red violet black red brown red red black red brown brown green black red brown blue grey 6Iack brown brown brown grey black brown brown brown red black brown brown brown black black brown brown grey red black black brown red red black gold brown brown black black gold brown 1 1 APRIL 1991 27 Three holes were drilled in the bottom of the carriage to let the sound out. The miniature loudspeaker sits in an adjacent rectangular cutout and protrudes slightly from the underside of the carriage. electrolytic capacitors. Once again, make sure that they are installed correctly. The pinout diagrams are on the circuit schematic (Fig.3). Now you can install the electrolytic capacitors. Although they may look a tight fit, these capacitors fit in snugly if you use the recommended voltage rating. Check that the polarity of each capacitor is correct, too. Finally, solder in the 7812 regulator and the LM324 op amp IC. You can easily identify pin 1 of the IG by the adjacent notch (or dot) in the plastic body. When you've finished, check _the board carefully for solder splashes and dry joints. If everything _is OK, you can connect up the loudspeaker and the train controller. To test the board, connect the track leads directly to the controller and apply power with the throttle fully closed. If the overload alarm sounds , switch off immediately and check your wiring for a short or an incorrectly installed component. If all is well, the circuit will make a continuous sound that simulates the noise of escaping steam. If you now open the throttle (that's railway talk for increasing the speed), the steam sound should slowly decrease in volume until the circuit begins to chuff. As you continue to open the throttle , the speed of the chuffing should also increase. Installation When you install the board inside the carriage, you can use Blu-tac® to Fig.5: this is the full-size artwork for the PC board._ 28 SILICON CHIP hold it down. The way in which the power supply is connected is up to you. You may wish to connect the power directly from the motor of the loco or you may wish to use a collector system from the wheels or rails. The choice is yours. We mounted our prototype into a New South Wales HO baggage car made by Powerline Models Pty Ltd (047 39 6204). We drilled three 10mm holes in the base of the carriage to let the sound escape and also made a rectangular cutout to accept the loudspeaker which protrudes slightly from the underside of the carriage. If you intend mounting the SteamSound Simulator underneath your layout baseboard, you can use a much larger speaker and thereby get a lot more sound. Another good idea which we tried was to have one SteamSound Simulator behind the loco and one underneath the layout baseboard. Because the two simulators are not synchronised, they give an interesting echo effect as the train moves around the layout. Which ever way you do it, you can now stop using your imagination and actually have the sounds of steam around your layout! (Oh, what joy! No more diesels ... oops! Only joking, of course!) SC wpoD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS ... 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Also checks for proper ean ing etc. US Modular type plugs and sockets for I rtc u:iJ~~rwer. Arrestor for maximum protection. Fully approved. $64.95 00%i~~~mgi~ SerialTest serial data analysis on your PC This is an MS-DOS software and cabling package which enables technicians and engine!rs to fierform sertal data comms analysis. t offers sophisticated problem solvin~ facil ities at a fraction of the cost o dedicated hardware systems. SerialTest provides a window onto RS232·Iines operating either as a passive observer or actively sending data or control signals to simulate either at DTE or DCE device. 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This gives you ample time to power down your system in the event of a mains failure. Instant switch-over. Battery 0 Ji EsJ~is~ri (S680.00 ex tax) ~ ~~~~~r~~J~~ai~~i);ted Allow $20 P&P .,, I::) () :i: ~ GEOFF WOOD ELECTRONICS PTY LTD 0 229 Burns Bay Road, (Corner Beatrice St.) iNc IN Nsw Lane Cove West, N.S.W. P.O. Box 671, Lane Cove N.S.W. 2066 0 Telephone: (02) 428 4111 Fax: (02) 428 5198. 8.30am to 5.00pm Monday to Friday, 8.30am to 12 noon Saturday. Mail Orders add $5.00 to cover postal charges. Next day delivery in Sydney add $5.00. .,, I::) :,;:, () ,,. All prices INCLUDE sales tax. Tax exemption certificates accepted if line value exceeds $10.00. BANKCARD, MASTERCARD, VISA, CHEQUES OR CASH CHEERFULLY ACCEPTED :i: 'ti "' Remote controller for garage doors, Pt.2 Last month, we presented the full circuit details for this project which essentially consists of a receiver/decoder board plus a ready built transmitter. This month, we give the constructional details and discuss how it can be used in a practical installation. By BRANCO JUSTIC We left off last month with a short discussion on the transmitter circuit which was shown on page 20 of that issue. It is supplied readymade and operational but it needs one component change and it must be coded. The component to be changed is the resistor connected between pins 15 30 SILICON CHIP and 16 of ICl. Shown on the circuit last month as lMQ, it needs to be changed to 220kQ. We suggest you change it and do the transmitter coding at the same time, to avoid unnecessary work. Before proceeding to modify the transmitter though, it is better to per- haps leave it for the moment in its supplied condition. So let's proceed to the assembly of the receiver/decoder board. As shown in the photographs, the receiver board has five SPDT relays mounted on it and these are supplied with the kit. We suggest that they be mounted on the board first, before all the other circuit components. There is just one small but very important point though. Five diodes and two resistors mount under those relays, so you'd better bung them in as the first step otherwise you will be more than a little cheesed off later on. Consult the wiring diagram of Fig.4 and you will see that the five diodes in question mount right underneath the relay coils. The two lOQ 1 W resistors actually sit between relays TO BATTERY POSITIVE Fig.4: this diagram shows the component layout for the receiver/decoder board, as well as the external wiring. Note that a diode sits underneath each relay coil and should be installed before the relays are mounted. The same goes for the two 10Q 1 W resistors. RLA 1 and RLA2, and between RLA3 and RLA4. 24 V operation Another diversion, before we get too involved with the construction, concerns the supply rail. We assume that most constructors will want to use a standard 12V automotive wiper motor and gearbox as the motive power for their garage door opener. These motors are quite efficient but have loads of torque since they are geared down a long way. Another option is to use a 24 V truck or bus wiper motor. If so, you will want to run the circuit at 24V. That means the two aforementioned resistors will need to be 120Q 2W units. We'll have more to say about the power supply arrangements later; back to the board assembly. Next, install the five diodes and two resistors and solder them in place. Make sure that the diodes are soldered in the right way around. It is important that the relays be carefully soldered into circuit, otherwise they will not work. Why? Because their metal frame is actually connected to the moving switch contact. If the frame is not soldered prop- erly, the relay will, for all intents and purposes , be open circuit. For that reason , make sure that the mounting lugs on the relay fram es are clean and bright. If they're not, clean them up with a Scotchbrite scouring pad. Don't, whatever you do , use steel wool. It will inevitably leave stray strands on the relay which will probably cause a future short circuit. When the relay mounting lugs are clean and bright, tin them carefully with your soldering iron (making sure that you only give them the lightest touch of solder). That done, push them all the way into their respective board holes and solder them to the board's copper pattern. You can now begin installing the smaller components, starting with the wire links, diodes and resistors. Note that some of the resistors are mounted end-on, because space is a bit tight. Now put in the capacitors. There are quite a few electrolytics - make sure that they are all correctly polarised, as shown on Fig.4, before you solder them into place. The last components to be mounted are the transistors and diodes and naturally, it is vital that they too are installed the right way around. Sock- ets are optional for the !Cs; use them if you want to. Finally, we fitted a 350mm insulated antenna lead to the receiver. We coiled the lead as shown in the photograph to keep the installation neat but it should be left straight if you want maximum range. When the board is complete, go over it very carefully to check component placement and your soldering. Fix any mistakes now. Now is the time to change that lMQ Our prototype was installed in a large plastic case, with the 12V light fitting mounted on the front panel. Also mounted on the front panel is the pushbutton switch which provides manual UP/DOWN operation. APRIL 1991 31 cut the relevant tracks to the data pins for ICl. Note that A4, A9 and All should be open circuit when you are finished (for this example, anyway) . Now, on the receiver/decoder board, use your soldering iron and a little solder to bridge (ie , short out with solder) all the desired high or low connections for Al, A2, A3, A6, A7, A8, A10 and A12. One thing you must be sure to avoid and is that you don't have bridges from one of the IC pins to both HI and LO. If that happens, you short the HI rail (which is protected on the transmitter board by a 10kQ resistor) and the circuit won't work. On the receiver, the 7808 providing the +8V rail should protect itself but the circuit still won't work. Power check This interior view of the prototype shows the receiver/decoder board and some of the external wiring. The battery is in place but not yet connected or bolted down. Note the coiled antenna lead near the lefthand side of the case. resistor in the transmitter to 220kQ, as mentionend at the start. Unclip the transmitter case, disconnect the battery, desolder the lMQ resistor and solder in the 220kQ unit. Now for the coding. The important thing to note about the transmi_tter and receiver coding is that they must be absolutely the same. If even one of the coding bits is different, you can press that transmitter button till the battery runs out and the receiver will continue to sit there and do nothing.Make absolutely sure that the coding is correct. How to code This part is where you program the transmitter and receiver with your own unique code. You do it by connecting various pins on the transmitter encoder (ICl) and the receiver decoder (IC2) high, low or leaving them open circuit. Fig.5 shows the general concept. It shows the copper PC pattern underneath both these ICs. You can see the IC pads and the HI associated HI (+V) and LO (0V) ~ rails. c» A1 c» C> A2· On the transmitter, there are tiny c» c». A3 tracks tying each data pin to the C> A4 c» c» A5 HI and LO rails. You'll need to cut A12 C> A6 one or both of these tracks on each A11 C> A7 A10 C> 0 AB data pin, to perform the coding. A9 On the receiver/decoder board, each of the data pins is unconnected and you will have to deRECEIVER TRANSMITTER cide whether to bridge each of the Fig.5: these are portions of the copper pins HI, LO or leave them unconPC pattern underneath the transmitter nected. encoder (IC1) and the receiver Now we'll give you an example decoder (IC2). You must cut one or of how to do it. both of the bridging tracks on all the Suppose you decide to make the data pins for the transmitter (left) and transmitter coding as follows: Al, use your soldering iron to bridge the A3, A6 and A10 all high; A2, A7, data pins HI or LO on the receiver. A8 and Al2 all low; and all other The coding for the transmitter and lines open circuit. To do this, you receiver must be identical otherwise the radio link will not work. simply use your utility knife to 32 SILICON CHIP To check the receiver/decoder operation, you'll need either a 12V AC or DC plugpack; it does not matter which. When power is applied to the receiver PC board, the light relay (RLA5) and the "Down" relays (RLA3 & RLA4) should operate. After about 2 minutes, the light relay RLA5 should drop out but RLA3 and RLA4 should remain latched. If the manual pushbutton is now pressed, the light relay RLA5 should once again operate, relays RLA3 and RLA4 should drop out, and the "Up" relays RLA1 and RLA2 should operate. To drop out the "Up" and the "Down" relays, you will have to operate the upper and lower limit switches respectively. Alignment The alignment procedure is quite simple since the transmitter is already aligned to 304MHz. You will need to make up the test circuit shown in Fig.6 . Connect it to test point TP1 on the receiver/decoder board. Press the .0033 TO TP1 - - - I I I - ~ . . - - - - - - , D1 OA90 GND1i------' .,. Fig.6: this little RF detector circuit is connected to test point TPl on the receiver board for the alignment procedure. You simply press the transmitter button & adjust CVl on the receiver for a maximum reading. HEAVY DUTY TV/SPEAKER WALL-CEILING BRACKETS The M83 and MB5 are heavy duty two platform mounting brackets designed for securing small TV's and speakers to walls, ceilings, desks or bench tops. When mounted both units can ~~'U7l ~~14l as well as being swivelled up or down to any viewing or listening angle. The metal platforms have predrilled holes tor mounting and are easily adjusted with a large alien key supplied with the unit. Imported and distributed by: .ABISTI\ ELECTRONICS Available through the following retailers: David J Reid All Electronic Electronics. Components. 127 York Street. 118 Lonsdale St. Sydney. 2000. Melbourne. 3000. NSW. (02) 267-1385. Vic. (03) 662 3506. ~{;!; A VIDEO DUBBING/ ENHANCING SYSTEM THAT DOESN'T COST THE EARTH. • Enhances Video and Audio Signals. • Mono/Stereo Compatible. • Simple Operation. • Can be used with most Video Cameras. This photo shows the motor drive arrangements on a roller door. The upper limit switch can be clearly seen. transmitter button and adjust trimmer capacitor CVl for the maximum possible DC voltage reading on your analog multimeter. As a point of interest, the prototype gave a range of over 200 metres with the antenna wire attached. Our prototype was installed in a large plastic case with a clear plastic lens on the top for the 12V garage light, switched by relay RLA5. Power supply details Inside the case is a standard multi- tap transformer (Altronics M-6672) with the 12V windings connected to the rectifier inputs on the board. Also installed is a 12V 6.5A/h sealed lead acid battery. This is connected as shown in the wiring diagram ofFig.4. This is trickle charged via an 82Q 1W resistor and it delivers power to the circuit and to the motor via a 1N5404 silicon rectifier diode. By using this power arrangement, the circuit will work all the time regardless of whether mains power is present or not - you still want to get The AVE SSL is easily installed and provides excellent results . 11111 ALL THIS FOR $49.00 (Includes P & H). ---------- TO ORDER Please mail coupon to: I I SOUNDRING PTY. LTD. PO BOX 154, CAMMERAY NSW 2062 I I Please send me _ _(Qty) AVE SSL video I systems. I dubbing/enhancing My cheque/money order or credit card de· I I tails for$._ _ _ are enclosed. I Name._ _ _ _ _ _ _ _ _ I I Address._ _ _ _ _ _ _ _ _ _ I I Phone._ _ _ _ _ P/code I Tel: (02) 967 2411 Fax: (02) 958 7199 ~------------~ APRIL 1991 33 A typical motor drive arrangement for a Tiltador. A length of 1-inch water pipe serves as a carrier for the linkage for the door and it is driven back and forth by the bicycle chain. Here is a closeup view of the main drive gear on the roller door. This one has been welded but there is no reason why it could not have been attached with bolts and spacers to the inner frame of the door. This is a commercial installation on a panel lift door but the principle of operation is very much the same as the Tiltador example. The main spring is part of the original door mechanism. into your garage during a blackout. Using the battery also means that the transformer really only has to trickle charge the battery, not drive the motor directly. Installation details The actual installation will depend on your type of door. To give you a good idea of how it can be done, we'll let the photos included with this ar34 SILICON CHIP tide do the talking. All are based on chain drive using readily available bicycle sprockets. Some of the brackets used in the photos have been welded but there is no reason why you can't use all bolted construction or brackets made of timber, provided they are strong enough. Once you have your installation complete and working, you will need to ensure that the top and bottom limit switches do work as desired and that the over-current trip circuit is adjusted. To set the over-current adjustment, place an obstruction such as a cardboard carton underneath the door. Set the lower · limit adjustment VR2 so that the descending door does not crush the carton but does not tend to stall when starting. To set the upper limit adjustment, get someone to hang onto the door to give it some extra load. Again, set the adjustment (VRl) so that the door · does not stall when starting but will stop when given an extra load. Finally, note that there are a few changes to the receiver circuit which have been incorporated into the final PC board layout of Fig.4. First, the lkQ resistor connected to one end of choke RFCl is now 2.2kQ and extra bypassing components (a 4.7kQ resistor and lOµF capacitor) are now incorporated into the supply line for Ql. Second, pin 12 of ICla is connected directly to ground and the lOMQ resistor is deleted. And third, the pin numbers for IClc and ICld on the receiver circuit are actually swapped on the board layout. SC MARCH MADNESS CONTINUES THROUGH APRIL, FACTORY PRICES ON COMPUTER CASES ry~~;s;;t; ;~ill b;th; ;;v; ~fe~;;y~;;;;iththis-p-;.~;;;,io~7ti' upright case. SAVE $124.00 Only a few units left. Catalogue Number: CAMTP This vertical case is perfect for your new or existing XT, AT or 386 computer. It has a smoke glass flip cover to keep dirt out of your disk drives as well a front on/off switch and keyboard socket. Provision for boards with eight expansion slots and dual fans to keep everything cool. This case has a 230 Watt heavy duty power supply. Dimensions 16" x 15.75" x 7.75". Plus features most cases can only dream about: * Provision for 3 x 5¼" and 2 x 3.5" drives. * Speed display in MHz with two inbuilt settings to suit most motherboards. * 4 LED indicators with wiring installed. * Turbo switch. * Inbuilt speaker. * Complete with hardware kit. * Heavy metal construction. . BE QUICK, never to be repeated only $275.00 ~--------------------------------------✓ Switching Power Supply - 150W This 150 watt power supply can be used as a direct replacement for IBM XT's and compatibles. It is much more rugged than the original supply, making it ideal for systems with a number of peripheral devices. It comes complete with power leads for both hard and floppy drives as well as power connectors for the motherboard. Has full short circuit and overload voltage protection. Dimensions 225mm x 140mm x 120mm. This month only $99.00 r-------: --------, 1.8 metre Printer Cable r-----------1 RodentMat 1 Thisrodentmatissensitiveandgivesyou accurate comfortable tracking. It also helps I prevent dust, dirt and dampness from I clogging up your rodent. There is also a special rubberized backing to avoid I slipping. Don't let your rodent get away 1 This one is of high quality and has IBM compatible connectors I on each end. Get a spare one today for 'n'T"ll""'''4''rir49,:stBtr times when you just have to I those print and don't want your cable to I let you down. 1 I I I 1 Only $10.00ea 11 ' , ..,..,,..., -. from you. This month only $5.00ea , 1 1 I I I 1 ~-----------~----✓~------------------✓ IAN'S PERSONAL GUARANTEE * All products carry a 14 day money back guarantee ( except software and hard disks). * All prices include sales tax. * All motherboards carry a full 12 month warranty. * .All cards come with full documentation * All other products carry a full 3 month warranty. Due to Technical advances, products we supply may in some cases vary from those pictured. In all cases the products supplied are guaranteed to perform to an equal or higher standard than those pictured - WHOLESALE ENQUIRIES WELCOME I V/SAi ·-------------------1 Send us this coupon to receive your FREE 1991 Catalogue: Electronic Solutions 5 Waltham StArtarmon 2064 PO Box 426 Gladesville 2111 Telephone: (02) 906 6666 Fax: (02) 906 5222 I Mr/Mrs/Ms:_ _ _ _ _ _ _ __ _ _ _ _ _ __ I I Address:._ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ I Suburb:_ _ __ _ _ __ __ State:_ _ _ _ _ Postcode:_ _ _ I previously issued card to be included on the mailing list, as you will receive the catalogue automatically. 04/91 I I I Note: Please do not return this coupon if you purchased from us in 1990 or returned the I ·--------------------------· VINTAGE RADIO By JOHN HILL Converting an Airzone to AGC Although automatic gain control (AGC) became common in receivers from the early 1930s on, · there were a number of sets made at around that time which lacked this useful refinement. This month, we look at how a 1937 Airzone receiver was fitted with AGC. It was one of those things that I had been meaning to do for some time. In my collection of old radios, there is a rather stately looking Airzone - a 1937 console model which has no AGC. Just why it lacks AGC is a bit of a mystery, for nearly all radios of that era were fitted with this feature . At one stage, I suspected that an This is the 5-valve Airzone that was converted to AGC. It is a 1937 console model with a 10-inch electrodynamic loudspeaker. Adding AGC makes it a far more pleasant set to use. 36 SILICON CHIP AGC circuit must have been lurking in there somewhere but had become inoperative. However, a close inspection of the chassis (as best as one could without a circuit diagram) soon confirmed that the set had never had AGC. There were two reasons for this .conclusion: (1). the receiver had no valves which contained diodes; and (2). the volume control was a wire- wound potentiometer in the cathode circuits of the frequency converter and IF amplifier valves. Clearly, the set was never designed for AGC. The valve complement (confirmed by a sticker inside the cabinet) is as follows: 5Y3, 6A8, 6U7, 6J7 and 6F6 . This is a fairly standard. layout for ·a 1937 5-valve receiver, with the exception of the 6J7. Most sets of that vintage would use a 6B6 or a 6B8 instead. Both these valves contain diodes which would have made AGC easy to implement. Valves with diodes As explained in last month's column, there was a change in superhet design in the early 1930s, when valves containing diodes were first intro- The Airzone chassis. The valve complement is as follows: 5Y3, 6A8, 6U7, 6J7 and 6F6. This is a fairly standard line-up for a receiver of that era with the exception of the 6J7 (most sets would have used a 6B6 or 6B8). duced. These diodes could be used for both an improved form of detection (diode detection) and a more practical form of AGC than any previous attempts. Along with these changes came a change in volume control methods. The volume control was moved from the cathode circuit of the IF valve(s) and, in some cases, the frequency converter as well, to the control grid of the first audio valve. An AGC circuit rectifies the received signal and produces a negative voltage which is directed back to the grids of the IF and converter valves, to control their gain. Strong signals increase the AGC voltage, which reduces the gain, whereas weak signals have the opposite effect. As AGC circuits work with variable mu valves, there was little reason why the old Airzone could not be converted to ACC. Both the frequency converter and the IF amplifier valve were common types, as used in con. junction with AGC in other receivers. All that was needed was to add a couple of diodes and a few other bits and pieces. Conversion options There were a number of ways to approach the diode problem. First, a different first audio valve such as a 6B6 or a 6B8 could be fitted, which would have a pair of diodes in the same envelope. Another possibility was to fit a separate twin diode valve, thus retaining the existing 6J7 as the first audio valve. As a last resort, a couple of modern solid state signal diodes would do the job just as well as any thermionic type - do I sense some readers throwing up their hands in horror? In any case, if the 6J7 is to be used as a straight audio amplifier, rather than a detector, its operating conditions should be changed. As a detector - almost certainly an anode bend detector - it would be biased close to cut-off, using a high value cathode resistor and, possibly, a low screen voltage. This would restict its operation as an amplifier. In 'the end, I decided to install a 6H6 twin diode valve. One reason for this decision was the fact that the chassis already had provision for an additional valve. Fitting the 6H6 was as easy as removing a cover plate and bolting in a new socket. The heater The 6H6 twin diode was made in both metal & glass envelope versions. At least the glass version looks like a real valve, even if it is rather small. pins of the 6H6 socket were wired to the heater pins of a nearby valve. An AGC circuit was required and the one shown in Fig.1 was taken from an old radio book. There are some variations in AGC circuits (eg, simple AGC and delayed AGC - see last month's story), and some look far more complex than others. The circuit used requires only one diode and so the 6H6 anodes and cathodes were connected in parallel to form a single unit. The next step was to fit a new volume control. A 500kQ carbon pot was installed in place of the old wirewound pot. However, although the old control was removed from the chassis, it was left connected in circuit. Mere about that later. AGC-----, The new volume control was wired in accordance with Fig.1, with the wiper arm going to the 6J7 via an existing .01µF capacitor. Also added were the various resistors and capacitors needed for the AGC circuit, plus the h eater wiring for the 6H6. The circuit also shows the changes made to the 6J7 circuit. This . left only the two AGC outlets to be connected. These two AGC lines had to be connected to the control grids of the first two valves, via the first IF transformer's secondary winding in one instance, and the aerial coil secondary winding in the other. However, it was not just a matter of connecting the AGC lines to existing connections, because they were both connected to chassis. 0 -----1---HT 1.5MI 1M .01 1M' .,. Fig.1: the AGC circuit produces a negative voltage and this is applied to the grids of the first two valves, via the aerial coil secondary winding in one instance & the first IF transformer secondary winding in the other. APRIL 1991 37 Only a handful of components was required to convert the old Airzone to AGC. The 6H6 twin diode was chosen so that the original 6J7 first audio valve could be retained but other approaches should prove equally viable (see text). • • The 6H6 twin diode valve was easily fitted to an existing valve socket hole in the chassis of the old Airzone. These connections need to be carefully traced back from the valve grids and unsoldered from the chassis, so that the AGC lines can be connected to them. After the AGC lines were connected to the coil terminations, these points were bypassed to chassis via O. lµF capacitors. At this stage everything was ready for a trial run. Initial results The initial results were a bit disappointing. The AGC additions had thrown the front end of the receiver considerably out of whack. Motor38 SILICON CHIP boating, whistles and howls indicated that all was not well and there was a brief moment when I reflected on the wisdom of drawing up the original circuit in case the set had to be returned to "as it was" condition. At this stage I was glad that I had left the original volume control in circuit. It was, in fact, nothing more than a variable resistor in the cathode circuits of the first two valves, and capable of providing variable cathode bias for them. That was all that was needed to correct the instability. After finding a position where everything worked reasonably well, the potentiometer resistance was measured and a fixed resistor fitted in its place. The set was greatly improved by the AGC conversion but I was still a little disappointed regarding its effectiveness. Strong stations were still fairly strong, while weak stations were still inclined to be weak. Out came the single substitute cathode resistor and in went two 5kQ pots; one in the frequency converter cathode and the other in the IF amplifier cathode. With the set tuned to the noise between stations (virtually no signal), the volume level could be brought up quite noticeably by fiddling with each cathode resistor. After replacing these pots with fixed resistors the AGC was more effective (Note: the cathode resistance was determined simply by setting the pots for maximum volume without instability). These adjustments made a significant difference to distant stations but seemed to have had little or no affect on close stations. One noticeable change with the AGC conversion was that the receiver needed retuning. This was particularly evident with the first IF transformer, which had its secondary circuit upset by the addition of the AGC line. A complete re-alignment of the receiver was in order and, while it was not badly out, there were noticeable improvements when the job was finished . The conversion turned out to be quite successful and I love the old Airzone even more than before. Other conversions Flushed with success I decided to convert another 1937 set, a console model Playola. Although fitted with a 6B6 and using diode detection, the receiver had no AGC, which seemed a bit cheap and nasty to me. It too responded well to the conversion and is now a far more pleasant set to use. The third and last radio to be converted (a 1934 model Commodore) was a little different. It uses a 57 as an autodyne frequency changer, followed by a 58 IF amplifier, and has no diodes. In this instance, a germanium signal diode was used, with only one valve, the 58 IF amplifier, being AGC controlled. (The old 58 was one of the first variable mu tubes to be made). Resurrection Radio Vintage Wireless Specialists Repairs - Restoration - Sales Our skilled technicians offer QUALITY repairs and restoration. We also have a large stock of Bakelite and Timber radios fully restored and for SALE. This temporary test rig shows that the AGC circuit produces a negative voltage (the larger the signal, the higher the voltage). This negative bias is directed to the grids of the pre-detector valves. The frequency changer was not suitable for AGC control for two reasons: (1) the 57 is not a variable mu tube; and (2), an autodyn e freque ncy changer is notoriously cranky (even a minor change in operating conditions can cause it to stop oscillating). The old Commodore responded fairly well to the treatment, considering that AGC is applied to only one valve. It certainly is a big improvement on no AGC at all. Converting a receiver to AGC can easily introduce other problems because the circuit has been interfered w ith. Th ere may be other methods of solving th e problems I encountered, but th e sets I converted all work well, an d that's what matters most. Altogether, these three AGC modifications took quite a bit of time to do, but they were worth both the time an d effort. It was an interesting project and the addition of AGC made all th ese receivers far more pleasant to operate. SC Parts are available for the enthusiasts including over 900 valve typ es, high voltage capacitors, transformers, dial glasses, knobs, grille cloth etc. Circuit diagrams for most Australian makes and models. Send SAE for our catalogue. WANTED - Valves, Radios , etc. purchased for CASH Call in to our Showroom at: 51 Chapel Street, Windsor,Vic 3181 PO Box 111 6 Telephone: (03) 529 5639 UHF HIGH GAIN ANTENNAS antenn existing systems triangul powder coated receiving elements ensures excellent UHF reception compared to other UHF antennas of similar size and price. Two models are available: the TVA14 for Band Four and the TVA 15 for Band Five UHF reception. Both models are supplied with back reflectors to prevent ghosting as well as a waterproof entry box designed to accept 75 ohm coaxial cable without the need for addittional baluns. They also have predrilled holes for securing the tilt adjustable metal mounting bracket in either a horizontal or vertical position . ./mported snd dis tributed by: ARISTA ELECTRONICS Avsllsbte through the following retailers: This simple AGC conversion module was built up on tagstrip & fitted to a 1934 model Commodore receiver. In this case, a germanium signal diode was used, with only one valve, the 58 IF amplifier, being AGC controlled. The tagstrip method makes the conversion a bit neater than the more usual point-to-point wiring method. B ernys. Bridgepoint. Military Road. Mosman. 