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Polychlorinated Biphenyls by Marque Crozman They could be present in your home 22 Win A Bose Lifestyle Music System Take out a subscription and you are in the draw 38 The Bose Lifestyle Music System by Leo Simpson A closer encounter with this radical new hifi system 94 The Story Of Electrical Energy, Pt.4 by Bryan Maher High voltage transmission lines 4 Da,-ger - PROJECTS TO BUILD 24 Build The Surfsound Simulator by Darren Yates It produces the soothing sounds of the sea HERE'S A REALLY loud siren that will wake the dead - well, just about. Find out how to build it by turning to page 48. 48 Low Cost Siren For Burglar Alarms by Leo Simpson A compact siren to wake the dead 66 DC Offset For Digital Multimeters by John Clarke Gives you greater resolution for monitoring voltage drift 72 Dimming Controls For The Discolight by John Clarke Add manual fade to all four channels ,-y~-- SPECIAL COLUMNS 16 Vintage Radio by John Hill The different types of radio valves 52 Serviceman's Log by the TV Serviceman If only I'd known all the symptoms 82 Amateur Radio by Garry Cratt Using the NE602 in home-brew converter circuits 87 Computer Bits by Jennifer Bonnitcha What's gone bung now? 110 Remote Control by Bob Young The adverse effects of dihedral on aerobatic aircraft t-1\'-f w~s A C'RO WHEN THE SERVICEMAN gets in a jam, he brings up the heavy artillery. This month, he solves a sticky problem & talks about the change over to UHF in the Illawarru region of NSW. DEPARTMENTS I 3 Publisher's Letter 62 85 92 102 Circuit Notebook Subscription Page Mailbag Product Showcase 108 Back Issues 116 118 119 120 Ask Silicon Chip Notes & Errata Market Centre Advertising Index DID YOU BUILD the popular Discolight project? If so, you can now add manual fade to all four channels to increase its versatility even further. See page 54. 2 'BIG GUN SILICON CHIP PUBLISHER'S LETTER Publisher & Editor-in-Chief Leo Simpson, B.Bus. Editor Greg Swain, B.Sc.(Hons .) Technical Staff John Clarke, B.E.(Elec.) Robert Flynn Darren Yates Advertising Manager Paul Buchtmann (02) 979 5644 Mobile: 018 28 5532 Victorian Representative McDonald Woodside & Associates Pty Ltd, 1 43a Como Parade East, Parkdale, Victoria 3194. Phone (03) 587 5155. Contact: Cameron McDonald. Thank you for your enthusiastic response Well, what a response we've had to the reader survey in last month's issue. No sooner had the issue hit the streets than the surveys started pouring in. We are delighted with the enthusiasm that readers have for SILICON CHIP. And what have the surveys shown us so far? As I write it is much too early to draw any concrete conclusions from the survey - that will have to wait until all the results are entered into a computer and a statistical analysis is produced. However, there are some interesting observations that can be made at this early stage. The first is that a surprising proportion of readers responding to the survey have access to a fax machine - ours has been running hot. Second, a very high (somewhere in the vicinity of 90%) proportion own a computer. We thought that quite a few of you did own a computer but we did not dream that the proportion was that high. Many readers own more than one computer. Oh, and those that own Apple Macintosh's reckon that the PCs came out of the ark - they hate 'em. Funnily enough, those that own PCs don't express similar opinions about opposing brands - perhaps they don't know any better, eh? More than that we can't really say. Our readers appear to evenly span the age range between teen age and retiring age, are well educated and express very strong opinions about what they like and dislike in terms of magazine content. There have also been lots of good suggestions for magazine articles and projects - plenty for us to stew over in the months to come. Thanks for the enthusiastic response. It's great. And now I draw your attention to an article in this issue which we feel is particularly important - the one on PCBs. Many people in the electronics industry have been casually exposed to PCB capacitors in the past and probably don't think about it at all. Well, they are a nasty environmental hazard and we should do all we can to make sure that the contents of PCB-impregnated capacitors don't eventually cause pollution. Have a read of the article so that you know what to do when you come across them. See you next month. Leo Simpson Regular Contributors Brendan Akhurs1 Jennifer Bonnitcha, B.A. Garry Cratt, VK2YBX John Hill Jim Lawler, MTETIA Bryan Maher, M.E., B.Sc. Jim Yalden, VK2YGY Bob Young Photography Glen Cameron Editorial Advisory Panel Philip Watson, MIREE, VK2ZPW Norman Marks Steve Payor, B.Sc., B.E . SILICON CHIP is published 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. Typesetting: Magazine Printers Pty Ltd, Rozelle, NSW 2039. Printing: Macquarie Print, Dubbo, NSW 2830. Distribution: Network Distribution Company. Subscription rates: $42 per year in Australia. For overseas rates, refer to the subscription page in this issue . Liability: Devices or circuits described in SILICON CHIP may be covered by patents. SILICON CHIP disclaims any liability for the infringement of such patents by the manufacturing or selling of any such equipment. Editorial & advertising offices: Unit 39, 5 Ponderosa Pde, Warriewood, NSW 2102. Postal address: PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 979 5644. Fax (02) 979 6503. ISSN 1030-2662 OCTOBER 1990 3 What you need to know about polychlorinated biphenyls (PCBs) Up till now, whenever you've thought of PCBs, you've probably thought of printed circuit boards. But there is another more sinister meaning for PCBs - polychlorinated biphenyls. These are ·a type of oil which was widely used in the electronics and electrical industry about 15 years ago. By MARQUE CROZMAN Where can you expect to find PCBs? The answer is virtually everywhere. PCBs were used as the impregnating oil in huge numbers of AC capacitors up until about 1975. And where will you find these cantype AC capacitors? Most frequently in fluorescent light fittings but also in ceiling fans, dishwashers and in fact in any electrical appliances which used capacitor splitphase motors. The capacitors we are talking about generally have a value between 2µF and 16µF and are rated at 250V AC or 440V AC. They are housed in aluminium cans which may be flattened or cylindrical in shape, as shown in the photos in this article. The problem is that these capacitors all eventually leak. They may start to leak gradually, or they may fail catastrophically, spraying their hot contents over anyone in the room. When that happens, and it can happen at any time, you have big problems. There are tens of thousands of old buildings around Australia, many with a thousand or more fluorescent light fittings. This means that there are literally millions of PCB-filled capacitors waiting to leak, or spray their contents over people. Power factor correction The capacitors are installed in 4 SILICON CHIP fluorescent light fittings to correct their power factor. In simple language, a fluorescent light is largely an inductive load. The current in such a load "lags" the voltage and this causes losses in the power generation system, in transformers and in transmission lines. The cure is to connect a capacitor of a particular value in parallel with the light. Hence, all fluorescent lights in POISON commercial and public buildings, in factories, schools, supermarkets, workshops and so on have power factor correction capacitors in them. And if these capacitors were made before 1978 they are bound to contain PCB oils. In homes, the situation is a little different. Generally, domestic fluorescent lights do not contain power factor correction capacitors. However, in older homes built before the 1960's, it is not uncommon for fluorescent lights to contain one of these capacitors. Generally these fluorescent lights will be in the kitchen or bathroom - the worst possible place for them to be if they start leaking or spraying their contents everywhere. In garages, the fluoroscent light fittings are often of commercial origin and will also have a capacitor in them. In Australia, these capacitors were made by the Ducan Condenser Company Pty Ltd and the United Capacitor Company [UCC). The origin of PCBs PCBs (also known as "askarels" - see table elsewhere in this article) are a group of insulating oils that are clear to yellow in colour and have a fruity odour. They are excellent dielectrics [ie, ideal for use in capacitors) and are fire resistant. They have been used in the electrical industry since the early 1930s, for two reasons: • PCBs do not burn or sustain combustion under conditions of internal electrical arcing of transformers. • Power capacitors filled with PCBs are significantly smaller, more reliable, more durable and safer than earlier capacitors filled with mineral oil. It is precisely because PCBs are such stable compounds that they are a problem when they get out into the environment. You've heard of DDT and its problems. Now there is the PCB story. Early warnings In 1966, traces of PCBs were found in the environment. Further research showed that the contamination was due to the highly chlorinated isomers of the PCBs. These components are highly resis- ELECTRONICS WORLD SPECIALS FOR THIS MONTH 240V AC Variable Temperature Soldering Iron. Was $44.95 NOW $35.00 Soldering Iron Stand Was $13.95 NOW $9.95 Solder 250g Roll Was $5.50 Any capacitor of several microfarads and rated at 250V AC or 440V AC, in an aluminium can, is likely to contain polychlorinated biphenyls. Because they are such stable and long-lived compounds, PCBs can pollute the environment for hundreds of years. tant to biodegradation and are toxic. After further tests, in 1973 it was decided to restrict PCBs to uses in electrical transformers and high voltage capacitors. In 1976, Australia banned the import of PCBs and proposed the phasing out of PCB products in use as replacements became available. So why are we still talking about PCBs? Because virtually all the PCBs ever made are still in use and if not reclaimed, will eventually contaminate the environment. Once they are in the soil, PCBs are extremely persistent. They can build up in the food chain and ultimately pose a risk to most living organisms. Early history PCBs were first used in power capacitors and then in power transformers. The first description of PCBs was published by Schmidt and Schultz, in 1881. PCBs were first commercially produced in 1929 as a fire-resistant dielectric for capacitors by the Swann Chemical Company. The company was later bought out by Monsanto Chemical. Dr Frank Clark patented its application for use as a transformer insulating fluid for the General Electric Company in 1931. The first transformers were put into service in 1933. During the 1930s and 1940s, a number of mining accidents had occured because of the poor insulation of cables. These accidents decreased dramatically after the introduction of PCBinsulated cables. The US Underwriter's Laboratory stated: "Transformer askarels are considered non-flammable at ordinary temperatures. Under practical conditions, formation of combustible or explosive mixtures is regarded extremely unlikely. The fire hazard is very small". These unique fire resistant capabilities led to PCBs being used in many other applications such as: AC capacitors, hydraulic fluids, lubricants, paint pigments, sealants, adhesives, printing inks, and even floor waxes. Over a million tonnes of PCB were produced between 1931 and 1977. Virtually all PCBs in ex- NOW $4.50 Universal Tool - Crimper, Stripper, Bolt CutterPliers, ONLY $6.50 Beginners Multimeter 15 Ranges Was $24.95 NOW $19.95 Self-Resetting SA Bi-metal Cutout. Ideal for Battery charger, Power Supply etc. ONLY 75c Business/Home Answering Machine $129.00 Mail Orders Welcome 30 Lacey St, Croydon VIC, 3136. Telephone: (03) 723 3860 (03) 723 3094 Fax: (03) 725 9443 ► .,_ ____________,. OCTOBER 1990 5 TABLE 1: TRADE NAMES OF PCBs Apirolio {Italy) Aroclor {UK, USA) Asbestol {USA) Cloresil Clorextol {USA) Clorinol Clorphen {Germany) Diaclor Diconal DK Duconol (Australia) Dykanal Elemex Educarel Hydrol lnerteen (USA) istence today were produced synthetically. Risks of PCBs There has been considerable evidence gathered as to the effects of PCBs on man and animals. In 1968, several thousand workers in Yusho, Japan, ate food that had been cooked in rice oil contaminated by PCBs. They suffered nausea, lethargy, skin rashes, eye discharges, jaundice and other effects. The maximum dose of PCB thought to have been eaten was about 2 grams. Eventually, some 1200 people were examined, although several thousand were thought to have been affected. The symptoms persisted for several years although there were no deaths directly at- Kanechlor (Japan) No-Flamol (USA) Pyralene {France) Pyrochlor {UK) Saf-T-Kuhl (USA) Solvol (USSR) Therminol tributable to this incident. Several authorities now believe that the real culprit in this Yusho incident was not "normal" PCB at all, but one by-product of the heating of PCBs (320°C): polychlorinated dibenzofurans, which may be 500 times more toxic than PCBs. This by-product, caused by the cooking of the oil, was the poison. Animal tests have indicated that PCBs are associated with liver hepatomas and benign and malignant melanomas in mice and rats. It is now suspected that PCBs are a human carcinogen (ie, they cause cancer). PCBs are also suspected of causing damage to the human reproductive system. This effect is similar to the effect of DDT on the reproductive system. Early tests on PCBs showed that they resembled DDT in · many aspects, the main difference between the two being their onset of toxicity. The toxic effects of DDT appear within hours, whereas the effects of PCBs accumulate over time, and this poses an even greater health risk. The persistence of DDT in the soil is about one year, whereas it is believed that the persistence of PCBs in the soil may be hundreds of years. PCBs can be absorbed through the skin, or simply breathed in as a vapour. They can cause: liver damage; neurological disorders such as headaches, depression and dizziness; damage to the nervous system (eg, weakness, numbness and tingling in the arms and legs}; and "chloracne", a skin condition resembling chronic acne. In 1933, a few years after the beginning of large scale PCB production, 23 out of 24 workers developed chloracne following exposure in a PCB manufacturing plant for about 6 months. Over the years since, many other cases of PCB associated chloracne occurred. Chloracne may occur in nearly every worker exposed to PCBs, if the exposure is high enough. Since the effects of PCBs only become evident through high exposure or high levels of accumulated exposure (bioaccumulation}, we are only now beginning to find out what are the long term effects of lower doses of PCBs on humans. These may not show up until years afterwards. What to do about PCBs Have look around your own home for PCB capacitors. You may be ~urprised at what you find. The capacitor on the left came from a 12-year old dishwasher while the larger one on the right came from a vacuum motor in an old computer tape drive. 6 SILICON CHIP OK, PCBs are nasty compounds. So what do you do if you suspect that one of your fluorescent lights or appliances has an AC capacitor in it which was made before 1978? Having looked at some of the capacitors shown in this article, it is quite easy to identify suspect capacitors. What if they are leaking? If they are leaking, the capacitors should be removed immediately. If they are left there, they may well . fail catastrophically. If the capacitor is associated with an electric motor in an appliance, it must be replaced with a capacitor of equivalent value and rating. In domestic fluorescent lights, power factor correction capacitors can generally be removed and not replaced (if you don't know how to do this, call an electrician). Fluorescent light fittings in commercial or public buildings must have power correction capacitors. In buildings erected before 1980, the fluorescent light fittings are almost certain to contain PCBs. If any of these are found to be leaking, they should all be replaced as a matter of urgency. It is not sufficient to merely replace those that are leaking. Incidentally, unless the fluorescent light fitting is partly dismantled to examine the power factor correction capacitor, it is not possible to know whether it has been leaking or not. That may seem obvious, but the point needs to be made. In the long term, all capacitors containing PCBs should be removed and replaced. If PCB oil does come into contact with your eyes, nose or mouth, flush the area thoroughly with water and seek medical advice, as soon as possible. If PCB oil spills onto your clothing, you should change your clothing and shower thoroughly, as soon as possible. Contaminated clothing should either be disposed of or laundered by people who have been informed of the hazards of PCBs and are familiar with handling procedures. Do not eat, drink or smoke in an area where PCBs have been spilt or are being handled. Cleaning up a spill To avoid contact with the skin, protective clothing should be worn. These should include disposable overalls, protective gloves, eye protection and footwear. These materials should be disposed of with the PCB waste when finished. In Safety measures If you come across a capacitor which is leaking, do not touch it. At the very least, you must wear rubber gloves. If you do come in contact with the liquid, wash your hands thoroughly as soon as possible. Make sure you do not touch your mouth, nose or eyes or severe irritation may result. POISON Made by Ducon Condenser Pty Ltd, this 6.5µ,F 250VAC power factor capacitor is typical of those in millions of fluorescent light fittings in public and commercial buildings around Australia. They all should be removed and replaced with non-PCB capacitors. limited access areas, adequate ventilation should be provided. A respirator with organic cartridges should be used in confined areas. Should any PCB material be consumed, medical advice should be obtained. Disposal Disposing of PCBs is not a simple matter. The PCB material needs to either be destroyed, converted to safe end products, or totally removed from the environment. The following have been put forward as possible solutions for PCB disposal: • high temperature combustion in incinerators, high efficiency boilers and cement kilns; • radiant energy; • chemical dechlorination; • biological degradation; and • landfill or subterranean deposition. None of these disposal methods are available in Australia at present. Great. Nor are there any real plans or policies for disposal of large numbers of capacitors conOCTOBER 1990 7 ® POISON What you need to know about polychlorinated biphenyls ... Homes more than 30 years old often have fluorescent light fittings with dodgy capacitors. The older they are, the more likely they are to leak. This fitting was one of several in the ceiling of a 40-year old house. Exercise due caution when removing PCB capacitors from light fittings. taining PCBs in Australia. Great again. Currently, high temperature incineration is the most cost effective way of totally destroying PCBs. Two companies in Australia have contracts to ship our toxic wa.stes to Europe for incineration. Capacitors may be stored in sealed 205 litre drums and sent to these two companies for storage and eventual despatch overseas for incineration. The two companies in question are: • AACI, 10 Bridge St, Granville, NSW 2142. Phone 02 682 1660; and • Jancassco Pty Ltd, Ordish Rd & Cahill St, Dandenong, Vic 3175. Phone 03 794 9633 . OK, so what do you do when you have one or a few capacitors containing PCBs. Legally, you may dispose of these with your household garbage. Eventually, that means that lots and lots of PCB filled capacitors are going to end up in municipal garbage tips around Australia. Or worse, they may be burnt in municipal incinerators. We are not happy about this. Nor should you be. 8 SILICON CHIP In our opinion, you should contact your local council and ask them where these capacitors are to be collected and stored. If your council does not know (or worse, tells you to stick it in the garbage), they should contact the NSW State Pollution Control Commission, the NSW Metropolitan Waste Disposal Authority (or the equivalent bodies in your state), or the Electricity Supply Association of Australia. By rights, all capacitors containing PCBs should be safely stored for ultimate disposal by high temperature incineration. If you are involved with large scale replacement of capacitors High temperature incineration is the most cost effective way of destroying PCBs containing PCBs in commercial or public buildings, you should contact the above bodies before proceeding. Bibilography (1). The Properties of Askerels & Recommendations For Their Use in Electrical Equipment - Electricity Supply Association of Australia. D(b)32-1984. (2). Assessment of Polychlorinated Biphenyl (PCB) Wastes, by Anthony J Farrugia. 88/1. ISBN O 7305 0774 2. State Pollution Control Commission. (3). Report of An Inquiry Into the Potential Health Hazards of Polychlorinated Biphenyl Compounds in New South Wales Schools Department of Education, (24/11/ 89). (4). Encyclopaedia of Occupational Health & Safety (Third Edition) International Labour Office, Geneva. (5). Spot the PCB - NEWSWIT (December, 1989), University of Technology, Sydney. Acknowledgement Special thanks to Bill Holliday (University of Technology, Sydney) and to Leo Pomery (NSW Teachers Federation) for their assistance in the preparation of this article. ~ 144- 148MHz For The 6m Band/ Amateur Band Converter Simple FM Receiver This converter will allow you to receive the 2m amateur band on your 50-54MHz receiver (K-6005) . The modular design of this circuit allows it to fit comfortably inside the K-6005 receiver, so changing bands will be as easy as flicking the switch. You can now easily listen to amateur radio on the 50 to 54MHz band with this quality, yet very simple unit! In fact, most of the receiver functions on this unit, are performed by a single IC (the new MC3363 from Motorola)! This project will also form a basic 'turntable IF' receiver module for future converters, to cover other amateur bands! Full form kit with double-sided PCB, transformer, case and all necessary components. , ~J.. Cat K-6006 420-450MHz ~Jf.f ,-, iio ,o?. O 0 s4995 I QQ 1 ,{fl ~ .~ 0 Amateur Band Converter~~~ Another converter to give your receiver even greater versatility. By building this simple circuit into your K-6005 receiver along with the K-6006 2m converter, the 70cm band , which includes the popular 432MHz ~NEW' frequency will be yours to enjoy. ·~ Cat K-6005. s139 QQQ~ s39ss Q Cat K-6008 Electronic Dice UHF Transmitter Key This handy kit is more than just a random number generator. It displays its numbers in the traditional die format on two rows of three LEDs. You can even see the Electronic Dice counting as numbers roll by and stop just past that elusive six. Short form kit with all components, PCB, IC sockets, and battery holder. This new design uses a SAW fi lter for improved frequency stability and eliminates the need for transmitter alignment. It features a flashing LED to indicate the button is being pressed and an automatic cut-out after 10 seconds if the button is accidently held down. Kit comes complete with all components, transmitter case and battery. 12 $ Cat K-3532 95 Q $2995 Cat K-3259 Q Logic Probe This invaluable kit comes with a special purpose case, hardware and test leads. LED indicators on the probe will identify lo9ic HI, LO or PULSE states in both TTL and CMOS logic circu i~ ~ $ Cat K-7405 Portable AM Stereo Radio Digital Sine/Square Wave Generator This new Digital Sine & Square Wave Generator uses high speed CMOS ICs and a digital filter to produce waveforms over a frequency range of 0.1 Hz to 500kHz. It also features a 4- digit frequency readout, an output level control, and course/fine frequency adjustment. Cat K-7350 QQQ[2] 2495 Q '149 Small, lightweight, su perb stereo sound and incredibly easy to tune! The Wide Band AM Stereo Radio is quite simple to build and requires no fancy tools or equipment! Comes complete with case, stereo economy headphones, pre-punched front panel and all components. All YOU have to do is put it together, add two AA batteries and you're away! Cat K-5200. QQ s79ss Kits marked with this symbol involve mains power wiring. Take extreme care when working with this equipment. Degree Of Simplicity Q QQ QQQ Simple Intermediate Detailed OCTOBER 1990 9 i~FU:ingl - , With Bargraph Display And Trus HMS! 3999 Count DMM At last, true RMS measurements in the palm of your hand! Most test equipment does not directly measure RMS values. This one however, measures the value of the sine wave giving accurate readings. Features include auto ranging, data hold, . frequency measurement, continuity, and diode test. 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Cat Q-1470 119 Outstanding Va/us/ Full Function Digital Multimeter Amazing value! You'll discover features you'd only ex~ect in a meter costing much_ more!_With a full range of functions, including diode test, capacitance and transistor test plus inbuilt frequency to 20MHz, and low power consumption allowing up to 200 hours of use. $ 9 14 10 SILICON CJ--IJP 18 Range Digital Multimeter This pocket sized multimeter proves that performance can be a lot bigger than price! It takes three measurements per second to give you super-fast response over its 18 ranges and features the latest in IC technology to provid~ you _with _a highly reliable meter in a tiny, light weight package. Cat Q-1442 33 Range Digital Multimeter 33 ranges in a pocket sized mu!timeter! This amazing little device can do almost everything you've wished a multimeter could do. It uses the very latest in IC technology to deliver these features in such a compact, reliable, and accurate meter. Some of those great extra features include frequency measurement, logic testinQ, continuity beeper, and. transistor testing. Cat Q-1 446 s79e5 PANEL METERS UNIVERSAL RANGE These 100uA universal panel ~ meters can be easily adapted for SMALL MU-45 TYPEany scale of Volts, Amps, or Ohms. By combining them with Scale size: 55x30mm Overall our SHUNT PACK and METER size: 58x52mm Cat Q-2045 LABELS they will be capable of s-;;;;;;iiiiiri:i==::=::;;;;;;;i operating over the range 100uA ,~ to 10A and 1V to 100V. • "" ' ' --;,.,• LARGE MU-65 TYPEScale si7~: 96x49mm Overall size: 101 c82mm Cat Q-2065 s1&ss s21ss SHUNT PACK- Shunt resistors from 1.1 to 1,000,000 ohms plus resistance wire and instructions. Cat Q-2046 ~ UNIVERSAL TEST LEAD SET s1ss =- - ~ I --- •=t Professional quality test leads for virtually any application in one screw-together system. Suitable for most meters and test gear. Comes with ..... Coiled Leads fitted with insulated handles, 4 x 18mm (long) 1.5mm probes, Spade lugs, Alligator clips, Banana plugs, Right-angle adaptors. And they're all housed in a handy plastic wallet. Cat Q-1935 r . . - ~- . - s2sss t' Design Your Own Circuits FAST AND EASY/ WISHMAKER II PROTOTYPE DESIGN STATION With the Wishmaker II you can quickly and effortlessly build prototypes of your digital designs without the need for soldering, then test them with the vast array of test and measurement equipment built into this impressive unit. A rug9ed and portable design make the Wishmaker II a must for engineers, technicians, students, and hobbyists who need a device that can get their designs up and running fast! The Unit comes with a removable solderless breadboard, wire jumper kit with 350 assorted lengths, probes, and detailed manual. cat 0-1435 s499 Item limited to larger stores MAJOR DICK SMITH ELECTRONICS AUTHORISED STOCKISTS: N.8.W.: AIIMIDALE: New England Electronics 711655 BALLINA: Ballina Electronics 867022 BOWAAL: F.R.H. Electrical 611861 BROKEN HILL: Hobbies & Bectronics 884098 COOTAMUNDAA: Cootamundra Music& Ute 422561 COFFSHARBOUR: Coffs Harllour Electronics 525684 DENILIQUIN: Deni Electronics 813672 DUBBO: Chris's Hi Fi 828711 FORSTER: Fors1er Village Electronics 545006 GLEN INNES: John Sommertad Electronics 323661 GRAFTON: Repairs and Soares 421911 GRIFFITH: Miatronics 624534 INVERELL: lnverell Electronics 221821 LEETON: Leeton Audiotronic 532800 LIGHTNING =E:c~~:,.