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New column on computer hardware ~ =9!!!~~~~~ -~~3~~ ,... - - - -- - --- --- -- -- --- -~ ~ _.- _, _, _, ___, a _, _, .-J SERVICING - - HIFI - E\ _ E.t1l\O"'~~t,5(ilj;i;tj•l[• s () # '.c . . - .. .__ .•- ~: ~ ~ -· •.w;_. I ~~------- ; A . •· l !' ~ r ""\.: .,- ~ ~~.. , ., - ·r-'"lll ,..____,,,, 1/ / , "'. ,· . -~ .✓ ·. ~. ',' • . . J iliiM!ElilU TheProfessional'sComputer: --.... .....-- - -- - -...... ......- It's a fact: over 90% of sales of l~~ Computers have been to executives who demand a reliable, quality product at an affordable price... with a genuine guarantee and warranty. IPC Computers give you that - and so much more. RELIABILITY: Absolute reliability: every IPC computer What a choice! With IPC YOU choose the model and options you requ ire -- fro m XT, AT, NEAT and 386 compatibles , with over l 50 options avail able - incl uding five diffe re n t s ty les: the Ultra s lim , Co mpact , CHOICE: is individually configured in our Singapore factory to your orde r -- "burn t in" for a full 48 hours, then air freighted direct. We fi nd any problems - not yo u! QUALITY: Superb quality: Just have a look inside and outside an IPC Computer. Not a co llecti on of bit s a nd pieces fro m vario us suppliers: we at IPC pri de o urse lve s in d es ign in g a nd m a nu fa cturin g almost everything ourselves (di sk drives excepted !). We also put it all together ourselves - al most by hand - wi th painstaking quality contro l at every stage! Regular, Tower and the new Desktop Tower cases. What more could yo u want? THERE'S MORE! The new IPC Point-Of-S ale terminal (POS)is now ava ilable . At last a PC-based POS at an ._ affo rdabl e p ri ce . Full y en g ineere d and developed by IPC. it's ready to revolutionise retail po in t- of-sa le a pplicati on s. De aler e nqu iri es m os t welcome! AND EVEN MORE! IPC are contin uall y developing new systems to add to the range. As the microcomputer world changes, IPC has the adaptabili ty and technica l expertise to change with it. GUARANTEE: O ur 30 Day Sati sfaction Refund Guarantee is just that: guaranteed' If yo u ' re not absolutely delighted with yo ur IPC Computer, return it and we ' ll give you your money back! Yo u' ll owe us nothing - not even an explanation. WARRANTY: -- O ur IPC Total Care Warranty is just that: On Site Total Care (with absolute maxi- mum 24 h o ur response) . And it ' s backed by the world ' s largest computer support company: B ull HN (formerly Honeywell Bull ). ..... - ----- - -.... .-..... _...,,, IPC Computer Systems A div is i on o f CompuHelp Aus t ra l ia ···························································-. WANT TO KNOW MORE ABOUT IPC? : Ask for our FREE informat ion pack. No obligation, no pr essure : just : a ll you need to know abo ut Austra lia ' s best value co mpute rs: . Name: .. ... .... .... .... ..... ..... .. ... ..... .. ..... .. .... ..... .... ........ .. .. ·· ···· ····· ····· ··· ·-··· ·· , Address: .... ............. ....... ....... ..... .... ... ......... . ... .. .... .... ... ........ ... • ........ ...... .. ...... ....... . ..... .Postcode:... ... .... ..... ..... ....... . I am intererested in [ ] XT [ J AT [ J NEAT Send to: l J 386 f ] POS CompuHelp Australia, 35-37 Higginbotham Road, Gladesville 2111. Tel (02) 809 6966 Fax (02) 808 3052 Or call in for an obligation-free hands-on demo nstration, ••••• ••• ••••••••••••••••••••••••••••••••••••••••••••••••••• .1 JULY 1989 FEATURES 6 A Day in the Life of A Computer by Ross Phillips ARE YOU WORRIED about exhaust gases seeping into your car with possible tragic consequences. If so, you need out Exhaust Monitor. Details page 14. A visit to the IPC factory in Singapore 10 The Facts On the PhaxSwitch by Leo Simpson The end of your fax machine hassles 82 The Evolution of Electric Railways by Bryan Maher Pt.21: the NSW 86 class electrics PROJECTS TO BUILD 14 Exhaust Gas Monitor For Cars & Vans by Bob Flynn Alerts you to carbon monoxide build-up 32 Extension For the Touch-Lamp Dimmer by Leo Simpson Let's you dim the lights from several positions 42 Experimental Mains Hum Sniffers by Steve Payor Build them from junkbox parts DIM YOUR LIGHTS from more than one position by adding this extension circuit to the TouchLamp Dimmer described last month. Construction starts on page 32. 58 Compact Ultrasonic Car Burglar Alarm by Greg Swain It's easy to build & easy to fit SPECIAL COLUMNS 28 Vintage Radio by John Hill Old Henry: one of my favorites 52 Serviceman's Log by the TV serviceman You need a pal to deal with PAL 66 Amateur Radio by Garry Cratt Build this intelligent charger for 12V gel batteries THIS COMPACT ultrasonic car burglar alarm is based on a proven commercial unit. It's easy to build and easy to install. See page 58. 70 Computer Bits by Jennifer Bonnitcha A look at video monitors 78 The Way I See It by Neville Williams Police radar: where it works & where it doesn't DEPARTMENTS 2 Publisher's Letter 4 Mailbag 22 Circuit Notebook 47 Bookshelf 87 Subscription Page 88 92 95 96 Product Showcase Ask Silicon Chip Back Issues Market Centre GET THE MOST out of your 12V gel batteries by building this intelligent charger. It's based on a single IC that constantly monitors the output voltage and charging current. Turn io page 66. ]ULY 1989 1 SILICON CHIP Publisher & Editor-in-Chief Leo Simpson, B.Bus. Editor Greg Swain, B.Sc.(Hons.) Technical Staff John Clarke , B.E.(Elec.) Robert Flynn Advertising Manager Paul Buchtmann Regular Contributors Neville Williams , FIREE, VK2XV Bryan Maher, M.E. B.Sc. Jim Yalden , VK2YGY Garry Cratt, VK2YBX Jim Lawler, MTETIA John Hill David Whitby Photography Bob Donaldson Editorial Advisory Pane l Philip Watson, MIREE, VK2ZPW Norman Marks Steve Payor, B.Sc., B.E . SILICON CHIP is published 1 2 times a year by Silicon Chip Publications Pty Ltd . All material copyright (c) . No part of the contents of this publication may be reproduced without prior written consent of the publisher. Kitset suppliers may not photostat articles without written permission of the publisher. Typesetting/makeup: Magazine Printers Pty Ltd, Waterloo , NSW 2017 . Printing: Masterprint Pty Ltd, Dubbo, NSW 2830. Distribution: Network Distribution Company. Subscription rate: currently $42 per year (12 issues) inside 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 manufacturing or selling of any such equipment. Address all mail to: Silicon Chip Publications Pty Ltd, PO Box 139, Collaroy Beach , NSW 2097. Phone (02 ) 982 3935. ISSN 1030-2662 * Recommended and maximum Australian price only. 2 SILICON CHIP PUBLISHER'S LE't-1ER Watch those resistors: they may not be what they seem Are you fully familiar with the resistor colour codes? Both the 4•band and the 5-band codes? For many years the first and biggest hurdle for the budding electronics enthusiast was to learn the colour code. Nowadays it is a lot easier because you can bypass the need to learn the colour codes by just using a digital multimeter. And if you are using close tolerance (eg, 1 % ) resistors with a 5-band code, trying to read the colours can be a bit of a pain. Why go through the mental gymnastics of translating the colour code when you can just whack the resistor across the multimeter and read off the value? If you are an enthusiast of several years' standing you may be rather disdainful of people who have to resort to a multimeter to check resistor values. Can't these people do a little mental arithmetic? After all, after you have acquired a little familiarity with the colour code, reading off resistor values becomes second nature, doesn't it? We happen to think that readers who are new to electronics do find reading colour codes difficult. So we are now listing the colour codes of every resistor specified in project articles. As well, in the first article of our ongoing series ''Electronics for Everyone'' , we recommended the use of a digital multimeter to check resistor values. We now believe, that with the vast numbers of Asian-sourced resistors on the market, that all resistors must be checked for value before use. Never mind what the colour code says, you still have to check the value. If you persist with the idea that you can read the colour codes and therefore you don't need to check values, you could be headed for trouble. In our recent experience, the colours don't mean much at all. For some time, it has been easy to confuse red bands with orange and green with grey but now it's worse. An orange band may really be yellow and what you think is a brown band could well be red. Only this morning, I soldered what I would have sworn was an 18k0 resistor into circuit only to have it malfunction. The resistor was actually 180k0 and yet the third colour band was unmistakably orange! It's about time the importers of these resistors did something about the colour codes. Why can't they be made to agree with those made by long established makers like Philips? Or is the reason really that the Asian makers don't know the colour code either? Anyway, you have been warned. Check those resistors with your multimeter before soldering them into circuit. Leo Simpson z DAVID REID W For the electronics enthusiast ELECTRONICS PTY. LTD. PLASMA BALL DISPLAY LIGHTNING AT YOUR FINGERTIPS This cosmic display will amaze you and your friends. Create beautiful swirling formations at the touch of your fingertips. It will also react to music via an internal microphone. ARLEC DIGI-SCALE • • • • DIGI-SCALE will measure from 1gm or 0.1 oz up to 2kg or 4Ib 8oz. Simply converts grams to ounces and ounces to grams by switching the selector key_ Various items can be individually weighed in the same container using the reset key_ 240 volt (plug-pack not supplied) or battery operated . 12 months warranty ONLY $59.95 WAS $199.00 This month receive FREE batteries to suit. NOW ONLY $150.oo AUDIO/VIDEO STEREO 3-WA Y SWITCHING BOX ONLY COMPUTER 2-WA Y and 4-WA Y SWITCH BOXES CENTRONICS TYPE 2-WAY now $49.00 4-WAY now $79.00 DB-25 TYPE 2-WAY now $49.00 4-WAY now $79.00 $49.95 • • • • This unit selects between three stereo audio/video inputs to one stereo audio/video output. It can also be used as a stereo audio only selector. All sockets are standard RCA sockets. Slimline designed cabinet. • Push-button selector panel. Complete with 3xRCA to 3xRCA connecting lead. 30 volt 1 amp POWER SUPPLY KIT • • • • • • • Output variable between 3 and 30 volts. Short circuit protection. Full 1 amp output over entire voltage range . Load switching. Output current - 0 to 1 amp (fully variable). Load regulation - better than 0.2% from O to full load . Output ripple - less than 2mV RMS. WAS $79.00 NOW ONLY $69.oo YES - WE HAVE THEM TOO!! MACHINED ALUMINIUM PERSONAL/PROFESSIONAL -~~ TORCH BY ARLEC l : • • • • ~1~:/~~: i~t~t"sity 5 Shock proof Removable torch head for 360 glow Spare globe supplied 1 2 months warranty ONLY $9.95 Also Includes batteries DAVID REID ELECTRONICS RS-232 BREAK-OUT BOX • • • • 1 0 signal powered LED 's for monitoring activities 24 DIP switches allow you to cut out or reconfigure 25 pin " D" plug to socket for in-line installation Complete with jump wires NOW ONLY $79.95 12 volt to 240 volt INVERTER 300 watt version • Complete kit . .. ..... was $279.00 now $269.00 • Fully built . . was $379.00 now $350.00 600 watt version • Complete kit was $425.00 now$399.00 • Fully built . .. was $525.00 now$499.00 40 watt version • This inverter is ideally suited to power low wattage mains appliances . • Kit only . now $85.00 LCD DIGITAL THERMOMETER • Temperature range: -40 to +50C • Presettable Hi-Lo alarm • Stainless steel probe with 1m cable • 1 sec/ 1 5 sec sampling cycle ONLY $39.95 127 York St, Sydney 2000 BUSINESS HOURS MAIL ORDERS Mon-Fri 8.30-5 .30 WELCOME Phone: (02) 267 1385 Thur 8.30-7 .00 PO Box 0103 Fax: (02) 261 8905 Sat 9.00-1.00 Sydney 2000 ESCORT EDM-55 PROBE MULTIMETER :~rn·· · · ·1\ _:__-p e 3.5 digit LCD display • • • • • Autoranging measurements Audib le continuity Diode fo rward voltage test Data hold AC/DC to 500V NOW $65.00 P+P RATES $5-$25 ... .... $4 $26-$50 . ..... $6 $51 over . .... $8 VIS4 MAILBAG Auxiliary brake lamps may be "el melto" I noted with interest your article on the flasher circuit for auxiliary brake lights in the April issue of SILICON CHIP. Here are two thoughts for consideration based on experience which may be of interest to other readers. Some of the cheap auxiliary lamps can be "el melto". I think it is a matter of luck. I put one on a Holden parcel shelf and after a couple of months it had started to sag. Actually the plastic was pretty poor quality for when I tried to remove the sales tag with methylated spirits the surface marred. Of the two types discussed the one which adheres to the rear window is the best. Those mounted on the parcel shelf reflect off the rear window at night, making it difficult to see what is behind you. I imagine it would be worse if the lamp was flashing, even briefly. S. Walker Grovely, Qld DC to DC battery charger has open circuit connection I have a comment on the DC-to-DC Battery Charger published in the September 1988 issue of SILICON CHIP. You may have covered it in notes & errata but I did not see it. As presented on page 79 of that issue the circuit will not function. The emitter of the output drive transistor within the LM3524, pin 11, is not grounded. Straight grounding without an emitter resistor will allow the circuit to work. In other respects the circuit works very well. J. Goode St. Clair, NSW Comment: right you are. Fortunately, the printed circuit layout presented on page 80 of the same article has pin 11 connected to the OV line, as it should be. Voltage regulation for alternators I would like to make a few belated comments about the review of the book, "The Homebuilt Dynamo" 4 SILICON CHIP which appeared in the October 1988 issue of SILICON CHIP. I ignored it at first since the reviewer obviously had had little practical experience with permanent magnet alternators. I have studied the theory and the practical construction of alternators for many years and consequently feel competent to point out a few home truths. (1). The Homebuilt Dynamo, as explained in the book's introduction, is basically 12 independently wired alternators using a common permanent magnet rotor. (2). Two wires from each of these "alternators" lead to separate fullwave rectifiers attached to an internal switchboard. As described in the book, the DC outputs are connected in parallel to give a combined output. (3). As described in detail in my book, I used the "dynamo" for charging a lead acid storage battery in a situation where I could control the revolutions per minute. (4). I thought it would be obvious to the knowledgeable reader that output control could easily be obtained where the resistance of the load (as in a battery charging situation) is going up or down by using voltage regulators to cut in or out as many alternator units as needed in parallel to match the load. A similar system is used in the AC mains electric distribution system to keep the voltage stable as demand varies. (5). Conventional permanent magnet alternators (which don't have separate stator units) can easily be voltage-regulated where the power source is relatively steady (such as small water turbine installations) by a simple electronic control unit called a "dump circuit" . It keeps the voltage on the output load constant by bypassing surplus power from the generator to a water heating unit, thus keeping a constant load on the generator. (6). In any electric generator it is true that by doubling the speed you approximately double the output voltage but this is only the no-load voltage. As soon as any current is drawn from the circuit, the impedance of the stator coil (which is SILICON CHIP, PO Box 139, Collaroy Beach 2097. always in series with the external load) subtracts some of the voltage across the external load. The ordinary bicycle dynamo is a simple example of a self-regulated permanent magnet alternator where the impedance of the stator coil (as the frequency rises) limits the voltage and current rise to the wattage of the headlamb bulb. No matter how fast you spin the dynamo, you won't burn out the light bulb. Alfred T. Forbes Oratia, NZ Wants January 1988 issue I notice that your January 1988 issue is no longer available. As I am endeavouring to obtain copies of all your issues I was wondering whether you know of anyone who may be prepared to sell an old copy. I am willing to pay $5 for even a secondhand copy. Mike Stephenson 12 Rickey Street Capalaba, Qld Comment: your request is typical of those we receive from time to time but we are not able to help directly, apart from publishing your Jetter and address. Our stocks of early issues are now low and when they're gone, they're gone. November 1987 is also no longer available. RF preamps for country reception Your magazine really is now an important one on the Australian scene. You try, successfully, to attract the attention of "experimenters and consumers", young and old. Better still, you seek a dialogue with your readers, as your April editorial clearly demonstrates. I would like to "pickup" the last paragraph of it. Many Australians, particularly those in country areas, suffer from poor radio/TV reception. The "loss" of radio is the more important as country areas, generally, receive two TV channels at best. For radio, many of us obtain reasonably good receivers, in the hope that we can secure interesting and consistent reception for our families. At an early stage, we also realise that aerial/receiver matching, or aerial/preamplifier/receiver matching is critical. Receiver manufacturers tend to recommend the input impedance their receivers accommodate best. Now comes the problem. How can these requirements be met, from say, the 50 ohm to 300 ohm inputs, let alone the so-called " hi-input" receivers'? In the country, RF preamps are virtually mandatory! If someone can be commissioned to provide an article which comprehensively covers the "matching" problems involved, I and many others will be most grateful. R.H. Barker Corryong, Vic Warning: your CD player could self-destruct! I recall an uproar from die-hard analog fans who were outraged by an editorial in another magazine which claimed that CD players were capable of much better performance than any turntable could ever produce. I was impressed by the fact that the editorial said the CD system itself was capable of the level of perfection and not that all CD players themselves could achieve it. It is true that there are some machines on the market which are pitiful while others do things vinyl could only dream of. As someone who owns over 150 CDs, may I say that I have no doubt at all that you can achieve better performance both sonically and mechanically from a $460 Philips CD player than you can from any turntable, regardless of the price it may have. Already I hear faint gasps of horror! But what really shocked me was when I was perusing through a CD store recently and spotted a comment on the label cover of a recent release album that stated, and I quote: "Playing pirated CDs can damage your player and equipment" . Now the analog mob have really outdone themselves, or is this the work of greedy digital fans'? What 's going to happen if you play a pirate brand disc'? Is the machine going to enter a 10 second countdown then self-destruct'? Is it going to jump out of the hifi rack and throw itself on the road in front of a truck or perhaps hold my amplifier for ransom'? As if the public isn't confused enough, trash like this is bound to create even more havoc. . However I'm proud to have been a SILICON CHIP subscriber since the very first edition and look forward to continuing the relationship for many years to come. Keep up the good work. S. McBride Townsville, Qld Programs for VCRs with digital scanners I have just read the April 1989 issue and, in the "Serviceman's Log", two points caught my interest: (1). In mentioning the Panasonic G-40 VCR, he notes that this unit is supplied with a digital scanner but says he has yet to see any published programs featuring the required bar pattern. Here in Christchurch, a city of approximately half a million people, both daily newspapers print bar codes for a selection of programs and they are also printed in the TV guides. In addition, the G-series models with scanner are supplied with a programming sheet for programming any particular program for which no code was printed. This is supposed to be easier than pressing buttons on the VCR. In practice, some people have difficulty with the scanner, which must be held perfectly vertical and moved across the code at a certain, constant speed. Having tried various systems, the best system I have yet seen for programming is the on-screen system fitted to the Mitsubishi E-series (ElO, E20, E30, E70). (2). He notes that when a cassette is inserted, the tape is loaded against the control head, and ventures to suggest that this is to provide better control of loading. The real reason is quite different. More modern videos, including the latest G series and Mitsubishi E series, among others, have dispensed with the mechanical 4-digit tape counters and use a linear time counter instead (counting in hours, minutes and seconds). To provide this facility, the unit counts the control track pulses on the tape; hence, the tape must be against the control head at all times whilst the tape is loaded in the machine. (Obviously, the counter will not count when reading the non-existent control track on a new tape). The newest machines (Mitsubishi E series) take this a step further and will automatically load the tape around the heads when a tape is inserted; hence, when PLAY or RECORD is pressed, there is only a 2-second delay while the tape starts moving, rather than the additional delay that would be required while the tape was loaded around the heads. When FF or REW is pressed, there is naturally a delay while the machine unloads the heads before winding can take place. Apart from providing linear counter functions with the control track, this system can also provide the index search and address search functions that are found on modern VCRs. This is carried out by modifying the pulse width of the control track pulses (duty cycle) which allows the pulses to be coded as 0s and ls. Thus indexing and addressing signals can be put on the tape. Another feature which is of interest, provided on the Mitsubishi Eseries, is the Tape Remaining display. This shows the hours and minutes of tape remaining (typically 3 hr 2 min on an E-180 cassette, or 6 hr 4 min in longplay mode). I have not managed to work out how this works - one theory is that the unit drives one reel at a known speed and then times the speed of the other reel. Certainly, it is very accurate. As editor and publisher of a monthly newsletter for one of the local railway enthusiast groups, I commend you on your series of articles on the "Evolution of Electric Railways" . Of particular interest were the articles on early diesels and that on the Queensland 25kV AC electric locomotives (very similar to the locomotives being used on our North Island Main Trunk electrification). Incidentally, on the Ferrymead Railway in Christchurch, we have the 1500V DC electrified catenary and four electric locomotives plus an electric multiple unit, running on what is believed to be the only electric railway museum in the southern hemisphere. P. Dunford Christchurch, NZ JULY 1989 5 A (Birth)Day In The Chances are, these days, one of the first things you do when you arrive at work is use a computer. Ever wondered just how that computer came into being? By ROSS PHILLIPS To the general public, even in 1989, computers are rather formidable devices. To those with a technical "bent", they're rather less frightening but most of us still think of a computer as a "black box". SILICON CHIP has a large proportion of readers whose interest goes more than skin deep. So we thought you'd like to go behind the scenes and visit a computer manufacturer. As well as the several locally manufactured computers, there are literally hundreds of brands being made around the world. Most come from Asia: Taiwan and Korea, Hong Kong, Japan, even China. And most have similar methods of production, with various degrees of automation. Singapore, also, has a thriving computer industry - and when the opportunity arose for someone from SILICON CHIP to visit Singapore's leading computer manufacturer, we naturally said yes. The company, Essex Electric, makes a range of IBM compatible computers under the "IPC" brand (the letters standing for Intelligent Personal Computer). A small proportion of their production is for the Singapore market but the vast majority - over 1000 per week are destined for distributors throughout Europe, Asia, Australia and New Zealand. The first thing that struck us about the Essex Electric manufacturing facility, located approximately half way between the business centre of Singapore and Changi (of War Prison and later in- ternational airport fame), is the lack of salubrious surroundings. However, we soon learned that this was typical of Singapore; apart from the fact that every square centimetre of land is precious (meaning factories are high rise for the most part), the tropical climate makes painting the buildings a waste of time and money. No robots Another surprise was the lack of automation. No robot assembly lines here: IPC computers are made almost entirely by hand apart from flow soldering of the PCBs. However, labour in Singapore is relatively cheap compared to, say, Australia: the average worker in a factory earns around S$1000 to S$1200 per month (A$700 to A$800). Hence labour intensive industries can succeed where they would not elsewhere. But we're jumping ahead of the story. Let's go back to the start. Essex was formed in 1980 by two brothers who graduated in electronic engineering from the University of Essex (UK). Initially set up as a specialist printed circuit board manufacturer, it now concentrates entirely on the making of computers and related products. In fact, the original PCB manufacturing facility was sold off in 1984 - and Essex has remained its largest customer. The philosophy has always been "quality first" . The company made a decision very early in its life not to cut corners to save money. Research and development READY FOR ASSEMBLY: a blank PC board is placed on a conveyor belt so that the sockets and passive components can be fitted. The boards are pre-baked in an oven to force out every last smidgin of water. 6 SILICON CHIP This attention to quality becomes obvious in the research and development department. No pressure is applied to the team of engineers to produce faster - even if it takes a little longer, management knows that the designs coming from R&D will be optimum. While we were there, a team of engineers was working on the next Life Of A Computer in microns, not millimetres! When completed, a copy of the CAD software is sent off to the PCB manufacturer, who has the ultraprecision plotters necessary to convert it to film. Completed boards are delivered back to the factory hermetically sealed and each one is visually inspected for flaws. PCB assembly AFTER THE PASSIVE components have been fitted, all the ICs (with the exception of the RAM chips) are installed. The earth strap fitted to the worker's wrist protects the ICs from static electricity. Essex product, a point-of-sale (POS) terminal suitable for everything from the smallest motel or service station through to the largest retail chain. The enthusiasm of the design team was infectious: before we left the laboratory, we were firmly convinced that the Essex POS terminal will be the greatest thing since sliced bread! Many prototypes are made of each design. Every one is subjected to " worst case" analysis to allow for component tolerances well in excess of what could be expected. Many are tested to destruction. PCBs are designed, tested and retested. Layout is done with the aid of a $300,000 CAD system, and in some cases extends to a 6-layer board. Track widths are measured Immediately before assembly, each board is baked in an oven to force out every last smidgen of water - particularly from the component holes. This simple step virtually eliminates dry joints when the boards are later soldered. The boards are assembled in two stages on one production line. First of all, the sockets and many of the passive components are inserted, then the active components, crystals, etc are inserted, all by hand. Components purchased for use in the Essex plant are top quality, prime spec devices. Even then, all batches are randomly sampled by quality control. If any devices are not to spec, the whole batch is rejected. It is perhaps fortunate that the modern computer board uses so ABOVE: WHEN DRY, the boards enter an automatic testing station before passing to the next stage of assembly. LEFT: AFTER FLOW flow soldering, the still hot board is dunked in a bath of pure water! JULY 1989 7 FOLLOWING THE AUTOMATIC testing station, each board is powered up and run for a full 24 hours in an enclosed cupboard. The heat build-up inside the cupboard further stresses the components and shows up any faulty boards. few components: a completed board emerges from the assembly line every few minutes. Once the board has reached the stage where static damage-prone devices are involved, all workers on the line are earthed to both the board and a common earth via wrist straps. Immediately before the flowsoldering machine is a quality control officer, who visually inspects all boards and pushes down all ICs, sockets, etc to ensure they are fully "home". We weren't quite ready for the next stage of production: as each board leaves the flow-soldering machine, while it is still hot, it drops into a bath of pure water. That's right, each board is immersed in water - for a period of about five minutes! The quality control manager explained that this is one of their most important tests. Because the board is still hot, the cold water causes a mild shock to every component and solder joint. As any serviceman will tell you, it's those dry joints which get you: often years later. The shock of the cold water bath shows any suspect joints immediately - no waiting! But that's not all: each board is then thoroughly washed in a hot water spray. This removes any flux or solder residue and again places the board and its components under high stress. The pre-baking and the water bath between them have virtually eliminated dry joints in this factory. Assuming the board has passed this stage, it is then dried off with compressed air, then thoroughly baked for several hours to completely dry it out. After drying, the boards are placed on another chain conveyor where component _pigtails etc are removed by a high speed rotary saw. Finally, each board is given close visual inspection by another quality control officer before being passed through to dynamic checking. More quality control Each board then enters a 100% component and operation check in a fully automatic testing station. The PCB is placed in a jig, and is brought into contact with many hundreds of "fingers". Under computer control, every facet of operation is checked in just a few moments. The readout on the computer screen is simple: "good" - everything passes, or "bad" - a ABOVE: AFTER FINAL assembly, the computer, together with its monitor and keyboard, is checked for a full 48 hours in the "burn-in" room. LEFT: A TECHNICIAN examines a reject board from the automatic testing station. If a faulty component is the cause, it is replaced on the spot and the board re-enters the test procedure. 8 SILICON CHIP single failed test procedure means rejection. In fact, the computer testing procedure will print out a report indicating to the technicians which component or area of operation is faulty, making the subsequent repair simple. If a PCB is repaired, it re-enters the testing procedure as if it had just come from assembly. 24-hour burn-in Each PCB is then powered up and run for a full 24 hours in a specially designed cupboard containing perhaps 20 or 30 other boards and power supplies. Because the cupboards are fully enclosed and insulated, the heat build-up is high - subjecting the components to further stress; far more than they would be expected to undergo in normal life. Final assembly If the PCB gets the nod from quality control, it is then stored in a controlled atmosphere ready for final computer assembly. As the computer is assembled, the memory, disk drives, display cards, etc, as specified by the customer, are fitted. The "customer" is not the distributor: he or she is actually the end-user customer. For example, a customer in Australia might order a "NEAT (286) type with 4Mb memory, 40MB 28ms hard disk, 1.2MB 5¼in and 1.44MB 3½in floppy drives, and VGA graphics, in a desktop tower case". The local distributors, CompuHelp Australia, would fax this order direct to Essex in Singapore, and a work sheet would be prepared immediately listing that configuration. Each component necessary to build the computer to those specifications would be taken from the store, and routed through to the final assembly area. Around 20 technicians are involved in assembly and each one can complete a computer in around half an hour. So, depending on the hours worked, the factory has a production capacity of between 250 and 300 hand-built computers per day. THE FINISHED PRODUCT: this particular machine uses the new enhanced AT chipset and runs at 20.5MHz in turbo mode. It is equipped with a 5¼-inch 1.2MB floppy disc drive and a 40MB hard disc. When completed, the technician will power up the machine and test basic operation. He will then format the hard disk, load DOS [the disk operating system) and ensure the computer is fully operational. When the technician is satisfied with his handicraft, he despatches it to the final stage of production, the 48 hour burn-in room. Here, every computer is "married" to its appropriate video monitor and keyboard, and all are checked for a full 48 hours with a series of diagnostics and routines that cycle through every component. Only if the computer system passes through every check with 100% success is it considered now finished. Each of the quality control check-lists stays with its computer until delivery to ensure nothing is left to chance. Despatch While the computer might be electronically finished, it still has to be prepared for the rigours of transport. Specially designed foam [not styrene) packaging holds the computer firmly and securely within its transportation box, which also contains the keyboard and manuals. The monitor is packed separately. Normally, computers are despatched by air, meaning the customer doesn't have to wait any longer than necessary for his or her machine. ~ JULY 1989 9 The facts on the PhaxSwitch ,n o you need to share a telephone with your fax machine? Many people do and it can cause hassles. Now there is a brilliant new product which lets you receive faxes automatically and yet still allows you to use the phone in the normal way. By LEO SIMPSON 'fhe product in question is the PhaxSwitch, made by Banksia Information Technology, the people who produce the Bit Blitzer modems and other computer peripheral products. Up until now, sharing a telephone line with a facsimile machine has presented a problem. If you put the fax machine into the "auto answer" mode, it is not possible to receive phone calls and the dialling party gets a loud fax tone in the ear - quite off-putting to say the least. Or if you leave the fax machine in the manual mode, you have to rush to the phone every time it rings. This can be particularly annoying if the incoming call is really a fax. PhaxSwitch solves this problem 10 SILICON CHIP beautifully. You plug the incoming telephone line, your fax and your phone into the back of the PhaxSwitch, power it up and you are set. It has three modes of operation, selectable by a rocker switch on the diminuitive front panel: Phone, Auto and Fax. In the phone mode, all incoming calls are "picked up" by the PhaxSwitch. If it hears an 1 lO0Hz tone on the line, it automatically switches the call through to the fax machine. If it does not hear the tone, it switches the call to the phone. Sounds simple, doesn't it but since it has already picked up the call how does it sound the bells inside the phone so that you know there is a call waiting? The answer is that it generates its own ringing voltage so that the phone rings in the normal way. You then pick up your phone and answer as usual. If the calling party is using a manual fax machine and pushes the button to start transmitting, the Phax Switch will again recognise the tone and switch it through to the fax. And of course, you can make calls and send faxes in the usual way. Auto mode If the ''phone'' mode sounds fancy, consider the "auto" mode. Here the PhaxSwitch automatically switches through calls made on autodialling faxes. On other calls it answers with this voice message: "This is a BIT PhaxSwitch answering your call. If you want to send a fax, say 'fax' after the tone otherwise wait until the phone is answered''. If the calling party says 'fax', the call is immediately switched through to the fax machine. If not, the phone rings until answered. Is that not mind-boggling? Not only does the PhaxSwitch have its own synthesised voice message, it also has voice recognition circuitry. Plus it has all the fancy bits and pieces to allow it to switch calls, ring the phone and so on. It can also distinguish between NEC faxes and standard fax machines. NEC fax machines initially send out a 900Hz tone instead of the 1 lO0Hz mentioned above. If another NEC fax hears this 900Hz tone, they go through a shorter "hand-shaking" routine and so the fax message goes through more quickly. So the PhaxSwitch can recognise these two different fax machines without problems. Taking a look inside the unit reveals that it is a very complex piece of equipment, chock full of electronics. It uses three relays, four transformers and no less than 10 optocoupler ICs plus a number of custom ICs and a host of other prosaic bits and pieces. How it all works is a complete mystery but obviously there is some pretty fancy programming in those custom chips. On the rear panel, it has a socket for 9.3V AC power and three US modular phone sockets: one for the incoming phone line, one for the fax and one for the phone. How it performs We found that the unit works very well on our own shared fax/phone line but with one big problem. Some of the older telephone exchanges in Australia emit a 900Hz tone for STD calls instead of the 500Hz tone from newer exchanges. When we received calls from one of these older exchanges, they were automatically switched through to the fax whether they were faxes or not. When contacted about this fault, Banksia Information Technology immediately swung into overdrive to solve the problem. It turned out that the number of exchanges involved is small but unknown apparently even Telecom wasn't able to give the number. The design engineers then had to modify the software so that the PhaxSwitch could distinguish 900Hz STD pulsed tones from the 900Hz continuous tone emitted by NEC faxes. They had a definitive cure within a few days and then The fax switch is chock full of electronics. It uses three relays, four transformers and 10 optocoupler ICs, plus a number of fancy custom ICs to provide such features as voice synthesis and voice recognition. had the problem of modifying many units out in the field and those ready for delivery. They certainly can move very fast - an indication of good customer service back-up. With that modification now complete, the PhaxSwitch is an excellent product which will fulfil a crying need, especially in country locations where the cost of installation for an additional phone line can be horrendous. And even if you live in the city, the PhaxSwitch will pay for itself very quickly by avoiding the rental cost of an additional line . We think it's a marvellous product. Where to buy it Our sample machine came from Dick Smith Electronics who have the PhaxSwitch available at all stores . Their selling price is $379.00. Dealer enquiries should be directed to Banksia Information Technology (Australia) Pty Ltd, PO Box 1200, Lane Cove NSW 2066. Phone (02) 418 6033. ~ ]ULY 1989 11 -.,_ -- M0TH ERBOARDS IBM PC/XT COMPATIBLE TURBO 10MHZ MOTHERBOARD -Expandable to 640K RAM using 4164, 41256 & 41464120ns chips -4.77 or 1OMHZ hardware or keyboard selectable operation -Front panel LED indicators supported -Eight expansion bus slots -AMI BOIS ROMs included -8087-1 Math co-processor capability -Performs_at an average speed of 100% faster than the original IBM PC/XT -Norton SI rating of 2.0 -Size (12" x8.5") -Weight (1.75Ibs) $149 IBM PC/XT TURBO 8MHZ MOTHERBOARD -Expandable to 640K RAM using 4164 and 41256, 150ns chips -4 .77 or 8MHZ hardware or keyboard selectable operation -Front panel LED indicators supported -Eight expansion bus slots -AMI BIDS ROMs included -8087-2 Math co-processor capability -Performs at an average speed of 75% faster than the original IBM PC/XT -Norton SI rat ing of 1.7 -Size (12" x 8.5") -W~ight 1.75lbs $139 IBM AT COMPATIBLE 12MHZ 80286 MOTHERBOARD -Expandable to 1MB RAM using 256K DRAM chips -Expandable to 4MB RAM using 1MB DRAM chips -Expandable to 2.5MB RAM using a combination of 256K and 1MB DRAM chips -8 or 12MHZ hardware or keyboard selectable operation -Front panel LED indicators supported -Six 16-bit and two 8-bit expansion bus slots -AMI BIDS ROMs included -Zero wait state -Selectable RAM chips speed (80 or 100 nanosecond) -80287-8 Math co-processor capability -Norton SI rating of 13.7 -Size (13" c 8.75") -Weight (2.25lbs) $499 NEAT---MOTHERBOARD $795 -N rton SI ratin of 15.6 KEYBOARDS IBM PC/XT/AT COMPATIBLE KEYBOARD CASES -101 Key -Enhanced keyboard layout -Tactile touch keyswitches -12 Function keys -lluminated LED indicators for Num Lock, Caps Lock and Scroll Lock -Separate cursor pad -Low profile design -Automatically switches between PC/XT or AT -Manual included -Colour beige (19"w x 8"d x 1.33"h) -Size $109 -Weight (4.6lbs) 84KEY $99 8088 BABY8088 BABY80286 GRAPHICS CARDS MONO PC/XT/AT $109 CGA $115 $299 EGA $99 $129 $129 POWER SUPPLIES IBM AT COMPATIBLE 200W POWER SUPPLY -Input <at>47 -400Hz (110/240V switchable) -Output +5v<at>20A. -5V<at> 0.5A. +12v<at>8A. -12v<at> 0.5A -Plug compatible connectors -Built in fan -Spee included POWER -Size (6.5"1x 5.88"w x 6"h) $199 POWER SUPPLY $125 150W -Weight (6lbs) SUPPLY 150WBABY -Size 6.25" x 6" x 6" $145 CONTROLLER CARDS 360KBn20KB/1.2MB/1.44MB FLOPPY DISK DRIVE CONTROLLER CARD FOR IBM PC/XT/AT AND COMPATIBLE COMPUTERS -Allows connection of one or two 360KB. 720KB. 1.2MB or 1.33MB floppy disk drives . Includes cable for two internal disk ~ ~ ~ - 1. FLOPPY DISK DRIVE CONTROLLER CARD FOR IBM PC/XT AND COMPATIBLE COMPUTERS -Run up to four 360KB disk drives -Includes cable for two internal drives -DC37S connector allows for an additional two external drives (external cable not included) -complete with manual $55 MFM HARD DISK CONTROLLER CARDS FOR IBM PC/XT/AT AND COMPATIBLE COMPUTERS -8 bit MFM hard disk controller card for the 1MB PC/XT and compatible computers. Can be used with many types of hard disk drives. Cables and documentation included. $139 HARD DISK/FLOPPY CONTROLLER FOR IBM PC/XT AND COMPATIBLE COMPUTERS - 8 bit floppy and MFM hard disk controller for the IBM PC/XT and compatible computers. It will allow connection of up to two hard disks and two floppy 360KB drives . Cables are included to allow connection of one hard disk and two floppy disk drives. To connect a second hard disk drive an additional cable will be requ ired. $175 HARD DISK/FLOPPY CONTROLLER FOR IBM AT AND COMPATIBLE COMPUTERS - 16 bit floppy and MFM hard disk controller for the IBM AT and compatible computers. It will allow connection of up to two hard disk drives and any combination of two floppy disk drives. To connect a second hard disk drive an additional cable will be required. $245 MFM HARD DISK CONTROLLER CARD FOR IBM AT AND COMPATIBLE COMPUTERS - 16 bit MFM hard disk controller for the IBM AT and compatible computers . It can be used with many hard disk drives. Cables are included. $220 , Service /,f' the difference Over 15 years mail order experience How to order: Phone (021418 6711 and quote your Bankcard, Visa or Mastercard OR send your Mail Order directly to PC Marketplace with your cheque, money order etc. (NO cash please) All prices are subject to change and w ill be guaranteed for present stock . Unless insurance is requested goods are sent at customers own risk. 14 Day money back guarantee except on: Semiconductors, Software, Books & Special Orders 1/0 CARDS RS232 HALF CARD FOR IBM PC/XT AND COMPATIBLE COMPUTER -Fits the difficult to use half card slot or any long slot -RS232 card comes with one ready to go serial port -Expandable to 2 ports by user (parts for expansion not included) -Selectable for COM1 thru COM4 -The user is able to select addresses for ports A and 8 as well as interrupt requests -Manual included $55 1/0 CARD FOR PC/XT W/GMS CLCK $125 1/0 CARD 2 PORT $65 FOR AT 1/0 CARD FOR AT $125 WITH GAMES MULTI 1/0 CARD WITH MONO GA $229 MULTI 1/0 CARD $149 MEMORY CARDS 2MBYTE MEMORY EXPANSION CARD FOR IBM AT AND COMPATIBLE COMPUTERS -Utilizers (72) 41256-120ns chips for the full memory capacity of 2Mbytes -Offers conventional expanded and extended memory capabilities -Features auto-parity check -EMS compatible driver _RAM disk and print spooler software included $245 MEMORY CARD PC/XT for 640K $99 Power Cable Y for disk Adaptor 09F-025M Adaptor 3.5" power cable adaptor Serial Printer/Modem C81 8ft Parallel Printer Cable - straight 12ft Parallel Printer Cable - straight 6ft Parallel Printer Cable - right angle Modem/Printer Cable Serial Cable for AT Floppy Cable 5.25' C34 Internal Floppy Cable 3.5/5.25" Internal Floppy Cable 037 External HOD Cable 34 way HOD Cable 20 way Serial Shielded Cable M-F Serial Shielded Cable F-F Centronics Shielded F-F Centronics Shielded M-M $5.95 $9.95 $5.95 $19.95 $12.50 $15.00 $19.95 $19.95 $19.95 JAPANESE DRIVES 3.5" 1.44M/720K Switchable between 1.44/720 OS/OD 3.5" Mounting $225 5.25" mounting $249 5.25" 360K Drive 500K unformatted XT compatible $179 5.25" 720K/1.2MB Drive To 1.6MB unformatted AT compatible 5.25" 40MB Hard Drive 50MB unformatted. 