2088. NSW. (02) 969 1966. Ritronics. 56 Renver Rd. Clayton. Victoria. 3168. (03) 543 2166. A PRIL 1991 39 SERVICEMAN'S LOG Mystery, mystery & frustration This month, I have three short stories, two of which introduce an element of mystery and the third a sense of frustration. It is unlikely that we will ever know the answers to the mysteries but the cures were obvious. The first story concerns a Toshiba 48cm colour TV set, model C-2020. As is often the case, the customer's complaint over the phone was rather vague. His first statement was to the effect that "it keeps going off", but further remarks suggested that the "off" was poor performance rather than total failure. And the "keeps going" suggested it was probably intermittent. Anyway, I suggested he bring it in for closer inspection. So he duly turned up and I set it up while he was there. The picture was faint and lacking contrast. I forced it up to a more recognisable level with the brightness control and was then able to see that it was riddled with hum. The vertical:; were weaving back and forth and it was also displaying hum bars. Well, it looked like a snack. It was obviously a power supply fault and this was a power supply with which I was very familiar. I mentally registered that it was almost certainly the main filter capacitor, C810, a 680µF electrolytic (top of Fig.1). I'd seen the symptoms many times before . At the first opportunity, I pulled the back off and checked the HT rail. This should be about 110V but was only 86V, measured at the emitter of the regulator (Q801). On the other hand, the collector was at 133V which is almost spot on. This raised some doubt about the capacitor but per- haps not as much as it should have. Anyway, I rustled through my stocks for a replacement. As it happened, I didn't have an exact replacement but I did find one that would do, but which would need some extra work to fit. By now I wasn't so sure about the capacitor and, with the need to do this extra work, I was less inclined to rush in. I tacked a couple of leads onto the capacitor, then patched it into circuit across the suspect unit. It had no effect whatsoever. So much for my original "snack" diagnosis; it was time to stop guessing and start working. The circuit is not particularly complex and is quite conventional. There are three transistors: Q803, error detector (bottom of diagram); Q802, regulator driver (above it); and Q801, which is the main regulator (top of diagram). The other major component is the bridge rectifier, consisting of diodes D801, D802, D803 and D804. I went immediately to the voltage adjustment control, R851, a 1.5kQ variable resistor in the base circuit of the error amplifier. This sets the HT rail to the required voltage but I wasn't really surprised that adjusting it had no effect. Next I made a preliminary check of those minor components most likely to have upset the regulator action and, while I couldn't be absolutely certain, all the indications were that these were OK. Which transistor? So that left the transistors. Both the error amplifier (Q803) and the regulator driver (Q802) have given trouble in the past, with the symptoms ranging from the simple to the weird. The regulator transistor can fail just as readily as the other two, but it is normally a catastrophic failure; breakdown between emitter and collector, creating an excessive HT rail voltage (typically around 135V) and causing 40 SILICON CHIP C+)f2y) QBOI 2SCI 195 FA-I POWER REGU, GRN I L1 ~C809 R_~ii(G) USOI D813 - 3,3)1 (160V L901 1S1942 APF SWITCH TSB-2056<2055> DEGAUSSING COIL POWE_R_B_OA_R_D~PW~-~,,~10._. Fig.1: the power supply circuit for the Toshiba C-2020. Q801 is the regulator transistor, Q802 the driver transistor, and Q803 the error amplifier. the set's protective circuits to shut it down. So where should I start testing? Murphy's Law states that whenever a faulty component is one of a string, it will always be at the end opposite to that at which one starts. And if one attempts to minimise this effect by starting in the middle, it will always be at the far end of the last leg checked. But I had to start somewhere and, Murphy aside, I had a funny feeling that this time it was the regulator transistor (don't ask me why). So I disconnected the base and emitter leads and made a simple ohmmeter check in the time honoured fashion. This failed to reveal anything amiss, even when I went looking for leakage. Nevertheless, the funny feeling persisted and, with the leads disconnected, it was just as easy to try a replacement. I didn't have the exact replacement (2SC1195) but I found a BU126 which is an acceptable substitute. It took only a few minutes to fit it and - presto! - that was it; a normal picture and no hum problems. All that was needed was a marginal adjustment of R861 to bring the HT rail down a few volts. I ran the set for the rest of the day, with no sign of trouble, than rang my customer with the good news. As stated earlier, there was a hint of intermittency in the customer's original complaint but there was no sign of it on my bench. In any case, subsequent follow-ups confirmed that all was well. Transistor checks? But I was still puzzled as to what was wrong with the transistor. Granted, the simple checks I made are not always conclusive and, for this reason, I use a curve tracer as a back-up in sticky situations. So I hooked the tracer up to the CRO, set it up for power transistor checking, and tried the transistor. And it traced out a virtually perfect curve. So, was it breaking down - or something - at the higher voltages in the set? It is possible to vary the operating conditions of this equipment to a limited extent, so I adjusted the settings to increase the base current and also to increase the collector sweep voltage, within these limits. But there was still no sign of a fault. I left it running like that for an hour or so, at the end of which time the transistor was quite hot; I could touch it briefly but it was too hot to hold. And still a perfect curve. However, this involves only relatively low voltages; not more than 30V on the collector. And that's about as far as I can go. I still think the most likely explanation involves the higher operating voltages which I cannot duplicate. But now, having made these checks, I would dearly like the chance to put it back in the set, or another one like it. This is out of the question at the moment but I'm keeping it handy, should the opportunity arise. So for now, the mystery remains. A record for rarity The next story also poses a mystery but of a completely different kind. And it must surely set some kind of a record for rarity; I'd be prepared to bet long odds that no one has ever encountered it before. Rash words? Well, see what you think. The culprit was a Mitsubishi model CT-2963 68cm colour TV set. It was brand new, straight out of the carton at my local retailer colleague's shop. It is an upmarket model which, in addition to the large screen, boasts a flat, square picture tube. An intriguing aspect of the set was that it was made in Scotland. A Mitsubishi TV set made in Scotland! it's almost a contradiction in terms. Perhaps these sets should be renamed Macsubishi? All right, so I digress. Now to business. My colleague had unpacked the set, to put it on display, when a preliminary check indicated that all was not well. So he brought it around to me, complaining that "it's got hum on the picture". The model was new to me, apart from showroom acquaintance, and I APRIL 1991 41 SERVICEMAN'S LOG - CTD .,~9,... _ ~ ..... A. N\\-r"SOS\SHl -rv se..-r ff. .. N'A"DE- IN ~-n.ANT)f had no data on it. So my first reaction was that I would have to obtain a manual. But I thought I might as well have a look at it anyway, just to confirm my colleague's symptoms. So I unpacked it and set it up. And as luck would have it, it was switched to SBS which was running a test pattern; I couldn't have wished for a better demonstration of the fault . On the other hand, describing the fault is not easy, so please bear with me. Those familiar with SBS will know that, superimposed on the test card itself, are two running displays, one near the top , carrying program data and channel data, and one near the bottom of the picture, carrying the title and other data on the music being played. And it was the bottom display which exhibited the fault. The message comes in from the right and this was quite normal for the first few centimetres, until it reached the first vertical colour bar; green at the top and blue at the bottom. Here it kicked upwards for about 15cm, then ran downhill towards the centre of the screen, where there is a short red colour bar. From here it ran uphill and traced what was virtually a mirror image to 42 SILICON CHIP the left hand side of the screen; up to the magenta bar, a short downward kick, then straight out the left. Any ideas? Forget it; you'd never guess it in a month of Sundays . Shock, horror My own reaction was one of bewildered shock. I could understand why my colleague had described it as hum. He is familiar with the classic hula girl pattern caused by hum in the horizontal system and, with his limited technical knowledge, assumed something similar in the vertical system. And, while I ruled out hum, I went through the mental exercise of trying to visualise what kind of vertical waveform distortion could cause such an effect. After a couple of tries, I gave up; the brain simply refused to cope. I let the set run while I went on with a couple of other jobs, hoping for inspiration. None was forthcoming - at least not directly. But while working on other sets, I had been made more aware of the difference in picture tube faceplate curvature, between the old tubes and the new. When I went back to the Mitsubishi, I idly ran my hand over the tube, mentally assessing the curvature - just to reassure myself that it was not truly flat. It was not of course - it was significantly convex, just as I knew it would be. At least most of it was. When I ran my hand across the bottom of the tube I suddenly realised that a particular area (need I say where) was not convex but concave, with about the same order of curvature as 'the convex area. So that was it; it wasn't an electronic fault at all, it was an optical effect caused by a distorted picture tube faceplate. And that was the end of the exercise as far as I was concerned; the set was going straight back to Mitsubishi. The warranty payment for changing a picture tube is not exactly generous and their service department can do the job cheaper than I can. But my main reaction was that I wanted the thing out of my workshop as quickly as possible. Maybe I was over reacting but I felt sure that any tube with a distorted faceplate - and certainly one as bad as this one - was a prime candidate for spontaneous implosion. (I've seen the result of an implosion and it isn't funny). I don't know much about the glass technology of picture tube design but I do know that the curvature is a vital factor in tube strengtp.. And I understand that the so-called '"flat" tubes have only been made possible by modern computer design techniques, which have been able reduce the curvature significantly while retaining an acceptable safety margin. That, in my language, means that they have pushed the design about as far as they dare. Not that there is anything wrong with that in itself, but does it allow for the kind of distortion I found in this tube? More to the point, how did this tube ever get into the field? How did it pass the tube manufacturer's inspection and how did it pass the set manufacturer's inspection? The drifting Tandy My next story concerns a Tandy 48cm colour TV set, a CTV-2001. It's not a very profound story technically but it does emphasise some of the day-to-day problems and traps one encounters. One problem was to get a clear history of the fault, which came in dribs and drabs. The set came to me from a local Tandy dealer, who had sold it to one of his customers. It was a new set and still under warranty. The customer's complaint was that it "drifted" off channel after running for some time. Fortunately, I have a colleague - a fellow serviceman - who works for another Tandy outlet several suburbs away. The local Tandy dealer had approached him first , since he had the service facilities, but had been redirected to m e. The main reason for this was the distance involved. Everyone is anxious to avoid transport costs these days, so my colleague suggested th at I could handle the job. The warranty situation did not present any problem, even though I do not normally handle these sets on this basis. The plan was for the Tandy dealer to pay me normal rates, then straighten this out between the two . Tandy outlets. That was about as much information as I had when the set came to me and so I immediately rang my colleague, first to confirm the arrangement and second to find out what I could about this particular model. I Mitsubishi/AWA AV10 Symptom: no sound or picture. All mechanical functions are normal and the machine will record normally for playback on another VCR. Playback audio and video are present at the NV output sockets but not via the RF out. Cure: RF modulator unserviceable. The usual procedure is to replace the modulator at considerable cost. However, replacing the TA7673 IC in the modulator is worth a try. The chip is cheap and has cured the problem on at least one occasion . TETIA TV Tip is supplied by the Tasmanian branch of The Electronic Technicians' Institute of Australia. Contact Jim Lawler, 16 Adina St, Geilston Bay, 7015. didn't even have a circuit. The business side of things was quickly confirmed and we moved on to techicalities. On the basis of the APRIL SPECIALS FROM RAYTEC MOTHERBOARDS 11 12MHz 8088 31MHz 8088 $109.00 $189.00 12MHz 80286 $299.00 16MHz 80286 Neat $449.00 16MHz 80386 $899.00 TV TEST EQUIPMENT THAT WILL EARN YOU MORE MONEY CASES Baby AT 200 W P/S $249.00 Mini Tower 200W P/S Maxi Tower 200W P/S $299.00 $399.00 KEYBOARDS 101 Enhanced Keyboard $ 89.00 GRAPHICS CARDS VGA VGA II _ MEMORY 2 Mb AT OK RAM 256K 16Bit $225.00 512K 16Bit $299.00 I POWER SUPPLIES XT 150 Watt AT 200watt $ 99.00 $149.00 I CARDS 32Mb XT/AT OK RAM I I $199.00 $299.00 MOUSE Mouse for PC XT/AT (AUSTRALIAN MADE) 12 Months Warranty S ORTED TURNS TESTER Built-in Meter to check EHT transformers including split diode type, yokes and drive transformers. $78.00 + $3.00 p&p .HI-VOLTAGE PROBE Built-in meter reads positive or negative 050kV. For check ing EHT and focus as well as any other Hi-tension voltages. $98.00 + $5.00 p&p LOW VOLTAGE PROBE Ideal for checking microwave ovens and TVs. The ranges are from 0 to 5kV Negative and from 0 to 10kV Positive. Double insulated for safety. $94 .oo $ 99.00 • Systems built to your personal requirements. • We stock a full range of Roctec external disk drives. • We also carry a full range of monitors, disk drives, modems, printers and other computer accessories. • Enquire about our comprehensive range of Australian made lighting surge arrestors, power and telephone line filters as well as standby and uninteruptable power supplies. • Phone today for details and competitive pricing. liiiiMiil * Mail and phone orders welcome. _ _ _ _ - ~ RAYTEC DATA SYSTEMS Phone (043} 23 1966 Fax _ (043) 23 3760 _ _ _ symptom:,, my colleague suggested that I look immediately at the tuner control board. Though these sets are very well made in most respects - a fact that I confirmed later - they appear to have one weakness. To understand this it is necessary to jump ahead a little and describe the layout of the set. The main board is about 25cm square and sits in the bottom of the cabinet, mounted in a reasonably substantial moulded plastic frame to give it additional strength. The whole assembly is held by four screws, one at each corner. This plastic frame also serves to support the tuner control board which is a narrow board, about as long as the main board is wide. This is mounted vertically on the main board at the fron_t of the cabinet, in a vertical section of the moulded plastic frame. The top edge of the control board sits just below the bottom of the picture tube. This board carries the tuner programming ICs and all the front panel controls. The tuner itself is mounted on the rear of the main board, allowing the antenna coax to connect directly to it. So what was the weakness? Accord- TETIA TV TIP PO Box 1174 Gosford Sth, 2250 • Freight chartge on normal size Items $10.00. Monttors etc. $15.00. • lnsurnce charge is 1% of total order value. PRICES VALID FOR THE MONTH OF PUBLICATION OR WHILE STOCKS LAST + $5 .oo p&p DEGAUSSING WAND 7,700 apere turns. Strong magnetic field, larger than usual coil with multicore centre. Double insulated for safety with momentary on/off switch. 240V A/C 2.2 amps. $75. This one is just about as important as having a soldering iron in your toolbox' . 0 p&p r'_:. . . . . ., REMOTE CONTROL TESTER ~ , r'\'\ " ,. '.J;y $85.00 + $4.00 p&p TUNER REPAIRS (INFARED OR ULTRASONIC) Designed to test any lnfared or Ultrasonic control units. With the extension lead you can also test infared units which cannot be placed in front of the testing unit. Requires a 9V battery . Output is via the LED diode and piezo speaker. from only $11.00 + p&p Chekque,dMonMey Order,d 8 an ea~ or asterca~ TIJNERS[\216 Canterbury Road, Revesby, ~ NSW, 2212, Australia Telephone (02) 774 1154 We also repair most tuners on an exchange basis. TV 1'• • APRIL 1991 43 SERVICEMAN'S LOG - CTD ing to my colleague, it was the "just below" which wasn't "below" enough - if you follow me. In other words, the tuner board was too close to the bottom of the picture tube. And the end result was that, if the set received a moderately severe jolt, as in transit, the board and picture tube could come into contact with enough force to crack the board or, at least, some of the tracks on the board. It had happened on a number of occasions and was now the first thing to be checked whenever any tuning problems were ,encountered. Hence his advice to check this board. Which brings us to the point where I had the set on the bench and was ready to turn it on and see what happened. The first surprise was that , there appeared to be no channels programmed into the tuner. Initially, I wondered whethe:r this was a manifestation of the drift problem but, fortunately, I had occasion to talk to my colleague again before I acted on this thought. It was then that I learned that the set had only ever been used with a video recorder. In fact, it was used in a coffee shop/milk bar to play video clips for the entertainment of its teenage patrons. So it had only been programmed for channel 1. Since it was easier to use off-air signals, I set to and programmed the tuner for the local VHF channels, plus SES on the UHF channel. Then I switched it to channel 2 and let it run. It ran like this for some hours, with no sign of trouble, which didn't seem to tally with the description of the fault - at least in terms of time. ·So I turned to the pattern generator, set it to channel 1, and fed the signal into the set. And that did get results; in a very short time, the signal started to drift. This was a bit puzzling, so I repeated the test on some of the high band VHF channels and also on the UHF channel. They were all rock steady. By now I was having definite second thoughts about the cracked board theory; the selective nature of the fault suggested an internal tuner fault. But, in any case, the board had to come out for inspection; if there was a "funny" due to damage and I missed it after being warned, I'd never hear the end of it. I pulled the back off the set and then, on impulse, tried another tack. I ran the set on all channels in turn, at the same time applying pressure and a twisting action to the tuner. None of this had any effect until I reached channel 1, whereupon it responded immediately; by applying the twisting action in the right direction and with the right pressure, I could virtually tune the signal in or out. This was even more evidence to support the faulty tuner theory. But I still had to clear up any suspicion of a cracked board. I pulled the board assembly out, unscrewed the control board from its frame - to get it in a good light - and went over it carefully, using a jeweller's loupe. After much searching, I was forced to the conclusion that there were no cracked or damaged tracks. While it was thoughtful of my colleague to warn me - and I'm passing the warning on - it was not the problem this time. .1.m.,.;. r.:.1;i:.11: RCS Radio Pty Ltd is the only company which manufactures and sells every PCB & front panel published in SILICON CHIP, ETI and EA. 651 Forest Road, Bexley, NSW 2207. Phone (02) 587 3491. 44 SILICON CHIP So back to the tuner. I turned the main board over and examined the various soldered connections to the tuner pins, again with the jeweller's loupe. I could find nothing wrong. I then set up a meter to monitor the tuning voltage but again drew a blank; it was perfectly steady. Finally, more or less in deperation, I went over the soldered connections and remade each one. It was more to be able to say that I had done it than any real hope that it would effect a cure. Imagine my surprise, therefore , when I set everything going again and found that the fault had vanished. None ofmy previous tricks to bring it on had any effect. So what had I done? Had there been a faulty joint which was not visible? Perhaps, but I was not convinced. The whole setup just didn't jell. I couldn't reconcile the channel selective nature of the fault with a faulty joint. Nevertheless, the set ran for the rest of that day without missing a beat, in spite of all the twisting, pressing and bashing I could dish out. Murphy's little joke So I finished up with a conflict of ideas. The more emotional line of thought wanted to believe that the fault was fixed; the commonsense line told me that such a cure just wasn't on. It was all one of Murphy's horrible jokes. But the set ran all the next day and all the following day. By this stage, I was about to send it back to the customer but then, on the fourth day, there was the fault, exactly as before. It was a narrow squeak. More to the point, I had no doubts now that it was an internal tuner fault. And that meant a new tuner, which seemed simple enough until we tried - and by "we" I mean the Tandy personnel as well as myself. The final answer was: "On back order; delivery date uncertain." I didn't go into the finer details of this situation, or who or what was to blame. Suffice it to say that there seemed to have been a miscalculation somewhere. But that's not unusual. So the set is sitting in a corner of my bench, waiting until a tuner becomes available. In the meantime, I have left it to the Tandy dealer to make peace with his customer. It's all very frustrating. SC ,AH t l t l , I H UN K ;:; :AA ELECTRONICS :AR ELECTRONICS 'ARELECTRC•"nn JAYL;AH l:Ll:l,; I HONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS ""Mn-• -n-nn.,.nn JAYCAR JAYCAA JAYCAR •• ••n • n ELEC TR ONICS JAYCAR ELE CTRONICS ELECTRONICS JAYCAR ELECTRON ICS ELECTRONICS JAYCAR ELEC TR ONICS -• - n-nn.. " - • - - • -n-nn , .. nn J AY CAR JA YC AA J AY CAR .. .. n • - ~m... . . ..... ···· ··· ···· · · · · · · · ··· · ·· ····.·. .· .· .·. · ·····- -· --11 := ~t~gi=g / : ~ ? ARELECTRC AR ELECfRC ) STEAM SOUND AA ELECTRC AR ELECTRO AR ELEClRC AR ELECTRC AR ELECTRC AR ELECTRC .... / :::: ) ) { Ref: SI II con Chip Aprll 1991 T~ls kit ls a4 channel tight chaser. Each channel will hardle up lo a36W globe. Dress up your car, truck, etc. A novel approach for a brake warning light? Kit Includes PC board and components. No globes supplied. Cal. KC-5092 RAILMASTER TRAIN ONTROLLER Ref: SIiicon ChlpAprll 1991 Had enough of Iha! silly whine coming out of your HO-scale '38' loco? This steam sound simulator makes arealistic ELEC fRC' } 'chufflng' sound Iha! keeps bLECTRC' ( pace with the loco speed. ELEClRC' i: Kil Includes PC board all specified components and the ELECTRC' ) expensive 82mm loudspeaker. ELECTRC / Cal. KC-5093 := ~t~gi:g • •• AA AR AA :=~t~gi=g • • AR AR ~R ELECTRO ~R ELECTRO ~R ELECTRO ~R ELECTRO \R ELECTRO } ) :i KA-1730 $21 95 :i Rall master Train Controller 29 Re/Sponse SPEAKERS kll Cat. KC-5028 $89. See catalogue for full delalls. Super high power dual impedance 4 and an. ~= ~t~gi=gi •)}'J::::==============:z• : \R ELECTRO! 0 SERIES 11 REAMP KIT $2495 ) 6" 80Wrmsca1. cw-2140 r· SOLAR n• NELS $75 ,R ELECTRO! \R ELECTRO! , rM \R ELECIROI • Brand new range for 1991, al much lower prices - or much \R ELECTRO! : higher watts per dollar. Available soon. \R ELECTRO! • Specifications: \R ELECTRO! : 1watt 4watt 8watt \R ELECTRO! • 13-18V 6-SV 13-18V \R ELECTRO! • Operating V \R ELECTRO! : Operating A 120/160mA 200/280mA 500mA \ R ELECTRO! • *Power W(peak) .75/1.25 2.5/5 8W \R ELECTRO! : 305x610 Size mm 152x152 305x305 \R ELECTRO! : -5o•c to +70°C \R ELECTRO! : Temp Range \R ELECTRO! • *Depends on sunlight intensity. \A ELECTRO! : cat ZM-9020 \R ELECTRO! • IR El f'CTROI : cat ZM-9026 IR ELECTRO! : cat ZM-9030 \R ELECTRO! : \A ELECTHOI : \ R ELEClHOI • \R ELECTHOI : \R EU:CTROI • \R ELECTRO . \R ELECTRO; : IR ELECl R01 • IR ELECTRO! • IR ELEClROI : \R ELECTRO! • \R ELECTRO! : IR ELECTRO! : IA ELECTRO! : IA ELECTRO! : IA ELECTRO! : IR ELECTRO! • IA ELECTRO! , • IR ELECTRO! • IA ELECTRO! • IR ELECTRO! . IA ELECTRO! : IR ELECTRO! • IR ELECTRO! : IA ELECTRO! : IA ELECTRO! \ IA ELECTRO! •:•:•. \R ELECTRO! }}j : 1A ELECTRO! { ( 8" 120Wrms Cat. CW-2142 $109 1 0" 160Wrms Cat. CW-2143 /60 STEREO AMP IT $165 12" 200Wrms Cat. CW-2145 KA-1652 $199 Dome midrange (Bo $24H 1 watt 6V $89H 4 watt 12V $169H 8 watt 12V Cat. C M-2090 69 only) $49" Dome tweeter (so only) Cat. CT-2010 $3250 CR2025 as used In our Dalabank Cat. SB-2520 := ~t~g:g; ,A ,R ,R ,R ELECTROt ELECTRor ELECTR01 ELECTRO! $3.50 ea PC BOARDS VERO STRIP TYPE Alpha numeric grid, pre-drilled 0.9mm, 2.5mm spacing. SOLAR GENERATOR KIT ff \) \( )) )\ () \\ }} :: ~t~g:g: $1395 ) ?1 ,A ELECTRO! ,R ELECTRO! ~~ !~!~l~~i • 1A ,R ,R 1R 1R ,R ,~ ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JAYCAH JAYCAR JAYCAR JAYCAR {{ - ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELEClRONICS We have purchased alarge quanllly of DPDT 1'N 3A high qualily Japanese made Omron PC mount relays. These are Telecom approved, plastic sealed with bifurcated crossbar contacts. They conformlo International 2.54mm terminal pitch and have alife expectancy of 100,000,000 operations. You would expect lo pay around $10 each for these. . _ Specifications: ·- ------= Voltage DC 1'N Current 24mA Resistance soon Contac1Raling3A Cal. SY-4055 :g Jt, JAYCAR JAYCAA JAYCAR JAYCAR JAY CAR JAYCAR ~ ~ ~s;:~~~:s~ ~~~s~~ ~ ~~s;:~~~:~~ ~~~~~~ $2SO $3 79 95 X 303mm Cat. HP-9544 $5 .. 95 X 76mm Cat. HP-9540 )) Ref: ETI December 1987 Acheap, no fuss way lo trickle charge a 12V lead acid/deep cycle or Gel baltel}' from any of the solar panels shown above. The lype of panel used Is nol vel}' critical. Typically no more power than 6 walls is required with an oulpul voltage of 12-18 volts. Short form kit Includes PCB and all components. Cal. KE-4730 := ~t~gi=g: t.. - $3.50 ea CR2032 Cal. SB-2522 :::=::::::::::::::::z::::z::::z::::z::::z::::z::::z::::::::::::::::::s ,R ELECTRO! ..... \R ELl:CTROI . IR ELECTRO! IR 1:LECTROI ,R ELECTRor ,A ELECTRor ,R ELECTROr !~:•Es 1 POWER 12/24V LIGHT CHASER := ~t~g:g I SIMULATOR KIT FOR AR ELECTRO •••• · J::~ ELEClRONICS JA YC AR ELECTRONICS JAY CAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRO~ ELECTRONICS JAYCAR ELEC TRONICS JAYCAR ELEClRONICS JAYCAR ELEClRONICS J AYCAR ELECTRO~ ELECTRONICS JA YCAR ELEC TRONICS JAYCA R ELECTRON ICS JAYCAR ELECTRONICS JAYCAR ELECTRO~ -• - - - - - - -- -- --- -- ELECTRONICS JAYCAR ELEC TR ONICS JAYCAR ELECTRONICc, JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ~~~~!~~ 1 cs JAYCAR 95 X 152mm Cat. HP-9542 9 : :~ ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELEC TRONICS ELECTRONICS ea·_ JAYCAR JAYCAR JA YCAR JAYC AR JAYCAR J AYCAR JAY CAR ELECTRONICS JAYCAR ELECTRONICS JAYCAA ELECTRONI CS JAYCAR ELECTRONICS JAYCAR ELEC TRONICS JAYC AR ELECTRONICS JAYC AR ELECTRONICS JAYCAR ELECTRONI CS ELECTRONIC S ELECTRONIC S ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS JAYCAR JAYCAR JA YCA R JAYCAR JAYCAR JAYC AR JAYCAR ELE CTRONICS ELEC TRONICS ELECTRONIOS ELECTRONICS ELECTRONICS ELEC TRONICS ELECTRONICS - JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR J /\YCAR - ELECTRONICSJAYCAR ELECTRONICS JAYCAR ELECTRONICS JA YCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICSJAYCAR ELEC TRONICS JAYCAR ELECTRON!< ELECTRON!