&E1~:ni~fos\1ti1l!,tE:'fi.~~~~~~h~<;R~t¾3,l-~~~i~;S:,!;~';~~~2~'N1~JJilV Nelson Bay Elect & Hobbies 813685 NOWAA: Nowra Electronics 210722 ORANGE: Central West E~ctronics 626491 PARKES: S1rad Music Centre 623366 PORT MACQUARIE: Hastings Comtu1er Service 834574 TAIIEE: Brads Electronics 526603 11 1 1 I ruroi~~~:r~fJ;~t~'g''~?~ MOOWELL: Morwell Electronics 346133 SHEPPARTON: Andrew Guyan Electronics 219497 SWAN HILL: Nvah Dis1nct TV Service 329303 WARRAGUL: Roytaine 234255 WARRNAMBOOL: Koroit S1 Elec Services 627417 QLD: AVA: Delta Electrix 831566 BUNDABERG: Bob Elkin Electronics 721785 CALOUNDAA: Electro-mart 918533 DYSART: Dysart Videotronixs 582107 INGHAM: Masons Electronics 763188 MACKAY: S1evens Electronics 511723 MARYBOROUGH: Keller Electronics ~~:~1:~~~m mi ~m~ ~:r~~i~ dif~9u~1tot:~,~~ ~c:n~~\W~ COLOURED PLASTIC KNOBS Now your projects can really look smart with these contemporary styled knobs. Use them to colourcode controls and even swap the inserts for greater variety. Cat P-7050 Rad Cat P-7052 Orange ONLY EACH Cat P-7054 Blue Cat P-7056 Green $195 RESISTOR SUBSTITUTION WHEEL Select values from 5 ohms to 1M ohm in 36 steps using the most common divisions. Comes complete with leads $ and crocodile clips. Cat Q-1410 1995 . 'J PROTECTIVE POUCHES LARGE ZIPPEliED Suits many of the $995 larger meters in our range. Cat Q-1514 SMALL SOFT POUCH With Velcro zip. sft95 Suits our smaller meters. Cat Q-1513 ~;, HOLSTER WITH BELT Lightly flexible yet hardy cradle which suits our 0-1516 DMM. Impact absorbing and can be worn on belt or s495 used on the bench, etc. Cat Q-1522 !ll"" $ t~=~o/.~r:::~~~~~J ~l~f~i1~~ •~~=:~ ~~:uJta~~~U:.:; ~~~i~~~ 11 2 LINC~: Basshams TV & Comp Wortd 822788 WHYALLA: Et• Electronics 454764 WA: ALBANY: Micro Electronics 1 I ~21/;;?ni~=J.:Jo~l~"%%:~t1~:~i~sGJ8'\A~%n :iui~t\~n\;).. ~~~ Ef.!:l~i£rAATHA: Daves B1017/BL OCT0BER1990 11 SPOIL ':JOURSELF! Or Give Dad l a Handy Tool The One Tool That Does It All! 3-IN-1 Modular Tool • • • • It's a drill plus drill bits;-~91":::~ It's a Soldering Iron plus solder It's a Screwdriver plus drivers And it's rechargeable too! ~ Unbeatable ~ 95 value at s79 Cat T-5712 Varitemp Iron The one soldering iron that suits a range of applications. 240 volt operation with 25 watt capacity, makes it the ideal choice for an allround iron. The temperature control is conveniently placed on the handle, and a great range of tips is available to suit most applications. Cat T-1350 Heat 'N Strip Gun A great tool to have around the house. Ideal for heatshrink work, removing old paint, drying ... you'll find hundreds of uses for the Arlec Heat 'N Strip gun . It's mains operated and light and easy to use. $6295 Cat T-4845 Perfect For PCB Work! Arlec Supertool RRLEC The Arlec Supertool takes the hassle out of working on PCB's. It sands, it polishes, it drills, it engraves, it mills. Comes complete with wire brush, milling cutters, grinding wheel, high speed drills, chuck collets, eraser sticks and plug pack adaptor-all in a handy carry case. Cat T-4754 Just s79 95 s29e5 Easy Etch Engraver • - - - - - - - - - - - - - - - - - - -- - With the Arlec Easy Etch Engraver you can Fits In The Pocket! easily and quickly mark your tools, stereo equipment and household goods with a · permanent identification . Steel bits let The totally portable, butane powered soldering iron that will fit easily you engrave on metal, plastic, or wov,O::.::d;:::.-:_---:=;;;:;:;;.!,,_ into your shirt pocket. It provides up to 60 minutes continuous use , h di d - .rtt/t 1t s easy to an e an at full power (equivalent of 60 watts) and has temperature control comes complete with v/ ...., ·u V INGRAVSR af"-LE from 10 to 60 watts. ~ a 1 2v plug pack ~ Cat T-1370 and long cord. Butane Solderl·ng Iron ~= -:. 4 s3995 Selected Portasol Replacement Tips T T T T T T 12 This month just s9 95 1368 Hot Knife suits 1376 Hot Knife suits 1377 Blow Torch suits 1382 Hot Blow suits 1379 3.2mm suits 1381 4.8mm suits SILICON CHIP s399s Cat T-4753 ,.,...,,'!!A~,., Gas Powered! RED HOT SPECIALS! Normally s15 95 iini::: Jfl .~ T 1370 T 1374 T 1374 T 1374 T 1374 T 1374 The Professional l'fR ":'! E~~~N~• 'P'1cket' Soldering System Ideal for the hobbyist, handyman or technician this butane powered kit allows you to make repairs anywhere, anytime. A must for urgent field work, etc! It's a complete soldering system with the equivalent of 10-60 watts of power and temperature adjustment up to 400 degrees Celsius. Your Portasol kit will include 4 tips, a cleanin g sponge, and heavy duty case with clip-on iron stand . Cat T-1374 c.a+ (ii$Jj ►c . .iii.....-. po,tasnt Li 8 1017/MS we,,e OVERSTOCKED so theseitemsmustgo! TOOL UP WITH THESE SAVINGS! "F' CLAMP SET With Flexib/BShatt/ MAGNETIC PICK-UP TOOL Now it's easy to retrieve those little bits that go clank in night and end up at the bottom, underneath or caught up in your work. With insulated handle and 5 x 285mm flexible shaft: Cat T-4530 SCREWDRIVER BIT SETS PUSH-ACTION MAGNETIC 5 BIT SET T-BAR MAGNETIC Cat T-4512 Cat T-4505 Cat T-4500 Cat T-4515 $6.95 $6.95 $4.95 $4.95 Just SAVE $3 SAVE $3 SAVE $1 SAVE $1 $295 savasn ~ Fully Insulated! HO[DING SCREWDRIVER SET SPECIAL! • A high quality 5-piece screwdriver set that's fully insulated to help eliminate the 'Zap! ' if you harpen to touch the wrong thing. What s more, it 'holds' the screws so you don't drop them into awkward places. Comes with - 3 flat blades : 5 x 150, 4 x 125 & 3 x 125mm. 2 x Phillips head: No's 1 & 2. Cat T-4395 A complete soldering aid set at a bargain price! You get a fine-point and slotted end probe, scraper end ~ and wire brush probe, angle scriber ~ • · and scraper probe, an aluminium ill''l31I ~ heatsink and 170mm tweezers. An essential kit for YOUR tool box! Cat T-2606 ----- c,.{\j F .g:~ ~ ,..,. - · f:~ ~~-~ SOLDERING AID SET C::0• -----s s118ve• :__.:..-• $695 Wl= ~ ·~ 9 tools or knives. Cat T-55; Nows1995~ i\ · ECONOMY PENCIL BLOWTORCH Great for heatsink work, silver solder, gold, silver, brazing, glass work, etc. It fits easily in your pocket and is powered by butane gas (the same as they use in cigarette lighters, etc). Cat T-1380 VAiiief '1595 .:.:..:-- - - - -- -- - 995 ~GREAT VALUE! ~ --------- INSPECTION MIRROR & PICK-UP TOOL Great for wnen you 're working in tight places. This tool will allow you to get in there and see what's happening. The other end of the telescopic arm doubles as a • magnetic pick up tool. Cat T-4525 s595 "G' CLAMP SET Three handy 'G' clamps that are perfect for most hobby work, model making, etc. All fit the 30mm (diam.) magnetic base supplied. Sizes include 40mm x 35mm, 30mm x 30mm & 20mm x 25mm~ Cat T-4755 J,...J/ <Sil~ UTILITY KNIFE WITH 2m TAPE MEASURE This 50cm strip simply screws to the wall and holds any shaped metal :nnal/y ,;;5~ ~~ s595~ MAGNETIC 1 TOOL HOLDER · fill 1 Just like a spare set of hands for the workbench or toolbox. Three sizes: 20 x 120mm, 20 x 80mm & 20 x 40mm . All three clamps fit to the 38mm magnetic base included in pack. Cat T-4750 This handy tool is really three tools in one-- a retractable blade knife, a handy saw, and a 2m tape measure. '!L?~~;e s495 RBdU~ sav~ Cat T-3610 $595 OCT0BER 1990 13 What ever the size af your project, we have a case ta fit! Horwood 1NsTRuMENT cAsEs ALUMINIUM BOXES Superbly finished, beautifully constructed and designed Horwood instrument cases are a favourite amongst hobbyists and project builders alike. They look good and come with chrome (84 Series) or aluminium (93 Series) front panel handles. Just the thing for those weekend projects that get left lying around! • Put them in an economical aluminium box. These boxes come in two pieces which slide together and are complete with screv:s. 84 Series ---(Depth 200mm, 110x51x70mm Cat H-2300 $6.95 Height 100mm) 104x60x46mm Cat H-2305 5 95 $ . Width Cat No. Price 127x 102x76m m Cat H-2320 $ 7.95 150mm H-2453 $29.95 133x76x54mm Cat H-2325 $ 5.95 200mm H-2454 $31.95 152x132x103mm Cat H-2330 $ 9 .95 250mm H-2455 $34.95 180x158x118mm Cat H-2335 ,......s.1~2•.9.5.. 305mm H-2456 $39.95 H-2457 $42.00 425mm K & W INSTRUMENT 93 Series CASES (Depth 230mm, These cases are solidly constructed Height 75mm) with a hammer tone steel cover, Width Cat No. Price aluminium base, and recessed front panel. 150mm H-2462 $25.95 200mm H-2463 $27.95 150x52x95mm Cat H-2802 $12.95 250mm H-2464 $29.95 100x77x125mm Cat H-2804 $13.95 305mm H-2465 $32.95 200x65x 125m m Cat H-2806 $15. 95 l1!4•2111!15mlllll!lm~~!l!llll!llll!•Hlll!l-!11!11241111!6~6--11!1111•$•3•4•.9•5 255x77x150mm Cat H-2808 $18 95 255x150x 15 omm Cat H- 2810 $ 25 :95 Exclusive To Dick Smith Electronics! 305x90x195mm Cat H-2812 $25.95 EXTRUDED ALUMINIUM CASES 305x200x165mm Cat H-2814 $29.95 76 X 102mm Length Cat No. Price 10 Up. 76mm H-2420 $22.95 $21.80 ECONOMY METAL CABINETS 102mm H-2425 $25.95 $24.'65 153mm H-2430 $29.95 ,..,$28.45 Beautifully made cabinets to suit a huge ----••lllllllillllllllillllllllllliiil...______. variety of projects. They consist of an aluminium base, metal sides with cooling slots, and self tapping screws complete with cup washers. They come in an attractive two-tone finish. 102x56x83mm 150x6"i,.. :o3mm 150x76x134mm 185x70x160mm 14 SILICON CHIP Cat Cat Cat Cat H-2741 H-2742 H-2743 H-2744 A superb range of cases based on a specially made 18 gauge aluminium extrusion giving cases which are ultra strong and ultra reliable. $6.95 $8.95 $9.95 $11.95 You'll never have to solder and re-solder experimental circuits again when you have a Wish-Board breadboard kit. These boards are made of a durable ABS plastic and have colour-coded markings to indicate power distribution rails. Phospher bronze and Nickel silver are used to achieve high endurance contacts for insertion holes and an anodised aluminium base plate ensures excellent high frequency performance. Your ingenuity is not limited by the size of your breadboard either-- every board has dovetail joiners along it's edges to enable it to interlock with others. A box of assorted hook-up wire, terminal posts, and rubber pads is supplied with each of these kits so you'll need nothing more than your own inspiration and components to get under way. H-4020 H-4022 H-4042 sgg s39ss H-4035 sag H-4045 s1095 i! I i H-4030 s995 895 DS XPRESS PHONE & MAILORDER SERVICE PHONES SECURITY AUDIO COMPUTERS Outside Sydney (FREE Call) 008 22 6610 Sydney And Enquiries - 888 2105 FAX: (02) 805 1986 or write to DS XPRESS, PO BOX 321 N/RYDE NSW 2113 All Major Credit Cards Accepted. O/Nite Courier Available. 24 HOUR DESPATCH OF ALL ORDERS NSW • Albury 21 8399 • Bankstown Square 707 4888 • Blacktown 671 7722 • Brookvale 905 0441 • Bondi 387 1444 • Campbelltown 27 2199 • Chatswood Chase 411 1955 • Chullora 642 8922 • Gore Hill 439 5311 • Gosford 25 0235 • Hornsby 477 6633 • Hurstville 580 13622 • Kotara 56 2092 • Liverpool 600 9888 • Maitland 33 7866 • Miranda 525 2722 • Newcastle 611896 • North Ryde 878 3855 • Parramatta 689 2188 • Penrith 32 3400• Railway Square 211 3777 • Sydney City 267 9111 • Tamworth 661711 • Wollongong 28 3800 • ACT• Belconnen (06) 253 1785 • Fyshwick 80 4944 •VIC• Ballarat 31 5433 • Bendigo 43 0388 • Box Hill 890 0699 • Coburg 383 4455 • Dandenong 794 9377 • East Brighton 592 2366 • Essendon 379 7 444 • Footscray 689 2055 • Frankston 783 9144 • Geelong 232711 • Melbourne City 399 Elizabeth St326 6088and 246 Bourke St639 0396 • Richmond 4281614 • Ringwood 879 5338 • Springvale 547 0522 • QLD • Brisbane City 229 9377 • Buranda 391 6233• Cairns 311 515 • Chermside 359 6255 • Red bank 288 5599 • Rockhampton 27 9644 • Southport 32 9033 • Toowoomba 38 4300 • Townsville 72 5722 • Underwood 341 0844 •SA• Adelaide City 223 4122 • Beverley 3471900 • Elizabeth 255 6099 • Enfield 260 6088 • St. Mary'B 277 8977 •WA• Cannington 451 8666 • Fremantle 335 9733 • Perth City 481 3261 • Midland 250 1460 • Northbrid e 328 6944 • TAS • Hobart 31 0800 •NT• Stuart Park 81 1977 - --- The Largest Australian Electronics Retailer! 63 Stores Across Australia OCT0BER1990 15 VINTAGE RADIO By JOHN HILL The d.iff erent types of radio valves This month, we shall be looking at valves a little more closely. Instead of discussing them collectively, it's now time to discuss them individually and to sort them into categories depending on their applications. In the early days of valve radio, everything was wonderfully simple. The 3-element or triode valve reigned supreme and was the only type in use. What's more, the receivers were all battery operated and had from one to five valves (sometimes more), depending on price. Those old triode valves weren't all the same. Most were made to suit special applications such as radio frequency amplifiers, detectors, audio amr>lifiers and audio output. Each manufacturer produced their own range of products which tended to complicate things a little, but the decision as to what should be used for a particular job was fairly straightforward in the mid 1920s. Early radios had a few problems, one such problem being the high cost of batteries. The purchase of dry cell "B" batteries at six to 12-month intervals was a considerable expense, to say the least. There was, therefore, a large market just waiting for mains operated radio receivers and this type of set became increasingly popular from around 1927 onwards. These first "all electric" radios had two types of valves: the usual complement of triodes, plus a double diode or 2-element valve which was used to rectify the AC mains current to DC. The late 1920s to mid-1930s saw a period of intense development for both radio valves and the receivers they were used in. Mains-operated superhet receivers were taking over from the old squealing reaction sets and radio improved so much in such a short time that the period can only be described as "remarkable"! Within this rapid developmental period, numerous new types of valves evolved and most were tailored to suit the AC-powered superhet receiver. These new types included tetrodes, pentodes, pentagrid converters and variable mu valves that worked in conjunction with diodes for automatic gain control. Beam power tetrodes and pentodes were also developed for power output applications. The 5-valve receiver In the mid 1920s, battery operated triode valves were the only radio valves in common use. Things really w ere simple in those days ! 16 SILICON CHIP It wasn't long before a standard pattern emerged that was to be adopted by all manufacturers for many years to come. While commercially made radios ranged from cheap 3-valve sets to monsters with a dozen or so valves, the industry standard was the 5-valve receiver. The rectifier valve was usually included in the count even though it did nothing more than convert AC current to DC current for the high tension supply. In other words, a 5-valve receiver was really a 4-valve receiver and the majority of The valve complement of this old Radiolette was common for many 1936 receivers. The line-up was 80, 6A7, 6D6, 6B7 and 42. This photo shows some early AC valves. They are (from left) 224, 227 and E406. Note the top cap on the 224 (left). These three valves - 2A5, 42 and 6F6 - have the same electrical characteristics, the only differences being heater voltages and base pin configurations. sets made at the time fitted into this four plus one or 5-valve category. Popular valve types Let's take a close look at the valve complements of some of those old receivers and, by so doing, establish popular valve types. This information will be a good start to compiling a list of common valves; the types that radio restorers should have on hand. Domestic superhet radio receivers used only a few types of valves. These can be categorised as: power rectifiers, frequency changers, radio frequency amplifiers, detectors, audio amplifiers and audio output valves. The detector stage consisted of a diode (much smaller than the ones used in power rectifiers) and this was normally [but not always) incorporated into one of the other valves. Some old sets used a 6H6, a double diode which performed the roles of detection and automatic gain control. I have in my collection of radios several 1936-37 mantle models. The valve complement used in these sets is as follows: 80, 6A7, 6D6, 6B7 and 42. In order, these valves perform the following functions: • 80: supplies high voltage DC to the other valves; • 6A7: mixes incoming RF signals with the oscillator frequency to form an intermediate frequency; • 6D6: amplifies the intermediate frequency; • 6B7: amplifies the audio signal from the detector (the detector diode is within the same envelope); • 42: additional audio amplification prior to loudspeaker. Any radio that is about two or three years older than the previous example would most likely have 2.5-volt valves instead of the 6.3-volt types just listed. One could expect to see the following valves in such a receiver: 80, 2A7, 58, 2B7 and 2A5. In this case, all these valves are electrically the same as the first example except that they have 2.5V heaters instead of 6.3V heaters, with the 5V 80 being the only exception. However, there could be other variations for there are many types of 2.5V valves. The output valve need not be a 2A5; it could well be a 47 or a 59, so what you expect to see and what might be there are often two different things. Going back once more to the first example, the valves in these particular radios were becoming obsolete while the sets were built. The "new" octal-based valves were coming into use at the time and if OCT0BER1990 17 separate heater transformer or by using different valve sockets. European valves A valve equivalents manual is a handy book for the vintage radio enthusiast. If you cannot locate the original valve type, it can nominate a suitable substitute. these radios had used octal valves, then the valve complement could have been: 5Y3, 6A8, 6U7, 6B8 and '6F6. Once again, the valves are electrically the same as those in the first example but the octal valves have different bases. Therefore, in the 1930s, a good many apparently different valves were basically the same, the only real differences being their bases and heater voltages. Hence, one set of valves can be interchanged with another by the addition of a Unfortunately, the picture is not quite as clear as it may appear to be at this stage . . The valve types mentioned so far have been American types; the European varieties complicate matters somewhat. European manufacturers made a range of valves that were not generally interchangeable with American types. For a start, the bases were different. British 4 and 5-pin types used a different arrangement to American 4 and 5-pin types and so on. There was also a series of 4V valves and from 1936 many Philips and Mullard valves used the side contact "P" base, making substitution totally impossible. In addition, English Mazda valves had their own non-standard version of the octal base just to make things even more difficult. There were many differences and variations between American and European Vintage Radio Service Tips (From Resurrection Radio). This is the start of a regular series briefly detailing the day-today experiences of a vintage radio service technician. Some problems are unique to specific brands and models but many are commonplace faults found in many radios. Silver Mica Capacitors • Alignment drift - sometimes the IF gain can drop with a click when final alignment is being performed . This is often caused by a faulty silver mica capacitor across one of the IF windings. Try to repeak each slug until one has a noticeable improvement in gain. Note the slug, disassemble the IF transformer and replace the capacitor across the corresponding winding. • IF slug won't peak - open circuit silver mica capacitor across the appropriate winding. • HMV Little Nipper - crackles and popping noises in late · model Little Nippers can be caused by a defective silver mica bypass capacitor on the plate of the 6AV6 audio valve (see Fig.1 ). 18 SILICON CHIP 100pf SM I..,. .02 50k 1M 270k .,. HT+ points tor the new capacitors. They may eventually short and take out the rectifier and power transformer. • 50Hz hum in early sets is often due to long unshielded leads in the audio section. Replace these with shielded cables where necessary. • Can't track down an elusive hum? - when all else fails, try connecting a large electrolytic (25-1 00uF) across the back bias resistor (be sure to observe the correct polarity). Fig.1 Hum Problems • For those that don't already know, most hum in vintag e receivers can be traced to old dried-out electrolytic capacitors, both tubular and chassis mounted . Replacement usually cures the problem. If you leave the chassis mounted capacitors in the set (and most people do). check that they are not leaking . Also, don't leave them in circuit as convenient tie Audio Distortion • Audio distortion is the most common symptom in vintage radios that are still operating but have not been serviced for many years. It's generally the result of a positive voltage on the control grid of the output valve. A leaky coupling capacitor from the plate of the audio amplifier is the likely culprit and this should be replaced. An output valve with low emission can also exhibit similar symptoms. Resu:r:reetion Radio The original vir.itage wireless specialists Our skilled technicians offer QUALITY repairs & restoration. We have a large stock of bakelite and timber radios fully restored and for sale. Valves, high voltage capacitors and other specialised parts available. ADDITIONAL SERVICES European side contact or P-base valves were produced by some manufacturers from the mid-1930s. P-base valves are most commonly encountered in sets made by Philips and Mullard. 58,78,235,6D6, 6U7 ,6G8,EBF35,6AR7, 6BA6,6BH5,6N8 MIXER IF AMPLIFIER 6H6,EB4 * 55, 75,85,227, 2A6,2B7,2B6,2B8, 6SQ7,6BD7,6AV6 41,42,45,47, 59,2A3,2A5,6AG6, 6F6,6V6,EL3,EL33, 6AQ5,6M5,6BV7,6BQ5 DETECTOR AF AMPLIAER OUTPUT COPIES OF: CIRCUIT DIAGRAMS $5.00 SERVICE MANUALS $10.00 AVAILABLE FOR MOST MAJOR AUSl . MAKES FROM 1934 ONWARD. WANTED - valves, radios, etc., purchased for cash . Call in to our showroom at: 51 Chapel Street, Windsor, Vic 3181 PO Box 1116 \ 57 ,AK1,AK2,6AN7,6BE6, ,_____.