28ms average seek time $695 MONITORS 12" TTL Green $179 12" TTL Amber $179 CGA 14" TTL Colour Philips 2 year guarantee. Stereo sound suits PC and Amiga $525 EGA 14" TTL Colour $649 FOR DETAILS ON OTHER PRODUCTS PLEASE RING. 88FF 0825S (socket) to 0825S (socket) 88MF 0825P (plug) to 0825S (socket) 88MM 0825P (plug) to 0825P (plug) These boxes will allow you to design new interfaces or modify old ones. The boxes come complete with (25) 22AWG jumpers and machine tool sockets so you are sure to have a good connection. They are completely selfcontained and are available with either male-male, male-female or femalefemale 0825 connector Bus mouse frees your serial port. The Bus Board installs easily in a half slot in your computer and leaves your system's serial port free for other peripherals. $149 ALL$19.95 MULTILINK RS232 TESTER AND BREAKOUT BOX Allows cable makers to configure custom cables. The MLA 1 will visually let you know status of lines 2,3.4,6,8.20 and 22 on the DTE and DCE side by ulitizing red/green bi-colour LEDs. The MLA1 provides you the signal status at a glance (four states: mark, space, clocking and off). Complete cable "breakout" and reconfiguration exists with 24 in-line switches and 54 in-line machine tool sockets. Includes handy carrying case, 10 jumper wires and a device wiring chart. Cable extends 4 inches from side of tester. Connectors; One male 0825 and one female 0825. With the MLA 1 you can easily see if a line is: High (+6 to +25V) bright red led; High (+3 to +6V) dim red led; Low (6 to -25V) bright green led; low (-3 to 6V) dim green led; Off (-3 to +3V) led off. $49.95 SCANNER Logitech Scanman Hand-held scanner for IBM PC/XT/AT & PS/2 and compatible computers. $399 $12.50 $12.50 $19.95 $12.50 $9.95 $19.95 $19.95 $19.95 $19.95 LOGITECH BUS MOUSE -Manual included $229 LEADS & ADAPTORS RS232 BREAKOUT BOXES LOO PBACK TESTER $14.95 MINI TESTER $14.95 CHECK TESTER $19.95 FREIGHT CHARGES Include $10 with order for all normal items - heavy items, e.g. monitors add $1 5. GENDER CHANGERS MALE-MALE $9.95 FEMALE - FEMALE $9.95 MOUSE PAD Cleans, protects and prevents wear on your mouse's roller ball. Sensitive, accurate and prevents dirt contamination. Tough non- skid neoprene backing with smooth gliding anti-static plastic coating on top surface. -Size (11'1 x 8.5"w) $7.50 PERSONAL COMPUTER MARKETPLACE Pty Ltd PHONE (02) 418 6711 Mail Order Address P.O. Box 1100 Lane Cove NSW 2066 VISA HIREZ BUS MOUSE FOR IBM PC/XT/AT/2 (MODEL 25,30) AND COMPATIBLE COMPUTERS The new LOGITECH High Resolution Mouse is the only mouse designed expressly for today's new generation of high resolution displays, such as EGA, super EGA and VGA. The mouse is ideal for desktop publishing as well as CAD applications. With 320 dots per inch (dpi) resolution (compared with 100 or 200 dpi mice), the LOGITECH HiREZ covers the same area on your screen, but uses 62% less desk space to do it. This saves you valuable desk space, and effort. Mouse maneuvers that used to require a sweep of the hand are now reduced to a flick of the wrist. lnclLJ:Jes Plus Package software with mouse drivers, text editor, menu building and point-click software (Lotus 1-2-3). -Size (3.8"1 x 2.7"w x 106"h -Colour light grey $179 LOGITECH MB MOUSE FOR IBM PC/XT/AT AND COMPATIBLE COMPUTERS The Logitech MB Mouse features opto-mechanical technology at acompetitive price. This new twobutton mouse requires one male 0825- pin serial port and comes with a female 0825 cable assembly. A 0825 to 0B9 adapter (AD925) may be needed if the serial port you plan to use has a male 089 connector. The mouse comes standard with a six foot cord and features 200 dpi resolution. -Colour Iight gray -Size (3.8"1 x 2.7"w x 1.06"h One year warranty $99 Exhaust gas monitor for cars & vans Are you worried about exhaust gases seeping into your car with possible tragic consequences? If so, you'll be interested in this project. It's an exhaust gas monitor that can be fitted to any van or car and sounds an alarm in the presence of exhaust gases, particularly carbon monoxide. By BOB FLYNN & LEO SIMPSON Do you get a headache during or after a trip in your car or van? Is it a slight frontal headache or a real head-splitter? Either way, you could be suffering from the effects of exposure to carbon monoxide. There are two easy ways that you can be exposed to this utterly colourless, odorless but very deadly gas. First, you may be driving in slow "bumper to bumper" traffic. Because so many cars are close together with their engines running 14 SILICON CHIP at idle, it is inevitable that you will be breathing exhaust gases, either from the cars in front, at the sides or even from your own car. And if you have your airconditioner on the "fresh air" setting, the effects may be worse than if you drive with your window open. Second, if the rear door of your van or the boot of your car does not seal properly, exhaust fumes will be sucked in at the rear of your vehicle as you drive along. And con- trary to what you may think, opening the windows may not make very much improvement. So while you are driving along seemingly unaffected, your rear seat passengers could be getting a very bad dose with possible fatal consequences. Don't think that just because your exhaust system is not faulty that you are safe. Normally operating vehicles can produce lots of carbon monoxide, sufficient to put you and your family in great danger. Table 1 shows the effect on humans of various concentrations of carbon monoxide in air. Note that these are mostly short term effects (apart from death which is a long term effect). An interesting point to consider here is that people often associate dizziness and nausea with "car sickness" or "motion sickness". However, if you look at the modest concentrations of CO in Table 1, it is quite possible that what is often blamed on "car sickness" could be a good dose of carbon monoxide. Why is carbon monoxide so dangerous? The reason is that it combines with haemoglobin in the blood and stops it carrying oxygen. If enough haemoglobin in your blood is affected, your brain will suffer from oxygen starvation. As Table 1 shows, quite modest concentrations of carbon monoxide can spell real danger. This is because carbon monoxide has over 200 times more affinity with haemoglobin than oxygen. In severe cases of carbon monoxide poisoning, a blood transfusion is the only way to save the victim from death. And what of the long term effects of frequent exposure to modest levels of carbon monoxide? At the time of writing this article, we had no information on this aspect but we would not be surprised if there were adverse effects. The risk of exposure On a number of quite new vans and cars SILICON CHIP has examined, the rear door or boot lid did not seal properly because the rubber TABLE 1 Concentration of CO In Air Toxic Symptoms Developed 0 .02% (200ppm) Slight headache within 2 to 3 hours. 0.04% (400ppm) Frontal headache within 1 to 2 hours, becoming severe within 2.5 to 3 .5 hours. 0.08% (800ppm) Dizziness, nausea and convulsions within 45 minutes; insensible within 2 hours. 0.16% (1600ppm) Headache, dizziness and nausea within 20 minutes; death within 2 hours. 0 .32% (3200ppm) Headache, dizziness and nausea within 5 to 10 minutes; death within 30 minutes. 0.64% (6400ppm) Headache, dizziness in 1 to 2 minutes; death in 1 0 to 1 5 minutes. 1.28% (12,800ppm) Death in 1 to 3 minutes. gasket was defective or nonexistent (quite common on courier vehicles) or the catch was out of adjustment. In addition, many Japanese vans have a battery compartment in the floor of the rear compartment. Often, this is inadequately sealed and lets exhaust fumes in. As these vehicles are driven +12V TGS812 GAS DETECTOR 10k 2.2k .. SENSITIVITY ADJUST VR1 20k 100k .,. 4.7M 4700 .,. OSCILLATOR 3.9k TURN ON DELAY +5V +12V 120k 39011 +12VC>-<) 100 1.. + .. + 16VWJ .. 120k CAPACITANCE MULTIPLIER 10 0.11 0.1l 16VWJ POWER LED2 GREEN .,. B 100 + 16VWI LL - ,. EOc VIEWED FROM BELDW -~- ~K GND EXHAUST MONITOR Fig.1: when gas is detected, the resistance of the TGS 812 sensor drops and pin 7 of IC1a goes high. This allows oscillator IC1d to run and thus pulse the alarm on and off via transistor Q2. IC1h & IC1c mute the alarm for 2 minutes when it is first turned on, to give the heater time to purge the sensor. ]UL Y 1989 15 Fig.2: here's how to install the parts on the PCB. The TGS 612 sensor can be installed either way around but note carefully the orientation of transistors Qt and Q2. The 7605 3-terminal regulator is mounted on the copper side of the board. 12V METALLISED POLYESTER CAPACITORS + 5.6 0 □ COPPER SIDE OF BOARD) Value 0.1µF IEC EIA 1 OOn 104Z RESISTORS □ □ □ □ □ □ □ □ □ □ □ □ No. 1 2 3 2 1 1 1 2 1 1 1 Value 4 .7MO 120k0 100k0 10kn 4.7k0 3 .9k0 2 .2k0 1 kO 4700 3900 1800 5.6n along the road they will quite naturally suck in their own exhaust fumes and, as our tests showed, you can't guard against this simply by opening the windows at the front. The only remedy in this case is to stop the vehicle and fix the leak. But what if your boot lid or rear door is sealing perfectly? Are you safe from exposure to the carbon monoxide in exhaust gases? No you are not. If you are driving in traffic or stopped at traffic lights with other vehicles, you are bound to be exposed. This applies particularly if you drive with a window open or with your air-conditioning set to "fresh air". In these circumstances you should set the air-conditioner to "re-circulate". So whether or not your vehicle has defective seals, you still need an exhaust gas monitor to tell you that you are exposed. Exhaust monitor With these problems in mind, we 16 SILICON CHIP 4-Band Code yellow violet green gold brown red yellow gold brown black yellow gold brown black orange gold yellow violet red gold orange white red gold red red red gold brown black red gold yellow violet brown gold orange white brown gold brown grey brown gold green blue silver gold 5-Band Code yellow violet black yellow brown brown red black orange brown brown black black orange brown brown black black red brown yellow violet black brown brown orange white black brown brown red red black brown brown brown black black brown brown yellow violet black black brown orange white black black brown brown grey black black brown not applicable set out to produce a simple, effective yet easy to build exhaust gas monitor. The end result is a unit housed in a small plastic case and using a solid state TGS 812 gas sensor made by Figaro of Japan. The TGS 812 gas sensor is a semiconductor device based on sintered tin oxide (SnO 2). When combustible or reducing gases are absorbed on the semiconductor surface, its resistance is markedly reduced. When the gas dissipates, the resistance returns to normal. Examples of combustible gases are hydrocarbon vapours (from petrol, methylated spirits etc), natural gas, methane, hydrogen and so on. And the prime example of a reducing gas is carbon monoxide. It is also combustible and burns with a clear blue flame. The TGS sensor is housed in a 17mm diameter case with 6 pins protruding through the base. At the top it has an opening 10mm in diameter which is covered by two layers of very fine mesh. There is also a small hole on the underside, again covered with mesh, so that gases can pass through the unit. Inside is a heater element and the semiconductor element. The heater consumes about 600 milliwatts and is there to purge the semiconductor element of gases which are absorbed onto its surface. The double layer of wire mesh is there to prevent the risk of explosion when the sensor is exposed to dangerous concentrations of gas. The circuit Now let us have a look at the circuit (Fig.1). Besides the TGS 812 gas sensor, it uses a quad op amp (ICl), a 3-terminal regulator, two small transistors, a piezoelectric siren and a few other parts. The 7805 3-terminal regulator provides a constant + 5V to the circuit from a nominal 12V supply such as a car battery. The + 5V feeds the heater circuit (pins 2 and 5) of the TGS 812 as well as the rest of the circuit, except for the piezo The three electrolytic capacitors are mounted horizontally on the PCB so that they clear the front panel. Note that the TGS 812 must be installed so that the top of the sensor is level with the piezo alarm. siren which is powered from the + 12V supply. Basically what happens is that the circuit monitors the resistance of the TGS 812 sensor, between pins 1,3 (joined together) and pins 4,6. When the resistance drops, the circuit sounds an alarm. Op amp ICla is the core of the circuit; it monitors the resistance of the TGS 812. The TGS 812 is connected in series with a l0k0 resistor to form a voltage divider across the + 5V supply. The voltage at the centre point of this divider is monitored via a 4.7k0 resistor at pin 5 of ICla. This voltage is compared with a reference voltage set by VR_l at pin 6. Normally, the resistance of the TGS sensor is high and so the voltage at pin 5 of ICla will be low. This means that the output of ICla will be low. When carbon monoxide or .other relevant gas comes in contact with the TGS sensor, its resistance goes low and so the voltage at pin 5 of ICla goes high. This causes the output of ICla to go high and this allows oscillator stage ICld to run. It oscillate~ at about lHz and turns PARTS LIST 1 1 1 4 8 2 2 4 2 plastic utility box with plastic lid, 130 x 45 x 68mm, Dick Smith Electronics Cat. H-2851 or equivalent front panel label (optional) PC board , code SC05107891, 106 x 57mm piezo alarm , 32mm diameter, with inbuilt 3 .6kHz oscillator (Dick Smith Electronics Cat. L-7022 or equivalent) cigarette lighter plug 3-metre length of light duty twin flex with coloured trace miniature SPST switch 1 0mm tapped spacers 3mm machine screws, 6mm long 3mm machine screws, 12mm long 3mm nuts 3mm washers PC pins Semi conductors 1 TGS 81 2 gas sensor (Figaro) Q2 on and off once every second to drive the piezo alarm. This alarm is loud enough to be effective but is 1 LM324 quad op amp (IC1) 1 7805 5V 3-terminal regulator 2 BC548 NPN transistors (01, 02) 15V 1 W zener diode (ZD1) 5mm red light emitting diode (LED 1) 5mm green light emitting diode (LED 2) Capacitors 1 1OOµF 16VW PC electrolytic 1 1 OOµF 3VW tantalum or 1 6VW low leakage electrolytic 1 1OµF 1 6VW PC electrolytic 3 0 .1µF monolithic ceramics Res istors (¼W, 5%) 1 4.7MO 1 2.2k0 2 120k0 2 1 kO 3 100k0 1 4700 2 10k0 1 3900 1 4.7k0 1 1800 1 3 .9k0 1 5 .60, ½W 1 20k0 trimpot (vertical adjust) not so loud as to be painful. Since the base current for Q2 flows through LED 1, there is also a JULY 1989 17 The PCB is secured to the case lid using machine screws, washers and tapped 12mm spacers. Note how the 3-terminal regulator is installed. visual indication of the alarm. IClb and IClc provide a 2-minute muting period for the alarm when it is first turned on. This is necessary because when first turned on the TGS sensor will be "poisoned" by gases which have been absorbed on its surface while it has been in the unpowered state. Its resistance is therefore initially quite low but within two minutes the heater will purge the device and its resistance will go high. IClb can be regarded as an RC timer with a very large capacitance connected to pin 2 (ignore IClc for the moment). When power is first applied, the large capacitance will have zero charge and so the voltage at pin 2 will be zero. This causes the voltage at pin 1 to be high and turn on Ql. This pulls the voltage at pin 5 low and stops IC1a from performing its normal monito'r ing function. The capacitance referred to above then charges via the associated lOkO resistor and the voltage at pin 2 rises. After about two minutes, the voltage at pin 2 will exceed that at pin 3 and the voltage at pin 1 will go low. This turns Ql off and then ICla can function as normal. Capacitance multiplier IClc provides the large capacitance referred to earlier. Obtaining a predictable time delay of more than a minute or so where the physical size of the capacitor is limited can be a problem due to the 18 SILICON CHIP By wiring the power leads to a cigarette lighter plug, you can easily move the unit from vehicle to vehicle. input bias current needed by the op amp and the leakage current in the capacitor. Solving this problem took some ingenuity: we had a spare op amp in the package and so we decided to use a capacitance multiplier. It works as follows: IClc is connected as a "voltage follower" by virtue of the 120k0 resistor between pins 13 and 14. This means that any voltage appearing at its pin 12 will be reproduced exactly at its output, pin 14. Now consider what happens when we first apply power to IClc. The lO0µF capacitor will initially have no voltage across it so the voltage at pin 12 will be zero. Hence, the voltage at pin 14 will also be zero. The lOOµF capacitor at pin 12 now starts to charge up via the associated 120k0 resistor. As the voltage at pin 12 starts to rise, the voltage at pin 14 increases by exactly the same amount. What this means is that the voltage drop across the 120k0 resistor is exactly the same as the voltage across the lkO output resistor and this, in turn, means that the current flowing in the lkO resistor will be 120 times larger than the current flowing via the 120k0 resistor into the lO0µF capacitor. Therefore, as far as the external circuit is concerned, the junction of the lkO and 120k0 resistors behaves like a capacitor which is 120 times as large as the lO0µF capacitor connected to pin 12. Ingenious, eh? This effective capacitance of 12,000µF combines with the 10k0 resistor at pin 2 of ICl b to provide an initial turn on delay of 2 minutes. Power for the circuit comes from the vehicle's 12V battery and feeds via a 5.60 resistor to the input of the 7805 3-terminal regulator. A 15V 1W zener diode provides protection against reverse polarity connection or spike voltages superimposed on the battery line. On the output side of the regulator, a green LED in series with a 3900 resistor gives an indication· that the unit is turned on. Construction The Exhaust Monitor is housed in a standard plastic utility box with a plastic lid. It measures 45 x 68 x 130mm (Dick Smith Cat. H-2851 or equivalent). All the circuit components are fitted onto a printed circuit board (PCB) measuring 57 x 106mm and coded SC05107891. This board is mounted onto the lid of the case so that the TGS gas sensor and piezo alarm protrude slightly from the front panel. The first step in construction is to carefully examine the PCB for any faults in etching; eg, shorts between tracks or pads and open circuits (breaks) in tracks. This done, insert two PC pins for the + 12V and OV supply connections. Now insert and solder the resistors and the three O. lµF monolithic capacitors. The latter will most likely be blue in colour and labelled '104' according to the EIA code. The three electrolytic capacitors are mounted so that they can be Problems? ... and you don't have our .120page catalogue . . . "' N <at> -$- ♦ 26.5 12.5 10 0 13 46.75 46.75 DIMENSIONS IN MILLIMETRES ~ HOLES : A : B: C: 0: 32.5 DIA. 17.5 DIA. 5 DIA. 3.5 DIA. Fig.3: dr~ng temp!ate for the case lid. Holes are required for the alarm, sensor, trimpot adJustment and board mounting screws. laid over on their sides. You can Checking, checking then install the LM324 IC, the 20k0 Now check your work thoroughtrimpot and the two transistors. ly. Are all components where they Make sure that these components should be and cross-checked to are correctly polarised before you agree with the circuit? They are'? solder them into place. Good. If not, fix 'em. The 7805 3-terminal regulator is Now connect up a length of mounted on the copper side of the polarised twin flex and connect a board so that air can circulate 12V supply. If the 5.60 resistor around it. Poke its leads through the starts smoking, you've connected board holes so that they protrude the supply around the wrong way. about 6mm on the component side. The alarm should beep briefly Solder the leads so that the 7805 is when power is applied and then vertical, as shown in the photo. nothing should happen for about Now mount the piezo alarm on two minutes. the board. It is secured with two Now rotate the trimpot clockwise 3mm x 12mm-long machine scre~s until the alarm turns on. It should and nuts and then its leads are beep on and off continuously at soldered to the board. Note that the about once per second. If it does leads are polarised: red for rotate the trimpot anticlockwise un~ positive, black for negative. · til the alarm turns off. Now use That done, the TGS 812 can be your multimeter to set the trimpot soldered into circuit. Its leads are for a reading of + 2V between pin 6 arranged so that it can go into cirof ICl and OV. This is most convecuit either way around but polarity niently measured at the trimpot is not important. Its leads should be wiper (ie, the centre terminal) and soldered so that the top of the senthe PC pin connection for OV. sor is level with the top of the piezo This setting is purely arbitrary alarm. The two LEDs should be mounted by the way and one which we found so that they stand just slightly gives reasonable sensitivity without higher than the top of the piezo · nuisance triggering of the alarm. If alarm. Watch the polarity of the you want the alarm to be more senLEDs - their longer lead is positive sitive, rotate the trimpot clockwise. You can test the Monitor by blow(ie, the anode). At last . . . a TRADE catalogue for the consumer ARISTA .. . your one-stop problem solver. Video plugs and sockets ... Video extension speakers .. . Video flyleads . .. Video RF interference filters .. . Video splitters .. . Indoor antennas . .. Video switching units . . . Down converters . . . Video speaker controllers . .. Video camera lights . .. Video tape rewinders ... Video cine adaptors .. . Video head cleaners . . . Video splicing kits . . . Video storage cases ... Video dust covers .. . Video leads ... Scart plug leads . .. Video dubbing kits ... Video headphones .. . Video shotgun and wireless microphone systems .. . Pre-amplifiers with video inputs .. . Video camera stands .. . Just about anything you want. ... Try us .. . NOW! Get your catalogue FREE from your local ARISTA dealer or send $2.50 P&H and your return address to: ARIST~ ELECTRONICS PTY LTD PO BOX 191, LIDCOMBE, NSW 2141 JULY 1989 19 from the PC pins and the switch wired up as shown in the wiring diagram (Fig.2). Put a knot in the twin flex as a strain relief where it enters through the hole in the end of the case. Finally, secure the board assembly to the lid with four 3mm machine screws. Connecting it up Fig.4: here is a full size artwork for the PC board. ing cigarette smoke into the sensor. It will immediately sound off, proving that you are poisoning yourself. Yes, cigarette smoke contains carbon monoxide, apart from other toxins. If you don't smoke, you can test the Monitor by letting it sniff the cap off a bottle of methylated spirits. This completes the board assembly and checking. It remains for it to be assembled into case. Case assembly Before the PCB can be mounted, the lid of the case must be drilled. Fig.3 is a drilling template, showing the holes for the alarm, sensor, trimpot adjustment and board mounting screws. We also drilled three 6mm diameter holes in each side of the case to allow ventilation of the sensor and the 7805 regulator. Additional holes must also be drilled for the SPST switch and for the supply leads (twin flex). Two holes should also be drilled in the base of the case to allow it to be mounted permanently, if desired. Now affix the adhesive front panel, if one has been supplied. We assume that kits of this project will come with the case ready punched and screen-printed, by the way. In the first instance, kits of this project will be available from Dick Smith Electronics. With all holes drilled in the lid of the case, the printed board can be mounted. Fit a tapped spacer at each corner of the board, with a washer under each spacer. The twin flex should then be removed You have two options for connecting the Exhaust Monitor in your vehicle. First, you can use a cigarette lighter plug (DSE Cat. P-1675 , Jaycar Cat. PP-2000 or Altronics Cat. P-0160). This allows you to move the unit from vehicle to vehicle. Second, you can wire the unit to the + 12V accessory supply at the vehicle's fuse panel. This way, the Monitor will be powered up only when the ignition is on. On other gases To conclude, we must make one final point. The Exhaust Monitor is sensitive to gases other than those occurring in exhaust. The one that comes particularly to mind is methane. That means that if you or one of your passengers suffers from flatulence the alarm will sound. Footnote: while the exhaust monitor will detect petrol fumes, it is not suitable for use on boats in its present form as salt water can damage the sensor. We hope to present a version for boats in a future issue. l§;l EXHAUST MONITOR ALARM ADJUST SENSITIVITY POWER Fig.4: use this artwork to make your own front panel label. 20 SILICON CHIP R. F. DEVICES PTY. LTD. SPECIALISTS IN INSTRUMENTATION & CALIBRATION "WHERE SERVICE IS NOT JUST SERVING" 20 MHz DUAL TRACE OSCILLOSCOPE QUALITY MUL TIMETERS AT AFFORDABLE PRICES KT-8801 • • • • LARGE LCD DISPLAY LOGIC TEST CAPACITANCE TEST TRANSISTOR TEST • COUNTER • INCLUDES SOFT CASE $115.41 $8 70.00 - INCLUDING: KT-8105 • COMPONENT TESTER • PROBES & ACCESSORIES • SALES TAX • • • • • • • OTHER BANDWIDTHS (15,35MHz) etc. AVAILABLE. ENQU IRE NOW 4½ DIGITS 0 OHM ADJUSTMENT CAPACITANCE TEST TRANSISTOR TEST QU ARTZ CLOCK HIGH ACCURACY INCLUDES SOFT CASE $181.00 KT-8205 • • • • • • • ELDITEST SERIES 1000 MODULAR TEST PROBES • • • • UNIQUE "PLUG IN" MODULAR DESIG N ALL PARTS AVAILABLE SEPARATELY WEST GERMAN QUALITY & PREC ISION ALL ACCESSORIES INCLUDED Type Part No. Atten uation ETS 1001 ETS 1002 ETS 1003 90001 90002 90003 1X 1X 1X ETS 1011 ETS 101 2 ETS 10 13 900 11 90 012 90013 10 X 10 X 10 X 90 111 90112 9011 3 1 X / 10 X 1 X / 10 X 1x/10x C (pF) Ba ndwidth (MHz) Risetime (nsec) Cablelength (m) PRICE $ same as Scope 45 70 100 20 15 10 15 20 30 1.2 2.0 3.0 10 10 10 15.0 16,5 19,5 100 80 60 3.0 4.0 5.0 1.2 2.0 3.0 48.24 61.20 67.68 57.48 81.72 89.28 1.2 2.0 3.0 55.80 105.48 114.12 1x ETS 1111 ETS 1112 ETS 1113 $184.00 Input Impedance R (MQ) 4½ DIGITS 0 OHM ADJUSTMENT TRANSISTOR TEST COUNTER QUARTZ CLOCK HIGH ACCURACY INCLUDES SOFT CASE 10 same 10 as 10 Scope 10 R. F. DEVICES PTY. LTD. SUITE 1A, 9 LYN PARADE, LURNEA, NSW 2170. X 1X 55 75 100 10 X 16 18 20 1X 10 15 10 5 100 80 60 X TOLL FREE: (008) 02 367 4 TELEPHONE: (D2) 607 8811 FACSIMILE: (02) 6D7 37 63 TELEX: 127948 1x 10 35 50 70 3 5 7 X * ALL PRICES INCLUDE SALES TAX. * QUALITY ENQUIRE ABOUT OTHER ·TEST EQUIPMENT. * DISTRIBUTORS REQUIRED IN OTHER STATES. SUBJECT TO CHANGE WITHOUT NOTICE. VISA Diners Club /memational' 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. RLY1 Tone decoder input control circuit This tone decoder control circuit was designed for inclusion in a CTCSS radio repeater system. It overcomes the problem of one tone being interrupted by another tone. The circuit uses three lowfrequency tone decoders, each centred on a different frequency. The Rx tone input is connected to the output of a discriminator in an FM receiver. When one of the decoders receives its correct tone, its output switches from logic low to logic high, and then low again when the tone disappears. With no tone input, the outputs of all the decoders are low. This means that the inputs of the three XNOR gates (ICla, IClb & IClc) are also low and so their outputs are all high. Thus, Ql, Q2 and Q3 are all off and relay contacts RLYl, RLY2 and RL Y3 are all closed. Now let's assume that a correct tone is received by tone decoder B. When this happens, its output goes high and this high is directly applied to the pin 6 input of ICl b. Dl, D2 and D3 form a diode OR gate which is driven by the tone decoder outputs. Thus, the high from decoder B is also applied via D2 to Centre-zero meters in power supplies Many readers will have a centre-zero moving coil meter in their junkbox. That's usually where such meters remain because their uses are generally quite limited. One novel application is to use a centre reading meter in place of a conventional meter in power supply circuits. Fig.1 shows how the meter is wired to read volts and amps using just the top half of the scale. As can be seen, a 22 SILICON CHIP 01 1N4148 TONE DECODER A +12V 04 1N4148 10k RLY2 RX TONE INPUT 02 1N4148 ":' TONE DECODER B pins 1, 5 & 8 of ICl. As a result, the output of ICl b remains high and so the RL Y2 contacts remain closed. At the same time, the outputs of ICla and IC1c switch low. This turns on Ql and Q3 and opens relay contacts RLYl and RLY3. RLY1 and RLY2 remain on for as long as the correct tone is received by decoder B. This means that no tone can be received by decoders A and C during this time and thus no interruptions can occur. Peter Howarth, Narrabri, NSW. ($20) +~--------------0+ SHUNT SHUNT INPUT VOLTS +o--~---1,w,,,-.....-o+ OUTPUT OUTPUT VOLTS MULTIPLIER Fig. 1 double-pole switch is required to ensure that the meter always reads with the correct polarity. Alternatively, Fig.2 shows how the meter can be wired to read volts on one half of the scale and amps on the other half. In this MULTIPLIER Fig. 2 case, only a single pole switch is required. The meter scale can be re-calibrated by carefully removing the existing scale plate and attaching new artwork. David Allen, Findon, SA. ($15) Low cost locker alarm +4.BV If a thief tries to raid your locker, this locker alarm circuit will broadcast a signal to a portable FM receiver. It is activated by a microswitch (S1) which closes and supplies power to the circuit when the locker door is opened. The circuit uses just two active devices: a 4011 quad 2-input NAND gate (ICl) and a BC547 transistor (Ql). ICl functions as a lkHz audio oscillator with its frequency set by the 68kQ resistor and .00lµF capacitor. Note that this oscillator uses two paralleled NAND gate pairs. This has been done to use up all the NAND gates in the chip. The output of the oscillator is applied to the base of transistor Ql via a .022µF capacitor. Ql and its associated components function as an FM transmitter S1 + T 14 4.BV I I ...I.. :,!L1 6T, 25SWG ECW .,. .001 stage. L1 and its parallel 47pF capacitor form a tuned collector load for Ql while the 5.6pF feedback capacitor between collector and emitter ensures that the stage oscillates. Drive to the antenna is taken directly from Ql 's collector. For maximum range, the antenna should be about 1.5 metres long. The circuit layout is not critical but keep all leads around the transmitter fairly short. L1 is an HI-PERFORMANCE PASSIVE LOOP TECHNILOOP PX 1 (SEE SILICON CHIP JUNE '89) BUILT U $69 P& air-cored choke. You can make 11 by winding 6 turns of 25 SWG enamelled copper wire (ECW) onto a 3mm former (eg, a drill bit). The circuit can be tuned to any frequency in the 88-lOBMHz FM broadcast band by squeezing or expanding the coil. Power is derived from four AA-size nicad cells. Paul Daniels, Townsville, Qld. ($15) WORLD TUNER AT 4SW A NEW HIGH PERFORMANCE PORTABLE SHORT WAVE ANTENNA TELESCOPIC ELEMENT EXTENDS TO 1.2m. UNSCREWS FOR PORT ABILITY. MEDIUM WAVE TUNEABLE 530-1 650 kHz FOR AMAZING LONG DISTANCE RECEPTION THE PX1 IS NOW USED IN MANY REMOTE PARTS OF AUSTRALIA. HELPS REDUCE NOISE IN BAD LOCA T/ONS. IDEAL FOR AM STEREO. 3mm DIA . a, ,ri i I REALLY PULLS IN THE WEAK ~iv STATIONS! KIT $49.00 BUILT & TESTED CAN BE INDUCTIVELY COUPLED BY STANDING NEXT TO PORTABLES OR CONNECTED BY SUPPLIED CABLE TO TUNERS, ETC. 54 Calder Hwy, Keilor, Vic 3036. l:lI Phone (03) 336 7840. <at> )·., ... :..:......... ::•...:.:,:,........ :..:..:. ;,:.:......:.= :=•...:. ::::,::·.: . :=:=:,::: ~:: $79.00 CARRYING OOE $12.50 P & P $6.50 SOLID STEEL BASE FOR STABILITY. PLEASE NOTE WE ARE A MAIL ORDER BUSINESS. YOU ARE WELCOME TO CALL IN, BUT PLEASE TELEPHONE FIRST. QUALITY KITS THAT PERFORM AND LOOK PROFESSIONAL. PAYMENT BY CHEQUE, MO OR BANKCARDIMASTERCARD JULY 1989 23 7Ue"~ ~ eo9~ , ' " 4 ~ ~ .e ~ ol- ~ e4a ~ - A-ut ~ ~ I 'iD~~ ~•u HUik e4e, ~ ~ d , da:e, ~ k44.. '°°' Pin Point ULTRASONIC CLEANER GUARD YOUR HOME! NEW! NEW! NEW! WIii even clean your teeth! " !. 0 = HOUSE GUARD ALARM SYSTEM (SeeBA~l,/Ap<il'89) Burglaries~ on the incrcuc! Doesn't it make aicn-= topromctyour home and ia contents? ------... This cuy-to-build kit a-,,blcs OIi a single PC and INCLUDES 12V l .2AH inbuilt lesd calcium baclc-up batmry. Feature& Include:• En!Jy mdexit delay• Panic alarm input e Bat1eryback-upe Line monitoring e Softalannrurt e Lamp tell tale output• Auxilliary ,clay for external si=l etc.