< EtECTRONI! ELECTRONI! ELECTRONl1 ELECTRONI! ELECTRONI! JIC~ J A YC AH t.Lt.L, I HUN IL,~ JAYl,AH t:Lt:l, I HU l~ I V.:::> J AYV /"\ n C L CV 11""\V l,. IV.:> JM TV Mn r.:.LLV I nv1 ,.1 vv ,J,-., 1 ,._, ,....,, 1,...._._,._, , , 1v 1,., ,._,..., ,J,-.,, ,._,,.,,, ._._.._....,,, ,,._,, ~,,_,,_, ..,,, , ....,,., , ._._._._.. , , ..,_, , .,...,..., .., . . . ..... . ... _ _ __ . · - · ··- _ _ i:cs JAYCAR ELEC TR ONICS JAYCAR ELECTRONICS J AYC AR ELECTRONICS JAYCAR ELEC TRONICS JAYCAR ELECTRONICS J AYCAR ELECTRONICS J AYCAR ELECTRONICS JAYCAR ELEC TRONICS JAYCAR JIGS JAYC AR ELECTRONICS JAYCAR ELECTRONICS J AYC AR ELECTRONICS JAYCAR ELEC TRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS J AY CAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR JIGS JAYCAR ELECTRONICS JAYCAR E:Ll:ClRONICS J AYCAR ELECTRONICS JAYCAR ELECTRONICS JAYC AR E ECTR NI S AV AR EL TR NI JA AR ICS ,IAYCAR FI Fr.TR()NICS JAYCAR ICS JAYCAR ICS JAYCAR ICS JAYCAR ICS JAYCAR Considering ihe price, we are most impressed at how well this unit works. II h~s an ABS plastic body wllh strong suction. Unll is ICS JAYCAR .ICS JAYCAR very easily cleaned, corni ng apart In the centre, In moments. Spare lips are available and are very reasonably priced. Tola! ienglh Here's whal you gel: ICS JAYCAR Inc. lip 195mm. • 5 slolled blls 0-1 , 3-4, 5-6, 8-10, 12 ICS JAYCAR Repl acernenl lip (Tetlon;cat. ___ hex bils 3/32', 5/64', 7/64', 1/8', 9/64' ICS JAYCAR TH -1861$2.95 i..._ ICS JAYCAR • 4 Philips bils No. 0, 1, 2 & 3 Cal. TH-1860 ICS JAYCAR • 4 square recess blls No. 0, 1, 2 & 3 ICS JAYCAR • 6 Tor]( bils T10, T20, T25, T30, T40 ICS JAYCAR 05 • 2 Pozldrlve blls No. 1 & 2 ICS JAYCAR • 1 x 1/4 • drive sockel adaptor ICS JAYCAR • 1 x 1/4' dr: 1ehex bll holder ICS JAYCAR ICS JAYCAR And ll's all housed In a sealable lough pl astic case . ICS JAYCAR Cat. T0-2000 · ICS JAYCAR Replaces !hose old desk type calendars. Electronic ICS JAYCAR Calendar/Clock shows • time ICS JAYCAR INCLUDES ~l l OF THESE PIECES: ICS JAYCAR (ellher 12 or 24 hour formal) • c::::::l-q, ~ ~ : ICS JAYCAR Monlh • Day • Dale and Year. ICS JAYCAR Large easy lo read display wilh Incorporates a large 18mm high display for 'CS JAYCAR a back lighl for nigh! viewing ICS JAYCAR temperature from -20°C to +70°C. And a l the and 3 year ballery life, Ideal 'CS JAYCAR tough of a button the time appears . There are for desks, cars, kitchens, etc. CS JAYCAR two temperature sensors - one inside the unit <at> CS JAYCAR Cal. OM-7218 and the other on the end of 3.5 metres of CS JAYCAR 95 cable for reading outside. Flick a switch and it CS JAYCAR will read the temperature instantly for eithert CS JAYCAR CS JAYCAR inside or outside CS JAYCAR Cat. XC-0125 CS JAYCAR CS JAYCAR CS JAYCAR CS JAYCAR CS JAYCAR CS JAYCAR CS JA,YCAR CS JAYCAR CS JAYCAR CS JAYCAR The Maggylarnp Is awidely adjusled CS JAYCAA magnifier wi th a12.7cm diarneier biCS JAYCAA convex lens 4.00 dioptres focal lenglh of CS JAYCAA 25.4cm. II ls essenlially a rnl nlscope wllh CS JAYCAA llghling. Maggylarnp has flexible arms for CS JAYCAA CS JAYCAR easy posilioning. Handsome, slurdy CS JAYCAR conslruclion assures years of service. CS JAYCAF CS JAYCAF Now you can have lhe same beaulilui 'firelly' lighting Iha! Is CS JAYCAF CS JAYCAF all over !he civic squares around Auslralla and overseas. CS JAYCAF Now you can purchase the bulbs In packs ol 10 for only CS JAYCAF Ferguson brand. Supplied cornplele in a sealed case wilh $12.95. Each globe draws only 38rnA al 12 volls so abank 100 assorted LED's Inc. 3 & 5mm In yellow, orange, red & CS JAYCAF a fuse and mains lead/plug. Two pin US style socket of 20 globes draws only 760rnA, which enables you lo use green. Rectangular, triangular and others. All for less lhan 9t CS JAYCAF mounted on case. Will deliver up lo 1.74 amps or 200 ea1 an Inexpensive 2155 transformer Cal. MM-2002 $10.95. CS JAYCAF 95 walls. '.; S JAYCAF Use your own speaker llex type cable and save even more! C~I. ZD-1696 Cat. MF-1094 CS JAYCAF All you require is Fig 8 speaker or mains cablelo use lhese CS JAYCAF bulbs. CS JAYCAF cable (speaker) to suit Cat. WB-1708 55t per rnelre CS JAYCAF Power supply 1 amp ·transformer - up lo 25 globes Cat. CS JAYCAF CS JAYCAF MM-2002 $10.95 CS JAYCAF 2 amp transformer - up lo SO globes Cal. MM-2004 $16.95 CS JAYCAF Cal. SL-2800 CS JAYCAF CS JAYCAF CS JAYCAF CS JAYCAF 3.5 digit man'.Jai or auto range with logic probe and data hold. See catalogue for full details. CS JAYCAF Cat. OM-1420 ;s JAYCAF ;s JAYCAF ;s JAYCAF ;s JAYCAF ;s JAYCAF ;s JAYCAF ;s JAYCAF ;s JAYCAR ;s J AYCAF ;s JAYCAR ;s JAYCAR :s JAYCAR :S JAYCAR :s JAYCAR :5 JAYCAR :s JAYCAR We have a lirnlled quanllly ol lhese quality chargers available. They are Nol only is II a5 way power board, it tncorporales a voltage :s J AYCAR 240Voperaled with an oulpul of 14.2V al 1.6A rnax. II ls an Intelligent ·s JAYCAR surge and spike protector and noise rejection filler network. charger, which means Iha! when !he ballery Is charged !he uni! will .s JAYCAR Supplied wilh lwo metre cord and mains plug, safely shuller auiornali cally swilch itself lo trickle charge saving damage lo lhe ballery ,S JAYCAR on each outiei, illurnlnaled rnasler on/oil and even a safely and charger. Mos I Gel chargers don'! have ihis lealure. :s JAYCAR circuit breaker. '', JAYCAR II will charge our 6.SAh batleries In about 10 hours and our 15Ah cells In 95 ~AR Cal. MS-4030 about 20 hours. Oulpul lead lo ballery Is a3 pin Cannon type which In S JAYCAR mosl cases wi ll need lo be removed. Mains lead length 2 rnelrn~ . oulpul 30 PIECE ENGINEER'S DRIVER SET ECONOMY DESO'LDER PUMP •s NORMALLY $9"SAVE $3 APRIL ONLY $6 SAVE $5 ONLY $14.95 0 .., , , . , . . . , . .~ - • • • CALENDAR/CLOCK INSIDE/OUTSIDE DIGITAL T HERMOMETER CLOCK c::::::g CD i.~ ~ ~ ~ EB c:::::i:=; ~ ~ ~ ~ ~ ~ ~ i . .~ $19 $ 2495 TECHLITE BULBS · LOW VOLTAG E LIGHTING SYSTEM 240V-115V 200VA Stepdown Transformer $8 $189 50 $1295 $ 5 995 &WAY POWER OUTLET WITH MAINS FILTER $49 TELLIGENT GEL BATTERY CHARG •t®f1J•I - _v~AR lead lenglh 1.8 rnelres. Size 175(L) x 1IS(W) x 60(H)rnrn. Cal. MB-3507 SM APPROVED AN ABSOLUTE BARGAIN AT $69.95 JIGS JIGS JIGS JIGS JIGS JIGS JIGS - J AYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS --- - ~ JAYCAR JAYCAR JAYCAR JAYCAR J AYC AR JAYCAR JAYC AR ---- - L-~ - ELEC TRONICS ELECTRONICS ELEC TR ONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONI CS JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYC AR ELECTRONICS JAY CAR ELECTRONICS JAYCA R ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ,,.,..,_,..-L..a..i.L.0,. .0 ~ 1 , _ J . . I . C C . ELECTRONICS ELECTRONICS ELECTRONICS ELE CTRONICS ELE CTRONI CS ELECTRONICS ELECTRONICS JAYCAR JAY CAR JAYC AR JAYCAR JAY CAR JAYCAR JAYC AR • ~ . t . . . . . r r--rn <""'!.l.u r- c, J/\\.' C'- f\ O ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS C l crT Of"\ '1..111"' ~ JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR ELECTRONIC~ ELEC TRONICS ELECTRONICS ELEC TRONICS ELECTRONICS ELEC TRONICS ELECTRONICS CL£C.I.Q.Qt.Jlrc.;_ JAYL: AH JAYCAR JAYC AR J AYCAR J AYC AR J AYC AR JAYCAR l: LI:<.: I KUNI<.::; ELECTRONICS ELECTRO,"C5 ELECTRONICS ELECTRONICS ELEC TRONICS ELECTRONICS J AY<.:AH JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR - .. ,CAR ' S JAYCAR S JAYCAR S JAYCAR S JAYCAR S JAYCAR S JAYCAR t:LI:<.: I HUNICS JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELEC TRONICS J AYCAR ELECTRONICSJAYCAR L.6.Yr..6.R.. EL !=r.TRnN1r.s_. lAYr.AR FI Fr.TRONlCS.......LAY(;AR -- - . - · · · - - -· • - · - - - - .. · - · · · ........- • ,...,.,,., ......... ..., , ,,..., , . , ...,,...,.in rvr, 11 LLL V ln\.Jl'IIV->.JMJV,-Ul LLLVln\.Jl'IIV~ lVMn LL L VlnVl'IIV.::;Jl"'\ T Vl"\n C L CV I NV 1YCAR ELECTHONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRO IYCAR ELECTHONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRO \YCAR ELECTHONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRO \YCAR ELEC; IYCAR ELECT IYCAR ELECT IYCAR ELECT IYCAR ELECT IYCAR ELECT Anigh quality case and Included is hardware to mount 2 x 3.5 1YCAR ELECT floppy drives and a hard disk. Rear panel is provided for typical IYCAR ELECT AT communicallons Including • modem • parallel port• This keypad Is 1YCAR ELECT designed lo be mounted near printer • keyboard, etc. Front panel has flush mount 'turbo' and 1YCAR ELECT your exlVenlry point allowing reset switches along with 2 digit LED display to show CPU 1YCAR ELECT. clock speed. Measures 41 O(WE) x 90(H) x 395(0). Power your alarm panel lo be hidden. 1YCAR ELECT supply provides +5V<at> 15A +12V<at> 5.6A, -5V<at> 0.5A, The keypad Is mounted on a 1YCAR ELECT ,YCAR ELECT 12V<at>0.5A brushed stainless steel ,YCAR ELECT mounllng plate. Ideal lo use Cal.XC-5084 ,YCAR ELECT with all our alarms panels. 1YCAR ELECT See catalogue ,YCAR ELECT for full details and ,YCAR ELECT 50 specifications. Cal. LA-5160 NCAR ELECT ,YCAR ELECT ,YCAR ELECT ,YCAR ELECT Two different modules are available. Both chime the hour Our economy besl ,YCAR ELECT after playing lhier selling PIR lhal works ,YCAR ELECT tune. extremely well and Is ,YCAR ELECT XC-0106 plays the ultra reliable. It's so ,YCAR ELECT Features: Westminster Chimes reliable that we have ,YCAR ELECT • Erase up lo 9 chips at a lime each hour then gongs ,YCAR ELECT Increased the warranty • Chip drawer has conducllve loam pad the hour (I.e. 7pm - 7 .YCAR ELECT pe~od lo one year. This • Mains powered gongs). ,YCAR ELECT unit sold for $109 In • High UV Intensity at chip surface ensures thorough erase ,YCAR ELECT XC-0107 plays a 1988. See catalogue for .YCAR ELECT • Engineered lo prevent UV exposure different melody each lull details ,YCAR ELECT • Long UV lube life hour, then gongs the Cal. LA-5017 .YCAR ELECT 50 hour. Both units are Cal. XE-4950 .YCAR ELECT supplied with: llleplac_,.nt tube Cat. XE-41151 $19.95 .YCAR ELECT • Clock movement .YCAR ELECT .YCAR ELECT • Speaker and battery YCAR ELECT holder (3 xAA balleries required) YCAR ELECT • 3 sets of hands YCAR ELECT Westminster Chimes Cal. XC-0106 YCAR ELECT 12 Melodies Cal. XC-0107 YCAR ELECT 115 YCAR ELECT YCAR ELECT. YCAR ELECT Bands: FM-88/108MHz • AM-630/1600kHz • LWYCAR ELECT 150/280kHz • SW1 (49M) 5.85/6.20MHz • SW2 (41 M) YCAR ELECT 7.10/7.50MHz • SW3 (31M) 9.45/9.90MHz • SW4 (25M) YCAR ELECT YCAR ELECT 11.50/11.95MHz • SWS (19M) 15.10/15.55MHz • SW6 YCAR ELECT (15M) 17.45/18.00MHz. YCAR ELECT Listen to the world. II features 9 bands, LED tuning Indicator, YCAR ELECT 3' speaker, fN DC external power Jack, earphone Jack, tone YCAR ELECT New range for 1991. Now made by the manufacturers of switch. Requires 4 x AA cells. To operate on 240V mains use YCAR ELECT Re/Sponse drivers. See 1991 catalogue for lull details. our Cat MP-3005 $15.95. YCAR ELECT 50 YCAR ELECT Cal. AR-2200 10" 65Wnns Cal. CG-2376 Ref: SIiicon Chip Sept 1990 YCAR ELECT 115 50 YCAR ELECT Remote control your VCR from another room. Complete kll 12" 100Wrms cat CG-2380 YCAR ELECT 115 Cal. KC-5084 YCAR ELECT 12" 200Wnns Cal. CG-2381 YCAR ELECT YCAR ELECT 15" 150Wrms Cal. CG-2382 YCAR ELECT YCAR ELECT YCAR ELECT YCAR ELECl YCAR ELECT YCAR ELECT YCAR ELECT YCAR ELECT YCAR ELECT YCAR ELECT YCAR ELECT YCAR ELECT YCAR ELECl YCAR ELECT YCAR ELECl YCAR ELECT YCAR ELECl • Frequency YCAR ELECT • 4000counl • Transistor lest YCAR ELECT • 39 range YCAR ELECT • Capacitance • Inductance YCAR ELECl ' • Data hold • Capacitance YCAR ELECl , • 20 amp current • frequency YCAR ELECl Cal. OM-1560 • Temperature YCAR ELECl • Peak Hold YCAR ELECl • Logic YCAR ELECl YCAR ELECl Cal. OM-1475 YCAR ELECl YCAR ELECl YCAR ELECT YCAR ELECl YCAR ELECl YCAR ELFCl YCAR [LECl YCAR ELECT YCAR ELECl (CAn ELECTI AC Slide in style AT case including 150W power supply Digital Access Keypad Brand new model Don't pay $279 ONLY $169 MELODY CLOCK MOVEMENTS $69 Passive Infra Red Detector Ultraviolet EPROM $1 09 $59" 9 MULTIBAND RADIO • 9 BAND ea MUSICAL INSTRUMENT SPEAKERS $49 $99 $1 59 $1 29 REMOTE CONTROL EXTENDER KIT FOR VCR'S $59 $29 $189 - $169 - WWB~=~;::;:;i:=i::i:::;:::::::;;::;:;:;;::!$;!:2b::::::::;:::::::;:: . ... (CAR EL[CT , ,....,, ,., vVVM I V/"'\f"l LLLV l rlVl'I IV~IVr\11 LLLV I I\Vl'IIVVV(""\IVr\11 LLL,._,,,,...,,. , ...,......,,,, ...,, ... ... ':-.__. , , , ...,.,u..,<uv< ,,...,. " ' ........__., ,, .... ,. ,...,..,...,.. ,,...,, " ' ......... ,., . . , .... . . . ......... ~,,, ...,,.,, ._._ ._ ..., , , , ...,,,. , -.J\JUf\ l ...,,., , ... ._.__ (CAR (CAR (CAR (CAR (CAR ELECT RONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR EL[ CT RONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR 'CAA F I CCT RONICS. JAYCAB El ECI RONICSIAYGAR El FCI BONI.CSJAYCARELECillOMCSJAYCARELFCIOONICSIAYCA R FI FCTROt-llCS /A YC AP ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELEtTRONICS FI .·Re JAY CAR ELECTRONICSJAYCAR ELECTRC JAYCAR ELECTRONICSJAYCAR ELECTRO JAYCAR ELECTRONICSJAYCAR ELECTRO JAYCAR ELECTRONICSJAYCAR ELECTRO JAYCAR ELECTRONICSJAYCAR ELECTRO FCT.cn.till.C..(j;:.JAVCAD C l C CTOO III C C I AVC AO C! C CTDO NIL,~ JAT L,AH t:Lt:L, I HUl\il l L,.)..JAT VAti t:LCVlt\Ul\ill\..,.::,..»-\ J \..,l"\t, CLC:V I nVl \ill\..,.:)ul-\ l\JJ-\n CLCV I NUl'lillV..:> .JI-\ J\JM.n L:.LLV I nvi-.1V-.>.Jr\l '-''"'" LLLV' 111v1111 ..... ......n, ......, " I ._ ............. , , , ..... ,~, ..... <vv,' ' ...,, " • ... ............ • • · -· ··-·,.... .. ...., " , - - NICS JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONIC(:JAYCAR ELI NICS JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONIC(;JAYCAR ELI NICS 1Avr.AR FI FCTROIIIICSJAYCAR ELECTRONICSJAYCAR FI FCTRONICS.IAVCAR FI FCTRONIC'-<; .IAVCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONIC(;JAYCAR ELI JAYCAR ELI JAYCAR ELI iJAYCAR ELI JAYCAR ELI f: SIiicon Chip Nov 1989 JAYCAR ELI you have an IBM or PC compatl bi JAYCAR ELI Ref: EA August 1986 YCAR ELI wave radio you can plug Into the lnt YCAR ELI SCARE THE PANTS OF WOULD BE THIEVES! This car alarm transmissions on the shortwave ban Ref: SIiicon Chip Oct 1988 YCAR ELI Is filled under the dash of the car. When athief breaks In (after from the author (details supplied wit INCREDIBLY POPULAR STEREO KIT! YCAR ELI entry delay) an unbelievably loud shrill sound goes off front panel, box a You can connect your CD player (or record player) to the JAYCAR ELI INSIDE THE CAR making II too unbearable to proceed with Cat. KC-5059 Mini-Mitter and then listen anywhere In the house, via your JAYCAR ELI stealing the car. The alarm has adash tamp flasher and entry 19 YCAR ELI Walkman personal portable. Also Ideal for playing CD's In delays, a three second soft alarm to remind you to turn II off, YCAR ELI your car -via your portable CD player and your car and automatic resetting. Two Inputs are provided. The Jaycar JAYCAR ELI stereo/radio. The Mini-Mitter puts out 200 mlcrowatts. The JAYCAR ELI kit Includes the direct Import 116dB screecher, dash lamp, Jaycar kit Includes PCB, case, front panel and all JAYCAR ELI PCB and all components. components parts. Beware of Inferior kits. JAYCAR ELI Cat. KA-1675 Cat. KC-5041 JAYCAR ELI 50 115 JAYCAR ELI JAYCAR ELI JAYCAR ELI JAYCAR ELI JAYCAR E:LI JAYCAR ELI JAYCAR ELI JAYCAR ELI JAYCAR ELI JAYCAR ELI .JAYCAR ELI JAYCAR ELI JAYCAR ELI JAYCAR ELI Ref: SIiicon Chip Jan 1991 .;;(YCAR ELI Have fun al home with 1JAYCAR ELI our new fruit poker Ref: SIiicon Chip Aug 1990 JAYCAR ELI machine kit. There are .JAYCAR ELI This new kit uses high speed CMOS four symbols on the .JAYCAR E:LI ICs lo produce sine and square wave .JAYCAR ELI reels. Afor aces, 0 for over the frequency range from 0.1 Hz .JAYCAR ELI oranges, Cfor cherries, SOOkHz. II features excellent JAYCAR ELI and L for Lemons. The specifications with a4 digl) JAYCAR ELI project Includes a frequency read-out and an output JAYCAR EU speaker to give you level control. This new kit Includes JAYCAR EU audible click-clicks like a JAYCAR EL PCB, box, punched and screened real poker machine and JAYCAR EL front panel and all specified componen JAYCAR EL the reels even slop one Cal. KC-5079 JAYCAR EL after the over. 90 JAYCAR EL The kit ls basically a JAYCAR EL short form one. It JAYCAR EL Includes PCB and all specified components. Wooden box JAYCAR EL and plugpack are not supplied. Plugpack use Cal. MP-3006 JAYCAR EL JAYCAR EL $15.95. JAYCAR EL Cal. KC-5039 JAYCAR [L Ref: ETI Dec 1985 JAYCAREL This unit ls a two transistor two stage transmitter that has the JAYCAREL benefits of being VERY COMPACT. The Jaycar kll contains all Up to 30% cheaper than other suppliers. Grilles pressed out JAYCAREL specified parts and makes an Ideal, Inexpensive beginners kit. of strong, perforated steel to protect HI FI or PA speakers In JAYCAR EL Cal. KE-4711 cabinets or cars, etc. Each grille has a rubber edge band and JAYCAREL black painted finish. Grille Is supplied with 4 mounting lugs, JAYCAR EL JAYCAREL heavy duty screws and T-nuls (cabinet fixing spiked nuts.) :JAYCAR EL 115 Cal. AX-3520 for 8' speakers JAYCAR EL Ref: SIiicon Chip May/June 1988 115 .JAYCAR EL Cal. AX-3522 for 10' speakers This Ignition gives extra high energy - essential for todays .JAYCAR EL 95 high rewlng lean air/fuel ratio Ignitions. .JAYCAR EL Cal. AX-3524 for12' speakers JAYCAR EL • Slightly extra power 15 Cal. AX-3526 for 15' speakers ;JAYCAR l:L • Slightly better fuel economy .JAYCAR EL • Much better weVdry starting .JAYCAR EL • Much greater time between tune-ups ;JAYCAR EL The Jaycar kit Includes all o al specified co ;JAYCAR EL Including die cast box, et ;JAYCAR EL {:H'-t-f.;z-/,.::r:f,;l:;JAYCAR EL Cal. KC-5030 ;JAYCAR El ' ..JAYCAR ELI :;JAYCAR EL Protection for: microprocessors, terminals, micro computers, ;JAYCAR ELI printers, disk drives and telemetry equipment. Used by ;JAYCAR ELI government departments, schools, unlversllles, banks and TV ;JAYCAR ELI stations. .JAYCAR ELI JAYCAR ELI 2 OUTLET Cal. MS-4025 JAYCAR ELI JAYCAR ELI JAYCAR ELI JAYCAR ELI JAYCAR ELI JAYCAR ELI Yes, that's correct. High quality Benelec brand 0.65mm JAYCAR ELI conductor, airspace PE dielectric, foll shield, 5mm OD JAYCARELI Jaycar will purchase your surplus stocks of sheath, broon In colour air space, 750 coax. Save a •JAYCARELI components and equipment. We are fortune over normal prices. 1oi metre for quantities less JAYCAR ELI continually on the lookout for sources of than 100 metre roll. JAYCAR ELI prime quality merchandise. Cal. WB-2002 JAYCAR ELI CALL MARK HARRIS OR JAYCAR ELI JAYCAR ELI BRUCE ROUTLEY NOW ON JAYCAR ELI (02) 747 2022 JAYCAR ELI "SCREECHER" CAR ALARM MINI-MITTER · FM STEREO T ANSMITTER KIT $44 $37 $34 149 MINIATURE FM TRANSMITTER KIT $26115 HIGH ENERGY TRANSISTOR ASSISTED IGNITION KIT METAL SPEAKER CONE PROTECTOR GRILLES $9" $1 0 $1 2 $14 $1 7 A~-.. SQU EEKY CLEAN DOUBLE OUTLET MAINS FILTE $55 $1 09 750 COAX BARGAIN AIR SPACED COAX AT $35 100m ROLL TURN YOUR SURPLUS STOCK INTO CASH!! $35 - 100 metre roll $ ~NICll~!!li!l!!!l'!!!!l!l!'!!!!!l!!!!IIJ!!ll!!!'!l!'ll!!'!"!!!!l'!!!!llll"'-'11!!!!!!111!!!1!!!!11!!11!!1!!'~~~~;,;,;:;;;;;;;;::;;:;;;,;::;:;,;:;;;;;;:;:;;:;;:;;:;;:;f; NIC~ 'T\jf\ t:L t:\., 1HVN1 \J ~l-\1\Jl'\t1 t:LtVlttV t-.1\..,.::,,.,,,-\ T\JM. n ~ NICSJAYCAR ELECTRONICSJAYCAR NICSJAYCAR ELECTRONICSJAYCAR NICSJAYCAR ELECTRONICSJAYCAR NICSJAYCAR ELECTRONICSJAYCAR NICSJAYCAR ELECTRONICSJAYCAR FI ECTRONICSJ.tiYCAR ELECTRONICSJAYCAR ELECTRONICS.JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR LL.Lv 1nu1\II V ,.;,-.,, 1v1"1n L..Ll '-'' v1'il1vv.1r 1 111 ELECTRONICSJAYCAR [LECTRONICSJAYCAR ELECTRONICS JAYCAR ELECTRONICS.JAYCAR El ECTRONICSJAYCAR ELECTRONICS JAY CAR ELECTRONICS.JAYCAR ELECTRONICSJAYCAR ELECTRONICS JAY CAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR _L<-'- ,, ...., • • ,'"'.......,., • ...,, ... ., ELECTRONICSJAYCAR f:LECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR [l ECTRONICSJAYCAR :::::;:;;;;;:;;;,;:;;;,:;;;:;;;;;;:;;;;;;;;;;;;;,;;:;;;;:;;;;:;:;;;:;;;:WJSJAYCAR El ,_ ,., ...,&JAYCAl1 El -1 ...A_, • • .,.,.., • • • ...,...,..,, , , . . . , , . , , , , • ...,..,,,, ...,, ., , rt FCTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ---~~ - •• f:LECTRONICSJAYCAR ELECTRONICS.JA YCAR ELECTRONICS.JA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR " Iler , .,\tcA □ n c ,..Tno., ucc 1Avc AP P c c ro01>. 11,..s !AYCAP r:1 FCTPOMICS IAYCAR FI FCIRQMrt: IAVrAR 1=1 F"CTAQN1r.s1Avr.AA F"I Fr.TAONI.CSJAYC"J\flELFCIRONICS l.t\YCAR FI FCTRONlCSJAYCAR El El El El El Fl '\M t:Lt:L. 1 MVNIL,;:, J AY L,AM t: Lt: V I M U Nl!vb JAYL,AH t:. L t:.L,; 1 H UNIL b JA Y LA H t: Lt:.L I HUN ll; :::i J AYCAH !:::Ll::C I HUN IC ::i JAYCA H 1::. Ll::.C I HONIC::i JAYCAR E LEC T RON ICS JA Y CAR ELECTRO NI CS JAYCA A E LEC TRO' ~R ELECTRONICS J AYCAR ELECTRONICS JAYCAR ELECTRONICS J AYCAR ELECTRONICS J AYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELE CTRONICS JAYCA R ELECTRO/ ~R ELECT yr. F .T I S y AR ELECTRONICS J AYC AR ELECTRONICS JAYCAR ELECTP.ONICS JAYCAR ELE CTRONICS JAYCAR ELECTRONICS JA YCAR ELECTRONICS JA~~A~ §L§g= g ~R ELECTI IR ELECTI IR ELECTI IR ELECTI \R ELECTI \R ELECTI IR ELECTI IR ELECTI \R ELECTI IR ELECTI \R ELECTI I R ELECTI \R ELECTI I R ELECTI \R ELEC TI IR ELECTI \R ELECTI \R ELECTI IR ELECTI IR ELECTI \R ELECTI IR ELEC TI IR ELECTI IR ELEC TI IR ELEC TI IR ELECTI IR ELECTI IR ELECTI IR ELECTI 1R ELECTI 1R ELECTI IR ELECTF IR ELECTf IR ELEC TF IR ELECTI IR ELEC TF IR ELECTI IR ELEC TI IR ELEC TI I R ELECTI \R ELECTI IR ELECTF 1R ELEC TI IR ELECTI 1R ELECTF IR ELECTF IR ELECTI 1R ELEC TI 1R ELECTI 1R ELECTI IR ELECTI IR ELECTI \R ELE.CTI IR ELECTI 1R ELECTI IR ELECTI IR ELECTI IR ELECTI IR ELE CTf IR ELECTI 1R ELECTF ,R ELECTf ,R ELECTf ,R ELECTf ,R ELECTF ,R ELECTF ,R ELECTf ,R ELECTF ,R ELECTF ,R ELEC TF ,R ELEC TF ,R ELEC TF ,R ELEC TF ,R ELECTF .R ELECTF .R ELECTF .R ELECTF .R ELECTF .R ELECTF R ELECTF R ELECTF R ELEC TF R ELEC TF R ELEC TF R ELEC TF R ELECTF R ELEC TF R ELECTF R ELECTF R ELECTF R ELEC TF R ELECTF R ELECTF R ELECTF R ELECTF R ELECTF R ELECTF R ELECTF R ELECTF R ELECTF R ELECTF R ELECTF R ELECTF R ELECTF R ELECTF R ELECTF R ELECTF Hung Chang 20MHz Dual Trace Oscilloscone UHF Wireless Burglar Alarm • Wide bandwidth and' high se nsitivity • Intern al grati c ule rectangul ar bright CRT • Built-in component tester • Front panel trace rotator • TV video sync filter • Z ax is (intensity modulation) • Hi gh sensitivity X-Y mode • Very low power consumption • Regulated power supply c ircui t Cat. OC-1 900 Probes to sui t OC- 1902 $39 .50 ea Was ->0,v . ---# · ~ > •~ . ·. · High quality Zeus brand direc t imported by Jaycar. Why wait until after you have been robbed to in stall the alarm . See catalogue for complete details. Comp lete system inc ludes ..... ----·- ----1 x Control Panel 1 x Pass ive Infra Red Detec tor/TX -.,.. :if, $ . • ,,,.. 1 x DoorM'i ndow Reed <i'· ..,... Detector/TX ~ -;..<;< """' 1 x Horn Speaker - 10 ""i .'k ~-"'I,> ~' ••~!'?> watVwired *"--"'" ~ 1 x 240V AC adaptor -,.,,.; 1 x 1.2Ah Back-up Battery **.,...<ii:· , ,;,:><<,:< """" 1 x Set of batteri es for all TX Cat. LA-5200 Spare PIR's, remotes available '' ONLY $599 SAVE $50 over other suppliers ACT DISKS AT EVEN LOWER PRICES CHEAPEST IN AUSTRALIA? onomy Multimet ew model for s packed with lea eeded by a disc j 1 mic input• 4 ste ach input • VU me 40V mains operat ee catalogue for f 17 range DMM at a price that must be the lowest in Australia. Who wou ld have thought you could buy a quali ty OM for under $35 ! Compact size which is ideal for tool boxes , glove compartm en ts, etc. Uses a 9V 216 type battery for long life (100 hours). FEATURES • 3.5 digit LCD d • 3 range battery check • Diode test • Compact size 116(L) x • Easy re-calibration inst t.OM-1 430 at is 5.25" DSDD 5.25" DSHD r 3.5" DSDD $28.95 Cat. XC-4721 3.5" DSHD $57.50 Cat. XC-4722 5.25" DSDD $21.95 Cat. XC-4726 5.25" DSHD $29.95 Cat. XC-4727 Prices for boxes of 1O disks - R ELEC TF',...., ,,,.,,._, ._, vn., '-''"' ', LLL'-' ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS ELECTRONICS J AYC AR JAYC AR JAYC AR JAYCAR JAYC AR J AYC AR R ELECTRO ICS IAYCAA...F I FCTAOflJI CS IA YCAO JAYCAR JAYCAR JAYC AR JAYCAR JAYC AR JAYCAR XC-4738 $3.95 Hiah Efficiency Electric Fence This tfectric Fence has a high output and will energise up to 20km of live wire. It is a "short form" uni t whic h consists of a fu lly assembled and tested PC board. No box or hardware is supplied. SPECIFICATIONS Input Voltage 9-15V DC Input Current <at> 12V 140- 170mA Output Energy<at> 12V 1.0 Joules Pulse Rate<at> 12V 40-45 pul ses per minute Output Voltage<at> 12V No load 6,500V 2,5000 6,200V 5000 5,000V 2000 3,200V 10002,ooov .9 1 WAS $46.95 $99 .00 $26.00 w e N Wire Length Bat Life with 100Ah Battery Cat. ME-6010 R ELECTRONICS R ELECTRONICS R ELECTRONIC S R ELECTRO NICS R ELECTRONICS R ELECTRONICS XC-4732 XC-4736 If you are new to Electric Fences, you will need this manual. It has 12 pages full of very helpful hints and suggestio ns relatin g to fence des igns and sys tems, types of energise rs, fencing wire, gateway and creeks , batteries , so lar panels, cut out switches, insu lation, horse paddocks and faul t fin din g. Cat. BE-8300 NOW Cat XC-4730 ELECTRIC FENCE MANUAL $3 CHEAPEST IN AUSTRALIA? 1990 Price $9.50 $15.95 $15.95 $34.95 20km 26 days fO fl $139.50 i RV i;,iii..,~ .J M 1 'i.., M n cL. c:. v I nvr,m.., u .JMT v Mn C L CV I M U l'llV.:> .JAYVAM t:L.t:.V I MV l'l il..;:, JAYVAH t:.Lt:L, I HvNiL.;:, JAY(.;AH ELECTRONICS ELECTRONICS ELE CTRONICS ELECTRONICS ELECTRONICS ELECTRONICS Cl C C TP Olt. llCC' JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR J AYCAR ELEC TRONICS ELECTRONICS ELEC TRONICS ELECTRONICS ELECTRONICS ELECTRONICS 16\! C IO C l Cl""' T D.0 ,11 00 JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR JAYCAR •• n n ELECTRONICS ELECTRON ICS ELECTRONICS ELECTRONICS ELECTRONIC S ELECTRONICS c- ,,.,,.. 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This 12V light chaser has four separate channels, variable chase rate, fuse protection and uses just two ICs. By DARREN YATES Light chasers using light-emitting diodes (LEDs) or low voltage light bulbs have been around for ages. You don't have to look far for examples. If you go down to your local video store, chances are you'll see a line of flashing lights in the window. Believe it or not, our august publisher recently travelled in a "stretch-limo" which had little LED chasers running down the interior of the car. We wanted something a bit more potent than a LED chaser, so we designed this circuit to drive 12V light bulbs. There are four channels and each channel can handle up to 36W with only a modest amount of heatsinking. A single rotary control lets you vary the chase rate from about one flash every two seconds to four flashes per second. To make the circuit as versatile as possible, we also designed it to run from a 12V to 24V DC supply. This means that you can power it from the mains via a 12V DC plugpack supply, or you can use a 12V or 24V battery if no mains supply is available. A small PC board holds all the parts except for the external pot. If you don't need to vary the flash rate, the pot can be replaced by a fixed value resistor. So, if you want to jazz up the interior of your purple Monaro or panel van, this circuit is the one to go for. For 12V supplies, we recommend that you use the MES (miniature Edison screw) lamps which are rated at 3W. This means that you can use 12 lamps per channel, or a total of 48 lamps for the entire chaser. How it works If you look at the circuit diagram of Fig.1, you'll see that there are only a handful of components to the 12/24V Light Chaser. In fact, the circuit is based on two very common ICs - a 555 timer and a 4017 CMOS decade counter. Let's see how it works. ICl is the 555 timer and is connected as a simple variable frequency oscillator. Its output frequency is determined by the l0kQ and 1.8kQ fixed resistors, the lO0kQ potentiometer (VRl) and the l0µF electrolytic capacitor. The lO0kQ pot varies the frequency from about 0.5Hz to 4Hz. The output at pin 3 is a pulse waveform which is fed directly into the clock input (pin 14) of IC2 , a 4017 CMOS decade counter. On each rising edge of the incom ing clock pulses, one of 10 outputs of IC2 goes high in turn, starting at pin 3. Since we only need the first four outputs and not all 10, we connected output 4 (which is actually the fifth output since we count from zero) to the reset input. When this output goes high, it resets the chip and the first output at pin 3 goes high again. There is a finite delay as output 4 resets the IC but because we are operating at such a low frequency, it is almost instantaneous in effect. So the sequence of events is this: at switch on, the Q0 output (pin 3) is high. When the next clock pulse from ICl arrives, Q0 switches low and Ql switches high. At the next clock pulse, Ql switches low again and Q2 APRIL 1991 53 F1 5A 100U 10 + 16VWJ 16 IC1 555 14 i : : - - - - -""1 CLK 36W MAX IC2 4017 Fig.1: the circuit is based on two low-cost ICs. ICl is a 555 timer wired as an astable oscillator. This clocks decade counter IC2 which switches its outputs high in succession. These outputs then drive transistors Q1-Q4 to switch the lamps on and off. ~ 021"4_ _ _ _~2..,.2k~-------"if-1 15 RST 04 B0649 QJ;l'-7_ _ _ _ _ _..._2Y,.2k,.__ _ _ _ _---"t-t. BCE 13 ~ 12V/24V LIGHT CHASER switches high and so on until Q4 switches high and resets IC2. In other words, the transistors act like switches which are opened and closed one at a time in sequence. Each output ofIC2, at pins 3, 2, 4 & 7, is fed to the base of an NPN Darlington transistor (Ql-Q4) via a 2.2kQ resistor which limits the base current to about 3.5mA. Thus, as each output of IC2 goes high in turn , the corresponding Darlington transistor turns on and switches on the lamp(s) in its collector circuit. The Darlington transistors are TO TO BD649s. These can dissipate up to 60W with suitable heatsinking and also have a gain of at least 750 (but typically above 1000). This means that our 3.5mA of base current is turned into about 3A of collector current running through each transistor. However, since only one transistor is on at any one time, 3 amps is the maximum current drain of the circuit, so the load on a car battery is minimal. To protect the ICs from the spikes and surges that occur in most car electrical systems , we've included a 12V LAMPS-Fi-. q_ 8 E C~~ 100~1 N ~ ZD1 (t~ s1:c::;~SIS TO TO E C~ ~ N ' k IC2 Fig.2: follow this layout diagram carefully when installing the parts on the PC board. Fig.1 shows the pinouts for the four power transistors (Q1-Q4). The lOOQ resistor should be changed to lkQ 0.5W if a 24V supply is used. 54 SILICON CHIP zener diode across the supply line. This also regulates the supply rail to the ICs to +12V if a DC supply of greater than 12V is used. Added protection is provided by the 5 amp fuse which fits directly on the PC board. The circuit also has protection against reverse connection of the battery supply, although it may not be apparent. Each of the Darlington transistors incorporates a reverse-connected diode from collector to emitter and these will conduct if the supply is reversed, turning on all the lamps and (possibly) blowing the fuse. The two ICs are also protected against reversed supply by the 12V zener diode which acts as a forward biased diode if the supply polarity is wrong. Construction The 12V Light Chaser is built on a small PC board coded SC08106911 and measuring 105 x 67mm. Whether you buy or make the board, check that there are no shorts or breaks in the tracks. If you find any, use a small knife to scrape away the excess copper or a dash of solder to bridge the gap a~ required. Fig.2 shows the parts layout on the PC board. Begin by installing 12 PC stakes at the external wiring points, then solder in the wire links and the two fuse clips. Make sure that the fuse clips are M205 versions. These are smaller than the standard 3AG types. Next, install the resistors. Table 1 shows the resistor colour codes or better still, use your multimeter to check the values. Note that the 100Q resistor will have to be changed to lkQ 0.5W for 24V operation. The three capacitors can now be installed. Check the polarity of the two electrolytics carefully (they both face in the same direction). Now for the semiconductors: install the two ICs and the zener diode as shown in Fig.2, then mount the four power transistors (Ql-Q4). Check Fig.1 for the transistor pin connections. When they are installed on the board, their metal tabs should face the centre. The 100kQ pot is connected externally as shown on the wiring diagram. It can be replaced by a fixed value resistor if you don't need to vary the flash rate. If you like, you can mount the completed assembly inside a folded aluminium case. Each transistor should be fitted with a small TO-220 clip-on heatsink for loads greater than 12W. Make sure that the heatsinks don't short together. It's up to you how you wire up the lamps. If you are using the MES (miniature Edison screw) lamps, then matching MES sockets are probably the most convenient. However, these sockets cost as much as the lamps themselves and 48 at around 50 cents each is getting a bit expensive. As an alternative, you might also consider using 12V mini lamps which come with 10mm leads. These are more expensive than the MES lamps but may be more suitable for some applications. Make sure that the lamps are correctly rated for the voltage you are using. If you are using a 12V supply, then you can wire groups of 12V lamps in parallel. If a 24 V supply is to be used, you can still use 12V lamps but these should be wired in series pairs of two, with each pair then wired in parallel. PARTS LIST 1 PC board, code SC081 06911 , 105 x 67mm 10 PC pins 2 M205 PCB fuse clips 4 TO-220 clip-on heatsinks 1 aluminium box to suit 1 100kQ potentiometer (VR1) Semiconductors 1 NE555 timer (IC1) 1 4017 CMOS decade cou nter (IC2) 4 B0649 NPN Darlington transistors (01-04) 1 12V 1W zener diode (ZD1) Capacitors 2 10µF 16VW electrolytics 1 0.1 µF metallised polyester or ceramic (5mm lead pitch) Resistors (0 .25W, 5%) 1 10kQ 4 2.2kQ 1 1.8kQ 1 100Q Testing Once you've finished the board, you can install the fuse and power up the circuit. To do an initial test , use a LED and a lkQ resistor as the load for each transistor. If it is working cor- Miscellaneous Heavy duty cable, hookup wire, solder, etc rectly, each LED should come on in turn and the circuit should respond by either increasing or decreasing the chase rate as the 100kQ pot is rotated. If it doesn't work, check the board thoroughly for any solder splashes which may be causing shorts between the tracks. In particular, check between the IC pins. This done, check that all components have been installed correctly and that the correct value has been used at each location. Once the circuit is working with the initial LED load, you can then replace it with any load you choose up to 36W total for each transistor; ie, you