~.._, ECH33,ECH35,EK2,EK32, 6J8,6K8,6SA7 LOCAL OSCILLATOR 80,5Y3,5V4,6X4, 6X5,6V4,EZ3 EZBO HIGH TENSION D C ~ W E R ;UPPL y 240VAC LOW TENSION AC (VALVE HEATERS) *mooE DETECTION: DIODES USUALLY CONTAINED IN OTHER VALVES Fig.1: this diagram lists most of the valves likely to be encountered in the average Australian-built receiver and shows where they are used. About 60 different types just about covers everything. valves and while some may be interchanged, most can not. Fortunately, the majority of Australian manufacturers went with the American system and most of our locally made sets have American type valves in them. However, P-base valves do appear in some radios, particularly those made by Philips and Mullard. Personally, I make a point of avoiding radios with P-based valves. Unless exceptionally appealing, I prefer to collect receivers that have what I consider to be "standard valve types". Now I know that last statement will stand on a few toes but as I see it, P-based valves are non-standard varieties and I avoid them where possible. Although I have a few sets with the odd P-based valve in them, I prefer the standard American type valves because of their better availability. The advent of the miniature baseless valves saw the end of an era where so many manufacturers and countries had their own special standard. Miniature valves valves have either seven or nine pins and no topcap connection to come loose and fall off. It was not until this last generation of valves that some form of international standardisation came about. Frequency converters Frequency converters warrant some discussion as they come in many shapes and forms. There are pentagrid converters, octodes, triode heptodes and triode hexodes - whether they be in one envelope Telephone: (03) 529 5639 CHRISTIAN BLIND MISSI(~, ·J Re$tot"iK9' {:~~,, M1K COUPON Please cut and send to: CHRISTIAN BLIND MISSION INTERNATIONAL, P.O. Box 5, 1245 Burke Road, KEW, Vic. 3101 Phone: (03)817-4566 D G Please send me further information about CBMl's work. As long as it is possible for me, I will help: monthly D quarterly D annually D to prevent blindness D to restore eyesight D to rehabilitate the blind Enclosed is my gift of$ _ _ _ _ _ _ D Mr/ Mrs/ Miss, _ __ Street, _ _ _ _ __ _ _ _ City,- ~ - -- ~- .. _.. Postcode, OCT0BER1990 19 Problems? ... and you don't have our NEW 1990/91 148 pf1ge electronic parts and accessories catalogue ... Its our latest TRADE catalogue for the consumer ARISTA ... Your one-stop problem solver. ... Stylus ... ... Plugs, Jacks and Sockets ... ... Batteries .. . ... Cable ... ... Tools and Technical Aids .. . ... Plug and Power Packs .. . ... Car/Auto Accessories ... ...Boxed Hi Fi Speakers .. . ... Raw Replacement Speakers ... ... Speaker Accessories ... ... Telephones and Intercom .. . ... Public Address Accessories .. . ... Security and Alarm Accessories .. . ... TV/Video/Antenna Accesories ... ...Videocam Accessories ... . .. Audio Accessories ... ... Headphones ... ... Computer Accessories ... , ...Microphone Accessories .. . .. .Mixers, Amplifiers, Equalizers ... Just about anything you want ... Get your catalogue complete with "Recommended Retail Prices" free from your local ARISTA dealer or send $2.50 P & H and your return address to: ARIS'I~ ELECTRONICS PTY LTD PO BOX 191. LIDCOMBE, NSW, 2141 20 SILICON CHIP American and European valve bases were of different designs which prevented convenient substitution. At left is the European 4-pin style while at right is the American 4-pin base. or two. There are a number of ways to produce an intermediate frequency but this particular story is not going into those details at this point. The mixer and the oscillator stages of a superhet receiver can be designed to work with one valve, two valves or two valves in the one envelope. In the block diagram (Fig.1 ), all the frequency converter valves, regardless of what type or where or how they are used, are listed under "mixer" . Fig.1 lists most of the valves the vintage radio enthusiast is likely to encounter in the average Australian built receiver. About 60 different valve types just about covers everything. Note that the last statement says "just about covers everything". There is always some obscure set that has something different in it. Also note that the list covers from the early 1930s on. Mains operated radios from around the 1928-1930 era used entirely different valves but these have been deliberately left out because of the rarity of such sets and suitable replacement valves. Astor Mickey I recently picked up an Astor Mickey of mid-1950s vintage only to find that it had a 6AD8 in it, a valve that was not in my collection. However, a study of the valve manual showed that the 6AD8 is a very close relative of the 6N8. Slipping a 6N8 into the socket had no effect on the set's operation which goes to show that a ring-in valve will often do the job just as well. Astor seems to be the odd one out. I also have some early 1930s Astors which use 41 and 43 output valves instead of the normal 42 . The 43 seems most odd for it has a 25V heater, while the remaining valves in the set are of the usual 6.3V variety. No, it's not an AC/DC set and the heaters are not connected in series . Many valves can be recognised simply by looking at them. Rectifiers are easily identified by their internal construction. Anyone familiar with valves can instantly pick an 80 from a 5Y3 because of the different bases. Likewise with a 6X4 and a 6V4. The 6X5 is different again. Valves such as the 6B6, 6SQ7, 55, 75 and 85 all look the same inside. However, the size and shape of the glass envelope, the type of base and the heater voltage will soon sort most of them out. Anyone familiar with these valves will be able to distinguish between them. Getting to know all these old valves takes considerable time and effort but it is very necessary if one takes vintage radio seriously. ~ · For Features and Performance ... For 12 Volt or 24 Volt systems LowCost Battery Discharge protection Fully Protected Low Noise Prices include TWO x1/x10 switch probes MODEL: BCE1 & BCE2 lllllllll SETEC The high powered performer Sctec Pty. Ltd. 6 Holloway Drive, Bayswater, Vic. 3153 Australia Ph: 613 (03) 762 5777 Fax: 613 (03) 762 9197 Is Your Product Or Service Getting The Exposure It Deserves? Consumers need to see your product if you want them to buy it Contact Paul To Reserve This Space (02) 982 9553 Convenient XY operation tor measuring phase differences between two waveforms Variable sweep control incorporating x10 magnifier Unca/ and trigg"/Jr warning lights TV-V & TV-H triggering Trigger hold-off High sensitivity- 1mV/div Stable low drift design 8 divisions of displayed dynamic range with accurate distortion-tree waveform measurement Special TV sync separation circuits tor measurement of video signals Delayed sweep function (OS7040A) ±3% accuracy OS7020A $650 ex tax $733.58 Inc tax• 0S7040A $1045 ex tax $1243.55 inc tax• • Cursors tor direct measurement of waveform voltage, time and frequency • 20MHz bandwidth • 1mV max sensitivity • Similar performance to OS7020A 0S8020R $1045 ex tax $1243.55 Inc tax• Supported & Serviced Australia-wide by Elmeasco Instruments Pty Ltd N SW (02) 736 2888 Vic (03) 879 2322 Old (07) 875 1444 S.A. (08) 344 9000 W.A. (09) 470 1855 You've Gotta Getta Go/dstar from : A.C.T. John Pope Electrical80 6576N.S.W. D.G.E. Systems (049) 691625eW.F.Dixon(049) 69 5177 • Macelec (042) 291455 • Newtek (042) 271620 • Novacastrian Electronic Supply (049) 62 1358 e Obiat Pty Ltd 698 4776 e Digitel 709 651 1 e Geoff Wood 427 1676 N. nRRITORY J Blackwood (089) 84 4255, 52 1788 e Thew & Mccann (089) 84 4999 QUEENSLAND St Lucia Electronics 252 7466 • B.A.S. Audiotronics 844 7566 • The Electronics Shop (075) 32 3632 • Solex (Townsville)(077) 72 4466 • Xanthos Electrical (079) 27 8952 S.AUSTRALIA Force Electronics (08) 212 5505 VICTORIA G.B. Telespares 328 4301 e The Electronic Components Shop 670 64 74 • Facto Controls (052) 78 8222 • Mektronics 587 3888 • Truscott Electronics 723 3094 W AU TRALIA Atkins Carlyle 481 1233 • Leda Electronics 361 7821 PAPUA NEW GUINEA TE (P.N.G.) Pt Moresby 25 6322 Lae 42 6246 ·Recommended prices only * FINANCIAL SUBSCRIBERS ON 12TH DECEMBER WILL BE INCLUDED OVER $6500 WORTH OF PRIZES MUST BE WON Bose's radical new Lifestyle Music System is the great prize to be won. It comprises the Music Centre and one RF remote control (pictured), the Bose Acoustimass Powered Speaker System and a pair of Bose Lifestyle Powered Speakers (pictured). By taking out a subscription you could enjoy the benefits of this radical new music system which does not clutter up your living space with bulky hifi equipment and enables you to listen to two program sources at the- same time, in two zones, in your home. OFFER ENDS 30TH NOVEMBER 1990 30 SILICON CHIP - TM ® PLUS EACH MONTH ONE PAIR OF HIGH PERFORMANCE BOSE 101 MUSIC MONITOR SPEAKERS 3 SUBSCRIPTION PACKS FROM SILICON CHIP As part of this promotion, one pair of Bose 101 Music Monitor speakers, valued at $450, will be given away each month to a lucky subscriber. And even if you do win a pair of these speakers, you still go into the draw for the Bose Lifestyle Music System. Also each month, 3 new subscribers will get a SILICON CHIP subscription pack for free. This comprises a one year subscription to SILICON CHIP, one SILICON CHIP binder and one SILICON CHIP T-shirt in your size. Effectively, you get your annual subscription fee of $42 back and still go into the draw for the Bose Music System. HOW TO ENTER All current subscribers to SILICON CHIP at 1 2th December 1 990 are already in the draw. By taking a further one or two year subscription, they get another one or two entries . New subscribers enter by filling out the subscription coupon elsewhere in th is issue and sending it together with their remittance of $42 (cheque, postal note or credit card authorisation) to SILICON CHIP, PO Box 139, Collaroy, NSW 2097. Or fax it with a credit card authorisation to (02) 979 6503 . (1). The eompet111on 1s open only to Australian residents with a cur rent_ ren ewed or extendecl subsc r1pt 1on received by the last mail en 30th November 1990. (2) Subscribers extending fo, an add1tmnal year are entitled to two entries. (3). Subscriber s wi th a two year subscJ1ptmn are ent itled to '.wo entries (4) Entrles reGe1ved after the closing da{e wil l not be included . (5) Employees of S11leon Chip Pu!Jl1ca l 1ons Ply Ltd ,rnd Bose Australia lnG and their families are not el lg1ble to entei {6) . Sou tt1 Aust1 a!1an residents do not tiave to pu rn t1a se a sub f>cr1p t10n to enter but may enter only oner, by submitting th eir mime . ad RULES & CONDITIONS di ess ana a hand drawn laes1m1le ol the subscnpt10n to Silicon Ch ip Pubhcatmns Plv Ltd. PO Box 139. Collaroy. NSW 2097 (7). Prize s are not tran sferable or exchangeable and may not be con verted to cas t1 (8j. l he Judge s dec1s1on ,s finc1 I and no conespondence will be entered into (9 ) The description ol the compet It t0n and mstructIons on how 10 enter form a part of the co mpetItIon cond 1t1or,s (10) The com-petllon beqms on 29th Auq ust 1990 and closes with the last mail on 30th Novem ber. 1990. The draw will take place in Sydney on 171h December. 1990 and lhe winner will be notified by lettergram . The winner w1E also be announced in The Australian on 20th Decembe1 , 1990 and in a late1 issue of SIucoN CHIP. (1 1). The maIor prize Is one Bose Lifestyle Music Syslem and the total value of all prizes offe red is $6735.00 . The prnmoter is Silicon Cl11p Publ1cal1ons Ply Ltd . UnII 39/5 Ponderosa Parado . Warriewood NSW 2102 Perm ii TC90l2565 issued under the Lotteries and Art Unions Act. 1901: Raffles Bingo Permit Board Permit 90/1668 issued on 16/8/90 . ACT Permit No 90/1077 issued under the Lotteries 01 · dinanc e. 1964. NT Perm it NT093 4/ 90 issued under Lotteries and Gam ing Act NOVEMBER 1990 31 Build the SurfSound Simulator If you often come home from work a bit frazzled, then you need the SurfSound Simulator. It produces the soothing sounds of waves rolling up your favourite beach. ~ · ··c;;cOCccC::.,.,q,,•..•,:.;; By DARREN YATES Most of us at one time or another have wanted to own some property on the beach. Just think-you come home from work, throw your trusty towel over your shoulder, and go for a swim in the "backyard". Or, if you prefer, you can just sit on the sand and listen to the waves rolling up on the shore, while you improve your tan! Unfortunately, most of us can't afford lhe price lags lhal go with such land. Nevertheless, the sounds of the surf do contain a relaxing, rhythmic quality about them - just the thing to unwind those nerves after a hectic day's work! It's also great if you have trouble getting to sleep at night, or any other time of the day. The SurfSound Simulator is the next best thing to owning a bit of that favourite beach and is half a million dollars cheaper into the bargain! It produces a sound that actually imitates the ebb and flow of the surf rolling up on the beach, including the occasional big 24 SILICON CHIP "dumper" that comes and drenches your towel - except in this case, you get the surf sound without the salt sea spray. The project uses no "hard to get" bits and fits neatly into a small plastic instrument case. If you have a reasonable junk box, you probably have most, if not all, of the parts already. The SurfSound has its own builtin speaker, or you can use the RCA socket at the back and feed the sound into your stereo system for an even more realistic effect. It runs off a 12VDC plugpack so you don't have to worry about mains wiring and it requires no setting up to get it to work. All you do is turn it on, set the volume and you're away. OK, enough of the hard sell! Let's take a look at how the SurfSound actually works. Block diagram To start with, let's look at the block diagram in Fig.1, which shows each of the different sections in the circuit. This will make it easier to understand the circuit diagram later on. The sound of the surf is very similar to white noise. That's the sound you hear coming out of your TV when you're not on a particular channel. We can generate that noise quite easily using a single transistor. However, because the surf doesn't have a constant volume, we have to find some way of varying the volume or "modulating" our noise source. By doing this, we can imitate the ebb and flow of the surf. If you sat down and plotted the sound level of the surf over a period of time, you would find that it resembled a triangular waveform. The sound steadily increases, hits its peak and then dies away again. In the block diagram, you'll see that there are not one but two triangle wave generators. The reason for this is to provide a degree of randomness to the sound level. With one generator, you only get the same wave crashing at a constant rate but with two, you get two waves rolling in at random. Both waveform outputs are fed into seperate modulators. To keep the circuit using only common parts, we used the humble diode to provide the modulation. We'll talk about how this is done a little later. The output from generator 1 is also fed to a peak amplifier. This amplifies the peak of the waveform to give a larger DC voltage than the triangle wave generator can produce. When we feed this voltage into another diode modulator, we produce the big "dump" when the wave hits the beach. All three diode modulators are capacitively coupled to the inverting input of an op amp stage. In operation, the three modulators vary the impedance from the op amp's inverting input to ground, thus changing the gain and therefore the sound level. The output of the preamplifier is fed to a low pass filter stage. Its job is to add realism to the sound by reducing the high frequency response. From there, the signal then passes to the power amplifier and thence to the loudspeaker. The circuit Refer now to Fig.2 which shows all the circuit details. The noise source is Ql which is a reverse- The Surfsound Simulator is built into a standard plastic instrument case. Notice the pattern of holes drilled into the lid to allow sound from the loudspeaker to escape. You can also feed the output into your hifi system. biased BC549C NPN transistor. Because the base-emitter junction of a transistor is very much like a zener diode, it suffers the same breakdown effect when a voltage is placed across it, thus producing a good source of white noise. This noise is capacitively coupled to the non-inverting input (pin 3) of op amp stage IC2a. ICla & IClb together form the first triangle wave generator, while IClc & ICld form the second. The first generator is responsible for a wave that is very close while thesecond produces a wave that crashes in the distance. Because the two are nearly identical, we'll just explain how one of them works and mention the slight differences between the two. If we look at the first generator, ICla forms a Schmitt trigger while IClb is connected as an integrator. Because it is a Schmitt trigger, ICla's output will be either high or low and so it either charges or discharges the 33µF capacitor at pin 6 of IClb via Dl, D2 and the two associated resistors. The resulting waveform at pin 7 of ICl b will be a sawtooth which rises faster than it falls. This gives the effect of the waves rolling up faster than they run back to the sea. Now take a look at the second generator based on IClc & ICld. PREAMPLIAER NOISE SOURCE ,___ _ POWER AMPLIFIER LOW-PASS ALTER TRIANGLE WAVE GENERATOR 1 DIODE MODULATOR 1 TRIANGLE WAVE GENERATOR 2 DIODE MOIHJLA TOR 2 DIODE MODULATOR 3 PEAK AMPLIAER Fig.1: the SurfSound uses two triangle wave generators to drive three diode modulator circuits. These then vary the gain of an op amp stage which amplifies a noise signal fed to its non-inverting input. The output of this op amp drives a low pass filter stage and a power amplifier. OCT0BER1990 25 The only difference between the two circuits is that the second generator has a smaller char ging resistor (100k0 vs 220k0). This has two effects. First, it helps to make the two waves more random in nature and second, it provides the second wave with a faster " roll up" time. The 0.1µ,F capacitors at the outputs of ICl a and IClc r emove "clicks" from the audio output which would otherwise a ppea r due to the switching a ction of the Schmitt triggers. Diode modulators The outputs of the two triangle wave generators are used to drive the diode modulator circuits shown in the block diagr am (Fig.1). The circuit technique used here will probably be new to a number of readers so we'll go thr ough it in some detail. It relies on the fact that the conductivity of a diode varies with the voltage across it; ie, a diode that has 0.6V across it will conduct more current than one with only 0.2V across it. There are thr ee modulators in the circuit, centred around diodes D5 to DB (diodes D5 and D6 run from the same point and so are counted as one modulator). The first generator drives diodes D5 and D6, the second drives D7 and the. peak amplifier operates DB. Again, each of these is similar in operation, so we'll only describe one in detail. On the cathode lead of each of these diodes is a voltage divider. In the case of D7, for example, there is a pair of 100k0 r esistors. These set the offset voltage for this modulator to 6 volts. Different r esistance values a r e used in the voltage dividers of the other modulators. These set the offset levels to different values to ensure the correct turn-on sequence. For diode D7, this means that the output of its triangle wave generator must rise above 6V before the diode has enough foward bias to conduct. This output is coupled to the anode of D7 via a 47k0 resistor and also to the inverting input of preamplifier IC2a via a 0.12µ,F capacitor. While the voltage from ICld re- PARTS LIST 1 plastic instrument case, 150 x 160 x 65mm 1 PCB, code SC08109901 , 140 x 120mm 1 front panel label, 142 x 55mm 1 rear panel label, 142 x 45mm l 1 OkO log potentiometer 1 knob to suit 1 screw-mounting RCA socket 1 2. 1 mm DC power socket 1 5mm LED bezel 1 SPST toggle switch 5 PC pins 1 1 2V DC plugpack 4 clamps for loudspeaker (see text) 1 4-inch car speaker (Jaycar Cat. AS-3008 or equivalent) Semiconductors 2 1 1 1 1 8 26 LM324 quad op amps (IC1-,2) 7812 3-terminal regulator BC549C NPN transistor (01) BC338 NPN transistor (02) BC328 PNP transistor (03) 1 N91 4 silicon signal diodes (D1-D8) SILICON C HIP 1 5mm red LED (LED 1) Capacitors 3 1 2 2 1 1 1 1 2 5 1 1 1 4 70µ,F 16VW PC electrolytic 330µ,F 25VW PC electrolytic 100µ,F 16VW PC electrolytic 33µ,F 25VW PC electrolytic 1 Oµ,F 63VW PC electrolytic 1 Oµ,F 25VW PC electrolytic 2 .2µ,F 25VW PC electrolytic 0 .47µ,F 63VW PC electrolytic 0.12µ,F metallised polyester 0. 1 µ,F metallised polyester .056µ,F metallised polyester .018µ,F metallised polyester .0012µ,F metallised polyester Resistors (0.25W, 5%) 1 1MO 2 330k0 1 220k0 1 150k0 9 120k0 1 5 1 OOkO 4 68k0 3 2 1 1 2 1 2 47k0 33k0 1 2k0 8.2k0 4.7 k0 1 kO 10 Miscellaneous Hookup wire, solder, screws, nuts, washers etc. mains below 6V, the diode is reverse-biased and the 0.1 2µ,F capacitor sees a large impedance to the ground line. However, when the voltage rises above 6V, the diode begins to turn on, which decreases its AC impedance. The 0.12µ,F capacitor thus sees a progressively lower impedance to ground as the voltage across the diode increases. Because op amp IC 2a is connected as a non-inverting amplifier, these impedance variations directly control its gain. If the impedance goes down, the gain goes up. Conversely, if the impedance goes up, the gain goes down. Thus, the diode modulators control the gain of the preamp stage to vary the sound leveL When the voltage across D7 reaches 0.6V, the diode appears as a short circuit to the capacitor and the impedance to ground is now set by the 8.2k0 resistor connected to D7's anode. The 100µ,F capacitor, in conjunction with the 8.2k0 resistor, forms a high-pa ss filter which rolls off the response below O.lHz. D5 and D6 work in similar fashion but have offset voltages of 5.45V and 7.2V respectively. Note also that D6 controls another highpass filter. This consists of a 4.7k0 resistor and 0.1µ,F capacitor, and has a cutoff frequency of 340Hz. Because of their different offset voltages, D6 comes into operation before D5 (which controls lower frequencies) so that we get a realistic "whooosshhh" sound as the wave breaks. Peak amplifier In addition to the above, the gain of IC2a is also controlled by diode modulator DB, which is driven by peak amplifier IC2d. This in turn is driven from the output of ICl b . The bias for IC2d's inverting input (pin 13) is set to about 7V by the 33k0 resistor & the two 100k0 resistors. Thus, the output of IC2d remains low until pin 7 of ICl b Fig.2: the circuit .includes all the elements shown in Fig.1. ICla,b & IClc,d are the triangle wave generators, IC2d the peak amplifier, & D5/D6, D7 & D8 the diode modulators. The latter vary the gain of IC2a which amplifies noise signals from Qt. ► N "-I 0 ...... c.o c.o ::0 t'1 tJ:j 0 '-l n 0 I 120kt 120kS +12V ~ +12V I I V" . ........ •1?V I ® 03 47k 330k hh u u 100k +12V ":' • -. + 33 25VW 100kt •PM 33k I .• r-...... l +m~ 100k - I ,,.-:-.. 01l D I I .~7k 150k4 100k! .J: (!) ":' I I 100 16VWL. + 68k 100k +12V~ OU 100k + ---+ 0.47 63VW D.1-+ I 1 +12v -- 8 I VIEWED FROM BELOW EQc .J.:' 330 25VW+ .. l r -! 120k I ,,.,,.,.,. 68k 100 16VWJ D5 ...11/" l I I I - - 0.12 I I I VOLUME VR1 10k GNO ,~oo, ~. .,. l ·--··_r ""t, ~ I ~ + 0.1+ I .018! rn E 02 BC338 ~ I B -'=K .,. Sil SPEAKER +12V ·1 470 16VW +12V ~OUTPUT l I I + I 16VWJ 470 IN~OUT I --····· SURFSOUND SIMULATOR ov-¼ 0 V~ ~,,. I J: 2.2 25VW+ k - ~ +12V DC PLUGBACKO--O .0012 1.----J 1M +12V CAPACITOR CODES OUTPUT S1rs---(r-:112VDC l;J' ~ + ~ 0 ~INPUT - g :f ~ _...; ''""~ ~ "' D 30 · 33uF ~. , ~ \..I ~ ~0.47uF W 0 Value IEC Code EIA Code 0.12µF 0 .1µF .056µF .018µF .0012µF 120n 100n 56n 18n 1 n2 124 104 563 183 122 adds to the realism of the sound. After that, the signal is passed onto the RCA socket and also to a lOkQ volume control pot which feeds the internal power amplifier. IC2c, Q2 and Q3 form the power amplifier stage. Q2 and Q3 buffer the output of the op amp to provide current gain and are connected into the feedback loop to reduce crossover distortion. Power for the circuit is derived from a 12V DC plugpack supply. This feeds a 7812 3-terminal regulator which in turn delivers a regulated 12V rail to feed the op amps. The 470µF and O. lµF capacitors provide filtering for the regulator while LED 1 provides visual indication that the power is on. Note that although the plugpack supply delivers a nominal 12V output, its output will actually be much higher than this typically 16-17V. This is quite sufficient to drive the 7812 regulator. Construction A VR1 LED1 Fig.3: be sure to check component orientation carefully when wiring up the PC board. Note that the 0.1µ.F capacitor between IC1 & IC2 should be laid flat on its side to provide clearance for the loudspeaker. reaches this threshold level. At this point, IC2d amplifies the signal to produce a faster, steeper waveform. This produces the big "dumper" that crashes onto the beach. Low-pass filter IC2a amplifies the white noise generated by Ql. From there, the signal is fed to IC2b which functions as a non-inverting amplifier 28 SILICON CHIP with a gain of 11. A .0012µF capacitor in the feedback loop of IC2a rolls off the response above 130Hz, while the 2.2µF capacitor in the feedback network of IC2b rolls off the low frequency response of this stage below a few Hertz. Following IC2b is another lowpass filter stage consisting of a 4.7k0 resistor and lOµF and 0.018µF capacitors. This further reduces the higher frequencies and Most of the components for the SurfSound are mounted on a PC board coded SC 08109901 (140 x 120mm). This is housed in a standard plastic instrument case measuring 160mm deep, 150mm wide and 70mm high. Before you commence assembly, carefully check the PC board for shorts or breaks in the tracks. Any faults should be corrected at this stage. Once you're satisfied with this, take a look at the wiring diagram [Fig.3). It shows how the components should go in. Begin by installing PC stakes at all the external wiring points on the board. Once this is done, you can install the wire links, resistors and diodes, in that order. Make sure that each diode is correctly oriented. If you are unsure of the colour The PC board is screwed to integral pillars in the base of the case while the loudspeaker is secured to the lid using four aluminium clamps (see text). Note the 7812 regulator - its tab faces the front. coding of the resistors, use a multimeter to check the values. The next step is to to install the polyester (greencap) capacitors. Note that the O. lµF capacitor between ICl & IC2 should be laid flat against the board (ie, bend its leads at right angles) so that there is sufficient clearance for the loudspeaker. Once you've got this done, solder in the electrolytic capacitors but make sure that you've got the polarity correct. Finally, install the transistors, I Cs and 3-terminal regulator. Again, make sure that they are installed correctly, then check over the board again in case you missed something. In particular, check that the correct transistor type has been installed at each location. Now attach the Dynamark labels to the front and rear panels, then drill and ream out the mounting holes. The only hole that may cause difficulty is the hole for the DC power socket. The best way to get the hole size just right is to drill a small pilot hole and then use a tapered reamer to enlarge the hole until it's slightly smaller than the perimeter of the socket, Finally, the hole can be filed to shape until you RESISTOR CODES D D D D D D D D D D D D D D D No 1 2 1 1 9 15 4 3 2 1 1 2 1 2 Value 1MQ 330kQ 220kQ 150k0 120k0 100k0 68k0 47k0 33k0 12k0 8.2k0 4 .7k0 1 kQ rn 4-Band Code (5%) brown black green gold orange orange yellow gold red red yellow go1d brown green yellow gold brown red yellow gold brown black yellow gold blue grey orange gold yellow violet orange gold orange orange orange gold brown red orange gold grey red red gold yellow violet red gold brown black red gold brown black gold gold 5-Band Code (1%) brown black black yellow brown orange orange black orange brown red red black orange brown brown green black orange brown brown red black orange brown brown black black orange brown blue grey black red brown yellow violet black red brown orange orange black red gold brown red black red brown grey red black brown brown yellow violet black brown brown brown black black brown brown brown black black silver brown OCTOBER 1990 29 ~S~4- BOARD SOLUTIONS Pty Ltd EXTERNAL FLOPPY DISK DRIVES 10MHzXT,(640K)OKRAM M1010 115.00 10MHzXT,(1MB)OKRAM M1000 149.00 31 MHz XT286 OK RAM M1020 225.00 Baby 286 12MHz OK RAM M2015 399.00 Baby 286 12MHz OK RAM VLSI M2030 449.00 Baby 286, 12MHz VLSI OK Neat M2020 499.00 286, all-in-one, OK RAM M2010 545.00 16MHz NEAT 286 OK RAM M2040 599.00 20MHz 2~6 OK RAM M2045 845.00 16MHz 386SX, OK RAM M3000 895.00 25MHz 386, 32K Cache, OK Neat M301 o 1995.00 33MHz 386, 32K Cache, OK M3 o2 o 2795 _00 ,------------------------., I· CHIPS 1M RAM Chip - 100nS 1M RAM Chip - 80nS 256K RAM Chip - 1OOnS 256K RAM Chip - sons 8087-2, 8MHz Co-Processor 29300 29380 29400 29480 29500 29.95 32.95 7.95 8.95 275.00 4X256KRAMChip, 100nS 29200 4 X 64K RAM Chip, 120nS For . 29212 VGA card 64K RAM Chip - 120nS 29112 NEC V20Chip 29000 NEC V20 Chip, 10MHz 29010 29020 NEC V30 Chip, 10MHz 64K RAM Chip - 1OOnS 29210 80387SX 16MHz Co-Processor 29540 64K 1OOns RAM Chip 29210 2C87-8MHz (equiv 80287/8) 29550 2C87-10MHz (equiv 80287/10) 295Sb 2C87-12MHz (equiv 80287/12) - zg-550 29565 2C87-20MHz 29570 3C87-16MHz (equiv 80387/16) 3C87-20MHz (equiv 80387/20) 29575 3C87-25MHz (equiv 80387/25) 29580 3C87-33MHz (equiv 80387/33) 29585 SIMM Module, 1MB 80ns 29680 SIPP Module, 1MB 80ns 29690 32 .95 12.00 4.95 24.95 39.95 49.95 5.45 795.00 5.45 449.00 495.00 549.00 649.00 649.00 749.00 949.00 1099.00 295.00 295.00 XT (8088) 10MHz System XT (8088) 31MHz System 286-12 (80286) System 286-12 (80286) VLSI System 286-12 (80286) NEAT System 286-20 (80286) 20MHz System 386SX (80386SX)16MHz System 386-33 (80386) 33MHz System I 895.00 1095.00 1225.00 1595.00 1695.00 2050.00 1995.00 4795.00 All systems are fully bullt and tested, with RAM fitted. Simply add the video card and monitor of your choice. 