• Key switch operation• Uses almoot any type of sensor. "Screecher Siren" S 5170 11odb sPL "tJ :c K 1910 Kit less Siren 0 z m $89.00 0 $17.95 ::r, C MULTI SECTOR BURGLAR en ALARM -z 0 Protect your Home CM" Buslneu from Intruder, with this "Slate orlhe Art" Bw-glar Alarm Sy,tem 0 Ovcrthclut few )ean, Houac Break-Im have inaeatcd dramatically. The i,:covery rate of 110len goods is very low. Now more than ever befOIC, it maka oxm:mely good IIClllC to build and install this ingenious MultiSector System. This unique Alarm Systcm incorpora1"1 a: ~ <C Cuts any shape cut out in steel.aluminium or plastic. Very easy to use. Capacity steel 1mm Aluminium 1.6mm T 2355 $19.95 (3) for $180 ::r, Earns its cost bundcrds oftimc1 C/1/cr in cleaning cmncctc:n. PCB 1, 1witcheo,jewellery, gluses, watdic•, drafting pens, etc. 0 Awarded the Good Product Design Award for CElDC in 1987 Woo 't scratch or damage • ,_. ordinary tap wall:T and ci,:at,:s milliOllll of 111per•pcnetrating bubble,. HOIJ>ital tcltl show that Ultruonic clean in& produces be- i,:su!IJ 1afcr than conventional methods. the fea!UIC1 ofthe moie expenaive canmorcial modol1 • at a fraction of the price. Features:(See EA Jan/Feb'IS or our 1989 Catal01ue ror rull reatures) K 1900 Back Up Battery 12V 1.2AHS $149.50 $24.95 5065 Puloe Count Type Our 1989 Model IAD now includes pulse count circuitry with a specific time delay between pulse sensing . Three pulses of IA radiation are required to trigger the detector. Featureo: Lens - wide angle & narrow angle • 12V DC Flowered. A 0100 TOP VALUE AT $199.00 Absolutely ear splitting SPL 120db.Handy Bracket for wall mounting etc. 12V 300mA. s 5177 $24.50 STUDIO 200 SERIES STEREO For the purists Microprocessor Controlled Detector Cllp1 On To SunvlIor lnvlalble from out1lde your vehicle • Thll fanta1tlc high lpec Radar Detector detect, X and K Band Radar up to an Amazing 13KM. MICRO EYE VECTOR Stereo Control Unit (See Sil icon Oiip Jw,e/July '88) Outl'erfonmcommercial uniucosting$600.00ondmon,) Companion to the Studio 200 Sll:m> Power Amplifier and with specifications that match, (See our 1989 Catalogue poge 13) and ii just u straight forward to build. (SeeSCFcb'88) Sensational Specifications! (See our 1989 Catalogue page 13) Yet it will only tala, the average constructor 6 boun to build. Tiu •ill r..U, i,,,p,..,, :,our/ruw/ Great Features: • In-built speaker protection • Low bum toroidal transformer • Pl<>fessional looking. black satin fuulh • Low leakage power supply capacitora • Rugged, custom built chanis K 5010 TOP VALUE AT $399 r r High Energey Siren With Swivel Bracket Detector 100W per Channel Power Amplifier -4 0 In Just 3 minutes you wUI be amued al the dllferenc:el Kit (Leu Battery Back Up) s 5301 Infra Red Movement $79 m t,AULTI SECTORt,A BURGLAR ALAR Controls include: m:blc, ban, balance, tape monitor switch, stereo mono ■ witch and volume control. Inputs IC!ectab!e &om: phooo, tuner, VCR and lape loop. K501s SUPERIOR VALUE AT $229.00 NORMALLY THESE TWO UNITS ARE EXCELLENT VALUE AT A TOT AL OF $628.00 NOW, FOR A SHORT TIME ONLY, WE ARE OFFERING THEM BOTH FOR $550.00. YOU SA VE $78.00 The FlrIt Detector with GaAI DlodeI Until now, GaAs diodes have only been used in sophisticated military radar equipme,,t. The Microeye Vector is the first consumer electronics product equipped with this new technology. Why GaA1 Dtode1 Make The Difference • Lower threshold allows for a better signal to noise ratio • Lower signal conversion loss• Higher barrier reduces noise. Quite simply, GaAs diodes increase the sensitivity of the microeye Vector. • Simply plugs into your cigarette lighter socket or can be direct wired into your existing car wiring• CllpI onto 1unvl1or. • Detects Mobile Radar Equipment • Highway/ City/Modes • Separate audio alerts for X and K Band • Visor bracket • Velcro • Cigarette Lighter Plug. A 1530 Normally $499 Save $100 this Month $399 PHONEORDER TOLL FREE ALTRONICS 008 999 007 0 0 0) CD CD CD 0 0 ....... PHONEORDER TOLL FREE ALTRONICS 008 999 007 Ultra High Power Capacity Polypropylene Bass Drivers Our ALL NEW "Blaclt" polyprop cone Bass Drivers exhibit quite astonishing low register reproduction. Power ratings quoted are conservative. Not the cheapest but deflnltely the BEST VALUE we know of- ANYWHERE. C3070 1O" WOOFER ,, 60Watt RMS 100W Max. C3065 Normally $99 Was$69.00 12" (300mm) WOOFER 100Watt RMS 150W Max. NOWONLY$89 Ideal for "live" recording, our NEW Audio Mixing Console has truly sophistic&te<I features: NOW ONLY $49.00 PROFESSIONAL STEREO CONSOLE MIXER • PA mixing • Fantastic tape recording et Stereo/mono VCR recording • AIL 5 band graphic equalisers • Talkover facility • Separate headphone level control • Patch switch bank • Individual controls for Microphone, Phono 1&2, Aux. line 1&2, and Master slide level controls. Bleryl up to two magnetic or crystal tumtablea, two tape deck ■ and two mlcrophonea - all at once II FULLY PROFESSIONAL SPECS: . Input - Mic 1: 0.SmV, 600 Ohms, Mic 2: 0.SmV, 600 Ohms (Low imp.), 2.SmV, 10kOhma (low k'np.); Phono 1&2 (Mag.) 3mV, 50k0hms; Phono 1&2 (Cry.), 150mV, 100k0hms; Tape/'Tooe, 1&2 150mV, 100k0hma · Equall•r - 5 ~oquency bands: 60Hz, 250Hz, 1kHz, 4kHz, 12kHz - Boost Cut Ral,go, plus o, minus 12db O $4 99 .OO PHONEORDER TOLL FREE ALTRONICS 008 999 007 PHONEORDER TOLL FREE ALTRONICS 008 999 007 MOTOROLA DATA MANUALS SOLDERING SPECIALS IN '89 De-Solder _Iron SPECIAL $49.95 DIL SWITCHES Gold plated Hlf-wtplng contacts ~--..-~·-• ,-~ . ~. ·· ', ' ' Ideal for the senice uchnician and hobbyist alike. Allows co,nponents to be quickly and cleanly rtmoved wilh one hand. Comes with a cleaning wand. ~ OLD PRICE cad, 240V AC SOHz 30WISEC Approval W/22281Euy single handed actioo!Simpc cleaning action. NEW FOR '89 ,..._ 0 0 0) 0) 0) (X) 0 0 en -z 0 0 a: !::i c( w w a: Electronic Temperature Controlled Temperature Selectable, Soldering Station Linear and Interface Data Includes Data design procedures and equivalent listings for 1000's of devices under headings Op Amps. Voltage Regulators, Consumer Circuits (e.g .TV Automotive power) High Frequency Circuits and Special Purpose circuits. B 1114 $29.95 Motorola 8 Bit Microprocessors and Peripherals Now this is reallr quality and versatility! This manual covers all aspects of Motorola's microprocessor, microcomputer and peripheral components. A clearly wirtten manual providing all the data necessary to design and build a working computer system from scratch 100's of circuit examples, flow charts, truth tables and programme routines. B 1125 $28.00 320'C(608°F) 350-C:(662"1') 380-C:(716-F) 410-C:(770-F) 440-C:(824'1') withoot clwtging heater or tip. Save $20.00 Now! THIS MONTH ONLY $119.95 C $1.80 $1.95 $2.25 $2.SO $2.90 sue SU5 UTILITY PARTS CASE "'C :::c 0 z m Featuring a clear plastic lid so you can 1"11 conb:nta at a glana:. Simple slide lock. 48 partition combinations. Very sturdy ABS Jllaltic, $23.95 NOW ONLY $18.00 SPECIAL D SERIES CoMPUTER CoNNECTORS • GoLD PLATED Packed with features: • Tcmpcratur,: readout• Tcmpcralllft: con1ro1 e Zero voltage switching e Ground tip e Low voltage clement e Cbrcme plated. iron clad tip Professional Series t---- ---------~- ------------- • 300 Watt Inverter with Auto Start Ccmplete Kit K 6750 $279.00 Fully built and b:sted K 6755 $379.00 0B9 HUGE SAVINGS ON Professional Quality W or Security ~ Keyboard :C Switch Matrix c. Type $5.00 $4.50 P P P P P P P NORMALLY 3000 Male 9 Pin 3010 Female 9 Pin 3020 Male PCB Rt/L 3030 Female PCB Rt/L 3040Male PCB Mnt 3050Female PCB Mnt 3()1)0 Bacubell cover Value at Be Quick 1 - 49 $1.50 80CI: ea 70CI: ea P 3100Malc lSPin P 3110Fcmalc 15 Pin P 3120Malc PCB Rt/L P3130FcmalcPCBRt/L P 3140 Malo PCB Mnt P 3150 Female PCB Mnt P 3190 Bacuhellcowr ea ea Heat Sink Bargain 50 or More .,,:tJ THIS MONTH $2.95 $3.25 $3,75 $4.SO $2.95 $3.95 $1.95 $!.SO $!.SO $3.00 $3.00 $2.00 $2.SO $1.00 $3.25 $3,85 $4,35 $5.SO $3,85 $4.85 $2.20 $!.SO $1.90 $2.95 $2.00 $2.00 $2.95 $1,00 $4.95 SS.SO $4.95 $6.90 $4.95 $6.25 $2.SO $1.95 $2.20 $3.SO $4.SO $3.SO $4.SO $ 1.00 -en0z 0 0 0:, (0 (0 (0 0B15 Thermalloy T03 H 0503 arr 0 s., .. r 1989 C""'/op• 1'4• 10 for f•U delGila S 5380 NOW 10 Plus :tJ !:i :tJ Powerhouse 600W lnl(erter 0 1:T;e:;l=ep~h::o::n::e7""9iiiiii C m )> Many combination• to choose from: (Sec EA Dec'87l Kit vcraioo K 6770 $425.00 Fully built and tested 12V Input K 6774 $525.00 24V Input K 6775 $525.00 0 :tJ m m INVERTERS Depending on power capacity thc,c models will power: Miaowavc OYCDS, 'IV 1eta, Hi Pi, AC lighting., Electric drill and 1 OO's of other appliances to make your liti: easier. Ideal fo, camping. farming. mining, boating,• anywhere out of reach of the oldcxtemioocord, a: 2Way 4Way 6Way sway 19Way T 2440 Normally $139.95 ..J ..J w S 3045 S3050 S 3055 S3060 S3065 H02411WAS The MICRON 1'2440 soldering mtioo offi:rt the ultimate in controlled tempcralllft:, hand soldering. Simply rotalc detained rotary switch freely to ,electable fixed tempcralur<:• of: Get 240V AC Mains Power from your battery with these handy Inverter kit sets a: Normally $59.95 SOLDERING STATION MICRON T2440 LL ~ T 12so NEW PRICE oadi $1.00 $1.20 $1.78 LABTECH - 1GHz FREQUENCY COUNTER ......... E111r,,,.,1, /tig/t «<<•""1 u4 d41bililJ-u 1/tia '""' iium,,,..,., i,u,,/ for llu ,.._,,,,, worbltop, 111ainr6ily or teclanical colkge. e 8 digit, 7mm, red Um display with decimal point, pte, overflow, kHz, MHz and uS indicatioo. • Many ranges for fff:qucncy, ff:aolutionand gate time • High aCCW11.cy and ,tability on all scales and ranges • See our 1989 Catal011uo for the very Impressive specllk:.allons. run a 1530 Was $499.00 Now only $425.00 SA VE over $70.00 0B25 P3200Malc25Pin P3210Fcmalo25Pin P 3220 Male PCB Rt/L P 3230 Female PCB Rt/L P 3240 Male PCB Mnt P 3250 Female PCB Mnt P 3290 Bacuhell cowr MANYAT HALF PRICE OR LESS PHONEORDER TOLL FREE ALTRONICS 008 999 007 0 0 ....., PHONEORDER TOLL FREE ALTRONICS 008 999 007 MEGGER METER MIN MITTER FM STEREO TRANSMITTER :, (See Silicon Chip Oct'88) for insulaticm. breakdown. Now Only llllulaticn 1-akdown can be dcb:mtlnod by the u,e of this dual range mcgolnn mc1Dr. $39.00 Jdcally ■uib:d for cbeclcing 1-akdown in electrical wiring, applianaia TMr•:,o.,CDp,,,,.,iltlo•MiltiFM Simple, educational and fun to build. From the early daya of radio. Uaea only 3 1ranailton but will pick up a larF range of statiom. Uaea Varicaptuning. K 1150 Usually $55.25 l'- 0 0 12/240V INVERTER (SceHAAug'85) K6705 ' •' I O') CX) 0 O oen - Z 0 a: GrMtfor1""'1lGppU.11c ..t Have the comfort and convenience of your hcmc appliances while camping - just power them from your car banmy. Th: pn,cillo, crystal controlled output make,, it ideal for running frequency acmitivc appliance, 1Ucb. u belt drive tumtablet. GREAT VALUE AT ONLY $89.00 U1• u • 1HIJt,ry c#Mrg,r •IIMr 110,,.,,,.l ,-uuconditiou. w 008 999 007 a: portable radio. Powen:d by one 1.!,V penlib: battery. Single JC circuit makc1 it euy to build. measured at either SOOV or 1000V depending a, the Now Only $32.00 SA VE OVER 25% required situatioo. Would H,it ,Nclrieia,u or l•c/e11kNUU wont NII, tool boz or work b•11cA. K5790 $79.95 For Increased Power Two Tube Option K 5795 $16.50 :I: 0 The Ultimate In Vehicle Protection Car Security System m Features: • Auto Arming with exit and entry delays. • Dash Mount status indicator • Remote Protection of bolt-on accessories. • Inc. circuitry to monitor any failure of dash warning lights • Protects your expensive stereo from ~ K 4340 $3 g 5 o •A;~r;,~i~;~~::::•;:~:0R PACK 0 ·• "'tJ REAL VALUE $79.00 K255s Uses Vibration Sensors to guard against · tampering & vandalism Fluhca in time to your mw:ic, or u normal strobe. Exclusively custcmi9c:d by Altronics intoourH 0480 Instrument Cue. Includes ■ ilk , - d pm:I. l-=======~_ ___:_____ ~~~~ [ BANKCARD jj] w ~ :.J <( and altcmatcn etc. Breakdown can be can tun= in with your Walla:nan or K 1120 Normally $43.50 BEAT TRIGGERED STROBE (See AEM Jufy'85) tramf<llDEtl, automotive gcncraton T,.,,_ilt,, Convert ■ CD 1igml to FM 1ignal 10 you • O') O') See HA April/May 89 Checlcaelectric■I wirins and appliancca • z 0 :c C m :c -I Q I I ,, :Il)>m Inc. Mic Cable & Connectors $15.00 1. --1I :C ~ ...J ----------------~-..:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.., ...J 0 z ~ 0 (/) a: 174 Roe St. Perth W.A. 6000 u. K 4341 Manufacturers, Contractors and Bulk Users Please Contact Our Wholesale Sales Dept. Sydney (NSW Only) Colin Fobister (02) 437 4077 Melbc.urne (Vic/Tas Only) Brian Sorensen (03) 811 9967 Perth (W.A., S.A., OLD., N.T.) (09) 328 2199 w PHONE TOLL FREE 008 999 007 Perth Metro & After Hours (09) 328 1599 ALL MAIL ORDERS ·1 E h WA 6000 P. 0 · B OX 8350 Pert h M81 XC ange · · C a: 0 w z 0 :c a. ALTRONICS RESELLERS Chances are there isan Altronics Resellerright near you-check this list or phone us for details of the nearest dealer. Pl ■-1■ Not■: Resellers have to pay the cost of freight and insurance and therefore the prices charged by individual Dealers may vary slightly from this Catalogue - in many cases, however, Dealer prices will still represent a significant cost saving from prices charged by Altronics Competitors. Don't forget our Expr■H Mall and Phone Order Service - tor the coat of ■ local cell, Bankcard, YIN or Maat■rcard hold■rl c■ n phone order for Nm■ day de1i,atch. Blue Ribbon DHl■rl are highlighted with a ■ These Dealers generally carry a comprehensive range of Altronic proc111cts & kits or will order any required item for you. · STAN DARD DELIVERY & PACKING CHARGE $4.00 to 1Kg $7ov■r 1Kg AUSTRALIA WIDE - We process your order the day received and despatch via. Australia Post. Allow approx 7 days from day you post order to whe n you receive goods $7.00 OVERNIGHT JETSERYICE - We process your order the day received and despatch via. Overnight J■to■ rvlc■ Courter for delivery next day Country areas please allow additional 24-48 hours. Weight limit 3Kgs (3Kgs covers 95% of Orders). $10.00 HEAVY HEAVY SERVICE - All orders of 10Kgs or more must travel Express Road - Please allow 7 days for delivery. INSUR AN CE _ As with virtually every other Australia n supplier. we sen_d goods at consignees risk. Should you require comprehensive insurance cover against loss or damage please add 1% to order value (minimum charge $1). When phone ordering please request "Insurance". TOLL FREE PHONE ORDER_ Bankcard.Visa. Mastercard Holders can phone order toll free up to 6 pm Eastern Standard Time. Remember with our Overnight J■to■rvlc■ we deliver next day. C OUNTRY ALBANY BP Electronics ■ 412681 ESPERANCE Esperance Communications 713344 GERALDTON K.B .Electronics & Marine 212176 KALGOORLIE Todays Electronics ■ 212777 KARRATHA Daves Oscitronic 854836 MANDURAH Lan ce Rock Retravision 351246PORT HEADLAND Ivan Tomek Electronics 732531 WYALKATCHEM D & J Pease 811132 NT ALICE SPRINGS Ascom Electronics 521713 Farmer Electronics 522967 AC T CANBERRA Bennett Commercial Electronics 805359 Scientronics 548334 VICTORIA CITY All Electronic Components 6623506 SOUTH MELBOURNE Winscott Trading 6995740 SUBURBAN CHELTENHAM Talking Electronics 5842386 CROYDEN Truscott Electronics ■ 7233860 PRESTON Preston Electron ics 4840191 C OUNTRY BENDIGO KC Johnson ■ 411411 MORWELL Morwell Eleclronics 346133 QUEENSLAND CITY Delsound P/ L 8396155 SUBURBAN CAPALABA David Hall Electronics 3902399 FORTITUDE VALLEY Econ omic Electronics 2523762 WOODRIDGE David Hall Electroni cs 8082777 C OUNTRY CAIRNS Electronic World ■ 518555 BUNDABERG Bob Elkins Electronics 721785 GLADSTONE Supertronics 724321 MACKAY Philtronics ■ 578855 ROCKHAMPTONAccess Electronics (East St.) 221058Xanthos Electronics 278952 TOOWOOMBA Hunts Electronics ■ 329677 TOWNSYILLE Solex ■ 722015 SA CITY Force Electronic ■ 2125505 SUBURBAN BRIGHTON Force Electronics ■ 3770512 CHRISTIES BEACH Force Electron ics ■ 3823366 ENFIELD Force Electronics ■ 3496340 FINDON Force Electronics ■ 3471188 LONSDALE Force Electronics ■ 3260901 COUNTRY MT.GAMBIER South East Electronics 250034 WHYALLA Eyre Electronics ■ 454764 TASMANIA HOBART George Harvey ■ 342233 LAUNCESTON George Harvey ■ 316533 Nichols Radio TV 316171 NSW CITY David Reid Electronics ■ 2671385 CARINGHAH Hicom Unitronics 5247878 COU NTRY COFFS HARBOUR Coifs Habour Electronics 525684GOSFORD tomorrows Electronics 247246 GRAFTON East Coast Electronic 431250 NELSON BAY . Nelson Bay Electronics 813685 NEWCASTLE Novocastrian Elect.Supplies ■ 621358 NOWRA Ewing Electronics ■ 218412 RAYMOND TERRACE Alback Electronics 873419 WINDSOR M & E Electronics 775935 WOLLONGONG Newtek Electronics ■ 271620 Vimcom Electronics 284400 WA PHONEORDER TOLL FREE ALTRONICS 008 999 007 0 0 (X) (0 (0 (0 0 0 ..... VINTAGE RADIO By JOHN HILL Old Henry: one of my favorites This month, I thought I would describe in detail one of my favorite old radio receivers. This nameless console model is of about 1933 vintage, is huge in size and is so ugly that the designer must have been totally inartistic. However, it performs very well for an old timer and is one of my most valued possessions. My nameless set isn't really nameless - I call it Henry. This often prompts a question as to why not Henrietta? My standard reply is that no woman could be so shapeless - it just has to be Henry! Henry is all square corners and sharp edges with short thick legs. One could never think of such a form as "she". There seems little doubt (in my mind anyway) that as far as early radio was concerned, big was beautiful! Henry fits this description fairly well for nearly everything about him is big. But while the cabinet is quite large and the chassis enormous, the dial goes in the opposite direction and is but a tiny circular spot on the front panel. In fact, the dial is greatly out of proportion to the The all-aluminium chassis is an impressive sight to say the least. The aerial, oscillator and IF coils are housed in unpainted aluminium cans while the four valve shields are of polished aluminium. They don't make radios like this anymore. 28 SILICON CHIP overall bulk of the set but that was pretty much the norm for the early 1930s. Another thing that looks out of proportion is the size and spacing of the three control knobs. They are so close together there's hardly room for fingers. It seems so pointless when there is so much room to spread them out. The circuitry On the other hand, from an electronics point of view, Henry was ahead of his time. The circuit is unusual in many respects and differs considerably to what I consider normal. It is these differences I wish to discuss in this particular story. The power transformers and high tension chokes are worthy of note for old Henry has two of each. The larger of the two transformers is mounted on top of the chassis and is a huge affair enclosed in a pressed steel case. This "Clock" brand transformer is strictly for the high tension supply and provides the rectifier valve (an 80) with high voltage for its anodes and 5V for its filaments. After the rectifier, the high tension DC is passed through a 30 Henries (no relation) choke to smooth out the ripple. This choke is in addition to the usual speaker field coil. As might be expected, when both chokes are combined with a couple of electrolytics, there is absolutely no mains hum in the loudspeaker. The rectifier socket is of the old 1920's style and sits on top of the chassis. Its external connections are not only bare but quite accessible to probing fingers. Receiving a The large high tension transformer (right) and the 30 Henry choke are mounted side-by-side at one end of the chassis. The transformer's job is to provide the necessary voltages to the rectifier valve (an 80) for the high tension supply. Henry's cabinet is hardly a thing of great beauty but is pretty much the norm for the early 1930s. The cabinet stands 42 inches (that's over 1 metre) high. The rectifier socket (with bare connections) is mounted on top of the chassis. The small globe connects the transformer centre tap to earth. Bare external terminals with a potential exceeding 300 volts DC protrude from the side of the 30 Henry choke. Don't touch - they can deliver an almighty wallop! high voltage boot from the rectifier socket is as easy as poking a finger onto the hot connections. There are other nasties beside the rectifier socket. The chassis mounted choke is also connected into the circuit with bare external terminals. These terminals are at the rear of the set and are so positioned that 300 volts plus is well within reach if one wished to check the high tension with a finger. One slightly incinerated hand would certainly mean that there's nothing wrong with the HT! While we're on the subject of all these electrical booby traps, I should also mention that one of the power transformer's three primary taps (the one not connected to the mains) was just tied up in a knot with the bare wire protruding. This didn't appeal to me very much so 1 taped it up. The foregoing should be sufficient warning about the hazards of tinkering around with old radios. Some of the early manufacturers made very little effort (none at all really) to insulate dangerous voltages from the user or serviceman as the case may be; Even so, I don't consider the set to be particularly dangerous, but I do treat it with the respect it deserves. I guess it's a bit like playing Russian Roulette, but in this JULY 1989 29 The small dial and the closeness of the controls are out of proportion to the overall bulk of the set but pretty much the norm for the 1930s. In fact, the controls are so close that there's barely enough room for one's fingers. case the player knows which chamber the cartridge is in. That makes the odds a good deal better. The second power transformer is about half the size of the main transformer and is mounted under the chassis. This smaller unit has only one secondary winding of 2.5 volts and naturally supplies the heaters of the other valves. Both the transformers and the chassis mounted choke are particularly large and heavy and are more than adequate for the job. An hour's use will see the 2.5 volt transformer rise in temperature to slightly warm, while the main transformer and the high tension choke remain cold. Parallel pentodes Another unusual aspect of this particular radio is its output stage which consists of two 59 pentodes in parallel. That's right - parallel, not push-pull! These two valves are connected grid to grid, anode to anode etc and work in parallel. Withdrawing either of the output valves has no The output stage uses two 59 power pentodes in parallel for increased audio output. Withdrawing either of the output valves has no affect on the set's operation apart from a slight drop in volume. 30 SILICON CHIP affect on the operation of the receiver apart from a slight drop in volume. The old 2.5 volt 59 is an unusual pentode in that the suppressor grid is lead out to a separate base pin. In any normal pentode the grid is earthed internally through the cathode. Such a set up gives the 59 an additional base connection and also allows it to be referred to as a "triple grid" valve. How the three grids are connected is entirely up to the set's designer. Another different aspect of the 59 is that it has two separate heaters with two separate cathodes. This type of construction is almost exclusive to the 59 valve. Most other AC valves have cylindrical anodes surrounding a single central cathode. I'm quite keen on the 59's odd construction characteristic because a valve with one blown heater will still work reasonably well on the remaining cathode. Henry has one such valve and it tests at 75%. Even with the socalled good valve removed, the set will still function on the remaining 59 with its blown heater. At one stage I was inclined to scrap this half defunct valve, but it can stay in service for a while yet. There is every chance that it will keep on going for years. The other valves are also of the 2.5 volt variety and include the fairly common types of 5 7, 58 and 2A6. The 2A6 is a duo diode triode which will immediately suggest to many readers that the set has AVC (automatic volume control) or, to use the more correct term, AGC (automatic gain control). Henry's AGC is of the delayed type and the delay can be noticed when one crashes onto a particularly strong station. The sound is momentarily louder before the volume adjusts itself. · The set has no tone control but the circuit is such that it produces a particularly mellow sound and there really is little need for an additional tone control. Whilst on the subject of controls, Henry is equipped with an on/off switch which is fairly unusual for a radio of that vintage. The chassis itself with its attach- FIX-A-KIT Kit Repairs - $1 5 per hour. Normal Rate - $35 per hour. No charge for kits that can't be repaired . 3 month Warranty on repairs. Construction - fixed or hourly 1 2 Month Warranty on Manufactured Kits. Custom Designing, Manufacturing, Large or Small Quantitites. Old Henry is truly a gutless wonder. Note the small power transformer on the left. This supplies 2.5V AC for the valve heaters. ed cans and valve shields is also worth a mention because everything is made of aluminium. Both the aerial and oscillator coils and the IF transformers are all housed in unpainted aluminium cans, while the four valve shields are of polished aluminium. Small dial With all this hardware, the chassis is an impressive sight when laid out on the work bench. Unfortunately, the effect is spoilt by the small and somewhat unimpressive dial but I guess that that was the way they made them back in the early 1930s. The miserable looking dial unit drives the biggest 3-gang tuning capacitor I have seen. The tuner has built in mica trimmers on each gang and these are conveniently placed on top for easy access. Henry, like many other vintage radios of the early superhet era, has an intermediate frequency of 175kHz. While this frequency may sound strange by modern standards (455kHz), it was common in Henry's day. Up-ending the chassis is a bit of a struggle due to the weight of the transformer and choke at one end. However, once up-ended, the underneath view is somewhat disappointing. There is so much space for so few components it looks as though someone has left out most of the parts. This, however, is only an illusion for everything that should be there is there, even if it looks a bit to the contrary. The tapped, wirewound voltage dropping resistor and the large size of the one watt carbon resistors are about all one could comment on as far as the under-chassis parts are concerned. It looks pretty untidy really, due to the point-to-point wiring technique employed. Henry is fitted with a 10-inch Jenson electrodynamic loudspeaker and this functions reasonably well for its age. Undoubtedly a more modern speaker would sound a little better but Henry is one set that I want to keep original. The fact of the matter is that the original Jensen speaker really does work OK and produces quite a good sound. In many ways, old Henry is a bit of a strange beast. But as I said earlier, he's one of my favorites. Really, he's quite outstanding in a number of ways. He is the only receiver in my collection with seven valves, the only one with a twin output stage and the only one with an aluminium chassis. Henry is also the largest set I have and possibly the most horrible to look at. But he does perform well and for only $40 I reckon he was a bit of a bargain as well. Perhaps at some other time in the future I will write about another of my favorites, but not many could hold a candle to old Henry. i!tl HYCAL INSTRUMENTS Design, Manufacture, Repair of Electronic Equipment. (02) 633 5897 Unit 4, 62 Great Western Highway, Parramatta, NSW 2150. Trading hours: 8am to 3pm Monday to Friday. D.DAUNER ELECTRONIC COMPONENTS WE STOCK A WIDE RANGE OF ELECTRONIC PARTS • for Development • Repair • Radio Amateur • Industrial Electronic • Analog and Digital WHILE STOCKS LAST * THE FAMOUS TR-DIP METER (as featured May '89) $98 .00 * CRO-VALVE 3ACP2A $45 .00 * PHILIPS IR-IMAGE CONVERTER VALVE XX1080 $45.00 (For use in infrared sight experiment systems) Come and see. Showroom: 51 Georges Crescent, Georges Hall, NSW 2198 (Behind Caltex Service Station In Birdwood Road) Phone 724 6982 TRADING HOURS: Monday to Friday 9.00 a.m. to 4.00 p.m. Saturday from 9.00 a.m. to 12.00 noon. JULY 1989 31 Add extra touch switches to your room An extension for the Touch-Lamp Dimmer If you are building the Touch-Lamp Dimmer described in last month's issue, you can add one or more extension units so that you can dim your lights from several positions. These can be simply wired in place of 2-way switches. By LEO SIMPSON Dimming from one point is OK for small rooms but if you have very large rooms or a hallway you probably want to be able to dim or turn your lights on and off from several points. For example, there may be several entrances into a large room or hallway and it is convenient to have a touchplate near each doorway. Another room where it is convenient to have two touch plates is the bedroom - put one near the doorway and another near the bedhead, so you don't have to get out of bed to turn off or adjust the light. No modifications are needed to the the Touch-Lamp Dimmer in order to add the extensions. It is just a matter of wiring them to the connection terminals on the TouchLamp Dimmer board. The Dimmer extensions are built behind the same standard plastic grid and decorative plate from the HPM Decorator range. In that way the extensions look exactly the same as the Dimmer itself. How it works Fig.1 shows the circuit details. It consists of one PNP transistor, two zener diodes and a few other bits. It is wired between the Active and Extension terminals on the TouchLamp Dimmer. As with the Touch-Lamp Dimmer circuit, the common reference in the extension circuit is the Active line of the mains. The circuit works quite simply. When you touch the Touch Plate, you "pull" the junction of zener diode ZD1 and diode D1 low with respect to the Active line. This causes a 50Hz voltage to be impressed across zener ZD1 and this signal is rectified by D1 to produce several volts DC across the .01µ,F capacitor. This small DC voltage then biases on transistor Qi via the 2.2MO resistor. So Q1 switches on and effectively connects the "Extension" line to the Active line. The two zener diodes are included in the circuit for voltage limiting. ZD1 limits the voltage developed across the .01µ,F capacitor and thus helps define the response time of the circuit. ZD2 limits the voltage across Q1 to a safe value so that there is no danger of transistor failure. Construction The Touch-Lamp Dimmer Extension is built behind the same blank grid as used for the main Dimmer. The PC board is secured to the grid using a 12mm-long raised head screw and two nuts (one either side of the board). 32 SILICON CHIP As mentioned earlier, the TouchLamp Dimmer Extension is built behind a standard HPM blank Decorator grid. We suggest that you use the same grid and decorative plate as for the main Dimmer. .--------------------oA PARTS LIST 250VAC 1 PC board, code SC10107892, 53 x 71mm 1 HPM white Decorator blank grid and gold plate, DR770GF/WE/G 1 2-way insulated terminal block 1 3mm dia. x 12mm-long countersunk raised head machine screw 2 3mm dia. nuts 1 3mm washer ZD1 s,-iv J 3.3M .01 01 BC559 D1 1N4148 B EOc VIEWED FROM BELOW ,___ _ _ _--OEXTENSION TOUCH LAMP DIMMER EXTENSION Semiconductors 1 BC559 PNP transistor (01) 2 6.8V 1 W zener diodes (ZD1 , ZD2) 1 1 N4148 silicon diode (D1) Fig.1: when you touch the Touch Plate, a 50Hz voltage is impressed across ZD1. This signal is rectified by D1 and switches on PNP transistor Ql which effectively connects the Extension line to the Active line. The few components are all mounted on a small printed board measuring 53 x 71mm and coded SC 10107892. The wiring diagram can be seen in Fig.2. Note that the board uses the same Philips VR37 4.7MO high voltage resistors as specified for the Touch-Lamp Dimmer. These must be used otherwise the safety of the circuit may be jeopardised. The assembly procedure is as follows: Step 1: inspect the board careful- Capacitors 1 .01 µF 1 OOVW metallised polyester (greencap) ly for any defects such as shorted or open circuit tracks and correct drilling of the holes. Make sure that the board will fit over the 8 locating lugs on the HPM plastic grid plate. Step 2: insert two PC stakes into the board and solder them. These provide the connection points for the 2-way insulated terminal block. Step 3: install the resistors and the .OlµF capacitor. The colour codes for 4-band (5 % ) and 5-band (1 % ) resistors are listed in the table associated with the wiring diagram Resistors (¼W, 5%) 2 4. ?MO (Philips VR37 high voltage; do not substitute) 1 3.3MO 1 2.2MO 1 2200, 1W of Fig.2. The capacitor may be labelled .OlµF, 10n or 103K. Step 4: install the diodes and Fig,2: it should only take you a few minutes to install all the parts on the PCB. Do not substitute for the two 4.7Mrl resistors specified in the parts list. If they're not Philips VR37 types, don't use them. TOUCH PLATE .-.--=!=4.=7M=l-e-<at>----------, m24~VAC imtJ t.o,o~fi1 ~ 6- ~ EXTENSION METALLISED POLYESTER CAPACITORS ~ZD~ 0 Z 1~ No. □ 0 1 Value .01µF IEC EIA 1 On 103K RESISTORS No. □ □ □ □ 2 Value 4 .7MO 3 .3MO 2 .2MO 2200 1W 4-Band Code yellow violet green yellow* orange orange green gold red red green gold red red brown gold 5-Band Code not applicable orange orange black yellow brown red red black yellow brown not applicable * Note: the two 4 . ?MO 5% tolerance Philips VR37 high voltage resistors do not have a gold tolerance band - it is yellow. If the two 4. ?MO resistors you have been supplied with do not have a light blue body (10mm long) and a yellow tolerance band, you have been supplied with the wrong type. Do no use them! JULY 1989 33 Step 7: electrical check. This is the same test as for the TouchLamp Dimmer. Switch your multimeter to the highest resistance range and measure between the Active terminal and the touch plate screw. The resistance should be infinite in one direction and 15MO in the other (ie, do the measurement once and then reverse the leads to do it again). If you have an analog multimeter, you should get zero or negligible pointer deflection for both measurements. If this measurement is not right, check that you have the right value resistors installed. Installation A small washer or solder lug must be soldered on the copper side of the board for the touch plate screw connection. Check your work carefully before mounting the board on the blank grid. When the board is mounted on the blank grid, the washer on the copper side makes contact with the nut used to secure the touch plate screw. A second nut is then used to secure the board. transistor into circuit. Note that their polarity must be correct. The cathode of all three diodes is shown by the band at one end. Install the diodes as shown and make sure you use the correct type at each location. Step 5: solder a washer or solder lug on the copper side of the board. This is for the touch plate screw connection. Now carefully inspect all your work and soldering before the next step. Are all components correctly positioned and soldered in? Good. 34 SILICON CHIP Step 6: fit the board to the blank grid plate. You will need to drill one 3mm hole in the grid plate for the touch plate screw. Locate the board over the 8 lugs to mark the position of the hole to be drilled. The hole should be countersunk slightly on the dress panel side and fitted with a raised head countersunk 3mm machine screw 12mm long. The screw is secured to the grid plate with one nut. Do it up tight, then fit the board and secure it with a second nut over the screw. Make sure it is tight. If you have an existing 2-way switch for your lights, as shown in Fig.3(a), it is a relatively simple matter to install the Dimmer Extension. Fig.3(b) shows the details. If you want to install the Dimmer Extension in a home where there are presently no 2-way switches, you will need to have a licensed electrician run a 2-way cable from the Touch-Lamp Dimmer board to the proposed extension touch plate location. Note that you can have as many extensions as you like although we doubt whether more than three would ever be needed for one Dimmer installation. One point to be watched is that you must not transpose the wires for the Active and Extension inputs. If you do so you will probably burn out the 2200 1W resistor and possibly do other damage. Cleaning After some period of time, the Dimmer touch plate may collect dust and grime on the polycarbonate grid plate. This can cause false triggering of the dimmer. The cure is easy - just give the grid plate a wipe over with a clean cloth. Troubleshooting Now a few words on troubleshooting the Touch-Lamp Dimmer and extension circuits are appropriate. One thing you can't do is attempt to make any checks on the TouchLamp Dimmer while it is connected MAIN SWITCH REMOTE SWITCH LAMP l - - - < l NEUTRAL ACTIVEO----~- (a) NORMAL TWO-WAY SWITCH TO OTHER EXTENSIONS (OPTIONAL) A ~ ~ --,-p-~-----.....;:i.-Jl.0-~l : C I < ~ } -J w DIMMER EXTENSION 0 ACTIVE ;--+--<at>-o NEUTRAL ~ ~ TOUCH LAMP DIMMER (b) TOUCH-LAMP DIMMER WITH EXTENSION(S) Fig.3: here's how to wire the Dimmer circuits in place of an existing 2-way switch arrangement. Don't transpose the wires for the Active and Extension inputs - you'll burn out the 2200 1W resistor if you do. to the mains wiring. That would be extremely dangerous. However, if your Touch-Lamp Dimmer fails to function as it should, it is possible to rig it up to a low voltage AC supply and ·then check it out in perfect safety. The method is as follows. You need a power supply or transformer which will deliver about 15 to 18 volts AC. You also need a 12V filament lamp, say around 18 to 21 watts, to substitute for the 240V AC lamp. Fig.4 shows how to wire the Touch-Lamp Dimmer to a mains transformer or power supply delivering 15 to 18 volts AC. One side of the 18V transformer, designated 0V, connects to the 12V filament lamp and then to the Load terminal of the Dimmer board. The other wire of the transformer then connects to the Active terminal on the Dimmer board. You also need a jumper lead to bridge out C2, a 0.lµF 250VAC capacitor. Fig.4 shows how the jumper lead is connected. Now apply power via the transformer. Nothing should happen although it is possible that the lamp may flicker. Now you should be able to get the lamp to turn on fully by touching the 0V wire with one hand and the "touch test" point with the other. The latter is marked on Fig.4 and is the junction of the continued on page 91 When the decorative plate is clipped into position, it should just make contact with the raised-head screw. We preferred the gold plate but you can use any colour you like from the HPM range. I I SC10-1-0789-2 Fig.5: here is an actual size reproduction of the PC artwork. TOUCH TEST Fig.4: by hooking the main Touch-Lamp Dimmer circuit up to a low-voltage AC supply, you can troubleshoot the circuit in complete safety. JULY 1989 35 TheAlnazing 3-in-1 Modular Tool At A Price Everyone Can Afford! It Drills! It Solders! It Screws! It's Rechargeable! Cat T-5712 See itat your nearest THE CREATIVE MUSIC SYSTEM It's New and it's at Dick Smith Electronics! It's astounding! The Creative Music Synthesizer card simply plugs into your IBM PC or compatible and gives you 12 channels (Voices) stereo music output and 32 preset instruments to choose from. Plus, there's a stereo amplifier to drive speakers, headphones or home stereo directly. You can actually define your own instruments, play background music while you work on your computer, create albums or your favourite tunes and play them in any sequence (great for non-stop party music) or compose your own music. And it allows you to utilize the new Sierra range of software! Cat X-2020 • ].2-Volcii Sfereo Music Synthesizer 299 5 ALL NEW! COMPUTER PERIPHERALS RS-232 Multilink Adaptor The CASIO fx-61 f A complete in-line tester/adaptor which makes complex and time consuming Serial connections a breeze. Comes with 25 pin male and 25 pin female connectors, jumper pads and wires, as well as 24 inline switches, for quick selection for any RS-232 configuration. 8 bicolour LED's tell you at a glance when you've got it right. Cat X-2654 Without doubt one of the most useful tools anyone working with electronics could have! With 27 of the most used electronics/electrical formulas built-in and a programming function which allows you to input your own formula. Includes 74 scientific functions, 10 digit display, programming functions ... it's unbelievable. s499s 'Voice Master' Sound Input Card Analogue to digital card lets you sample any sound, then view and edit the wave form. If you have 'Speech Thing' the recorded sound can then be played back. Comes with headset and software for experimenting with voice recognition. Set up to 256 different voice activated keyboard macros. Requires an 8-bit expansion slot (XT & $ AT compatible). Cat X-2038 199 'The Speech Thing' Digital Sound Synthesizer Adds sound capability to your PC! It's a full --="""""= featured 8-bit digital to analogue converter, audio amplifier and software system which is capable of creating almost any sound. Converts text to high quality speech. Just plug it in. Can be used in conjunction with the 'Voicemaster' (X-2038) to sample and edit digital sounds. Cat X-2036 Cat V-3828 s799s •. EJ .. . ···· G C!C:J ~- .• . EJ GJc::::J .. . " El .,. • " [3 ... G naau,a naaaa 1:111macm auaaa Copy Images Direct To The Screen! Handy Scanner HANov Now you can copy any image direct to your SCANNER computer screen with the incredible Handy HS-3000 Scanner! 105mm wide, Handy Scanner can be used with Hercules, VGA, EGA or CGA displays. Gives black and white and 3 x 32 quasi-tones. With high 400DPI resolution. Suitable for PC/XT/ ~f/ii:p)lJ AT and compatibles and comes complete with ;Desktop Publishing Editor. Cat X-3825 BOOKS FOR YOUR EVERY NEED Three Volumes! /Book World Radio Hand oo io I Linear book '89 Edition Up to date and complete listing of international radio and TV stations. It opens up a whole new world of listening action. Provides frequencies, addresses, call signs, IDs - you name it... virtually everything you'll need to know. 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Cat B-3635 Cat B-2400 s12es How To Beat urglar Bruce Stannard - 128 pages Not just electronics and alarms, it also delves into the crim's mind so you're ready to fight back! A must for every person with property to protect. Cat B-1040 $ 895 The Screwdraver This unusual book teaches the average person how to recognise and repair many of the most common CB problems, and how to get the best performance from a rig. Written in laymans terms, the reader is guided to the problem area by ~ B~;lt:Ji~ simple illustrated • ., instructions. B-2324 .