could use 12 3W bulbs or six 6W bulbs, etc. SC Fig.3: here is the full size pattern for the PC board. Use it to check that your board has been correctly etched before mounting any of the parts. TABLE 1: RESISTOR COLOUR CODES 0 0 0 0 0 No. Value 4-Band Code (5%) 5-Band Code (1%) 1 4 1 1 10kQ 2.2kQ 1.8kQ 100Q brown black orange gold red red red gold brown grey red gold brown black brown gold brown black black red brown red red black brown brown brown grey black brown brown brown black black black brown APRIL 1991 55 A synthesised stereo AM tuner, Pt.3 This month, we complete the construction of the AM Stereo Tuner by giving stepby-step alignment details. This job is simplified by taking advantage of the microprocessor control. By JOHN CLARKE The AM Stereo Tuner can produce very good sound quality but to achieve this, the tuner must be aligned correctly. You do not need any special instruments or tools apart from a plastic alignment tool and a multimeter. Alignment involves measuring voltages and adjusting the various coils and trimmers using off air stations as the signal source. The alignment tool can be purchased from your local electronics supplier. Don't use a screwdriver to adjust the coils. Its metal blade will upset the adjustment and you run the risk of cracking the ferrite slugs. Powering up Before switching on, make a final 56 SILICON CHIP check on the wiring and check that the fuse has been installed. This done, set your multimeter to read voltages up to 12VDC, connect its negative lead to the ground pin next to TP2, and switch on the power. The display should light and show 522kHz. If not, switch off and correct the problem before applying power again. The problem could be lack of power to IC1, so use your multimeter to check for continuity between its supply pins and its relevant voltage regulators (ie, between pin 12 and the output of REG2, and between pins 5 & 17 and the cathode of Dl 4). Now re-apply power and measure the voltages at the output of the regulators. Check that REG1 has an out- put of 12V and that REG2 and REG4 are at 5V. REG3 should have about 5.6V at its output. You should also check that the supply rails to the ICs are correct. IC2 should have +5V at pins 6, 12 & 18; IC3 should have +12V on pin 4; IC4, +5V on pin 3; IC5, +5V on pin 14; IC6, +12V on pin 4; IC7, +12V on pin 8; IC8 has no supply rail; IC9, +5V on pin 1. If all the supply voltages are correct, the tuner can be left powered up unless a fault is detected during the following tests or during alignment. The next step is to check the operation of the front panel display and switches. First, press the UP tuning button and check that the frequency readout increases from 522kHz to 1629kHz in 9kHz steps. Each memory LED should light when its respective switch is pressed. Initially, all the memories will be set at 522kHz. To program each memory, select the required frequency using the TUNING buttons, then press the :ME switch and the required memory switch. The :ME LED should extinguish as soon as a memory switch is pressed PHONE LINE AND MAINS FILTER/SURGE PROTECTOR Protection for nswering machines ord/ess phones acsimlles or if the ME switch is pressed again. If neither switch is pressed, the ME LED should automatically extinguish after five seconds. The SEEK control should at this stage send the tuner scanning up the frequency band. However, because the tuner is not yet aligned, do not expect the tuner to lock onto a station. Press any button to stop the tuner from seeking. Check that the programmed memories remain intact when the tuner is switched off at the power switch. If not , check that REG3 is supplying a 5V standby voltage to pins 5 & 17 of IC1 when the tuner is switched off at the power switch but not at the mains supply. (Note: the memories should also remain intact for several hours if the mains supply is interrupted, as indicated in Pt.1). Alignment To align the tuner, we need to make a series of adjustments. These are to ensure that the local oscillator and ferrite rod antenna tuned circuits track each other, and that the range of the varicap tuning voltage is within certain limits. The IF tuned circuits also need to be peaked for best signal output and widest audio bandwidth. Once this is done, the 3.6MHz oscillator is set for stereo reception and the 9kHz twin-T filters adjusted. Some of the alignment process involves switching from a low-frequency station to a high-frequency station and then back again, with the process repeated several times to ensure accurate tracking. This can be done quickly, since the stations can be programmed into memory for quick access. Local oscillator range The first step is to adjust the local oscillator so that it covers the range from 972kHz to 2079kHz. The microprocessor (IC1) does all the frequency measurements for us and controls the local oscillator via a varicap tuning diode. This ensures that the local oscillator operates at 450kHz above the frequency indicated by the display. In practice, all we have to do is ensure that IC1 remains in lock. This lock requirement can be met by ensuring that the varicap tuning voltage at test point TP2 operates between defined limits. The procedure is as follows: • Connect your multimeter between GND and TP2, select 522kHz on the display and adjust 12 for a reading of 0.9V. • Press the Down TUNING button once so that the display jumps to 1629kHz. Adjust trimmer capacitor Cl for a voltage reading of 8V. • Return to 522kHz (press the Up button) and readjust 12 for 0.9V. This done, select 1629kHz and readjust Cl for 8V. Repeat this process until the two voltages are within 0.1 V of the required values. The local oscillator range has now been set. The next step is to adjust the ferrite rod tuned circuit so that the RF stage tracks with the local oscillator. RF tracking The RF section is aligned by measuring the AGC voltage at TP1. During ensures that lightning, power surges and spikes do not reach your ccstly communication equipment as it ccnstantly monitors the PHONE line and the MAINS power line. Simply ccnnect to any existing power point, plug in your fax, phone, video, Hi Fi or any other 240 VAC operated equipment and a series of indicators shows the status of the mains power point while several MOV's and gas arrestors prevents access to damaging energy sources. The CPE P- 1 is fully Telecom and Dept. of Minerals and Energy tested and approved. Imported and distributed by: .ARISTI\ ELECTRONICS Available through the following retailers: Telegrafax PIL. 305-307 Sailors Bay Road. Northbridge. 2063. NSW. (02) 9585137 Geoff Wood Elec. 229Burns Bay Road. Lane Cove. 2066. NSW. (02) 427 1676. ANTRIM TOROIDAL TRANSFORMERS * 15VA t.o 625VA from st.ock with single 240V primary and dual secondaries, 2 x 6V to 2 x 55V. Standard models comply with IEC65(BS415). * 15VA to 2KVA to order with dual 120V primaries and your choice of secondaries. Compliance with AS3108(IEC742). UL506 and other standards available. * High power audio toroids available to order for 100V lines. * Comprehensive data sheet available. * Competitive pricing available for OEM and resellers. HARBUCH ELECTRONICS P/L 90 GEORGE ST. HORNSBY, NSW PHONE (02) 476-5854 FAX (02) 476-3231 APRIL 1991 57 The ferrite rod assembly is adjusted by sliding coil L1 along the rod, as described in the RF tracking adjustment procedure. After the adjustments have been made, the coil can be held in place by melting wax over both ends. the ferrite rod slowly, noting the voltage reading for each movement. Take your hand away before making each reading and have the ferrite rod angled away from the tuner case by at least 15°. Adjust the coil for a minimum voltage reading. • Select memory 2 and adjust trimmer Cl for a minimum reading on your multimeter. • Select memory 1 again and re-adjust Ll for a minimum voltage reading. • Repeat the procedure for the memory 2 station, then check the memory 1 adjustment again. The two settings should now be correct. • Connect your multimeter between TP2 and GND and select the 20V range. Check that the varicap tuning voltage is at least 0.9V when the display is set to read 522kHz. If the voltage is below this, readjust the LZ slug for a reading of 0.9V. • Set the display to 1629kHz and check the voltage reading. If the voltage reading is above 8.5V, the local oscillator range will need to be reset as described previously. This also means that the RF tracking will have to be readjusted as described above. Fortunately, all these adjustments can be done quite quickly. IF alignment Heatshrink tubing should be shrunk over the ferrite rod assembly at the conclusion of the alignment procedure. This will provide a degree of protection against bumps & knocks & will further ensure that coil L1 is locked firmly in position. this process, you need to slide Ll along the ferrite rod to find the point of maximum signal pickup when tuned to a low-frequency off-air station. Cl is then adjusted for maximum signal pickup when tuned to a high-frequency off-air station. Using Cl to peak Ll means that the local oscillator varicap voltage range is altered again, and so this will require further readjustment. But that's 58 SILICON CHIP life. Here's the step-by-step procedure: • Select a local radio station which is near 603kHz and tune to this station. Now program it into memory 1. Select another local radio station around 1305kHz and program this into memory 2. • Connect your multimeter between TPl and GND and set it to the 2V range. • Select memory 1 and slide Ll along The mixer coil (L3) and the IF coil (L4) must now be adjusted so that the tuned circuits peak at 450kHz. When peaked, they will provide the best audio bandwidth for the tuner. • To align the IF stages, connect the multimeter between TPZ and GND and select the ZV range. Now select a radio station (memory 1 will do) and adjust the slugs in L3 and L4 for a minimum voltage reading. • Now go back and realign the RF section (ie, repeat the procedure set out under "RF tracking"). This is done because with the IF coils peaked, you will be able to more accurately peak the RF coil (Ll). After the RF stage has been realigned, the 450kHz IF coils (L3 & L4) should be readjusted. • When these adjustments have been completed, secure the antenna coil (Ll) by melting wax over both ends. This done, fit heatshrink tubing over the entire assembly (including the PC board), as shown in the photograph. Signal level display At this stage, you will be able to Be sure to use a plastic alignment tool when adjusting the various coils on the PC board, otherwise you could damage the ferrite slugs. Note that all the adjustments are repeated several times, as detailed in the text, to obtain the optimum result. check the signal level display for correct operation. Tune to various stations using the Up and Down TUNING switches and check that the signal level display operates correctly. On strong stations, all five LEDs should be lit. You can adjust the angle of the ferrite rod for best signal pickup. 3.6MHz oscillator The 3.6MHz oscillator coil (L5) must be adjusted so that this oscillator locks onto the 450kHz IF. Thi'.s will enable the tuner to provide a stereo signal. The procedure is as follows: • Connect your multimeter across the 2.2kQ resistor on pin 3 of IC2 and select the 5V range. Tune to a local station and adjust L5 until the voltage increases to about 2.5V. If the station is transmitting in stereo, the voltage should then suddenly increase to 4.5V and the stereo LED should light. • Rotate L5's slug slowly clockwise and note the position where the voltage drops to 0V from the locked 2.5V setting. This done, rotate the slug anticlockwise and again note the position where the voltage drops to 0V. Set the slug midway between these two positions. Seek control The seek control adjustment is made with trimmer capacitor C2. This sets the seek sensitivity so that it only locks onto stations with good signal strength. • Press the SEEK button and check whether the tuner stops at a station. If it doesn't, adjust C2 for greater capacitance (ie, plates further in mesh) and try again. Conversely, if the tuner stops at every 9kHz step, adjust C2 for lower capacitance. C2 is correctly set when the tuner only stops at stations with at least one LED lit on the signal strength meter. 9kHz filters The twin-T filters are designed to provide a notch at 9kHz in the audio path, to filter out adjacent channel interference. There are two adjustments to be made for both the left and right hand channels. This can be done using off-air stations at night when 9kHz whistles are prevalent. • Switch the power off and set your multimeter to the kilohm range. Connect the meter probes to the top of the 18kQ resistor (ie, the junction of the two 270pF capacitors) in the left channel and to pin 8 of IC3. Adjust VR3 for a reading of 32. 76kQ. • Similarly connect the meter probes to the top of the right channel 18kQ resistor and pin 14 of IC3 and adjust VRl for a reading of 32. 76kQ. • Rotate VR2 and VR4 fully cl ockwise. This should give a notch which is close to 9kHz. Note: if these trimpots are rotated fully anticlockwise, the twin-T filter will be disabled. • Connect the tuner to an amplifier and tune to a station at night which has a substantial whistle. Use the balance control of your amplifier to select the left channel only and adjust VR4 until the whistle is eliminated. Similarly, select the right channel only and adjust VR2 so that the whistle is minimised. Your new tuner is now ready for stereo hifi listening. In some cases, the ferrite rod may have to be adjusted to give the best reception although this will not be necessary on strong local stations. This simply involves angling the rod away from the rear of the case to increase signal pickup. SC APRIL 1991 59 HUGE STOCK CLEARANCE PRICES DRASTICALLY REDUCED ON MOST ITEMS See Altronlc's new 1991 catalogue for our full range. If you haven't received your copy yet, send $1 to cover postage and packing to: AL TRON ICS MAIL ORDER, PO BOX 8350 PERTH STIRLING ST, W.A. 6849. roduclng Altronic's New Sensational Labtech 20 MHz CRO Australla's Best Value In High Rellablllty, Top Performance Cathode Ray Oscllloscope. This model is a dual trac.e 20MHz Oscilloscope using a hi~h brightness CRT. The vertical amplifiers have high sensitivity of 5mV div and a frequency characteristic response with smooth roll off exceeding 20MHz. The TV sync. si~nal separator circuit is provided to ensure stable observation of video signals. Triggering is obtained by sampling . the AC power waveform, external waveform or internally generated trigger. Power consumption is only 19 watts and weig ht is only 7kgs. $ Full 12 Month• Warranty • Q 0156 FANTASTIC VALUE AT ONLY Probe Sets Q 0175 $49.95 each 699 Speclllc ■ Uon1 Position x 10 Bandwidth: DC to SOMHz Max Input Voltage: 600 Vo lts DC Position x 1 Bandwith: DC to 3MHz Max Input Voltage: 600 Vo lts DC Probe Length: Approximately 1.5 meters End Poly Emulsion Coated Cone Woofers at Direct Altronic Distributors announces the release of a new generation of high end woofers. The development of high grade driver components in Japan, such as Barium ferrite magnets and specially formulated paper cones impregnated with po ly emu lsion, have enabled us to offer our customers drivers of quite remarkable power handl ing, performance and extremely low distorition. We bel ieve the performance exceeds that obtainable from many European ··name" brands; and the direct import prices Cone Materials. This series of loudspeaker features a specially selected fibre impregnated paper cone which is coated with a layer of polypropy lene to c:dd the desired rigidity. An added benefit .of this coating is its resistance to water and moisture ingress. Voice Coil Construct1on. All voice coils are wound on aluminium. the magnet pole pieces are vented for heat dIssIpat1on. Bump back plates are employed to allow extra voice call excursion . · Rated Power .40W Max. Power ... 60W Impedance .... Sohm Freq. Rasp . ... F0-5kHz Res. Freq .... ... 70Hz (+/ -14Hz) Sensitivity ..... 96dB/ W(0.5m) Magnet .......... 567 gm/20oz C 3022 $49.95 ':CC' Woofer W MS 100W C 3024 $69 .00 21st Century entertainment fascinate your friends! Amazing! Pulsating high voltage plasma discharge continually changes shape and direction. Mode selectable to either fingertip control or sound activated . For example, from voice or sound system. Provides endless fascination as it sizzles and arcs. Supplied complete with AC mains adaptor. A 0120 Normally $199.oo SAVE $50.00 M ■x . Rated Power .60W Max. Power. .. 100W lmpedance .... Bohm Freq. Resp .... F0-4kHz Res. Freq ....... 60Hz (+/-12Hz) Sens itiv ity ..... 9BdB/W (0.5m) Magnet .......... B48gm/ 30oz 10" PECC Woofer 80 Walto RMS 130W Max . Rated Power .SOW Max. Power ... 130W Impedance .... Bohm Freq. Resp .. .. F0-4kHz Res. Freq ...... .2BHz (+/-SHz) Sensitivity ... .. 97dB/W(0.5m) Magnet .......... 1170gm/41oz 12" PECC Wooter 15" PECC Woofer 80 Walla RMS 160W Max . 100 Walla RMS 200W Max . Rated Power .BOW Max. Power ... 160W Impedance .... Bohm Freq. Resp .... F0-3kHz Res. Freq ....... 25Hz (+/ -SHz) Sensitivity ..... 98dB/W( 0.5m) Magnet .......... 1408gm/50oz Rated Power. 100W Max. Power ... 200W Impedance ....BOhm Freq. Resp .... F0-3kHz Res. Freq .... .. 25Hz (+/ -SHz) Sensitivity ..... 98dB/W(0.5m) Magnet ...... ....1835gm/65oz c 3026 $99.95 c 3030 $125.oo c 3032 $198.oo MICRON SOLDERING STATION Electronic Temperature Controlled-Temperature Selectable, Soldering Station . Now th is is really quality and versatility! Now supplied with long life ceramic cartridge heater. The MICRON T2440 T 2440 soldering station offers the ◄ CK. ultimate in controlled ~;,.95 temperature, hand soldering. Simply rotate detained rotary switch · freely to selectable fixed temperatures of: 320° C (608°F), 350°C (662°F), 380°C (716°F) 410°C (770° F), 440° C (824 ° F) without changing heater or tip. Packed with features: Temperature readout & control; Zero voltage switching; Grounded tip; Low voltage element; Chrome plated, iron clad tip. $ $139 BAG YOURSELF A KIT BARGAIN! FM Stereo Transmitter (See sc Oct e __, <at> K 1120 $~o $39.50 '88) Simply connect your CD player to the mini mitter which converts the CD signal to an FM signal. This FM signal then can be tuned In via your FM walkman or your shed radio. Great for listening to your favourite CD while washing the ca r, mowing the lawn or doing the vacuuming etc, without blasting the neighbours. AC/DC Millivolt Meter (See Ea Dec '87) Precision measure critical circuits. • AC/ DC range • 7M Ohm input impedance • 10mV to 30V ranges in 8 steps • Zero position • Battery Test position K FEATURES: ·- K 3210 $~00 $99 .oo 2670 $~0 $45 .00 Door Minder (See SC Feb '88) . This project will sense a door opening in a large or small room and will sound a two-ton e chime. It does not have to be anywhere near the doorway as it uses an ingenious sensor to detect the pressure change caused when the door opens. K 191 5 $Ji':f)o $34 .50 The Electronic Canary Get th at atmosphere of tra nqui lity that o nly birds can gi ve . The rea lism of t his proj ect is remarka bl e. Sou nds for all the world like two tr illi ng canaries. • Saves t he mess of birds • Battery powered • Easy to bui ld K 1130 ~ 5 $19.95 Automatic Charger for NiCads·csee EA July '89) 24V to 12V DC Converter (See SC Dec '87) This supply was designed to enable 12V appliances ~ like stereso , 2 Way Radios, .· CB 's etc. to ope rate from a (I, 24V battery supply as used in trucks , 4WD's and boats , · w ithout causing expensive damage to the vehicle . battery system . K 3255 $~ • Output variable between 3 and 30V • Short circuit protection • Full 1 amp output over entire voltage range • Load switching • Current limiting fully variabletwin selectable ranges-dual scale ' meter • Separate earth terminal provided • Housed in our Deluxe "ABS" in-,trument case. • · .· · • _......,_,..~..:..JU 0 $49.00 50MHz Digital Frequency Meter (See EA May '88) Easy to build & construct t his fantastic meter measures to well over 50MHz in 5 ranges. Features high input impedance, overflow LED indicator, KHz & MHz LED indicators. All componenets mount onto single PCB , even the selector switch. K 251 0 ~ o $89.oo K 1650 ~ o $29.95 Get 100's more recharge cycles from your nicads. Its now well kno wn that correctly charging nlcad cells greatly extends their service life. Here is a fully automatic NiCad battery ch arger that enables differing charge rates as appropriate for AAA , AA, C, D cells or cells in series up to 9V. On ce the battery is charged , the unit automatically switches to trickle charge until you switch it off. It is fully featured, yet surprisingly simple. ···· Telephone Off Hook Indicator Use where 2 or 3 phon es are connected on one line . If one extension is in use a LED wil l f lash in each of the other extensions . Req ui res no _external supply. K 1400 $9 .95 Speech Synthesizer Here is a self contained Speech Synthesizer that does not require a computer to control it. (ETI March '88) Low Cost Temperature Probe Here's an easy to build probe which adapts a . multimeter or electronic · voltmeter into a general purpose thermometer. Ifs Just the shot for measuring heatsink temperatures, how hot it gets inside your car, or where little Johnny has a fever! Measurer& accurately from 20 deg.C to =120 deg.C. K 2570 $21 .95 K 9500 $J).i':1)0 $ 89.oo K 9502 Pre-Programmed E rom for K 9500 $20.00 This small, simple circuit contains all th e necessary components to make your favourite possessions speak . It can be connected to almost any appliance, vehicle or home ~emote control system to let you know when the kettle has switched off , the doors are locked or the water in the radiator is boiling . The inputs are coded and priori ty message reading means warnings are heard instead of greetings etc if two messages are sent at the same time. Blank Eprom included to allow you to program the messages you want. Terrific 18 Range Digital Multimeter • 3.5 Digital LCD • Compact Design 128x75x24mm • DC Voltage 5 Ranges: 100uV to 1000V • Input Impedance: 1M Ohm • DC Current 6 Ranges: 0.1uA to 10A • Overload Protection • Resistance Measurement 5 Ranges: 0.1 Ohm to 2000k Ohm Now Available Nine Great New Model• with Raw Aluminium, Natural or Black Anodl1lng Each finish is available in 44mm, 88mm or 132mm high models. Mounting hole centres conform exactly to International Racking Specifications both vertically and horizontally. FANTASTIC NEW MODEL DESIGNED BY ALTRONICS Feature, • Raw aluminium, black or crafter natural anodised finish. • These beautifully crafter rack cabinet boxes will give your equipment a really 1st class appearanpe. • Aluminium construction with removable top and bottom steel cover panels. • All dimensions conforms to the International Standard. • Ventilated lid. • Delu xe finish front panel. • Individually cartoned . • Supplied in Flat Pack Form - Easily assemble in minutes. a 1054 $~5 $32.95 a 1057 Carry Case $12.50 Two Brilliant I Multitesters From Altronics at Low Direct Import Prices Multimeter with Temperature Meter, Capacitance, Diode and Transistor Tester - A Logic Tester, Frequency Counter, Capacitance and Transistor Tester a 1010 $.1,.89':'oo $159.oo Side Elevation: D = 254mm C = Internal Chassis Height B = Mounting Bolt Centres Cat No. H 5011 H 5012 H 5013 H 5021 H 5022 H 5023 H 5031 .... a 1067 Temp. Probe $29.95 · H 5032 H5033 ,--l 1U 2U 3U 1U 2U 3U 1U 2U 3U A 44 88 132, 44 88 132 ' 44 88 132 · B C 32 76 54 · 32 76 54 32 76 54 38 79 122 38 79 122 38 79 122 Flnllh Ea. Raw Alum. Raw Alum. Raw Alum. Nat Anod. Nat Anod. Nat Anod. Blk Anod. Blk Anod. Blk Anod . 59.95 78.95 82.95 65.95 82.95 89.95 65.95 82.95 89.95 !7~~ 76.95 80.95 63.95 80.95 . 87.95 63.95 80.95 87.95 Blank Rack Panels 0°F to 1400° F Logic Teat (Q 1070 only) Logic 1 2.4V +/- 0.2V, Logic 0: 07V +/ - 0.2v Frequency Range: 2kHz. 20kHz, cat No. H 5111 H 5112 Accuracy:+ / - (3° + 1 dgt) up to 150° C +/- 3% rdg over 150° C +/ (15° + 2 dgts) up to 225°F 200khZ, 2MHz, 20MHz Input Sensitivity: 20MHz range 1V" rms. Other ranges 35mV rms. H 5121 Temperature Range: -20° C to 750° C Unit Height • • Revolutionary new extruded design eliminates the need for visible boltheads through the front panel DC Voltage Range: 200mV, 2V, 20V, 200V, 1000V Accuracy: All ranges+/- 0.5% rdg + 1dgt Input Impedance: 10M Ohm AC Voltage Range: 200mV, 2V, 20V, 200V, 750V Input Impedance: 1OM Ohm DC Current Range: 200uA, 2mA, 20mA. 200mA , 10A AC Current Range: 200uA, 2mA. 200mA, 10A ReIlItance Range: 200Ohm. 2k Ohm. 20k Ohm. 200k Ohm, 2M Ohm. 20M H 8113 H 5122 H 5123 H 5131 H 5132 H 5133 Unit Height Flnllh 1U 2U 3U 1U 2U 3U 1U 2U 3U Raw Alum. Raw Alum. Raw Alum. Nat Anod. Nat Anod. Nat Anod. Blk Anod. Blk Anod. Blk Anod. Ea. 9.95 17.95 25.95 12.95 20.95 27.95 13.95 22.95 29.95 59~~ 16.95 24.95 11.95 19.95 26.95 12.95 21.95 28.95 Super Large Instrument Case Ohm, 2000M Ohm Capacitance Range: 2000pF, 20nF, 200nF, 2uF, 20uF TranIlItor hFE Baae DC Current: 10uA, VCE: 2.8 +/- 0.4V General: Dlapl ■y: 3 1/2 digit liquid crystal with maximum reading of 1999 Overrange Indication: Highest digit of (1) or (-1 _) is displayed BATTERY OPERATED PORTABLE P.I.R. INTRUSION ALARM Ward off thieves and Intruders at home and when travelling . This super handy, go anywhere P.I.R. alarm system Is great for shop, office, caravan, boat, garage and whenever you are travelling. Hobbyists and manufactuers alike will find our new desk mounting case really fantastic for the larger projects. The case has 11enerous ventilation slots on both the top and bottom panels, a myriad of mounting posts are provided for PCB's and "extra tough" mounting posts are included for securing transformers. Additional ventilation has also been provided for the mains transformers and power supply locality. • Designed to house amplifiers, inverters, power supplies, microprocessor equipment, etc. • Mounting posts provided for PCB's, transformers. • Vented for efficient air-flow cooling.• Extra tough, super finish front and rear panels. • Dimensions: 355 x 250 x 122. FEATURES: • Exit delay • Entry delay • Large coverage - up to 100 square metres • Low battery LED Indicator • 9V Alkaline battery (not supplied) lasts many months. s 5305 $~0 $49.oo SUPER GUARD HOUSEHOLD ALA'IM SYSTEM • Easy to operate Simplicity itself - just select the switch to Home, Off or Away as desired . A 45 second exiVentry delay allows you to vacate and/or re-renter your premises and disarm the system. • No key switches or code buttons to - - Extremely eaey to /natal/, H 0491 Black Case or H 0492 Blue Case $39.95 Die Cast Boxes When you need a box that's rugged, robust and virtually indestructable then these have to be the answer. Apart from the sturdiness they also offer a high degree of 1 ~~~~~~nJlave inbuilt slots for accepting P.C.B.'s. ·· Three sizes to choose from: · ~Fi ~~~~- the system is ideal for families even the kids can operate this system. • Facility for external siren.• Battery backup (battery 8 'C' cells not included) H 0451 $7.95 10 Up $7.50 (98 x 50 x 25mm) l,atem Contente: • Master Control unit • Front Door Bell Switch • Panic/Emergency Switch • Three Window/Door Reed Switches • Mounting Hardware • 20 Metres Wire . • Instruction Manual. $ H 0490 Grey Case ' H 0453 $9.95 10 Up $9.20 - ---~-·--5465 $~O nOW (118 x 60 x 40mm) $85.oo H 0455 $24.50 10 Up $23.10 (188 x 108 x 60mm) Why Pay A Commercial Security Firm A Fortune To Wire Your House Or Office. This Fantastic System Installs In An Hour Or Two And Uses No Wires Hurry-Stocks Limited At This Price/ Specials This Month Only Features: • Wireless reception of external or internal sensors or detectors . • Selectable home or away modes for selecting internal and external arming or just external to allow movement inside the building. • Built in Piezo electric si ren gives different signals to indicate different functions. • Sends signal down power line to activate one or more remote sirens. • Programmable arm/disarm switch buttons. The main control receiver runs on 240V AC with a 12V 1.2AH battery for emergency backup. All other units with the excepion of the line carrier, run on a 9V battery each. The average life expectancy is approximately one year. System works around 305MHz frequency where there is less chance of false alarm. The range of the unit is normally 80 metres in open space. Main Control Receiver Passive Infra Red Movement Detector Ideal fo r t he loungeroom, family room or hall ways. Moun ts up on the wal l or on top of bookshelves etc. Detects movement wit hin area of 9M by 9M. 5280 $Jw.6"o $89.oo Hand Held Control Transmitter Unit Keep it at t he bedside table - al lows you to arm th e house perimeters whe n you reti re or yo u can take it with you when you go out, arming yo ur syste m after you lock the door. Take It With You If You Move s 5275 UEr.fio $45.oo Remote Plezo Alarm This unit is an optional li ne carrier receive r. Receives signal th rough 'AC' line i.e. it would ideal ly be located in, say, the roof space and plugged into mains power. s 5290 $j.25':'oo $89.oo s 5265 $ ~ $289.oo Complete System Special Package Price One One One One S 5265 Main Controller •cl'M't": S 5270 Reed Switch S 5260 $~~.00 S 5280 Passive 1/R Detector S 5285 Wall Control Unit .00 Accessories $489 Detector/ Transmitter Unit (Reed Switch) Suitable for Windows and Doors Th is con sists of an enclosed reed switch and compact UH F transmitter and a removable enclosed magnet is mounted on the door or window frame with the magnet on the moving door or w indo w. S 5270 45.oo MORE AL TRONICS DEALERS WANTED If you have a Retail Shop, you could Increase your Income algnlflcantly by becoming an Altronlca Dealer. Phone Brian Sorensen (09) 328 2199 for Delalla. Altronlca Resellers Altronlc1 Malt Order P.O. Box 8350 Perth Stirling Street W.A . 