12 months warranty applies to all Board Solutions Systems. INTERNAL FLOPPY DISK DRIVES YE-Data 360K YE-Data, 720K/1.44M D3000 drive Plus Frame YE-Data, 1.2MB I. X1010 X1030 X2859 X2861 X2860 X2862 X3861 X3863 D5500 D3000 D301 O D5510 149.00 184.95 199.00 175.00 INTERNAL HARD DISK DRIVES NEC 42MB, 28mS 3.5in D8000 plus Frame M'scribe 40MB AT BUS 3.5in Kalok 20MB 40mS Seagate 20MB ?Oms RLL inc XT controller. Seagate 20MB 65ms RLL inc XT controller Seagate 30MB 65ms MFM incXT controller Seagate 40MB ?Oms MFM inc XT controller Seagate 5.25in 40MB 40ms RLL Seagate 5.25in 40MB 28ms RLL Seagate 5.25in 65MB 40ms RLL Seagate 5.25in 65MB 28ms RLL Seagate 42MB 24ms VIC I For Amiga 500, 1000, 2000, 3.5in 880K For Amiga 500, 1000, 2000, 5.25in 360/880K For Commodore PC1, 5.25in 360/720K 40/80 track For Atari.ST series, 3.5in 720K For Atari ST series, 5.25in 3601720K 40/80 track For Amstrad PC1512/1640 , 3.5in 720K For IBM XT, 3.5in 720K XT For IBM AT, 3.5in 1.44MB For IBM XT, 5.25in 360K For IBM AT, 5.25in 1.2MB For TOSHIBA laptop series, 5.25in 360K For TOSHIBA laptop series, 5.25in 1.2MB D9500 249.00 D9510 299.00 D9520 D9530 299.00 299.00 D9540 299.00 D9550 D9560 D9570 D9580 D9590 269.00 299.00 329.00 299.00 329.00 D9600 349.00 D9610 399.00 I. .._I____________ _. MICE & JOYSTICKS D8000 D8010 D8020 D8100 745.00 775.00 795.00 399.00 D8200 529.00 D8210 575.00 D8220 629.00 D8230 D8240 D8250 D8260 D8270 D8390 675.00 775.00 795.00 849.00 899.00 849.00 Joystick PC/XT/AT 3 Button Serial Mouse Mouse Mat J1000 J1030 J1040 34.95 69.95 7.50 I MONITORS Monitor, Monitor, Monitor, Monitor, Monitor, Monitor, I 14in TTL, Amber 14in TTL, Green 14in TTL, Paper White 14in EGA 14in VGA 14in Multisync M9000 M9010 M9020 M9030 M9040 M9050 249.00 249.00 249.00 599.00 749.00 ____.., 899.00 MICRO CHANNEL Dual Sync Adaptor, PS/2 2MB RAM Card, PS/2 OK RAM 8MB RAM Card, PS/2 OK RAM PHONE OR FAX NOW FOR LATEST PRODUCTS. PRICES AND INFORMATION OOPS! OVERSTOCKED ALL-IN-ONE "AT" MOTHERBOARD: SLASHED BY $100 - ONLY WHILE THEY LAST! J_Iere 's a sensational bargain - if you're quick! We're dramatically overstocked on these superb '286 motherboards which include serial and parallel ports and hard/floppy controller on board. Update your old XT snail to AT performance! Normally fantastic value at $545.00; Our ~uppli~rs have re~lly, because we're overstocked we've done It this t~me: th~y didn t slashed the price - only while stocks see the ~ec1mal pomt and last - by a massive $100.00 I MC1000 299.00 MC1010 349.00 MC1020 599.00 WHATA BOO-BOO! sent ten times our order. Our difficulty is your opportunity: YOU REAP THE BENEFIT! HURRY! THIS MONTH ONLY OR UNTIL CURRENT STOCKS SOLD! RAM CARDS I/O CARDS 2 Ser. 1 Parallel Games, Parallel & 2 x Serial Chip Set & Cable suit 11040 Multi 1/0 Card XT only Multi 1/0 Card, 2 Ports all 4 drive types supported (XT Only) Parallel Printer Card (XT/AT) Serial PortCard X 1 (XT/AT) Serial PortCard X 2 (XT/AT) 1/0 Plus Card - XT Only Serial/Parallel Card - XT/AT 2 Serial, 2 Parallel, AT Games, Par, Serial XT/AT Multi-Serial Card, 4P-AT I 74.95 99.95 29.95 129.00 i1010 i1020 i1030 i1040 i1050 i1060 i1070 i1080 i1090 164.95 29.95 54.95 69.00 99.00 64.95 84.95 89.00 245.00 VIDEO CARDS VGA Card, 800 x 600 (256K) VGA Card, 1024 x 768 (512K) Magic Combo CGA Card EGA Card Mono Hercules Card, 16MHz operation + Parallel Port I i1080 i1110 i1041 i1000 V1000 V1010 V1020 V1035 299.00 399.00 129.00 179.00 V1040 99.00 POWER SUPPLIES 200 Watt PSU Suit Tower Case 200 Watt PSU Suit Baby T Case 150W PSU, Circuit Board 150W Switching PSU - XT 200W Switch PSU - Baby AT 200W PSU, Baby AT, L Type 220W Switching PSU -AT 200W PSU With Battery Backup 150W PSU Cap. 220nF/200V I P2020 P2030 P1500 P1510 P2000 P2010 P2200 P2040 P9000 195.00 149.00 85.00 124.00 149.00 149.00 195.00 695.00 3.95 KEYBOARDS 84 Key Keyboard XT/AT 101 Key Keyboard, XT/AT 101 Key Keyboard + TrackBall K1000 K1010 K1020 95.00 115.00 199.00 RAM Card, OK RAM, XT only 2MB RAM Cd, OK LIM/EEMS AT 2MB RAM Cd, OK LIM/EEMS XT 6MB RAM Card, -OK RAM 4MB Fast Card Suit 20MHz +SX 32 Bit RAM Card 25 +33MHz R1000 R1010 R1020 R1030 R1040 R1050 INTERFACE CARDS 99.00 265.00 245.00 295.00 299.00 349.00 DISK CONTROLLER CARDS Floppy Disk Card, 4 Ports 360K Disk Cont 4 port, 2In 2Ex or 4In Floppy Disk Card All Drives ESDI Hard Disk Cont Card - AT ESDI HDD/FDD Card - AT Hard Disk Cont, 1:1 lnt. AT HDD/FDD Cont, 1:1 lnt. AT Hard Disk Cont,1 :1 lnt. RLL, AT HDD/FDD Cont, 1:1 int, RLL, AT SCSI HDD/FDD for AT Hard Disk Controller, XT Hard Disk Controller, RLL-XT I E1000 E1030 E1010 E1040 E1050 E1060 E1070 E1080 E1090 E1105 E1110 E1120 I 55.00 134.95 99.00 349.00 425.00 245.00 275.00 249.00 285.00 275.00 134.95 154.95 CASES Hinged, Baby AT Full Size Hinged AT Gas~ Hinged Baby ATw/200W PSU Slimline 'XT' or 'AT' with PSU 3.5in Hard Disk Ext. + Cable 5.25in Floppy Disk Ext. + Cable 5.25in Full Height Ext. + Cable 5.25in Mount for 3.5in Drive Baby Tower Case AT Baby Tower Case+ 200W PSU Tower for 6 Dev. (4 front, 2 rear) Tower for 6 Dev. (4 front, 2 rear) & 200W PSU Tower for 6 Devices, (6 front) Tower for 6 Devices, (6 front) + 200W PSU Case, hinged XT C1000 139.00 C1005 . 199.00 C1010 249.00 C1020 275.00 C1030 99.00 C1040 115.00 125.00 C1050 C1060 25.00 C1070 189.00 C1080 325.00 C1090 399.00 C1100 C1120 549.00 399.00 C1130 C1140 549.00 95.00 48 Line 1/0 Card F1130 Serial RS-422 Adaptor F1140 Industrial 1/0 Card F1150 Universal Wire-wrap Card F1030 Dual Serial RS-422 Card F1040 80286 Speed-up Card F1050 IEEE 488 Interface Card F1060 IEEE 488 Interface Card- National Compatible F1070 A-D/D-A Converter, 12 brr, 1 Ch. F1080 A-D/D-A Converter, 12 brr, 2 Ch. F1090 Clock Card - XT F1100 EPROM Writer Card F1110 Games Card- 'XT'& 'AT' F1120 110.00 135.00 445.00 125.00 195.00 495.00 445.00 595.00 199.00 599.00 49.95 245.00 35.00 NETWORK BK Ethernet 8 bit with T Adaptor 16K Ethernet 16 bit with T Adaptor Ethernet 50 Ohm Terminator Thin Ethernet Cable, 25 feet Thin Ethernet Cable, 50 feet Thin Ethernet Cable, 75 feet Auto Boot ROM for NEE1 Workstation, 12MHz Diskless, with 1MB RAM N1000 399.00 N1010 N1 020 N1030 N1040 N1050 N1060 449.00 12.75 35.00 49.00 62.00 79.95 N2000 1695.00 CABLES I OH NO! We've run out of room to show you our great range of cables, connectors and gender benders. For details of any of these products, call Board Solutions today. No obligation, of course! PHONE OR FAX NOW FOR LATEST PRODUCTS. PRICES AND INFORMATION MAJOR AUTHORISED DEALERS Adelaide Broken Hill Cannonvale Charlestown Gotts Harbour Devon port Glen Innes Hobart lnverell Ipswich Leeton Lightning Ridge Lismore Mackay Morwell Mount Gambier Mt Isa Mudgee Nambour Narrabri Port Lincoln Townsville WaggaWagga Windsor Microtronics Hobbies And Electronics Nth. Qld. Adv. Technology Newtronics Gotts Harbour Electronics Al Electronics John Sommerlad Electronics Beta Electronics lnverell Computer Bits ACR Computers Leeton Audiotronics Cycle & Sound Decro Electronics Steven's Electronics Morwell Electronics Hutchesson's Communic. Outback Electronics Headware Nambour Electronics Namoi Computers Bassham's TV & Computer Super Solex Phillip's Electronics Windsor Communications 2121799 884 908 466 898 439 600 525 684 248 322 323 661 348 232 223 769 281 6155 532 081 290 579 214137 511 723 346133 250 400 433 475 723 895 41 1 604 923 274 822 788 724 466 216 558 775 935 NEW DEALERS REQUIRED IN BRISBANE, DARWIN, MELBOURNE AND HOBART. PLEASE CALL ! • 14 Day money-back guarantee (except software) • At least 6 months warranty on all our products. • Mail orders are our speciality! • Road Freight on normal size items is $9.00 • Insurance $1.00 per $100 of order value • All prices INCLUDE sales tax • We accept Visa, Bankcard, Mastercard and Post Office COD • Call for latest price list • Special prices apply until September 31, or while stocks last! • Leasing facilities available: just ask! • Government pricing available on request BOARD SOLUTIONS IS YOUR ONE-STOP PC ENHANCEMENT COMPANY ~SH«d 4- 8OARO SOLUTIONS PO BOX 1120, LANE COVE NSW 2066 TEL (02) 906 5696 FAX (02) 906 4592 r: 7 0 ◄ 0 w 2 :::J ...J 0 > C a: Zo ::::, 1- ,... 0 c::c 0 Cl) ..J O') O') LL ::::, 0 ,... a:~ CX) ::::, 0 - Cl) i(/) 0 Cl) a: w 3:: 0 0 Q. __J JI r 1un11 7 OFF 12V DC IN POWER ON Fig.4: here are actualsize artworks for the PC board & the front & rear panels. AUDIO OUTPUT _J L can just squeeze the socket in. Be very careful not to make this hole too big, otherwise you won't be able to install the mounting screws. The holes for the mounting screws will have to be countersunk slightly so that their threads protrude through the socket body. In order to install the internal speaker, you need to remove the centre mounting pillars from the lid 32 _J SILICON CHIP of the case. This can be done by using a large drill bit running at low speed. Too fast a speed causes the plastic to break and spin off in all directions. The only ones to leave are those adjacent to the sides of the case [see photograph]. Once this is completed, you need to drill a series of large holes in the lid for the sound to escape. The speaker is secured to the top of the box using four clamps. We made ours from scraps of 20 gauge aluminium and bent them slightly with a pair of pliers. Once they are screwed down, they provide a secure grip and prevent the speaker from slipping around. Finally, install the pot, the LED bezel and the remaining components and wire them up to the board, as shown in Fig.3. Run the wiring using light-duty hookup wire and take care with the connections to the LED. Testing If you're sure that everything is correct, you can now connect the 12V plugpack. Make sure that "positive" is the centre pin of the socket and the inside of the plugpack plug. If you measure the voltage of the plugpack, it should be about 16.5V volts, with ground on the outside of the plug. Next, switch on and turn up the volume. You should hear the roar of that first big wave crashing onto the beach and slowly flowing back into the sea. If not, check the output of the 7812 regulator IC and the supply pins of the ICs. They should all be at exactly 12V. If the supply voltage is correct and the circuit still won't work, switch off and check the circuit board for solder .splashes, missed solder joints and incorrect parts placement. If you have a CRO, use it to check that the triangle wave The rear panel of the SurfSound Simulator carries a DC power socket, a power ON/OFF switch and an RCA audio output socket. You will have to countersink the mounting holes for the DC power socket slightly so that the screws pass through the socket body inside the case. generators are operating correctly (pins 7 & 14 of IClb}. Also, check the outputs of IC2a & IC2d. The only control in the circuit that needs adjusting is the volume control. Depending upon its position, you can make it sound like a ANTRIM TOROIDAL TRANSFORMERS QUALITY TOROIDAL POWER TRANSFORMERS, MANUFACTURED IN U.K. NOW AVA ILABLE EX-STOCK AT REALISTIC PRICES. sheltered beach in the middle of summer or a raging storm in the middle of winter. Whichever you prefer , the SurfSound should provide you with hours of listening pleasure or at the very least a decent night's sleep! E-1 LAMINATED POWER TRANSFORMERS PCB MOUNT STOCK RANGE PCB mount ex-stock in sizes from 2.5VA to 25VA with secondary voltages from 2 x 6V to 2 x 20V. Triple output models also available for logic circuits. Chassis mount man ufact ured to order in si zes from 2.5VA to 1 KVA in E-1 and C core. CHASSIS MOUNT TO ORDER We are the largest ex-stock supplier of toroidal power transformers in Australia. Our standard range consists of the U.K. manufactured ANTRIM range in 10 VA sizes from 15VA to 625VA. All have a single 240V primary and dual secondary windings ranging from 2 x 6V to 2 x 55V. Our local manufacturing facilities supplement this range by manufacturing specials to order. Models are available from stock to suit most project kits. Comprehensive data sheets are available on request. Enquiries from resellers and manufacturers are welcomed. Prices are extremely competitive and generous trade discounts apply for quantity. HARBUCH ELECTRONICS PTY LTD 90 George St., HORNSBY NSW 2077 Phone (02)476-5854 OCT0BER1990 33 ELECTRONICSJAYCAR ELECl RONICSJAYL;AH t Lt(.; I HUNll..;~A Yl..,;AH t.U:.V I HUNl \.,.:).Jf\ f l,f\N C L CV I M Vl '4 1Vu.Jf'\ I V/"\n CLCV' 1nv 1~1\...,o,,,Jf"\ r VMn LLLV I nv1'41V-.Nn Iv,-,.,, LLL...,., , ,....,, -.,vv ..,,.., , ...,r .. , L. ...... ..., , , , ... . • • - · ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCA R ELECTRONICSJA YCAR ELECTRONICS J AYCAR ELECTRO NIC. ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS JAYCAR ELECTRONIC, ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCA R ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONI CSJAYCAR ELECTRONI CS JAYCAR ELECTRONIC: !ELECTRON g~~g~:g!nm111111mmmmmmmmmmmmmmm111111m11m11m11mmmmmm11mmmm11mmmmmm■m,mc: 1 li:i?:::·········· ················'···'''·"'·''······"·"'· ··'·''·'' ·" . ·' .) ....❖' .:,: :.', ,:::. · : : ···\' ·' : • • • • • · ·::: : :'··:·:: ••• '• .c:•.,: .. ~" :X•... ·: ... ., , ..': :·:::,. ··::: ·:, .,, ·»· ·" ,,.., ,, '" . .'" ! :. ' • '»....❖ ·: Jaycs~:~•Biog,o:r.:-;;!!!a,ms : I f,,.':,' !g~~g~:g! With Christmas just around the corner, burglaries will be on the increase. Don't let your home become a statistic. Install a Jaycar alarm now! ~g~g~:gs ~g~:g~:g~ ~g:g~:gs Key operated ::CTRONICS Cat LA-5162 cCTRON IC Alarm panels cCTRON ICS ECTRON IC ECTRONICS cCTRONICS ECTRONIC ECTRONICS ECTRONICS ECTRONICS ECTRONICS ECTRON ICS ECTRONICS ECTRONICS ECTRONICS ECTRONICS ECTRONICS ECTRONICS ·· ECTRON ICS :,:: $139 Keyless model Cat. LA-5168 $199 Keyless 4 sector Top of the rapge Cat. LA-5170 . e ..i Only $249 SAVE $16 Nonnally $265 Passive lnfrared detectors 11!1! Our best selling model Cat. LA-501 7 ECTRON ICS .,.. ECTRONICS .··..•.: ECTRONICS ECTRONICS ECTRONIC ECTRONICS ECTRONIC ECTRONICS ECTRONIC ECTRONIC ECTRONICS ECTRONICS ECTRONICS ECTRONIC ECTRONIC ECTRONICS ECTRONICS ECTRONICS ECTRONICS ECTRONICS ECTRONICS ECTRONICS ECTRONIC ECTRONICS .ECTRONICS .ECTRONIC .ECTRONICS ECTRONIC .ECTRONICS .ECTRONIC .ECTRON ICS .ECTRONICS .ECTRONICS .ECTRON ICS .ECTRONICS .ECTRONIC -ECTRONICS .ECTRONICS .ECTRONICS .ECTRONICS .ECTRONICS .ECTRON ICS .ECTRONICS .ECTRONICS _ECTRONICS .ECTRONICS .ECTRONICS _ECTRONICS .ECTRONICS _ECTRON ICS _ECTRONICS _ECTRONICS . ECTRONICS _ECTRONICS _ECTRONICS Nonnally $69.95 Save $10 Only $59.95 Terminator pulse count now with 5 year warranty Cat LA-5018 $99 The best PIR - pulse count !!!II I.. Cat. LA-5019 Save $20 Now $119 All alarm panels now have a 1 year warranty Alarm Panel Telephone Dialler Hom Speaker f0watt80 Cat AS-31 80 Cat. LA-5190 Save $70 Only $179 External Siren Cover Cat. LA-5110 j $23.50 * Normally $109.50 $17.95 Now Cat. LA-5070 $6.50 set ~ $32.95 Cat. LA-5160 116d8 wail 12V DC Cat LA-5255 Selectable normally open or normally closed at 150mA Cat IA-5300 Digital Access Keypad Tweety Pie Siren Reed Switch Magnet Assemblies Alarm Strobe Flash 12V DC larm Cable · 4 core .Bst per meter or $58 per 100 meter roll Cat WB- 1590 6 core $1 .25 per meter or $88 per 100 meter roll $89.50 Save $20 Cat. WB-1592 ffGI'c'r'l'l6" A ELECTRO 11....,-.:::,..JM.11..,,M.n C LCv rnut \lH.,;:>.J.I.\YI.., H t: Lt:L I HUNJ l,.::>JAYl.,A R R R R R ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA.YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCA R ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR n r, rr" Tn r \lo, 11,..1"' I A\.l,..A M r1 r,..Tn,•u 11r-t"' 11+.vrAn r:'I C r Tnru,ll r t:Lt:1..., IHU NI L,.:,..JA A ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR t. L,I ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONIC SJA YCAR ELECTRONICSJA YCA R C" IAVrAn Cl t:,..TD,a\Ul,..C" 111.vrAD C l c rTnru.11rC' 11+.Vl" A D 1( ELECTRONI CSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONI CSJAYCAR ELECTRONICSJAYCAR ELECTRONI CSJAYCAR ELECTRONICSJAYCAR ELECTRO NICSJAYCAR Cl crTDr"\ 11.11 ,..C' IAVr ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRO NICSJAYCAR ELECTRONICSJA YCAR ELEC TR ONICSJAYCAR ELECTRONIC ELECTRONIC ELECTRONIC ELECTRONIC ELECTRONI C A.o Cl crTD,"'\t.11r-c- 11+.Vl"' AD Cl CrTnl""\11.11 ,...C" 11+.vr,11.n C l C r" TDJ""\l. ll r , L LLv , n~rnv""", vMM CL Cv , nu"''-'" " " TvRM CL Cv I NUNIL,;:,.JA TL,AN 1:Ll:l, 1 HU NIL,:s.JAYCAH I ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR I ELECTRONICSJAYCAR ELECTRO NICSJA YCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR I ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR t: Lt:C 1HONICSJAYCAR ELECTRONICSJAYCA R ELECTRONICSJAYCAR ELECTRO NICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAH ELECTRONICSJA YCAR ELECTRONICSJAYCA R ELECTRONICSJA YCAR ELECTRONICS JAYCAR ELECTRONICSJAYCAR ELECTRONICS JAYCA R •:•:•·································································· ...................................................... . t lt:C I HONICSJA YCAR ELECTRONIC ELECTRONICSJA YCAR ELECTRONIC ELECTRONICSJAYCAR ELECTRONIC ELECTRONICSJA YCAR ELECTRONIC CAR ELECTRONIC IAYCAR ELECTROI IAYCAR ELECTROI IAYCAR ELECTROt IAYCAR ELECTROI IAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROt JA YCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI A YCAR ELECTROI IAYCAR ELECTROI AYCAR ELECTROI JAYCAR ELECTROI AYCAR ELECTROI AYCAR ELECTROI JAYCAR ELECTROt JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI AYCAR ELECTROt JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROt JAYCAR ELECTROI AYCAR ELECTROt JAYCAR ELECTROt JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI well as JAYCAR ELECTROI JAYCAR ELECTRO~ JAYCAR ELECTROI JAYCAR ELECTRO~ JA YCAR ELECTROI JAYCAR ELECTRO~ JAYCAR ELECTRO~ JA YCAR ELECTRO~ JAYCAR ELECTRO~ JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTRO~ JAYCAR ELECTRO ~ JAYCAR ELECTROI JAYCAR ELEClRO~ 'LIFE-GUARD' PETROL VAPOUR DETECTOR ATTENTION BOATING ENTHUSIASTS· THIS PRODUCT MAY SAVE YOUR LIFE!! MADE IN U.S.A. :!,ar:ar has done it a9!1in. We have made a scoop purchase of distress stock petrol fume detectors at a never to be repeated price. Model UA-zA This unit consists of cold sensor® detector (which is situated in the lilge) wiring loom and control unit/alarm. The control unit sits in a gymbal type bracket. It has an on-off-test switch alarm buZl!lr and light Both light and buzzer go off when fume concentration is still well below (20%) explosive level. The unit also includes a testing gas spray peak. This non-toxic non flammable gas allows you to test the system safely. No more dangerous petrol soaked rags! Draws 85 uA when operating so it is DK to virtually leave on indefinitely. Can be switched off when boat not in use. This unit sells in the USA for $!20 (US) but don't pay this much! Grab one now from Jaycar for only $39.95. That's rights 1/3 the US price. The local distributor sacrificed this stock to us so you would save! Now you have no excuse to protect you. your 1 family and expensive boat from the danger of a petrol explosion! I CatLA-5270 ONLY $39.95 Model GVM-50 This unit is permanently wired into your boat and does not contain a test switch. It's operation is automatic. It consists of an attractive cin:ular transducer. cold sensor® and testing gas. SellsintheUSAfor$70(US). Cat LA-5272 Jaycar'S price 10 YOU $24.95 Exclusive Cold sensor® Features - Detects gas instantly (no warm up) - Does not bum vapour for detection (intrinsically safe) • Detects gas above the upper explosive limit as well - Longest sensor life of popular types. - Unaffected by salt water and high humidity - Can detect rapid heat build up as well - Detects high bilge water - Endorsed by prestigious SWedish metals institute - Normally closed alarm will sound if wiring broken (fail-safe) Unique cold sensor<at> petrol fume detectors at a fraction of the nonnal price. - Up to 2/3 cheaper than USA! This product may save your life This microphone mixer is housed in a standard 15" rack mount box and operates directly from 240V AC. It has 5 inputs. 4 low impedance (600 ohm) and 2 high impedance (50k ohm). Each channel has its own volume control with a master volume control as well. it also incorporates a master bass and treble control. Microphone connections are on the rear panel via 5.5mm sockets. There is a high and low impedance output. Cat AM-4206 ~--· VIFA SPEAKER KITS - BACK IN STOCI(! Ne all know how fantastic the VIFA SA-Series speaker units sound. It would not be an exaggeration to say that they generally perform as 1uild equivalents that cost twice as much. tlFA SA-50 ! way kit ID watts RMS lull kit only $369 VIFA SA-70 2 way kit 50 watts RMS full kit only $449 VIFA SA-100 2 way kit 70watts RMS full kit only $699 VIFA SA-130 3 way kit 90 watts RMS full kit only $999 :at CS-2450/52 Cat CS-2471/72 Cat CS-2460~ Cat CS-2465/67 11 ;1~g1=~~~g:g~ JA YCAR ELEClRO ~ JAYCAR ELECTR O ~ JAYCAR ELECTRO~ JAYCAR ELECTROI JAYCAR ELECTRO~ JAYCAR ELECTRO~ JAYCAR ELECTRO~ JAYCAR ELECTRO~ JAYCAR ELECTRO~ JAYCAR ELECTRO~ JAYCAR ELECTRO~ JAYCAR ELECTRO~ JAYCAR ELECTRO~ JAYCAR ELECTRO~ JAYCAR ELECTRO~ JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTRO~ JAYCAR ELECTRO~ JAYCAR ELECTRO~ JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI JAYCAR ELECTROI !f1HM,l-fR'J~1<t~ ELECTRONJCSJAYCAR LE ':LECTRONICS JAYCAR ELECTRONICSJAYCAR ':LECTRONICS JAYCA R ELECTRONICSJAYCAR : LECTRONICS JAYCA R ELECTRONICSJAYCAR : LECTRONICS JAYCAR ELECTRONICSJAYCAR : LECTRONICS JA YCAR ELECTRONICSJAYCAR aECTRONICS . 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IA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR El FCTBQNICR IAYC AR ELECTRO YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR El FCJBQN)C~ IAYC AR I L NI Y L O NICSJAYCA R ELECTRONJCSJAYCA R ELECTRONICS ELECTRONI CSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJA YCAR ELECTRONICS ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTR O NICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS ELECTR ONICSJAYCAR ELECTRO NICSJA YCAR ELECTRONICSJA YCA R ELECTRONICSJAYCAR ELECTRONICS ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCA R ELECTRONICS ELECTRONICSJAYCA R ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS El ECIRQNICS IAYC AR FI ECIRONICS IAYC AR El FCIAOt,,IIC S IAYCAR.ELH"~TQnt,..u r ~ p Cl C C I QOt,llf"C ,Mn CLC.\., I n V l '41 \.,..:,,,JI"\ t V M n C L C\., I n V t '41 \.,.;:) VM I \., f"\n C.Ll:: V I n'IJl'III VOUM I V/"\ n CLCV I nVl'\111...,.:::>,JI""\ 1 \.,Mn l:.LC:.\J I nv1'4 1\.,.;:),,Jf"'\ I Vl"\n C:. LLV I n v t '' fl\.,.;J""' I '1,.,1"'\n C LCV I nV l '\11 \.,.:i..JI"\ I V l"\n C.LC V I nVl'\IIV..;>.JI"\ 1 \.,1"\n l:LC\., I n v , :AR ELECTRONICSJAYCAR ELECTTIONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAVCAR ELECTRO :AR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAVCAR ELECTRO :AR ELECTRONICSJAYCAR ELECTTIONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRO :AR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR CTR NI Y R CTR :AR ELECTRON! ::::::::::::❖·•··•·-.··························································...························································································································································································································•:•::::-::::-::::;:;:•:•··············· ·········· · · ··· ····· ··· ···· ······· ······················· ·· ····· · · ····· · ········ ·····•,;.•,••::::.: l ELECTRONIC ! ELECTRONIC Atlas!!! Asolarpoweredcalculatorwithbatteryback-upforwhenthere l ELECTRONIC ! ELECTRONIC m "European· 101 key keyboard for AT computers. Quality Philips brand. with sensitive soft touch keys. You isn·t enough light. Features a huge 22mm high digit display. positive action ! ELECTRONIC would normally be expected t'!fY well over $200 for this keyboard. keys and auto power off. ! ELECTRONIC Cat OC-7100 ! ELECTRONIC l ELECTRONIC Cat.XC-5092 ....___,.....,.._.__,.___._, l ELECTRONIC I ELECTRONIC& :~ Limitedquantityavailable ! ELECTRONIC ! ELECTRONIC ! ELECTRONIC ! ELECTRONIC ! ELECTRONIC ! ELECTRONIC ! ELECTRONIC ! ELECTRONIC ! ELECTRONIC ! ELECTRONIC That's right! we·ve done it again! With yet another scoop purchase. Alligator clips and EZ hooks in various ! ELECTRONIC ! ELECTRONIC& colours and sizes. To pass the savings on to you we have made packs of them: Primary 240V AC I ELECTRONIC& Secondary 14.BV AC l1ll 4.4VA. PC mount I ELECTRONIC& Limited quantity I ELECTRONIC& ! ELECTRONIC& Make up your own jumper leads! I ELECTRONIC& This pack contains at least two of each colour with various sizes. Colours are Red. Black. Blue. Green. I ELECTRONIC& Yellow and White. Pack of 20. 10+ $5.50 I ELECTRONIC& I ELECTRONIC& ! ELECTRONIC& I ELECTRONIC& I ELECTRONIC& This unit will store telephone numbers as well as being a pocket calculator. I ELECTRONICS. The databank has 2k of memory which is 1.938 characters which will I ELECTRONICS. I ELECTRONICS. accommodate more than I ELECTRONICS. 100 names and telephone Colours are Green. I ELECTRONICS. numbers. It measures 58 x57 I ELECTRONICS. x 4mm thick. It has a special I ELECTRONICS. security code to protect private I ELECTRONICS. numbers! Other features include I ELECTRONICS. • auto power off• edit feature I ELECTRONICS. I ELECTRONICS. • 10 digit calculator I ELECTRONICS. • includes battery. I ELECTRONICS. Cat OM-7200 I ELECTRONICS. I ELECTRONICS. I ELECTRONICS. i<at>t•:•:•························································································.....···························,.,,..·.················································.....""'· I ELECTRONICS. I ELECTRONIC& : ELECTRONICS. A 12V DC bug killer. Ideal for camping. : ELECTRONICS. : ELECTRONICS. <at> • boating or anywhere where there is a : ELECTRONICS. 12V DC supply and insects. Comes with : ELECTRONICS. a 2 metre lead and cigarette lighter plug. ' ELECTRONICS. Insects are attracted to the light and are We are all becoming aware that lightning in storms and voltage spikes can severely damage sensitive · ELECTRONICS. electrocuted when they crawl over the ' ELECTRON ICS. electronic equipment that is connected to a phone line. i.e.. fax machines. answering machines. modems. etc. metal contacts. An inverter increases ELECTRONICS. the 12V to a high voltage. The contacts ELECTRONICS. The best way to help prevent these harsh spikes is by installing a Jaycar Fax - Phone Modem Line Protector ELECTRONICS. are well out of the reach of small between the Telecom line and your expensive equipment. The big problem with such a filter is that owing to ELECTRONICS. probing fingers. Save$$$$ over 240V the magnitude of t~e voltage spike no practical filter could be guaranteed to catch rNery spike rNery time. ELECTRONICS. models. ELECTRONICS. Cat. YS-5520 We cannot guarantee that this filter will solve 100% of lightning induced telephone ELECTRONICS. ELECTRONIC& line spikes destroying your equipment. We can say however. that this device ELECTRONICS. will give your equipment a reasonable chance of survival in a storm. ELECTRONIC& ELECTRONIC& We are offering you a one month trial on this product. If you are not satisfied SURPLUS STOCK INTO CASH!! ELECTRONICS. Jaycar will purchase your surplus stocks of components and with its performance return it in original condition along ELECTRONICS. equipment. We are continually on the lookout for sources of prime with your receipt for a full refund ELECTRONIC& __ q~l~_merchandise. less post and packing. ELECTRONICS. CALL MARK HAKRIS OR BRUCE ROUTLEY ELECTRONICS. Cat. XF-7000 NOW ON (02) 747 2022 ELECTRONICS. ELECTRONICS. ELECTRONICS. ELECTRONICS. ' ELECTRONIC& ELECTRONICS. ELECTRONICS. ' ELECTRONICS. • ELECTRONICS. brand. · ELECTRONICS. ~: i~;~}~;r~~;~~~tro separate windings !