~~g., Cat B-2208 s49es HowroeEAr THE BURGLAR 1 I • I . . ___ ...,. ·=··· ;.=.., ••· = -=·•J S.Ll,TELL! TE A NTH O LOGY s13ss For the advanced packet radio enthusiast, this ARRL publication is intended as a guide in the design and use of AX.25 Version 2 packet systems to ensure link-layer compatibility between systems. CatB-2403 il) XPRESS PHONE & MAIL ORDERS $ 1795 our Gatew_ay Interested in Packet Radio, but think detailed information is hard to find? Look no further! This new ARRL publication is an 'every!hing you always want to know book containing information that both packet-radio novices and experts will find useful and interesting. Cat B-2402 AX.25 Lin Pro o I 1 · ·• $2695 s29es 15th Edition The biggest edition ever! Comprehensive discussions and principles on virtually all aspects of antenna design and performance. Examples of hundreds of antennas with full construction details. No amateur should be without one! n book 1989 ARRL 00 " ·-·; ::.::"d"~•:~·.··~·.: . ~ The ARRL Antenna Handboo Another quality hard cover · edition of the ARRL Handbook for the radio amateur. Updated with all the latest information. With new projects, sections on oscilloscopes, spectrum analyzers, digital frequency synthesis and more. This handbook covers every aspect of interference to TV, stereo, radio, telephone, INTERFERENCE amateur radio, and CB HANDBOOK equipment. Helpful facts on how to locate and cure problems, how to work with the public, important 'do's' and 'dont's', case histories, as well / as safety precautions are ""'""' "" covered. Ham radio and CB operators will find this handbook invaluable when dealing with interference problems. B-2401 AX.25 AMATEUR PACKET-RADIO LIN K-LAYER PROTOCOL ♦ $1495 '------' 0 ~:j,:;J!j'J :D.S.!IJ~ s24es OUT NOW!! YOUR 1989/90 CATALOGUE ORD ER BV PHO N E: (008) 22 6610 ORDER BY PHONE - 008 22 6610 (LOCAL CALL FEE) OUTSIDE SYDNEY SYDNEY AND ENQUIRIES - (02) 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 New Release! Wireless Home Alarm System So Easy To Install! o Ho eless Five zone protection for your home that can be installed in no time - Without Wiring! It's the ideal security system for home units, apartments, etc - or where ever wiring is a problem. i That's right, all you have to do is plug it in, set the code and you've got instant protection. a With features like instant/delay modes, five zones of protection, 4 function modes, built-in speaker and provision for external speaker you get quality security in a compact unit which fits easily on bookshelf or bench . C s399 Yes, it comes as a complete security package. You get the central alarm unit, a remote controller, a remote Reed switch (for door or wi ndow protection), infrared sensor (for room or entrance surveillance) and mains adaptor! Cat L-5125 ADDITIONAL UNITS AVAILABLE Allows full control of your wireless remote security system. The remote controller fits in pocket or bag and allows you select any of the system's functions. Even has an emergency button. Cat L-5129 Remote THIS PROPERTY IS UNDER CONSTANT ELECTRONIC SURVEILLANCE t Ideal protection for windows or doors! A magnetic Reed switch with digital codi ng transmitter. Incredibly easy to install, just set the security code and forget it. Cat L-5127 Sticks to the inside of the window or glass door so they'll know you've Qot an alarm system and go pick on someone else1 Cat L-5311 WARNING Remote Infrared sensors are the best sensors you can get. For full room , hall or entrance protection this one offers 64 sq metre coverage and adjustable zone control. Has inbuilt transmitter. Cat L-5128 Large 245 x 270mm sign made from heavy gauge aluminium. Suitable for fi xing to wall, fence, etc. Cat L-5312 o 1 95 VALOEPLOS TEST INSTRUMENTS! Auto-Ranging 3.5 Digit With Memory! Budget Mini Multimeter Auto-ranging makes worker easier and faster - you don 't have to worry about what setting you 're on! This super meter also has auto-polarity PLUS high levels of overload protection on all ranges, Features include 'lo ohms' setting which limits o/c voltage for in-circuit resistance measurements, a handy buzzer which sounds at 1.9 digits, switch selectable autoranging (manual gives extended reso lution, transistor check, continuity and more! Cat 0-1516 An amazing Iittle multimeter that's ideal for anyone just starting out. .. or for anyone who gives their meter a hard time. 11 ranges, 2000 ohm/volt meter that fits easily in the pocket and is perfect for general test work. DCV/ACV: 10, 50, 250 & 1000. DC: 100mA. Cat0-1010 WAS $17.95 Now 99! 5 Save $101 Multimeter It's NEW/ Digital Capacitance Meter With Audible Continuity Tester. Compact and reliable with built-in buzzer for continuity testing. Even has a battery checker and 1OA DC range. Plus high sensitivity (20,000 ohms/volt), diode and fuse protection and 19 ranges plus dB. DCV: 2.5, 10, 50, 250 & 1000. ACV : 10, 50, 250 & 1000. DC (mA): 5, 50, 500 & 1A. A fantastic buy! Cat 0-1022 Now Just 5 29 I •. =-<at> ~ -- 1 95 - - ·.1,- - 1+ ! ::.:.~'<at> Hand-Held RC Oscillator Comes complete with test leads! A compact oscillator that's a must for the tool box. With 23 ranges of sine and square waves switchable between 20Hz and 1.5kHz plus x100 range. That's 46 settings in all. Continuously variable amplitude and -20dB attenuator gives you total control. Output is standard 600 ohms. Cat 0-1220 Reduced to $30 Off/ s399s Helps you care for your multimeter and keeps it free from dust, dirt, etc. Quality vinyl pouch with velcro seal. Suits Q-1516 multimeter and many other similar size meters. Cat 0-1513 s5 95 Agreat Ideal Multimeter Holster Impact absorbing case to protect your multimeter that's ideal for the bench of field work. Comes complete with belt and al lows you to carry your Q-1515 or Q-1516 multimeter around without it being a hassle. Cat 0-1522 Was $9.95 Now s79s f-), • 5 129 ~',, • -,~ e ~--=;;;;;~~ Bargain Protective Pouch Was $9.95 Only .~., ,:-; ···· 0 ,.;. -:. -~ Can be used to check tolerances, sort values, select precision values, measure unmarked capacitors, select matched sets plus measure cable, switch or PCB capacitances. Ideal for the workshop, hobby bench, schools, labs ... .anywhere! With 3.5 digit LCD readings over 9 ranges. Covers virtually all general usage capacitors. Battery operated, it's lightweight and comes with handy carry case and leads. Ranges : 200pF, 2nF, 20nF, 200nf, 2uF, 20uF, 200uF, 2000uF, 20,000uF. With over-range and battery low indicators, overload protection and carry case Cat 0-1222 With Bonus Offer/ Universal Panel Meters Quality universal 1OOuA panel meters in two popular sizes that can easily be adapted for just about any application - Volts, Amps. mA ... anything. Combine them with Shunt Pack (Q-2046) and meter instrument labels (N -5751). They operate over the range 100uA to 316mA and 1V to 100V. Higher currents are available by providing an appropriate resistance. SMALL MU45 With Bonus! Overall size 55 x 52mm. 45mm mounting hole required . Cat 0-2045 s1 &es LARGE MU65 With Bonus! Overall size 96 x 82mm. 65mm mounting hole required. Cat 0-2065 S2195 Bonus Offer! With every purchase of universal Panel Meter(s) you 'll get a BONUS Shunt Pack (Q-2046) for FREE! Hurry, this offer won't last! Pools/Lotto Selector : POOlS/LOTTO SELECTOR G An inexpensive, easy to build random number selector which may well be the best investment of your life. All you do is select the game you wish to play, Pools/Lotto/Lotto 44, push the button and it selects your winning numbers for you. Even has a systems select control for systems 6/7/8/9/10/11 / 12. Comes with pre-drilled and screened front panel. Cat K-3700 As described in Silicon Chip. FM Stereo Transmitter A miniature Stereo FM Transmitter powered by STEREO FM one 1.5V penlite cell. You TRANSMITTER can connect your CD player to the Mini-Mitter and then listen to your favourite CD's anywhere in the house, via your Walkman Personal Portable. ' Cat K-soo 4 As descri.bed .m s·1· , ,con Ch ,p. With lnfrared Remote Control Te1·etext Decoder Mkll FREO. • AOJ. The DSE Variable Power Supply The inexpensive way to get all the advantages of Teletext without taking a third mortgage on the house. You can have access to upto-date news, weather, sports details. TAB info, subtitles for the hearing impaired (not all programs) and much more. And now, we've made it affordable. Ideal for the service man, hobbyist, amateur, student etc. - everyone should have one. Simple to construct. Just Look.... Features: • Comes with Remote Controller • Simply connects to your existing VCR • Includes mains transformer • Comes complete with case and silk screened pre-punched front panel. Cat K-6360 • • • • • s299 l EFTRJGHT Variable 1.5 Volts to 15 Volts DC 500mA continuous Overload protection No mains wiring requ ired All necessary parts supplied including plug pack • Pre-punched silk screened front panel • Housed in attractive compact case • No drilling required Cat K-3200 NEW KITS SOON TO BE RELEASED!!! Touch Lamp Dimmer This unit can turn your light on and off or dim them just by touching the decorative plate. Unit is intended for dimming incandescent lamps rated from 25 watts up to a total of 300 watts. Cat K-3001 As described in Silicon Chip Extension For Touch Vehicle Exhaust Lamp Monitor Do you have a two-way light switch in you r This unit can be installed in your vehci le and home and would like them replaced with touch will detect any carbon monoxide gases which dimmers? We have just the thing for you. An may seep through into the cabin from your extension touch plate is connected in parallel vehicles exhaust. Driver will be alerted either to the K-3001 main unit, so that you can by a flashing led or an audible alarm. Cat K-4610 switch your lights on and off or dim them remotely. Cat K-3002 .-• -21-8399 -- - Square - -707 -4888 -----• • NSW Albury • Bankstown • Blacktown 671 7722• CampbeUtown (046)27 2199 • Chatswood Chase 411 1955 • Chullora 642 8922 •Gore Hill 439 53 11 • Gostord 25 0235 • Hornsby 477 6633 • HurstviHe 580 8622 • LiverJ)OOI 600 9888 • Maitland 33 7866 • M iranda 525 2722 • Newcastle 61 1896 • North Ayele 88 3855 • Parramatta 689 2188 • Penrith (047)32 3400 • Railway Square 211 3777 • Sydney City 267 9 111 • Tamworth 66 171 1 • Warringah Mall 905 044 1 • Wollongong 28 3800 • ACT • Fyehwick 80 4944 • VIC • Ballarat 3 7 5433 • Bendigo 43 038B • Box Hill 890 0699 • Coburg (03) 383 4455 • Dandenong 794 9377 • East Brighton 592 2366 • Essendon 379 7444 • Footscray 689 2055 • Frankston 783 9 14~ • Geefong 43 8804 • Melbourne City 326 6088 • Richmond 428 1614 • Ringwood 879 5338 • Springvale 547 0522 • OLD • Brisbane City 229 9377 • Buranda 391 6233 • Cairns 311 515 • Chermside 359 6255 • Redbank 288 5599 • Rockhampton 27 9644 • Southport 32 9863 • Toowoomba 38 4300 • Townsville 72 5722 • Underwood 341 0844 • SA• Adetaide City 232 1200 • Bevertey 347 1900 • St. Marys 277 89 77 • Elizabeth 255 6099 • Enfield 260 6088 • WA • Cannington 45 1 8666 • FremanUe 335 9733 • North Perth 328 6944 • Perth City 481 326 1 • TAS • Hobart 3 1 0800 •NT • Stuart Partl: 81 1977 BUILD THESE EXPERIM MAINS HUM SNIFFERS In this article, we present two simple circuits for sniffing out mains hum signals. Both can be built using parts from your junkbox and can be quickly assembled. By STEVE PAYOR These two circuits will let you check out the extent of electric fields permeating the average household, mostly originating from the mains wiring. Some of the things worth checking out are fluorescent lights, TV screens, appliance cords, power points and electric blankets. They are not intended to be practical devices for tracing mains wiring, however. Although appliance cords will register strong indications on these devices, wiring that is buried in walls is easily masked by the surface material. We'll have more to say about these performance limitations later. That said, both circuits are worth building, if only for their curiosity value. The simpler of the two let's you listen in to mains hum fields on a pair of headphones while the other circuit uses a meter to indicate the source of the hum. when the headphones are unplugged. The current drain is around 3-5mA. Without the optional earth lead, the probe will respond to both live and grounded objects, since your body will be picking up a certain amount of hum. If the circuit is grounded the probe will become silent when moved close to a grounded object. Thus it can easily distinguish between correctly earthed 3-wire appliances (eg, a toaster) and appliances which only have two wires (eg, some desk lamps). PROBE G The el-cheapo circuit Fig.1 shows the simpler of our two circuits. It consists of nothing more than a JFET in series with a battery and a pair of headphones. The circuit is best built on a small scrap of perforated board, with the gate lead of the JFET close to one end. No on/off switch is needed since the battery is disconnected + 1.5V Gffio VIEWED FROM BELOW OPTIONAL EARTH LEAD .,- Fig.I: this simple hum sniffer circuit uses a JFET in series with a battery and a pair of headphones. The circuit shown in Fig.I can be built up on a scrap piece of perforated board. Note that the JFET (at end of pen) is mounted close to one end of the board, with its gate lead nearest to the edge. 42 SILICON CHIP ENTAL Running the probe along the outside of a power cord will quickly tell you if the cord is plugged into a live socket. Not only that, but you can actually pick the active lead itself. Wiring buried inside walls is a little trickier. Often the conductivity of the wall material masks the exact location. It is not unusual for the hum to be spread over a general area of about half a metre in width. Let's now look a little more closely at the circuit operation. With the gate of the JFET left floating, the gate-source voltage tends towards 0V, due to leakage of the gate-source junction and surface leakage on the board between the gate and source wiring (the source wiring acts as a guard or shield between the gate wiring and the rest of the voltages in the circuit). With a gate-source voltage of zero, the JFET current is at a maximum. The impedance of the gate circuit is very high, so the electric field from nearby 240V 50Hz wiring induces a signal of several volts into the gate. Negative voltages turn the JFET off (somewhere between - 2V and - 8V for the 2N5459), positive voltages can't turn it on any more that it already is, and voltages above + 0.6V are clipped by the diode action of the gatesource junction. Thus a 10V p-p signal will cause the gate voltage to swing between 0V (approx.) and - 10V, giving a net negative bias to the gate and a reduction in current through the JFET. Try this simple experiment: plug a multimeter into the headphone socket and note the zero-signal current. Now bring a 50Hz source near to the JFET (your finger will do) and The differential hum detector uses a meter to indicate the direction of the hum source. You will probably already have most of the parts in your junkbox. watch the average DC current decrease as the signal increases. Now back to our buried wiring problem. You could try mapping out the field strength on the wall, using the multimeter instead of the headphones to get quantitative measurements. With enough readings, a contour map could be plotted and the contours would indicate the most likely location of the buried wiring. PARTS LIST 1 PC board, code SC04105891, 168 x 88mm 1 centre-zero meter movement, ± 1 00mA full scale sensitivity (see text) 2 2N5459 JFETs (see ,text) 1 2k!J horizontal or vertical mount trimpot 1 1 .5V AA battery holder 1 1 .5V AA battery 1 miniature toggle switch or slide switch 1 perspex handle to suit There is an easier way - two detectors placed symmetrically either side of the wiring will both pick up the same amount hum, but if one is a little closer than the other, the balance will shift. A pair of detectors with a meter to measure the difference between them should, in theory, be able to zero in on the buried wiring. Differential detector This leads us to the differential hum detector as shown in Fig.2. The 2k!J trimpot sets the initial balance between the zero-signal JFET resistances. If both probes pick up the same amount of hum, then both JFETS will turn off by approximately equal amounts and the meter needle will remain centred. If one probe picks up more hum, the current through its associated JFET will be reduced and the meter is wired so that the needle swings in the direction of the probe receiving the most hum. Thus the needle actually points to the source of the hum. ]UL Y 1989 43 Choosing a JFET s:\ 1.5V;r.. GUARD GUARD 250•0·25QuA G<at>D VIEWED FROM BELOW DIFFERENTIAL HUM DETECTOR Fig.2: the differential hum detector circuit. If one probe picks up more hum than the other, the current through its associated JFET is reduced and the meter needle swings in the direction of the hum. Layout is important in a circuit like this. Symmetry of capacitance must be maintained and DC leakage currents must be controlled with guards. If you are using our PCB to build this device, it is best to obtain it undrilled since a number of hole locations have been provided to accommodate a variety of components. So dig deep into your junkbox and see what you can press into service. Meter movement The board will accommodate a centre-zero tuning meter (as sold by DSE, Jaycar, Altronics, etc) in the lowest two holes. "Edge" meters can be fitted to the middle two holes while the upper holes, drilled to 3mm, will accommodate an MU45style unit which can be bolted directly to the board. Suitable meter sensitivities range from ± 50µA to ± 250µA full scale (optimum is about ± l00µA) . Don't worry about which way around the + and - connections are arranged - the PCB has four pads marked A, A and B, B which effectively form a double-pole, double-throw (DPDT) switch to reverse the meter connections if it happens to swing the wrong way. Start by soldering pads B and B. If the meter subsequently swings backwards, desolder B and B and solder A and A instead. Above: the two probes are nothing more than fancy copper patterns on the back of the PCB. At right is another version of the detector using 2N5459 N-channel JFETs and a small centre-zero tuning meter. 44 SILICON CHIP 2N5459 N-channel JFETs are recommended but lower current 2N5458s or 2N5457s can be used with a 5kQ trimpot and a lower current meter (eg, ± 50µA). P-channel JFETs such as the 2N5460 can also be used. In this case, reverse the battery holder and solder pads A and A for the meter. Note that the pin connections for P-channel JFETs are different and the leads will have to be bent so that they fit the board correctly. On/off switch Either a toggle or a slide switch can be used here. In addition, optional solder pads are provided so that " up" can be either ON or OFF as you please. Trimpot & battery holder Any trimpot from 2kQ to 5kQ, horizontal or vertical, can be used, preferably something with a plastic knob or thumbwheel. A 5kQ or 10kQ pot could also be used provided it is shunted with a pair of 2.2kQ or lkQ resistors. The single cell battery holder is available from Tandy Electronics (Cat. 270-401). Alternatively, this item is also available from Radiospares (stock number 489908). Perspex handle An insulating Perspex handle How to Bend Perspex ZONE BEING SOFTENED (OD BOTH SIDES) PERSPEX To bend Perspex, you have to heat a localised strip to a temperature of around 120°C. You can do this with a hot air gun such as a heatshrink gun or electric paint stripper, or possibly even a hair dryer'. You can also use an electric bar radiator or a hot stove element as shown in Fig.3 . You will need two sheets of insulating material such as Fibro (or asbestos cement, if you can) or, in a pinch, heavy gauge aluminium to mask off all but the desired bending area. Perspex absorbs long wavelength infrared quite well. It won't actually melt but at the correct temperature goes "rubbery" and is easily formed. Overheating will blister and discolour the surface so don't overdo it. \ I ALUMINIUM------' SHEETS :-,-::=----,--- ''.\!// \\\/// \\\i/f \\\JI/ ~ c:::::::i c:::::::J RED HOT STOVE ELEMENT c::::] 6mm OR LARGER GAP (ABOUT 2x SHEETTHICKNESS) c::::] f Fig.3: Perspex can be easily bent by heating a narrow strip of the material to about 120°C. flt\ tr~s 2N5460 VIEWED FROM BELOW Fig.5: this diagram shows the pinouts for the 2N5460 Pchannel JFET. You will have to bend the leads so that it fits the board correctly. Fig.4: this version uses N-channel JFETs and an MU45-style meter. Don't forget to bridge the appropriate pads on the back of the board associated with the meter and the on/off switch (see text). can be fitted using the same screws and nuts used to secure the battery holder. If you have never bent Perspex before, ref er to the accompanying panel. Whether you hold the unit by an insulated handle or by the meter case depends on what sort of field you are standing in. Sometimes you may need to earth yourself or even hold the unit by the battery to earth it as well. In short, you will have to experiment to determine the best way to hold the unit for a given situation. Start by bridging the B pads on the back of the board. If the meter swings the wrong way, desolder them and bridge the A pads instead. You must also bridge one set of pads associated with the on/off switch. Performance & limitations The unit may give misleading readings when overloaded. Too strong a signal will cut off both JFETs so keep the signal strength within reasonable limits by varying the way you hold it. In most cases, holding the meter case between outstretched finger tips, with no earthing, will give the best results. Appliance cords will register at a distance of 100mm or more while fluorescent lights will register at 200-300mm. Wiring in walls may be masked by metal conduits, metal plates in the wall or door frames, or uneven conductivity in the wall material or surface coating; For these reasons, the unit JULY 1989 45 ~ I • ,.. jl - lo~~-- L _J Fig.5: the PC pattern is designed to accept three different meter types and virtually any size trimpot. The meter here is pointing in the direction of the mains switch wiring. Note that misleading results will occur if the JFETs are overloaded by strong hum fields. In most cases, holding the meter case between outstretched finger tips will give the best results. 46 SILICON CHIP should only be used to confirm the presence of mains wiring, not its absence. Static charges on surfaces may also present a problem in dry areas. Try this: wave a plastic bag or polystyrene "biro" near the electrodes. Even if these objects have just been sitting around, picking them up will probably charge them to several thousand volts. The RC time constant of the JFET gate circuit is determined by the board and junction leakage and is of the order of several seconds. This means that you should move the detector very slowly when in the presence of large accumulations of static. Some improvement can be obtained by fitting a resistor between the gate and source of each JFET but, unfortunately, to maintain full sensitivity at 50Hz, the resistor value needs to be around 2-10 gigohms. This is why we elected to use the board leakage instead. By the way, it will be necessary to minimise this leakage by removing the solder flux around the gate connections of the JFETs. This can be done by cleaning the board with a cotton bud moistened with methylated spirits. [§;I BOOKSHELF Loudspeaker systems design reference The Loudspeaker Design Cookbook, by Vance Dickason. Third edition 1987, 2nd printing 1988, published by the Marshall Jones Co, Francestown, New Hampshire, USA. Soft covers, 217 x 281mm, 96 pages. ISBN 0 8338 0194 5. Price $37.95. This book is the best we have seen in a long time in bringing together all the current theory employed in loudspeaker design. Naturally, it leans heavily on the papers of Neville Thiele and Richard Small and a lot of subsequent papers by other authors who have enlarged on Thiele and Small's work. If you're interested in loudspeaker design though, don't expect any easy answers from this book. It contains a lot of theory and presents a lot formulas and tables to help with the design of optimum loudspeakers. It really should be thought of as a distillation of current loudspeaker design practice into one convenient volume. It has 8 chapters in all, listed as follows: Chapter 1, on closed box low frequency systems; Chapter 2, vented box low frequency systems; Chapter 3, passive radiator low frequency systems; Chapter 4, transmission line low frequency systems; Chapter 5, cabinet construction, shape and damping; Chapter 6, mid and high frequency drivers; Chapter 7, crossover design, passive and active; Chapter 8, loudspeaker testing, manufacturers' listing. I am not going to go into an indepth review of the treatment of each chapter as the space is not available. Suffice to say that the four enclosure types (sealed, vented, passive radiator and transmission line) are all presented in an objective way without the author appearing to favour any one approach. Suffice to know that after reading this book, if you know the free-air resonance and Q of a woofer, you can make an intelligent choice between a vented or sealed enclosure and then design the box to get optimum performance. Designing the box is only a small part of the battle though, as we can attest from some of our own recent work which has yet to bear fruit. You can design a box along the right lines and still end up with a design that sounds lousy. You also have to make some canny choices in the midrange and tweeter units and design the crossover network. Happily, this book gives the good oil here too. I should mention here that we often get requests for the design procedure for air-cored inductors for crossover networks - this book gives it. However, you don't have to do too many calculations to realise that low resistance inductors of more than a millihenry take a great deal of expensive copper wire .. That's why iron and ferrite cored inductors tend to be widely used. In summary, this is a very useful text for anyone interested in designing loudspeakers. Now there's just one problem: anyone know of some good drivers that don't cost an arm and a leg? Our already much-thumbed sample copy came from Dick Smith Electronics. Their retail price (Cat. B-3613) is $37.95. Get yours now before they run out. DXing on the shortwave bands Low Band DXing: Your Guide to Ham Radio DXcitement on 160, 80 and 40 Metres, by John Devoldere. Published 1987 by the American Radio Relay League. Soft covers, 218 x 277mm, 266 pages. Whether you are an amateur radio operator or a budding shortwave listener, this book has some really good reference material on long distance communication. It is written primarily for amateurs but that should not put off anyone interested in shortwave listening. It has 8 chapters in all, in which the whole subject is treated in great detail. Chapter 1 is on low band propagation and how it is affected by the time of day, time of year and the sunspot cycle. Chapter 2 is on antennas and the pros and cons of the various designs - big chapter this one. Chapter 3 is on transmitters while chapter 4 is on receivers, which will be of more interest to SWLs continued on page 91 -_\~ '{..I" . n'!. ..,. , ~~ c,~'{..I",'i)<:i ~ ~ <:,'!,<:, '{..I"' c,r c,~'~"' ~~\; \«,,~ ~e:, ~·. ..,,·,,· , ~~~~~ ~<i, ~ c,~\. ,;,'!, __ / 7 A.-.\\.~ ~, , , • 4.<(,,~ :1\"' \,~;,,,~· / v -,_I"\ ,,_ ~7 FM ANTENNAS FAMOUS WD40 NO\VAVA We've got 'em all Discover the world·s most useful product. WD40 combines the functions of conventional light lubricant, penetrating oil, rust preventative, moisture repellant. metal cleaner, silicone spray and even household cleaners. and it's safe to the environment • RemCNes moisture to start engines • Cleans & protects tools • Cleans bike gears for smooth operation • • Dissolves tar on cars • Loosens rust & corrosion • Stops squeaks on hinges I I • Lubricates locks ···.... I ,./ • Lubricates pots ··•... ./ • etc .. etc .. etc .• etc .• etc.. ······......··/ 2 SIZES 91 Element Receives all band 4 and 5 channels through 21 to 69. Ideal for fringe areas. Includes balun for 75 n cable. Max gain 16dB. Cat. LT-3182 $139 43 Element Suits both channel 4 and 5. Ideal for medium signal reception areas. Includes balun. Max gain 13dB. Cat. LT-3181 $75 T~e! byE A!~n~ ! ~ !nd 5. Includes balun. 8d8 gain. Cat. LT-3178 * 150g Cat NA-1 015 300g Cat NA-1016 $3.9 $5.50 626· S'I' SPEED 150ns NORMALLY $22 $39.95 NOW $ 5 10+ $12.so Cat.ZZ-8440 ~~~~ EASY TO INSTALL Simply mount above or below your existing VHF aerial and connect to existing cable with a diplexer. Cat. LT-3014 $12.95 r-r.xiHA"icrocKTiinc1<,focK-, -REDUC VIFA SP . ' ~ .II1 you're tired of looking at that mantle clock reading ten past one (and it's not), why not fix it! It will take about 10 minutes with one of our clock modules. We have four types. Just remove the old mechanism, Iyou throw it in the bin and replace it with an accurate quartz crysta! movement! We even have ones that play Ithe old fashioned tune (Westminster Chime) and then chime the hour. Also ideal for making your own SA-50 2 way bookshelf kit with cabinets and crossovers. 30W rms handling. Cat. CS-2450/CS-2452 l sTANDARD MOVEMENT SAVE $30 ONLY $369 *-: custom clock face. I•Very compact 56 x 56 x 15mm • Powered by 1-AA battery I• Supplied with 3 different sets of hands lcat. xc-0100 j •· . · I PENDULUM MOVEMENT/QUARTZ CLOCK (,.: >·~ · . -- 1 IdeaI clock mechanism replacement for a small pendulum clock, your own pendulum. sets of hands supplied · Ior• 3create 1• Uses 1-AA batt$ery 0 ., ,- (:i _' o_,,.,J~ \ 1 ca1. _xc-0103 16 • 9 5 , , c-,;· · ,t0 .. IMELODY CLOCK MOVEMENT .:.. ! / Two different modules are available. Both chime the hour after playing their tune. plays Westminster chimes each hour then gongs the hour (i.e. 7pm - 7 gongs) IXC-0106 XC-0107 plays a different melody each hour. then gongs the hour. IBoth units are supplied with: Q. ,, • : , 1• Clock movement • Speaker and battery holder (3-AA batteries required) I•3 sets of hands Cat. XC-0106 Westminster chimes ICat. XC-0107 12 melodies 12V CAR ANALOGUE CLOCK MOVEMENT HACK , 6000 POWER AMP HEATSIN As used in the AEM6000 power amp. It can also be used as the sides of a 4 unit rack case for high power rack mount PA amps! Die cast. Total length 352mm - height 166mm. Total depth 61mm number of fins 20. Cat. HH-8620 AUT01'1ATIC TELEPIIONE DIVEi . I location. (Two exchange lines are required). The unit will divert either of the incoming lines I Supplied with 240V plug adaptor. mstructIons and telephone leads. Double adaptor Cat. YT-6020 $4.95 may be required. Measures 190(W) x 11 O(Dl x 35(Hlmm. I Cat. YT-5510 _ , I $24 9 · I ONLY $9:!~ Convert the broken/unreliable or inaccurate mechanical clock in your car to space age precision. Made in west Germany by VDO. the module measures roughly 45 x 38 x 40mm deep. The compact size virtually ensures that it will fit in any space! Quantity strictly limited. NEGATIVE ION GENERATOR ONLY $29.95 Cat ST-3000 MASSIVE SCOOP PURCHASE!I This device diverts an incoming call e.g., to unattended office. surgeryorhome-toanother \. ___________ c:_x:: 240 VOLT - SAVE $50 Cat. YX-2905 METAL TOR Uses 2 AA batteries. 70 times brighte normal torch. adjustable beam. includ DON'T PAY $19 $55 I ONLY $19.95 each I I I , . .. ..· I '\,,° a pair . $12.95 : * ~;;'d):;2,>,:"-"''-7:.s,-,c~ - - MONITOR MADNESS ~ ****** Another distress stock purchase ! This time a quantity of Sa msung brand 12" composite computer monitors. Ava ilable in either green or amber. Specifications Picture Tube Mode Composite Input Signal ■ Polarity ■ Level ■ Impedance Active Video Period ■ Horizontal 12ZBY31N (12' diagonal 90° deflection) Composite Active Display Area Display Characters Input Connector Co ntrol s ■ Front Negative sync 0.5-2.0V pp ■ Rear ■ Internal 75n Mechanical and Environmental Operating AmbientTempera ture ■ Power Supply ■ Power Consumption ■ External Dimensions ■ ■ Vertical ■ Video Band 39.11µ-; max. 12.21ms max. 25MHz (-3dB) ■ Weight ■ Vertical 15.75kHz 60Hz Width Scanning Frequency ■ Horizontal 216(H) x 160(V) 40 characters x 24 lines (7 x 9 cell) RCA Phono Jack Power on/off, contrast V-hold, V-size, Brightness V linearity, H hold, H linearity, H width, Focus +5° through +40'C 11 5V, 230V/60Hz, 50Hz 50Wmax 3121W) x 300(H) x 307(0)mm Approx 7.5kg. $99.50 SAVE $50 ONLY LIMITED STOCK - BE QUICK GREEN Cat. XC-3000 AMBER Cat. XC-300 1 DISK DllIVE BARGAIN Another surplus stock purchase. Brand new Chi non brand model F2-502 51/4' 360k made in Japan drives. These sell discounted for $239 and normally about $279. We have a limited quantity for only $149 each. Brand new • 3 month warranty Cat. XD-4600 SORRY NO TIME FOR A PIC. $149 We also have other computer equipment at our Gore Hill store. Call in and have a browse. All at silly prices. MINSTREL 2-30 SPEAKER KIT ULTRASONIC HUMIDIFIER This unit rehumidifies air automatically by an ultrasonic mist evaporator. You can adjust the humidity in your environment in the the range 30-90% R.H . It simply plugs into the power point and draws little power. It has a large water container .(6.75 litres) and switches off automatically when dry. The mist output is free of dust as the air drawn into the unit is filtered. Great for gardeners who need to keep the humidity up in greenhouses for their palms. ferns and plants in general. Also ideal ~~~-= 240V operated. 55 Cat. YH· 00 1 ~;~-------~==~ $129 LESS 10% FOR JULY ONLY! WAS $149 in 1986 Cat CS-2542 NOW ONLY $99.50 ~~~ 3s 1, . f : I I SYDNEY - CITY PARRAMATTA CONCORD VISA $149 - 1 ::( Ref: Silicon Chip Feb '89 This is a co-operative speaker project between Silicon Chip and Jaycar. Usi ng an 8' woofer and a dome tweeter with prebuilt crossover unit the system has been acclaimed for its superb sound reproduction. The cabinets measure 480(H) x 303(W) x 290(D)mm. For further info see our 1989 catalogue. Pair of spea kers and crossovers Cat. CS-2540 Cabinets (pair) =.,_~ HURSTVILLE HEAD OFFICE 115ParramanaRoadConcord2137 Telephone (02) 747 2022 Te lex 72293 FACSIMILE (02) 744 0767 MAIL ORDER VIA YOUR 117 York St. (02) 267161 4 Mon-Fri 8.30 · 5.30 Thurs 8.30 pm· Sat 9 · 12 355 Church St (Cnr Victoria Rd) (02) 683 3377 Mon-Fri 9 • 5.30 Thurs R.30 pm • Sat 9 • 4pm 115 Parramatta Rd (02) 745 3077 Mon-Fri 8.30 · 5.30 • Sat 8.30 • 12 121 Forest Rd (02) 570 7CXXJ Mon-Fri 9 · 5.30 Thurs 8.30 pm • Sat 9 • 12 MAIL ORDERS PO. Box lB5 Concord2137 HOnlNE 02 7471888 FOR ORDERS ONLY TOLLFREE (008) 022 888 ff $25- $49.99 $50- $99. 99 OVER$100 s 3_75 $ 4.50 $ 6_ 50 $8.00 ROAD FREIGHT ANYWHERE IN AUSTRALIA $13.50 GORE HILL BURANDA QLD MELBOURNE-CITY SPRINGYALE VIC POST a PACKING $l0- $24_99 188 Pacific Hwy (Cnr. Bellevue Ave) (02) 439 4799. Mon-Fri 9 • 5.30 Sat 9 · 4pm 144 Logan Rd (07) 393 0777 • Mon-Fri 9 · 5.30 Thurs 8.30 · Sat 9 · 12 Shop 2, 45 A'Beckett St City (03) 663 2030 Mon-Fri 9 • 5.30 Fri 8.30 - Sat 9 • 12 887-889 Springvale Road Mulgrave (03) 547 1022 Nr Cnr. Dandenong Road Mon-Fri 9 • 5.30 Fri 8.30 - Sat 9 • 2 You need a pal to deal with PAL When the PAL colour system was first introduced we all burnt a lot of midnight oil trying to bridge the gap from NTSC theory to PAL theory. While most of us felt we had succeeded, time and day-today practical work have taken their toll. Now, when this theory might help, our memory fails us. Nothing very exciting happened on my own bench this month, so the following story comes from my colleague J. L. in Tasmania. It tells how he encountered the need for some PAL theory. Here's J. L.'s story: There are some television sets that I don't like servicing. One such set is the Sharp model C1831X (and I can hear a lot of my colleagues saying "Hear, Hear!"). It's true that many of us have had trouble with this chassis yet others have had no trouble at all. It's almost as if the set has a mind of its own and doesn't like anyone wearing glasses, or a bald head, or false teeth. On the other hand, chaps with beards seem to have no trouble at all with this set, so maybe we should all grow long hair! There are a number of common problems in the vertical section of the C1831X which are fairly easy to cure, so long as you are careful. Unfortunately, as you slide the chassis out of the cabinet, it is all too easy to allow the contacts on the underside of the vertical oscillator chip to touch the metal rails on which the chassis moves. It doesn't seem to matter whether the power is on or off; you don't get a second chance and the chips are quite expensive. Another problem is with the wire-wrap interboard connections. You can only flex a single core wire so many times and if you are chas- ing a difficult fault it is easy to bend the wires once too often. They tend to break inside the insulation and you don't know until you switch on and some part of the set no longer works. I heard of one case where a vital earth link broke and somehow allowed the 200V rail to go to chassis through the 12V rail. It did dreadful things to every IC and transistor in the set! So with this sort of background to the C1831X, and the fact that my glasses steam up every time I see one, I am quite happy to concentrate on other models and leave this particular Sharp model to those who enjoy head-butting brick walls. Oh boy, a C1831X But sometimes you just can't refuse to do a job and the story that follows tells about one such exer- ,_.T\·HS 1\MG: SH~ C.A MC:., NOi" -ro C.OME. & FI~ i\-\~E-r, SU\ i'O ,A~E n- AWA'-{ FOR '""C:R ..... 52 SILICON CHIP .d ~ ~ ~- iHE. 