6849 STAN DARD DELIVERY & PACKING CHARGE $5.50 to 1Kg, $8 1Kg-5Kg AUSTRALIA WIDE - We proce ss your order th e day received and despatch via Austra lia Post. Allow appro x 9 days from day y ou post o rd er to when yo u recei ve goods. OVERNIGHT JETSER VICE Up to 3Kg is $10.00, 3Kg to 5Kg is $28 .00 - We process your order the day recei ved and despatch via . Overnight Jetservlce Courier for de livery ne xt day Count ry area s please allow additional 24-48 nours. HEAVY HEAVY SERVICE - All orders of 10Kgs or more must travel Express Road - Please allow 7 days fo r de li very. $1 2.00 to 10Kgs. $15.00 over 10Kgs. INSURANCE - As with virt ually every other Austral ian supplier. we send goods at consignees risk . Should you requi re comp rehensive insurance cover against loss or damage please add $1.00 per $100 of order value (min imum charge $1 ). When phone ordering please req uest " Insurance". TOLL FREE PHONE ORDER - Ban kc ard. Visa. Mastercard Holders can phone order toll free up to 6pm Eastern Standard Time. Remember with our Overnight Jetaervlce we deliver next day. Chances are there is an Al troni c Resel ler right near yo u - c hec k this list o r phone us fo r details of the nearest dealer. Blue Ribbon Dealera are highli9hted with a ■ Th ese dealers generally carry a com prehensive range of Altronic produ cts and kit s or w ill order any required ite m fo r yo u. Don 't forget our ExpreH Mall and Phone Order Service - tor the coot of a local call, Bankcard, Visa or Mastercard holders can Phone Order for same day deopatch . Please Note: Resel lers have to pa y the cost of'freight and insu rance and therefore the prices charged by individual dea lers may vary slight ly from thi s Catalogue - in many cases, however , Dealer prices w ill still represent a significant cost saving from pri ces cha rged by Alt ron ics Co mpeti tors. Blue Ribbon Dealer1 are highl ighted with a ■ These Dea lers generally carry a comp rehensive range of Alt ro nic products and kits or will orde r any required item for you. WA COUNTRY ALBANY BP Electronics ■ (098) 412681 Micro Electronics (098) 412077 BUNBURY Micro Electronics (097) 216222 ESPERANCE Esperance Communications (090) 713344 GERALDTON Batavia Lighting & Electron ics (099) 211 278 KALGOORLIE Todays El e c t ronic s ■ (090) 215212 MANDURAH Micro Electronics (09) 5812206 PORT HEDLAND Ivan Tom ek Electronics (091 ) 732531 ROCKINGHAM TV Joe's (09) 5271 806 NT ALICE SPRINGS Farmer Electronics (089) 522388 DARWIN Ventronics (089) 853 622 ACT CITY CANBERRA Bennett Comm . Electronics (062) 805359 VICTORIA CITY All Electronic Components (03) 6623506 The Electronic Component Shop ■ (03) 6706474 SUBURBAN BORONIA,Ray Cross E lect roni cs ■ (03) 7622422 CHELTENHAM Talking Electronics (03) 5842386 CROYDON Truscott Electronics ■ (03) 7233860 PRESTON Preston El ectronics ■ (03) 4840191 COUNTRY BAIRNSDALE LH & LM Cra wford (051) 525677 BALLARAT Ballarat Electronics (05fil 311947 BENDIGO KC John son ■ (_0541 411411 MILDURA Mcwilliam Electronics (050) 236410 WARRNAMBOOL Koroit Electronics (055) 627417 QUEENSLAND CITY Delsound PL ■ (07) 8396155 SUBURBAN CAPALABA Kingsway Electronics (07) 3902399 NEWSTEAD EGO Electronics (07) 25411 53 WEST END B.A.S. Audiotronics (07) 8447566 WOODRIDGE David Hall Electronics ■ (07) 8082777 COUNTRY BUNDABERG Bob El kins Elec tronics (071) 721785 GLADSTONE Gladstone Electronic Services (079) 724459 MACKAY Philtronics (079) 578855 MAROOCHYDORE MALS E lect ron ics ■ (074) 43611 9 MARY BOROUGH Keller Electronics1071} 21 4559 PIALBA Kel ier Electron ics (071) 283749 ROCKHAMPTON Access Electronics (East St.) (079) 221058 TOWNSVILLE Super Solex ■ (077) 724466 SA CITY Force Electronics ■ (08) 2125505 SUBURBAN BRIGHTON Force Electronics ■ (08) 3770512 CHRISTIE& BEACH Force El ectroni cs ■ (08) 3823366 ENFIELD Force Electronics ■ (08) 3496340 FINDON Force Electronics ■ (08) 3471188 LONSDALE Force Electronics ■ (08) 3260901 COUNTRY MT,GAMBIER South East Electronics J087) 250034 WHY ALLA Eyre Electronics (Otlfil 454764 TASMANIA HOBART George Harvey ■ (002) 342233 LAUNCESTON Geo rge Harvey ■ (003) 316533 NSW CITY David Reid Electronics ■ (02) 2671385 SUBURBAN CABRAMATTA M & L Electronics (02) 7274431 CITY SOUTH Sheridan Electronics (02) 2817727 SMITHFIELD Chantronics (02) 6097218 REVESBY Electronics (02) 792 2295 COUNTRY COFFS HARBOUR Coifs Habou r Electronics (066) 525684 GRAFTON East Coast Electronics (066) 431250 NEWCASTLE Novocastrian Elect.Supplies (04g) 62 1358 RAYMOND TERRACE Alback Electronics (049) 873419 WAGGA WAGGA PHILLI PS Electronics (069) 21 6558 WARNER& BAY Vilec Distri butors (049) 489405 WINDSOR M & E Elect. and Communications (045) 775935 WOLLONGONG Newtek E lectronics ■ (042) 271620 Vimcom Electronics (042) 284400. A practical approach to amplifier output stage design - Pt.2 Last month we introduced the topic of amplifier output stage design and looked closely at the selection of output transistors. In this article, we look at driver transistor selection and then calculate the heatsink requirements. By DAVID EATHER Last month, we concluded with Tables 3 and 4 which were the load line calculations for the driver transistors in the circuit of Fig.1, a straightforward 25 watt amplifier. The next step is to go to your data book and draw the SOAR curves for the BD139/140 transistors. Having done that, plot the load lines from Tables 3 and 4 on to the same graphs. When you have finished, you should find that the curved load lines are fully enclosed by the straight line SOAR graphs. The complete plot was shown in Fig.3 and shows that BD139/140 driver transistors are indeed quite suitable for this application. For convenience, we reproduce Fig.3 in this article. With this done, you have finished selecting the output and driver transistors. Now we will move onto calculating the heatsink requirements of the amplifier. This is where, if you made 64 SILICON CHIP the right choices for transistors, it all comes together. Selecting the heatsink The object of selecting a heatsink is to keep the transistor junction temperature below the maximum permissible while still allowing it to dissipate the required power. If the junction temperature rises above the specified maximum, the transistor will probably fail. In any case, it makes good sense to keep the transistor junction as cool as possible. Every 10°C lower approximately doubles the transistor's life. When considering how a transistor dissipates heat, it is useful to think of Ohm's Law. The heat produced by the transistor chip is analogous ,to current. The actual temperature at any point is similar to voltage and thermal resistance is like electrical resistance. Fig.4 is a simplified thermal model of a single transistor mounted on a heatsink. Notice that there is a resistance between the transistor junction and the transistor case (Rth j-c). This is one resistance you can do nothing about. The method of manufacture and the type of transistor case determine Rth j-c. The other thermal resistances you do have some control over. These include the case to heatsink (Rth c-h) and heatsink to ambient (Rth h -a) resistances. All the components also possess some thermal capacitance. When heat is produced at the transistor junction, the temperature does not rise immediately but climbs more slowly to the peak value. The values of thermal capacitance for the transistor chip, case and washers are small when compared to even a modest heatsink. So for this reason, it is possible to ignore them without significantly affecting the results, in most cases. There is another thermal path that you should be aware of, even though I won't use it here. It is the heat flow from the case to the surrounding air. The specification is given as either case to ambient (Rth c-a) or junction to ambient (Rth j-a). Either way, it acts as a parallel resistance from the specified point (junction or case). The net effect is to lower the total thermal resistance to ambient. Sometimes there is no value specified or the value is so large that it makes little diffe~ence to the final r~sults. Calculating how to keep the transistor junction at a safe temperature is easiest by using the SOAR curves/load lines you have already plotted. You also need to use the temperature derating curves on the data sheets or the formula given later. At this point, there is no longer any advantage in considering the output 10 .... "\ \ \ __ill ,__Jill 0.1 I\ I\ I'\ I\ I I I \ .01 \\ 1 10 100 Vee (V) Fig.3: repeated from last month, these curves show the load lines for the driver transistors (plotted using the data shown in Tables 3 & 4). As with the output devices, the load lines must be fully enclosed by the DC SOAR curve of the transistor. at the same voltage while the current changes. Make sure that part of the SOAR curve just touches the outside of the transistor load lines. Check that the load lines are still fully enclosed by the new SOAR curves. My new graphs are Fig.5 and Fig.6. Power dissipation is the limiting factor for Fig.5 because the curved load line touches the upper set of sloped lines (which represent the power dissipation limit). In Fig.6, secondary breakdown is the limit because the curved load line touches the lower set of sloped straight lines (which represent the SOAR-limited power dissipation). Look at the power limited section of the new SOAR curves. At a convenient point on the curves, calculate the maximum derated power dissipation. Do this calculation even if secondary breakdown was the limiting factor with your transistor. Note the figures down. Mine are 84 watts for the output transistors (Fig.5) and 5.5 watts for the drivers (Fig.6). 0 I'\ 10 )\~ I'\ I'- .... .... I, 1'. ' ' 1'. .... - --~1' .... I°' I'-... \ [/ I -....."- \ \ "" l\ \ \ 'I 'l 0.5 I I \ \ 0.3 \ \ ' 20 10 30 60 Vee(V) Fig.5: graph showing the derated SOAR curve for the output transistors. This curve is derived by constructing new power limited & secondary breakdown lines parallel to the original lines, so that they just touch the transistor load line. Maximum case temperature ....., ,-JUNCTION TEMPERATURE RTH(j·e) , CASETEMPEAATUAE RTH(e-h) • HEATSINK TEMPERATURE RTH(h•a) •-:-• AMBIENT TEMPERATURE Fig.4: simplified thermal model for a single transistor mounted on a heatsink. If available, use the temperature derating curve on the data sheet to find the maximum permissible case.• temperature. Some data sheets have the graph scaled directly in watts while others may use a percentage of the maximum power. The data sheet for the.BD139 comes with a temperature derating graph. This graph gives a maximum case temperature of95°C. Those data sheets without temperature derating curves can use the following formula to calculate the maximum case temperature: 10 .... "\ ,_ Derated SOAR curves On the load line graphs you have to find how far the transistor SOAR curves can be derated while fully enclosing the load line. Draw derated SOAR curves by constructing new power limited and secondary breakdown limited lines parallel to the original lines. The point where the "power limited" line becomes secondary breakdown remains Tj max is the maximum temperature of the transistor junction. At Tj max, the transistor's power handling drops to zero. 200°C is the most common value for hermetically sealed transistors (metal case) and 150°C for most non-hermetic (plastic) types. P is the derated power of the transistor from above. Pmax is the maximum power the transistor can dissipate. Tj min is the highest junction temperature at which the transistor can dissipate Pmax. It is usually, but not always, 25°C and is next to Pmax on \\ '\l\ 0.1 ' I Tease max = Tj max - P/Pmax x (Tj max -Tj min) stage and driver stage separately. Apply the following steps to both stages. ' ""\ I I' I ~ .01 1 '\ \\ 10 100 Vee (V) Fig.6: graph showing the derated SOAR curve for the driver transistors. Note that· secondary breakdown is the limiting factor here, while power dissipation is the limiting factor for Fig.5. the data sheet. For example, Tj min for the 2N3055 is 25°C and for the BD139, 70°C. For the example of the output stage APRIL 1991 65 Amplifier output stage design ... in my design, the following values are derived from the data sheet: Pmax equals 115 watts; Tj maxis 200°C; and Tj minis 25°C. p· comes from the derated SOAR curve above and in this example is 84 watts. Poking all the numbers into the formula gives: Tease max = 200 - 84/115 x (200 - 25) = 200 - 0.73 X 175 = 72°C. Now is as good a time as any to decide what heatsinking configuration to use. Mathematically, the simplest approach is to mount each transistor on its own heatsink. This has some practical advantages too. With the heatsinks electrically isolated, the insulating washers are superfluous. The lower thermal resistance (Rth c-h) can result in smaller heatsinks or greater reliability. One problem (beside cost) is the greater difficulty in providing the bias current with thermal stabilisation. A common heatsink The most common approach is to mount all the transistors with insulating washers on a common heatsink. Check carefully to see if there are any other possibilities that could result in significant benefits. One example would be if you designed an amplifier with only the output transistors connected in common collector mode. Mounting these transistors without insulating washers is possible with an electrically isolated heatsink. This could lead to some savings with either the type of transistor used or size of heats ink. Fig. 7 is a simplified diagram of the thermal paths for my amplifier. I've used the commonest approach and mounted everything on the one heatsink and used insulating washers on all the transistors. The values used for Rth c-h are from Table 5 which is collated from a variety of sources. If you are using a transistor package 66 SILICON CHIP not listed in Table 5, make an ap proximation based on the mounting area of one of the listed packages. Heatsink compound Notice that the use of heatsink compound reduces the thermal resistance to one fifth, making it well worth using. There is one last formula to use before the completing the amplifier design. Truthfully, there is a little more than one but the rest are trivial. You have to calculate the average power dissipated in the transistors while driving the load. The formula is: Pave diss = [(Vee - Vripple/2) x Imax]ht - [Vmax load x Imax load x cos0]/4 Subtracting half the ripple voltage from Vee gives a simple approximation for the average voltage supplied to the transistors. Use the values associated with the nominal load impedance for your amplifier. The calculations for my output stage are: Pave diss = [(27 - 3/2) x 2.5]ht - (20 x 2.5 x cos45°]/4 = 11.41 watts. And for the driver transistors: Pave diss = ((27 - 3/2) x 0.125]/n - [20 x 0.125 x cos45°]/4 = 0.573 watts. Thif' is the average power dissipated Ti,01 Tj, 02 Tj, 03 2oo·c MAX 01 RTH(j-c) 01 RTH(c-h) Ti, 04 15o•c MAX 04 RTH(j-c) 02 RTH(c-h) o.JJ·ctw 03 RTH(c-h) 04 RTH(c-h) 3•ctw HEATSINK TEMPERATURE (MAX 68.23°C) RTH(h-a)? AMBIENT 4o•c .,. Fig. 7: simplified diagram showing all the thermal paths for the amplifier (note: driver & output transistors all mounted on the same heatsink). by the transistor when producing a continuous full power sinewave into the nominal load. As you would expect, these values are quite a bit lower than the peak values calculated earlier. This is not the worst case figure which is obtained when the output is shorted. Driving the amplifier into clipping also produces higher power dissipation. Both of these conditions are abnormal and can be protected against by the careful selection of fuses or electronic limiting. Now comes the part that is a little hit and miss, like fitting in the last parts of a puzzle. Exactly how you proceed depends on what you have to fit into place. The object is to find the heatsink size that allows the transistor cases to stay below the maximum temperatures calculated before. For my example, I have all the transistors on one heatsink and I'll proceed as follows. Heatsink size First, find the maximum permissible heatsink temperature for both transistor stages. This is simply the maximum transistor case temperature minus the thermal resistance to the heatsink times average power dissipation of the transistor. Tmax heatsink = Tease max - Rth c-h x Pave diss Remember that Pave diss is like current in Ohm's Law. The heat dissipated flows through a thermal resistance and produces a temperature gradient across it. Rth c-h comes from Table 5. For the output stage of my amplifier, the formula becomes: Tmax heatsink = Tease max - Rth c-h x Pave diss = 72 - 0.33 x 11.41 = 68.23°C. Similarly, for the driver stage, the maximum heatsink temperature would be 93.28°C. Because in this case all the transistors are mounted on the one heatsink, 68.23°C has to be the maximum allowable temperature. The next step is to find the total heat flow into the heatsink. This is a simple addition of the power dissipation of all the transistors. For my example, there is the power dissipated by the two driver transistors plus the power dissipation of the two output transistors. Table 5: Thermal Resistance (c-h) For Common Packages T0-3 T0-66/SOT-93 T0-220 T0-126 Insulating washer No heatsink compound 1.50 4.55 5.68 13.64 Insulating washer Heatsink compound 0.33 1.00 1.25 3.00 No insulating washer No heatsink compound 0.50 1.20 1.50 3.60 No insulating washer Heatsink compound 0.10 0.24 0.30 0.72 gives a compact design that will fit inside a "one unit high" rack mounting box. The larger heatsink also means that the amplifier will safely handle quite a bit of sustained thrashing. You beauty! Fuse selection This gives a total of 23.97 watts dissipation. Now make an approximation of the maximum ambient temperature inside the amplifier enclosure. 40°C is a commonly used figure. Another item to consider is the use of a mounting bracket for the transistors. The mounting bracket adds further thermal resistance between the transistor and the ambient temperature. In many cases, simply adding 5100C to the ambient temperature deals with the problem. But it is better to use the thermal resistance, if you know it. The final value ofheatsink thermal resistance is another simple application of Ohm's Law. You know the heat flowing in, the temperature gradient (maximum heatsink temperature ambient) and you need to find the thermal resistance. Rth h-a = (Tmax heatsink T ambient)/Ptotal dissipation= (68.23 - 40)/23.97 = 1.18°C per watt That's equivalent to just over 150mm of common fan type heatsink. Unless you need a very sturdy amplifier, such a large heatsink will almost certainly make this design uneconomical. Smaller heatsinks Fortunately, the situation of an amplifier delivering its full power on sinewaves for more than a minute is not common. Even the most determined organist is unable to remove every rest from a tune. Music and PA amplifiers produce peak power for only a small percentage of the time. This means you can use a smaller heatsink than shown above because the average power dissipation of the amplifier is much less. The large thermal capacitance of the heatsink will smooth out any high peaks in temperature. How much smaller can you make the heatsinks? There a two widely used rules of thumb that can help to guide you. The first rule of thumb says that with the worst case signal (rock music from an FM station), the average power dissipation equals 15% of the peak output. For my amplifier above , this would mean the heatsink needs to cope with an average dissipation of 3.6 watts. That works out to a thermal resistance of 7.8°C per watt: A piece of aluminium a bit bigger than normally used as a heatsink mounting bracket will suffice . The amplifier case would also be suitable. This size of heatsink makes the amplifier suitable for home use or anywhere it will be treated with some respect. The other rule of thumb is the peak music power figure which says the average power equals the peak power divided by 2¼. This usage has nothing to do with the shameless way some manufacturers use peak music power figures to boost sales. This calculates to an average dissipation of 10.6 watts, requiring a heatsink with a thermal resistance of 2.7°C per watt. Any of the multipurpose 75mm-long heatsinks will work. This amount of heatsinking gives an amplifier suitable for most professional and semi-professional applications. The choice of a 75mm-long fan type heatsink provides an interesting design. Mounting the transistors through the heatsink directly onto the PC board One furth er step is the selection of fuse protection. Fuses are not optional. It is true that the output transistors often blow before the fuse. Don't make the mistake of saying "the transistors often protect the fuse by blowing first". Fuses go open circuit, transistors normally go short circuit. If an output transistor goes short, the speakers are connected directly to your power supply. Without a 50-cent fuse , your expensive speakers can burn out. Should a fire result, you could find yourself being held liable for damages. Use a normal fast fuse between each supply rail and the output and driver transistors. This placement is preferable to using one fuse in-line with the speakers. If you are using a polyswitch or MOSFETs in the output, you may decide that it's OK to delete these fuses but you will still need the fuse in line with the mains as described later. For the output transistors, the fuse value is selected empirically. A good starting point is to make the fuse equal to Imax load divided by 3.18. This size fuse should allow the amplifier to produce a continuous sinewave output and allows a bit of clipping during music. Gross levels of clipping should blow the fuse. Use a slow blow fuse in line with the mains supply. This provides protection if the power transformer, bridge rectifier or a filter capacitor goes short. Its value should be: Fuse (slow blow)= Vee x (Imax load) X 0.71/240 For my amplifier, that comes out to about 200mA. Remember to make allowance for power drawn by other parts of the circuit. For low power amplifiers, it will be difficult to find a slow blow fuse near the value you need. The smallest value you can find will be OK. In any event, the slow blow fuse should only operate in response to catastrophic failures. That's it, finished. You should now be able to design reliable output stages for your amplifiers. So go to it. SC APRIL 1991 67 ,_, I , ~.,/i:.,~ 7,11, ' \ b1,I~.s-l.,~) ,;: _,~I 21 MEG HARD DISK WITHOUT C_ONTROLLER 42 MEG HARD DISK FOR XT 28 ms ACCES~ WITH IDE/FDD ., )~, CONTROLLER .............................$549 42 MEG HARD DISK FOR AT 28 ms ACCESS WITH IDE/FDD QUALITY CONTROLLER .............................$449 JAPANESE DRIVES!! 85 MEG HARD DISK FOR AT 5¼" 360K DRIVE • 500K unformatted, 28ms ACCESS WITH IDE/FDD • IBM · xr compatible Cat.C11901 ...... _ $175 CONTROLLER ........................... ,$795 51 /4' 1.2 M/BYTE 126 MEG HARD DISK FOR AT COPAL DRIVE •1.6M/Byteunformatted 16 ms ACCESS WITH IDE/FDD • IBM• AT• CO"llatible c119o6 ................ $150'. CONTROLLER .........................$1 ,295 , ._ ~ All Hard Disk capacities are formatted. IDE/FDD drives are already low level formatted so you only have to "F DISK" to high level format them. 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IBM' COMPATIBLE SPREADSHEET, WORDPROCESSOR & DATABASE SOFlWAREINCLUDED. $ , ________________ _________________ ·'"'""""' .------------------. ,-------------------,=--, RITRON [!IP':..._ ~ ~ RITRON [_i i EXECUTIVE EXECUTIVE ~; i1·) 1;., ( 386-56 ) ~~ ( 486-115 ~ ,i:,i ~ ~ ~~ J ~/ 16Mhz LANDMARK SPEED TEST 1.2M JAPANESE BRAND F.D.D 42M HARD DISK DRIVE 28ms ACCESS 101 EXTENDED :'CLICK" KEYBOARD JAPANESE KEYBOARD SWITCHES I\INI CASE & 200W POWER SUPPLY 256K VGA CARD SUPA VGA COLOUR MONITOR (1024 x 768 r<s) SERIAL, PARALLEL, GAME PORT 2 YEAR "AUSTRALIAN" PARTS & LABOUR WARRANTY DOS 4.01. IBM' COMPATIBLE SPREADSHEET, WORDPROCESSOR & DATABASE SOFlWAREINCLUDED. ASSEMBLED& TESTED ·. .__ IN AUSTRALIA. El ~- ~/ ill ~ 80286-16CPU 1 MEG RAM EXPANDABLE TO 4 MEG ( 386SX-27) ~ ) RITRON 80286-12CPU 1 MEG RAM EXPANDABLE TO 4 MEG RITRON --------. 286-20 ( ·1__11- __,~1/~~; :i~~ ~~ .. ~l~iii,/o \\\ ~ ~ 1 ) of ~ - -. /" /-- ~ J -_ ·_·~~ ~I:~r~,,,-~:· !: Yh;~ ·~~~ r ~~. 1 CIRCUIT NOTEBOOK Interesting circuit ideas which we have checked but not built and tested. Contributions from readers are welcome and will be paid for at standard rates. +12V INPUT 01 470k 01 T 100k .0 .,. k 3kHz LP BUTTERWORTH BUFFER 14 OUTPUT 300Hz HP BUTTERWORTH BUFFER 300Hz-3kHz audio filter A speech filter is often used to cut the bandwidth in transceivers in order to achieve maximum readability, or even to do tests on transmitting equipment. This circuit is a simple one-IC project and works in the following manner: Simple IR detector checks remote controls This simple tester can be built in a few minutes and can be used to check out some remote control transmitters, as used for TV sets, VCRs and hifi systems. The circuit is based on the GP1U52X Infrared Receiver/Demodulator (IC1) which is available from Tandy Electronics (Cat. 2 76-13 7) for about $7.00. It is supplied with a data IC1a is connected as a unity gain buffer stage. Its output is passed to a 3kHz low-pass Butterworth filter based on IC1b, which cuts frequencies above 3kHz at the rate of 12dB/ octave. The signal from pin 7 is then fed to a 300Hz high-pass Butterworth filter based on IC1c, which cuts frequencies below 300Hz at the rate of 12dB/octave. '1 ,. 9V : ...L.. i 2 R1 220!2 LED1 vcc I GP1 5~2X O/P 1 GND 3 .,. sheet detailing its features. When no infrared energy is present, the output of IC1 (pin 1) remains Another test for IR remote controls Here's a useful tip for checking baulky IR remote controls. If a control function is not working, the first step in troubleshooting is to determine whether the problem lies in the transmitter itself or in the receiver circuit. To test the transmitter, turn on your AM radio, tune it to a blank spot on the dial and hold the transmitter next to the ferrite rod antenna. Now press each control button in turn. In each case, you should hear a heavily modulated hum or whisle from the radio and the sounds should all be similar. If the sound produced by the faulty control function is different (or there is no sound at all), then the fault lies in the transmitter. Look for faulty switch contacts and if these are OK, check the encoder IC. If, on the other hand, the sound produced is similar to that produced when the other buttons are pressed, the fault probably lies in the receiver. 70 SILICON CHIP The result is a flat passband from 300Hz to 3kHz with 12dB/octave slopes on either side of the passband. IC1d buffers the output so as not to distort the signal when loaded. IC1 is a TL074N quad op amp but an LF347N op amp will work just as well. Darren Yates, SILICON CHIP. in the Tri-state condition. Rl serves as a pullup resistor, and the LED is off. However, when the IC does detect infrared radiation, its output goes to logic low. This allows the LED to turn on, to provide a visible indication. Power for the circuit is provided by a 9V battery. To use the detector, ensure an unobstructed path between the IC and the transmitter or infrared source you are testing, and keep the distance between them to 5cm or less. Switch on the detector and operate the transmitter. The LED will light if an infrared signal is present. Bill George, Deception Bay, Qld. ($15) Editor's note: this device is intendecl for detecting infrared signals which are modulated at 40kHz. Unfortunately, most infrared remote controls operate at around 2kHz and would be rejected by ICl 's internal filter. Of cause, the detector may detect a signal from remote controls at very close range if the filter is swamped with excessive signal. D1 1N4004 D4 1N4004 S2a IN + 4700 35VWI LED1 ON 7805 2200 + 16VWJ GND 01J .,. OUT o---<)+V 01+ .,. A ~ rov 240VAC 100k 1% 100k 1% N E~ D3 1N4004 4700 35VW+ o,l If you need a dual-rail tracking power supply in a hurry, then take a look at this circuit. It uses junkbox parts only and can deliver voltages up to ±15V and currents up to 150mA. The transformer is a 22V 1.5A centre-tapped type with diodes D3 and D4 acting as half-wave rectifiers to provide unregulated supply rails of about ±22 volts DC, each filtered by a 4700µF capacitor. 79 os OUT 0--0-V D2 1N4004 202 15V Bare-bones dual power supply S2b 0 IN These unregulated DC outputs drive two 3-terminal regulators, 7805 & 7905. Zener diodes ZDl and ZD2 provide ±15V supply rails for ICl, a TL072 dual op amp. ICla is connected as a voltage follower. Its non-inverting input monitors the output voltage of the 7805 5V regulator via lO0kQ pot VRl. By using the pot to vary the voltage on the COM pin of the 7805, we can thus vary the positive output voltage. Tracking between the positive and negative regulators is provided 2200 16VW:r by IClb which is connected as an inverting unity gain amplifier. This op amp inverts the voltage at the GND terminal of the 7805 regulator and applies it to the GND terminal of the 7905 regulator to obtain the negative rail. Diodes Dl and D2 provide both regulators with protection against reverse voltages which may come from external loads, while DPST switch S2 provides the load switching. Darren Yates, SILICON CHIP. r--------------------------------------• I I SILICON CHIP BINDERS I I I I I I I I These beautifully made binders will protect your copies of SILICON CHIP. Made with a distinctive two-tone green high-quality vinyl and with heavy board covers, each binder holds a year's issues (the 14 issues of Volume 1 or the 12 issues of subsequent volumes). To order your binders, fill in the coupon on the last page of this issue and send it to SILICON CHIP, PO Box 139, Collaroy Beach, NSW 2097. Alternatively, phone (02) 979 5644 and quote your credit card details, or fax your order to (02) 979 6503. Price $Al 1.95 plus $A3 each for postage and packing (NZ $A6 p&p). I I I I I I I I ~--------------------------------------· APRIL 1991 71 Two new 100MHz oscilloscopes from HP Hewlett Packard has done the unthinkable released its latest 100MHz digital sampling oscilloscopes with a host of new features but at a price which directly competes with analog CRT readout scopes. By LEO SIMPSON Until now, digital sampling oscilloscopes have been neither cheap or easy to use. Their controls have been generally quite different from those on conventional analog CROs and their price has usually been a lot higher. Now, with the release of the 54600 series oscilloscopes from Hewlett Packard, all that looks set to change. The immediate difference between these new models and previous models fro m the company is that the con- trol lineup is greatly simplified. Not only that, it bears more than a passing resemblance to the control layout on a conventional analog instrument. For example, there are knobs for vertical attenuators, timebase, trace position and trigger level. None of these knobs have any calibrations though, as their settings are shown in the comprehensive CRT display. The knobs work in exactly the same way as those on any analog CRO and their response is instantaneous. This is quite different from typical digital sampling oscilloscopes (from HP) which have a large number of display modes but which require the user to step through a number of keystrokes and screen menus in order to get the wanted display. Autoscale button The best control feature of the lot is the AUTOSCALE button. This takes all the frustration out of getting a useful signal display on the screen. This can be a time-consuming chore even on analog scopes. On the HP 54600 series, all you have to do is connect the probe to a signal source, push the AUTOSCALE button and the signal is locked on the screen, together with the vertical attenuator and timebase settings. Dead easy. Unlike analog scopes, the new 100MHz scopes display their waveforms brightly and steadily regardless of sweep speed. They do not exhibit the flicker or flare that occurs with analog scopes when displaying signals at very low sweep speeds. Instead, they show a trace of constant brightness, which is gradually retraced, to give the user a visual cue of the low trace speed. Also, the faint traces in highly magnified delayed sweeps can be viewed without the viewing hood required with analog scopes. A peakdetect feature enables the new instruments to display complex waveforms, such as amplitude modulation, correctly. It will catch and display any glitch that is more than 50ns long, regardless of the sweep speed settings. Waveform measurement While it is a digital sampling oscilloscope, HP's 54600 behaves very much like a conventional analog instrument albeit with full CRT readout, electronic graticule and good intuitive "feel". 