· ' ELECTRONICS. Similar to the conventional hand-held units. The readout is in the body of the . : ELECTRONICS. :::: 1.2 NH c$1cIty ' ELECTRONICS. probe. Logic probe bonus. This TTL/CMOS unit will test Logic HI and Logic LO. • Circuit protected to 250V. All electrical symbols are shown in the large 42mm x ' ELECTRONICS. ; ' ELECTRONICS. · ' ELECTRONICS. j 10-wi"dM. :~::;: ' ELECTRONICS : ELECTRONICS. : ELECTRONICS : ELECTRONICS : ELECTRONICS : ELECTRONICS\ : ELECTRONICS,! : ELECTRONICS ' ELECTRONICS · ::AR E.LEC"IHONI '.:AR ELECTRONICSJAYCAR ELECTRONICS JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELEC TRONICSJAYCAR ELECTRO '.:AR ELECTRONICSJAVCAR ELECTRONICS JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRO '.:AR ELECTRONICSJA YCAR ELECTRONICS JAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRO '.:AR ELECTRONICSJA YCAR ELECTRONICS JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRO :;AR ELECTRONICSJAYCAR ELECTRONICS JAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRO . ,,y· OLAR POWERED CALCULATOR , !iit' I EUROPEAN STYLE 101 KEY KEYBOARD !!! :!! I a Our price ~99 $24.95 ~, •~~~~ ♦ :~ :_ .: ,l .?:?ii57ffcj ~. . . . . . . . .. . ... .......... ~ R~i~ ¾------ii Alligator clip pack All this for $5.00 $6~95eaea 0 0 , Personal Databank/Calculator ~ l:~~~:~""·•---™·-,-j ::W'.· i=ax-Phone Modem Line Protector ii • Protect your expensive telephone equipment etc. from I !: storm damage • Transparent to normal communications Uses no power ...,\l $34.95 :«~:!!~ {tauG KILLER \ l l $29.95 TURNYOUR $99.00 !lit'. RANSFORMER j MADNESS!! ,:,: NOW ONLY .:.: . $1 99 ea I ""t''·· robe Type Digital Multimeter : 31/2 Digits. Manual ·or Auto Range with Logic Probe - Only 6.50 :~,1~ 5 ~ C::~ . '~' and 'D' size N1Cads so cheap? ~c~ty;iu;; $59~95 ~i~~:... mw •• , - -- - •• · - · ~ · - - - ...,, , , ..... " , ............. , , ..... , •• >J'-ioJ',, . . , , " , ,_.._,_.., , , , . . , , . , . . , ..,..,, ' ' .... , ", ........... . . , ' ' , . . , , .. ,..,>JOJ, , . ...., ... \ ........... .., !!~;;'-·· W Pro Series Power Amp Kit :!:! f :f: (~ Ref: EA December 1988 14rNv rms per channel. 0.007% distortion at full power. Full kit Cat KA-1725 I $599 i :~ ·,_:._:·_j i>STUDIO 200 HI FI PREAMP Ref: Silicon Chip June. July 1988 High quality, reasonably priced Hi R stereo preamp is presented here. Ideal for home or road wo it can be matched with any power amp with a standard input sensitivity of 1V rms. It is housed in 44mm black rack case and requires 240 volts AC. See catalogue for full details. • Cat. KC-5033 $229 CONCORD VISA i HURSTVILLE r r ,...,,,, ,..,vvr'\ ,....,,....,\,_._._....,,I,.....,, ,,,....,~ ,...., Ur\11 ,_ ,_._..., 111'-'1 \II I U ~ r \ , unn LL.L V I n v, ... , ....,~..,r\ l VMn C LCV I n The Bose Lifestyle Music System Last month we previewed the new Bose system and we promised to tell you more about it this month. Having lived with it for about 5 weeks now, we are convinced that our first impressions were right - that it could be the end of conventional hifi systems, as we presently know them. By LEO SIMPSON Let's say at the outset that not everybody will like the new Bose system. Diehard hifi enthusiasts who have traditionally liked to mix and match their own systems, upgrading the system when new products were introduced and constantly "tweaking" the system to improve the performance - won't like it. It presents too much of an "end solution" to the problem of hifi sound. 38 SILICON CHIP Nor will those people who revel in the complexity of conventional hifi like the Bose system. It has no rows of knobs and dials to impress or confuse - it ain't a knobtwiddler's delight, that's for certain. Nor will the "high end" hifi purists like the Bose, for reasons that will become clear as we go along. But the great majority of people who like good music and the good sound that comes from conventional hifi will love the concept of the Bose Lifestyle Music System at least, that's what we think. Technical features Now let's have a closer look at the Bose System, starting with the compact unit which Bose refer to as the Music Centre. Finished in satin aluminium, it measures 420mm wide, 65mm high and 245mm from front to back. It combines a compact disc player and an AM/FM stereo tuner, along with switching for external program sources. There is a window on top of the unit which shows the source selected, the zone (1 or 2) and the station frequency, when the tuner is in use. In the same cutout of the lid are 7 pushbuttons which can be used to control some of the unit's functions ◄ Pictured at left are the normally visible components of the new Bose Lifestyle Music System. Not shown is the powered Acoustimass loudspeaker which provides the low bass output. but as we said last month, this is really best done from the remote control handpiece. Pushing a latch at the front of the case releases the lid so that it gently opens to reveal the ''well'' for the CD player. There is no fancy motorised disc drawer; it is simplicity itself. You just place the compact disc into tµe well, close the lid and the machine does the rest, by remote control. Also concealed by the lid are 7 buttons which are used for programming the AM/FM tuner and for selecting external program sources. Up to 30 stations can be programmed into memory and they can be any combination of AM or FM stations. Stations can be programmed in several times so that more than one person can have a preferred list, which can be pencilled into a panel on the back of the remote control handpiece. At the rear of the unit are two rows of RCA sockets, for a tape monitor loop (same as in any hifi system), for connection of two external line sources (such as a hifi video recorder and perhaps another tape deck), and for two pairs of stereo outputs, for zone 1 and for zone 2. Also on the back panel are the power switch, two screw terminals for connection of a loop antenna for the AM receiver and a 75 ohm coax socket for the FM antenna connection. Finally, there is a 3.5mm socket labelled "serial data output" which we'll explain later. On the righthand side of the unit are two 3.5mm stereo sockets. One is for connection of a W alkman style cassette player while the other is for connection of stereo headphones. If stereo headphones are plugged in, they mute the main amplifier and loudspeakers. Heard but not usually seen, the powe_red Acoustimass has a large heatsink on one side to provide cooling for the transistors in the power amplifiers. Also visible are the two ports which tune the enclosure and the bass and treble controls (near the lower port). Single microprocessor While we did not pull the Music Centre apart, it is evident that there are a number of clever things going on inside. For a start, there appears to be only one microprocessor instead of the two that would normally be used for a synthesised AM/FM stereo tuner and for a compact disc player. Secondly, the tuner and CD player must have been very carefully designed so that they don't interfere with each other. Remember that contrary to most hifi systems, it is possible to use both the CD player and the tuner simultaneously. Normally, CD players radiate a significant amount of radio "hash" which can cause reception problems for a tuner (particularly on AM) in the near vicinity. Not only that, but crosstalk between the two internal sources (and external sources) is very low. That has to the case otherwise someone listening to CDs would hear a radio station in the background when the tuner was selected for the other zone. Try this test with headphones and with the volume wound up on a conventional hifi system with a separate tuner - you'll see what I mean. A hidden feature is the remote control receiver and decoder circuitry. Why do we say it is hidden? Well it operates at 27MHz and yet has no apparent antenna - this function is performed by the shield of the audio output cables to the powered loudspeaker. The compact disc player itself is a fairly conventional unit, with dual 16-bit digital to analog converters, two times oversampling (88.2kHz), and digital and Bessel analog filtering. Remote control We're not going to list all the functions of the remote control handpiece - they were covered pretty well last month. A few points should be made though. One very worthwhile feature is that when the I A closer encounter with ·a radical new hifi system I OCT0BER1990 39 Powered Acoustimass These are the twiddlers which handle virtually the whole audio spectrum down to just below 200Hz. Note the tiny size of the drivers with their plastic domes and miniature foam roll surrounds. Just how do they work so well over such a wide frequency range? system is first turned on and starts to play, the volume setting is fixed at - 40dB below maximum output - quite a modest level. This is a good idea and much better than having the system come on at the level at which it was last used. If that happened at night ·(as it can with conventional systems), it could wake everybody in the household. Security coding One of the potential problems with an RF control such as this is that there could be interference, because the unit has quite a long range - 20 metres at least. It is easy enough to imagine this situation where two neighbours, either in a block of home units or two houses close together, both have Bose Music Systems. Could one owner control his neighbour's system - inadvertently or otherwise? 40 SILICON CHIP The answer is yes but Bose have already thought of this situation and have the solution. Inside the battery compartment is a 4-way DIP switch (four tiny slide switches close together). Three of these switches set a security code for the remote control so that if you have an interference problem you can change the security coding. A similar DIP switch on the underside of the Music System needs to be set to match the remote control. Those three switches (out of four) give 8 possible codes - not many, but probably enough The fourth switch is there to set the volume mode for listening zone 2. The normal factory setting makes the signal level adjustable by the remote control in the normal way. The alternative setting makes the signal level fixed - to suit the situation where Bose powered Music Monitors are used. These have their own volume controls. As indicated in last month's preview, the loudspeakers are a powered version of the Bose Acoustimass 5 - a satellite cum superwoofer system. The Acoustimass is a pretty radical system in itself and quite unlike conventional loudspeaker systems. The superwoofer is perhaps the· most unconventional part. It measures 464mm wide, 321mm high and 250mm deep. Inside, there is a partition dividing the enclosure into two compartments and also carrying two 15cm (6-inch) drivers connected in parallel. Each compartment is vented by a tuned port. In effect, the Acoustimass enclosure is a double-tuned resonant system with the two resonances about an octave apart (actually around 55Hz and 130Hz). The system is then equalised electronically to cover a range of about two octaves. The two system resonances actually create a tuned bandpass system. This effectively stops the system from producing much output below about 45Hz (just like any conventional tuned system) but it also has a beneficial effect in attenuating any harmonics above about 200Hz. Thus, even if the bass drivers produce quite significant distortion, it is effectively filtered out by the physical bandpass system of the tuned ports. No other system around has any such system of distortion filtering. This filtering effect has two very interesting effects, which we'll come to later. This powered version of the Acoustimass 5 dispenses with some of the passive overload protection of the previous model and does it electronically instead. Most people, when they see the powered Acoustimass system for the first time, don't twig to the fact that it is a speaker, or an amplifier for that matter. The clue that it is an amplifier comes when you look at one side and see that more than half of it is a black anodised aluminium heatsink. The other clues are that it has a power cord and signal lead, and two pairs of speaker terminals for powering the satellite "twiddler" speakers. Mounted on the steel backplate of the powered Acoustimass is this large printed circuit board which carries the three class-G power amplifiers and all the associated small signal circuitry for electronic crossovers, automatic loudness compensation and overload protection. At one end of the box are the two ports mentioned earlier and the bass and treble controls which are intended mainly as presets - you set them at installation and then forget them. Internal electronics We took the liberty (curiosity got the better of us) and had a look inside the Acoustimass system to see what made it tick. As you can see from the photos, there is not much to the speaker enclosure but the electronics is another matter entirely. Again, it is very cleverly thought out. As can be seen, all the electronics is laid out on a large printed circuit board which accommodates a 100 watt amplifier to drive the internal woofer system and two 50 watt amplifiers to drive the satellite "twiddlers". Notice that the power transformer, propped up on a compliant suspension system, and the filter capacitors, are not very big. Yet the whole system is rated at 200 watts total. It delivers it too and a little more besides, as we shall see. Our first surprise came when we realised that the woofer impedance was around 4 ohms and not 8 ohms as in a conventional hifi speaker. But then again, why not. After all, since it is a powered speaker, speaker lead resistance is not a problem (they're only about 20cm long!). Designing for a 40 load means that the supply voltages can be lower, and so the overall power dissipation is lower. Going into it a little deeper, there is little need to derate the output transistors for second breakdown effects and long term reliability should be better. The twiddler speakers are a nominal 80 and so their 50 watt amplifiers are more conventional, at least in terms of their intended load. But there is more to come. Class G amplifiers All three power amplifiers operate in class G. This may be a puzzle to many hifi enthusiasts but it is an amplifier configuration pioneered by Hitachi in the early 1970s. Basically, class G is a conventional class AB amplifier in which the supply rails are varied according to the amplitude of the input signal. When the signal amplitude is low, the supply rails are low and so the quiescent power dissipation in the amplifier(s) is low. When a bigger signal comes along, requiring a lot more output power, additional transistors switch the output transistors to a higher supply voltage. Thus, the amplifier can deliver a lot more power for a short period. It is an effective way of increasing the amplifier "headroom" or peak power output. Amplifiers made by Carver, NAD and Proton also effectively vary their supply rails and get a similar result - · more bang for your buck. Back to the main plot. Remember how we said that the Acoustimass system was like a tuned bandpass filter - removing harmonic distortion caused by the woofers. Well, it also effectively removes harmonics which are caused when the amplifier is badly over-driven into clipping. Normally, when an amplifier is OCTOBER 1990 41 Bose lifestyle Music System driven into clipping it is only too apparent from the dreadful noises that emanate from the speakers. But with the Acoustimass, that "safety margin" is removed and it would be possible to badly overdrive the system without the listener being readily aware of it (apart from being deafened). The Bose people admitted, at the launch of the Bose Music System in July this year, that this presented a problem. They got over this problem with their earlier unpowered Acoustimass 5 system by a pretty fancy system of protection. They told us that they had a completely different method of protection with this powered version of the Acoustimass system but they weren't saying how it worked. Signal limiting We found out how it worked by accident, when testing the system for power output. We're getting a little ahead of ourselves here but basically it works by signal compression. Once the amplifier is near the point of clipping and therefore serious overload, the compression circuitry cuts in to limit the signal from increasing any further. It is very effective. Bose has borrowed from its experience in the public address field and has incorporated a limiter which is commendably distortion free. So what we have is a trio of power amplifiers which deliver quite a lot of power in their normal mode, can deliver more on signal peaks due to class G operation, and then are prevented from being over-driven by signal limiting (or compression). The result is a system which can be driven to very loud levels without being distressed. Perhaps we should rephrase that - the result is a system which can deliver far more sound than the average listener will ever want. Electronic crossovers As well as the three power amplifiers and signal compression circuitry, the large printed board also accommodates the electronic crossovers to separate the signal 42 SILICON CHIP bands for the satellite twiddlers and the Acoustimass woofers. In addition, there is circuitry for automatic loudness compensation. Now this is a feature which is going to cause a lot of debate, especially among the hifi purists. Contrary to the loudness feature on most amplifiers, the Bose automatic loudness compensation cannot be switched out. In fact, I have argued in the past that loudness compensation on any amplifier was bad and the best point about it was being able to switch it out. One of my reasons for arguing this way was that the designer could not even guess what sort of loudspeakers the amplifier was going to be driving, let alone the size of room, the hearing acuity of the listeners and so on. But at least with the Bose system, the designers knew exactly what The System At A Glance Good points • Clever engineering • Remote control • Inbuilt overdrive protection • Nearly invisible speaker system • Simplicity of use • Sound quality Points for improvement • Noisy CD player • No provision for turntable • Switch-off 'plop'; see text. sort of speakers the amplifiers would be driving. So they could tailor the loudness compensation pretty closely to suit most circumstances - that's probably how they would argue anyway. To be frank, we're not keen on this feature. If we'd had our " rathers" we'd rather it was able to be switched out, if only to give the listener the option. Balanced inputs The audio inputs to the Acoustimass are balanced. This is desirable when the cables are very long as it greatly reduces the pickup of interference signals. However, the audio outputs from the Bose Music Centre are unbalanced (ie, as in conventional stereo preamplifiers) and are run in figure-8 shielded cable with two RCA sockets at one end and a conventional 5-pin DIN socket at the other. Just how balanced lines would help in this set-up we're not sure. (We did not have access to circuit information at the time of this review). And what other tricks does the system get up to? Well there is another and it's automatic switch off. If the circuitry does not get any audio signal for more than about 90 seconds, it switches itself off. This is another good feature which is desirable on a system like this which is just about invisible. Walk into a room and there is no way you'd know it was on, with no program playing. Without the automatic switch-off feature you might forget to switch it off for days or even weeks at a time. When the Music System is next used, the powered Acoustimass senses the presence of audio signal and switches on the amplifiers again. It's all very neat but this could have presented a problem when the CD was switched on. Compact disc players have such a small residual noise that it is not until the disc actually begins playing that the amplifiers would turn on, resulting in the first few notes being missed. To solve that problem, the Music Centre has its "serial data output", as mentioned earlier. This is an BV signal which is generated as soon as the compact disc function is selected, to "wake up" the power amplifiers. To make this automatic switchon/switch-off function possible, the Acoustimass has two power supplies, similar to a remote-controlled TV set. There is a small power supply which is always on and it controls the large power supply (which uses the big transformer) via a relay. Twiddler speakers While the powered Acoustimass system is very intriguing in its engineering features, so are the View inside the Acoustimass enclosure, showing the two parallel connected woofers and one of the tuned ports. There's not a lot to it, is there? Also visible is the small PC board for the tone controls. "twiddler" speakers. Each twiddler consists of two cubes about 90mm wide, each with a 60mm driver inside. These drivers combine the features of a tweeter and a woofer. They have a Mylar dome, a doped cone and a roll surround. They are magnetically shielded, so they can be used in close proximity to TV sets and video monitors. Note that two of these tiny speakers in each channel can handle program material in excess of 50 watts! But the most amazing thing to us is that they cover the whole frequency range down to below 200Hz, which must be well below the cone resonance of the drivers. Just how do Bose manage that? It has us stumped. There is another paradox with the Bose system and that involves the integrated circuits used in all the processing circuitry in the powered Acoustimass. The line-up involves some pretty ordinary ICs, such as 4558s (a dual op amp from Motorola) and a 3080 (a transconductance amplifier from RCA). But that hasn't stopped Bose from extracting very good performance from them. Again, it is a case of some very clever engineering. Performance Having read this far, you must be itching to know how well the system performs. We'll give you the objective results first. We tested the performance of the compact disc player, FM tuner and the Acoustimass amplifiers. We first tested the CD player. It can be summarised as having middle-of-the-road performance but with above average error correction and tracking. This means that it is very good at tracking and playing dirty or damaged discs - it will load and play some discs which other top quality players will reject as unplayable. It also has fast track access times which is important for a remote controlled player such as this. Bose rate the frequency response as being within ± 0.5dB from 5Hz to 20kHz; signal to noise ratio, 95dB; dynamic range, 90dB; harmonic distortion, 0.08 % and channel separation, 70dB (from lkHz to 20kHz). We measured the frequency response as flat, across the range from 20Hz to 2kHz, and then slightly rising in response to a slight peak of + 1.3dB at 18kHz and then - 0.2dB at 20kHz. We would guess that this slight peak is caused by the Bessel analog filtering. The signal-to-noise ratio was - 102.5dB unweighted or - 109dB A-weighted, which probably means that the player output is muted, for this test. (Most players are effectively muted for this test). However, a look at the residual distortion products indicate that the dynamic range is close to 90dB, as claimed. Harmonic distortion was generally around .05% which is better than claimed but still fairly average. Linearity was pretty average too, with an error of + ldB at - 70dB, + 3dB at - B0dB and + 8.5dB at - 90dB. For the record, the best result we have ever seen for a CD linearity test was + 0.4dB at - 80dB and ldB at - 90dB. The measured channel separation was - 91.2dB at 100Hz, - 86dB at lkHz, - 65dB at 10kHz and - 60dB at 20kHz. Control unit As a stereo control unit, the Music Centre measures quite a lot better, with frequency response flat from 20Hz to just - 0.6dB at OCT0BER1990 43 20kHz and - 3dB at 50kHz. The sensitivity is 525mV for 1V out. Distortion is generally less than .005 % while the signal to noise ratio is - 104dB unweighted and - 108dB A weighted. Separation between channels was better than - 96dB at lkHz and lower frequencies; - 82dB at lOkHz; and better than - 76dB at 20kHz. These are good figures. More important is the figure for crosstalk between the different sources, such as when the tuner is selected for Zone 1 and CD for Zone 2. We measured this for the Aux and Video inputs and achieved results of - 97dB at lkHz and - 81dB at lbkHz. This is an excellent result and far better than could be expected from a conventional stereo control unit. Of course, as we remarked previously, it has to be. FM tuner Bose's tuner specs are as follows: 50dB quieting sensitivity, mono 18dBf, stereo 38dBf; distortion at 65dBf, mono 0.15 %, stereo 0.25%; signal to noise ratio, mono 75dB, stereo 72dB; frequency response, 30Hz to 15kHz ± ldB; separation 30dB; capture ratio 1.7dB; alternate channel selectivity, 65dB; image response 95dB; AM suppresion 60dB; and subcarrier product rejection, 40dB. Unfortunately, we are not set up to test some of these specs but we were able to confirm the frequency response as better than ± ldB from 20Hz to 15kHz and the separation at lkHz as 40dB (better than claimed). We measured the signal to noise ratio at 65dB in both stereo and mono modes but the limiting factor there would be our Meguro FM generator. Amplifier performance Measuring the amplifier performance for the Powered Acoustimass system is bit of an obstacle course. You can measure the performanc e of the satellite driver amplifiers readily because their outputs are accessible. But even then you have to be aware of the equalisation and automatic loudness compensation. To measure the bass driver though, you have to gain access inside the enclosure, disconnect the woofers and connect a dummy load. Having done that, we can report that the amplifiers perform very well, as straight amplifiers. We'll clarify that in a moment. For the satellite amplifiers, we verified their power output at 50 watts per channel into 8-ohm loads for a total harmonic distortion of around .01% (dependent on the signal frequency). At lower power output, the distortion was much lower, around .005%. The frequency response was not flat (nor is it designed to be, with equalisation and so on). Interestingly, Bose appear to use an external RLC network at the amplifier outputs to roll off the high frequency response quite heavily: - 7.5dB at 20kHz. We're not sure why - they just do it. This oscilloscope waveform shows the effectiveness of the overdrive limiting circuitry. It shows the amplifier output with a + 4.6dB input overdrive. At this input level, conventional amplifiers would be clipping severely and yet the Bose amplifiers are giving a good waveform (5% harmonic distortion). 