'PlCtURe:.. WPS V ~ DARK & SH-€ C.OUL..'D ONL.'1 WlrrCH rr ITT" \\l\GH-r: ... cise. When a customer gives you an old set for junk there's a strong temptation to get it going again, if only to see if it can be done. And if it's a C1831X, then you're stuck with it! This particular C1831X belonged to a well-liked, elderly customer and I had attended to it a couple of times in the past. The faults were never very serious but I was always apprehensive whenever I heard her on the phone. This time she called me, not to come and fix the set but to take it away for her. It seems that a small insurance policy had matured and rather than bank the money and complicate her pension status, she bought a new set to replace the aging Sharp. It had been playing up a bit before it was retired. The picture was very dark and the owner could only watch it at night. She guessed that the picture tube had gone but that I might get some useful parts out of the rest of it. Hence the call. I wanted a Sharp C1831X like the legendary "hole in the head" but out of respect for a valued customer, and at the first convenient opportunity, I called to collect it. The last time I had seen the Sharp was some six months earlier and it had then displayed quite a good picture. I wondered if it really had dropped its bundle so suddenly or was there a more logical reason for the dark picture. Back in the workshop I fired it up and saw what I had suspected all along. The picture was truly low in brightness but the chroma was more or less normal. It had to be an open circuit bypass capacitor or feed resistor in the supply rail to the video output transistors. This kind of fault is common in circuits where the video output supply rail is bypassed with an electrolytic capacitor, particularly low value types of about 10µF or less. Low value electros are notoriously unreliable after a few years but higher values can also fail. It didn't take me long to confirm that the video output transistor collector voltages were very low indeed. This seemed to discount the capacitor theory because usually, when the bypass capacitor is open, a multimeter shows a rail voltage at somewhere around 50 to 75% of the normal voltage. During the flyback blanking period the rail rises to quite a high level because there is minimum load on the supply and no capacitance to absorb the supply pulse. Once blanking comes off, the video output transistors draw on every scrap of available energy and the rail voltage plummets. A multimeter averages these two levels and shows a rail voltage considerably higher than the true voltage during the line period. (Picture content also has a big effect on the rail voltage in the fault condition. A white screen loads the rail heavily, while a black screen draws little current and the rail can rise to almost normal value). In this case the voltage was very much lower than the condition described above, and also more consistent. This suggested that it was more likely that the pulse which generates the rail voltage was not even reaching the capacitor. And so it proved to be. R952, a 4 70 1W resistor feeding the capacitor (C104, 47µF), was reading several hundred kilohms and the surprising thing is that there was any voltage at all on the output collectors. And C104 was faultless . Hanover bars Replacing the resistor soon had the brightness back to normal and the set was displaying quite a reasonable picture. Except for one thing - severe Hanover bars. These bars are an obscure fault that occurs only in the PAL colour system. In PAL the phase of the transmitted chroma signal is alternated line by line and this is achieved by alternating the phase of the R-Y signal. So, if the phase of the red signal on line 1 is, say, 103°, then the same signal on the next line is shifted by 180° to - 77° (using the accepted chroma-phase scale), and so on down the picture. On playback, an identification signal is used to determine which of the lines is in the 103 ° phase and this line is displayed as is. The next line (at - 77°) has to be inverted, back to 103°. The circuitry used to perform this function is commonly referred to as the PAL switch. If this switching fails, the picture shows one line normal red, the next line (180° out) as cyan (bluish) and so on. The effect was first noted in Hanover, Germany, where PAL was developed, hence the name. It's sometimes called a venetian blind effect. TV TEST EQUIPMENT YOU NEED NOW!!! SHORTED TURNS TESTER (Built-in Meter) For checking EHT transformers including Split Diode Type, Yoke Windings and Drive Transformers. $78.00 + $3.00 p&p HI-VOLT AGE PROBE (Built-in Meter) Reads Positive or Negative 0-50kV Designed for checking TVs, microwave ovens and any high voltage equipment. $84.00 + $5.00 p&p TV TUNER REPAIRS Repair & Exchange (Philips ELC 2060) $17.00 + p&p Repair (Philips UV 461) $18.00 + p&p Repair & Exchange (Philips Turret) $18.00 + p&p Repair (AWA MITS Varicap) $18.00 + p&p Repair (Pye LM031 Turret) $18.00 + p&p P&P $2.00 Cheque, Money Order, Bankcard or Mastercard: Y.V.TuNERs) 216 Canterbury Road, Revesby, NSW 2212. Phone (02) 77 4 1154 ]UL Y 1989 53 I fed in a colour bar pattern from the generator and it showed quite distinct bars in the cyan, green, magenta and red sections of the pattern. The yellow bar was unmarked, a significant point that escaped my notice initially. Any set can show Hanover bars if the delay line settings are out of adjustment so the first thing I did was to go over all the adjustments as defined in the manual. This made no difference at all so I turned to the ident circuitry and looked for a more obscure answer. The PAL switching is carried out in the demodulator chip, IC804, and is driven by a multivibrator running at half line frequency. If the multivibrator starts up in the wrong phase, the reds and greens in the picture will be displayed in their complementary colours. To avoid this, an ident circuit looks at the instantaneous phase of the colour burst and develops a 7.8kHz pulse which steers the multivibrator into the correct phase. It was this circuitry that I looked at next. The manual gives instructions for adjusting the amplitude and phase of the multivibrator con54 SILICON CHIP trol circuit but I am sure that there is an error in them, although I haven't heard of any errata for this model. On page 18 the amplitude alignment calls for adjustment of T807 for maximum response as in waveform "B" which turns out to be a square wave with a curious bump on the top. Then on page 19 the next step uses the same T807 and is supposed to match the response curve "A", an H/ 2 sine wave. Even if waveforms "A" and "B" are swapped to make them agree with the instructions, the result is still ambiguous. The second adjustment is supposed to position the bump in the centre of the square wave. But this reduces the amplitude of waveform "A". If "A" is adjusted to maximum, as instructed, then the bump is shifted right off the end of the square wave. In the end I ignored the first instruction and settled for the centralised bump. This proved that the ident circuit was working but did nothing to alleviate the Hanover bars. Once I had satisfied myself that all the circuitry was working correctly, I began to suspect some subtle malfunction in one of the components - something that would give the right measurement but not process signals in the proper manner. So I started to change components. I had an old C1831X chassis that was known to be have been a good one so I lifted various parts and dropped them into the problem chassis. ICs, coils and transformers, transistors and even the chroma delay line all went into the villain, but nothing made any difference. By this time I was pretty desperate. The set had cost me nothing in cash but had piled up a considerable debt in hours. The pity of it all was that the set promised to show a very good picture, if only I could get rid of those (expletive) Hanover bars. And by this time I had another customer who wanted to pay cash for a good secondhand 44cm TV set; eg, a Sharp Cl831X. During all the preceding measuring and testing, I had frequently looked at the video waveforms on the output collectors. The blue waveform was the classic on-off shape and only proved that the blue channel was responding exactly as it should. The red and green on the other hand, were showing a curious sloping waveform that should have alerted me. One problem that comes from working on your own set is that the job is done in short bursts, when customer pressure eases off. So you often find yourself repeating something done several days earlier, and the time so wasted begins to pile up. Also, working so close to the problem for days and days tends to blind one to obvious clues. And so it was that I had to turn away the cash customer and put the old Sharp on the forget-about-it shelf. I had spent as much time on it as I was prepared to and the set would now have to be junked. It had cost me nothing in cash but 15 hours doesn't come cheaply even if it's my own time. A few weeks later, I was talking to a colleague about the set and its TETIA TV TIP Hitachi PA3-A Chassis (CEP288 etc) Symptom: l.,ow height. If height readjusted when the set is warm, it will still be low for a while after switch-on. Recovers height in two to five minutes. 20 volt rail varies from 1 6 to 1 8 volts during warmup but does not reach 20V. Cure: C753, a 1 0µ.F 25V electro defective. Capacity is very low Hanover bars. He is a college instructor and knows colour TV theory very intimately but he gets few chances to actually service a faulty set. He asked if he could have a look at it and I readily agreed. A few days later we set it up on his bench and the first thing he noticed was that the yellow bar was clear of the fault. This was no great shakes to me but to him it suggested that the ident was working at the beginning of each line but fading as the line progressed. And when he looked at the video output waveforms, the sloping characteristic, which I had noted but dismissed, confirmed this interpretation; the ident signal was losing its grip as each line scanned across the screen. · when cold and increases only slightly as the set warms up. This is the input capacitor to the 20V rail filter and its loss changes the filter to inductive input with consequent lower output. TETIA TV Tip is supplied by the Tasmanian branch of The Electronic Technicians' Institute of Australia. Contact Jim Lawler, 16 Adina St, Geilston Bay, Tasmania. There are no demodulator chip waveforms in the manual so one has to fall back on theory to determine what should be happening. The demodulator has to be supplied with chroma, a 4.43MHz reference signal, and a 7.BkHz ident signal. If all of these are present then the chip should produce the appropriate outputs. I had checked the presence of chroma and the 4.43MHz reference and had found what I thought was the ident signal. But I was wrong. That ain't right My friend confirmed the first two signals as present and correct but when he looked at the ident, on pin 11 of IC804, he said "Oy, that ain't right!" He was looking at a series of WE. C.OUL.t>N~ ) f'IIIJC> PN'lONE- ~~\~'t'e;.R ~P\N ~OU ~~ -~ e) ~!_l- 2~~~/\< A'RE'I'm GLA1) 11-\e:RE: 'SOME: ?eopt.£. S'R\GH-rER "ffi-~N N\£., O™ER vJ I-SE 1\-\5 WO'RL--.D WOU'-l> '8~ NE.C...K 1)€et> \N C> lJ O TE.L.-L-\.f 'S () ••. short pulses, first positive going then negative going, at 7.BkHz. These were what I had assumed to be the ident pulses but he knew that these short pulses could not properly control the phase reversal switch inside the chip. In fact, what is needed is a full square wave with a solid, steady voltage to hold the switch in whichever position it should be. The short pulse could only flip the switch but couldn't hold it in the right phase. Hence the clean yellow bar, on the left of the screen. This corresponded in time to the first few microseconds after the switch had changed over, before it drifted to an indeterminate position for the rest of the line. The square wave is also, in some way, responsible for setting the DC output levels of the R-Y and G-Y signals. In the fault condition, the pulse was enough to establish the right levels at the start of each line but then they drifted to some arbitrary level before the next pulse reset them. This explained the sloping waveforms I had noted in the red and green channels. In the end, the fault was so easy to find that it was ridiculous. It was C845, a 0.47 µ.F electro between the multivibrator output and the demodulator chip. On the capacitance bridge it read 270pF, far too little to pass a solid square wave. (It was apparently differentiating the original square pulses, converting them to spikes. Ed). As I said earlier, you can get too close to the job and miss the obvious clues. Then again, it helps to be the full bottle on theory when the manual offers no help. I thought the pulses only had to flip the switch, not hold it in position as well. I'm glad there are some people brighter than me, otherwise the world would be neck deep in dud tellys ! Well J. L., I've learned a lot from that and I'm sure our readers have too. I can't recall having encountered the Sharp 1831X, at least not in any complicated way, but I'll be on guard if I ever have to slide one out of the cabinet. I'll watch those wire wrap leads too. As for the Hanover bars - that was really nasty. No wonder it fazed you. (Ouch! - sorry about that).~ JULY 1989 55 AT/386 hard/floppy disk controller CAT2310W • Standard double sided/double density featuring brushless DC motor design. • Track to track access: 3ms • Transfer rate: 250Kbits/sec • Recording method: FM/MFM • Demensions: 41 mm(H) x 146mm(W) x 203mm(O) (not including font panel) • Power consumption:+ 12V/390mA (startup). 21 0mA (idle) , +5V/460mA $175 • WD-1006-MM2 chip set. • Ful ly compatible wi th WD -1006-MM2 card. • Controls 2 ST506 MFM ha rd and 2 floppy disk drives. • Hard disk drives can be up to 16 heads and 2048 cylinders. • Interleave 1:1. full track buffer. • Bus speed - 16 MHz. • Data transfe r rate - 440 KB/second . • Floppy disk drives can be 360Ki 1.2MB/720Ki 1.44MB. • Built-in CRCIECC • Card size - 21.5 x 10.7cm CAT D0 1035 $225 $775 COMPLETE RANGE CAT PD3 142H New removable hard disk. The portable hard disk offers con venience and security. The perfect .··' /-~=- /, _,. / backup data transportation solution for network backup . normal backup. transfer of work to another PC . Fits standard 5.25 inch slot. 42MB. 28 MSec dnve and Port adisk carri er and cables included $1090 Floppy Drives NEC 360K 5.25 inch floppy drive. CAT 001053 ICl Ml O IC256K 12 IC256KBO IC28710 IC2876 IC2878 IC4256K 10 IC64K 12 IC8087 IC91M10 IC9256K10 IC V20 ICV30 10MHz XT M:Board.OK RAM Baby 286 M:Board. 12MHz_ OK Baby 286 M Board.20MHz·OK Baby 286 MBoard.all-in- I Baby 386 MBoard.20MHz_ 2M 149.00 545.00 945.00 495.00 3000.00 1M RAM Chip - 100nS 256K RAM Chip · 120nS 256K RAM Chip · BOnS 80287. 10MHz Co-processor 80287. 6MHz Co-processor 80287. 8MHz Co-processor 4 X 256K RAM Chips.1OOnS 64K RAM Chip - 120nS 8087-2. 8MHz Co-Processor 9 x 1MB RAM Chips - 100nS 9 x 256K RAM Chips -100nS NEC V20 Chip NEC V30 Chip - 10MHz 55.00 16.50 18.00 540.00 315.00 450.00 55.00 7.50 275.00 395.00 148.50 29.00 49.00 DISK DRIVES DD1037A D01053 DD113 7H D011 37HF 0011 57C 0D3142 003142F D05126 Disk Onve. NEC 720K . 3.51n Disk Drive. NEC 360K Disk Drive. Mitsubishi. 720K 1.44M Disk Drive. Mitsub1sh1 720K 1.44M ~ 5.25HFrame Disk Dnve. NEC 1.2MB Hard 00. NEC 42MB. 28mS . 3.5" Hard DO. NEC 42MB. 2BmS . 5.25" Frame Haid Disk Dnve. NEC 20MB 199.00 175.00 199.00 235.00 199.00 745.00 775.00 399.00 SOFTWARE ~~~&3° gg~ W,f!C~~~ersK)n SWPAINT New! Porta Disk NEC quality for not much more than unknown brands' 003142 43 .3MB, 3.5 inch or 5.25 inch Average seek time 28ms $ 745 CHIPS • Fully compatible with WO -1 006-MM1 card . • Controls 2 ST506 MFM hard disk drives. • Hard disk drives can be up to 16 heads and 1048 cylinders. • Interleave 1:1. ful l track buffer. • Bus speed - 16 MHz. • Data transfer rate - 440 KB ·seconds . • Built-in CRC/ECC . • Card size - 21 .5 x 10.7cm NEC Hard Drives OO3142F MOTHERBOARDS • WD-1006-MM1 chip set. $195 • Will mount in 3.5 inch drive space or 5.25 inch space with OO3142F 003142 M81600 MB286120K MB28620 MB286AIO MB386202M CAT 2300W • Transfer rate 250KBits/Sec • Size: 130mm(L) x 25.4mm(W) x 101.6mm(M) • Formatted capacity 43.3MB • Non-operating shock: 40G • Size: 41 .3mm(H) x 101.Smm(W) x 146mm(D) NEC 720K 3.5 inch half height micro-floppy drive. $249 AT/386 Hard disk controller This drive is ideal for compact and low power equipment. Utility CCS Pa1nlshow SWS L 1 EleclrteaL Electronic . Plumbi ng SWSL2 Home Design & Furrnsh,ngs SWS L3 SWWM Flow C hart Symbols ordmag1c. W ordprocess1ng 159.00 79.00 49.00 69.00 69.00 69.00 99.00 ACCESSORIES AC 5400 ACOM ACJOY ACLM ACLMA ACL MB ACM 2 ACMA ACMA I ACMG 1-l EGA Colour Mon11or Designer Mouse 1290 DPI , Joystick Log11ech Mouse Log1tech Mouse - P a1nHt log1lech Bus tv\ouse -Paint NEC Mult1sync II Monitor Mon11or TTL Amber Mouse M.it M oni101 TTL Grt..-en 695.00 99 00 30.00 120 00 13000 140 00 1049 00 19900 ; 50 19900 CONSUMABLES C00 1200 C00360 C00B 1200 C00 8 36 0 COM 0 :'20 D1ske ne 00• at 10 I 2M 0 1ske ne bo • ol 10 360K 0 1skene 1 2M Bulk P ack 0 1skene 360K Bulk P ack M icro Disk Bo x of 10 :'20K l.AGC9M L AH DD!C L AHD!1 1J l ANl JI I I A() l Se n.JI C able.2 M 025F 02 5M Serial Cable.2M 09F 0 2 5 M Prin ter C able 3M 25 Pin Printer Cable 5M 25 p 1P f\(l, 1pro1 N1JII MCX1t•rl' ~ IJ-•'.--lt·• --;, .,,. 11 (), •" 1/0 CARDS VGA Card. 800 x 600 VGA Card. 1024 x 768 Turbo Colour Graphics Cd Colour Graphics Mono Card EGA Card . W Hercules Mode Turbo.Mono Printer Card KB1 01 KBCAT Keyboard. 101 Keys XT AT 101 Key Keyboard + Mouse 9 ;5 9 ;5 9 ;5 9 ;5 9 ;5 9 ;5 9 95 '2 00 1 9 ;5 990 11 5 00 19900 DISK CONTROLLER CARDS DC1004A DC1220 OC1240 OC2200 OC2300 OC2300W DC2310 DC2340 Floppy Disk Card . 4 Ports 1.2M 360K.720K 1.44M FDC Disk Cont. 21n .2E x.or 41n Hard Disk Controller - XT Hard Disk Controller • AT Hard Disk Controller Card • ·Ar 1:1 Interleave Hard Floppy Disk Controller Card 1 :1 lnl - Ar 2HDD 4FDD Controller · AT 55 00 9900 130 00 14 500 199 00 22 5 OC 2J9 QC 299 oc POWER SUPPLIES PS9150CB PS9150S PS9180 PS91.BOL PS9200 PSCAP 150W PSU . Circu;t Board I SOW Swnching PSU · XT 180W Swirch PSU · Baby AT 180W PSU. Baby AT. L Type 220W Sw1lch1ng PSU . AT 1SOW PSU Cap. 220uF 200V CASES CAAPC4B CAAT CAA TB CAEX3H CAEX5 CAEX52 CAMCASE CA TB CA TBP NEC APC IV Mlg._~racket Case. hinged AT Case. hinged. Baby AT 3.5 HOD Ext. Case. Cable 5.25 FD Exl. Case. Cable 5.25 2FD Ext.Case . Cable 5.25Case for 3 .50nve Baby Tewer Case AT Baby Tower Case • PSU CATOWER6 Case. Tower for 6 Device s INTERFACE CARDS 9 ;5 495 00 795.00 99 00 11 5 00 24 9.00 11500 KEYBOARDS 3.00 1 50 35 00 15 ; 5 15 ;5 15 00 19 20 129.00 27 00 55 00 7900 10600 ; 5 00 75 00 125 00 245 00 299 00 599 00 25 00 VIDEO CARDS VCOBOO VC1024 VC 1623 VC 1625 VC1629C VC 1635 CATOWER6PTower Case Tor 6D . • PSU CAXT Case. hinged XT ,:oo Adap1or 09F to 0 25M Adap1or 09M !O 0 25F Floppy Disk Cable G t!nd~r Changer D25F 0 25F G ender Ct 1<1nger C25M 0 25M Gender Ct1anger 09F 09 F Gender Ct1c1nger 09M 09 M H, ud Disk Cclblf! 20 W,ly H, m1 0 1~" Cc 1blt! 1-l Wdv Multi 1:0 Card - XT only Parallel Printer Ca1d Serial RS232 Card .XT only Serial RS232 X 2. XT only I O Plus Card · XT Only Serial Parallel Card - XT 2 Serial. 2 Parallel. AT 1xP. 1(2) x S. 1 x G. - AT Mulli-Serial Card. 4P -AT Multi 1:0 . 4S. 1P. 1G Multi -Ser ial Card. BP -AT Chip Sal for IC1010 25.00 LEADS & ADAPTORS 1. A2MSPC L.A2MSPC<; LAJMPC 1.A5MPC I A9F25M LA9M25F LAFOOC LAGC25 f LAGC25M LAGC9F 101005 101009 101010 I010102P 101014 1022 10 102220 102230 102240 102250 102280 IOCHIP IF024 IF045 48 Line I O Card Serial RS-422 Adap10, IF046 IF0 54 Industrial I O Card Universal W ire-wrap Card IF055 IF286S IF488 IFAOOA 12 IFAOOA14 IF CLOCK IFEPROM Dual Serial RS-422 Card 80286 Speed -up Card IEEE 488 ln1erlace Card A-D 0 -ACo nv. 1 Channel A-0 0 -A Conv. 2 Channel Clock Card XT EPROM Wn1er Card 85 oc 12 J QC 1-1 5 QC 1J5 0C 195 0C 2 6C 35 oc 155 OC 125 oc 99 oc 11 5 0C 125 00 25 QC 1J9'0C 299 00 299 00 492 00 95 0C 11 QCG 135 00 445 00 12500 195 00 495 00 399 00 199 00 44 9 00 50 00 245 00 RAM CARDS RC1015 RAM Card . OK RAM . XT only RC2000 2MB EM S Memory Cd. OK RAM RC2000 EE A 2MB RAM Cd.OK LIM EEMS AT RC2(J()() EE X 2MB RAM Cd OK LIM EEMS XT RC2350 3 5MB M Func1Cd OK RAM 2 5MB RAMCd 1S l P AT RC 2500 ·3 5MB RAM Co OK RAM AT RC1'l50 9900 19900 295 00 295 00 495 00 22 6 00 22600 The Amazing "All in One" AT .Motherboard '. That's right - a comple~ 12MHz AT {minus video card) built right onto a "baby-sized' ,m o ~ . only 8.5" x 13". Not OJlly do you get superior perfonnance (with aD '. mel'llOf)' and disk running at processor speed), but you save a fortune. 0 ' 0lher features include · • 12MHz-zerD'wail,stale perfoonance equivalent to 16MHzonmostATs ~ .' • DISC . :· (dynam . ic 110 . controO provides superior compali!)i!ity wittl addcon ,· ·s . ·p e . e · d ; cards . ~~~:::=:;to ~ expal'ISii>ncards. I the . 256K ~ B cliips. i :• TWoserialpo11sandone;parallelport • on-board 2MB Universal Expanded/Extended Memory Card XT/AT Compatible • On-board floppy'drive controDer suits both Motherboard • And for an introductory period, the price is CAT MB1600 Need more memory for your "power" applications. These state-of-the-art memory cards suit all IBM PC/ XT/ATs and compatibles and provide complete compatibility with : • Expanded memory (EMS. EEMS and LIM 4.0 specification expanded memory • Extended memory recuired by windowing operations. They come complete with software drivers fo r all the above. plus print buffering. disk spooling and RAM disks . The 16 bit interface on the AT version provides higher speed than other cards . Call for highly competitive memory pricing. Price 1nc . software driv ers. with no RAM fitted. only $295.00 1 1 - ~ ~ - - ~ -- -- - - - , backup provided. CAT RC2000 EEA (suit AT) CAT RC2000EEX (suit XT) • 51/4' and 31/.!drivesv . :• "Awan:r B'9S with built-in se!Qp. 7 channel OMA and 16 lellel intenuplS • Heallime clock. and off-board battety j 1 ! Australia's lowest price on these brilliant XT motherboards. Now you can boost performance of your PC over 2.5 times without spending a fortune. V20 CPU running at 4.77110MHz, install up to 640K RAM on the motherboard. Size only 8 ½" x 9". But stocks are limited at this price so order early. Note: these boards have NO RAM FITTED. only $149.00 Floppy Controllers that do everything! Dual Adaptor 1.2MB/260K/720K /1.44MB - 3.5", 51/4" Universal Wirewrap card $ 495 4 way drive adaptor - all formats supported XT Hard Disk/floppy disc controllers CAT DC1240 Hard disk controller/suit PC/ XT CAT DC2200 This high performance floppy controller suits all IBM PC/XT/AT/386 and compatibles. It can interface up to 4 floppy disk drives configured as 2 internal and 2 external or 4 internal drives. any combination of either 5 1/4 .. (360K or 1 .2MB) or 3S (720K or 1.44MB) can be fitted. only $130.00 AT/386 Hard disk/floppy disk controller This high performance hard disk I controller for IBM PC/XT. fits in a half sized slot. It uses highly reliable Dig ital Phase Lock Loop circuitry. CRC and ECC functions to ensure data integrity. Built-in format and parameter settings in ROM. Suppcrts 2 x ST506 type drives which can be of different types. only $145.00 I XT AT 386 compatible CAT IF054 ELECTRONIC SOWTIONS _ Perfect lor the engineer or CAT DC1220 ,,x penmenter. this wirewrap card orov,des buttered inputs and outputs to ;;ro lPCI you, PC Superb plated "irougl1 wirewrap area . • Works w1lh all PCs . XT AT 386 with .1 12MHz busses • lluilt ,n dala bus . address bus. I 0 1irH• butter circuits • I l82'i l,emale connec tor • .moo >101., wire wrap area only $125.00 This adaptor is fully compatible wi!h , IBM PC/XT/AT/386 and compatibles and provides control for: • 1 or 2 drives • Any combination of 1.2MB and 360KB (5 114") or 720KB/ 1.44MB 3.5 drives Requires DOS 3.0 or later. Cables for both 5 1 4" and 3S are provided. DOS 3.3 or later is required for control of 1.44M B drives. The price has been reduced while cu rrent stocks last' only $99.00 Suits IBM/PC/AT. Supports up to two hard disks while controlling up to 4 floppy disks. These may be either 2 internal/2 external or 4 internal drives. Floppies may be either 5.25 .. (360K or 1.2MB) or 3S (720K or 1.44MB). only $299.00 Box 426 Gladesville 2111 Phone (02) 427 4422 Fax (02) 427 2542 We accept: Bankcard. Mastercard & VISA. mail orders ou r spec1alty. All prices include sales tax Note: Products may vary ,n appearance from those pictured . In all cases they will perform to the same or a better standard. • All products carry a 14 day money back guarantee (software accepted ) • All products carry a fu ll 3 month warranty • All cards come with iull documentation Compact Ultrasonic Car Burglar Alarm This compact ultrasonic car alarm is based on a proven commercial unit. It's extremely sensitive and will respond instantly to glass breakage, a door opening or movement inside the vehicle. By GREG SWAIN Ultrasonic car burglar alarms have one big advantage when compared to other alarm systems they're dead easy to install. All you have to do is position the two transducers next to the front windscreen pillars, plug the leads into the control unit, and hook up power and a siren. 58 SILICON CHIP There's no need to muck about running leads to door switches as with other burglar alarms. But ultrasonic alarms can have their drawbacks too. Many are prone to false triggering, either because they are temperature sensitive, or are prone to interference, or are sensitive to supply line glit- ches. Given these problems, it's no wonder that some alarms false trigger with monotonous regularity. This unit suffers no such problems. It's based mainly on discrete transistors and has been used for several years in commercial car alarm systems. So it's fair to say that this is one ultrasonic car alarm that has been thoroughly debugged. It's also much more compact than any previously described ultrasonic alarm. The printed circuit board, which holds all the parts, measures just 112 x 43mm and fits neatly into a moulded plastic case. The unit is compact enough to mount under the dashboard of any car. Recently, Oatley Electronics was THE TRANSMITTER TRANSDUCER PRODUCES A TONE WHICH HAS CONSTANT AMPLITUDE AND FREQUENCY +v PARTS LIST TIME TRANSMITTER ((~TSDUF 40kHz 1n1 -,V S T l ~ L M~Ji~~NT ENVIRONMENT +V -V MOVEMENT PRODUCES AMPLITUDE AND PHASE CHANGE IN THE RECEIVED SIGNAL Fig.1: the transmitter transducer produces a steady 40kHz signal which is picked up by the receiver. If movement occurs, the reflected signal undergoes phase and amplitude changes and the alarm triggers. able to purchase a large quantity of surplus parts for these ultrasonic alarms from the manufacturer, including PCBs, cases and transducers. Oatley Electronics has simply added a few on-board components and is offering the complete kit (with transducers) for just $42.95. That's really good value. To make up the kit, all you have to do is install the parts on the PCB and secure the board inside the case. By combining the unit with a UHF remote control switch, you will end up with a really effective burglar alarm for far less money than equivalent commercial units. The two transducers are even supplied prewired and are fitted with protective rubber " boots" and spring clips to allow easy attachment to the windscreen trim. The end of each transducer cable is fitted with a small locking connector and these plug into matching connectors on the PCB. Options You can either use this unit as an add-on ultrasonic sensor for an existing alarm or as a complete selfcontained alarm in its own right. If used to trigger an existing alarm, there's no need to worry about turning the ultrasonic sensor on or off. The main alarm system is simply turned on and off as before using a keyring transmitter or a hidden switch coupled with exit and entry delays. For use as a self-contained alarm, the unit must be combined with a remote control switch. This is because the ultrasonic circuit has no exit or entry delays; it must be turned on and off from outside the vehicle. Either the UHF remote control sold by Oatley Electronics or the SILICON CHIP UHF remote control can be used for this job. We'll have more to say about this later on. Finally, it's also possible to add bonnet and boot protection. Our circuit shows how this can be done using spring loaded pin switches wired to a single control line. Crystal control All ultrasonic movement detectors include an oscillator circuit which drives an ultrasonic transducer element (usually at 40kHz). Many designs use a free-running RC oscillator but this design uses a crystal locked oscillator to eliminate the need for oscillator frequency adjustment during construction. There's only one control on this unit that has to be adjusted and that's the sensitivity control. A crystal oscillator has far better stability than a free-running oscillator. In practice, this means that the unit can be set for far greater sensitivity without false triggering problems. On the other hand, ultrasonic alarms with free-running oscil- 1 PCB (available from Oatley Electronics) 1 plastic case 1 pair of transducers (pre-wired with connectors) 2 PC-mounting connectors 1 miniature SPOT relay 1 40kHz crystal 1 800mm length of 3-way cable 1 plastic cable tie Semiconductors 1 4069 hex inverter IC (IC1) 6 BC548A NPN transistors (01-06) 2 1 N4004 silicon diodes (04, D5) 1 1 N4148 silicon diode (03) 2 OA90 germanium diodes (01, D2) 1 3mm red LED Capacitors 1 4 7 µ,F 16VW electrolytic 1 22µ,F 16VW RBLL electrolytic 1 1 0µ,F 16VW electrolytic 2 4. 7 µ,F 16VW electrolytics 7 0. 1µ,F monolithics 2 .001 µ,F disc ceramics 1 220pF disc ceramic Resistors (0 .25W, 1 2.2MQ 1 5 1MQ 3 3 220k0 1 2 120k0 1 1 47k0 2 1 15k0 1 5 10k0 2 1 1 MO trimpot 5%) 4.7k0 2.2kQ 4 700 3300 2200 1000 470 lators frequently false trigger due to amplitude and phase changes in the oscillator output as the temperature changes. How it works An ultrasonic movement detector works by detecting amplitude variations in a single tone which is beyond the range of human hearing. In this design, the transmitter produces a continuous tone at 40kHz and this signal fills the area inside the car due to reflections from the inside surfaces. Some of this reflected 40kHz signal is picked up by the receiver transducer for processing by the ]UL Y 1989 59 The ultrasonic transducers are supplied pre-wired and fitted with rubber "boots" and spring clips. The unit is small enough to mount under the dashboard of any car. receiver circuit. As shown in Fig.1, a steady tone is picked up by the receiver if there is no movement inside the car. However, if movement does occur, the received signal undergoes amplitude and phase changes and these trigger the alarm circuit. Fig.2 shows the circuit details. There are six transistors in all, together with a single 4069 hex inverter IC. The circuit works like this: oscillator ICl b-ICld provides the 40kHz drive signal to the transmitter transducer which generates the ultrasonic output signal. This signal is picked up by the receiver transducer, amplified by tran- sistors Ql and QZ and then detected by Dl and DZ. If there is no movement, a steady DC signal appears at the output of the detector and no signal is applied to the base of Q3. Conversely, if movement does occur, the detector output fluctuates rapidly and these amplitude variations are amplified by Q3 and Q4. Q4 then drives Q5 which pulls pin 9 of ICla low. Thus, the output (pin 8) of ICla switches high and turns on Q6 to activate the relay and the external siren circuit. Let's now look at the circuit in more detail. The transmitter circuit employs three inverters from the Where to buy the parts Parts for this project are available from Oatley Electronics, 5 Lansdowne Pde (PO Box 89), Oatley, NSW 2223. Telephone (02) 579 4985 . Prices are as follows (mail orders add $2 .50 p&p): Complete kit (does not include siren or pin switches) ... ... ....... .. $42.95 PCB plus on-board parts only ...... ...... .... ........ .... .. ...... .. ... ... .. . $25.90 Pre-wired transducers with connectors (pair) .... ..... .... .. ...... ..... $1 9. 00 Note: copyright of the PCB artwork associated with this project is retained by Oatley Electronics. 60 SILICON CHIP 4069 hex inverter package. ICld is biased in the linear mode by the lMO feedback resistor and its output also biases IClc in the linear mode. ICld and IClc thus form a linear amplifier with an overall phase shift of 360°. A 40kHz crystal is included in the feedback path between the input and the output and so the circuit oscillates at the crystal's resonant frequency [ie, at 40kHz). Note that one side of the crystal is coupled into a voltage divider consisting of two 220k0 resistors. This has been done to prevent excessive drive voltages from being applied to the crystal. ICl b buffers the output from the oscillator (pin 4 of IClc) and drives the 40kHz transmitter. Receiver circuit The reflected signal from the transmitter is picked up by the receiver transducer and applied to the base of transistor Ql via a .00lµF capacitor. Ql is a common emitter amplifier stage with a voltage gain of approximately 100. Its output is coupled via another .00lµF capacitor to the base of QZ Fig.2 (right): reflected signals from the transmitter are picked up by the receiver, amplified by Qt and Q2, and detected by D1 and D2. Q3 and Q4 amplify the detector output and drive timer trigger stage Q5. which operates with a gain of about 40. Q2's output is coupled via a O. lµF capacitor to a "floating" detector stage consisting of diodes Dl and D2 and associated components. The advantage of this type of detector is that it produces very little output due to phase changes or slow changes in the amplitude of the 40kHz signal. This stops the unit from giving false alarms due to air turbulance generated inside the vehicle by temperature changes. Instead, the detector responds only to rapid amplitude changes in the received signal. And that's precisely what happens if there is movement inside the vehicle, or there is glass breakage etc. The output from the detector is coupled via sensitivity control VRl, a 4. 7µF capacitor and a low-pass filter stage (47k0 and O.lµF) to two more common emitter amplifier stages consisting of Q3 and Q4. These two stages operate with gains of 40 and 100 respectively. The low-pass filter stage provides further insurance against false triggering by rolling off the detector's output for frequencies above 30Hz. The amplified detector output appears at Q4's collector and is coupled to timer trigger stage Q5 via a 4.7µF capacitor. When Q5's base voltage exceeds 0.6V, its collector voltage goes low and quickly charges the 22µF timing capacitor via the associated 2.2k0 resistor. ICla's pin 8 output then switches high and turns on Q6 and the relay to sound the siren (or to trigger another alarm circuit). When the relay is energised, its normally closed contacts open and Q4's 470 emitter resistor loses its ground connection. Q4 and Q5 now turn off and the 22µF timing capacitor begins discharging via the parallel 2.2MO resistor. Thus, the 22µF capacitor and 2.2MO resistor determine the time taken for the circuit to reset. After about 40 seconds, pin 8 of CF-:. ~ a: <( ...J ~ 0 1- u w ljj Cl 1- zw ~ w > 0 ~ (.) z > + 0 "'a: <( _H•· Y ~ = + Wlv......-4........_H•· = ~ ::::> "" "" ~f-,•• ~ :,; = "' = I• ~ = -" + !;;H•· .,_-w,.,---1,. = "" JULY 1989 61 This larger-than-life size photo shows how the parts are mounted on the PCB. Note that all the transistors face the same way except for Q5 which faces in the opposite direction. The two connectors at left accept the transducer plugs. ICla switches low again, Q6 and the relay switch off, and the siren · stops.At the same time, the ground connection for Q4's emitter resistor is restored and so the circuit is reset, ready to detect any further movement. LED 1 is there to provide visual indication that the circuit is working. It lights whenever Q6 turns on and activates the relay. D4 protects Q6 from spike voltages when the relay turns off. Protection for the bonnet and boot is- provided by the normally open spring loaded pin switches. If either of these closes, Q3's collector is momentarily pulled to ground via a O.lJ.lF capacitor and this instantly triggers the alarm. The alarm is disarmed whenever the DISABLE input is held high. When this happens, pin 9 of ICla is pulled high via D3 and the 4700 resistor. Thus, pin 8 of ICla will be low and Q6 and the relay will be off. In practice, the DISABLE input is simply linked to the DISABLE ouput of the SILICON CHIP UHF Remote Alarm Switch Receiver (described in March 1988) or to the emitter of 62 SILICON CHIP transistor Q5 in the Oatley Electronics UHF remote control receiver. Power for the circuit is derived directly from the car's battery via diode D5. D5 is there to protect the circuit against possible reverse polarity connection to the battery. Construction The copper pads on the PCB are all quite small so you will need a soldering iron with a fine tip to successfully build this project. Apart from that, construction is straightforward but watch out for solder bridges between adjacent pads on the board. Fig.3 shows how all the parts are mounted on the PCB. Install the two wire links first, followed by the resistors and the diodes. Be sure to use the correct diode at each loca tion. You must use the OA90s (the ones in the clear bodies) for Dl and D2, while D3 and D4 are the 1N4004s. The monolithic, ceramic and electrolytic capacitors can all be installed next. Push all the parts down onto the PCB as far as they will go before soldering the leads 0 and make sure that the electros are all installed the right way around. Next, you can install the six transistors, the IC and the crystal. Note that all the transistors face in the same direction except for Q5, which faces the opposite way. Pin 1 of the IC is adjacent to a small dot or notch in the plastic body. It doesn't matter which way around you install the crystal. Before mounting this part, bend its leads at right angles where they emerge from the case. This will allow the crystal to lie flat against the PCB as shown in one of the photos. The PCB assembly can now be completed by installing the two transducer connectors, the trimpot, the relay and the LED. Take care with the orientation of the LED its anode lead is the longer of the two. Don't worry about the off-board components associated with the DISABLE input and the pin switches for the time being. These parts are "add-ons" to the original circuit and have no effect on the basic operation. They can be installed after the circuit has been tested. Fig.3: here's how to wire the unit as a self-contained alarm. If you intend using the unit to trigger an existing alarm, the 2.2MO timing resistor should he reduced to lOkO and the horn siren delected. OPTIONAL BONNET ANO BOOT PIN SWITCHES .,. RESISTORS □ □ □ □ □ □ □ □ □ □ □ □ □ □ No. 1 5 3 2 1 1 5 1 3 1 1 2 1 2 Value 2 .2MO 1MO 220k0 120k0 47k0 15k0 1 OkO 4 .7k0 2 .2k0 4700 3300 2200 1000 47n Now go back over your work and carefully inspect the PCB assembly. Check that all the parts are in their correct locations and are correctly oriented. You should also check the underside of the board for solder bridges and missed solder joints. When you are satisfied that everything is correct, the 3-wire cable can be wired to the PCB. Connect the black lead to the earth track (between the two connectors), the red lead to the + 12V rail, and the yellow lead to the output terminal. Testing To test the unit, set the sensitivity 4-Band Code red red green gold brown black green gold red red yellow gold brown red yellow gold yellow violet orange gold brown green orange gold brown black orange gold yellow violet red gold red red red gold yellow violet brown gold orange orange brown gold red red brown gold brown black brown gold yellow violet black gold 5-Band Code red red black yellow brown brown black black yellow brown red red black orange brown brown red black orange brown yellow violet black red brown brown green black red brown brown black black red brown yellow violet black brown brown red red black brown brown yellow violet black black brown orange orange black black brown red red black black brown brown black black black brown yellow violet black gold brown control to maximum (fully clockwise) and solder a 10k0 resistor across the 2.2MO timing resistor on the copper side of the board. This will reduce the timing period to about 0.2 seconds so that you don't have to wait for the unit to reset each time it is triggered during testing. You don't have to hook up the external siren at this stage - the LED and the relay will provide sufficient indication that the unit is working. Now plug the transmitter (SQ40T} and receiver [SQ-40R} transducers into the on-board connectors [careful: don't mix them up) and connect up a 12V power supp- CAPACITORS □ □ □ No. 7 2 1 Value 0 .1µ,F .00 1µ,F 2 20 pF IEC EIA 100n 104M 1n 102K 220p 221K ly. The unit should now be operational; ie, the LED should light and the relay should operate whenever movement occurs. In practice, you should find that the unit is quite sensitive. With the transducers set up about 30cm apart on a workbench, we found that our unit would trigger reliably JULY 1989 63 Above: the ultrasonic transducers simply plug into connectors at one end of the case. The receiver socket is the one on the left. Left: don't confuse the two transducers. The transmitter is labelled SQ-40T while the receiver is labelled SQ- 40R. at distances up to 7 metres. So, in the confines of a car, the unit will have tons of sensitivity. What! - it doesn't work? If the unit fails to operate as expected, look for incorrect component placement on the PCB and for shorts on the copper side. Are all the resistor values correct? Are the electrolytic capacitors correctly oriented? Is Q5 the right way around? If these checks fail to reveal anything, you can quickly determine which half of the circuit is not operating by momentarily shorting the collector of Q3 to ground (unplug the transducers first). If the LED now lights and the relay operates, then the fault lies before Q3 or in the transmitter. Conversely, if nothing happens, then the fault lies after Q3. The relay driver circuit can be easily checked by momentarily shorting pin 9 of ICla to ground. Similarly, you can check the circuit operation from Q5 on by momentarily shorting the 4. 