72 SILICON CHIP The new scopes have the non-volatile storage and waveform-measurement capabilities that only a digital sampling system can provide. With the scopes' two trace memories, signals can be acquired and retained Seen here is the HP54601A, the four channel version of the new 100MHz oscilloscope. It is a very compact instrument with a large screen and easy to use controls. indefinitely. This allows the user to make measurements, compare a previously captured signal with a current one, print hard copies or transfer the data to an external computer for further processing. Pre-trigger viewing Storage also allows pre-trigger viewing by retaining waveform activity that occurs before the trigger event. For example, after triggering the scope on a failure mode in the device under test, a user can look back in time to view the events that caused the failure. This is impossible in an analog scope. AUTOSTORE mode displays the current waveform at full brightness, while all previous sweeps are retained on the display in half-bright, infinite persistence. With this feature, the scope can capture infrequent deviations that otherwise would require constant observation by the user to determine whether deviations occur. The design of the new scopes is based on a new digital architecture developed by HP. Because the instruments use custom IC processors for acquisition and display, they do not rely on the system's CPU to perform acquisition and display management functions. For users , these dedicated processors mean the new scopes have display-update rates as fast as those of analog instruments. Key features of the new oscilloscopes include the following: 100MHz rep.etitive bandwidth on both the vertical and horizontal axes; 2MHz single shot bandwidth; 2ns/ div to 5s/div range on both main and delayed timebases; mV/div to 5V/div vertical sensitivity; 8-bit vertical resolution; automatic setup with a single keystroke; simple one-button display storage operations; 16 front-panel setup memories; two trace memories; edge, line and TV triggering; 12 auto- matic measurements of frequency, time and voltage; dual cursors for accurate manual time and voltage measurements ; pushbutton hardcopy output to plotters and printers via optional parallel, RS-232 or HP-IB (IEEE-488) interfaces. Dimensions are 360mm wide, 180mm high and 300mm deep and weight is 6.4kg. The 54600 series scopes come with a 3-year standard limited warranty with an option for a 5-year limited warranty. Prices are as follows: HP 54600A 2-channel 100MHz oscilloscope, $2,395; HP 54601A 4-channel 100MHz oscilloscope, $2,895; HP 54650A HP-IB interface module, $475; HP 54651A RS-232C interface module , $475; HP 54652A parallel interface module , $275. These prices do not include sales tax. We hope to do a detailed review of the 54600 series in a future issue. In the meantime, sales information can be obtained by calling Hewlett-Packard's customer information centre on (008) 033 821. SC APRIL 1991 73 COMPUTER BITS BY JENNIFER BONNITCHA Playing with the ANSI.SYS file This month, we take a close look at the enhanced keyboard and display device driver - ANSI.SYS. This is an extensive list of codes for driver controlling your monitor screen and keyboard. ANSI.SYS is a driver which causes your computer to emulate the American National Standards Institute (ANSI) standard for terminals. Together with the International Standards Organisation (ISO), these bodies originally established an extensive set of console control codes for terminals connected to mainframe computers. The standards provide software portability for hardware interfaces. Note that ANSI.SYS is not a full implementation of the Digital Electronics Corporation (DEC) terminal VT-100 control codes. While the VT100 terminal implements all ANSI control codes, the DOS version of ANSI.SYS lacks the VT-100 terminal codes to: • erase from the current cursor position to the end of screen. • erase from current cursor position to the beginning of screen. • erase from current cursor position to the beginning of line. ANSI.SYS recognises a subset of the control codes defined in the ANSI console standard. Before you can start experimenting with installable device driver ANSI.SYS, you must explicitly configure your system. The driver needs to be somewhere on your boot disc, although it is usually found in the root or DOS directories. If your driver is in the root directory, include the following statement in your CONFIG.SYS file: device=ansi.sys However, if your driver is located in another directory (typically the DOS directory), include this statement: device=c: \dos \ansi.sys Once you include the driver, you must reboot your system for it to take effect. It remains installed until you remove the device line from your CONFIG.SYS file and reboot the computer again. Technically, ANSI.SYS is a console device driver. It oversees the actions of the keyboard and screen which are collectively known as the console. The program was introduced with MS-DOS 2.0 and has some 15 sepa- Before you can start experimenting with ANSI.SYS, you must configure your system. The driver needs to be somewhere on your boot disc, although it is usually found in the root or DOS directories. 74 SILICON CHIP rate functions which can be grouped into five categories: • control of cursor position; • erase all or part of the display screen; • control video mode settings; • control video attribute setting; • reassign character strings to individual keys on the keyboard. Data entered from the keyboard is sent to the computer as a sequence of ASCII (American Standard Code for Information Interchange) characters. ANSI.SYS operates by intercepting special codes sent to the video display and using them to change how the display and keyboard function. ANSI.SYS then recognises certain character sequences as being command sequences which can direct modification of the display screen output. All ANSI commands have the same format; the command is introduced with an escape character and a left bracket. You will often find the word ESC shown in reference manuals to represent the escape sequence. An ANSI escape sequence is a series of characters that you can use to define functions for MS-DOS. Specifically, you can change graphics functions and affect the movement of the cursor. All ANSI.SYS command sequences begin with an escape character whose ASCII value is 27. The escape character doesn't display on the screen, however you will usually see a left arrow or A(. Either way, ASCII character code 2 7 is the escape character and not the Esc key on your keyboard. The escape character and the left bracket are usually followed by a parameter, although there are some escape sequences which can have multiple parameters and some that don't require any at all. You can specify multiple parame-· ters by separating them by semi-colons. Each sequence ends with a letter to indicate the instruction and terminate the sequence. If the function requires any parameters, they are entered between the [ and the letter. A typical ANSI code, Esc[2J is the clear screen instruction. Note that the function code letter is case sensitive - you need to be careful. ANSI.SYS escape sequences The numeric ANSI sequences have three functions: • to represent the co-ordinates or number of columns or lines to move for cursor positions; • to represent the mode (such as the 2 in Esc[2J - the clear entire screen command) for erasing the display or screen settings; • to represent the ASCII character of the extended code for a key when reassigning the keyboard keys. ANSI.SYS & cursor position The most popular use for the commands is to control the cursor's screen location. Although cursor control is limited from the DOS prompt, you can use this type of command in batch files. You could clear the screen then position the cursor in the centre of the screen. Note the appropriate case for each function code letter. Cursor position - ESC[#;#H - Moves the cursor to a position on the display screen specified by the # parameters. The first parameter specifies the line number, the second the column number of the cursor position. The cursor moves to the home position - upper left corner of the screen - if none is specified. ' Horizontal/vertical position - ESC [#;#f - Has the same function as the cursor position command. Again, with no parameters specified, the cursor moves to the home position. Cursor up - ESC[#A - Moves the cursor up a number of lines without changing columns, where # determines the number of lines moved. The default is 1. If the cursor is already on the top line, MS-DOS ignores the sequence. Cursor down - ESC[#B -As for ESC#A with the cursor moving down the screen. If the cursor is already on the bottom line, MS-DOS ignores the sequence. Cursor forward - ESC[#C - This se- quence moves the cursor forward one column without changing lines. The # sets the number of columns moved, where the default is 1. If the cursor is already in the far right column, MSDOS ignores the sequence. Cursor back- ESC[#D -As for ESC[#C and the movement is backwards. If the cursor is already in the far left column, MS-DOS ignores the sequence. Save cursor position - ESC[s - Saves in memory the current position of the cursor. Cursor position is then restored using the following command, Restore Cursor Position. Restore cursor position - ESC[u - This sequence restores the cursor position to the value it had when the console driver received the Save Cursor Position sequence. Device status report - ESC6n - Requests that ANSI.SYS issue a cursor position report. Cursor position report - ESC[#;#R Reports the current position of the cursor. The first parameter is the current line, the second the current column. ANSI.SYS issues this report in response to the request for a Device Status Report. Erase display - ESC[2J - Erases the entire display and positions the cursor at the home position. Erase line - ESC[K - Erases from the cursor to the end of the line, including the cursor position. There's much more but perhaps the obvious has emerged - how to send the ANSI commands to the screen? You can't just type the escape character, since when DOS interprets the Esc key it means erase this line and start over. Fortunately, you have several alternatives. The DOS TYPE command • create a text file using an editor which lets you enter the escape character just by pressing Ctrl [ (note that it may appear as either a left arrow or A[). You can then use the DOS command TYPE to display the file and activate the functions. A good trick to remember is that the escape character is actually Ctrl V (AV). EDLIN, the DOS line editor, is quite happy to receive this key sequence. The Ctrl V tells EDLIN to make the next character in the sequence a control character. Thus, to enter an escape character, use AV[ followed by the required sequence; {ONI 50 MHz Frequency Counter Kit $ 99.00 1 GHz Frequency Counter Kit $299.00 121240V 40 Watt Inverter Kit $ 99.00 121240V 300 Watt Inverter Kit $379.00 Discolite Kit $159.50 Gates 2V 2.SAH's D Cell $ 7.95 Gates 2V SAH's X Cell $ 11.95 Arlec 6V Lantern Battery with 240V charger & 12V Cigarette lighter charger $ 59.00 Arlec variable Power Supply 5-15V DC 2A $ 89.95 100meter Roll Speaker Cable $ 16.95 President AM 40Channel CB Radio $109.00 4 Channel Audio Mixer for VCR's Arista AVM-1 $ 69.95 13.SV 7.4A Transformer $ 16.95 18V 6A Transformer $ 39.95 200 channel handheld scanner 66-88MHz, 118-174MHz, 406-512MHz, 806-956MHz. $499.00 NOW OPEN our new: Electronics Disposal Store 27 The Mall Sth. Croydon, Vic, 3136 Telephone: (03) 723 2699 Please Note: We are interested in purchasing your Surplus components & equipment. M, n Electronic World 30 Lacey St, Croydon VIC, 3136. Telephone: Fax: (03)723 3860 (03)723 3094 (03)725 9443 APRIL 1991 75 TABLE 1 SPECIFY THIS CHARACTER $ b d e g I n p V TO GET THIS PROMPT The $ character The I character The current date Escape character (ASCII code 1b hex, 27 decimal) The The The The The > character < character default drive working directory of the default drive current time The DOS version number Carriage return, linefeed sequence. Note this is the underscore character eg, AV[[1;37;44m. You must use the double square brackets [[ since the first is used with Ctrl V to create the escape character and the second is the normal lead_-in sequence for the ANSI command sequences. When complete, TYPE filename to see the results. The DOS ECHO command • create a batch file using the above methods to enter the escape character and then use the ECHO batch command to activate the functions. Type the same command above using: ECHO AV([1;37;44m At the DOS prompt, type 't he name of the batch file then press Enter. The DOS PROMPT command • you could use the DOS command PROMPT to activate the commands, since the PROMPT code $E is an escape code - and this is possibly the easiest method . Note that the PROMPT codes are NOT case sensitive. Once again, for the same command: PROMPT $e[1;37;44m The PROMPT command lets you change the MS-DOS system prompt using characters and prompt commands to create special prompts. You must precede each character with a dollar sign ($). Table 1 shows the details. The most popular prompt displays the current drive and path followed by the > than sign: PROMPT $P$G. 76 SILICON CHIP Remember that since the PROMPT command can send ANSI command sequences, you can combine the best of both worlds: PROMPT $e[1;37;44m$P$G This tells DOS to change the screen colour display and make the prompt show the current drive and path information. Using BASIC BASIC shelters the user from the operating system and thus intercepts many of the DOS and computer interrupts. The same shelter environment shields the ANSI device driver. You could, however, use compiled BASIC such as QuickBASIC, Turbo BASIC etc. Clever people can use interpretive BASIC (BASIC, BASICA and GWBASIC) together with the DOS command TYPE to print ANSI sequences. For example: OPEN "TEST4.BAT" FOR OUTPUT AS 1 PRINT #1, CHR$(27);"1;37;44m" CLOSE #1 The program can then be used by typing the DOS command: TYPE TEST4.BAT With practice, you can gain valuable experience both with your computer and the ANSI commands. ANSI.SYS escape sequences The main cursor control functions are up (A), down (B), left (D) and right (C). Remember the default is 1, so used without a parameter, each command moves the -cursor one row .or column. You can however specify the cursor position more accurately: ESC[5B ... I'm here This positions the cursor five rows down the screen, while: ESC[12;35H ... Now I'm here! positions the cursor approximately to the centre of the screen. You could try these commands using COPY CON as discussed last month. As a quick memory jogger, note that each line ends with the Enter key and you press function key F6 or AZ (Ctrl Z) at the completion to copy the console contents to a file: COPY CON TEST.BAT <at>echo off cls prompt $e[5B ... I'm here AZ then COPY CON TEST2.BAT <at>echo off cls prompt $e[12 ;35H ... Now I'm here! AZ MS-DOS 3.3 and 4.x allow you to suppress the display of a line in a batch file by preceding the line with the <at> character. Without the <at> sign, the ECHO OFF command would display on the screen. Thus, the above batch files display only what you need. Remember to separate multiple numeric codes with a semicolon and don't use a semicolon just before the command letter in a sequence. The final letter in an ANSI sequence is the command letter; ANSI does not see this letter if a leading semicolon is used; eg, ESC[44;1;37;m is incorrect. Make sure you use the correct case for the ANSI command letter since upper and lowercase letters are significant. Finally, if you omit a numeric parameter, the assumed value is O (zero) or 1. Depending on the sequence used, ANSI makes various assumptions about missing values. The assumed value for cursor positioning is 1, while for screen attributes it is 0. Be aware that in some situations the default value may not work and yet in others will work correctly. If you omit the row and column co-ordinates from the ESC[f command, ESC[1;1f (the home location) is assumed. Next month, we'll have more adventures with the PROMPT command, setting screen colours and customising the keyboard. 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DEALER ENQUIRIES WELCOME TRY PC MARKETPLACE SUPERFAST MAILORDER - PHONE OR FAX TODAYI Plii[ yfeeson s PERSONAL COMPUTER MARKETPLACE PtyUd FREIGHT CHARGES PHONE (02) 418 6711 Include $10 with order for all normal items • heavy items, e.g. monitors add $15. FAX (02)4186713 14 day money back guarantee Mail Order Address: Order by phone (use credit card), by fax or by mail. P.O. Box 1100 Lane Cove Unlesa insurance is declined it will be charged at 1% oftotal purchase. This is for your protection. NSW2066 PRICES CURRENT FOR MONTH OF PUBLICATION OR WHILE STOCKS LAST. 0 e SER.VICE IS THE DIFFER.ENCE e SER.VICE IS THE DIFFER.ENCE e SER.VICE IS THE DIFFER.ENCE e SER.VICE IS THE DIFFER.ENCE AMATEUR RADIO BY GARRY CRATT, VK2YBX The Easytune FSK indicator for HF transmissions This project was born out of the frustration of trying to tune various HF data transmission modes. Initially, the problem was trying to correctly tune an HF receiver to allow the use of an automatic CW decoder. Our problem was that we could hear these signals but couldn't decode them. RTTY? Obviously, a switched multitone box was out of the question. As most RTTY stations feed AFSK tones directly to the transmitter from a modem, decoding the two tones, the mark and the space, had to be achieved simultaneously. This is also the case with fax and packet radio transmissions. While old timers will no doubt be shaking th eir heads in dismay, it is a sad fact of life that not all amateurs are skilled in the reception of CW. Knowing this, various manufacturers produce equipment that is able to deco de machine generated CW signals. The device we were using to decode CW signals called for an audio input of 800Hz plus or minus 80Hz. It incorporated both an active filter and a PLL filt er, driving a CPU and associated software, which in turn produced decoded text on a 2-line liquid crystal display. As any newcomer will The next consideration was a visual indicator. We needed a circuit that would activate a LED when the correct tone or tones were received. A quick check in the data book reveal ed that an LM567 would do the trick nicely. We had seen circuits for tone decoders using the 567 before but most gave few details. Fig. l(a) shows the circuit we built, which worked perfectly first go. The 567 is purpose designed for this task. Fig.2 shows the internal details of the 567 tone decoder. It contains a highly stable phase locked loop with synchronous lock detection and an output driver. The centre frequency, bandwidth and acquisition time are all determined by external components. Basically, there are only three components that determine the operating characteristics of the device. Rl and Cl determine the operating frequency of the internal PLL. C2 determines both the speed and bandwidth of the device. As can be seen from Fig.3, the 567 has a maximum detection bandwidth of 14%. Using this figure, the value of C2 can be determined from the graph. In our case, we wanted maximum bandwidth detection, so C2 is lµF. We found that any value greater testify, accurately tuning the receiver to produce an audio output of 800Hz without any audible or visual reference takes some finite time, enough to miss parts of the transmission. What was needed was some kind of indicator. Initially, we pondered the use of a fixed 800Hz oscillator driving a loudspeaker, and housed in a small plastic box. It should be simple enough to hear the beat difference in output fre quency and adjust the receiver accordingly. This would have been fine if CW was all we wanted to listen to . But what about facsimile, packet and 120!1 r------ -+- - -+-- - ~~Mh-0 +1 2-15V + 100 16VW+ LE01 201 8.2V J .,. AUDIO 0. 47 INPUT o---1 3 IC1 567 .,. VA1 22k + 1+ + 1+ Fig. l(a): this single tone version of Fig.1 can be used for tuning into CW transmissions where connection to an automatic Morse decoder is required. 78 SILICON CHIP IC tone decoder 120\! 100 PARTS LIST + LED1 16VWJ 1 PC board, code SC06104911, 77 x 50mm 2 22kQ trimpots, (VR1, VR2) 2 1kQ 0.25W resistors IC1 567 Semiconductors 2 NE567 tone decoders (IC1, IC2) 2 red LEDs 2 8.2V zener diodes (ZD1, ZD2) 120!! .,. VR1 22k ~t 1 AUDIO ,.____ INPUT ~ 100 + Capacitors 2 100µF 16VW electrolytic 2 2.2µF 16VW electrolytic 2 1µF 16VW electrolytic 2 .068µF metallised polyester (5mm lead pitch) 2 .01 µF monolithic or metallised polyester (5mm lead pitch) ZD2 16VWJ: 8.2V IC2 567 FSK TUNING INDICATOR Fig.l (b): this is the version of the Easytune Indicator circuit for FSK detection. The two 567 tone decoders are set up to indicate the two different FSK tones. than lµF caused the unit to be too slow in driving the output. By op erating the chip in the "high input level" mode (ie, more than 200mV of input sign al), th e bandwidth chan ges caused by input signal variation are eliminated; however, the chip then becomes sensitive to sub-harmon ics, as th e input stage w ill be limiting. By operating the chip in the "low input level " mo de , best n oise reduction an d out-of-band signal rejection is achieved, so we determined that feed ing the input from a low level source would be the best option. C3 sets th e b nd edge of the inter- PHASE DETECTOR I R2 C2 LOO P LO W- PA SS FILTER _ 3.9k R1 CURRENT CONTROLLED OSCILLATOR Other data modes Having sucessfully overcome th e CW tuning problem, we began to think of the other interesting HF data +V INPUTD---"f-.._--l V1 n al low pass filter which effectively attenuates frequen cies outside the detection band to eliminate spurious outputs. Th e device is fe d via a 9 volt zener regulated supply for temperature stability. This also ensures that the maximum DC voltage of 10 volts is never exceeded . The output, pin 8, is the coll ector of an internal trans istor which saturates w h en an in-band signal is received, an d can sink 100mA if necessary, although not in our application. We used the outpu t to drive a LED, which is our visual indicator. ~ :.! 100kt----'t---t--- I --+---< ;;, +---+---+---+----l u +V R3 QUADRATURE PHASE 1 -......-----1 DETECTOR RL 0 ~ ~ 5:,: 10k t---t---r"'~r"'~t---t---t-----i ~ Vrel 1k .___..___..___..___..___..___.._____, 0 C3 10 12 14 BANDWIDTH (%lo) 0/P FILTER! as Fig.2 : inside the 567 tone decoder IC, made Signetics, National Semiconductor and a number of other companies. It contains a phase lock loop and a lock detector (pin 8). Fig.3: the 567 has a m aximum detection bandwidth of 1 4 %. Using this figure, the value of C2 can be determined from the graph. In our case, we wanted maximum bandwidth detection , so C2 is lµ F. APRIL 1991 79 f[ C ,,J r.. ,J J l~ r 300 I 1070 1170 1270 F1S le F1M 300 387 2025 2125 2225 F2S le F2M FREQUENCY (Hz) 3300 ,) J 1200 MARK 2200 SPACE 3300 FREQUENCY (Hz) Fig.4: this diagram shows commonly used tone pairs for FSK transmissions and their respective standards. modes. HF packet at 300 baud, for instance, uses two tones, 1070Hz and 1270 Hz, which comply to the Bell 103/113 standard. At VHF, the Bell 202 standard predominates 1200 baud operation and uses 1200Hz and 2200Hz. So we proceeded to build another tone decoder, feeding both units with common audio and power. Fig.1 (b) shows the circuit details. Construction A small PC board has been designed for the FSK Tuning Indicator shown in Figl(b) and this can also be used for the circuit shown in Fig. l(a). Fig;5 shows the wiring layout on the PC board. Install all the parts as shown, taking care to ensure that all . '(}~ The PC board can be mounted inside the equipment or installed in a separate case. Power can come from a 9V battery, via an on/off switch. polarised components are correctly oriented. By pre-adjusting one decoder to each tone, it became a simple matter to tune the HF receiver, so that both LEDs were illuminated when the correct tones w ere being received. Fig.4 shows commonly used tone pairs and their respective standards. Alignment is easy. Conn ect a suitable audio frequency counter to pin 5 of the 567 and , ensuring that there is no audio input connected to the circuit, adjust VR1 until the desired frequency (the same frequency we wish to detect) is displayed. No doubt the same technique can be used for other tone pairs, used for packet, RTTY and Fax. The unit could be built into a receiver or enclosed in a plastic box and fed from the headphone socket of the receiver. Our unit needed lO0mV to op erate correctly and this level is easily achieved through the headphone socket. In some receivers, it may be possible to us e the external record socket, which provides a fixed level of audio, regardless of the volume control setting. This was the case on our Yaesu FRG7700 lab receiver. The unit could be powered from a 9 volt battery but as the current drain is around 20mA, an on/off switch is recommended. This is no inconvenience, as once the signal is tuned, only periodic ch ecks are required to monitor receiver drift. References Signetics Linear LSI Data and Applications Manual, 1985; CQ Magazine, January 1991; The ARRL Handbook. SC 2.2ue uF17 0 ~ LE °'u u• C . AUDIO INPUT +12· 15V + GNO + Fig.5: this is the PC hoard wiring diagram for the FSK versions of the Easytune Indicator. A single tone version can be built by leaving out all the components associated with IC2. 80 SILICON CHIP Fig.6: this is the full size artwork for the PC board. I PRODUCT SHOWCASE I Flying-H antenna has large reflector AT motherboard rated at 21MHz This attractive AT motherboard has all the features that most 286 computer users could want. It has a 16MHz zero wait state CPU .(21MHz landmark speed rating), three 16-bit and three 8-bit expansion slots, two serial and one parallel printer port, a Dallas real time clock and an IDE 40- Amp-hour meter for lead acid batteries With the increased interest in storage batteries for solar power and electric vehicles, there is now a growing number of applications for this amp-hour meter from Av-Comm Pty Ltd. Based on a microprocessor, the unit counts the amp-hours drawn from a . battery and displays them with a minus sign. As charging begins, amp-hours are added until the display reads zero. It automatically compensates for charging efficiency and can be zeroed after a battery is overcharged. pin connector for a hard disc interface (for adding an embedded hard disc drive). It also has an onboard floppy disc controller and can take up to 4 megabytes of RAM. The only thing you need to install on the motherboard is a VGA card. The price? Just $595 from Rod Irving Electronics, 74 Parramatta Road, Stanmore, NSW 2048. Phone (02) 519 3134. Battery current is sensed with a precision shunt and it can handle currents up to 200 amps. For further information contact Av-Comm Pty Ltd, PO Box 386, Northbridge, 2063. Phone (02) 949 7417 or Fax (02) 949 7095. This unusual UHF antenna has an H-section dipole backed by a reflector to increase the gain. Claimed frequency coverage is from 420MHz to 960MHz (ie, band 4 and 5) and the unit can be mounted for reception of vertical or horizontally polarised signals. The construction is mainly of black UV-stabilised plastic with clip-in black anodised aluminium rods for the rear reflector. It has an inbuilt balun and an American style 75Q coax connector. It is available from all Jaycar Electronics stores (Cat LT-3180) for $49.95. Unit converts PC signals to PALINTSC Chromatek Advanced Video Laboratory has released the model 9120, a real time Scan Converter which converts video signals from personal computers to broadcast quality PAL or NTSC signals. The scan frequency range is from 15kHz (CGA) to 128kHz (high resolution screens). This enables computer generated graphics to be used for broadcast video sources. The video input signals are measured automatically by the 9120 and if necessary, it adjusts the conversion APRIL 1991 81 to achieve the best picture quality. This allows the user to convert computer images to standard video tape without having to know the computer's video specifications. Besides the composite signal for NTSC or PAL, the 9120 has outputs for RGB, Y, R-Y luminance/colour difference signals, and the Y/C signal for NTSC. Included as standard features are a montage circuit for making composite pictures, a gen-lock circuit for phase matching studio sync signals and a comb filter for colour cross checking. Functions such as chroma keying, D-1 output and test pattern generators are also available as options. For further information, contact Anitech, 52/2 Railway Parade, Lidcombe, NSW 2141. ATTENTION AMATEUR ASTRONOMERS 4-channel digital recorder/announcer Back in December 1989, SILICON CHIP published a Digital Voice Recorder Board which caused a great deal of interest at the time. All sorts of organisations used the basic design presented there to develop audio storage units to suit their own applications. One such product is the Harris 4channel digital recorder/announcer. It is developed considerably from the original project and has 4 megabytes of dynamic RAM to substantially increase its recording time and/or qual- ity. It can record 4 messages each up to 30 seconds. Also included in the unit is a timer whereby the messages will be automatically played at intervals ranging from every three minutes up to 30 minutes. It is intended for applications such as music on hold, store or phone announcements, security announcements and PA system feedback eliminator (in instant replay mode). Recommended retail price is $799.00. For further information, contact Altronics Distributors Pty Ltd, 174 Roe Street, Perth, WA 6000. Phone (09) 328 2199. We import and sell by Mail Order all types of Telescopes and Accessories suitable for astronomical observation and astrophotography. Because of our vast experience in visual obervation and astrophotography, we can best help you to select the right astronomical equipment. That is, equipment that suits your individual needs and budget. Furthermore. we do not recommend a given product unless we have tested it ourselves or haye enough favourable in- formation about it from a reliable source We are glad to inform those who are interested in the very best in optical, electronic and mechanical performance, that we are now the Sole Australian ~ for the world-famous TAKAHASHI astronomical products. We offer our customers a fast and efficient service and we will better any advertised price on astronomical equipment of the same brand and quality. For further information or technical advice contact: ASTRONOMY AND ELECTRONICS CENTRE P.O. BOX45 CLEVE, SA 5640 Phone (086) 282 435 Anytime 82 SILICON CHIP Bose Lifestyle System Winner As announced in the March 1991 issue, Mr Stuart McDonald of Warners Bay won the Bose Lifestyle Music System which was the major prize in our subscription drive last year. Pictured above is Stuart MCDonald (at left) being awarded his prize by Paul Trimble, manager of Charlestown Hifi. Charlestown Hifi is a specialist hifi dealer serving the Newcastle, Lake Macquarie and Hunter regions. Congratulations Stuart. April bargains will save you $ from Sheridan's ARLEC AC/AC ADAPTOR These are 6VAC and 3 Ahr and are approved. What a bargin ONLY $9.95 Travelmate 2000 notebook computer has 286 CPU The Travelmate 2000 is based on a 12MHz 80C286 processor with one megabyte of DRAM (expandable to 3 megabytes). It comes with a 20 megabyte hard disc, a full function keyboard and has a triple supertwist LCD black on white VGA display. The 254mm display uses cold cathode fluorescent side lighting to provide crisp images. It is claimed to be ideal for running Windows or other graphics intensive software. Standard features comprise a Centronics parallel interface, RS-232 serial port and an expansion port. Optional features include a numeric keypad interface, 1.44MB floppy drive and CRT interface. Battery watch software enables the user to check the battery status at any time. Recommended retail price is $5250 plus sales tax where applicable. For further information, contact the Marketing Manager, Data Systems Division, Texas Instruments Australia Ltd, 6-10 Talavera Road, North Ryde, NSW 2113. Phone (02) 878 9000. Spaced out TV from Philips If you're sick of the sameness of today's TV sets with the black rectangular cabinets then consider this new model which is styled in the form of a space helmet and finished in Monza red. Flipping up the visor reveals a 14-inch dark glass screen. It has an on-screen digital display to show control functions such as programming, volume, picture and timer. It comes with an infrared remote control, also finished in Monza red. The set may be viewed with the visor up or down and may be tilted for the best viewing angle. The price of this piece of whimsy? $699 from your nearest space appliance store. SC 8 LINE DOT MATRIX DISPLAY Included with this display is the driver necessary and also a data sheet to get you started. There is only a limited quantity so be quick ONLY $39.95 ELECTRO$ 4.5" 230/240V FAN Ball bearing type These come in three types 2200uF 35V $1.20 each These are quality new fans and 10,000uF 16V and the 470uF 200Vare only $2.50 each only $14.50 These quality Hitachi displays come complete with the driver and have a 128 x 480 dot matrix display. Uses LM215 ~ Includes data sheet OUR PRICE $45.00 -· "' - Mi;~"" lllllsr <, Mlnature Toggle switch This one has hundreds of uses and we have a bulk load of them. SURRY HILLS, NSW, 2010 TELEPHONE: (02) 281 7727 . "' ~" ::1 These can be used in mains filter projects and have a rating of 5 AMP, 50/60Hz. Grab a couple just in case. ONLY $2.95 I SHERIDAN ELECTRONICS, 328 ELIZABETH ST, . (Cnr Klppax St. opp. Central Station & Dental Hospital) < Potter 250V Mains Filter 10 FOR $6.00 While stocks last ,~ Ud SHOP HOURS: MON-FRI SAT 9.00am- 5.30pm 9 12 .30am • .00pm APRIL 1991 83 . ~ \\ . 