44 SILICON CHIP Also the electronic crossover has a rapid rolloff to protect the twiddlers against signal frequencies below 200Hz. The class G amplifiers give a headroom of 1.5dB, meaning that the music power output is 70 watts - quite a useful increase. For the woofer amplifier, we confirmed the power output as 100 watts into a 4-ohm load for a total harmonic distortion of around .035%. Again, at low power, the distortion reduces. You have to "step around" the equalisation and the electronic crossover here too. This prevented us from doing a headroom test on the woofer amplifier, principally because it has a severely curtailed response at lkHz, the normal headroom pulse test frequency. But we have left the best till last - the limiter circuitry. This is in circuit all the time but has no effect on the distortion at normal signal levels. The maximum level of over-drive possible before clipping was + 12dB, amounting to four times. At + 4.6dB, the distortion was 5% while at + l0dB it was 10%. While a distortion level of 5 % may seem high, it consists mainly of low order harmonics which are not anywhere as audible as even a very modest degree of clipping. What we're saying is that this is a very effective system of protection, meaning that no matter how high the level is set via the remote control, the speakers will not be over-driven. Therefore, damage to the speakers due to careless use of the volume control (via the remote) is impossible. In effect, Bose have made the system idiot proof. What a good idea. How it sounds Enough of the objective results, how did it sound. In a word, dramatic. Everyone who came and heard the system went away very impressed. People just could not believe that those tiny speakers were producing all that beautiful sound. Even when the Acoustimass woofer box was brought to their attention, they still could not believe a:: UJ We also found that on constant tone testing, there were a couple of frequencies that produced audible rattling from the Acoustimass heatsink panel. This did not become audible on music programs though. -1 0 ~ 0... 5 0... -20 ~ ~a< ~ I I -30 ~3: < (I) ~ ... I a: co -40 ~"O a:-~ UJ 0 -50 I 0... 1:J 0... 1:J 0 - J :J .- 3: ......... -60 '\ Other comments ' \ \. ' I' j 100 10 ~ \. \" 1000 FREQUENCY IN HZ Essentially, the Acoustimass enclosure is a double-tuned system which covers a frequency range of just over two octaves. This gives a bandpass effect which filters out harmonic distortion produced by the woofers. SHORT PORT FRONT Al R VOLUME LONG PORT ENCLOSURE This diagram shows the basic layout of the powered Acoustimass superwoofer system. The cabinet is divided into two compartments and carries two 15cm drivers connected in parallel. The amplifier electronics sits in one half of the cabinet & is mounted directly on the heatsink. it. And neither could we, actually. Personally, while my brain told me that all the bass was coming from the Acoustimass enclosure, my ears told me that it was coming from the twiddlers. Why is it so convincing? We put it down to the fact that the Acoustimass system produces very little harmonic distortion and that it cuts in below 200Hz. This means there is nothing to "cue" your ears, to tell you that the bass speakers are working. It is incredibly effective. More objectively, the frequency response from the twiddlers is quite smooth and extended. The bass though, we found to be too heavy, in most listening situations. In fact, we. used it with the maximum bass cut setting and even then it was a little too strong, particularly on classical music. On a negative note, we think that the CD player is a little too noisy. This is a criticism that can be aimed at quite a few CD players. They are not at all silent, unlike phono turntables which are totally quiet. Another problem we noted is that if the Music Centre is turned off using its rear power switch (or at the wall power point), it gives a loud clunk from the speakers. This situation will not occur in normal use but its something Bose should look at. And finally, how would we sum up the system? Intriguing and exciting, would be the operative words. Clearly, the Bose Lifestyle Music System is the most innovative hifi product we have seen for many years. It borrows a number of ideas which have been seen before (such as in systems made by Bang & Olufs(;ln) but the way in which all the features have been brought together is quite outstanding. The team who designed this system really have thought long and hard about what should and should not be in a hifi system aimed at the widest number of consumers. Is it really hifi? This is the question that we posed at the end of last month's preview. Of course it is. By a number of standards, such as the overload protection, it represents a big advance. But no, it is not up to the standards set by "price is no object" high end hifi components. Nor could you expect it to be. The overall performance though is to a very high standard. We predict that the Bose Lifestyle Music System will be much imitated in the years to come. There must be many hifi companies around the world wringing their hands and saying, "Why didn't we think of it?" At around $4600 for the basic system, Bose are going to be hard put to satisfy the demand. And now, enough of this. Go out and have a listen at your nearest Bose retailer. ~ OCT0BER1990 45 1-9 ..... 10+ 3 1/2"0D $19.95 $18.95 31/2"DD 31/2"HD $39.95 $37.95 31/2"HD $49.95 $47.95 $9.95 51/4"0D 51/4"DD $8.95 51/4"HD $19.95 $17.95 DYSAN 1-9 ..... VERBATIM 1-9ao,. 10+ 1-9 ..... 10+ 10+ 10+ 3 1/2"DD $22.95 $21.95 31/2"DD $29.95 $27.95 31/2"DD $32.95 $31.50 3 1/2"DD $39.95 $37.95 3 1/2"HD $39.95 $37.95 3 1/2"HD $49.95 $47.95 31/2"HD $59.95 $57.50 3 1/2"HD $69.95 $67.95 51/4"DD $19.95 $18.95 51/4"DD $19.95 $17.95 5 1/4"DD $24.95 $23.95 5 1/4"DD $19.95 $18.95 51/4"HD $31.95 $29.95 5 1/4"HD $29.95 $27.95 5 1/4"HD $32.95 $29.95 5 1/4"HD $39.95 $37.95 ALL PRICES PER PKT/BOX OF TEN r----------- f¼~ "8 PAGES PER MIJ\"UTE!" 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Fits most 6502 "compatible" computers. C14200 ................. $29.95 be X18036 ... $199 NORTON'S SI V- 4.0 3456789 X18036 IBMXT IBM PS2 MODEL 30 10MHz XT IBMAT 1----+-----------t I THE WORLD! For quality and a great price this EGA vid the cheapest m the world. Using advanced paradise chip technology, 1t reltabllity and maximum performance. ' FEATURESINCLUDE· Full compatibility with XT, AT, 3B6 Full 256K display memory Completely backward comp. with CGA, MD Hercules with intelligent switching software. 480 line extended EGA mode. I I 1 I 1 ONLV ...... $139 I I Low cost siren for burglar alarms Want a really loud siren which will wake the dead? Well, maybe this one won't wake the dead but it will certainly disturb the living. It's built on a tiny printed board that takes up hardly any space at all. By LEO SIMPSON Since it runs from 12V DC, this siren could be used in a car or home burglar alarm system. Its current requirements are fairly modest, at 1.25 amps, so it could be switched into circuit with a relay or a power transistor. It does not have any time out circuitry so that will have to be added, if required. What it does do is make a very loud sound with a minimum of components. It is a classic siren sound, heavily modulated in frequency at about a one second rate. It uses just one CMOS hex Schmitt trigger IC and six low cost transistors. The way in which these components are hooked together to produce this alarm circuit is quite interesting. First, there are two oscillator circuits. ICla is the low frequency oscillator. Its operating frequency of about lHz is set by the lMO resistor and lµF capacitor. The second oscillator is based around IClb and its basic operating frequency is set by the 2.2MO resistor and .OOlµF capacitor. It is modulated up and down in frequency by the RC network connected to the output of ICla. Its range of fre- quency modulation is from about 600Hz to 3.6kHz; ie, about 6 to 1. What happens is that ICla oscillates at about lHz and produces a square wave at its output. This is filtered to a rough sinewave by the 220kn resistor and its associated lµF capacitor. This signal is then fed to a 2.2MO resistor and clamped to 4. 7V by zener diode ZDl, after which it is fed to IClb via a .OOlµF capacitor. Thus ICla frequency modulates IClb. Hence, the output of ICl b (pin 12) is a square wave of varying frequency. Its amplitude is almost exactly equal to the input supply voltage minus the voltage drop across diode Dl. Dl is there merely to prevent damage if you connect the supply around the wrong way. The square wave output of ICl b is inverted by IClc and fed to the base of transistor Ql and to paralleled inverters ICld and ICle. These then drive the base of transistor Q2. H-pack output Just one CMOS IC and 6 low-cost transistors make up t~is nifty little siren , circuit. Don't bolt the tabs of the TIP31/32 power transistors together - you II create a short circuit if you do. 48 SILICON CHIP Four transistors, Q3, Q4, Q5 and Q6, drive the horn speaker which is what makes all the noise for this project. The four transistors are connected in an "H-pack" arrangement which effectively doubles the drive voltage fed to the horn speaker. It works in the following way. When the output of IClc goes high, it turns on Ql. Ql 's collector is connected to the base of Q4 while its emitter is connected to the base of Q5, via a 1000 resistor. So when Ql turns on, so do Q4 and Q5. The same arrangement goes for Q2. Its collector is connected to the base of Q3 while its emitter is connected to the base of Q6, via a 1000 resistor. So when Q2 turns on, so do Q3 and Q6. D1 1N5402 r 100{) +12V 1.2A 02 BC337 B 1M 2.2M + - ZD1 , J 1N7504A .,. ~ B EOc VIEWED FROM BELOW SUPER SIREN Fig.1: ICla is a lHz oscillator & this is used to frequency modulate IClb from 600Hz to 3.6kHz. IClc-lCle then produce complementary signals which drive Qt, Q2 & the H-pack output transistors. Because of the way in which the bases of Ql and Q2 are connected to complementary square wave signals (derived from inverters IClc, ICld and ICle), they turn on alternately for respective half cycles of the square wave signal. So Q4 and Q5 turn on together to pass current in one direction through the horn speaker. Then Q3 and Q6 turn on to pass current through the speaker in the opposite direction. At any one time then, the speaker has virtually the full supply voltage across it, continually being switched in one direction and then the other. This maximises the power output and therefore gives maximum scream for minimum component count. By the way, while the power in the horn speaker is maximised, the SPEAKER Fig.2: here's how to mount the parts on the PC board. Be sure to use the correct transistor type at each location. power dissipated in the four output transistors is very low since they spend their time either fully switched on (and saturated) or switched off. Either way, their power dissipation is minimal so they can be operated without any heatsink. Neat, huh? Another neat feature of this economy circuit is the use of just one current limiting resistor (1000) each for Ql and Q2. Other "Hpack" drive circuits we have seen usually use more transistors and need more current limiting resistors. Construction As we noted before, the printed board for this neat little number is teensy weensy. It measures just 32 x 45mm - about twice the size of an average postage stamp. It comes with green solder mask on the underside and a screen printed component overlay on the topside. Assembling it is hardly a major job and probably won't take much more than about 15 minutes for most people. There are a couple of points to watch though. First, the oscillator has been designed to suit Philips 40106 ICs. If you use 40106s or the equivalent 74C14s from another manufacturer, the chances are that their different hysteresis levels (ie, continued on page 69 BCIE PARTS LIST 1 PC board, 32 x 45mm, with screen-printed overlay 1 80 horn speaker Semiconductors 1 40106 (IC1 - Philips, see text) 2 BC337 NPN transistors (Q1,Q2) 2 TIP32 PNP transistors (Q3,Q4) 2 TIP31 NPN transistors (Q5,Q6) 1 1N5402 silicon diode (01) 1 1N750A 4. 7V zener diode (ZD1) Capacitors 1 4 7 µ,F 16VW PC elelectrolyic 2 1µ,F 16VW PC electrolytic 1 .001 µ,F ceramic Resistors (0 .25W, 5%) 2 2.2MO 1 1MO 1 220k0 3 1000 Where To Get The Kit Kits for this project are available from Oatley Electronics. The basic kit, containing a PC board and all parts except the horn speaker, is $10.40 plus $3.00 packing and postage. The 80 1 OW horn speaker is an extra $13.50. You can contact Oatley Electronics by phone on (02) 579 4985 or by post at PO Box 89, Oatley NSW 2223. 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And now through BULL HN INFORMATION SYSTEMS, one of Australia's largest PC service organisations, we can provide you with the ultimate in computer care FIELD SERVICE Call in and judge the quality of our computers for yourself. With 63 locations across Australia, there's sure to be a store near you. QUALITY SUPPORT HOTLINE Extensive factory testing as well as a rigourous 24 hour diagnostic benchtest by our own quality control department ensures that EVERY computer we sell has reached the highest standards of quality and reliability. for Software & Hardware Solutions (02) 888 2002 Providing 10 years of phone in Computer Support TO FIND YOUR NEAREST STORE CALL 008 226610 OR SYDNEY 888 3200 H only I'd known all the symptoms My main story this month has two levels of interest; the purely technical one - because I have never seen a fault like this before - and the human interest one involving the customer's behaviour and reaction. The story concerns a National TC-2656 63cm colour set, fitted with the M11B chassis. The owner has been a customer for many years but this was the first time that I had serviced this particular set. The symptoms were straightforward enough; according to the owner the set was dead, having failed in the middle of a program. In view of what transpired, there were probably other symptoms as well but I can hardly blame him for failing to realise their importance. Well, he was right as far as it went an:d the cause was not hard to find. A couple of fuses had gone and this led me to the horizontal output transistor, Q551 (2SD951}, which had cashed in its chips. And in the process it had taken out the regulator transistor in the power supply, Q801 (2SD850}. r---, -+-----:-"-" L - - These two devices were replaced and this was enough to get the set working. However, one of my routine replacements in this series of chassis is C555. This is a 10µF 250V electrolytic smoothing capacitor for a 190V rail derived from pin 8 of the horizontal transformer, via diode D555. This rail supplies, among other things, the RGB driver stages. This capacitor is notoriously unreliable and can fail in a variety of ways, giving rise to an equal variety of symptoms, most of them quite puzzling unless one is a wakeup. The first one I encountered was a ringing pattern on the left hand side of the picture, which led me a merry dance for awhile. By contrast, I replaced one recently as a matter of routine, which was completely dried out with almost no r-- - - · • ,-v.,....-,,""' ...J Q501 8Vp-p 20/.ISOC . Fig.1: there's not much to go wrong in this part of the MllB circuit but the job was more costly than it should have been. 52 SILICON CHIP measureable capacitance, yet it appeared to have no adverse effect on the set's performance. But I always change it anyway. Having done all that, I switched the set on and everything performed normally. I did get the impression that the picture tube might be getting a bit long in the tooth but the picture was still quite reasonable. I ran the set for various periods over the next few days and all seemed well. So I returned it to the customer. It wasn't "orright" That was fine - for about a week. Then the customer was on the phone complaining that the set was not satisfactory. Apparently it was still going but his complaint was that the picture quality was poor and, more significantly, that the picture was creeping in from the sides. I don't muck about in cases like this. Any set that bounces within weeks - or longer for that matter - is cause for concern. It doesn't really matter whether it has anything to do with the original fault or not; the customer automatically assumes it is and a deal of diplomacy - and compromise - is often needed to preserve good customer relations. So I said, "Bring it in right away; let's have a look at it". "Yeah, orright." Only it wasn't "orright". He didn't bring it in that day, or the next, and by then I was involved in other jobs and lost track of the situation. In fact, it was three weeks before I heard from him again. Then he turned up with the set and the announcement that it was dead again. The reason for the delay wasn't clear and diplomacy dictated that I shouldn't pursue it. Well, it didn't take a genius to find the trouble; the horizontal out- •• .. "ti"" uou,o.,:• II d'_--.t, ----- , ~ :: ' \ . ~ ) {_/\J ~ ,..--..._____ ·-· l'J\"( S\G 0 .. ~~-;;,--.. -. GUN \JJ~'S P-. C'RO put transistor, Q551, had gone again, but this time it hadn't taken out anything else. So a new 2SD951 put the set back into operation. But there was obviously more to it than that. The fact that the first replacement had lasted no more than a couple of weeks was suspicious enough in itself; coupled with the additional symptom about the picture shrinking horizontally, it left no doubt that there was something more serious involved. There was no immediate indication of picture shrinkage, so I found a spot for the set, near the working area, where I could keep a close watch on its behaviour. If the shrinking picture was a prelude to the transistor failure as I suspected- I wanted to be there at the first sign; these transistors are not cheap. And, to make any such change easier to observe, I fed it with a test pattern. It took several hours far anything untoward to show, and then I detected a slight inwards creep at the edges of the picture; so slight that I would have missed it on program material. I switched off immediately and moved it onto the workbench to do battle. The big gun My big gun was a CRO - a rather special type of CRO which I acquired some time ago and which quickly proved invaluable once I learned to drive it. It is a digital storage CRO and its main feature is that waveforms can be stored indefinitely, then called up as required and superimposed on a later waveform for exact comparison. More specifically, it can store up to four waveforms and any one may be compared with either another stored waveform, or an active waveform; one running "live" on the screen. Unfortunately, instruments of this type are not cheap but with today's complex circuitry, and equally complex faults, they are becoming more of a necessity than a luxury. I connected one beam of the CRO to the collector of the output transistor and the other beam to the TETIA TV TIP Philips K9 chassis Symptom: No sound. In the K9 chassis this trouble is usually a faulty IC in U240 but not in this case. We found good sound returning from the volume control but nothing at the input to the first audio amplifier. Cure: D245, a BAW62 diode near Plug P1, short-circuit. This is one of two back-to-back diodes, presumably included in the circuit to limit the input to the audio preamplifier. 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 7015. base. But by the time I had everything hooked up the set was back to normal, so I stored both waveforms. Then I let it run until the picture began to shrink again. I let this go on for as long as I dared, then stored both waveforms again. Then I brought up the previous waveforms and superimposed the current ones on them. As far as the collector patterns were concerned there was virtually no difference, but there was quite a significant difference between the two base patterns; enough to convince me that I was on the right track. Next I moved to the driver transistor, Q501 (2SC1573), and went through the same ritual. This produced the opposite result; the base pattern didn't change but the collector pattern did. So it appeared that the fault was somewhere between the base of Q501 and the base of Q551. This didn't involve much; just Q501, the driver transformer T501, and a few minor components which were quickly cleared. The best bet was Q501 and the best check was a shot of freezer. And that produced an instant cure. So out came the 2SC1573 and in went a replacement. It looked good too - for awhile. Then the fault was back exactly as before. That didn't leave much, except the transformer. But what kind of transformer fault would produce a gradual temperature fault like this? And why did freezing Q501 cure the fault? I had a feeling that I knew the answer to the second question; when I sprayed the transistor, some overspray probably reached the transformer. Fortunately, I had a spare one on hand and took only a few minutes to fit it. Reckoning up And that really did fix it. I ran the set for long periods over the next week and the pattern remained rock steady. Then I rang the owner and told him it was ready. He duly turned up to collect the set and was happy to see it working correctly. But he wasn't so happy when I presented him with another account. I had limited the charge to the OCT0BER1990 53 SERVICEMAN'S LOG -CTD ( 1989, when all these things were supposed to be in place. Not surprisingly, this has taken a good deal longer than bureaucracy had planned. And, while most of it has now been implemented, the Milton translator is still to come. In addition, the VHF channels, 4 and 5A, are still operating, the shutdown date having been extended several times. My colleague takes up the story. Colleagues's story cost of components - a little over $40 - but he obviously had imagined that there would be no further charge. So, as diplomatically as possible, I had to spell it out. The cost of the transformer was fully justified because it should have b<Jen replaced the first time around (had I been a little more astute and had he told me all the symptoms). I also pointed out that the cost of the new output transistor was also justified because had he returned the set when I asked him, it would not have been destroyed. Well, he mumbled and grumbled a bit, then finally took the set saying he would pay me later. I wasn't worried about that; he's perfectly honest but it was obvious he was taking a spot of insurance. Anyway, he came back a week later and settled the account by which time he was loud in his praise of the set. So it all ended happily. Don't you worry And now for a complete change of theme. In last month's notes, while introducing my colleague from the Illawarra area, I mentioned the change over from VHF to UHF TV in that region. It was, he said, a rather laborious process. Just how laborious became evident when we had a much longer 54 SILICON CHIP discussion. The upshot was a suggestion that he summarise the present situation and, as far as possible, predict the future. This he has done and we will get to that shortly. But first, for those not familiar with the area and its TV history, here is a brief recap of the story. The conversion to UHF is part of a broader plan to bring as many channels to country areas as are available to city dwellers. Also, in the Illawarra area, the aim is to eliminate the contentious VHF channels 4 and 5A. (Channel 4 occupies part of the established FM band, while channel 5A clashes with international satellite channels and the adjacent amateur 2-metre amateur band). The plan called for five UHF transmitters (the ABC, three commercials and SBS) at the original VHF site at Knight's Hill. To compensate for the reduced coverage at UHF, power was to be increased by a factor of 10 - from lO0kW to lO00kW (lMW), along with a taller antenna mast. In addition, three UHF translators were to be provided: one near Nowra, one near Bateman's Bay alongside VHF translators 9 and 11, and one inland from Milton. And the main VHF transmitters were due to be turned off in early At Knight's Hill, five UHF transmitters are operating - ABC, SBS, WIN, Prime, and Capital. All but WIN are on the taller mast but all with less than the planned lMW ERP - in fact, it's more like 600kW. At Cambewarra, near Nowra, four translators are operating: ABC and WIN translators with an ERP (effective radiated power) of 100W, and Capital and Prime at lkW. The ABC and WIN translators will eventually be upgraded to lkW, with the possibility of SBS at the same site. In the Bateman's Bay area, two •Wollongong Knight's1 Hin Kangaroo • •Kiama Valley:; Cambewarra • Translators OW is Mitton Translators• -a.Bateman's \ Bay • Bateman's Bay Translators Fig.2: this map shows the area from Sydney to Moruya on the NSW east coast, which is presently being converted to UHF TV. The Milton translator is yet to be built. 