7µF capacitor. A few voltage checks will also quickly reveal a faulty stage. Again, these checks are best made with the transducers unplugged. When power is applied, Ql, QZ, Q3 and Q4 should all have base-emitter voltages of about 0.65V. On the prototype, the collector voltages were + 4.6V for Ql, + 4.0V for QZ, + 4.6V for Q3 and + 4.0V for Q4. These collector voltages should be taken as a guide only, since they The transducers are best mounted adjacent to the front windscreen pillars. They can be secured by forcing the spring clips under the trim. 64 SILICON CHIP will vary according to the beta of the transistor. Installation Fig.3 shows how the unit is wired as a self-contained alarm. The offboard components can simply be soldered to the appropriate points on the top of the PCB and wrapped in insulation tape to prevent shorts. Alternatively, you can drill extra holes in the PCB and mount the parts on the board itself. The necessary wiring connections can then be made by running insulated links on the copper side of the board. A dab of Araldite can be used to secure the parts to the top of the PCB. The PCB is secured inside the case using a single self-tapping screw. Once the assembly has been completed, it can be mounted in the car under the dashboard. In many cars, you can gain access behind the dash panel by removing the loudspeaker grille and the loudspeaker. The two transducers are best installed on top of the dash adjacent to the windscreen pillars. Plug the transducer leads into the control unit, then connect up the siren and the supply leads. The + 12V supply can be derived from the fuse panel. Finally, if you intend using the unit as a sensor to trigger an existing alarm, the 2.2MO timing resistor should be reduced to lOkO. The 12V siren and the off-board components are deleted and the yellow output lead is simply connected to one of the alarm inputs.~ W~JOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR C ~ ~:r~-------------------------------------iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii-:7, More Goodies from Woodies - with Extra Value Bonus on every ~ fi: EPROM Programmer and Eraser purchased this month. ~ § (Don't forget to ask for yours!) ~ ~ C ~ ~ PC CARD PROM PROGRAMMERS LEP-101 4 way for IBM-PC/XT/AT Programs EPROMs 2716/A to 27512/A including NMOS and CMOS types. Also EEPROMs 2804 to 58064. Includes bonus 5 pieces 27C64-200 valued 11/ S49.00 Tax Free$ 226.00 Tax Paid $ 262.00 STAND ALONE UNITS PROMPRO-BX Advanced Universal Programmer Programs EE/EPROMs up to 1 Meg and single voltage PROMs. 2 ZIF sockets, 28 and 4/J pin, for GANG/ SET programming. 512k bits RAM in either 8, 16 or 32 bit. Intelligent and Quick Pulse programming algorithms. Intel HexbMotorola Hex, ASCII/Binary and JE EC data formats. Centronics printer port to dump RAM contents. Automatic higMow byte programming for 16/ 32 bit systems. Vee and Vpp controlled by DAC in closed loop. Programs EPROMs 2516, 2716 to 27512 including CMOS and A types. Also EEPROMs 2816 and 2816A. 512k bit RAM buffer. 28 pin ZIF socket with 40 pin uP adapter option. Data formats Intel Hex, Motorola HEX, binary and hex. Builtin RS232 port. 110 to 2400 .baud selectable software and RS-232 cable. Includes bonus 30 pieces 27C64200 valued at S294.00 Tax Free $1642.00 Tax Paid $2268.00 lnt:ludes bOIHII 15 piet:es 27C64-200 nlued at S 147.00 Tax Free$ no.oo Tax Paid$ 898.00 PROFESSIONAL PC BASED UNIT HUSKY Devices supported include most popular CMOS, NMOS and HMOS EE/EPROMs as large as 2 Meg, popular CMOS EPLDs and single chip micros. Up to 4 devices may be programmed simultaneously with the same data or sequentially with different data. File download is fast and easy since the Husky uses a high speed parallel bus to the PC. PS/2 and Macintosh SE interfaces are also available. Intel Hex, Motorola Hex, ASCII Hex and Binary data files are accepted. Each of the four 32 pin ZIF sockets will accept ICs with widths from 0.3" to 0.6'. Single chip micros are also supported using an optional 40 pin GANG PROGRAMMERS LEP-12008 Low Cost 10 Way Programmer GANGPR0-8 Programs 2516, 2532 and 2564. 2716 up to 27512 including CMOS and A versions. Eleven 28 pin ZIF sockets. expansion socket. Similarly PLCC and PGA devices can be supported by additional socket adaptors. lni:ludes bonus 15 piei:es 27C64-200 valued ,t S 147.00 Tax Free S 873.60 Tax Paid $1019.00 lnt:lude, bOIHIS 30 piet:es 27C64-20fJvaluetl ,, S294.00 Tax Free $1139.00 Tax Paid $1321.00 Eight 28 pin ZIF sockets. Identifies and isolates faulty devices. Fast intelligent and Quick Pulse algorithms are used. Verifies automatical~· at 3 voltage levels, 5.0V and 5.0V 0.25V. Intel Hex, Motorola Hex data formats. Built-in RS-232 interface. Software for PC included. Programs EPROMs up to 1 Meg. EEPROMs up to 28256. CMOS, HMOS and NMOS types. Single chip micros using an optional adaptor. Includes bonu, 45 pieces 27C64• 200 valued at S441.00 2 ZIF sockets, 20 and 24 pin. Reads and copies existing PALs. Logic compilers supported include CAST, H.E.L.P., PALASM, CUPL & ABEL. Supports devices manufactured by Altera, AMO, ATMEL, Cypress, Fairchild, Harris (with optional adaptor), Lattice, MMI, National, Panatech, Signetics, Sprague, Texas Instruments and lni:ludes bonus 30 piet:es PAL16LBANC valued at S 193.50 Tax Free $1944.00 Tax Paid $2268.00 Tax Free $1642.00 Tax Paid $2268.00 VTT. EPROM ERASERS QUV-TBIZ ULTRALrrE Ideal high performance UV eraser suited for production or engineer's applications. Erase time is approx 15 minutes for up to 50 EPROMs. Includes bonus 5 pieces 27C64-200 valued at$ 49.00 Tax Free$ 269.00 Tax Paid $ 314.00 QUV•TB/T Erases 30 EPROMs in 10 minutes or 15 EPROMs in 5 min. Accepts PCB 8' x5' x 1·. Erases 15 EPROMs in 20 • 30 minutes. Accepts PCB 8" x 5' slide out tray. Includes bonus 2 pieces 27C64-200valued at S 19.60 Includes bonus 2 pieces.27C64-200 valued at S 19.60 Tax Free $ 192.00 Tax Paid$ 224.00 Tax Free $ 150.00 Tax Paid$ 175.00 LER-121 Erases nine 24 pin EPROMs. Includes bonus 2 pieces 27C64-200 valued at$ 19.60 Tax Free$ 81.00 Tax Paid $ 94.00 GEOFF WOOD ELECTRONICS PTY LTD 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 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. All prices INCLUDE sales tax. Tax exemption certificates accepted if line value exceeds $10.00. BANKCARD, MASTERCARD, VISA , CHEQUES OR CASH CHEERFULLY ACCEPTED ~ 0 a .,., a :0 (") :i:: ~ AMATEUR RADIO By GARRY CRATT, VK2YBX Build this intelligent charger for 12V gel batteries Do you use 12V gel cells to power your transceiver or other equipment? If so, you need to know the best way to charge them so that they last as long as possible. The "intelligent charger" described here does all the right things to look after the welfare of your 12V gel cells. When it comes to charging sealed lead acid batteries used in an amateur station, most operators use their standard 13.BVDC power supply. There is a big drawback to this method because, by definition, a 13.BV DC power supply puts out a constant 13.8 volts. Such a power supply may deliver a very much higher current to a discharged or partially discharged battery than is advisable. In fact, gel cell or sealed lead acid batteries are very fussy about being over-charged, even at low rates. They should not be charged SOURCE COMPENSATION 15 14 Charging current +VIN ,------6-----6-----< r + l - - - 0 1 3 VOLTAGE SENSE ....,,...--1----012 CHARGE ENABLE POWER 7 INDICATE 9 OVER-CHARGE INDICATE OVER-CHARGE B TERMINAL Fig.1: block diagram of the UC3906 IC. It controls both the output voltage and charging current to ensure optimum charging conditions. 66 SILICON CHIP at a constant current or 'trickle charged' unless the terminal voltage of the battery is monitored and the charging current is terminated immediately full charge is reached. Voltage limited charging is most suitable for this type of battery. The correct charging procedure for sealed lead acid batteries is to charge them at the optimum current, until a maximum voltage of 2.42 volts per cell is reached. This equates to a voltage of 14.52V for a "12V" battery comprising 6 cells. At this level, the charging current should drop to a level sufficient to maintain the full charge voltage of 13.68V (2.28V per cell). The "optimum" current depends on the battery temperature, its state of discharge and lastly, the battery capacity which is expressed in ampere/hours. Typically though, the recommended charging current varies from a maximum of C/5 to C/10 where C is the capacity expressed in ampere hours at the 20-hour rate. For example, a 4.5 amp/hour battery can deliver 225mA at the 20-hour rate. At C/5, the charging rate would be 900mA. At C/10, the charging rate would be 450mA. Provided sealed lead acid batteries are carefully charged and are not over-charged to the point where significant gassing occurs, they can have very long life in standby or "floating" use where they sit across a fixed power supply. They can last between 5 to 10 The parts are installed on a small PC board fitted with quick-connect lugs for the input and output terminals. It delivers a maximum charging current of 500mA. A flag heatsink must he fitted to Qt for input voltages greater than 20V. R1 0.5P. 5W + SUPPLY INPUT -i 01 1N5404 BATTERY R3 1k 5 3 16 i- R2 68k 1% 15 11 12 R4 22k IC1 UC3906 1% 13 R5 10 270k 1% R6 18k 1% .,. 14 BCE 12V GEL BATTERY CHARGER Fig.2: this circuit shows the UC3906 connected as a dual level float charger. It's pin 16 output controls PNP power transistor Qt which in turn handles the charging current. years. However, designing a charger for such a standby application is not an easy task, at least until recently. Fortunately, there is now an "intelligent" battery charging chip available, which has been designed specifically for this purpose by Unitrode Corporation of the USA. The UC2906 and UC3906 battery charger controllers contain all the necessary circuitry to optimally control the charge and hold cycle for sealed lead acid batteries. These integrated circuits monitor and control both the output voltage and current of the charger through three separate charge states: a high current bulk charge state, a controlled over charge, and a precision float charge or standby state. Optimum charging conditions are maintained over an extended temperature range with an internal reference that tracks the nominal temperature characteristics of the lead acid cell. Separate limit amplifiers regulate the output voltage and current levels in the charger by controlling the onboard driver. The driver will supply up to 25mA of base drive to an external power transistor. Voltage and current comparators are used to sense the battery condition and provide inputs to the charge state logic. In addition, a charge enable comparator with a trickle bias output can be used to obtain a low current turn-on mode for the charger. This feature prevents high current charging during abnormal conditions such as a shorted battery cell. Other features include a supply under-voltage sense circuit with a logic output to indicate when input JULY 1989 67 r------------._ AMATEUR RADIO; Hobbyists communicating world wide using state-of-the-art electronics. I I I I Are you into computers? ; Like to access BBS around 1 the world by radio? I Interested in different forms• of digital communication - AMTOR - PACKET? WHY NOT BECOME A RADIO AMATEUR? Want to know more? I Join the WIA - the oldest and most experienced radio society in the world - always at the forefront of radio communications for hobbyists. Receive AMATEUR RADIO, the monthly magazine for members of the WIA, full of news of DX, clubs, satellites, technical articles and lots more. • • • • • • Other WIA services include: A world wide QSL card service Weekly news broadcasts Classes for all grades of amateur licences Correspondence lessons available Meetings, contests, field days Representation for radio amateurs at Government level STATE 2 l STATE 3 I IT !OCT ,..L, }-vT IMAX STATE 1 : BULK CHARGE STATE 2 : OVER•CHARGE STATE 3 : FLOAT CHARGE CHARGER OUTPUT CURRENT Fig.3: the circuit starts off in state 1 (bullc charge) and then switches to state 2 (over-charge) and finally to state 3 (float charge). power is present. In addition, the over-charge state of the charger can be externally monitored and terminated using the over-charge indicate output and the over-charge terminate input. Fig.1 shows the block diagram of the UC3906. It comes in a standard 16-pin dual inline plastic package. Maximum input voltage is 40 volts DC. A practical circuit Fig.2 shows the UC3906 connected as a dual level float charger. CHARGE VOLTAGE ----::---.---:svoc O ~-----:F,-;;;;~V31 -r--------:---,--·:~---------, G IT Registered address: 3/105 Hawthom Road Caulfield North, 3161 Please send aWIA information package to: NAME: ........................................................... . ADDRESS: ..................................................... . STATE LEVEL OUTPUT oc INDICATE OUTPUT oc TERMINATE INPUT (C/S OUT) ~~] __ _ I OFF ................................... POSTCODE ............... .. L-------------.1 E001qii I ""~---- i - SILICON CHIP Ail high currents are handled by the external PNP pass transistor Ql which is a readily available plastic pack MJE2955. This circuit uses the trickle bias output at pin 11 and the charge enable comparator at pin 13 to give the charger a low current turn-on mode. The output current of the charger is limited to a low level until the battery reaches a specified voltage, preventing high current charging if a battery cell happens to be shorted. Of course, if you did have a battery with a shorted cell, you would have to discard it. Fig.3 shows the various charge states of the circuit. At switch-on, the charger goes into state 1, the high rate bulk charge state. In this state, once the enable threshold has been exceeded, the charger will supply a peak current that is determined by the 250mV offset of the current limit amplifier (monitoring between pins 5 and 4) and the sensing resistor Rl. Our circuit shows Rl with a value of 0.50 so the peak current value will be 500 milliamps. To guarantee full recharge of the battery, the charger's voltage loop has an elevated reguhiting level _J _______________ _ INPUT SUPPLY VOLTAGE CHARGE CURRENT P.O. BOX300 CAULFIELD SOUTH VICTORIA 3162 68 y STATE 1 Learn more about the WIA and Amateur Radio Forward this coupon, or write to: WIA EXECUTIVE OFFICE - - v oc - -v 12 - -v L r- - v 31 ~ STATE 1 .. 1. I i ~--.....,_J-_-STATE 2 I• STATE 3 • I. STATE 1 Fig.4: this diagram shows a charge and discharge cycle for a dual level float charger. Once the battery is charged, it is maintained at a precise float voltage (Vf). RESISTORS D D D D D D No. 1 1 1 1 1 1 Value 270k0 68k0 22k0 18k0 1k0 0.50 SW 4-Band Code not applicable pot applicable not applicable not applicable brown black red gold not applicable 5-Band Code red violet black orange black blue grey black red black red red black red black brown grey black red black brown black black brown brown not applicable Fig.5 (above): parts layout for the PC board. Fig.6 at right shows the actual size PC pattern. (Voc) during state 1 and state 2. When the battery voltage reaches 95% of Voc, the charger enters the over-charge state, state 2. The charger stays in this state until the "over-charge terminate" pin goes high. The charger uses the current sense amplifier to generate this signal by sensing when the charge current has tapered to a specified level, Ioct. So pin 1 is connected to pin 8. As an alternative, the over·charge terminate point could have been controlled by an external source, such as a timer, by using the "over-charge indicate" signal at pin 9. If a load is applied to the batte'ry and begins to discharge it, the charger will contribute its full output to the load. If the battery drops 10% below the float level, the charger will reset itself to state 1, the bulk charge condition. When the load is removed, a full charge cycle will follow. A graphical representation of a charge and discharge cycle of the dual level float charger is shown in Fig.4. When the charger is in the float state, the battery is maintained at a precise float voltage, Vf. The accuracy of this float state will maximise the standby life of the battery, whilst the bulk charge and over charge states guarantee rapid and full recharge. All of the voltage thresholds on the UC3906 are derived from the internal reference. This reference has a temperature coefficient that tracks the temperature characteristic of the optimum charge and hold levels for sealed lead acid batteries. This further guarantees that proper charging occurs, even at temperature extremes. External supply Because the series pass transistor, Ql, is a PNP type, the supply input does not need to be very much PARTS LIST 1 PCB, code SC 11107891, 77 x 41mm 4 quick connector lugs Semiconductors 1 UC3906 battery charger controller (IC1) 1 MJE2955 PNP transistor (01) 1 1N5404 power diode (D1) Capacitors 1 1 OOpF ceramic Resistors (¼W unless stated) 1 270k0 1 % 1 18k0 1 % 1 68k0 1 % 1 1kO 5 % 1 22k0 1% 1 0 .50 5W higher than the maximum output voltage of the charger. This means that the input voltage can range upwards from 15V DC, with 18-20V being ideal. The higher the input voltage to the circuit, the higher the dissipation in Ql. For the circuit as shown, which delivers a maximum of 500mA, no heatsink is required for Ql for input voltages up to a bout 20 volts DC. For higher voltages, a flag heatsink will be required. Construction To provide a basis for experimentation, we have designed a small printed circuit board measuring 76 x 40mm (coded SC 11107891). The component layout diagram is Fig.5. Our prototype board has been fitted with quick-connect lugs for the input and output terminals but these are optional. Note that all the resistor values, with the exception of Rl and R3, should be 1 % tolerance to make sure that the design targets for over-charge voltage and float voltage are obtained. For this design, the float voltage is 13.8V and the over-charge voltage is 14.56V. The UC3906 is available from VSI Electronics Pty Ltd, PO Box 578, Crows Nest, NSW 2065. Phone (02) 439 8622. ~ JULY 1989 69 COMPUTER BITS By JENNIFER BONNITCHA* A look at video monitors Every personal computer has a video monitor but very little is written on the many different types of monitor. All monitors work in much the same way as television screens but they are driven by digital instead of analog signals. IBM's entry into personal computing in the autumn of 1981 caused more than a little excitement. Prior to the PC's development, IBM's policy was that anything connected to its machines had to be an IBM product. Keeping the inner workings of their computers secret created for IBM a seemingly unassailable monopoly. In a landmark decision, the company decided to make available all the necessary technical details on the PC. Since Big Blue's logo means business to most people, the general perception of the personal computer changed almost overnight from that of a hobby machine to that of a serious business tool. Suddenly there was an army of small entrepreneurs eager to make peripheral products for the PC. Literally hundreds, probably thousands, of companies now exist because the PC does. However, it is also true to say that the PC and its compatibles sell because these businesses exist. Perhaps the most important peripheral for the PC is the monitor, through which the PC communicates with you. The continuing development of both monitor and adaptor boards means that the picture you see is becoming more and more detailed. The TV-like screen through which your computer communicates with you is called many names: display, CRT (Cathode Ray Tube), video monitor, screen, VDT [Visual Display Terminal) or simply terminal. It forms a necessary part of your computer since it provides visual feedback as you run your programs. Typically you make a choice from a menu or enter data at appropriate locations via the keyboard. The display you see on the screen is the result of some activity on the part of the program. So, now you've decided to put your carefully saved computer dollars down on a You Beaut Turbo XL computer. The next question is: What monitor do you put on top of it? Answer: that depends. It depends on what you need your * Jennifer Bonnitcha is an independent consultant and has a wide experience of computers ranging from mainframes to personal computers and peripheral devices. She is also experienced in the use of integrated and spreadsheet software, word processing and desktop publishing. Jennifer is the founder of Business Action, a company specialising in on-site training in the use of personal computers for business applications. 70 SILICON CHIP computer to do, your personal tastes, and of course the bottom line - how much you have to spend. At one end, you could get a standard low-priced monochrome monitor suitable for your network server. At the other end, you can get 50cm or so of high-powered resolution and colour, suitable for graphics or CAD. How monitors work Monitor jargon is as daunting as any in the field, with plenty of acronyms, like MDA, CGA, EGA and VGA, and technical specifications like resolution, scan frequency and dot pitch. All video monitors function like a television set in that an electron beam is swept across and down the screen by the deflection circuitry. However, instead of having a continuous picture made up of interlaced lines, the image produced by a monitor comprises a large number of small dots in fixed position. The dots are arranged in horizontal rows (corresponding to the horizontal scan lines) and the term resolution refers to the number of points across the screen and the number of rows (or lines) up and down the screen. What it all ultimately comes down to is dots on the screen, or picture elements (pixels for short). Therefore a high-resolution monitor implies that the number of pixels is larger than in medium or low resolution monitors. Higher resolution means a more detailed image on the screen. All the specifications ultimately say are how many dots the screen has and the acronyms represent standard ways to create the dots. High resolution monitors are not confined to IBM machines. These two monitors are designed to suit the Apple Macintosh. The larger of the two is a nominal 21-inch unit with 1152 x 870 dots of resolution. Its refresh or vertical scan rate is 75Hz. Initially, video monitors used the American NTSC TV standard as the basis of their operation. This means a field frequency of 60Hz and a line (or horizontal scan) frequency of 15,750Hz. Higher resolution monitors use higher scanning frequencies so they can put more dots on the screen. The image is generated by an electron beam sweeping over the screen one line at a time while the intensity is varied. For text or graphics displays which are made up of dots all having the same brightness, the electron beam intensity is switched on and off - on for a dot, off at all other times. Each line is scanned left to right with the intensity of the beam determined by the data stored in the video RAM of the display board. In all but the simplest displays, the intensity can be varied rather than simply being on or off. At the completion of each line, the beam rapidly returns or "retraces" to the beginning of the next line. During this retrace period, the beam is turned off so that it is invisible. When the screen sweep is complete, the deflection coils around the neck of the picture tube move the electron beam back to the top left-hand corner of the screen ready to scan the next screen. So far we have described the operation of a monochrome monitor which has one single electron beam. The actual colour of the screen display is determined by the internal phosphor coating of the picture tube, giving green, amber or white. Colour monitors A colour monitor has three beams sweeping across the screen in unison. By means of a shadowmask inside the tube face, each beam is arranged to strike only its appropriate small dots of red, green and blue phosphor on the surface of the screen. So the red electron beam only excites the red dots, the blue beam excites the blue dots and the green beam the green dots. Thus you get colour and, depending on the intensity of the beam, different degrees of colour brightness. Monochrome Display Adaptor The IBM monochrome display uses a 9 [wide) x 14 [high) dot matrix to form the full range of ASCII characters which comprise 256 different letters, numbers and special characters. Alas, graphics are not supported. Upper and lower case letters are formed from 7 x 9 dots in the 9 x 14 matrix; a further 2 vertical dots are used by the character descenders [the hanging parts of letters such as g's and p's etc). The monitor requires the installation of a Monochrome Display Adapter [MDA) card to display 25 lines of 80 characters in alphanumeric mode [or text) mode. When you type a character on the keyboard, two bytes carry the information to the adaptor. The first byte is an ASCII code [between 0 and 255) defining the character shape. The second byte is called an attribute code and it determines JULY 1989 71 white or green, red and brown). In graphics mode at high resolution (640 by 200 pixel mode) only black and white are available, since it requires all of the adapter card's memory to define the on or off state of each pixel. Enhanced Graphics Adaptor In 1986 IBM released the Enhanced Graphics Adaptor (EGA) monitor, giving 640 x 350 pixels and more colours at the higher resolution. EGA has become the dominant graphics standard although plenty of software is still written for CGA (particularly games). The EGA display adapter supports the foregoing display standards while in monochrome and colour mode it supports a 640 by 350 pixel resolution and up to 64 colours (from the varying intensity of the signal). The monitor has excellent clarity for both text and graphics. MultiSync & VGA For any serious application involving graphic displays you need an EGA (enhanced graphics adapter) monitor. Naturally, for CAD or desktop publishing work, the bigger the monitor, the better. how the character appears (green on black background or reversed out of green etc). The resulting display is very sharp and easy to read. Since the IBM monochrome display has the standard text mode of 25 lines by 80 characters and each character is formed in a matrix of 9 x 14 dots, this means that its resolution is 720 dots (9 x 80) across by 350 (25 x 14) dots down. Colour Graphics Adaptor The IBM colour monitor enables operation in either black and white (monochrome) or colour. The Colour Graphics Adaptor (CGA) permits two basic modes of operation: alphanumeric (text) and graphics [also known as all points addressable or APA). This graphics mode allows any point on the screen to be directly defined 72 SILICON CHIP however the display is limited in detail by the resolution of the screen. Within each mode, several display character widths or pixel sizes are available for selection. The monitor uses a 5 by 8 dot matrix letter inside an 8 by 8 dot box with only one dot for the descenders. Consequently text isn't displayed quite as clearly as on a monochrome monitor but the graphics are quite acceptable. In text mode the display can operate in 80 character by 25 line mode. Colours are sharp with two graphics resolutions available medium resolution of 320 by 200 pixels, and high resolution of 640 (80 x 8) by 200 (25 x 8) pixels. In the 320 by 200 pixels graphics mode each pixel can have one of four colours. One of sixteen background colours may be used then three other colours selected from one of two palettes (cyan, magenta and The MDA, CGA and EGA graphics adapters were all designed for connection to TTL monitors and, for this reason, most manufacturers produce monitors which only accept this type of signal. Two of the newer (and consequently more expensive) types of monitors are the MultiSync and Video Graphics Array (VGA) displays. The MultiSync is a high resolution, colour monitor which provides crisp text and vivid colour graphics. The beauty of the MultiSync is its ability to automatically adjust to graphics board scanning frequencies from 15.5kHz to 35kHz with a maximum horizontal resolution of 800 dots and a maximum vertical resolution of 560 lines. The monitor can cope with any of the colour video standards, both digital and analog. While the MultiSync monitor copes well with horizontal frequencies, the vertical frequencies are set to that used by the CGA and EGA monitors - 60Hz. Adjustment of the vertical hold control should, however, adjust the monitor sufficiently to handle the 70Hz rate used for the latest type of monitor, the VGA. VGA is now emerging although TABLE 1: VIDEO MONITOR STANDARDS LOOK AT THESE BARGAIN PRICED KITS ·- Graphics Standard Video Bandwidth Horizontal Scan Vertical Scan OUR LATEST UHF REMOTE CONTROL MDA 720 X 350 16.257MHz 18.43kHz 50Hz X 200 14.318MHz 15.75kHz 60Hz CGA 640 Prices listed apply till August. EGA 640 640 X X 350 200 16.257MHz 14.318MHz 21.85kHz 15.75kHz 60Hz 60Hz 720 X 350 16.257MHz 18.43kHz 50Hz (EA JAN 89 and APRIL 89) • • • COMPLETE KITS TRANSMITTER & RECEIVER ONLY $49.90 Extra Transmitter Kits $17 .OD ea PASSIVE INFRARED MOVEMENT DETECTOR (EA MAY 89) • VGA • 640 720 X 640 X 640 X X 400 400 480 25.175MHz 28 .322MHz 25.175MHz 31.50kHz 31 .50kHz 31 .50kHz 350 25.175MHz 31.50kHz 70Hz 70Hz 60Hz 70Hz High Security, Low Power Consumption. Switch and Indicator Relays. Up to 50 metre range. Uses Special Dual Element Pyroelectric Detector. Kit includes two Lenses. SPECIAL BARGAIN PRICE $34.95 Interface Components $7 .95 extra. 16 CHANNEL UHF REMOTE CONTROL (EA NOV 88 and MARCH 89) • Package including Transmitter, Receiver and Four Channel Relay Driver, plus indicator. SPECIAL TILL END OF AUGUST EGA remains the defacto standard in the IBM compatible world. Most VGA and EGA cards are downward-compatible with the earlier CGA and MDA standards. Colour used to be a luxury which most software did not take advantage of but the demands of many products are making colour monitors increasingly prevalent. Because it is analog rather than TTL, the VGA monitor can provide up to 256,000 colours (although only 256 at any one time). The character size is 8 pixels horizontally by 16 vertically. Taking a step back, the question remains: what should you get? Again, it depends on what your needs are. If all you have in mind is word processing and spreadsheet use, an inexpensive monochrome monitor with reasonable resolution should do fine . But for more complex software, particularly in CAD applications, high resolution colour displays are essential. In fact, to use most CAD packages effectively, you need a large screen of say, 50cm or more. These cost really big dollars. That is probably enough on the subject of video monitors for the moment. Next month, we will have a look at the various graphics adapter "standards" available. ~ $119.00 THE MICROPHONE (EA NOV 86) • • • Professional Quality Up to 1 V RMS Output, Drives any Amplifier , even HI-FI Line inputs. Touch Control. COMPLETE KIT $24.99 MAINS MUZZLER (SC JAN 89) Short Form kit similar to the Mains Muzzler including the Torroid, 3x0.022uF/ 400V metallised polyester capacitors, 1M ohm 1W resistor and a 275V/40joule Varistor THE PRICE? ... ONLY $7 .40 That's less than the price of the Varistor! ULTRASONIC MOVEMENT DETECTOR/ALARM • • • • High Quality Crystal Controlled Kit. Prewired Transducers. PCB & Components plus ABS Case. Relay Output. COMPLETE KIT $42.95 BANKCARD, MASTERCARD and VISA ACCEPTED WITH PHONE ORDERS. P&P FOR ANY OF THE ABOVE $2.50. OATLEY ELECTRONICS MAIL: PO Box 89, Oatley, NSW 2223 SHOP: 5 Lansdowne Pde, Oatley West. PHONE: (02) 579 4985. RCS Radio Pty Ltd is the only company which manufa_ctures and sells every PCB f, front panel published in SILICON CHIP, ETI and EA. You can also buy some of our Kits at the following Distributors. Slightly higher prices may apply. NEWCASTLE MELBOURNE - 651 Forest Road, Bexley, NSW 2207 Phone (02) 587 3491 for instant prices NOVOCASTRIAN (049) 62 1358 ELECTRONICS WORLD (03) 723 3860 WOLLONGONG - ITEC (042) 26 4044 JULY 1989 73 IF YOU DON'T SHOP AT .JAYCAR YOU'RE PAYING TOO MUCH /::;;_~11 "CALL1'1ASTER" end of 111odel ANS\VERING 1'1ACIIINE BARGAIN 1 1~1•"' ''''',l, 1 \ . le · > **** Don't miss this one. 50 pcs only at this price. Was selling for $299. Almost 1/2 price>~':i:§::i~" NOW ONLY $159. SAVE AN UNBELIEVABLE $140. Callmaster Model TA-820 Dual Tape Answering system* Features • Length of message can be varied•· Announcement only • Incoming massage is voice controlled i.e. stops recording when caller hangs up, or can be fixed time • Monitor a telephone call • Rapid erase• Will answer after 2 or 4 rings• Use it as a dictation machine• Telecom approved. Cat YT-7030 ONLY $159 - SAVE $140 20 RANGE DIGIT AL MULTIMETER+ 10 AMPS+ DIODE CHECKER + ONE HAND OPERATION+ COMPACT SIZE I•JN I•OJNT Ul.,TltASONIC CLEANER This great new product will clean an amazing range of products including jewellery, glasses, dentures, watches, relays, switches, connectors. PCB's, pens, camera filters etc. The ultrasonic cleaner uses a transducer generator to produce millions of activated microscopic cleansing bubbles which blow dirt. grease and grime off surfaces, and deep into cracks and holes. 240 volt operation. 3 minute timer, ultrasonic frequency 40kHz. STOCK DUE EARLY JULY. Cat. YH-5400 A genuine low cost high performance digital multimeter at an unbelievable. Now everyone can afford a quality digital multimeter. Includes unique one hand operation feature whereby probes can slide mount into either side of the case so only one hand is needed to hold both the meter and the probe tip in contact with the test point. Slide mount will also store test leads and probes. LOOK AT THESE FEATURES • 3.5 digit LCD display • Diode checker • 1500 hour battery life Low battery indicator • Fuse protected ~ • Impact resistant yellow case ~ • Compact size 135x72x31 mm • High quality safety probes • Auto negative polarity • Tilting bail • 3 month warranty SEE CATALOGUE FOR FULL DETAILS Cat. OM-1410 * • * i,~ ""' -. cw, ;:,' JULY BARGAIN SAVE $10 ONLY $49.95 ONLY $199 AC MILLIVOLTMETER NE\\' K l'I' l'Oll JULY AUTOMATIC CHARGER FOR NiCads The model OT-2320 is a sideband Millivolt Meter for measuring from 0.3V to 100V in 12 ranges with bandwidth of 5Hz to 1MHz. Ref: EA July 1989 SPECIFICATIONS Volts 0.3, 1, 3, 10, 30, 100V in 12 ranges This kit is a fully automatic NiCad chargerthat dB -70. +40dB (OdB 1Vrms. OdBm=0.775V) is simpe and cheap to build Once the battery Accuracy ±'3% of full scale to 1kHz or 400Hz is charged, the unit automatically switches to Input n 10M ohm for each range, 40pF or l e s s * trickle charge. Next month a NiCad discharger Bandwidth ±'3% 20Hz. 200kHz to suit this kit will be presented. :±5% 10Hz. 500kHz Kit includes PCB, box, panel and all specified ±10% 5Hz. 1000kHz components. Power supply extra Amp Out 1Vrms at full scale soon ~ - - - - ~_C_ at_.M _P_-30 _2_0_$1_4_.95_ Power 240V 50Hz approx 5VA " Size 205(H) x 1BB(W) x 145(D)mm Weight approx 2kg Cat OT-2320 ! %• I ! SAVE $25 JULY BARGAIN i ONLY $200 * .:- ~ ' ' .rj _\ '2.9:,o n'!ln• 11.7 lJ flME' 1.S ~ BATTEflY,SJ;"L.ECT (h<>IJ!li) BIIU<!t¥ 1 Ah Cll«rt,e BY · . 10ClmAh · ,omA 2 AM 3 · AA 4 AA !i C&O HIOn1Ah l(knA ~OOrnAh 50mA 600mAl1 . 60mA U!:Ah 120n1A 10mm LEDs PCB Mount LEDs Were $1.95 ea Were 48~ ea NOW $0.95c ea NOW30c ea Red Yellow Green Orange Red Green Yellow Orange ZD-1956 ZD-1958 ZD-1957 ZD-1959 ZD-1780 ZD-1781 ZD-1782 ZD-1783 * ;;;;")~ 3 7D PLUG BARGAIN (37 way Cannon type D male) Another scoop purchase. PC board mount, straight pins. Normally $7 .95 each Cat PP-0861 NOW ONLY $5 for 10 or $30 for 100 ·· UNBELIEVABLE! STOCK UP NOW \• \'. 240 VOLT 15A 3 CORE MAINS LEADS A generous 3 metre long lead with a moulded 10A 240V plug (all grey) Normally$5value Cat PS-4110 ONLY $2 ea 111 VOLT CAI• BARGAIN SI•ECIAL BAGS 0.47µF 630V BACK CATPRICE$2ea AGAIN SPECIAL PRICE 20 for $10 For a short time only Contains about 2kg of That's 1/4 of normal price assorted goodies. Due to Cat. RG-5247 massive weight P&P is L':=========='. normal rates plus $5 COMPARE OUR PRICES cat xs- 9ooo ONLY You'll be pleasantly surprised! $14.95 RF CHOKE PACK ~ Over 50 pieces supplied. Normally $5 Cat. RC-5600 ~'-i --~ ( ~ '--._. ' JULY ONLY $4 Worth over $50. SALVAGE SOME CASH Turn your surplus stock into cash. Jaycar will purchase your surplus stocks of components and equipment. CALL GARY JOHNSTON OR BRUCE ROUTLEY TODAY ON (02) 747 2022 Quality Disks at Silly Prices Another Jaycar direct import. Would you believe• computer disks with a LIFETIME GUARANTEE for less money than you have ever had to pay before! 51/4" DSDD 48TPI DOUBLE SIDED /DOUBLE DENSITY l'tllXED POT PACKS Mixed Pots A pack of at least 35 potentiometers which includes slider pots• single and dual, an assortment of pots and tab style pots with assorted shafts and a selection of quality 5mm vertical sealed trimpots and open 5mm horizontal styles. This represents excellent value at $7 .. 50 Cat. RP-3902 $6.50 for 10 31/2" MF2DD 135TPI DOUBLE SIDED /DOUBLE DENSITY l~~. ~ •,'t" Cat. XC-4736 $26.95 for 10 51/4" DSHD 96TPI DOUBLE SIDED* /HIGH DENSITY c ~ ·' aQf' $18.95 for 10 - COMPUTER LEAD BARGAINS • 25D Male to 25D Male Normally $19.95 NORMALLY $7.50 SUPER BARGAIN 1.Smt Cat. PL-0856 JUNE ONLY $9.95 • 25D Male to 25D Female Normally$1995 Yet another great facto,y surplus buy. They lose• you SAVE Bargain 1 12 volt lluminated pushbutton switch. Green bezel. as used in expensive car alarms. (Momenta,y on/off). 12V lamp supplied. Rectangular N . 0 . / N i } C contacts. Normally $15.95 ONLY $7.50 10+ $6.50 ea BELOW 1/2 PRICE • t1 SAVE $10.00 1.SmtCat.PL-0854 JUNE ONLY $9.95 SAVE $9.00 ,\ , .., $2 each • ~,. · •• Bargain 3 Type 'J' thermocouple. Will measure from -200'C to +850'C!! Supplied with 650mm varnish impregnated glass fibre sleeving. Supplied with full data. AN AMAZING $19.50 Cat. ZT-9400 Bargain 4 Thermal cutout switches. As used in hair d,yers. etc. Ve,y handy. Cat. ST-3800 77'C $2 Cat. ST-3810 128'C $2 PCB mount. high quality , 10♦ $3.SOea Cat SY-4048 Bargain 6 Piezo buzzer 3-20 volt 24mm diameter. PCB mount. Pins 15mm apart. Height 17mm. Operating frequency 3800Hz. 85dB sound pressure. 49 • NEW KIT S C · tereO OmpreSSIOn for CD Players Ref Silicon Chip March 1989 You asked for it! After many requests from readers for this project. here it is. This simple compressor circuit reduces the dynamic range of CD's so that you can make good recordings. Kit includes PCB. box and all specified components. (12V AC plugpack not included. Cat. MP-3020 $1495). ~ • ---;================$4c9:so • * The Sensational 30 PIECE ENGINEER'S DRIVER SET 10+ $1.50 ea Cat. HK-7100 • • • , Bargain 2 Cat. AB-3458 JUNE ONLY $9.95 •CentronicsPlugto25DMale Normally$1895 BUY BOTH PACKS FOR $5 SAVE $10 SAVE $10.00 1.Smt Cat. PL-0855 , Collet fixing instrument knob. Will accept 1/4' or 6mm pot shafts. 36mm diameter. 19mm height. Black polypropylene. Snap on capcoverwithwhitemarker . supplied bu not pictured. , , Quality. ·• $4.95 10+ $4.50 ea "1:1 -o · You don't see this very often. A pack of 20 slides in assorted values between 5k and 500k. 20 for $7.50. That's less than 40e each! The majority are dual gang which have been selling for $5.50 each. A typical pack includes values such as 5k, 50k, 1OOk, 250k and 500k in 45 and 60mm lengths . in single and dual styles. Cat. RP-3903 SAVE 50% on normal price ONLY $3.95 • Slider Pots All disks are supplied with envelope, index labels and write-protect tabs. Remember. these disks might be cheap but they are good quality. We are so impressed by the quality we are happy to offer a lifetime guarantee. : v~r..