2&4WAY RS232 DATA TRANSFER SWITCHES If you have two or lour compatible devices that need to share a third or fifth, then these inexpensive data t~ansfer switches will save you the time and hassle of constantly changing cables and leads around. • No power required • Speed and code transparen1 • Two/Four position rotary switch on front panel • Three/Five interlace connections on rear panel • Switch comes standard with female connector THl;:BUTTON SPIKE PROTECTOR Surges and spikes are caused not only by lightning strikes and lo_ad switching but also by other equIpmen1 being switched on and off , such as fluorescent lights, electr!c motors, fridge freezers, air cond1honers, etc. A simple way of monitoring RS232 interface lead activity. Interlace powered, pocket size for circuit The Fortran CPF Filtered Electronic Spike Protector provides a protective electronic barrier for microcomputers. printers. telephone systems and modems electronic typewriters, audio and stereo systems and other sensitive electronic equipment. The CPF provides protection from dangerous electrical spikes that can cause anything from obvious damage (like immediate equipment failure) to less obvious harm that can drasticaUy shorten a system's life. CPF's superior circuitry design and semi conductor technology responds instantly to any potentially damaging over-voltage, ensuring safe trouble free operation. , Additionally. CPF's filtering capability helps elimmate trm •blesome and annoylng interference, general hash cre_ated by Small motors, fluorescent lamps, and the like that threaten the performance and shorten equipment life of unprotected electronic components. SPECIFICATIONS: Electrical rating: 220-260 volts (AC) 50Hz 10 Amp Spike/RF! Protection: 4,500 amps for 20m/second pulses Mavlmum clamping voltage: 275V · ditferemti:ti mode. Cat.X10088 ........ $69.95 \~~~~arg:~~j~9 ~~g~a~~~ing. 2 spares 24 switches enables you to break out circuits or reconfigure and patch any or all the 24 active positions. For effective protection such spikes must be ~topped b_efore they reach ~~;o~9~~~~~J!~f~~~ ~Tn~~~tect 1 SPECIFICATIONS: Connectors: 0825 plug on 80mm ribbon cable and 0825 socket Indicators: Tricolour LED's for TD . AD, RTS, CTS, OSR, CD, TC all equipment plugged into a~1acent outlets on the same branch circuit The Button employs unique metal oxide varister technology and will dissipate 150 joules of electrical energy. (nearly twice that of comparable surge arresters.) AC. DTR, (E)TC . Jumper Wires: 20 tinned end pieces Power: Interface power. Enclosure: Black, high impact plastic Dimensions: 85 x 95 x 30mm ..... $42.95 _ _ ___ _ _______ _ __ , Q ·... . COMPUTER PAPER Quality paper at a low price! 2,000 • $39.95 -~ I I 1' 1l ROD'S COMPUTER Jl TIPS! UV EPROM ERASER Erase your EPROMs quickly andsafely. This unit is the cost effective solution to your problems. It will erase up to 9 x 24 pln devices in comp.lete safety, in about 40 minutes (less time for less chips) • Chip drawer has conductive foam pad • Mains powered • High UV intensity at chip surtace ensures EPROMs are thoroughly erased !Are you having trouble KEYBOARD EXTENSION LEAD : reading 5 1/4" disks which I have been around your • Keeps your paper and prmt-outs· 5 Pin Din plug and socket . I children or non-computer neat and orderly P19038 ................... $9.95 : people? This is a common • Transparent cover makes 11 easy to check on paper supply fingerprint problem. Arm • Paper can be fed from the centre or the rear according to the design 1 yourself with a bottle of of the printer 1 methylated spirits and • Removable drawer which allows paper to be changed without cotton wool balls. Hold the Without timer moving the printer • Retractable rear basket makes disk that wont read up to X14950 ..................... $99 print-out collection fast and convenient the light and try and spot With built-in timer • Suitable fo r mos1 printers the fingerprint, grease or . X14955 .................. $169 $69.95 foreign matter. You do this by looking in the "window·• DUST COVERS DELUXE PRINTER STAND at the media and slowly I • ~~~~~~~i~~~~i~l~~t~:~~~i;ea turning the disk with your : nd • ~;;g;iit~~;~'t~~sa~~~1f;.u er fingers in the middle hole. I • Adjustable paper deflectors Be v~ry careful not to : 0 ;i;;tFcaper crease the disk. You might I 0 ~;~::~~~ ~ 7uo~~~rinters$ 1 0 69 _95 have to clean both sides of ; DATALIFE DL-600 ~ the disk at the problem I DATA CARTRIDGE position(s), but normally 1 Stores up to 120 M/Byte you can recover your 1 C12614 ............. $59.00 software by this DUST COVER 1 ENCLOSED PRINTER STAND j ·,, only$49 onlY$59 2WAY {X191 sheets of 70 gsm bond paper ~ Star, and many other printer ~N~u~~~~e::quired • Speed and code transparent • Two/Four position rotary switch on front panel • Three/Five interface connections on rear panel • Switch comes standard with female connector • Bale locks are standard . Cal. C21003 11 x9 112·· $39 $49 Save time·and hassles of constantly changing cables and leads around with these inexpensive data transfer switches. These data switches support the 36 pin centronic interlace . used by Centronics, Printronics, Data Products, Epson, Micronics. ~6:~~lt~ir!~VR~~~tf~o Joules Response Ti me : 1Ons Protection Level : 350V peak r' only only 2&4WAY CENTRONICS DATA TRANSFER SWITCHES SPECIFICATIONS: X15700 .............. $99.95 g 2 WAY Cal.X19120 4 WAY Cal.X19125 XT HD CONTROLLER ...,$1 29 AT HD CONTROLLER .... $199 RS232/SERIAL CLOCK. ................•..•........ $49 MONO COLOUR CARD .• $76 MULTI 0~ ......................... $99 512K RAM........................ $59 DIAGNOSTIC........•........•. $795 TTUPRINTER. ................. $89 RAM 2M AT EXT/EXP. ..... $225 SM AT EXT/EXP............... $325 FAX CARD ....................... $595 4 PORT SERIAL ............. $129 VGA 256K ........................ $179 VGA 512K ........................ $219 VGA 1MEG ...................... $249 VOICE MAIL.. .................. $199 PRINTER CARD ............. $29 EGA CARD ...................... $149 • ~~~u;~i5~gi,~:~ 2 WAY FDD CONT (360K) .............................. $39 RS2321SERIAL <:ARD ..... $39 GAMES CARD ................. ~29 AT SIP/G 1 SIPIG ............. $43 AT S/P/G 2 S/P/G ............. $49 4 WAY FDD CONT. (360-1.44M)...................... $129 2 WAY FDD CONT. (360-1 .44M)....................:. $80 CLOCK CARD ................. $39 SMART DRIVE ADAPTER IDEIFDC........ $89 SMART DRIVE AO APTER mE 110 FDC... $119 : •High quality ABS plastic and anti-static rubberised lop •Stationary holder •Includes pull-out sheH for I this problem!!! 1 I Regards Rod Irving. I c 21066 •·················$ 14 ·9 5 .L .________________ .J AT' Cover Set C21068 .................. $16.95 Mouse LEADS RS232 GENDER CHANGERS • Saves modifying or replacing non-mating RS232 cables . • All 25 pins wired straight through Cat X15650 Male to Male Cat. X 15651 Male to Female Cat X 15652 Female to Female 'Normally $14.95 each Onlv$8.95 DISK NOTC:HF.R Converts 5 1/4" single sided noppy disks to double sided , by placing an appropriate notch in the floppy disk jacket. c2107o .................. ss.oo Stanmore. RS232 MINI TESTER • Male to female connections • All pin wired straI1=1hl through • Dual colour LED indicates activity and direction on 7 lines • No batteries or power re quired T.D . Transmit Data D.S.R. Data Set Ready A.O. Receive Data C.D . Carrier Detect A.T.S. Request to Send D.T.A. Data Terminal Ready C .T.S. Clear fa Send Cat. X15656 . . .. Normally $39.95 SPECIAL. ONLY $32.95 2048. Phone (02) 519 3134 Fax (02) 519 3868 MELBOURNE , 48 A·Beckett St Phone (03) 663 6 t 51 NORTHCOTE: 425 High St. Phone. (03) 489 8866 CLAYTON : 56 Renver Rd . Phone (03) 543 7877 MAIL ORDER& CORRESPONDENCE: P.0 ..Box 620, CLAYTON 3168 Order Hotline: 008 33 5757 (Toll free, strictly orders only) Inquiries: (03) 543 7877 Telex: AA 151938 Fax: (03) 543 2648 MELBOURNE DEALERS MICRODOT 177 SPRINGVALE.ROAD NUNAWAOING. Ph.894 1255 GREENSBOROUGH accessories free of dust and -I children I am very aware of I grime while not In use A working bench tor your Mouse. . XT* Cover Set 1 1 Only $24.95 SYDNEY ·: 74 Parramatta Rd. Keep your computer and . procedure. Having young . Normally $33.95, RODIRVING ELECTRONICS l MAGIC STAGE CENTRONICS GENDER CHANGERS • Female to Female. • Saves modifying or replacing non-mating Centronics cables. • All 36 pins wired straight through. Cat. X15663 Male to Male Cat. X15661 Male to Female Cat. X15664 Female to Female H EAD CLEANER DISKS It only takes a minute amount of dust, dirt or magnetic oxide particles on your drive heads to cause problems: errors, downtime or an expensive service call. Regular use of a head cleaner will keep your drive free of trouble causing dirt and help keep your system up and running. These disk cleaners a rc simp le to use, and include cleaning solution and COMPUTERS 97 GRIMSHAW ST (au Howard et) Ph: 434 5116 BRISBANE DEALER VRC COMPUTER SERVICE 647 LUTWYCHE RD . LUTWYCHE, 4030 ADELAIDE DEALER .. CROTROIICS 305 MORPHETT ST ADELAIDE, 5000 instructions. • 3 1/ 2" • IBM· compatible • D837 Male to 34 way edge conneclor • Length 0·5 metres P19045 $99.95 3½" FLOPPY DISK DRIVE EXTENSION CABLE • IBM' compatible • 0837 Male to 34 IDC connector • Lenglh 0·5 metres P19046 $99.95 6 PROTECTED POWER OUTLETS Ideal for protecting personal computers, video equipment, colour TVs, amplifiers, tuners, graphic equalisers, CO players etc SPECIFICAllONS, , Electrical rating: 240V AC, 50Hz, 10A • 3 x Metal Oxide Varistors (MOV) • Maximum clamping Voltage: each MOV: 710 volts at"50 amps • Response time: Less than 25 Nanoseconds. Cl2560 ............ ,..... S6.95 POCKET AUTO AB SWITCHES PRINTER LEAD • Suits IBM* PC/XT, compatibles • 25 pin "O" plug (computer end) to Centronlcs 36 pin plug • Pocket size, auto-scanning • Allows 2 PCs to share one Printer •1.8 metres P19029 ...... ............ $14.95 • 3 metres P19030 .................. $19.95 • 10 metres P19034 .................. $39.95 Serial model: MS-201 - Host-powered X19150 .................. $79.95 Parellel model: MP-201 Protocol transparent X19155 ................•.$89.95 I • ~ \ • , , ' , , ,, , , Cl2555 .................. S6.95 . ~ ' • .:I.. • RITRONICS WHOLESALE. 56 Renver Road, Clayton . Phone: (03) 543 2166 (3 lines) Fax: (03) 543 2648 For postage ratea refer to other R.I.E advertisement ~* RIPPER STRIPPER Remove ugly paper feed edges quickly and cleanly with this simple little gadget C21085 .................. $14.95 X10086 .....................$69.95 \ • .• • · • · • 5 1/4" All sales tax exempt orders and wholesale inquiries to: Errors and omissions excepted. Prices and specifications subject to change. ISM", PC'. xT·. AT·. 1,e,eg,sl!""l!d!rademarksol lrnemetiooal 8uS"1HS Machines 'Appi:e" a registe<ed lrademan. 'Oenoln r€9119f&d trldmatksollhetrrespeciM1own&fs BNC PLUGS AND SOCKETS ' ICSOCKETS HEATSI NK COMPOUND ffiffi Healsink compound is applied to the base and mounling studs ol BNC MALE PLUG 1-9 10 -99 100. P10514 $2.50 $2.25 $1.50 .. H11800 .. 10g .... .. $2.00 H11810 .. 1 ·.c·$14.95 BNC PANEL SOCKET 1-9 transistors and diodes. II maintains a posittlo'e heatsink seal that improves heat transfer from the device lo the heatsink, lhus increasing overall efficiency . P. 10 -99 100. Pi0516 $2.50 $2.25 $1.50 ULTRASONIC BNC CRIMP PLUG 1-9 10-99 11,)(). P10530 $2.95 $2.75 $2.00 ~ BNC SOLDERLESS TWIST ON PLUG 1-9 10 -99 100. Pi 0531 $2.50 $2.25 $2.00 TRANDUCERS Designed to transmit at 40kHz (L 19990) and recieve at 40 kHz (L 19991)wilh up lo 20V burglar alarms, moflon detectors and information carriers aS' !hey can be either L19990..... $3.95 L19991.. .. $3.95 $2.95 $2.95 ffl G:JL:=10+ 100+ P1Clll64 $3.95 $3.50 $2.90 CANNON TYPE 3 PIN CHASSIS FEMALE 10+ 100+ PHIIIM $4.95 $4.50 $3.50 condenser C•I . No. Description Power supply:9V battery Range: 300 feel In open field P105SO P10S60 P10565 P10567 P10568 P10569 Pt0570 P10572 P10575 ,., ,,., ,,. ...... ,so 8 pin 14 pin ....20< t6pin .... 20< t8 pin .... 30< 20 pin .. .. 35< 22 pin .. .. 35, 24 pin .... 35e 28 pin .... 451 40 pin .... 45C: ... '"" RECIEVER SPECS: ,, 150 ,... Aecelver freq: -37.tMHz Output level: 37mV(max) Receiving sys : Super crystal 30< 25< ~~:::~~~~r~l~~~~~g Led 1()< 250 22< 30< 26< 30< 26< 35< 30< 40< 35< oscillation Dimmensions:115x32x44mm Weigh!: 22og,ams wire wra·p sockets are !in-plated phosphor bronze. 1-9 10+ P10579 8 pin 1.50 1.40 P10580 14 pin 1.85 1.70 P10585 16 pin 1.95 1.80 P10587 18 pin 1.95 1.80 P10590 20 pin 2.95 2. 75 P10592 22pln 2.95 2.70 P10594 24 pin 3.95 3.50 P10596 28 pin 3 .95 3.50 P10598 40 oin 4.95 4.50 i- , IDC PLUGS . PCB MOUNTING SCREW TERMINALS ·. : AND ,___ SOCKETS . ~ . devices that need to share a third or fifth, then these inexpencivedata tranfer wilt save youthe time and hassle of constantly changing Cables and leads around . No power required Speed and code tranparent . Two or four position rotary switch on front panel. Switch comes standard with female connector. RS232· 2 way ..................... $39 RS232- 4 way .....................$59 RS232- X over .................... $69 RS232· 2 way auto .............$69 Centronics- 2 way ............ ..$49 Centronics- 4 way ..............$69 Cenlronics- X over .............$69 Centronics- 2 way auto ..... $79 1.. 10+ D TYPE IOC PLUGS 1·9 100+ P111860 $4.50 $3.50 $2.50 COMPUTER CABLES 100. o pin plug $2.95 $2.50 $2.00 • DA15P 15 pin plug P12168 $3.50 $3.00 $2.50 • D825P 25 pin plug P 12 l 70 $4.50 $18$ $3.50 3w1y P12166 SO.BO SO. 70 $0.60 •• - c:=t 10+ 100+ 10 . • OE9P !SO.ISO SO.SO $0.AO , Pt0521 9 PIN TO 25 PIN CONNECTOR ADAPTORS The perfect solution! 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IC SOCKETS ===1.,; ===1~ ,QUALITY 5MM LEDS 1-----------f A10452............... $99 CANNON TYPE 3 PIN LINE MALE 1-9 Transmitting Frequency: 37.1MHz: Transmitting system: Crystal oscillation . Microphone : Eleclret (INTERLOCKING ENDS) ~ 1·9 10+ · Receiver P10962 $3.50 $2.95 $2.50 1-9 MICROPHONE SPECS: SOCKETS Save• small fortune on these '"Direct Import" low prollle le sockets! PCB mounting solder 1111. All tin plated phosphor bronze or berrylllum end dual wipe tor reli•blllty. water level detectors, 10+ 100+ CANNON TYPE 3 PIN LINE FEMALE LOW PROFILE IC These units can·t be heard so are ideal for TV remote control's , ·Transmitter 1-9 1-9 ( CRYSTAL LOCKED WIRELESS MICROPHONE & RECIEVER IIP on !he transmitter. pulsed or used in a continuos wave mode. CANNON TYPE 3 PIN CHASSIS MALE LEDS Errors a , Prices an speci ica change. IBM. pc· xt· AT· ilf9 189'St11, lntem1tion11 Bus ,neu Mach, ,eg,sierld tr l0e/Tll111 • :11dm1nr.sot the,1 respec1ove REMOTE CONTROL BY BOB YOUNG How pulse code modulation decoders were developed Of all the units that comprise the modern radio control set, the decoder has probably undergone the most circuitous development. Where many discrete components were once required, it can now be done in one or a couple of ICs. As I have pointed out in the past, when the new generation of PCM sets were launched onto the marketplace, accompanied with the usual hoopla, much was made of the fact that PCM was fitted with "Fail-Safe". Amid many gasps, oohs and aahs, the unsuspecting modern generation of the modelling fraternity eagerly embraced PCM, as do all fraternities eagerly awaiting their next technological "fix". This appears to be the problem when dreams become reality, the reality fades quickly and a jaded technological palate seems to require constant boosts of new technology. If only people stopped to soak up the wonder of all of this technology we are surrounded with, they would be much more satisfied with what they have. However, not all of the modelling fraternity eagerly embraced PCM. The CLOCK RESET CH1 OUT CH20UT CH3OUT CH4OUT fl____________________.r _Sl___________________ - -n~ - - n _ __ _ ____. .....__ Fig.1: repeated from last month, this diagram shows the essence of the serial to parallel conversion performed in the decoder. The serial pulses from the receiver are converted into control pulses for the servos. 86 SILICON CHIP greenhorns may have, but us old timers recognised it for what it was; a recycled version of the system that by 1964 had become known as "that circuit which neutralised the controls on the way to a crash". PCM has become one of the sad stories in the development of R/C systems. However, I digress. The modern digital proportional system grew by a tortuous process and progressed through all sorts of developmental periods, amongst which were pulsed multi-tone systems. These systems came close to giving good results but the technology for tone decoding did not exist in those days (late 1950s). I still look at the multi-tone system with interest and with the new technology, I feel there is potential for a much more interference free system here. However, that is for the future; our story is about the past. In the early 1960s, Don Mathers and Doug Spreng developed the first really successful digital system and it completely revolutionised model radio control. Gone were the days of constant retuning, bulky audio filters and poor response times. The Mathers and Spreng system delivered tuning-free control with a maximum response time of 16 milliseconds and almost perfect proportional control. The greatest benefit howe.ver was that all controls were simultaneous . Gone were the days of manually pulsing alternate controls. The modellers of the day were in raptures. Here was genuine progress and the marketing men had a field day, and for once I did not mind. I was in there helping them. Real progress I am all in favour of. However, the first generation de- however, and the second generation sets allow the owner to select FailSafe or leave it off. They even allow choice of PPM or PCM modes. The Germans have a quaint way of expressing the situation; they state that Fail-Safe PCM allows you to "crash like a gentleman". If you have one of these modern sets, select PPM and no fail-safe. The results are well worth the effort. Personally, I feel that a more productive approach to PCM and microprocessor systems would be in error detection and correction as in CD technology, leaving Fail-Safe out completely. This would represent, to my mind, a valid application of technology. Circuit techniques The Bonner Digimite was quite advanced for its time but incorporated the FailSafe concept. If the incoming pulse train was corrupted, the decoder was shut down and a neutralising DC level was sent to the wiper pads in the servos. The throttle was set to low and controls to neutral. coders had the dreaded "Fail-Safe" built into the system. In retrospect, the "Streakers Defence" applied in this case. It did seem like a good idea at the time and I can remember being very impressed with the concept. In those days many of us were still flying what were virtually free-flight models with a very high degree of natural stability built in. If the radio failed, and they did fail more often in those early days, the model kept flying by itself. The motor was cut by the Fail-Safe and all one had to worry about was the odd thermal which carried off many a model, never to be seen again. Keep in mind also that our old friend "V2 " is a component of kinetic energy and cutting the throttle is very important as it reduces crash damage considerably. It still does and I am all in favour of Fail-Safe throttle even now. My real objection to Fail-Safe is in the locking out of the controls once Fail-Safe is activated. However, and here is the crux of the story, by 1964 modellers had discovered the neutrally stable aerobatic aircraft and now we have a vastly different story. Neutralised controls on this type of model are a death sentence, hence the epithet above. These things flew as straight as an arrow in the direction of the last control command and once control was locked out, crash they certainly did. It did not take long for the designers to wake up to the fact that some control was better than none, thus Fail-Safe was consigned to the rubbish bin and models were allowed to fly through interference or weak levels of RF until control was regained properly. The odd snatch of control available in the noisy periods was often enough to keep the model flying. The problem with Fail-Safe is that once the decoder decides that the signal is unreadable and shuts itself down, all control is lost until the decoder deems it proper to restore it. I personally dislike having electronics decide. for me when I can or cannot have control of my model. Fail-safe is an invalid concept in theory, proved itself invalid in practice and was quite correctly consigned to the rubbish bin; that is, until the new generation of university trained designers were turned loose into the practical world and dragged it out again in the form of the PCM set. Even these people learned quickly, The first really successful commercial proportional system appeared around 1964 in the shape of the Bonner Digimite and featured, for those days, absolutely revolutionary ideas. They were heady days for modellers and I can still remember the excitement generated by the American advertising. Bonner was a leading manufacturer of servos for use in reed receivers and when he went to a proportional system he spared no expense to make it the best available and it was. It gave good service to many people for many years - quite an achievement for a pioneer set. It did, however, feature Fail-Safe which was a pity, but there was little known about this concept in those days. Bonner followed the Spreng and Mathers concept in which a serial stream of pulses are transmitted to the receiver and then passed to a serial to parallel converter for decoding. Fig.1 (repeated from last month) shows the timing sequence for this serial to parallel conversion. The system is termed Pulse Position Modulation (PPM) and in this system a master clock in the transmitter triggers a cascaded series of pulse generators. Each of these generates a pulse, the width of which is controlled by the potentiometer coupled to the transmitter control stick. Convention has this width at 1.Sms for neutral; lms for minimum and Zms for maximum pulse width. Depending upon the number of channels (controls), a set will have APRIL 1991 87 CH2,3,4,5 CH1 .005 CH6 1k 560k 27k I I cc 01 2 I cc o-:al"·-+-'WV.-----+-1. .005 .005 I .005 4.7k 10k I I 10k 10k I I OS I OS OS 1N914 1N914 1N914 I HAST STAGE ONLY I REPEAT FOR EACH CHANNEL Fig.2: this serial to parallel decoder is based on BRY39 silicon controlled switches, one for each servo channel. The circuit was simple yet reliable & was used for many years until IC decoders appeared on the scene. from two to eight pulse generators. These serial pulses are then converted into a marker pulse stream in which a 350µs marker pulse marks the beginning and end of each pulse. Transmission is continuous, with a new frame transmitted every 16-20ms (new clock pulse). Thus, in a 4-channel set with a frame rate of 16ms, full deflection on all controls will result in a data stream 4 x 2ms long followed by a resting period of 16 - 8ms or 8ms. This rest period is used as an identification or synchronisation pause. This serial data stream may be transmitted by NBFSK or amplitude modulation and the receiver passes on a duplicate of this data to the decoder. The decoder is essentially a serial to parallel converter and there is a wide varity of approaches 'to the decoding process. However, all follow the Spreng and Mathers concept of reconstituting the serial stream to the original number of variable width pulses which are essential for the operation of the proportional servo (described last month). Bonner used an 8-transistor array in a Johnson ring counter, with a diode matrix for decoding. Frame validity was verified by a separate counter. Bonner went the whole hog and came out with an 8-channel set and decoding alone took 15 transistors. If the incoming pulse train was corrupted, the decoder was shut down and a neutralising DC level was sent to the wiper pads in the servos. The throttle was set to low and the controls to neutral. As you can imagine, this was quite an elaborate circuit for discrete corn- A_ _ _ _ _ _ _ _ _ _ _ _ _.___ _ _ _~_ _..._ _ _ _ _ _.___ _ +4.8V 14 B 12 68k .,. IC2 74C164 6 10 11 12 13 .,. Fig.3: this circuit used a 74C164 serial to parallel decoder & is still current today. However, many manufacturers are now going over to custom ICs which enable them to incorporate more features. 88 SILICON CHIP ponents and the set was a little bulky. The problem with this system was that corrupt data was often encountered and the set immediately went into lock-out until valid data was again established, thus denying the pilot access to the controls. Quite often this corrupt data was only present just long enough to activate the Fail-Safe. Once activated, the pilot had to wait out the time-out period, thus the FailSafe exaggerated what was in reality a very minor glitch - one that the pilot may not have noticed under normal conditions. He certainly noticed the throttle come off and the controls fly back to neutral and stay there, even if it was only for a very brief time. But at 100km/h, even a very brief time can be disastrous. The lessons learned from this system and many others were quickly picked up , and the second generation systems came out without Fail-Safe , the concept being that it was better to let the model fly through the corrupt data. The era of truly reliable radio control modelling had begun. Bonner never learned the lesson and stuck with Fail-Safe and gradually faded from the market. Decoder development followed quickly from there on and there were many ingenious circuits, all aimed at improving reliability and reducing component count. This in turn gave smaller size and lighter weight. One very popular circuit was that shown in Fig.2. The heart of this was the SCS (silicon controlled switch). One switch was used per channel and the pulses just simply stepped through the counter. The output was a positive pulse whose width equalled the distance between the leading edges of the clock train. Simple and reliable , this circuit was used until the IC decoder began to appear. The IC decoder had a patchy beginning and was usually cobbled together out of a number of chips. JK flipflops were a popular item and in 2-channel sets the 4013 dual-D flipflop is still used extensively. The problem with using several IC chips is that they are expensive in regards to board space and size is always a problem in R/C receivers. This was particularly true in the days before surface mount devices. Three 14-pin DIP packs would use all of the space available and thus IC decoders were seen to appear in one manufacturer's equipment while others stuck with the SCS or discrete decoders. The most usual reason in those days for going to ICs was just simply to hop on the bandwagon. Then the serial to parallel decoder made its very welcome appearance. Here was a single chip solution and chips such as the 74C164 would give 8 simultaneous controls in a single chip. Fig.3 is a circuit of a decoder using this chip. It is part of the circuit featured on page 111 of the December 1990 issue. The 74C04 is used as an This modern radio-control transmitter uses pulse code modulation (PCM) techniques to provide simultaneous 7channel control. Other features include channel mixing, dual rate control, trim adjustment & servo end point adjustment. audio amplifier/shaper/inverter. Briefly the circuit in Fig.3 works as follows . Transistor Q5 is used as a small signal amplifier with a slicing action. Thus, low level noise is eliminated and the amplified pulse train is passed on to the 74C04. This acts as Mailbag - continued from page 5 "Much more expensive to repair": how do you look at the modulation on an FM Tx? Answer: with great difficulty or use a modulation meter. Quoting my own case, having manufactured AM sets for many years, suddenly my test equipment was inadequate. There followed a spending spree on new test equipment which included a modulation meter, a more elaborate signal generator and a more accurate frequency counter, amongst other things. Then followed a stock of more expensive crystals and other components, and believe me broken crystals are a big item in R/C receivers. Add to this a more elaborate alignment procedure. Need I go on? "Much more expensive and sometimes more difficult to change crystals in": this is a very important practical consideration. Quoting from the Futaba (Aust.) price list again: AM crystals, $24.95 per pair; FM crystals, $38.50 per pair. Because of the narrow bandwidth of some FM sets, crystal tolerances can put the frequency outside the passband with a loss of range occuring. Moral - always check the range after crystal changes. Complexity covers more than component count and includes alignment which we have already covered. The "simple AM receiver" was included as a bit of history to illustrate the development of narrow band spacing without elaborate ceramic filters. I did point out that it was a 20-year old design. A modern AM receiver using ICs in the RF section (as do the FM examples you gave) would present a much lower component count. The question is would they work any better and the answer is probably not. Capture effect was the weakest statement in the article and probably should not have been included. But an inverting and squaring amplifier to provide the necessary pulse information to the 74C164. The output of pin 2 is the clock stream and is applied to pin 8 of the 74C164 . Pin 4 of the 74C04, D3 and the .033µF capacitor comprise the identification network or sync separator. Pin 6 of the 74C04, D4 and the 2.ZµF capacitor comprise the chip enable network. This network filters the incoming pulse train and sends the chip enable (pin 9) high. Thus, the chip is disabled if there is no incoming pulse train. This prevents random noise from damaging the servos by driving them hard up against the end stops. The timing still follows the broad outlines of Fig.1. This type of decoder is still viable today for PPM, however the larger manufacturers have begun to move over to custom ICs which incorporate several features not found in off-theshelf decoding ICs. Such features as voltage regulation and noise filtering are often built into the decoder chip, thus reducing even further the component count. The really significant development in decoding, however, has been in the area of the microprocessor and here there is great promise for the future. SC as you point out, it is laboratory demonstrable and I do seem to remember a series of editorials in RCM&E some years ago on "Pirated models due to capture effect". Actually, I thought I was being very fair in the article as I gave pros and cons for both systems. The remarks on oscillator design were virtually a direct quote from my friend who checked the article. I had forgotten to mention the supply rail stabilisation and he pointed this out to me. All of these remarks I heartily endorse. I did not say design was impossible but that NBFSK placed "more stringent demands on the designer". I stand by these remarks. All of the NBFSK oscillators I examined had zener stabilised supply rails and heavy decoupling. I have yet to see an AM transmitter with a zener stabilised oscillator. Bob Young, Silvertone Electronics, Riverwood , NSW. APRIL 1991 89 Silicon Chip BACK COPIES May 1988: Optical Tachometer For Aeromodellers; High Energy Ignition For Cars; Ultrasonic Car Burglar Alarm; Walkaround Throttle For Model Railroads, Pt.2; Designing & Building RF Attenuators; Motorola MC3334P High Energy Ignition IC Data. July 1988: Stereo Control Preamplifier, Pt.2; Fitting A Fuel Cut-Off Solenoid; Booster For TV & FM Signals; The Discolight Light Show, Pt.1; Tone Burst Source For Amplifier Headroom Testing; What Is Negative Feedback, Pt.3; Amcron MA-1200 Power Amplifier Review; Amplifier Headroom - Is It A Con? August 1988: Building A Plasma Display; Universal Power Supply Board; Remote Chime/ Doorbell; High Performance AC Millivoltmeter, Pt.1; Discolight Light Show, Pt.2; Getting The Most Out Of Nicad Batteries; Data On Insulated Tab Triacs. September 1988: Hands-Free Speakerphone; Electronic Fish Bite Detector; High Performance AC Millivoltmeter, Pt.2; Vader Voice; Motorola MC34018 Speakerphone IC Data; National Semiconductor LM12 150W Op Amp Data & Appl ications; What Is Negative Feedback, Pt.4. October 1988: Stereo FM Transmitter (Uses Rohm BA1404); High Performance FM Antenna; Matchbox Crystal Set; 'Electronic House Number; Converting A CB Radio To The 28MHz Band; Queensland's Powerful Electric Locomotives. Computer Sound Repeater; 120W PA Amplifier (With Balanced