2kW UHF translators carrying the Capital and Prime programs have been installed alongside the VHF translators, 9 and 11, which carry the ABC and WIN programs. This mixture of VHF and UHF is to be permanent. This leaves the Milton translator still to come and this has become a major stumbling block. The planned site is about 5km west of Milton, on the edge of an escarpment some 400 metres above sea level. The plan calls for five translators, including SBS, each of 40kW. But the site is just inside the boundary of the Morton National Park, near the Little Forest trig site. This has created a conflict between the National Parks and Wildlife Service and the Department of Transport and Communications, which has been going on for nearly three years. It appears no nearer solution now than when it started. But even when - or if - the Milton translator eventuates, the overall result will be no more than a poor imitation of the coverage pro- vided on VHF. And that brings us to the main point of this discussion; by what stretch of the imagination was anyone so naive as to think that a VHF system could be replaced by a UHF system, on the simple basis of increasing the transmitter power by a factor of 10 - or any factor J or that matter. UHF signals simply do not work that way. Granted, the authorities made the gesture of prescribing a couple of extra translator sites. These will serve their immediate areas, but cannot fill in the gaps in between and there are plenty of those. Jn the meantime, the Milton translator's intended area is still dependent on the old VHF transmitters but, for WIN 4 particularly, transmission is becoming more and more precarious. This transmitter should have been replaced several years ago but has been flogged along from one postponed shutdown to another. I have monitored it on the same antenna for the past several years and it is now 12dB down on its original strength. I still get a good picture but plenty of IN ANYONE'S LANGUAGE' PROCON TECHNOLOGY LETS YOU TAKE CONTROL! We manufacture a wide range of 'real-world' digital 1/0 boards. Each board features: 8 opto-isolated inputs, 8 isolated outputs (relay or solid-state AC/DC), LED indication is provided on all I/O and IBM-PC Software is included. The system features: External mounting (up to 30 metres from computer) operating through any IBM-PC parallel printer port and capable of expanding to 240 1/0 points. Applications: Home or business security systems, process monitoring and control, laboratory automation, quality control testing, environmental control and energy management. NEW! From $199 Inc. tax PECCONtechnologg Relay ladder logic programming language a P.O. Box 655, Mt. Waverley, Vic. 3149. Tel: (03) 807 5660 Yes! High-speed drivers are provided for GWBASI C, QuickBASIC, TurboBASIC, QuickC, TurboC and TurboPascal. Our file 1/0 driver also allows many olher programs and languages to be used. E.g. DBASE, Clipper, COBOL, FORTRAN, MODUI..A-2 etc. places were only just making it at full strength. For them, - 12dB is quite intolerable. Typical of these is the Bateman's Bay area. Although this is close to the Bateman's Bay translator site, there is severe shielding between it and the extensive built-up area around Bateman's Bay township. The translators provide good coverage to the south, including Moruya, but not into Bateman's Bay. As a result, most people have relied on VHF signals from WIN and ABC which provided some service, in spite of the distance. Retired signals But a loss of 12dB is intolerable in such circumstances. A retirement village in the area, built to cater for 150 occupants, requested a quote for a distribution system for the complex. I passed the preliminaries over to an antenna installation colleague, to find out just what signals were available. He reported that UHF signals were no better than 30dBu, or around 32µV, while the VHF signals TV TEST EQUIPMENT (AUSTRALIAN MADE) SHORTED TURNS TESTER Built in meter to check EHT transformers including split diode type, yokes and drive transformers. $78.00 + $3.00 p&p HI-VOLT AGE PROBE Built-in meter reads positive or negative 0-50kV. Can also be switched to check negative voltages. For checking EHT and Focus voltages as well as TVs and _Microwaves. Hi-tension voltages. $98.00 + $5.00 p&p LOW-VOLT AGE PROBE Ideal for checking microwave ovens and TVs. The ~ ranges are from Oto 5kV and from Oto 1 OkV. Double insulated for safety. $79.00 + $5.00 p&p D DEGAUSSING WAND Strong magnetic field, larger than usual coil with multicore centre. Double insulated for safety with momentary switch operation. 240VA/C 2.2 amps. As important as having a soldering iron! $75.00 + $10.00 p&p TUNER REPAIRS We repair most tuners on an exchange basis. From only $1 7 .00 + p&p Cheque, Money Order, Bankcard or MasterCard Y.V.TuNERs) 216 Canterbury Road, Revesby, NSW 2212 Phone (02) 77 4 1154 OCTOBER 1990 55 -- were only a couple of dB better. Such levels are quite useless. A generally accepted engineering standard for colour is lmV, although 500µ V is tolerable. Below that, performance falls off rapidly, particularly at UHF where receiver front-end noise tends to be higher. So the village management was told that nothing could be done in the conventional way. The only possibility is a satellite dish to provide SBS and ABC programs. But this would make a mess of at least $3000 - probably more - just to get a signal. The cost of distribution to the 150 occupants would be over and above this and we await ,their decision. Much the same problem applies to a lot of Bateman's Bay. Another problem area is Kangaroo Valley. This is a low lying area, surrounded by hills, roughly midway between Knight's Hill and Nowra. Because it is close to Knight's Hill, it has enjoyed some VHF reception, in spite of the hills. To a degree, the same applies at UHF, with quite strong signals in many places. The snag is multiple ghosting which makes reception quite useless. The situation is so bad that local antenna installation teams will not even bother to survey the area; they advise everyone that there is no 56 SILICON CHIP ' point in trying for UHF reception. Another problem - in all areas - is the way in which UHF signals vary from day to day, depending on weather and other conditions. Signal variations of ± 6dB are quite common. As a result, antenna teams will no longer guarantee the performance of any UHF installation. They will do a field strength survey, give the best advice they can, and install the best antenna the customer can afford. After that, the customer is on his own. Shut-down date The shut-down date for the VHF transmitters is now November 1990. Before that it was November 1989, with other extensions before that. So most of us down here are adopting a believe it when it happens attitude. But one thing is certain; when it does happen, it will come as a major shock to the general public. Sure, there has been plenty of publicity and the public are supposed to be informed, but much of it hasn't penetrated. Nor has this been helped by many conflicting announcements. A typical example was a recent announcement in a Milton/Ulladulla newspaper to the effect that all the problems associated with the Milton repeater had been solved; that everything would now go ahead as planned. The only snag was that when various colleagues and myself sought confirmation from DoTC, they knew nothing about it. Nor did WIN4 or radio station 2ST, in Nowra, both of whom have a vested interest in the situation. More particularly, they need to know when the translator will come on line and when WIN4 VHF is to close WIN4 for obvious reasons and 2ST because they have an FM licence which cannot be exercised until WIN4 VHF closes. Further confusion resulted from an article in June 1990 Broadcast Engineering. It says: "After considering the results of DoTC testing ... views of residents and ... bushwalking and parks organisations, the enquiry recommended that no action be taken to acquire land in Morton National Park, until investigations have been made into an alternative system." In view of all this, the local retail and servicing industry, which bears the brunt of the public's complaints, has reason to be very concerned about the future. We know that when the VHF system shuts down, the truth will hit home hard. There are going to be large areas of population with virtually no TV service at all. And we're not looking forward to that. Granted, those people in good locations have already benefitted. They have an extra two commercial channels, five channels in all, and will continue to enjoy this service. But the price is no TV at all for many people who now have it. In summary then, it has all the hallmarks of a good idea which has become an administrative nightmare and gone very wrong. Comment Well, that's my colleague's story. My reaction is to be devoutly thankful that I work in a predominantly VHF area. I also wonder how this conversion scheme is working out in other areas since, as I understand it, it is planned as a nationwide project. Let's hope that they are faring better than the 11lawarra area. ~ FANTASTIC! SOLENOID OPERATED DOORLOCK Increases home security and garden privacy. 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ALL STOCK Videotext BRAND NEW PREMIUM QUALITY INDIVIDUALLY TESTED PCB BY THE MANUFACTURER (in our rush to get this amazing SCOOP PURCHASE to you we have not had time to check each unit so we cannot offer any warranty) "VIATEL" • Now known as "DISCOVERY" What is "DISCOVERY"? Worth well over $1 50.00 for the salvage value of the 11 bits" alone! Look at this list of component parts! • Mains Transformer - 240-9/1 5/24V 300mA • Line Isolation Transformer - Telecom approved 600/600 Ohm or 600/150 Ohm impedance. • Video/RF Modulator (Channel 0) e Low profile 12V 5A SPDT Relay e Capacitor - 2.0uF 440V AC • Crystals - 6MHz and 4.43MHz e TTL, CMOS, Linear and LSI ICs · SAA 5020, SAA 5050, 2516 and many more • Voltage regulators • Bridge rectifiers • Trim pots and capacitors• Filter capacitors • Flatpack heatsink I Plus much, rTJUCh more! Telecom "DISCOVERY" is a sophisticated information service whereby subscribers may access essential business and leisure information and transaction services. 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For component tests, a special circuit is designed, with which a single component or components in or out of actual circuit board can be easily tested, requiring no power to drive the circuit. The display shows fault of component value, characteristics of component, and haK-dead components under s nr o ot.FREE TELEPHONE EXTENSION CORD BONUS OFFER Q 0155 LABTECH DUAL TRACE CRO $799 Q 0175 2 OFF 1011 PROBE A very handy 5 metre length. KITS$ 100 USUAL TOTAL $899 THIS MONTH YOU PAY ONLY $799 This month only $7JXJ SAVE $3.00 P.0991 Normally $10.00 • Frequency Range: 200Hz-200kHz in 4 ranges Sine Wave Characterlstica: Output voltage: 5V RMS or more at no load; Distortion factor (at max output); Output impedance: 600 Ohms +/-10%; Output attenuator: 0 to greater than 50dB continuously variable;• EX1ernal Synchronlaatlon Characterlstlca; Input impedance: approx. 10kOhms; Max. allowable input voltage: 10V RMS; • Reading Accuracy 0.01%, +/-1 count; • Frequency Counter Characterlatlca; Display: 4 digits, 7mm red LED; Frequency range: 10Hz-1Mhz (square wave); Sens~ivny: 25mV RMS; Max. input: 150V p-p; Input impedance: 1MOhm; Square Wave Characteristics (TTL Out) ; Overshoot: 2% or less (at 1kHz); Rise/fall time: 200n sec or less;• Power requirements: 100/120/220V +/-10% 240V +5%, -10%, 48-66Hz Q1547 $480 PROFESSIONAL VALUE ' O • ' ! f """"- l ,ilJ ." : • ~ ''"" ,,.. ~;;.(ll , 1->J :,,. t,u f 10,. 1 • Easy to operate Simplicity itself - just select the switch to Home, Off or Away as desired. A 45 second exiVentry delay allows you to vacate and/or re·enter your premises and disarm the system. • No key switches or code buttons to push. Thus the system is idealJ or families - even the kids can operate this system. • Facilny for external siren • Battery back-up (battery S'C'cells not included) System Contents • • • • • • Master Control Unit Front Door Bell Swttch Panic/Emergency Switch Three Window/Door Reed Switches Mounting Hardware 20 Metres Wire le nstruction Manual only $129.00 NEW THIS MONTH High Performance --tll• ..... _B_LA_CK _____ RED Earth lOA/FUSE Pos. +Plugs into fuse box ~ YELL<Jw 1 - - - - - ~ Headlights BLUE Door switch circuit Doors,trunk, ,hood etc. ((r«f.<at> Re1110te control 'kev' This alarm system will be triggered by unauthorised entrance through the car doors, boot, bonnet or removal of the car sound unit. The siren will sound and the headlights flash for 60 seconds. Simple wiring, wire it yourself without professional assistance. Automatic Reset ONLY $99.00 The Protector Car Alarm (See SC Feb'88) This refined car burglar alarm has about every feature you could possibly want to keep would be thieves away. FEATURES: e Internal & External Sirens • Dash lamp flasher• Battery back up • Delayed & Non delayed inputs • Ignition killer • Easy to build and install. · :::. ;., "::: ",._ ~' '"= ,,J1 . "' ,.~ <¥p' '' , <~ :·,., +<u r t·"· , FANTASTIC VALUE Complete System S 5465 HIGH POWER CAR ALARM With Wireless Remote Control RADIO , FANTASTIC VALUE! 17 Range Digital Multimeter with Overload Protection Specification: • DC Voltage Range: 2V, 20V, 200V, 2000V IMPEDANCE; 1Mohm • AC Voltage Range: 200V, S00V IMPEDANCE: 450kOhm • DC Current Range: 200mA, 20mA, 1OA • Resistance Range: 200Ohm, 2kOhm, 20kOhm, 200kOhm, 2MOhm • Diode Test • Battery Test Range: 1.5V, 100mA 9.0V, 6mA Q 1056 Normally $49.95. This month Only $39.95 Save $10.00. MULTI FUNCTION CAR ALARM WITH WIRELESS REMOTE • •• • • K 4370 NORMALLY $129 THIS MONTH ONLY $119 SAVE $10.00 SOLDERING STATION MICRON T 2440 Electronic Temperature Controlled. Temperatur11 Selectable, Soldertng Station Now this Is really quality and vorsadlltyl The MICRON T2440 soldering station offers the ultimate in controlled temperature, hMd soldering. Simply rotate detained rotary switch freely to selectable fixed temperatures of: 320'C 1608°F), 350'C (662"F), 380'C Wireless remote activate/de-activate alarm system and central door locking system (where fitted). Horn sounds to confirm armed. light flashes to indicate disarmed. Comprehensive system protects from: (716°F). 41 0'C (770°F), 440'C (824'F) without changing heater or tip. Packed with featur11a: Temperature readout & conb"ol ;Zero voltage switching; Ground tip; low voltage element; Chrome plated, iron ctad tip • Bumping of car body eTowing • Window breaking • Forced entry of door boot or bonnet. COMPREHE T 2440 Normally $ 159.95 ave $ 20.00 Now! THIS MONTH ONLY$ 139.95 Direct Import Price! s 5225 $129.00 LCR DIGITAL MULTIMETER -- BRILLIANT AUTO RANGIN DIGITAL MUTIMETER This truly fantastic LCR Digital Multimeter enables you to test a wide variety of components. lndlspensible for the design engineer, technician and enthusiast alike. DC Voltage: Range: 200mV, 2, 20, 200, i OOOV Accuracy: 0.5% + 1 Input Impedance: 10MQ on all ranges AC Voltage: Range: 200mV, 2, 20, 200, 750V Accuracy: (50-500Hz: 0.8% + 4, 1.2% + 4(750V) Input Impedance: 10MQ on all ranges DC Current: Range: 200uA, 2mA, 20mA, 200mA, 2A. 20A Accuracy: 1% + 1(200uA - 20mA), 1.5% + • Auto-Range for Simple Operation• 3/ Digit LCD with Automatic function & Range Annuclator • Safety Design Input Jacka • Eaay, Accurate Reading SPECIACATION DC VOLTAGE Rangea: 5 (200mV, 2V, 20V, 200V, 1000V); Accuracy: +/-(0.5% rdg + 1 dgt.); Input Impedance: 100M ohm, 200mV Range, 10MOhm, the other ranges AC VOLTAGE Range■ : 4 (2V, 20V, 750V) Accuracy:+/(0. 7% rdg + 5 dgts) (45Hz to 450Hz) Input Impedance: 10M ohm DC CURRENT Rangea: 200mA, 10A Accuracy: 200mA • +/- (0.75% rdg + 1 dgt.) 10A • +/(1 .50% rdg + 5 dgts) AC CURRENT Range: 200mA, 10A Accuracy: 200mA • +/- (1% rdg + 5 dgts) 10A • +/- (2% rdg + dgts) (45Hz to 450Hz) Low Power 5 Range■ : 2k, 20k, 200k, 2m, 20M0hm. High Power 6 Range■ : 200k, 2k, 20k, 200k, 2M , 20MOhm. Continuity Buuer Translator hFE Teat 1 (200mA - 20A) AC Current: Range: 200uA, 2mA, 20mA, 200mA, 2A, 20A Accuracy: 1.2% + 4(200uA - 20mA), 2% + Q-1078 4(200mA - 20A) Resistance: 200n, 2kQ, 20kn, 200kQ, 2MQ, 20MQ, 200MQ a -1076 Carrying Case$ 12.50 a -1077 Carrying Holster$ 12.50 AMAZINGL V PRICED AT ONLY $ 119.00 Capacitance: Range:2nF,20nF,200nF,2uF, 20uF Max Input: 5V DC/Peak AC on all ranges NEW PRODUCT JUST ARRIVED! 01062 Inductance: Range: 2mH, 20mH, 200mH, 2H, 20H hFE Test: 0 - 1OOOhFE values etther NPN or PNP transistor Plus Diode test at $149.00 represents a price break through. Carry Case e a 1068 $12.50 BANKCARD Credit Card Multimeter Fantastic for the glovebox, toolkit and, of course, your top pockeL A great gift idea for the enthuaiasL Speclflcetlone: DCV: 200mV, 2V, 20V, 200V, 750V ACV: 2V, 20V, 200V; 500V OHM: 2000, 2kn, 20kn, 200kn, 2M0,20MO Includes continutty tester. Q 1060 e VISA e MASTERCARD e $65.00 PHONE TOLL FREE 008 999 007 e NEXT DAY JETSERVICE DELIVERY Country clients please allow an additional 48-72 hours M ORE AL TRONICS DEALERS WANTED If you have a Retail Shop, you could increase your income significantly by becoming an Altronics Dealer, Phone Chris Campbell (09) 328 2199 for Details. 174 Roe St. Perth W.A. 6000 008 999 007 Perth Metro (09) 328 1599 PHONE TOLL FREE ALL MAIL ORDERS P.O. Box 8350 Stirling Street Exchange Perth W.A.6000 AL TRONICS RESELLERS iii~~ ~shf;rc~:t:r~ ~r;:~sn:~r~~;~~~1!~~::::~ r,r.~~~!'s~~~r~ c:a~~\;:'~~~s:ho: 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 'I forget our ExprN1 Mall and Phone Order S.rvlce - for the coat of• local cell, Bankcard, VI•• or M•tercerd holder• can phone urder tor Hme day dNpatch. Blue Ribbon Deafere are highlighted with a ■- These Dealers generally carry a comprehensive range of Altronic products and kits or will order any required item for you. STANDARD DELIVERY & PACKING CHARGE $5.50 _to 1Kg $8 over 1 Kg AUSTRALIA WIDE - We process your order the day received and despatch via. Australia Post. Allow approx 9 days from day you post order to when you rece ive goods OVERNIGHT JETSERVICE Up to 3 Kg is $8.00- 3Kg to5Kg is $20.00-We process your order the day received and despatch via. Ovemlght Jelffrvlce Courier for delivery next day Country areas please allow additional 24-48 hours. HEAVY HEAVY SERVICE -All orders of 10Kgs or more must travel Express Road - Please allow 7 days for delivery. $12.00 to 10Kgs, $15.00 over 10Kgs. INSURANCE - As with virtually every other Australian supplier, we send 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 6pm Eastern Standard Time. Remember with our Overnight Jetnrvlce we deliver next day. WA COUNTRY ALBANY BP Electronics ■ 412681 ESPERANCE Esperance Communications 713344 GERALDTON Bird Electronics 641631 KALGOORLIE Todays Electronics ■ 212777 PORT HEADLAND Ivan Tomek Electronics 732531 WYALKATCHEM D & J Pease 811132 NT ALICE SPRINGS Farmer Electronlc1 522388 DA RW IN Ventronics 853622 ACT CANBERRA Bennett Commercial Electronics 805359 VICTORIA CITY All Electronic Components 6623506 The Electronic Component Shop ■ 6706474 SUBURBAN CHELTENHAM Talking Electronics 5842388 CROYDEN Truscott Electronics ■ 7233860 PRESTON Preston ·Electronics ■ 4840191 COUNTRY BENDIGO KC Johnson ■ 411411 SHEPPART0N Tattersal Sounds 8212892 MILDURA McWilliam Electronics 236410 WARRNAMBAL Kovoit Eiectronlcs 627417OUEENSLAND CITY Delsound P/ L 8396155 SUBURBAN CAPALABAKingsway Electronics 3902399 WOODRIDGE David Hall Electronics 8082777. COUNTRY BUNDABERG Bob Elkins Electronics 721785 GLADSTONE Supertronics 724459 MACKAY Philtronics ■ 578855 ROCKHAMPTONAccess Electronics (East St.) 22 -1 058 TOOWO0MBA Hunts Electronics ■ 329677 TOWNSVILLE Sol ex ■ 7724466 MAROOCHYDOR£Mals Electronics 436119 SA CITY Force Electronic ■ 2125505 SUBURBAN BRIGHTON Force Electronics ■ 3770512 CHRISTIES BEACH Force Electronics ■ 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 NSW CITY David Reid Electronics ■ 2671385 CARINGHAH Hicom Unitronics 5247878BLACKTOWN Sheridan Electronics 62_ 1 1494 COUNTRY COFFS HARBOUR Coifs Habour Electronics 525684GOSFORD Tomorrows Electronics 247246 GRAFTON East Coast Electronic 431250 NEWCASTLE Novocastrian . . 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. LE01-10 10% Expanded scale 11.6-12.6V voltmeter +12V0----41--+------+--+--e--.----4t----4~--411----41-....- 100% -, BATTERY Need an expanded scale voltmeter for monitoring a 12V battery'? This simple circuit uses an LM3914 IC to drive 10 LEDs in bargraph mode over the range 11.6-12.5V (ie, in l00mV steps). In fact, this voltage range is considered about optimum in order to obtain maximum battery life and avoid deep cycle abuse. Each LED can thus represent 10% of usable battery capacity and, if you like, you can think of the display as you would a car's fuel gauge (empty to full). The incoming battery voltage is decoupled by a lOµF capacitor and is then fed to the LEDs and to pin 3 of ICl. This voltage is also fed to a 10 16VW + _ R1 10k IC1 LM3914 R3 39k v,- R2 10k VR2 R4 470{l R5 470{l 500{l VR1 500{l voltage divider consisting of Rl & R2 and then fed to the input (pin 5) via R3. R4, R5 & VRl set the LED current to about lOmA, while VR2 and R6 set the voltage range (ie, VR2 sets the calibration). Be sure to keep all leads as short as practical and use a central ground point for pin 2 to stop any oscillation. When construction is complete, adjust VRl for 0.5V (Vl) between pins 4 & 6. VR2 should be adjusted so that LED 5 just lights with 6V applied to pin 5. Peter King, Airlie Beach, Qld. ($20) 0.1 47 LED1 RED 48 LED2 RED 49 51 50 LED3 LED5 LED4 YELLOW GREEN YELLOW 52 LED6 RED 53 LED7 RED 10k 470{l 22k 2200 25VW + 0.15 IC2 LM3914 IC1 LM2917 8 4.7k 0.1 VR1 10k + 10 Low-cost mains frequency indicator For some time, there has been a need for a simple device to indicate if the AC mains power supply is at the correct frequency. That's not to suggest that the frequency of the state electricity grid is open to question. Quite the contrary - it's always quite accurate. Instead, this device will be useful for checking 62 SILICON CHIP the output from petrol or diesel driven alternators through to the more sophisticated "no-break" computer and medical back-up systems. The unit will indicate small frequency deviations from 50Hz. It could also be adjusted to cover 60Hz if required. The circuit works as follows. The mains frequency is sampled at the secondary of the power transformer and fed to an 4 VR3 1k VR2 5000 LM2917 frequency to voltage converter (ICl) via a O.lµF capacitor and voltage divider network. The output voltage from ICl appears at pins 5 & 10 and is directly proportional to mains frequency. This voltage is applied to an LM3914 LED driver (IC2), which is wired to operate in dot display mode. Depending on the input voltage, it turns on one of seven LEDs to indicate the seven Obtaining - 5V from a + 5V supply Ever needed a - 5V supply when only a + 5V supply was available? This circuit will solve that problem. It's based on the National Semiconductor LM7660 switched capacitor voltage converter IC. This IC takes a positive supply and using an internal oscillator and CMOS switches, charges a capacitor at pins 2 & 4 to the + 5V rail. It then dumps this charge into another capacitor at the pin 5 output to provide the - 5V supply. The maximum output current is limited by the amount of ripple which is tolerable. At 5mA, the supply has 300mV of ripple using the 10µF capacitors shown on the circuit. The internal oscillator operates at 10kHz but this can be reduced, to minimise the current drawn by the IC, by installing a capacitor between pin 7 and ground. A 22pF capacitor sets the oscillator frequency to 5kHz. The standby current of the IC at 10kHz is 400µA. Finally, pin 6 must be tied to +5Vo-----------~+5V IC1 LM7660 5 VOUTt=-- - - o (5 3 ~X) 10 16VWi ground when the supply is less than 3.5V. Above this, the pin is left open circuit. The supply voltage must not go above 10V. John Clarke, SILICON CHIP. Digital staircase waveform generator This staircase waveform has 10 equally spaced steps, both in voltage and time. Here's how the circuit works: ICla is one half of an LM1458 dual op amp. It is connected as a squarewave generator, with its frequency set by VRl , the 4.7k0 resistor and the lOOpF capacitor. The output appears at pin 1 and is fed to the clock input (pin 14) of IC2 .----------------------+9V 10x1N914 010 20k discrete frequencies : 47Hz, 48Hz, 49Hz, 50Hz, 51Hz, 52Hz and 53Hz. The first step in setting up the unit is to adjust VRl for 3.5V on pin 5 of IC2 when the mains frequency is exactly 50Hz. This done, adjust VR2 for 0.7V between pins 4 and 6 of IC2. This means that the LEDs will change indication in 70mV steps [since the IC is capable of driving 10 LEDs, although only seven are used here). Now, adjust VR3 until the 50Hz LED illuminates. The LEDs will now illuminate progressively for the following voltages on pin 5 of IC2: 3.29, 3.36, 3.43, 3.5, 3.57, 3.64 and 3.71V, representing frequencies from 47-53Hz. Finally, if using a floating input to verify operation [eg, from a signal generator), connect a 22k0 resistor from pin 1 of the LM2917 to ground to pull the input low. Bob Rochfort, Maclean, NSW. ($30) which is a 4017 CMOS decade counter. Each output of the counter (0-9) goes high [then low again) in turn at the rising edge of each cloclc pulse. Diodes D1-D10 are used to isolate the counter outputs from each other and in turn drive pin 5 of op amp !Cl b via resistor networks. These resistor networks, along with the 10k0 resistor connected to pin 5 of !Cl b, form a series of voltage dividers. Thus, as each output goes high, a proportion of its output voltage is fed to !Cl b. This voltage proportion increases by 0.1 on each successive output; ie, the sequence is O.l(Vcc - 0.6), 0.2(Vcc - 0.6), etc. The 0.6V subtracted from Vee is the voltage across each of the diodes (D1-D10). !Cl b is the other half of the LM1458 and is wired as a unity gain buffer amplifier. The output frequency of the staircase is simply the clock frequency from ICla divided by 10. Darren Yates, French's Forest, NSW. ($20) 11 39k 14 CK 20k .,. .,. 4.7k VR1 100k 4.7k 100pf+ 65 IC2 4017B 51 4 .,. 10 37 24 47k 12 03 OCT0BER1990 63 Deals that will make our Champ 360dpi Hi-Resolution Mouse. More squeak for your dollar! CATACCM LIMITED OFFER. If you want a superb quality mouse that is fully Microsoft and Mouse Systems compatible, this is it l The Champ Mouse is a precision pointing device, suitable for all Mouse driven software, including Windows, Word , WordPerfect , Ventura, CAD packages etc. The Champ features double the resolution of lesser rodents, with 500mm/sec tracking. Software allows software $99 selection of resolution from 60 to 1080 dpi. Excellent tactile response and three button design are complemented by the FREE software that provides mouse support for a huge range of non-mouse driven programs . A MOUSE MAT and MOUSE POCKET are also included, but stocks are limited at this price so order early to avoid disappointment I 1. High performance AT/386Hard Disk/Floppy Disk Controllers Data Switches • Suits all parallel printers • 2 computers to one printer or one computer to 2 printers • 36 pin centronics connector ONLY$29.95 CAT ACDS22 • Suits all parallel printers • Crossover switch • 36 pin centronics connectors ONLY$39.95 RS-232 Break-Out The Cheapest XT Turbo Motherboard on the Planet!! This fantastic little XT motherboard has a full 8 expansion slots and uses just 5 low cost 1MB RAM chips to provide a full 640K of memory. The use of advanced ASIC chips means incredible reliability. The CPU isa state-of-the -art NEC V20 running at 4.7110MHz (switchable) with zero wait state.s . Size is just208 x 161mm - - - -- - -- - ~ DRAM Size Box 128K Bytes 256K Bytes 384K Bytes 512K Bytes 640K Bytes CAf LAAB ONLY$69.95 VGA CARD CAT VC0B0(J. NEAT Chipset PC/AT Motherboards CAT MB2861 2N If you want the performance and flexibility of a 386 machine without the pricetag, you need our new NEAT Chipset motherboard . It out-performs 16MHz 386SX systems costing much more yet offers superior flexibility. The board is superbly engineered , with top quality surface mount components for the ultimate in reliability. Features: • Rechargeable battery backup on the motherboard • Clock speeds of 12 or 16MHz (0 wait state) • Page interleaved memory uses DIL (44256, 41256, 411000) or SIP memory chips . Up to 5MB of mai.1 board memory. Can be config~ed as any combination of DOS , Extended or Expanded (EMS) memory. • Shadow RAM function System RO!vl and Video BIOS can be mapped to fast RAM for lig htning fast response • Expansion sl0ts 16 bit x 5, 8 bit x 3 • Fast - Landmark 20.5 (16MHz), 14.8 (12MHz) • Password protection in ROM • Calculator and Timer in ROM • User definable hard disk support. Drives not in the BIOS table can be entered by the user and stored m CMOS RAM. 47 disks in ROM plus·a user definable place (No 48) CAT MB2861 2N $499 (12MHz/0WS/0KRAM) CAT MB28616N 424256 x 1 424256 x 2 4242S6 x 3 424256 x 4 or 421000 x 4 424256 x 5 or 421000 x 4 + 424256 X 1 $599 (16MHz/0WS/0KRAM) PS/2 MicroChannel Memory Card Selling for a limited periodatonly: $119.00 4 Port Serial Card for UNIX. XENIX etc. CAT 102240 Adaptors ONLY $9.75 each ONLY$99 Memory CAT.DCAH ONLY $199 SAVE $26 CAT. LA9M25F 9 pm plug to 25 pin socket. CAT. LA9F25M 9 pin socket to 25 pin plug . The appropriate pins connect internally to allow for matching of senal equipment using a mixture of 9 pin and 25 pin connP-ctors (eg a 9 pm serial connector on a serial mouse to a 25 pm senal port on a PC) This is Australia's best price on a top quality EGA video card. And you get a FREE printer port (1/0 selectable) Features include: Full compatibility with XT, AT, 386 Full 256K dis play memory CAT MBXCJ CAT ACDS2 1 CAT DCAH (HDD) or CAT DCA HF (HDD & FDD) Speed up the disk performance of your AT or 386 machine by a factcr of around 2:1 with these fast caching disk controllers. 