~~ ~"~ - '\ ~ ('I":•~"~ • Cat. XC-4732 Cat. SP-0750 ****** NORMALLY $7.50 Cat. XC-4730 Here's what you get: • 5 Slotted Bits 0-1,3-4, 5-6, 8-10, 12 • 5 Hex Bits 3/32'', 5/64", 7/64", 1/8", 9/64" • 4 Philips Bits No. 0, 1, 2 & 3 • 4.Square Recess Bits No. 0, 1, 2 & 3 • 6 Torx Bits T10, T15, T20, T25, T30, T~ • 2 Pozidrive Bits No. 1 & 2 • 1 x 1/4" Drive Socket Adaptor • 1 x 1/4" Drive Hex Bit Holder And its all housed in a sealable tough plastic case. Cat. TD-2000 $19.95 VERBATIM DISKS AT UNREAL PRICES Compare our prices with your normal supplier. Description 1-9 Boxes 3.5' 1S/2D Cat. XC-4720 $39.95 3.5' 2S/2D Cat. XC-4721 $46.95 35' 2S/HD Cat. XC-4722 $99.00 5.25' 1S/2D Cat. XC-4725 $22.00 5.25' 2S/2D Cat. XC-4726 $26.00 5.25' 2S/HD Cat. XC-4727 $41:00 240/110V Stepdown Transformer Bargain Jaycar has secured a quantity of fully enclosed 250VA-240/110V stepdown transformers. Each unit has a generous 1.7m long inlet (240V) cord with 3 pin mains plug. The 100V side has a cord 0.5m long. The transformers are brand new and locally made and measure 115(H) x 148(D) x 95(W) (not including inlet/outlet cords) Weight is 5.3kg - so $6 extra postage applies over and above our 10+ Boxes $37.95 $43.95 $89.00 $21.00 $24.00 $39.95 THOUSANDS SOLD - normal P&P charges. Brief Spees: 240V input: 50Hz 1.14A max 110Voutput: 50Hz 2.17A max All power wiring enclosed. ** lit' T lit' T lit' T ONLY $99 NORMALLY WORTH $199 Cat. MS-1080 (Only $20 dearer than our 125VA unit which is not enclosed wiring). EXTENDED TRADING HOURS!! Dummy Camera Bargain - 25 % OFF Parramatta Gore Hill Hurstville York Street Springvale Melbourne City Buranda Old We have made a great purchase of realistic looking dummy TV cameras. They are Australian made, are supplied with adjustable swivel mounting bracket. fixing screws, flashing LED circuit board and 2 flashing LED's. Also supplied is the 2 x D cell nylon battery holder to power the flasher circuit. Sat till 4pm, Thurs till 8.30pm Sattill 4pm Thurs till 8.30pm Thurs till 8.30pm Sat till 2pm, Fri till 8.30pm Fri til I 8.30pm Thurs till 8.30pm NE\\' KIT J?OR JUNE TOUCH LAMP DIMMER * Ref: Silicon Chip June 1989 So new, in fact, we don't have many details on it. Uses brand new Siemens chip which will hold the light level when switched off - then on. Remote option available later. Cut. KC-5052 $32.95 KNOB PACK Another Jaycar Surplus Deal. . We have a quantity of Japanese Sato brand knobs, some lovely aluminium, some black and aluminium and some are just black. We also have a quantity of Rean knobs with different coloured caps. The Sato knobs are imperial and the Rean metric. This pack will include a minimum of 50 knobs generally more. The majority will be Rean knobs - with caps and the remainder Sato. The Rean knobs are worth about $1.20 each and the Sato up to $2 each. We figure there is about $60 worth of knobs. Cat. HK-7050 ALL YOURS FOR ONLY $10 Cat LC-5310 LIMITED QUANTITY WAS ***** * 1-4 $49.95 5-9 $42.95 10+ $39.95 'ii\.' _... NOW $37.46 $32.21 t r : - - - $29.96 all each Another surplus buy. Quality English brand wrap around clear seal markers. Consists of a sticky patch 72mm x 25mm with a writing surface 25 x 25mm up one end. Sticker is then wrapped around the cable. Max cable diameter 16mm. PACK OF 60 Cat. NL-4150 __..----,.,,,."~$4.95 LARGE SCREECHER SillEN Unbelievable ear splitting sound, 120d8 of it. Operates on 12V and draws 300mA .. Ideal for burglar alarms where deafening sound is required and space is not a problem. Size 11 OIW) x 85{l) x 1OOIH )mm Cat. LA-5720 WAS $24.95 NOW $19.95 SAVE $5 6 WAY POWER OUTLET WITH MAINS FILTER Not only is it a 6 way power board. it incorporates a voltage surge and spike protector and noise rejection filter network. Supplied with two metre cord and mains plug, safety shutters on each outlet. Illuminated master on/off switch and even a safety circuit breaker. NOTE: If you require absolute mains Cat. MS-4030 ~ suppression don't forget our Australian ~ made Squeaky Clean Mains Filters. SMOKELESS ASHTRAY WHAT A FLOP We really thought this was a good product, but we were wrong. See our catalogue for full details. ~ 1/2 PRICE WAS $14.95 NOW ONLY $7 .SO Cat YX-2930 '\\ ~ . ~ $59.95 ALARM PANEL * TELEPHONE DIALLER ** This is a marvellous product which will connect□ virtually any home/ business alarm panel. It has a built in microphone which records a 16 second message by you and then when the alarm is triggered will send the message to up to four different numbers, or any combination of the same. Suitable for tone and pulse systems. Also suitable as an alerting system for the elderly or sick. Easy to connect to both alarm system IN/C terminals) and telephone 12 wires). Requires 12V DC - from alarm panel. We have seen this product for $249 in other electronic catalogues. Cat. LA-5190 ONLY $159 OPEN AN ACCOUNT SYNTOM - Drum Synthesiser Ref: Silicon Chip May 1989 Fantastic drum synthesiser kit that will add real depth to any performance. See the 1989 Jaycar catalogue for full details - Page 15. Cat KJ-6502 $42.50 ********* Jaycar is quite happy to provide ACCOUNT FACILITIES for the following: • All schools (Government and non Government) • All CAE:s. Colleges, Universities, etc • All State and Commonwealth Govt. Depts. including research institutions • All mining companies • All TV and Radio stations • All public i.e. "LTD' not Pty Ltd companies • All Ply Ltd companies must apply for an account, please ask for an account application form PCB TERMINAL STRIP BARGAIN These are high quality 10 way thermoplastic PCB terminal strip. As used extensively in the alarm industry. Units are supplied unassembled i.e. you have to screw the screws in. These are normally $4.95 cat HM-32os 'AT LAST! Easy, Economical Cable Markers Cat Price $2 95 ea • This month Pkt 10 for only $10 Sorneti mes the products we advertise are so popular they run out within a few days. At other times unforeseen circumstances might hold up shipments so that advertised lines are not in the stores by the time the advert appears. And, very occasionally, an error may slip through our checks and appear in the advert (we're human too). Please don't blame the store managers or staff, they cannot control a dock strike or a lost PCB artwork from a magazine to the PCB manufacturer for a new kit, or fix an error that appeared in print. If you are about to drive across town to pick up an advertised item, why not play it safe and call the store first- just in case. Thanks. Mixed Semiconductor Pack Brand new pack just finished. Guaranteed minimum 100 components supplied but packs generally excued this amount. IC's, transistors, diodes, LED's, RAM. etc. Cat. ZP-8990 ONLY $10 Compare Jaycar's everyday low, low prices with your current supplier. Here are some examples . .. l])<at>~P'iJ' 'iJ)c,\'\1 ®<at>~P'iJ' ®<at>~P'iJ' CP&W <at>a~c®® ®<at>~P'iJ' [Pc,\'\1 Cat <at>tBo<at>® A 1 .2AH GEL BATTERY Q ONLY $22.50 Cat SB-2480 ®<at>~P'iJ' [Pc,\'\1 <at>~®o<at>® 1.00 5mm Red LEDs ZD-1692 $15.50 5 100 Mixed LEDs $19.50 <at>~P'iJ' 'iJ)c,\'\1 <at>~o<at>® cat. SP-om $16.95 INSULATED STAPLES 240volt - 30 watt Cat. TS-1450 Another surplus stock buy 2 sizes - 1/2" and 5/8". Boxes or 100. WAS $2 per box <at>~®c®® Worth over $2 each TRIMMER CAPACITOR BARGAIN Cat. TH-1900 ®<at>~P'iJ' {r®Q' ~ 'iP&W <at>ac~® •• • SPECIAL 20 for $5 ONLY $75 CABLE JOINERS $1.25 for 4 Cat. HP-1206 <at><at>~P'iJ' 'iJ)c_\'\1 Ideal replacements. 3 wire connection . angled shaft for key. Size 15mm x 15mm x 30mm high. SUPERTOOL <at>~c®® {{ COMPUTER KEYBOARD SWITCHES See catalogue page 116 for full details INDOOR BALUN ONLY $2.25 CatLT-3022 JAYCAR SOLDERING IRON J ~ , -;;, •• Cat. SB-2452 0 10+ $13.95 ea <at>~®o®~~ <at>a<at>c®® 0 ONLY $14. <at>~tBc®® Cat ZD-1694 NEON TEST SCREWDRIVER ONLY $2.20 Cat. TH-2048 ®<at>~P'iJ' Grab some while they last, which won't be long at this price. Limited quantity. Size 40mm wide 85mm high including terminals. Cat. RU-6715 Cat. RE-6250 <at><at>~P'iJ' 'iJ)c,\'\1 <at><at>~P'iJ' 'iJ)c,\'\1 ELNA COMPUTER CAPACITOR 27,000µ F 35V Can 55 Electrolytlcs $6.50 0· . 4 [Q)<at>~P'iJ' [Pc,\'\1 ~ 'iP&W <at>a~c®® 10mm HEATSHRINK - 1 metre ONLY $3.00 Cat WH-5535 • <at>)<at>~P'iJ' 'iJ)c_\ 'D7 Cat. ZT-2218 60 Greencaps $7.95 <at>~o<at>® AA NICads ONLY $12.50 for 4 1 •9 $1,60 EACH - - 10 · 99 $1.20 99+ $1.00 Cat. RG-7199 ~ MERCURY SWITCH ONLY $2.25 Cat. SM-1035 Another surplus buy. This time a Philips transistOf • BUS 11. Spees. NPN. T03. lcA · 5, Vceo · 400, Vcbo · 850 This device would normally cost about $8. Don't miss out. PACKS AT BARGAIN EVERVDAV PRICES , DPDT 3A 125V TOGGLE SWITC ONLY $2.35 Cat. ST-0572 <at><at>~P'iJ' [Pc,\'\1 <at>tBo<at>® ~ BUS-11 HIGH VOLTAGE TRANSISTOR BARGAIN CP&W <at>®® Another surplus stock purchase. Quality Japanese made with lead spacing standard 5mm. Capacitance 20-60pF. • ~ High quality. Cat. RV-5710 SPECIAL 50~ ea ·. - 10+ 40Q ea I ~ NOW ONLY • ~f c? t< ~ 1~~51!?a? HP-11Bs FOOTS WITCH High quality. Mounted in heavy metal case with non scratch base and non slip top. 1 metre shielded cable terminated in 3.5mm plug for switch contacts. Momentary switch action. Quality microswitch will not accept high current or voltage. Made in japan. Cat SM-1015 WAS $12.50 1 . ~~';; l, 1 ::::( : I a~:!!! VIS4 Ill I SYDNEY · CITY PARRAMATTA CONCORD =-..,J HURSTVILLE NOW ONLY HEAD OFFICE 115ParramanaRoadConcord2137 Telephone (02) 747 2022 Telex 72293 FACSIMILE (02) 744 0767 MAIL ORDER VIA YOUR 117 York St. (02) 267 1614Mon-Fri 8.30 · 5.30 Thurs 8.30 pm - Sat 9 - 12 355 Church St (Cnr. Victoria Rd) (02) 683 3377 Mon-Fri 9 • 5.30 Thurs 8.30 pm• Sat 9 • 4pm 115 Parramatta Rd (02) 745 3077 Mon-Fri 8.30 • 5.30 - Sat 8.30- 12 121 Forest Rd (02) 570 700l Mon-Fri 9 - 5:ll) Thurs 8.30 pm - Sat 9 - 12 7 .50 MAIL ORDERS P.O.BoxlBSConcord 2137 HOTllNE 02 7471888 FOR ORDERS ONLY TOLl.fftEE (008) 022.888 1:f $25-$49.99 $50-$99.gg OVER$100 s 3.15 $ 450 $ $8.00 s:so ROAD FREIGHT ANYWHERE IN AUSllW.IA $13.50 GORE HILL BURANDA QLD MELBOURNE-CITY SPRINGVALE VIC POST a PACKING $l0-$24_99 188 Pacific Hwy (Cnr. Bellevue Ave) (02) 439 4799• Mon-Fri 9 • 5.30 Sat 9 - 4pm 144 Logan Rd (07) 393 0777 • Mon-Fri 9 • 5.30 Thurs 8.30 - Sat 9 - 12 Shop 2. 45 A'Beckett St City(03) 663 2030 Mon-Fri 9 • 5.30 Fri 8.30 - Sat 9 - 12 887-889 Springvale R'oad Mulgrave (03)5471022 Nr Cnr. Dandenong Road Mon-Fri 9, 5.30Fri 8.30 • Sat 9 • 2 THE WAY I SEE IT By NEVILLE WILLIAMS Police radar: where it works & where it doesn't Whether you know it or not, if you are booked for speeding by police using radar you have virtually no way of challenging it. This is despite serious reservations about its accuracy. When only one car is on the road, police radar is accurate. But if you are booked while travelling with other cars, you may not be the one at fault. You're driving along a two-lane country road in bright sunshine, chatting with your passengers and content with the world at large. The road is clearly sign-posted 80 km/h but you're consciously keeping up with the rest of the traffic at 90 kays or more, neither passing nor being passed. A police car looms up ahead, travelling in the opposite direction and you're silently thankful that he's going the other way. Of course, he could have had forward-looking radar but you dismiss the thought and go right on talking. But then you suddenly become aware of a wailing siren and there he is in your rear vision mirror, signalling you to pull over. You do so, wind down your window and, before your silent passengers, are officially advised that you were exceeding the speed limit when he passed you a couple of kilometres back. Even though everyone else appeared to be doing the same, you were undeniably exceeding the speed limit for that particular stretch of road. Not only that but you'd been indiscreet enough to leave a sufficient gap between you 78 SILICON CHIP and other cars travelling in the same direction to be exposed unambiguously to the radar beam. As for your friends, their reaction is typical: "Tough mate, yer gotta keep yer eyes open on that stretch" - not so much for road signs but for police! I didn't invent the above scenario; it happened to me a few months back, after 50-odd years on the road without a "bluey". Now, I am much more circumspect about keeping to the speed limit. It's quite difficult though, especially in traffic. Speed, a chronic problem If you doubt that statement, try sticking to 60km/h along ordinary suburban routes or the approaches to any country town. Most cars will pass you and disappear into the distance, many of them at a considerable rate of knots. Yes, I know the routine argument that the speed limits are unduly restrictive and that a good driver (is there any other kind?) will know when they can be exceeded without risk. And I know that the police are reputed not to worry too much about moderate infringements. Oh yes, and that a driver observing the limit is more of a hazard than one running with the traffic, because he/she "forces" others to pass. The simple fact is that speed limits apply nationwide and are meant to be observed as one means of curtailing our appalling road toll. They are abused, often flagrantly and dangerously because, in the absence of overt law enforcement, motorists "rationalise" their many and varied reasons for ignoring the speed limits and, in many cases, a few other safety measures as well: double lines and red lights, for example. Police radar Drivers dislike police radar because it poses a covert threat to their heavily rationalised disregard for the letter of the law. Why shouldn't they be able to add a modest 10 or 12km/h to the statutary limit if they're an experienced driver in a good vehicle, and/or the road is clear and dry, and/or they're running a bit late for whatever? Anyway, what guarantee do the police have that their radar is accurate? Haven't we all read about court cases where the charge was thrown out because the defence was able to cast doubt on the equipment, or the conditions under which the particular reading was obtained? Yes, I certainly have seen such reports and I've also noticed, at times, that the expert witnesses who've managed to discredit the ~~ ------'□ Ii.,..,______ RADAR (STATIC) I- TARGET R - - - - - - - (MOVING) Fig.1: When the distance between the radar equipment and the target is changing, Doppler effect produces a proportional shift in the apparent frequency of the reflected signal. The total path for the returned signal is 2R. , __ - tD ~--~~ ----=-& STATIC RADAR (a) I (b) . le FREQUENCY I I I (c) 14 13 ~ le l 11 I• 12 FREQUENCY ,. FREQUENCY Fig.2(a) shows a typical police radar set-up with a roadside testing station and four cars being scanned by the beam. Spectrogram (b) shows the signal frequency transmitted by the radar test set while (c) shows the signals received as reflections. Signal f1 is from vehicle 1, f2 is from vehicle 2 and so on. Spectrogram (d) shows the signals after they have been mixed, showing that the directional information is lost. This is why police radar accuracy is suspect when more than one vehicle is on the road. radar evidence in court have been elevated to the role of folk heroes, with other less fortunate drivers sharing vicariously in their victory over the police. The way I see it, on the balance of probability, most of the drivers picked up by radar will have been guilty anyway, despite alleged technical imperfections of the equipment or the way it is operated. It's fair enough that the accuracy of radar speed measurement should be challenged in contested situations but now that appears to be largely a thing of the past. If you are booked, that is virtually it. You front up and pay your fine or else! From the IREE "Monitor" Having made my own position clear, let's talk about an article published in the IREE (Institution of Radio & Electronics Engineers, Aust) "Monitor" for March 1989. Entitled "At Question The Overall Performance of Police Traffic Radar", it was written by Dr J. G. Lucas, of the Air Navigation Group, School of Electrical Engineering, University of Sydney. That Dr Lucas has strong reservations about radar-derived information is indicated in the introduction to the article where he refers to the fact that: "it was possible recently for the most sophisticated and up-to-date defence radar with its vast computer support on board a United States ship to mistake a commercial airliner for a small fighter/bomber with the ensuing disastrous consequences''. In the face of this, he continues: "It is perhaps not too hard to imagine that the traffic radar devices that are used on our roads can also make mistakes. Traffic radars ... are relatively unsophisticated devices' '. The final sentence in the introduction is the one around which the whole article revolves: However, legislation is being passed through Parliaments in Australia which decrees them to be infallible scientific instruments. As someone who has spent his whole career in electronics, I think that the idea of defining accuracy by legislative decree is ludicrous. Whether designing instruments or using them, accuracy has always been dependent on technical excellence - and is marked by progress along a never-ending learning curve. The measurement equipment we valued yesterday is questioned today and replaced tomorrow. That's the way it's always been. All states have, in fact, passed the legislation referred to by Dr Lucas so that now police radar is legally infallible. This defies precedents involving just about any kind of electronic equipment that was ever made - particularly if it involves a human input. Modern solid-state electronics can be good, frequently very good, and in some cases even superb. But infallible? In the minds of salespersons and politicians it may be but certainly not in the opinion of engineers. So what about radar, as used in JULY 1989 79 X-BAND RADAR CROSS SECTIONS 100 40.5 14.6 10 1.0 0. 1 0.1 .0 1 .005 .oo6T .00 1 ..,_ "' c:, :. "'z: ,_= = 31: "' cz: c:, c:,a:: ci!i > ::, ~~ 31: !l: z: cC w- "' ="' ,_ 35 = ,_ ,_ "" cc< c:,a.. 31: Ill z w "' I Cl z: cC ....► ....w ....w "' ,_ "' c:, c:, w ::, w "' a.. c., ► u cc ,_ c:, c:, :. cC Cl z c:, = 143.8 100 10 ... c., ::,- 10.2 1 1.0 0.16 0.1 0.16 .061 .01 .001 Ku-BAND RADAR CROSS SECTIONS Fig.3: using a Volkswagon Kombi Van as an arbitrary reference (1.0) for X-band and Ku-band radars respectively, this diagram illustrates the enormous difference in radar cross section between a Kenworth truck approaching (therefore front-on) and leaving, a Peugeot 505 and a motor bike. Australia? According to Dr Lucas, police radar typically involves a solid-state Gunn diode oscillator operating at X band (10.525GHz) or Ku band (21.15GHz) and producing some tens of milliwatts RF output, which is fed to a waveguide horn antenna. In the case of X-band equipment, the beam width is typically 20° between 6dB points, so that there is likely to be significant radiation over a 40° arc. In the Ku band, these figures are typically halved. In operation, the transmitted signal is directed towards the target vehicle. Some of the signal is then reflected from the target back into the horn for resolution by a zero IF (synchronous) receiving system (Fig .1 ). If the target vehicle is moving towards or away from the antenna, a Doppler shift is apparent in the frequency of the reflected signal amounting to approximately 20Hz per km/h at X band, and 45Hz per km/h in the Ku band. The return signal is higher in frequency for approaching vehicles, lower for those moving away. 80 SILICON CHIP will by the use of critically phased twin mixers - thereby alleviating that particular problem. This is the basis of the so-called "Slant" radar. In the mobile radars used in NSW, an IF sweep system searches for and locks on to fastest target. However, the system still can't distinguish between approaching and receding vehicles. In his opinion, the best scientific approach would be a procedure involving a Fourier Transform Algorithm which would provide accurate estimates of the speeds of all vehicles in the field of view. But, he says, "So far as is known, NO units throughout Australia use the Fourier Transform approach". The potential accuracy of speed measurement for an unambiguous target is typically well within 1 % . The catch in that statement lies in the phrase, "unambiguous target". As we shall see, an unambiguous target is not easy to obtain. In the midst of traffic, a simple stationary radar module is presented with multiple potential targets. It will sense multiple returns dispersed on either side of the transmit frequency, according to the speed of the vehicles and the direction in which they are travelling. This is shown in the spectrogram of Fig.2. This is confusing enough but, after mixing the transmitted and reflected signals, the directional information is lost because the resultants share a common IF spectrum. This means that the radar system cannot tell whether the measured speed is from an approaching vehicle or one that is moving away! Dr Lucas states that, in more advanced systems, it is possible to cancel the returns from either approaching or departing traffic at Radar "cross section" The other problem which prejudices the "infallibility" of speed radar is that of radar cross section. Some vehicles reflect a large amount of the radar signal while others reflect only a little. Many cars reflect less signal than motorbikes and some sports cars are practically invisible to radar, particularly if their pop-up headlights are down. Comprehensive tests, carried out at Sydney University, confirm this proposition. The tests involved driving typical vehicles towards X and Ku band traffic radars, with provision to photograph oscilloscope displays at the instant each approaching vehicle triggered an electronic gate. The results were plotted in terms of the vehicle's apparent radar cross section in square metres, as related to a hypothetical perfectly conducting sphere of equivalent cross sectional area. As will be apparent from Fig.3 (and I quote from the original paper) "there is NO simple relationship between the size of a vehicle and the return which it provides to a traffic radar device - it depends on the particular vehicle shape. "For example, the Peugeot 505 gives a smaller return than a motor bike. Some of the slick modern sports cars which are similarly virtually invisible become instantly significant when they raise their headlights". In the worst case, radar equip- MOBILE RADAR ment will tend to lock onto the vehicle with the largest radar return, irrespective of the direction in which it is travelling and without any direct indication to the operator as to the particular vehicle involved. In practice, a similar return could be expected from a Peugeot 505 approaching from 50 metres away, a large truck travelling 350-odd metres behind it, and the same large truck travelling in the opposite direction over 450 metres away! In mobile mode, Dr Lucas concedes that typical equipment can give an accurate reading when the two vehicles are alone on the particular stretch of road. The equipment assumes that the fastest vehicle return will be the converging speed with the target vehicle, from which it must subtract the speed of the patrol vehicle. However, he says, the devices will continue to give an ostensibly "valid" reading when there is more than one vehicle in the field of view. Continuing: "In the worst case, the operator will continue to get a reading when there is traffic moving in the same direction as the patrol vehicle". Why? I don't quite follow unless he has in mind a large truck several hundred yards ahead of the patrol vehicle really burning up the bitumen! The point he does stress, in closing, is that the operator of a radar patrol vehicle has precious little time to make checks and decisions and the opportunity only to make the briefest of notes about the details of any one incident. His conclusion: "All traffic devices do operate extremely accurately when there is only a SINGLE target vehicle on the roadway. In ANY instance where there is more than ONE target vehicle, there is ALWAYS doubt as to which vehicle the radar has acquired". Fig. 4: in mobile mode, the radar assumes that the highest reading is the converging speed with the target vehicle, from which it must subtract the speed of the patrol vehicle. The way I see it While I have not studied the subject in detail, I would be surprised if Dr Lucas' article says anything that has not been said at other times as, for example, in anti-radar court proceedings which have been reported in the media. What it does do is to restate the case against existing traffic radar systems in an organised and relatively unemotional way. In the face of such doubts, it is ludicrous that Australian Governments have decreed such devices to be an "Infallible Scientific Instrument". Courts are now presumably obliged to accept radar evidence and reject defence submissions seeking to discredit it. As I said at the outset, my motive in publicising Dr Lucas' paper is not to see traffic radar totally discredited. As one means of enforcing speed limits, it has a contr.ibution to make to saving lives on the road. But to impose by law a fictional "infallibility" which cannot be supported scientifically would be a clear miscarriage of justice. The end certainly does not justify the means. Defence must be preserved as an option for those who choose to plead "not guilty". And if, as a result, traffic radar needs to be rendered more credible by improved technology, by automated realtime documentation or by photographic evidence, so be it. Reference If you want to study Dr Lucas' article in detail, you can get a copy from the IREE Head Office. (Commercial Unit 3, 2 McLean St, Edgecliff, NSW, 2027. Enclose $2.00 to cover photostats and postage). ~ MAKE YOUR DREAMS COME TRUE LAPTOPS FROM s1995.oo * INTERNAL BATTERY, EXTERNAL AC ADAPTOR *LIGHT, FAST, 10MHz *COMPACT AND CONVENIENT * SUPER TWIST LCD DISPLAY *64OKB RAM *SERIAL AND PARALLEL PORT * REAL TIME CLOCK LASER PRINTER s2995.oo *6 PAGES PER MINUTE *SERIAL AND PARALLEL (DUAL HOST) * 6 BUil T-IN FONTS * HP LASER JET SERIES II EMULATION * OPTIONAL IBM PROPRINTER EMULATION * 4 ADDITIONAL SOFT FONTS INCLUDED * EXPAN DABLE TO 4.5MB COMPUTER CARE KIT s115.oo * 6 CLEANING KITS IN ONE *SUITABLE FOR ALL COMPUTERS _;<t··::..._,,,_...,,,.....,, - - - - -- zz:. •! ,,l-~ ALL PRICES INCLUDE SALES TAX FREE ALL PURPOSE CLEANING KIT WITH HARDWARE PURCHASES FREEPOST NO. 31 ESCKAY PRINTERNET PO BOX 2591, NTH PARRAMATTA, 2151 TEL: (02) 630 8956 JULY 1989 81 TWO 86 CLASS LOCOS HEAD up a long train of empty wheat wagons. If the wagons were full, each loco would have both pantographs raised to cope with the huge currents required - over 5000 amps during starting. THE EVOLUTION OF ELECTRIC RAILWAYS Among the most powerful locomotives in use in Australia today are the NSW SRA's 86 class electrics. These are big locos with large driving wheels and they draw enormous currents from the 1500-volt DC catenary. This is the story of the 86 class. By BRYAN MAHER This is an account of a typical freight train operation in New South Wales, starting from Enfield marshalling yards, bound for the western district of the state. Typically, the train will be a mixed assortment of freight cars, all having 2-axle bogies, rated for express speeds. Many of these will be large black louvre vans carrying thousands of cartons and crates from Sydney retailers, small manufacturers and wholesale markets, PT.21: THE NSW 86 CLASS ELECTRICS 82 SILICON CHIP bound for customers living anywhere from Orange to Bourke. There can also be a string of VLine vans brought up on an all-night run from Victoria. The SRA western fast freight was timed to wait for the arrival of the cars on the Melbourne-Sydney-Brisbane overnight express freight, but today the wait had been longer. Finally though, the vans have all been marshalled and the train moves out of Enfield and joins the main western line. For the first part of the journey on the electrified section over the Blue Mountains to Lithgow, the train is pulled by two 86 class electrics. After passing though Parramatta the train begins accelerating for the fast run to Penrith. Each 86 class loco has six 470kW seriesfield 6-pole DC traction motors. These are all switched into the series starting configuration, and wound up to speed as the driver eases up the master controller notch by notch, cutting out series resistance. Each locomotive can exert a starting traction of 420kN (equivalent to 42 tonnes). This is available for the first 10 seconds and as speed builds up, the maximum drawbar pull is reduced to 315kN, the normal acceleration rating permitted for five minutes. As the heavy train gains speed, series starting resistances are progressively switched out by camshaft contactors. In bridging out resistance sections, these camshaft contacts do not break traction currents, so contact burning is minimised and blow-out coils are not needed. TWO 86 CLASS LOCOS pull a long passenger train up a steep grade on the Blue Mountains line. Their maximum rated speed is 130km/h but this is not possible on this section because of the many curves in the line . camshaft contactors to connect large resistors in parallel with the motor field coils. This diverts some motor current away from the coils, to weaken the motor 's magnetic field. When this happens, the armature will build up speed until it again generates a back voltage nearly equal to the applied line voltage. For still higher speed settings of the driver's controller, a number of these field-shunting camshaft contactors will close to divert even more motor current away from the field coils. Maximum field shunting in the 86 class reduces the field current to 37% of the motor armature current, allowing the armature speed to rise as high as 2820 RPM which gives the maximum rated loco speed of 130km/h. The field shunting control camshaft is driven by a pilot motor, controlled by solid state electronics. The ·contacts in the field shunting circuit, because they may break currents up to about 500A, are fitted with magnetic blow-out coils and arc-chutes for arc extinction. To smoothly manage the available acceleration the 86 class locos are fitted with automatically timed controllers for the traction motor circuits, including weakfield runn- Weakfield operation Having reached a speed of around 35 to 40km/h (depending on track gradient, train weight and line voltage] the traction motor armatures, rotating at about 740 RPM, will be generating a back voltage almost equal to the applied line voltage, so the motor armature will rotate no faster as long as the series field coils carry the full motor current. If the driver wishes to accelerate the train to higher speeds the control system then closes additional THE 86 CLASS IS NOT THE most inspiring sight when viewed side on. The ventilator panels are for the compressed air ventilation fans which feed the traction motors and provide cooling for the large starting resistors. ]ULY1989 83 AN 86 CLASS LOCO PULLS into Central Station in Sydney with the Brisl;,ane Limited. On some occasions this train has been diverted over the Harbour Bridge and through the City Circle line. ing, the auto-timed notching process switching the series resistors out of circuit as camshaft operated contactors bridge out resistance sections. The secret of the wonderfully succ'e ssful design of the 86 class is not apparent to the casual observer. How can this locomotive, continuously rated at 2.7MW and with a one-hour rating of 3.328MW exert so much tractive effort? How can the continuous tractive effort of 222kN be extended to double that figure (420kN) for the vital first 10 seconds needed to get a long heavy train moving? Many other classes of locos use a low motor-to-driving wheel gear ratio to achieve high tractive effort, but this prevents them attaining high speeds. Yet the SRA 86 class does achieve both a high running speed of 130km/h and a very high tractive effort. And 'to put the icing on the cake', that enormous tractive effort is achieved (usually) free of wheelslip troubles. Comparisons The SRA 86 class has often been compared to locomotives of other 84 SILICON CHIP railway systems, including the South African 10E and 1 lE classes and the Queensland 3100 and 3500 class 25kV AC locomotives. These use thyristors to control the traction motors, the latter class using a radar system for speed measurement and ultimate control of wheel slip. In the SRA 86 class though, no radar nor thyristors are used, the motor control being solely by mechanical switching as we have seen. This overall scheme has been applied many times over the years in many classes of DC locomotives, so why are the 86 class more successful than many other DC and AC machines? The secret is threefold. • A DC traction motor on a straight DC supply can be given a greater short-time overload characteristic than the same size DC motor in an AC locomotive with rectifiers. • As well as the usual incremental resistance steps in the starting circuit, between each resistance step a second "vernier" resistance bank comes into circuit which in turn contains incremental resistance steps. By this means, the five sections of the main starting resistor are effectively each divided into five vernier resistance increments, equivalent to a starting resistor with 25 individual steps. Furthermore, these 25 effective resistance changes occur in each of the "series", "series-parallel" and "parallel" configurations, making the whole motor control as smooth as a 75 step controller. Thus the voltage applied to each motor is so gradually increased from start to full parallel connection that the tractive effort rises smoothly, resulting in excellent driving wheel adhesion (to the rail). • Wheel slip under ordinary conditions is unlikely but if the driving wheels should slip under severe acceleration or greasy rail conditions, this is automatically corrected. Should any two driving axles differ in rotational speed by as little as 0.4 revs/sec or if any axle accelerates at more than 0.8 revs/ sec2, as sensed by the axle speed generators and associated electronic circuitry, contactors automatically close to shunt the offending motor's armature with a resistance of suitable value. This reduces the torque exerted by that motor until its speed comes back to match that of the others. Rail sanding is resorted to only in extreme conditions. Load capacity Two 86 class locos can pull a train weighing up to 1530 tonnes in the Blue Mountains section. (For downward trains from the western district, they can handle much heavier loads). This would be quite a long train, with somewhere between 30 and 50 wagons, depending on how heavily loaded they are. Such a train is longer than many a passing loop, so the trip from Penrith to Lithgow is run without stop, with the freight chased up the mountains by a lot of passenger traffic. In the afternoon, the Indian Pacific express leaves Sydney, followed by the evening peak traffic - two trains for Mt. Victoria and two for Lithgow, followed by "The Fish" and "The Chips". To ensure the fast freight loses no time with so many trains ALL EXCEPT ONE OF THE 50-strong 86 class are Co-Co machines (meaning 3-axle bogies). The exception is the 8650 shown here which is a Bo-Bo-Bo design with 2-axle bogies. The centre bogie moves sideways to allow the loco to follow curves. Such a design has improved ride and puts less side loading on the rails. "breathing down its neck", a third 86 class would be added at the head end. This is the maximum number of 86 class locos allowed on the one train between Penrith and Lithgow. On the heavy mountain grades the total current drawn by the three locomotives peaks at 8000A on starting, dropping to around 6000A when the train is underway up the long grades. This places an enormous load on the substations and catenary wires. No wonder these locomotives run with all pantographs up to collect such huge currents. No wonder too that both main and auxiliary catenary overhead wires are made of pure copper (different from the steel and aluminium used in other railways). Together with the cadmium copper contact wire, each track has three parallel conductors (ea tenary, auxiliary catenary and contact wire) with a total cross sectional area of 700 square millimetres. On stretches of track elsewhere it is possible to team as many as four 86 class locos together but there are limits on how they can be used. The first limit is dictated by the drawbar strength of the leading wagons while a second limit is the allowable voltage drop and current in the 108V DC control cables running through all four locomotives. Even then, say when hauling the heaviest trains on the Enfield to Kembla section of the Illawarra, only series or perhaps series-parallel notches of the controller are used to minimise current drain. On the Blue Mountains run, no more than three 86 class are used on trains up to 1530 tonnes with the locos starting in the series configuration and running in seriesparallel. The parallel notches are not used, a limitation set by substation and overhead wiring current capacity. Even so, three 86 class locos running in series-parallel and hauling 1530 tonnes of wagons can climb the mountain at speeds up to the limit imposed by the very sharp curves. These include the 241m radius curve near Glenbrook but there are others sharper still at 161m radius. To reduce sideways friction, the 86 class locos are fitted with flange lubricators. From Glenbrook to Katoomba the average grade is 3 % . For this stretch, the motors are run in the full series-parallel configuration. This is necessary to provide enough power on such heavy grades. Voltage drop The very heavy currents drawn by a trio of 86 class locos does cause a considerable variation in the catenary voltage. While it normally sits at about 1500V DC, it can drop to as low as 1150V, as shown on a meter on the driver's console. This does not cause any problems though. The train lights, controls and cab air conditioning will continue to function normally as they are all supplied from a 195kVA 3-phase 50Hz auxiliary alternator JULY 1989 85 THE 86 CLASS HAS A ONE-HOUR rating of 3328kW (4460hp) and a rated drawbar pull of 222kN (22 tonnes). However, it can exert a starting tractive effort of 420kN (42 tonnes). The loco weighs 120 tonnes with a full load of fuel and ballast. driven by a 200kW 1500V DC motor. Automatic solid state voltage and frequency regulators ensure that the auxiliaries are unaffected by line voltage variations. Regenerative braking The catenary voltage can not only drop to around 1150V or even lower but can also go quite high, even when a heavy train is running up the grade. This can be the normal result of a train coming down the grade under heavy regenerative braking. The huge currents so generated by the downhill train are not wasted in resistors as is done in most other rail systems. Instead, the regenerated current is fed back into the overhead line system to drive any train coming uphill. This relieves the trackside substations of a considerable load and saves millions of dollars in energy costs annually. There are very few railroads worldwide using such a money saving scheme. All other systems in Australia and most of those 86 SILICON CHIP overseas allow the train to drive its own motors as generators but simply dissipate all the current generated in high power resistors. This scheme is known as either "dynamic" or "rheostatic regenerative" braking. As long as the current generated by the downhill train is being used somewhere, it will experience a steady braking effect. This means that the air brakes are not needed except in an emergency stop, thus saving on wheel tyres and brake shoes. As a bonus, the brake shoes and wheels are cool when the air brakes are needed. Regenerative safeguards However there is still a problem. What happens if the train going up the mountain has to stop? What happens to all the current being generated by the downhill train? Is regenerative braking still available? The answer lies in the those huge 7.BMW convection cooled resistor banks installed outdoors at each mountain trackside substation. These resistors are automatically switched across the line whenever the uphill traffic is insufficient to provide braking for the downhill traffic. This condition is indicated if the substation DC voltage rises to 1820V DC due to the regenerative action of a downhill train. After allowing for voltage drop in the overhead wiring this corresponds to 2000V DC being generated by the downhill traffic. High current thyristors at each substation perform the necessary switching so quickly that the downhill driver is unaware of any variations in braking effect which would otherwise be caused by uphill trains stopping or slowing down. Electrification ends at Lithgow and from there on all trains are pulled by diesel electrics. By comparison with the 86 class electrics these are weak-kneed machines and nowhere near as energy efficient. Perhaps one day NSW will decide to greatly extend its track electrification and thus gain even greater use from its quiet, powerful, trouble-free 86 class locos. [§;;! Don't miss a single issue {c'" 'i :! Ji: r • Electronic house number .' .' ':i: 1 Convert a CB radio IF YOU'RE THE KIND OF READER that can't wait to get the next copy of SILICON CHIP, then why not have the magazine delivered direct to your door? Each month, we'll bring you the best and brightest electronics magazine in the business, put together by Australia's most experienced team. * * * * * * I I I I I I I I I I Hili review: Yamaha's brilliant new CD player Plus - the Original & ses.t iV ServieemM1 Vintage ~l:l~!o, The Way I Se& lt1 the- Evolution of Electric Amateur Radio The Serviceman's Log Vintage Radio The Way I See It Hifi Features & Reviews FREEPOST * SUBSCRIPTION COUPON □ □ New subscription Renewal Start in _ _ _ _ _ __ Name _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ (PLEASE PRINT) . 