Inputs) Pt.1; How To Service Car Cassette Players; Massive Diesel Electrics In The USA; Marantz LD50 Loudspeakers . November 1988: 120W PA Amplifier Module (Uses Mosfets); Poor Man's Plasma Display; Automotive Night Safety Light; Adding A Headset To The Speakerphone; How To Quieten The Fan In Your Computer; Screws & Screwdrivers, What You Need To Know; Diesel Electric Locomotives. February 1989: Transistor Beta Tester; Minstrel 2-30 Loudspeaker System; LED Flasher For Model Railways (uses LM3909); Build A Simple VHF FM Monitor (uses MC3362), Pt.1; Lightning & Electronic Appliances; Using Comparators to Detect & Measure . December 1988: 120W PA Amplifier (With Balanced Inputs), Pt.1; Diesel Sound Generator; Car Antenna/Demister Adaptor; SSB Adaptor For Shortwave Receivers; Electronics & Holden's New V6 Engine; Why Diesel Electrics Killed Off Steam; Index to Volume 1. March 1989: LED Message Board, Pt.1; 32Band Graphic Equaliser, Pt.1; Stereo Compressor For CD Players; Map Reader For Trip Calculations; Amateur VHF FM Monitor, Pt.2; Signetics NE572 Compandor IC Data; Electronics For Everyone - Resistors. January 1989: Line Filter For Computers; Ultrasonic Proximity Detector For Cars; Simple April 1989: Auxiliary Brake Light Flasher; Electronics For Everyone: What You Need to Know l -__ _ ---------------------------------- Use this handy form to order your back copies Please send me a back O September 1988 0 0 February 1989 0 o July 1989 0 0 December 1989 O O May 1990 O O October 1990 O O March 1991 issue for: October 1988 March 1989 August 1989 January 1990 June 1990 November 1990 0 O 0 0 0 0 0 May 1988 November 1988 April 1989 September 1989 February 1990 July 1990 December 1990 0 July 1988 December 1988 0 May 1989 O October 1989 o March 1990 o August 1990 o January 1991 o Enclosed is my cheque/money order for $______ or please debit my: Card No. L____L___L___L___JI IL__~ L__I L__I~L__I ~ I ~~ Signature _ _ _ _ _ _ _ _ _ _ _ _ Card expiry date_ _ /_ _ Name _______________________ _ __ I I I I Street - - - - - - - - - - - - - - - - - - - - - Suburb/town __ _ _ _ _ _ _ _ _ _ _ _ Postcode______ O Bankcard 0 0 O 0 0 0 0 August 1988 January 1989 June 1989 November 1989 April 1990 September 1990 February 1991 0 Visa Card O Master Card $5.00 each (includes p&p). Overseas orders add $1 each for postage.. NZ orders are sent air mail. Detach and mail to: SILICON CHIP PUBLICATIONS PO BOX 139 COLLAROY BEACH NSW 2097 Or call (02) 979 5644 & quote your credit card details. Fax (02) 979 6503 1 I I--------------------- -- - - -- - ----------~'90 SILICON CHIP Cost Dual Power Supply; Inside A Coal Burning Power Station ; What To Do When Your Computer Goes Bung, Pt.3 ; Digital Waveform Generation Using A Computer, Pt.4. August 1990: High Stability UHF Remote Transmitter; Universal Safety Timer For Mains Appliances (9 Minutes) ; Horace The Electronic Cricket; Digital Sine/Square Wave Generator, Pt.2 ; The Tube Vs. The Microchip (Two Shortwave Receivers Compared) ; What To Do When Your Computer Goes Bung , Pt.4. September 1990: Music On Hold For Your Telephone; Remote Control Extender For VCRs ; Power Supply For Burglar Alarms; LowCost 3-Digit Counter Module ; Voice Mail For Your Computer; Simple Shortwave Converter For The 2-Metre Band ; How To Make Dynamark Labels. About Capacitors ; Telephone Bell Monitor/ Transmitter; 32-Band Graphic Equaliser, Pt.2 ; LED Message Board, Pt.2 . May 1989: Electronic Pools/Lotto Selector; Synthesised Tom-Tom ; Biofeedback Monitor For Your PC ; Simple Stub Filter For Suppressing TV Interference ; LED Message Board, Pt.3; Electronics for Everyone - All About Electrolytic Capacitors. June 1989: Touch-Lamp Dimmer (uses Siemens $LB0586); Passive Loop Antenna For AM Radios ; Universal Temperature Controller; Understanding CRO Probes; LED Message Board, Pt.3; Coherent CW - A New Low Power Transmission Technique . July 1989: Exhaust Gas Monitor (Uses TGS812 Gas Sensor) ; Extension For The Touch-Lamp Dimmer; Experimental Mains Hum Sniffers ; Compact Ultrasonic Car Alarm ; NSW 86 Class Electric Locomotives ; Facts On The PhaxSwitch - Sharing Your Phone Line With A Fax Machine. August 1989: Build A Baby Tower AT Computer; Studio Series 20-Band Stereo Equaliser, Pt.1; Garbage Reminder· A 7-day Programmable Timer; Introduction To Stepper Motors; GaAsFet Preamplifier For The 2-Metre Band ; Modern 3-Phase Electric Locomotives. September 1989: 2-Chip Portable AM Stereo Radio (Uses MC13024 and TX7376P) Pt.1 ; Alarm-Triggered Telephone Dialler; High Or Low Fluid Level Detector (uses LM1830N); Simple DTMF Encoder (uses Texas TMC5089); Studio Series 20-Band Stereo Equaliser, Pt.2 ; Auto-Zero Module for Audio Amplifiers (Uses LMC669); A Guide To Hard Disc Drives. October 1989: Introducing Remote Control; FM Radio Intercom For Motorbikes (Uses BA1_404 And TDA7000) Pt.1; GaAsFet Preamplifier For Amateur TV ; 1Mb Printer Buffer; 2- , Chip Portable AM Stereo Radio, Pt.2 ; Installing A Hard Disc In The PC ; A Look At Australian Monorails. November 1989: Radfax Decoder For Your PC (Displays Fax, RTTY and Morse); Super Sensitive FM Bug ; Build A Low Cost Analog Multimeter; FM Radio Intercom For Motorbikes, Pt.2 ; 2-Chip Portable AM Stereo Radio, Pt.3; Floppy Disc Drive Formats & Options; The Pilbara Iron Ore Railways. December 1989: Digital Voice Board (Records Up To Four Separate Messages, Uses Texas TMS3477NL and 256K RAMs) ; UHF Remote Switch ; Balanced Input & Output Stages ; National Semiconductor LM831 Low Voltage Amplifier IC Data; Install A Clock Card In Your PC ; Index to Volume 2 (JanuaryDecember 1989). January 1990: Service Tips For Your VCR; Speeding Up Your PC ; Phone Patch For Radio Amateurs; High Quality Sine/Square Oscillator; Active Antenna Kit; The Latest On High Definition TV; Speed Controller For Ceiling Fans; Designing UHF Transmitter Stages. February 1990: 16-Channel Mixing Desk; High Quality Audio Oscillator, Pt.2 ; The Incredible Hot Canaries; Random Wire Antenna Tuner For 6 Metres; Phone Patch For Radio Amateurs, Pt.2; PC Program Calculates Great Circle Bearings. October 1990: Low-Cost Siren For Burglar Alarms; Dimming Controls For The Discolight; Surfsound Simulator; DC Offset For DMMs; The Dangers of Polychlorinated Biphenyls; The Bose Lifestyle Music System ; Using The NE602 In Home-Brew Converter Circuits. November 1990: Low-Cost Model Train Controller; Battery Powered Laser Pointer; A Really Snazzy Egg Timer ; 1.5V To 9V DC Converter; How To Connect Two TV Sets To One VCR ; Introduction To Digital Electronics; Simple 6-Metre Amateur Transmitter. December 1990 : DC-DC Converter For Car Amplifiers ; The Big Escape ; Wiper Pulser For Rear Windows; Versatile 4-Digit Combination Lock; 5W Power Amplifier For The 6-Metre Amateur Transmitter; The Green CD Pen Controversy. March 1990: 6/12V Charger For Sealed LeadAcid Batteries ; Delay Unit For Automatic Antennas; Workout Timer For Aerobics Classes ; 16-Channel Mi xing Desk, Pt.2 ; Using The UC3906 SLA Battery Charger IC; Digital Waveform Generation Using a PC ; The Controls On A Model Aircraft. January 1991: Fast Charger For Nicad Batteries, Pt.1; Have Fun With The Fruit Machine ; Two-Tone Alarm Module ; Laser Power Supply (For Tubes With Ratings Up To 10mW) ; LCD Readout For The Capacitance Meter; How Quartz Crystals Work; The Dangers When Servicing Microwave Ovens; Electric Vehicles - The State Of The Art. April 1990: Dual Tracking ±50V Power Supply; VOX With Delayed Audio ; Relative Field Strength Meter; 16-Channel Mixing Desk, Pt.3 ; Simple Service Tips For Your Microwave Oven; Maciel Aircraft Aerodynamics ; Active CW Filter For Weak Signal Reception. February 1991 : Synthesised Stereo AM Tuner, Pt. 1; Three Inverters For Fluorescent Lights ; Low-Cost Sinewave Oscillator; Fast Charger For Nicad Batteries, Pt.2 ; How To Design Amplifier Output Stages; Tasmania's Hydroelectric Power System . May 1990: Build A 4-Digit Capacitance Meter ; High Energy Ignition For Cars With Reluctor Distributors ; The Mazzie CW Transceiver; Waveform Generation Using A PC, Pt.3 ; 16Channel Mixing Desk, Pt.4; What To Do When Your Computer Goes Bung , Pt. 1; Electronic Load For Checking Power Supplies. March 1991 : Remote Controller For Garage Doors, Pt.1; Transistor Beta Tester Mk.2; Synthesised AM Stereo Tuner, Pt.2; Multi-Purpose 1/0 Board For PC-Compatibles; Universal Wideband RF Preamplifier For Amateurs & TV ; A Look At Config.Sys & Ansi.Sys ; High-Voltage DC Transmission Systems. June 1990: Multi-Sector Home Burglar Alarm ; Low-Noise Universal Stereo Preamplifier; Load Protection Switch For Power Supplies; A Speed Alarm For Your Car; Design Factors For Model Aircraft; Fitting A Fax Card To Your Computer; What To Do When Your Computer Goes Bung, Pt.2. July 1990: Digital Sine/Square Generator, Pt.1 (Covers 0-500kHz); Burglar Alarm Keypad & Combination Lock; Simple Electronic Die; Low- PLEASE NOTE: All issues from November 1987 to April 1988, plus June 1988, are now sold out. All subsequent issues are presently in stock. For readers wanting articles from issues out of print, we can supply photostat copies (or tearsheets) at $5.00 per article, including postage. When supplying photostat articles or back copies, we automatically supply any relevant Notes & Errata , at no extra charge. APRIL 1991 91 ASK SILICON CHIP Got a technical problem? Can't understand a piece of jargon or some technical principle? Drop us a line and we'll answer your question. Write to: Ask Silicon Chip, PO Box 139, Collaroy Beach, NSW 2097. High energy ignition works well I have recently bought and assembled successfully a High Energy Ignition Kit from Jaycar Electronics, as described in the May 1988 issue of SILICON CHIP. I am pleased to say that it works very well and have had no trouble with it since installing it into my 1979 929L Mazda. In your June 1988 issue, you described a method of converting a car's distributor to Hall Effect using either the Sparkrite kit or the Bosch Vane/Siemens sensor combination. I would very much like to convert my car to Breakerless Ignition using the Sparkrite kit, as no metalwork or extensive fiddling is required. I have only one problem and that is I cannot find anyone who sells this kit in Brisbane. Jaycar no longer stock this kit and no auto electrical stores I have been to have heard of it. I would really appreciate it if you or any of your readers could supply me with some information on a place in Brisbane or Australia that still stocks this kit. (T. G., Seven Hills, Qld). • As far as we know, the Sparkrite breakerless conversion kit is no longer manufactured. You are quite right Unwanted amplifier switch-off thump Your "Ask SILICON CHIP" column has induced me to write to you about a continual problem that I have had over the years. I am prepared to offer a $50.00 fee for a simple, uncomplicated to build, system to cure the problem below. I have tried the power supply kit described in the December 1979 issue of ETI in order to stop the noise when an amplifier switches on and off. The ETI kit works very well at switch on, but not all the 92 SILICON CHIP though, it is an ideal method of conversion. You could consider obtaining a distributor from a later model from a wrecker's yard, which would make the conversion a snack. Failing that , you will have to look around for a Hall Effect conversion kit for your car. We understand that the American companies Lumenition and Allison do make a wide range of Hall Effect conversion kits and a fair number of Japanese cars are covered. The best place to find out more about these would be your local speed shop - don't bother with ordinary auto accessory shops as they probably won't know what you are talking about. Alternatively, contact Lynx Engineering Pty Ltd in Croydon (phone (02) 747 2222) for info on Allison products. Leak amplifier has leaky capacitors I have a Leak amplifier 50+50 which I would like to put to use, but most if not all, the electros are shot. It would probably be advisable to change them all. As these are rated at 250 volts at least, my problem is a source of supply. Might it also be possible that Garry time at switch off. Basically, I would like a system that does not connect the speakers for a few seconds after power is switched on and also holds the 240V AC power going into the amplifiers for a few seconds after the speakers have been switched off. I hope that you can help me. (G. D., Nambucca Heads , NSW). • We presently have a muting circuit under development which should suit your purpose. We hope to publish it in the coming June or July issue. We won't charge $50 for it, either. Cratt could run a series of introductory articles on satellites from the amateur point of view. Dependent on the interest shown, it could be either elaborated on, or dropped. (H. F. , Cloverdale, WA). • High voltage electros are available from two sources that we know of in Australia. One of these is Farnell 's and the other is RS Components. The addresses are as listed below: (1) RS Components: 3 Walters Drive, Osborne Park, WA 6017 (PO Box 502, Subiaco, WA 6008). Telephone (09) 244 3666. (2) Farnell Electronic Components: 72 Ferndell Street, Chester Hill, NSW 2162. Telephone (02) 645 8888 . A series of articles on satellite reception is in preparation and will be published in a few months' time. Inductance meter is interesting I read with great interest Victor Erdstein's article on his inductance meter design (See "Circuit Notebook", page 20, February 1991). The design is exactly what I have been looking for. Will you be producing this at a later date as a kit? I was thrilled to see the AM tuner project, also in the February 1991 issue. Is there an FM tuner on the way? (B. C., Grange, SA) . • Thanks for your comment on the inductance meter. We do not have any plans to produce this as a kit at this stage but if sufficient readers express an interest, we will consider publishing it as a full project. We do not have plans for an FM tuner to match the AM tuner. Commercially available FM tuners are just too cheap to make an FM tuner project viable. Low tech blinkin' lights are cheaper I hope you will be able to help me with this problem. I've had these Christmas tree lights for a few years now and like them because they have a double blinker, or they did have two until one failed. Unfortunately, the blinker bulb is no longer available to replace the one that is not working. You may have seen these sets of blinking lights. One cycle is a fraction longer than the other and so makes it ever so nice to look at. It has 34 coloured lights, plus two of these special ones which cut and connect the circuit. Please let me know what you call these and how they work? Also, could you come up with some kind of relay or a circuit to replace this special bulb. (J. N., Mt.Warrigal, NSW). • The special bulbs which cause your Christmas lights to blink have an internal bimetallic strip which makes and breaks the electrical circuit. Your set of Christmas lights apparently has two separate series strings of 12VAC bulbs, with each series string controlled by its own flasher bulb. You can buy these bulbs from Tandy Electronics (Cat. 2 72-1097) but there is one problem. They are supplied with flying leads rather than the Edison screw base. You would have to remove the existing flasher bulb socket and wire the new bulb in its place, making sure that the connections are very well taped up for safety. Unfortunately, an electronic solution to replacing the flasher bulb is not simple. Firstly, two flasher circuits would be required, with separate wiring to each circuit. Secondly, the cost of all the parts for the flasher circuit, including a case, would far exceed the cost of buying a new lighting setup. Questions on digital circuitry I have a number of questions for you to answer. For a start, I was given a 4003 by a friend but neither of us know what it does or its pinouts. Could you supply these? I would also like to know the frequency limit of the 74HC series ICs. One last question: would you know where I can obtain a 6-8 digit counter IC with multiplexed outputs (of course) with as high a frequency rating as possible, as well as data on it? I will be using it to drive an 8-digit vacuum-fluorescent display, so I can't simply cascade a couple of 74C926s, or higher frequency versions of these. Help for sick a Jaguar I write to reply to J. E., Melbourne, regarding his problem with' Jaguar electronic ignition (see SILICON CHIP, February 1991, page 100 - "Sick Jag Needs Better Spark"). Without furth er information, I am not sure which system will be on his Jaguar but it is most likely to be the Lucas transistor assisted system using the Lucas BA12 coil. (Yes, they are around the $200.00 mark) . Firstly, a good mechanic with an ignition scope should be able to tell J.E. whether the trouble is, in fact , ignition or something else. Secondly, if the problem is ignition-related, then there are a number of options : (1) If the coil proves to be the I read in a recent issue of SILICON CHIP a reader's letter asking about a digital ohmmeter proj ect. Why not simply modify the Digital Capacitance Meter project (May 1990)? All that would be needed is a close tolerance capacitor and a switch to toggle between resistance and capacitance modes, as well as a close tolerance resistor for calibration. Now I would like to suggest a series of articles describing the design of high quality amplifiers , explaining all (or most) of the parameters involved in amplifier design and how to overcome certain problems and difficulties. I think that such a series would be greatly w elcomed by readers as decent amplifiers are not easy to design properly. (D. M., Christchurch, NZ). • We do not know what a 4003 IC is. All the data books we have of the 4000 series CMOS ICs do not list a 4003 . Nor do they list 4004 or 4005 devices. It appears that these are obsolete devices or were never rel eased for general us e. The frequency limit of a 74HC clocked IC is typically 50MHz and the propagation delay for a gate is 8ns. For more detailed information, w e suggest you obtain a High Speed CMOS data book. For a 6-8 digit counter, you can use a 74C912 6-digit display controller problem, and it is a Lucas BA12, then it can be substituted by a readily available, much cheaper coil. (I can supply details). (2) The whole system can be converted back to a points type distributor and the High Energy Ignition published in the May 1988 issue of SILICON CHIP used. (3) Depending on which Jag distributor it is, it should be possible to run the HEI from the reluctor pickup. (4) Again depending on the distributor, an aftermarket, optoelectronic or Hall Effect pickup can be substituted and also run into the HEI. If J.E. wishes to write or phone, I would be only too happy to help further. (I. L., PO Box 557 , Bowral, NSW 2576. Phone (048) 71 3162 (AH). plus separate 4-digit counters using the 74HC. Your idea to convert the Capacitance Meter from May 1990 into a digital ohmmeter is a good one - we'll have a look at publishing the modifications soon. Our February 1991 issue features the first part of a two-part article on amplifier design , which you should find interesting. The second part is published in this issue. Model aircraft projects wanted Thanks for a well presented magazine. My interest in electronics and model aircraft have been well catered for recently by your informative articles on remote control by Bob Young and projects for rapid chargers for nicad batteries (I use it for electric flight). A further project to complement these would be an electronic speed controller, suitable for model aircraft/ cars. Desirable features would include: a variety of current capacities (eg, 20 & 30 amps); the ability to operate from 4.8V receiver battery packs, with suitable isolation such as optoisolators ; and compact, lightweight construction. (M. R., Ringwood, Vic). • Thanks for your suggestions - we'll give them close consideration. SC APRIL 1991 93 -WORDERFORM / USE THIS FORM FOR ALL YOUR ALL SILICON CHIP PURCHASES SILICON CHIP BINDERS: Yes! Please rush me_ _ _ SILICON CHIP binder(s)<at> $A14.95 each including postage. (Overseas orders please addA$3.00 each for postage). Total $A._ _ _ __ SPORTS SHIRT: Please send me _ _ _ Sport Shirt(s)<at> $A24.95 including postage. (Overseas orders please add $A3.00 for the additional postage). Size(s): S(Qty)_ M(Qty)_ L(Qty)_ XL(Qty)_ XXL(Qty)_ . Total $A_ __ SLOPPY JOE: Please send me _ _ Sloppy Joe(s)<at> $A27.95 including postage. (Overseas orders please add A$3.00 for the additional postage). Size(s): S(Qty)_ M(Qty)_ L(Qty)_ XL(Qty)_ XXL(Qty)_ . Total A$_ __ BACK ISSUES: $A5.00 each (including postage). Overseas orders add $Al.GO per issue for postage. YEAR YEAR ISSUE ISSUE ISSUE YEAR ISSUE YEAR TOTAL $A SUBSCRIPTIONS .. RATES: □ NEW SUBSCRIPTION: Month to Start (PLEASE TICK ONE) 2 years (24 issues) 1 year (12 issues) O$A84 O$A42 Start In □ RENE WAL:SubNo. □ GIFT SUBSCRIPTION: Month To Start Your Details Australia Australia with Binder(s) O$A105 O$A53 Mr/Mrs/M s: NZ & PNG (Airmail) O$A130 O$A65 Overseas Surface Mail O$A130 O$A62 Overs.eas Airmail O$A240 O$A120 Address Postcode Daytime telephone number: _ _ _ _ _ _ __ Enclosed is my cheque/money order for $_ _ _ Gift Subscription Details Message: _ _ _ __ _ __ _ __ _ _ __ Mr/Mrs/Ms: _ _ __ _ _ _ __ _ _ _ __ Card expiry date Signature _ _ __ _ _ _ __ FAX f~7\ (02) 979 6503 Fax the coupon with your Credit Card details 24 Hours, 7 Days a Week Address: _ _ __ _ _ _ __ __ _ __ _ _ _!_ _ ,Er (02) 979 5644 _ _ _ __ _ __ _ _ _.Postcode_ _ __ 9am - 5pm Mon-Fri. Please have your Credit Card details ready. Mail coupon to: FREEPOST 25 Silicon Chip Publications PO Box 139 Collaroy Beach NSW 2097 No stamp required in Australia MARKET CENTRE Cash in your surplus gear. Advertise it here in Silicon Chip. FOR SALE WEATHER FAX programs for IBM XT/ ATs *** "RADFAX2" is a high resolution, shortwave weather fax, Morse & RTTY receiving program. Needs CGA, SSB l::IF radio & Radfax decoder. Also "RF2HERC", "RF2EGA" & "RF2VGA", same as RADFAX2 but suitable for Hercules, EGA & VGA cards respectively. $35. *** "SATFAX" is a NOAA, Meteor & GMS weather satellite picture receiving program. Uses EGA & r-------------------------, VGA modes, needs EGA or VGA col our monitor & card, plus "WEATHER FAX" PC card. $45. *** All programs are on 5.25-inch or 3.5-inch discs (state which) & include documentation. Add $3 postage. ONLY from M. Delahunty, 42 Villiers St, New Farm, 4005 Old. Phone (07) 358 2785. LAB LASERS. 0.5mW to 2mW HeNe lasers complete. Ideal for students or hobbyists. Australian made. $440 to $640. Phone M.C.E. Lasers (03) 357 0055. CLASSIFIED ADVERTISING RATES Advertising rates for this page: Classified ads - $7.00 for up to 15 words plus 40 cents for each additional word. Display ads (casual rate) - $20 per column ,centimetre (Max. 10cm). Closing date: five weeks prior to month of sale. If you use a PO Box number, you must include your permanent address and phone number for our files. We cannot accept ads submitted without this information. To run your classified ad, print clearly on the lines below or on a separate sheet of paper & send the form together with your cheque or credit card details to : Silicon Chip Classifieds, PO Box 139, Collaroy Beach, NSW 2097. Or fax the details to (02) 979 6503. THE WORLD'S FIRST MS-DOS pocket PC at Australia's lowest price. Atari Portfolio $480 inc tax. Post & insurance free for mail orders. All accessories available at reduced prices. Uses an 80C88 CPU & is video cassette size. Data transfer to XT/AT via optional serial or parallel interface. For more information, send a 43c stamp to: Don McKenzie, 29 Ellesmere Crescent, Tullamarine 3043. DIGITAL WAVEFORMS from a PC. As described in SILICON CHIP in March 1990, May 1990 & June 1990. The software can also be used for the similar project (Simple PC Function Generator) described in Electronics Australia in January 1989. Software & PC Board: $39.95 incl. p&p. Software only: $32.50 incl. p&p. Money order or IIT MATHS COPROCESSORS Enclosed is my cheque/money order for $_ _ _ _ or please debit my D Bankcard D Visa Card D Master Card X I I I Signature_ _ _ _ _ _ _ _ _ _ _ Card expiry date_ _~ - - - I I Name _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ I I Street _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ I I Suburb/town _ _ _ _ _ _ _ _ _ _ _ _ Postcode_ _ _ _ __ L _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ JI Card No. 2C-08 2C-10 2C-12 2C-20 2C87- 8MHZ 2C87-10MHZ 2C87-12MHZ 2C87-20MHZ /:" °'1&1: ~~ ,r:-0 '.-9 ( $330 $359 $430 $490 ~&& 3C-16 3.C87-16MHZ $640 3C-20 3C87-20MHZ $680 3C-25 3C87-25MHZ $840 3C-33 3C87-33MHZ $990 These pices include Sales Tax. Stocks are limited at this price, so order early. CAD CONNECTION PHONE (02)957 6719 CONNECTION FAX (02)954 5550 Improving Your Produdirity APRIL 1991 95 r MEMORY EXPANSION SIMM&SIP sons CO-PROCESSORS 21.00 73.00 375.00 68.00 9 x256 9x1MB 9x4MB 8x1MB DRAM/DIP 58.00 2.10 2.50 2.15 7.60 7.60 PELHAM 80287-10 TOSHIBA LAPTOP INTEL 175.00 285.00 295.00 582.00 510.00 640.00 13200 T1600 T3100E T3100SX T1000SE A. M. D. SAVE 50% ON CO-PROCESSORS BOns 4MB Static 41256 41464 4164 1MB .414256 INTEL8087·1 INTEL 287XL ITT 3C87SX16 ITT 3C87 -33 CYRIX 387DX20 CYRIX 387DX25 Price• At February 24th 168.00 3MB 2MB 2MB 2MB 2MB 4:10.00 270.00 270.00 270.00 480.00 185.00 200.00 200.00 Sales Tax 20%. Overnight Delivery. Credit Cards Welcome 1st Floor, 100 Yarrara Road, Pennant Hills, N.S.W. 2120 Tel(02)980-6988 Arista .. ..... ...... ...... ... ... .... . 33,39,57 Cad Connection .... .................. .. 95 David Reid Electronics ........ IFC ,1 IBM PS/2 1MB 2MB 2MB Altronics ...... .............. ..... ... .. .. 60-63 Back Issues .. .. ...... ..... ... ... .. ... 90,91 COMPAQ 386-20, 386-25, 386-20E, 386-S, 386-33 4MB MODULES 490.00 4MB BOArds 580.00 30/286,50 70E61,1212 70A21 Advertising Index Fax(02)980-6991 \.. Dick Smith Electronics ... ....... 13-15 Electronic Solutions ..... .... ......... 35 Electronic Toy Services ............ 96 Electronics World ...................... 75 Elmeasco ....... .. .... ........ ... ... ..... IBC Geoff Wood Electronics ... ........ . 29 Harbuch Electronics ...... .. ........ 57 MODEL TRAIN CONTROLLER project, SILICON CHIP, November 1990, $19.95 plus $2.50 p&p. Plugpack, 12VAC, 1.7A, suitable for the above (use rectifier), $29.95 plus $4.00 p&p. Kits built & repaired. Prototype production board supplier to the hobbyist & supplier of SILICON CHIP project PCBs. ETS, PO BOX 491, NOARLUNGA CENTRE, SA 5168. Phone: (08) 382 8919 MAX 1/0 Board Kit $149.00 Built & Tested $269.00 • 7 x Relays SPST 2 amps each • 8 x Switch inputs (TTL) • 1 x DAG (Digital to Analog converter) • 1 x ADC ( Analog to Digital converter) • 4 x Motor Drive outputs (40mA ea.) • 1 x Programmable timer output. MAX includes a 20-page manual with all schematics, parts layout etc. , a 360K PC-compatible floppy with diagnostic and sample software in GW-Basic. MAX runs from a PC compatible printer port tor full compatibility with a large range of computers. Same day dispatch of orders . Credit cards or personal cheques welcome. Phone (08) 332 6513 or Fax (08) 364 0902 (24 hours) PC Computers, 36 Regent St, Kensington, SA cheque . M. Radvanyi, PO Box 49, Kingswood, NSW 2749. CIRCUIT DESIGN SOFTWARE. Design your own .008% THD Sinewave Generator from 90Hz-30kHz using the PCB in SILICON CHIP, February 1991. No PCB track mods required. $20 inc. p&p. Design & build you own Audio Power Amplifier up to 20W. On-screen circuit diagram and hardcopy facilities. Instructions included. $30 inc. p&p. Custom-make your own SLA Battery Charger using the UC3906 IC (4-30V). Designed by the author of the SILICON 96 SILICON CHIP FIX-A-KIT $20.00 PER HOUR LABOUR 3 MONTHS WARRANTY ON REPAIRS 12 MONTHS WARRANTY ON CONSTRUCTION Service to most types of electronic equipment TECHNICAL ASSISTANCE HVCAL ELECTRONICS Design, Manufacture & Repair of Electronic Equipment Trading Hours Sam to 3pm, Monday to Friday (02) 633 5897 Hycal Instruments .................... 96 Jaycar Electronics ................ 45-52 J.V. Tuners ........... ..... ................ 43 M. Radvanyi ...... ...... .. ... .... ......... 95 PC Computers .... .. ... ... .. ............ 96 PC Marketplace ......... ... ..... .. ..... 77 Pelham .................. ..... ..... ........ 96 Raytec Data Systems .. ............ 43 CHIP March 1990 project. $20 each inc. p&p. Buy all three for $50 and save $20! All software IBM/XT/AT compatible, 5.25inch 360K disc only, CGA/EGA/VGA, MS-DOS 3.2 or later, GWBASIC required . 14-day turnaround . Send cheque/money order to: D. Yates, PO Box 134, French's Forest, NSW 2086 . ANTIQUE RADIO ANTIQUE RADIO restorations. Your one-stop electronic repair shop. Specialising in restoring vintage radios including chassis rewiring, quality new parts, valves , valve sockets, speakers, transformers, cabinet restoration. Quality secondhand radio dials & parts for most brands & models. About 400 radios in stock for restoration & parts. Every restored wireless is covered by a 2-year warranty on parts & service. French polishing of timber cabinets available. Vintage car radios in valve & transistor types available for restoration. Repairs done on tape decks, amplifiers, TVs & videos . Open Sat. 10am-5pm; Sun. 12.30-5pm. 109 Cann St, Bass Hill, NSW 2197. Phone (02) 645 3173 BH or (02) 726 1613 AH . RCS Radio................................ 44 Resurrection Radio ... .. .. .. .. ... .... 39 Rod Irving Electronics .... .... .. 20,21 68,69,84,85 Sheridan Electronics ................ 83 Silicon Chip Binders .... ... ... .. OBC Soundring ......... .. .. ........ .. .. ... ... . 33 Subscriptions ... .. .... ................... 94 PC Boards Printed circuit boards for SILICON CHIP projects are made by: • Electronic Toy Services, 2/111 Glynville Drive, Hackham West, SA 5163. Phone(08)3828919. • Jemal Products, 5 Forge St, Welshpool, WA 6106. Phone (09) 350 5555. • Marday Services, PO Box 19-189, Avondale, Auckland, NZ. Phone 88 5730. • RCS Radio Pty Ltd, 651 Forest Rd, Bexley, NSW 2207. Phone (02) 587 3491. Data I/ 0 2900 Programming System the new standard in affordable device DATA I/O programming Corporation F eatures • Universal pin driver technology eliminates pinout adaptors and gives long term flexibility in device support. • Standard 40 pin DIP socket • Optional Matchbooks\™ provide quick, easy handling of LCC and PLCC surface mount devices. from $7586 (ex tax) • • • • • • 128kByte standard RAM is expandable to 2MB to accommodate future devices. Flexible interfacing allows 2900 to easily fit any engineering environment. Control from existing terminals or from a PC. High speed 1/0 offers fast uploading and downloading of large data files - up to l 15kbaud between the 2900 and a PC. Up to ten times faster than conventional RS232. For RS232 communications, SmartPort1 M automatically senses protocol of the host and sets up the 2900 to match. No cables to rewire, no switches to set. Job files and macros make setups automatic for frequently used routines Autobaud™ automatically senses the baud rate of the host and sets up the 2900 accordingly. • Device Libraries Device Type Memory Floppy disks provide fast and easy device-support updates and local storage of frequently used files. Memory Librarv E/EEPROM 28 (standard on all 2900 systems) E/EEPROM All Memory PROM All Microcontrollers Logic Logic Logic E-micros All PLO 24 PLO 28 PLO 44 Devices Included All EPROMs and EEPROMs up to 28pins All EPROMs and EEPROMs All bipolar and CMOS PROMs All microcontrollers with on-board EPROMs All PLDs up to 24 pin All PLDs up to 28 pin All PLDs up to 44 pin ELMEASCO Instruments Ply.Ltd. Australia 's Leading Test & Measuring Instrument Company NEW SOUTH WALES 18 Hilly Street, MORTLAKE P.O.Box 30, CONCORD NSW 2137 Tel : (02) 736 2888 Telex : AA25887 Fax : (02) 736 3005 VICTORIA 12 Maroondah Highway, RINGWOOD P.O.Box 623 , RINGWOOD VIC 3134 Tel : (03) 879 2322 Telex : AA30418 Fax: (03) 879 4310 QUEENSLAND 192 Evans Road , SALISBURY P.O.Box 274 SALISBURY OLD 4107 Tel : (07) 875 1444 Fax: (07) 277 3753 SOUTH AUSTRALIA 241 Churchill Road, PROSPECT P.O.Box 154 PROSPECT SA 5082 Tel : (08) 344 9000 Telex: AA87519 Fax: (08) 269 6411 W. AUSTRALIA 32 Teddington Road, VICTORIA PARK, W.A. 6100 Tel: (09) 470 1855 Fax: (09) 470 3173