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Enclosed is my cheque/money order for$ _ _ _ or please debit my Detach and mail to: FREEPO'ST 25 SILICON CHIP PUBLICATIONS PO BOX 139 COLLAROY BEACH □ Bankcard NSW 2097 Card No. I □ $A120 □ Visa Card □ $A240 □ MasterCard I I I I I i I I I I I I I I I I Signature _ _ _ _ _ _ _ _ _ Card expiry date_ _ / __ /_ _ •No postage stamp required in Australia. l I L-------------------------------------~ JULY 1989 87 I PRODUCT SHOWCASE I 3-in-1 cordless tool has many uses This product has to be the answer to many enthusiasts' prayers. At some time or other everyone has the need of a cordless electric drill, a reversible power screwdriver and a soldering iron. Now there is this attractive package consisting of rechargeable battery pack in a pistol grip handle to whicH can be attached three modules: a two-speed electric drill, a power screwdriver and a solder- ing iron. These are clipped, bayonet fashion, into a red collar which is then rotated to lock it. The drill accessory has no-load speeds of about 5000 and 1000 RPM. Operating · speed is changed by twisting the front of the drill motor housing with respect to the rear section. It is fitted with a well made three-jaw key-type chuck which will take drills ranging from small number types up to 3.5mm in diameter. The screwdriver has a no-load speed of about 140 RPM and is Rugged horn speaker for PA work Some of the cheaper horns for PA work have spun anodised aluminium or plastic horns. This 10 watt Redford model is well finished in hammertone enamel and has an adjustable mounting which can be clamped at any angle. Nominal horn diameter is 20cm and maximum sound intensity at rated power is 1 lOdB. Removing the rear cover gives access to the line transformer which can be set to one of five different power levels from 1.25 88 SILICON CHIP reversed by changing the position of the locking collar. It has a hex drive socket which will take all ¼-inch screwdriver bits although it needs a short plug inserted to stop standard bits from sinking too far into the socket. In use the screwdriver has about the right speed and good torque for nipping up screws tight. The soldering iron is quite a useful unit with a very small tip and rating of about 20 watts so that it heats up within about 20 to 25 seconds. There is small light near the tip which illuminates the job to be soldered quite well. At a pinch it could also be used as a torch although it would not be an efficient use of the battery. Supplied with the package are four drills bits, four screwdriver bits, the chuck key, a hex key to change the soldering iron tip, some solder and a small sponge to clean the soldering iron tip. All of these fall out of the accessory wallet the first time you go to use them, after which you'll wrap it securely with a rubber band to stop it happening again. Also supplied is a plugpack charger which takes from 14 to 16 hours to fully charge the battery pack. At $99 from all Dick Smith Electronics stores, this unit (Cat. T-5712) is sure to be a big seller. Desoldering tool from Altronics watts to 10 watts. The unit is available from Altronics (Cat. C-2027) and their listed dealers at a recommended retail price of $69. Two larger versions with higher ratings are also available. One problem with using a conventional desoldering tool is that you need two hands to do the job as well as another hand to support the board. With this heated desoldering tool you only need one hand to do the job: apply the heated tip to the joint and then you press the button on the side to release the springloaded plunger and suck up the solder. It can also be used in a pinch as a conventional soldering iron. Removing the solder reservoir for Polystyrene capacitors YES Made here in Australia? YES Made Special to Type? YES Where From? Allied Capacitors Australia Allied Capacitors Australia specialises in custom made good quality, high stability polystyrene capacitors. Why design circuitry which requires additional components to achieve a specific capacitance; we can wind exactly the capacitance you need to match your design criteria within the ranges of 1 0pF to 1µF and up to 1 0,000VDC. Capacitors are manufactured to 0.25% , 0 .5%, 1.0%, 2 .0%, 2.5% , 5 %, 10% and 20% and are priced according to tolerance . All capacitors are tested to 2 .5 times the rated voltage. cleaning is easy and is just a matter of pushing down on the depressed plunger and then levering the assembly outwards - it is easier to do than describe. Recommended price of the desoldering tool (Cat. T-1250) is $59.50 from Altronics and their dealers. This month though, the tool is on special from Altronics at $49.95. CD cleaner from Philips Interested? Call us now on: (02) 938 4690 OR Cut out and post this coupon to ~oo~~~ r---------l Yes, I am interested in your capacitors. I Please post me details of the following values: I ... /... VDC . . . / ... VDC ... / ... VDC ... / ... VDC I Name I~ I (Please print) · ~B_r_o_o_~_a_1e_,_N_._a_w_._2_1_o_o___ L~~~~ ~~~~~~~J unit wet cleaning system which is claimed to have a radial cleaning action, from the centre of the disc to the outside edge. The Auto cleaner uses a chamois pad for the disc wiping action and is powered from an internal battery or an optional plugpack DC adaptor. Recommended retail price is $49.95. Shrink sleeving does not need hot air Everyone knows that CDs are easy to use and should last a lifetime but they do need to be kept clean. The only trouble is, how do you clean them while making sure that scratches are kept to an absolute minimum? Philips now has an answer in the form of their SBA 2 3 7 CD Autocleaner. This is a motor driven This new air shrinkable sleeving does away with the need for a hot air gun - it shrinks once it is removed from the container. It does so in a controlled fashion with 90% of the ultimate shinkage occurring in one hour. Airshrink is a rubberised PVC based tubing which is normally kept out of contact with air under an oily solvent in a sealed can or sachet. The oily solvent evaporates when exposed to the atmosphere, causing the shrinkage. Airshrink is available in dia- meters from 1mm to 60mm in red, blue, black and white. For further information, contact Airshrink Products Australia, 29 Royal Street, East Perth, WA 6004. Phone (09) 221 2764. JULY 1989 89 Test equipment for industrial applications Super£ast modem from Netcomm These days any modem that cannot cope with a speed of 2400 baud is pretty much of a yawn but here is a new unit from Netcomm that will blow a 2400 baud unit into the weeds. Called the Smartmodem M5, it has a top speed of 9600 baud while still being able to communicate at 2400, 1200, 1200/75 (Viatel) or 300 bits/sec. The Smartmodem M5 incor- porates several security features such as password access and dial back, together with full error protection. It also has full compliance with CCITT and Bell specifications. Software control is via the expanded Hayes AT command set and the Netcomm Program communications software is included in the purchase price. For further information, contact Netcomm (Australia) Pty Ltd, PO Box 284, Pymble, NSW 2073. Phone (02) 888 5533. if ' _.., ,,,i,id '#Jllll ';..d SC- ·~]~J .,·. y),\.\\\ · rrr A full range of meters is now available for industrial and scientific measurements. They range from basic indica tars to microprocessor based instruments for the measurement and control of pH, temperature, conductivity, pressure, weight, flow, RPM, current and many other specialised parameters. For further information, contact the manufacturer, Amalgamated Instrument Co Pty Ltd, Unit 7/21 Tepko Road, Terrey Hills, NSW 2084. Phone (02) 450 17 44. Large plastic instrument case t 'TI''J"t.L, New keyboard has trackball instead of a mouse A lot of software these days gives you the option of using a mouse to operate the cursor and select items or operations from an on-screen menu. The problem with a mouse is that it takes up valuable desk space which can be real a problem if your desk gets as cluttered as ours. One solution is to use one of the new PC keyboards which incor90 SILICON CHIP porates a trackball. Mounted on the righthand side, it falls naturally to hand - we think a lot a people will prefer it to a separate mouse. In other respects the keyboard is pretty much a standard PC AT layout with 101 keys. Priced at $199 including tax, it is quite a lot less than the cost of separate keyboard and mouse. It comes with a 3-month warranty and a 14-day money back guarantee from Electronic Solutions, PO Box 426, Gladesville, NSW 2111. Phone (02) 427 4422. This large and well finished plastic instrument case could be used in quite a number of applications. It measures 351mm wide by 138mm high (including its integral moulded feet) and 350mm deep. It is quite cheap at $14.95 but there is a catch - there are no front or rear panels. These could be made from aluminium or timber. Quantities are limited, so contact Geoff Wood Electronics without delay. Phone (02) 428 4111. Philips infrared image converter Dimmer extension ctd from page 35 Want to see in the dark? This Philips infrared image converter valve, type XX1080, could be used as the basis of an infrared vision experiment. You will need a lens system and a high voltage power supply. The tube is bargain priced at only $45 from D. Dauner who has all the data you need. See him at 51 Georges Crescent, Georges Hall, NSW 2198. Phone (02} 724 6982. 4.7MO and lMO resistors and functions in the same way as the touch plate during normal operation. If the Dimmer does not function, measure the DC voltage between pins 1 and 7 of ICl. The voltage should be close to 5V with pin 1 positive with respect to pin 7. If you can't measure this voltage, check the orientation of ZDl, D4 and the lOOµF capacitor. Don't worry about measuring the voltage across ZDl. If you do so, you will get a reading of about 2.5 volts which may suggest that ZDl is malfunctioning but it is not. If you get the right DC supply voltage and the Dimmer fails to function, check the polarity of Dl and D2. If you suspect that the Triac is faulty, you can easily check it by disconnecting D3 and then connecting a 1000 resistor between its A2 and G(ate) pins. This should light up the lamp while ever the 1000 resistor is connected. Don't do this For test while D3 is connected otherwise you run the risk of damaging ICl. You can also check the operation of the Extension input by momentarily connecting a jumper lead between the Active and Extension input. This duplicates the function of the touch plate. Remove the clip lead before reapplying the mains once you have the unit operational. ·1c Bookshelf - ctd from page 47 (shortwave listeners). Chapter 5 is on transceivers while chapter 6 gets into the nitty gritty of low band DX operation. Chapter 7 has Basic listings of computer programs discussed throughout the book. Chapter 8 is a comprehensive bibliography on all the topics in the first 6 chapters. This most useful book is available at a bargain price of $12 from the NSW Division of the Wireless Institute of Australia, PO Box 1066, Parramatta, NSW 2124. I~ RANGE .. . TECHNOLOGY ... and SERVICE TALK TO THE SPECIALISTS ABOUT YOUR BATTERY REQUIREMENTS! - BROADCASTING TEST EQUIPMENT HOBBY ELECTRONICS MEDICAL PROTOTYPING BATTERIES TO SUIT - BP90, NPI, ECLAIR , AARTON, ZENITH , AMPEX , FREZZOLINI. BATTERY PACKS TO SUIT MOST OE TEST ANO MEASUREMENT REQUIREMENTS. - SPECIALIST TYPES TO SUIT MOST APPLICATIONS. - MEMORY SUPPORT IN BOTH LITHIUM CELLS ANO NICKEL CADMIUM, ALSO PCB MOUNT. - BATTERY PACKS FOR - OATASCOPE, IVAC, LIFEPAC, BIOMECCA, MEOTEL, SONICAID, HOLTER, HP, MINOLTA, NIKON. - TALK TO PREMIER FIRST. LITHIUM CELLS NICKEL CADMIUM CELLS (SMALL SIZE HIGH CAPACITY, LONG SHELF LIFE) (RAPID CHARGE, HIGH CAPACITY) CUSTOM SERVICE AVAILABLE FOR ALMOST ANY BATTERY APPLICATION: CALL PREMIER NOW! PREMIER BA'l"l'ERIES PTY LTD Unit 7, 27 Childs Road , Chipping Norton, N.S.W. 2170, Australia Tel: (02) 726 7701 Telex : AA72524 Fax: (02) 727 0565 JULY 1989 91 ASK SWCON CHIP Got a technical problem? Can't understand a piece of jargon or some electronic principle? Drop us a line and we'll answer your question. Write to: Ask Silicon Chip, PO Box 139, Collaroy Beach, NSW 2097. Hard to obtain EHT tranny Some time ago I was given a Princess model 14CT2 portable colour TV that was not working. After a little investigation I discovered a charred wire coming from the EHT transformer. The winding it was coming from provided the initial excitation pulse via a diode to activate the power supply. There was sufficient slack in the wire to effect repairs and get the set working again after which it ran for the best part of two to three years without any problems. Now the set has failed again, this time with a similar problem. The EHT transformer in this set has a separate EHT winding connected to the picture tube via a diode stack. The winding in question has a number of wires entering it and, at the point where they all come together at the base of the winding, they have charred and fused. This winding is set in epoxy and cannot be repaired. I have been in touch with the Princess Service Centre who have supplied advice on an alternative EHT transformer (modified) from a Toshiba set. As both these sets are now relatively old, I have had no luck in procuring a transformer, as neither company still holds stocks. Can you please suggest any way of modifying alternative (current model) transformers or can you provide any other suggestions on alternative EHT supplies? (D. T., Bradbury, NSW). • It is unlikely that you will be able to purchase an EHT transformer for this set, although it is possible that the transformer used in the Princess l4CT6 may suit. We checked this point with our Serviceman and he noted that if such a transformer is found it is likely to be expensive. The last one he pur- chased, two or three years ago, cost $125. In addition, this may not be the only fault in the set. The EHT transformer may have failed due to another fault and the cost and difficulty of repairing this would have to be allowed for. You may be better off junking the set. Confusion over amplifier ratings Congratulations on a very fine electronics magazine. I read your article on the 50W and 100W amplifiers described in the December 1987 issue with much interest but have a few enquiries before I purchase a kit. In the magazine article you feature 50W and 100W versions but Altronics have a kit which puts out 150 watts into a 40 speaker. Was this version designed by SILICON CHIP or is this Queries on the Off Hook Indicator and Speakerphone In the Off Hook Indicator published in the November 1987 issue of SILICON CHIP, there is an error in the Veroboard overlay shown on page 68. The 470k0 resistor which is physically between the IC and ZD2 is shown connecting from the positive rail to pin 4 whereas the circuit shows it connecting to the base of Ql. As built, the unit would not work but repositioning the resistor corrected the problem. One point worth noting is that when a phone is on hold, the light does not work. This is because the hold voltage is about 25V and therefore too high for the circuit to sense (however most phones will not hold indefinitely but cut out after about 5 minutes). Another point is that the LED flashes when the phone rings. 92 SILICON CHIP Having studied the Australian phone system and compared it to the New Zealand system (an extra wire provides the bell ringing voltage), I am not sure whether all your projects will necessarily work in NZ (particularly the Line Grabber). However, given the similarities, I would like to know if the Speakerphone (published in the September 1988 issue of SILICON CHIP) will work. I recently constructed a Jaycar kit of the FM Stereo Transmitter (SILICON CHIP, October 1988) and found it to work very well, with one small proviso: the trimmer capacitor is a polarised component and must be inserted the right way around. As constructed, I had installed it rotated 90° clockwise to its correct position and it would not perform its stated function. Close examination of the photographs showed up my mistake. Reinserting it the right way in fixed that problem. The unit gives good sound over about 30 metres (in stereo) with an aerial which is a piece of wire 80cm long. (P. D., Christchurch, NZ). • Thanks for the comments on the Off-hook Indicator and the FM Stereo Transmitter; you are right about the mistake on the Veroboard. As far as we can determine, both the Line Grabber (SILICON CHIP, March 1988) and the Speakerphone should work without modification on the NZ telephone system. just to fool people who don't know much about electronics? I would like to use the amplifier to run 12 speakers. ls this possible with any of these versions? I know that if I connect two 80 speakers in parallel the total load will be 40 and if I connect two 40 speakers in series the total load will be 80. Does this mean I can only run two speakers off each amplifier? Would I have to build six amplifiers to run 12 speakers? I would like to run 100W speakers. Does it also mean that I have to run two 50W speakers so the total power is lOOW? Also I would like to be able to have a volume control for a number of speakers so the volume can be controlled in each of the rooms and the sheds. Would it also be possible to have a microphone set up with the amplifier? If it's not too much to ask, could you please publish an article on crossovers? I would like to know what they are, what they are used for, how they work and how to construct them. (M. A., Renmark, SA). • The Altronics amplifier in question is our 120W amplifier as described in November and December 1988. You can use as many speakers as you like with any solid state amplifier as long as the load impedance is not less than the rated load for the amplifier. We're not sure what you wish to achieve with your connection, though. If you wish to run 12 speakers in total or 6 per channel, you could use a series parallel arrangement so that you had 3 parallel strings of 2 speakers in series. This would give a load impedance of 5.30 which would be quite permissible. However, that means that the maximum power from each channel of the amplifier is divided by 12, as far as each speaker is concerned. With a 100W amplifier module, each speaker would get a maximum power of 8.3 watts. On that basis, there is little point in using speakers rated at 50 or 100 watts. The fact that you want to run speakers in a number of rooms and sheds, volume controls on each speaker and a microphone means that a conventional stereo power TV sound receiver for the partially deaf I have recently started teaching myself electronics and I have found your publication to be the best available at present. Keep up the good work. A friend of mine has a slight hearing defect and, although not a major problem, this creates difficulties when listening to television. I would like to know whether you could supply a circuit diagram for a VHF audio receiver which would be capable of receiving all TV signals. A modified portable FM radio receiver might be the go. The circuit needs to have a volume control and be capable of reasonably high output. The circuit also needs to have a tone control which would be required to reduce the lower signals as these are muffling the overall sound that this person is hearing. The unit would also need to have an external antenna as used on some transistor radios. Output would be through stereo earphones as aTe commonly used with portable radios and tape players. (M. S., Capalaba, Qld). amplifier is not a practical proposition. You really want a public address amplifier with a 100V line output. That being the case, you would be better off having a look at the 120W module referred to above or the complete PA amplifier described in the December 1988 issue. Suitable speaker volume controls for this amplifier are stocked by Altronics (Cat. A-2330 etc). Compressor for TV commercials I notice in the magazine that you invite suggestions for articles, so here are a couple. I would be interested in a project for a house burglar alarm centred around a passive infrared detector, keeping the cost as low as possible. I do not think this has been done in a local electronics magazine. I know that the necessary equipment, such as the relay for the siren • The problem with a TV sound receiver is that if such a circuit was to be universal, it would not only have to cover the VHF television band, it would also have to cover UHF. That means it would need two tuner modules which would add to the expense. As we see it, designing such a project from the ground up would not be viable. You have two alternatives. First, you could take the audio signal from a standard VCR (which will tune both the UHF and VHF bands) and feed it to our FM Minimitter circuit published in the October 1988 issue of SILICON CHIP. You could then use any FM portable or W alkman style receiver to listen via headphones to the TV sound via the FM band. Alternatively, if you don't need the UHF TV band, you could consider going for Tandy's Realistic Pocket Portavision radio. This picks up the AM and FM bands plus the sound from TV channels 2 to 11. It is priced at $49.95 (Cat 12-613) and could be the simplest and best solution. and a timing device for shutting off the siren etc, can be bought in a fancy metal box for $150 plus but I am thinking along the lines of a large jiffy box or similar. Secondly, I am getting on in years and the high frequency end of my hearing is well down, perhaps more than usual. The result is that I find it hard to understand speech out of the TV speaker, no matter how loud. A great improvement can be obtained by using phones with a 0. 11,lF capacitor in one leg. The capacitor apparently attenuates the bass component of the speech and my ears can understand it better. The only trouble is when theme music or commercials come on and the decibels go sky high. Would it be possible to build something along the lines of the CD Compressor (March 1989} but to be used in the sound output of the TV. This would also be beneficial to ]ULY 1989 93 Substitution guide for transistors Sorry about this, but you did stick your neck out by asking for suggestions which might enhance your excellent monthly publication. I suggest, and I know it is very near an impossible task, that you gather together some sort of "Ready Reckoner" for hobbyists to be able to select a possible replacement or substitute transistor for the usual one they can't get from any known source - always the case, these days. I can envisage all sorts of problems over copyright infringements etc in such an endeavour, but surely any large combines concerned could only increase people listening to the speaker, to alleviate the yelling which accompanies most commercials. (M. B., Toukley, NSW). • Your suggestion for a house burglar alarm is a good one. We agree that metal boxes can be expensive but jiffy boxes are not really the go either. These days you need back-up batteries and the alarm needs to be lockable so it can't be easily tampered with. As far as TV sound is concerned, we agree that commercials can present a big problem when they come in so loud. Unfortunately though, the CD Compressor is not the answer. Building it into a modern TV set would not be a good idea as they have a live chassis. The only really effective answer to blaring commercials is to have a remote control which enables you to zap them off. Problems with PL-259 connectors Could you tell me where to obtain a 1000 or 2000 carbon pot? Secondly, do you have any tips or methods of soldering PL-259 connectors to coax cables? I spend quite some time in experimenting with antennas and feed lines in the amateur HF bands and as a consequence 94 SILICON CHIP sales by this enterprise. I realise that a lot of this information is available at the moment but at prohibitive cost to all but the biggest of operators. Surely a limited edition of substitutes for semiconductor devices as used in equipment as sold through retail outlets over the last 15 or 20 years could be compiled. Perhaps the manufacturers could be persuaded to help by providing their m,vn lists of currently available substitutes. It would save you doing the research. I'm right with you and understand that the tendency today is toward the "throw-away" mentality, even to the extent of using one-way screws which I came across recently. have built several RF bridges to aid in this work. However, the major problem is in obtaining a linear carbon potentiometer of 1000. While 5000 and 10000 pots are readily available they do not give sufficient accuracy on a calibrated dial below 750 to observe the dips on resonance. I do possess a noise bridge but find that a simple RF bridge in conjunction with a GDO (grid dip oscillator) finds the resonant frequency much quicker; I can then use the noise bridge for confirmation and double checking. When soldering PL-259 connectors onto coax cables I find my main difficulty lies in the final soldering of the coax sheath to the shell of the PL-259 via the four small holes in the shell. I have even tinned the edges of the four holes before starting but still cannot avoid sometimes overheating the whole shell and consequently getting a partial melt of the coax. It would appear to me that you must have some form of instantaneous high heat application in the area of the soldering holes sufficient to run the solder without conduction of the heat to a temperature that will damage the cable. Any thoughts on this one please? Keep up the good work on SILICON CHIP; I thoroughly enjoy it To get back to the point, I have a HMV portable TV (Model 45556) which is some 15 or 20 years old. It appears that the regulator transistor is open circuit emitter to base. The tansistor is marked C1568-R and I have not been able to find a supplier who has a replacement item. Can you help? (S. S., Sandgate Qld). • You know not what you ask. We have a number of books for transistor substitutions and one lists no fewer than 27,000 transistors. Unfortunately, the one you want is not listed. Can you tell whether the failed transistor is NPN or PNP? If it is NPN, we suggest you use the readily available BD139. If PNP, then use BD140. and maybe the above can give you some ideas on antennas and feedlines and the necessity to get it right if you want maximum transmission and reception efficiency. (J. B., Broadmeadows, Vic). • You may be able to get 100 or 200 ohm carbon pots from D. Dauner at 51 Georges Crescent, Georges Hall, NSW 2198. Phone (02) 724 6982. Alternatively, you might try Oatley Electronics, PO Box 89, Oatley, NSW 2223. Phone (02) 579 4995. As far as soldering PL-259 connectors goes, we agree that these connectors are very difficult to solder and we really don't know why they remain so popular. The only thing we can suggest is that you use a temperature-controlled iron with a small tip. Apart from that, we don't have any particular clues. Have you thought of using BNC plugs and sockets instead? You could also use a PL-259 plug to BNC socket adaptor. After all, BNC sockets are now widely used on RF transceivers these days. We understand too that BNC plugs and sockets give a better SWR, particularly at the higher frequencies. Alternatively, why not use solderless PL-259 plugs. These are easy to use and are readily available (eg, from Tandy). ~ December 1987: 1 OOW Power Amplifier Module; Passive lnfrared Sensor; Universal Speed Control and Lamp Dimmer; 24V to 12V DC Converter. February 1988: 200 Watt Stereo Power Amplifier; Deluxe Car Burglar Alarm; End of File Indicator for Modems. March 1988: Remote Switch for Car Alarms; Telephone Line Grabber; Endless Loop Tape Player. April 1988: Walkaround Throttle for Model Railroads ; pH Meter for Swimming Pools; Slave Flash Trigger; Headphone Amplifier for CD Players. May 1988: Optical Tachom eter for Aeromodellers; High Energy Ignition for Cars; Ultrasonic Car Burglar Alarm. June 1988: Stereo Control Preamplifier; Breakerless Ignition For Cars ; MegaFast Nicad Battery Charger. July 1988: Fitting a Fuel Cut-Off Solenoid ; Booster for TV & FM Signals; The Discolight Light Show. August 1988: Plasma Display; Remote Chime/Doorbell; High Performance AC Millivoltmeter; Getting the Most Out of Nicad Batteries. September 1988: Hands-Free Speakerphone; Switchmode Charger for 12V Gel Batteries; Vader Voice . October 1988: Stereo FM Transmitter; High Performance FM Antenna; LedLight House ·Number; Matchbox Crystal Set. November 1988: 120W PA Amplifier Module; Poor Man 's Plasma Display ; Car Safety Light; How to Quieten the Fan in Your Computer. December 1988: 120W PA Amplifier; Diesel Sound Generator; Car Antenna/Demister Adaptor; SSB Adaptor for Shortwave Receivers. January 1989: Line Filter for Computers ; Proximity Detector for Cars ; How to Service Car Cassette Players. February 1989: Transistor Beta Tester ; Build the Minstrel 2-30 Loudspeaker System; LED Flasher for Model Railways. March 1989: LED Message Board; 32-Band Graphic Equaliser; CD Compressor; Amateur Band FM Receiver. April 1989: Telephone Bell Monitor/Transmitter; Auxiliary Brake Light Flasher Circuit. May 1989: Electronic Pools/Lotto Selector; Synthesised Tom-Tom; Biofeedback Monitor For PCs; Simple Stub Filter For Suppressing TV Interference. June 1989: Touch-Lamp Dimmer; Passive Loop Antenna For AM Radios; Universal Temperature Controller; Understanding CRO Probes. Note: stocks of December 1987 & February 1988 are now very low. November 1987 and January 1988 are now sold out_ ~ .---------------------------------- + --7 Use this handy form to order your back copies Please send me a back issue for: □ December 1 987 □ February 1 988 □ March 1988 □ April 1988 □ May 1988 □ June 1988 □ November 1 988 □ July 1988 □ August 1988 □ December 1 988 □ January 1 989 □ September 1 988 □ February 1 989 □ October 1 988 □ March 1989 □ April 1989 □ May 1989 □ June 1989 Enclosed is my cheque/money order for $ _ __ _ _ _ or please debit my Signature _ _ _ __ _ _ _ _ _ Card expiry date_!_ _ / _ _ Name _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ (P LEASE PRINT) Stree~-----------------------Suburb/town _ _ _ _ _ _ _ _ _ __ __ Postcode____ D Bankcard D Visa Card D MasterCard Price: $A5.00 each (includes postage). Overseas orders add $A 1 .00 per issue for postage. NZ & PNG orders are sent by air mail. Detach and mail to: SILICON CHIP PUBLICATIONS PO BOX 139 COLLAROY BEACH NSW 2097 ~-------------------------------------~ ]ULY 1989 95 CEN Cash in your surplus gear. Advertise it here in Silicon Chip. CLASSIFIED ADVERTISING COUPON Advertising rates for this page: Classified ads - $7 .00 for up to 15 words plus40 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 cann ot accept ads submitted without this information. To run your own classified ad , put one word on each of the lines below and send this form with your payment to: Silicon Chip Classifieds, PO Box 139 , Collaroy Beach , NSW 2097. PLEASE PRINT EACH WORD SEPARATELY, IN BLOCK LETTERS 2 3 4 5 6 7 8 9 10 11 12 13 14 15 ($7.00) 16 ($7.40) 17 ($780) 18 ($820) 19 ($8.60) 20 ($9 .00) 21 ($9.40) 22 ($980) 23 ($10 20) 24 ($1060) 25 ($11 00) 26 ($11 .40) 27 ($11 .80) 28 ($12 20) 29 ($12 60) 30 ($13 00) Name. PC Boards Address ... Postcode Suburb/Town Enclosed is my cneque or money order for$ ........................... ......... or please debit my Bankcard D Visa Card D MasterCard D Card No I I . .. ..Card expiry date .. .... . / ..... ../. . Signature FOR SALE 1M PRINTER BUFFER KIT. Rev H boards now available. Supports 8K to THE HOMEBUILT DYNAMO by Alfred T. Forbes ISBN 0-9597743-0-4 Reviewed in S.C. October, 1988. $A85 including air mail post. (Brochure $AS refundable) Trade enquiries welcome. Todd-Forbes Publishing, PO Box 3919, Auckland 1, New Zealand. 96 Advertising Index Allied Capacitors ... 89 Altronics . . . . 24-27 Arista Electronics 19 CompuHelp Australia . . IFC Dauner Electronics 31 David Reid Electronics . .. 3 Dick Smith Electronics 36-4 1 Electronic Solutions 56-57 Elmeasco OBC Esckay Printernet . . . . 81 Geoff Wood Electronics .... 65 Hycal Instruments ...... .. 31 Jaycar Electronics 48-51 74-77 J.V. Tuners .... 53 Oatley Electronics . . . 73 PC Marketplace . . 12-13 Premier Batteries . . 91 RCS Radio . . . . . . . . . . . . . 7 3 RF Devices . . 21 Rod Irving Electronics IBC Technikit Electronics . 23 WIA 68 SILICON CHIP 1M. $39 kit consists of double sided PCB, EPROM and instructions. Optional additions include 2 by 7 -segment LED front panel display of percentage full, 1 to 99 copies select, 3 polled computer inputs, printer switches, computer switches and serial converter boards. For a free catalog send a 39c stamp to Don McKenzie, 29 Ellesmere Crescent, Tullamarine 3043. MONITOR: COMMODORE green screen. Hi-res TTL input. New in box. $110. Phone (02) 670 3700 . RADFAX 2 WEATHER fax, Morse and RTTY receive program for IBM PC/XT/AT on 360K 5.25-inch floppy plus full documentation. Needs CGA, Printed circuit boards for SILICON CHIP projects are made by: • RCS Radio Pty Ltd, 651 Forest Rd , Bexley, NSW 2207. Phone (02) 587 3491. • Jemal Products, 5 Forge St, Welshpool, WA 6106. Phone (09) 350 5555 . • Marday Services, PO Box 19-189, Avondale , Auckland, NZ. Phone 88 5730 . SSB HF, FSK/tone decoder. Has realign, auto-start, view, save, print. Also "RF2HERC" same as above but suitable for Hercules card and "RF2EGA" for EGA card (640 x 350 mode). Programs are $35 each plus $3 postage. Only from Michael Delahunty, 42 Villiers Street, New Farm, Qld 4005. Phone (07) 358 2785. SERVICES HI-TECH STEREO AMPLIFIERS built. Reasonable prices. For full details send SAE to 36 Palmer St, Nambucca Heads, 2448 . r----------, I ROYEL SOLDERING STATION I I I I I II LOGIC PULSE (LP-540H) • Can be used directly to inject a signal into logic circuits without removing IC • Compatible with TTL, DTL, RTL HTL, MOS and CMOS ........ 011274 .................. $49.95 All sales tax exempt orders and wholesale inquiries to: RITRONICS WHOLESALE : 56 Renver Road, Clayton. Phone:(03) 543 2166 (3 lines) Fax: (03) 543 2648 SYDNEY: 74 Parramatta Rd. Stanmore 2048 Phone: (02) 519 3134 Fax: (02) 519 3868 MELBOURNE: 48 A'Beckett St Phone: (03) 663 6151 NORTHCOTE: 425 High St. Phone: (03) 489 8866 ADELAIDE : (Electronic Discounters) 305 Morphett St. Adelaide Phone: (08) 212 1799 MAIL ORDER& CORRESPONDENCE: P.O. 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 ORDER HOTLINE 008 33 5757 (TOLL FREE) STRICTLY ORDERS ONLY LOCAL ORDERS & INQUIRES (03) 543 7877 POSTAGE RATES: $1 • $9.99 ......................... $2.00 $10 • $24.99 .....................$3.00 $25 • $49.99 ..................... $4.00 $50 • $99.99 ..... ............... .$5.00 $100 + ..............................$7.50 The above postage rates are for basic postage only. Road Freight, bulky and fragi le items will be charged at different rates. Errors and omissions excepted. Prices and specifications subject to change. IBM' , PC", XT' , AT" . are registered trade marks of Inte rn a tion al Bus iness Mac hin es . ' Appl e 1s a regi st ered tr ad ema rk . ' Deno n te s reg iste r e d trademarks et their respective owners [E B] VISA • Aux ground connection • For soldering ironsCT6 (3mm Tip), CT7 (5mm Tip) T $ 12570•• · •••• ••• ... .. .. 195 1 I 1 I I I I • Instantly shows the open/short position of PCB's • It can test whether PCB's or solid wires are, short or open by buzzing 011276 .................. $22.95 :r:1:e RODIRVING ELECTRONICS The all solid-state heat sensor and control unit allows the selection of the appropriate soldering tip idling temperature. The very high-powered element (relative to the size of the tool) will replenish heat drained from the tip during each soldering operation and will recover the tip tempreture moments after = the tip is lifted. • Zero voltage switching • Zero tip potential . BRAND NEW WIRE WRAP WIRE DIGITAL METER • Autoranging operation • Data-hold for easy readout • Full range protection • 0-500 volts AC-DC • 0-20 Mn • Dimension & weight =133 x 29 x 17mm and 60g approx 011270 ....................... $69 MULTIMETER (YF-100) •Precut wire per packet of 100 W19002 Blue 3.0" ....... $4.75 W19022 Red 3.0" ....... $4.75 W19042 Yellow 3.0" ....... $4.75 W19062 Black 3.0" ....... $4.75 W12784 Green 3.0" ....... $4. 75 W19026 W19046 W19066 W12790 W19006 Red 5.0" ....... $5.95 Yellow 5.0" .......$5.95 Black 5.0" ..... .. $5.95 Green 5.0" ....... $5.95 Blue 5.0" .......$5.95 W19016 W19036 W19056 W19076 W12796 Blue 10.0" .....$10.50 Red 10.0" ..... $10.50 Yellow 10.0" ..... $10.50 Black 10.0" ... .. $10.50 Green 10.0" ..... $10.50 • Autoranglng tor DCV, ACV, OHM & continuity measurement · • 10mm thickness & 80g light weight tor easy operation • Drop proof of any Incidental tall-off • Dimension & weight.= 108 x 54 x 8mm and 60g approx • Large display 4 1/2 dgt 0.5" height LCD with maximum reading of 19999 • Automatic polarity."-" display tor negative input • High over-load protection for all ranges • Over load display, the highest digit "1" or "-1" alone glows • Power consumption 20mW approx. • Dimension & weight= 162 x 86 x28mm and 200g approx Q11266 ..................... $199 MULTIMETER (YF-3000) • Large display 3 1/2 digit 0.5" height LCD for easy readout • Auto/manual range select easy to operate • Automatic low battery" - + " display tor battery indication • Memory-comparative function available for allowance within ±5%f.s • Warning sound tor overload and conductance • Dimension & Weight = 170 x 80 x 33mm, 260gram approx • Data hold function for easy readout 011268 ............... .. .... $110 W19416 W19417 W19420 W19425 W19426 W19427 W19428 W19430 W19435 Green 10011 ..... $10.75 Brown 10011 .....$10.75 Blue 10011 .... .$10.75 Red 10011 .. ... $10.75 Purple 10011 .. ... $10.75 White 10011 ... .. $10.75 Orange10011 ..... $10.75 Yellow 10011 ..... $10.75 Black 10011 .....$10.75 W19460 W19461 W19465 W19475 Blue Green Red Black 50011 50011 50011 500ft ..... $33.75 .. ... $33.75 ..... $33.75 ... .. $33.75 HEAT SHRINK TUBING JUMP WIRE KIT (KS-350) Contains: 14 kinds of length from 0.1" to 5" with different colors 011278 .................. $19.95 • Per metre PHS25 PHS20 PHS16 PHS13 PHS10 PHS 7 PHS 5.5 PHS 3.5 PHS 2.5 PHS 1.5 IBM * PC/XT WIRE WRAPPING BOARD H19117 .................. $59.95 BREAD BOARDS This inexpensive rang of modular interlocking units enables a quick, easy way of experimenting with new circuits and ideas. There are two main units consisting of a terminal strip or distribution and a Central plug-in unit. • 100 holes P11000 .................... $2. 75 "NEW" Q11264 ....................... $69 MULTIMETER (YF-2100) • Spool wire W19390 Green 5011 ........ $8.00 W19400 Blue 5011 ..... ... $8.00 W19406 Purple 5011 ........ $8.00 W19407 White 5011 .. ...... $8.00 W19408 Orange 5011 ........ $8.00 W1941 0 Yellow 5011 ........ $8.00 W19415 Black 5011 ........ $8.00 This is a halt size wire wrap board suiTable for research and development. • Standard IBM• Pc•txT• bus edge connector • Tinned plated through holes • 2.54mm spacing • 19.4cm x 10cm wire wrapping 25mm ............ $6.95 20mm ............ $5.00 16mm ............ $3.60 13mm ............ $3.30 10mm ............ $2.65 7mm ..............$2.15 5mm .............. $1.85 3.5mm ........... $1.70 2.5mm ........... $1.50 1.5mm ........... $1 .30 • 640 + 100 holes P11007 .................. $14.95 • 1280 + 100 holes P11010 ..................$26.95 LOW PROFILE IC SOCKETS NUMERIC KEYPAD Unencoded keypad, 10 digit keys plus two utility keys. Light grey in colour. C19030 1-9 10+ 100+ $2.95 $2.50 $1.95 Save a small fortune on these "Direct Import" low profile le sockets! PCB mounting solder tail. All tin plated phosphor bronze or berryllium and dual wipe tor reliability. Cat. No. Description 1-9 10+ P10550 8 pin ........... $0.20 $0.15 P10560 14 pin .......... $0.25 $0.20 P10565 16 pin ......... $0.35 $0.20 P10567 18 pin ......... $0.40 $0.30 P10568 20 pin ......... $0.40 $0.30 P10569 22 pin ......... $0.40 $0.30 P10570 24 pin ... .... .. $0.40 $0.30 P10572 28 pin ...... .. . $0.50 $0.40 P10575 40 pin ......... $0.50 $0.40 r suPERFASTI>YNAM IC-1 I II I ■ L • RAMS .. I II 4164-150ns ............................... $4.25 4464-150ns ........................ ... .. $17.85 41256-S0ns ................... .. ........ $14.95 I 41256-100ns $14.30 _ _ _ _........................... _____ _ ..J■ FLASHING LEDS • Red, 5mm 1-10 210159 $1.10 10+ $1.00 ~--- 9=_,_ QUALITY LEDS Cat. no. 210140 Description Price 3mm Red ........ $0.15 210141 3mm Green .... $0.20 210143 3mm Yellow .... $0.20 210145 3mm Orange .. $0.20 210150 5mm Red ........ $0.10 210151 5mm Green .... $0.15 210152 5mm Orange .. $0.15 210155 10mm Red ......$1.00 210156 10mm Green ..$1 210157 10mm Yellow .$1.00 .00