1:1 sectcr interleaving , using the latest Western Digital 1006 chip set greatly increases performance with most drives Features: • Capable of addressing hard disks with up tc 16 heads and 2408 cylinde1s . 1 or 2 drives are supported. • .Will run on a 16MHz BUS on a suitable high speed macaine, delivering a massive 200% improvement in throughput from this feature alonel • The DCAHF is available with a built-in floppy disk controller, supporting up to 2 drives which may be any mix of 360K or 1.2MB 5¼" or 720K or 1.44MB 3½" drives Lowest Price EGA card in Australia has FREE printer port! This card provides complete register level compatibility with the IBM Video Graphics Array standard (VGA). while being backwards compatible with EGA , CGA and Hercules Graphics/MDA monochrome standards. The VC1024 is fitted with an additional 256K of display memory for up to 1024 x 768 pixel resolution . Normally $349 Only $299, SAVE $50 Swts all IBM PC/XT/AT/386 and is fully compatible with XENIX. MPM or Multilink environments. Two cards can be installed in a system and the card is AST Four Port/XN hard ware and software compatible. Comes with ful l documentation . Big saving on current stock. only $175 Big savings on these fu lly IBM Compatible PS/2 memory cards Provides up to 2MB of memory (OK htted) on any PS/2 type computer. It uses 1MB DIP type DRAMs and is fully compatible with the IBM PS/2 50/60 Memory expansion option. Normally $299. Save only $249 Phone for details of other MicroChannel products lf' our Catalogue competitors burst into tears!! ........................... :rop QUALITY ELECTRONIC ■ SOLUTIONS SYSTEMS AT I LOW LOW PRICES. DON'T ■ SEffLE FOR LESS! : If you want a top quality system at a good price, check these I prices . Unlike others, all Ele ctronic Solutions systems use only I top quality components from leading suppliers. Top quality NEC I drives, surface mount technology mother boards, Japanese I keyswitches in the keyboard , etc etc. Don 't settle for less . I 80386SX/20MHz/VGA I 20MHZ/386SX system with 16 bit VGA card, I VGA monitor, 1MB RAM, 1.2MB floppy, 40MB NEC hard disk, 2 serial and 2 parallel ports and I genuine Microsoft MS-DOS 4.01. Normally selling I for $3995. Desktop Case standard, Mini Tower I case $75 extra ■ ■ only $299 80286/12MHz/20MB/EGA I Fast 12MHz zero wait state processor, with quality 20MB drive, 1.2MB floppy, 1MB RAM, 2 I serial and 1 parallel port and genuine MS-DOS 1 4.01 . Normally $2395. Desktop Case standard, I Mini Tower case $75 extra. I 1 80286116MHz I As the 80286 system above but with a faster 16MHz CPU Normally $3495. Mini Tower Case 1■ standard . only $2696 "Professional Look" =Vertical ■ Case : ■ I I I I I I I I I I I I I I I DATA COMMUNICATIONS De als OD Avtek Mod ems. Save while s tocks last! NEW! MegaModem 1234. CAT MM!234 This high performance PC/AT motherboard has everything I Others charge the same for boards with nothing' 1 This top 4uality motherboard uses state-of-the-art VLSI technology and surface mount design for best performance and reliability. Don 't accept less 1 • 12MHz zero wait-state CPU (1 5.9 MHz Landmark speed ratmg) • Up to 1MB of RAM on the mothnboard (OK fitted) 80nS or 120nS RAM can be fitted • 4 x 16 bit and 4 x 8 bit expansion slots • 2 senal and 1 parallel port built in. including cabling • Rechargeable on-board battery backup (OK RAM fitted) ONLY $499 only$199 I ~~YTEK ~ ~ CATCAESP The case comes complete with cable and specially designed ¼ size card that fits in your PC and will not conflict with your . existing hard · disk/floppy d i controller. Perfect for fitting 5¼ " or 3½ " d rives or tape backup externally. this is it Our MBXC2 comes in at a staggering 10.9 on Nortons SI - that's 31MHz compared to 4.77MHz on your standard XT. The board is fully XT compatible and runs with all standard XT cards. Speed is switchable between standard 4.77MHz and turbo speed. Up to 1MB of RAM can be fitted on-board . For even faster operation, the memory above 640K can be used as "shadow RAM " for speeding up BIOS operations or as a RAM disk The board provides software·selection of wait-state. •••••••••••••••••••••••••• 12MHzPC/ AT .. External Drive Case & Controller If you want the fastest XT on planet Earth, extra with any syst em! c AT Ms2ss12v only$249.0 The World's fastest XT Turbo 31MHz XT Motherboard cAT Msxc2 ONLY $225 I I only $3795 I so386/25MHz I As the above 80386 system but with 25MHz I CPU. Normally $5495. Mini Tower Case standard. I only$3995 I Large Tower Case $1 50 Motherboard with the lot!! • Drive bays for 3 x 5¼" FDDs or HDDs, two 3½" FDDs and one 3½ " HDD. • 4 LED indicators and Turbo switch • MHz display (2 settings to tie in with "normal" and "turbo" modes) • Heavy 1.44mm s teel construction • Dimensions: 77,i" x 16" x 15¾" CAT CAESMP This quality case .includes a 5V112V i power supply and ! has standard SCSI connectors and cable . Just fit a SCSI drive and you 're m business. ONLY $399.00 floppy, 40MB NEC hard disk, 16 bit VGA card and Monitor. Professional Style Mini Tower case. Normally $5295. Mini Tower Case standard. I Feature s include: Introductory Special I 80386/20MHz/ 2MBNGA I Fast fully 80386 system with 2MB of RAM, 1.2MB I CATCAMTP This brand new Tower case is perfect for any XT, AT or 386 machine. Superb styling and heavy duty construction make this an open and shut easel A flip down smoked perspex cover protects the d rives and power switch from accidental knocks. The power supply is a heavy duty 230W output unit Don 't settle for less I SCSI Drive Cases Internal or External, includes Software and Cable. 300/300, 1200/1200, 1200n 5 and 2400/2400 baud. only $399 Me gaModem 24 CAT MM24 300/300, 1200/1200, 2400/2400 baud . Inc. cable and Software. only $349 MBXC2 IBMXT IBM PS2 Model 30 l0MHz XT ................................. IBM AT Electronic Solutions Box 426 Gladesville 2111 Phone (02) 906 6666 Fax (02) 906 5222 We accept: Bankcard, Mastercan;l & VISA Mail orders our specialty. Freight on smaller items is now $9.00 + $2 50 P&P • All prices include sales tax • All products carry a 14 day money back guarantee (software and hard disks excepted) • All Motherboard carry a full 12 month warranty • All products carry a full 3 month warranty • All cards come with full documentation • Ring for quantity discounts and tax free prices Owing to technical advances, products we supply may in some cases vary from those pictured In all cases they are guaranteed to perform to an equal or higher standard . ................................. DC offset for digital multimeters Here's a useful accessory for your digital multimeter. Using just two ICs, it provides a precise DC offset so that you can switch your DMM to a lower scale to obtain greater resolution for monitoring voltage drift. It's also handy f ot making relative measurements. By JOHN CLARKE There are many situations where it is desirable to monitor small voltage changes rather than the absolute voltage. However, monitoring these small voltage changes can be difficult if the absolute value is high. That's because you have to switch your DMM to a high range to monitor the voltage and that in turn means low resolution. What's needed in this situation is some means of nulling out the absolute voltage reading on the DMM so that you can switch to a much lower range to obtain greater 66 SILICON CHIP resolution. And that's where this handy project comes in - it can generate an adjustable 0-ZOV voltage offset for your DMM. In use, the device is simply connected to the DMM in series with the voltage to be monitored and its output adjusted to produced a nulled reading (ie, OV). Once this has been done, you can then switch the DMM to a lower range to monitor voltage drifts over time due to temperature and load changes, etc. The idea behind the DC Offset for DMMs is hardly new. Indeed, some top of the range multimeters such as the Fluke 80 series include a relative measurement feature as standard. This allows the user to set the multimeter to read OV at any input voltage. Any subsequent reading on the display will then be the difference between the new input voltage and the preset voltage used for nulling. For example, let's .. say that our original input voltage to the Fluke 85 is 15.00V. If the relative (REL) switch is pressed, the display will then read 00.00V. If the input voltage is now increased to 16.00V, the display will only show 1.00V; ie, the change in voltage. This relative measurement feature is very useful for monitoring changes [or drift) in voltages rather than absolute voltage readings. However, it does have the disadvantage that the display resolution does not increase in the relative measurement mode. In the above example, where we measured a 1.00V change from 15.00V to 16.00V, the resolution remained at lOmV. This is where the SILICON CHIP DC Offset has an advantage, since it allows the maximum resolution of the meter to be obtained. For example, to null out a 15.00V supply, the DC Offset unit is connected with opposite polarity in series with the multimeter and the supply and adjusted so that it also supplies 15.00V. The display on the digital multimeter would then read O.OOV. The multimeter can now be reset to the millivolt range [ie, O.OOOV) which means that we can now read any voltage variations with a resolution of lmV. The output of the DC Offset unit is adjustable from 0-ZOV using a 10-turn potentiometer and, with careful adjustment, can be set to within lmV of the required voltage. The temperature coefficient of the output voltage is better than 50ppm/°C from 25-70°C, while the output impedance is a maximum of 50k0. This is suitable for the lOMO input impedance of digital multimeters. How it works Refer now to Fig.1 which shows the circuit diagram. There are two main components: an LMC7660 [ICl) switched capacitor voltage converter and a TLC431 precision voltage reference [ZDl). The v+ D1 1N4146 +16.6V T C1 4.7 25VW I I 9V ...I.. 1 - IC1 LMC7660 4.7 25VW I c1 - 2.5V A VR1 50k LIN 10T + 0·20V OUTPUT TO METER K0R DC OFFSET FOR DIGITAL MULTIMETERS Fig.1: the circuit uses an LMC7660 voltage converter IC to obtain ± 9V rails from a single 9V battery. D1, D2 & their associated capacitors step the + 9V rail up to + 16.BV and the resulting 25.BV supply is then applied to a TL431 precision voltage reference. S2 and S4 are closed. Let's see how the circuit works. When Sl and S3 are closed, Cl charges to the supply voltage of V + . S1 and S3 are now opened and S2 and S4 are closed. The + side of Cl is now connected to ground and so the opposite side of Cl which is at V - connects to C2 which charges via S4. After a few cycles of this process, C2 charges to V - . In practice, an internal oscillator which nominally operates at about lOkHz is used to drive Sl and S3. This clock signal is also inverted and used to drive S2 and S4. So the pin 5 output of the LMC7660 delivers a - 9V rail and between the + 9V rail and - 9V we get 18V. To increase this voltage further, diodes Dl and DZ plus their associated capacitors are used to double the + 9V rail. Fig.3 shows how this is done. The LMC7660 is used to step-up the battery voltage by about three times and this is then applied to the TL431 which generates a precise output voltage. The reason for stepping up the voltage is so that the reference voltage can be varied all the way up to 20V while operating from a 9V battery. This is a less expensive but more convenient arrangement than using three 9V batteries in series to obtain sufficient voltage. In fact, the cost of the IC and its associated components for tripling the supply is only about that of one battery. Fig.2 shows the internal workings of the LMC7660. It contains four CMOS switches which are shown here as Sl, S2, S3 and S4. Sl and S3 operate together, while S2 and S4 operate together. When Sl and S3 are closed, S2 and S4 are open and when S1 and S3 are open, n-------+-, D1 V+ 9V I 20V VIEWED FROM BELDW = 3 51k 7.5k S2 6 + - POWER S1 = 9V ... + I S1 I I + I 53/ 0 C2r VDUT = 2V+ -(VD1+VD2) 2 5 OVDUT = -v+ = -9V + S2 t Fig.2: inside the LMC7660. S1/S3 & S2/S4 alternately open & close to charge Cl to + 9V & C2 to - 9V. 4.7I Fig.3: how the voltage doubler works. S1 & S2 alternately open & close to charge the 4. 7µF capacitor to almost twice V + . OCT0BER1990 67 first thing to note is that Sl and S2 alternately switch pin 2 of the LMC7660 between the + 9V supply and ground. Initially, when S2 is closed and Sl is open, the 1µ,F capacitor charges to the V + supply via D1. At the same time, the 4.7µ,F capacitor is charged to V + via D1 and D2. When S2 opens and St closes, the negative side of the lµ,F capacitor is pulled to the V + rail and so the positive side goes to almost twice V +, or 18V. This charges the 4.7µ,F capacitor via D2. After a few cycles, the 4. 7µ,F capacitor is charged to almost twice the V + supply. So D1, D2 and their associated capacitors behave as a voltage doubler. Actually, the voltage is slightly less than 2V + due to the voltage drops across diodes D1 and PARTS LIST 1 plastic case , 82 x 54 x 31mm 1 PC board, code SC04209901, 45 x 51 mm 1 Dynamark front panel label, 50 x 79mm 1 50k0 1 0 -turn potentiometer 1 SPOT toggle switch 1 black banana socket 1 red banana socket 1 PC-mounting 9V battery holder 1 216 9V battery 1 knob for potentiometer 4 PC stakes TO TERMINA LS a;) V W IPl Fig.4: wire up the PC board as shown here, then mount the switch & pot. on the case lid & run the wiring. Note the wire links under the battery holder. D2; ie, 18V - 1.2V = 16.8V. This is added to the - 9V r ail from pin 5 of ICl to give a total of 25.8V which is then applied to ZDl via a lkn resistor. The tkn resistor limits the current through ZDl while the 51k0 and 7.5k0 resistors set the voltage at ZDl 's cathode (K). In operation, ZDl provides a nominal 2.5V between its reference (R) and anode (A) terminals and this sets the current through the 7.5k0 resistor to 333µ,A. Since the current into the R terminal of ZD1 is 4µ,A , the total current through the 5 lkO resistor is 337 µ,A and thus the voltage across it is 17.2V. This voltage plus t h e 2.5V developed between the r eference and anode terminals gives us 19. 7V across ZDl. This in turn is applied to a 50k0 10-turn potentiometer which allows the output to be set anywhere between OV and 19.7V to give the required offset voltage. Construction Most of the parts, including the battery holder, are mounted on a small PC board coded SC 04209901. Fig.4 shows the assembly details. Install the three wire links first (these sit under the battery holder), then follow with the resistors and capacitors. Note that the capacitors are all polarised so be sure to install them the right way around. The resistors are all 1 % types check each one for value on your DMM before installing it on the board. ICl, the two diodes and ZD1 can now all be installed. Check the orientation of each component carefully before soldering its leads, then install the battery holder and secure it using screws and nuts. Semiconductors 1 LMC76601N switched capacitor voltage conve rter· (IC1) 1 TL431 CLP programmable precision reference (ZD1) 2 1 N4148 signal diodes (D1 ,D2) Capacitors 3 4 . 7 µ,F 25VW PC electrolytics 1 1 µ,F 1 6VW PC electrolytic Resistors (0.25W, 1 %) 1 51 kO 1 7.5k0 1 1 kO Miscellaneous Tinned copper wire for links, hookup wire, solder, screws and nuts for battery holder. 68 SILICON CHIP The two output sockets are mounted near the bottom of the case to provide clearance for the PC board. The board sits upside down inside the case when the lid is screwed down & can be secured using foam rubber. The PC board'is housed in a small plastic case measuring 82 x 54 x 31mm. As shown in the photographs, the voltage adjust potentiometer (VRl) and the on/off switch are mounted on the lid, while the output banana terminals are mounted on one side. To install the hardware in the case, first drill the holes in the lid using the front panel artwork as a guide, then drill holes in the side for the output sockets. These sockets should be 19.5mm apart and should sit as close to the bottom of the case as possible. This done, attach the front panel artwork, install the potentiometer and switch, and complete the wiring as shown in Fig.4. When installing the wiring, sit the PC board on the back of the lid next to the switch and pot as shown in the wiring diagram. The PC board is then installed upside down in the case when the lid is screwed down and can be held in position using a small piece of foam rubber. Testing is straightforward - just connect the output to your DMM, switch on and check that the output voltage can be varied from 0-ZOV using the 10-turn pot. If you strike trouble, check for 25.8V between the cathode of DZ and pin 5 of ICl. This will tell you whether the fault lies around ZDl or around ICl and the voltage doubler. ~ Burglar Alarm Siren upper and low threshold voltages) will result in the oscillator frequencies being different - you may have to change some resistor values. Second, watch the component polarities, both for the electrolytic capa citors and the semiconductors, particularly the TIP31s and TIP32s. It is all too easy to put these in the wrong way around and then you have a very dud project. Testing Don't be an idiot when you hook this up to your power supply. At the very least, put the horn speaker face down on your workbench when testing it - it is extremely loud and it will just about blow your F• • iI LL LL 0 NI 0 I- en => -, C <( UHF REMOTE CONTROL EA April 89 Our latest UHF transmitter • proven reliable unit • Complete Tx kit and PCB with components for Rx kit. Tx Battery included . UNBEATABLE PRICE $49.90 for the pair EXTRA Tx $17 .20 Because of demand we will hold th is price until December 1990 XTAL LOCKED ULTRASONIC MOVEMENT DETECTOR ALARM SC July 1989. No false triggers with this proven commercial unit. supplied in kit form. Easil y con nected as a self-standing alarm, with bonnet and boot protection. Instructions provided . Gan be activated by a hidden switch or you can use it with our UHF remote control. Complete PCB and components kit, and th e prewi red transducers. ONLY $29.90 INCREDIBLE PRICE DON'T YOU MISS OUT 'POWERHOUSE BARGAIN' NEW INDUSTRIAL GRADE, 6.5 Ah seal ed Gel battery. Only a fraction of their real value. ONLY (10+ $27 .90 $24 .90) Dimensions 150 x 95 x 65 mm. We ight 2.54kg. INQUIRE about our reasonable shipping cost. Fig.5: these are the full-size artworks for the front panel & the PCB. ctd from page 49 head off if you cop the full blast. Better still, do your initial testing with a fair sized resistor connected in series with the speaker. For example, we used an 8200 5 watt resistor when we tested the unit on the bench. However, any value from a few hundred ohms up to say, 2k0 will do the job and protect your ears. What a bout different supply voltages? Yes, you can increase the supply up to 15V which is the limit for the 40106. And the circuit will operate, with reduced power, down to about 9 or 10 volts. Below that, it's not worth bothering and you would have to change resistor values to make the oscillators work correctly. ~ MASTER SLAVE SWITCH EA JANUARY 1990 Remotely switch your non remote TV off an d on via your remote controlled VCR, many oth er uses etc . One switch operation, mains filter and overvoltage protection incl uded .Gom_plete PCB an d all on board components. ONLY $24.90 HALF THE PRICE OF MOST MAINS FIL TEAS . HE-NE LASER WITH DC POWER SUPPLY This is not a kit , complete unit includes laser head with a beam sh utter and instruct ions. Ideal for leveling sights, special effects or scientific experiments ate.Power 0.7 to 0.95mW maximum. DC _Power re ~l.rem_eQ_t_s,_1 0-14V <at>_ 1A O N LY $309.00 We also have laser (mains and battery operated) kits, laser tubes, laser diodes and night viewer kits still available. OATLEY ELECTRONICS PO BOX 89, OATLEY, NSW 2223 Telephone: (02) 579 4985 Fax No: (02) 570 791 0 Certified p&p $4-$6Aust. 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The overriding reason for its popularity, apart from the 72 SILICON CHIP fact that it has proven to be a reliable design, is that it included a lot of operating features, enabling anyone to stage a small-scale light show. As well as being able to use your stereo system to control four chan- nels of lights, it could also be used as a chaser, with or without modulation by the music. We won 't dwell on all the features of the Discolight here - if you want to read the articles in full, we still have limited numbers of the July and August 1988 issues in stock. As with all good things though, someone can always see ways of making them better. In this case, one of our readers, Greg Suttle, came up with the idea of adding dimmer control to the Discolight. He made up a circuit and sent it into us and we liked the idea. The results appear in this article. We've taken his circuit concept, tidied it up a bit and put it all on a PC board to make it easy to build. Added features The new circuitry enables the Discolight to be used simply as a four channel dimmer or with all Discolight functions available while each channel operates from a preset brightness level. By using this latter mode to set the minimum brightness of the filaments, there is an extra benefit because the lamps will last longer. As well as the small printed board, the modifications include adding four sliders for the dimmer controls, four pushbuttons as "flash" switches, and a toggle switch to select Discolight/dimmer operation or dimmer operation only. These extra controls are mounted on a panel on the lid of the Discolight case. 1J: CJ ::::i 0 ~ c a: 0 u.. ...I 0 a: 1- z 0 (.) a: w ~ ~ c Circuitry Apart from the hardware items just mentioned, the additional circuitry comprises two quad op amps, 14 diodes and little else. All of this new circuitry operates at low voltage ( ± 12V} but note that the Triac part of the Discolight circuitry operates at full mains voltage and is therefore potentially lethal. If you intend to add these modifications, you will have to refer to the original articles on the Discolight for the full circuit details. As described on page 48 of the August 1988 issue, two mains wires can be removed from the circuit to make it safer to work on. Now let ' s look at the new circuitry. The four dimmer (slider} controls are shown as VR101, VR102, VR103 and VR104. They are each connected to the + 12V rail via a 200k0 trimpot. The " cold" end of each slider pot connects to a 1.2V voltage reference provided by two .;,-. ...... ~s..,,..,.+-.➔.:"4 Fig.1: the circuit uses two quad op amps. The voltage on the wiper of each slider control (VRlOl-104) is · buffered by a voltage follower (ICla-d) and fed to a comparator stage (IC2a-2d) where it is compared with a ramp voltage from the Discolight circuit. The comparators then drive the Triac stages. OCT0BER1990 73 / 79;!1~u~~~!uT 6 TRANSFORMER I 1 1 VR101 VR102 VR103 PIN 14, IC4 . .--•I---. !.i;;---;il,,,;;=:-==f'-.~JI .,,,.__.,...:s..:. : NYLON SCREW PCB VR104 1 ,~, (~ <at> 113 \._~01 101 * INDICATES CHANGED WIRING, THE NEW DIMMER CIRCUITRY IS IN SERIES BETWEEN THESE WIRE NUMBERS. (SEE P45 , AUGUST 1988) LID OF CASE Fig.2: the PCB & its associated slider controls are mounted on the lid of the Discolight case. The wiring points marked with stars are connected in series with existing Discolight wiring leads. diodes, D113 and D114. Buffered sliders The wiper of each slider control is fed via a diode (D101 for channel 1, etc) to an op amp (IC101a, b, c or d) connected as a voltage follower. Since the op amp provides a high in- put impedance and a low output impedance, it "buffers" the 50kfl slider control. Following each of the buffer op amp stages is a comparator (IC102a, b ,c d) based on an LM324 quad op amp. Each comparator compares the voltage of its respec- Fig.3: this is the full-size artwork for the PC board. 74 SILICON CHIP tive buffer op amp with the ramp voltage from the Discolight circuit (from pin 14, IC4). The ramp voltage is the key to the dimmer operation and is synchronised to the 50Hz AC mains. The ramp starts at its maximum value at the beginning of each AC mains half cycle and then decays away to a low value at the end of each half cycle. The ramp voltage is connected to the inverting input of each of the four comparators . When the voltage from the slider controls is low, the output from the comparators can only go high towards the end of each AC half cycle. This means that the associated Triac (in the Discolight) will turn on late in each AC half cycle and so the lamp brightness will be low. This is just what we want. Similarly, if the slider is pushed up to its maximum setting, the output of its buffer amplifier will be high and the comparator's output will go high early in each AC half cycle. Thus, the lamp will be bright. The output of each comparator drives the front panel LED of the Discolight and thus the Triac driver of its respective channel via a series diode (D105 for channel 1, D107 for channel 2, etc). PARTS LIST 1 PC board, code SC10111902, 79 x 90mm 1 Dynamark label, 122 x 108mm 1 aluminium panel, 122 x 108mm 4 knobs to suit slider pots 4 6mm pillars for slider pots 1 SPOT toggle switch (S105) 4 momentary contact pushbutton switches (S101, 102, 103, 104) 4 68A nylon screws and 1 2 nuts 4 screws and nuts for aluminium plate 4 50k0 linear slider pots 4 200kn miniature vertical trimpots 1 solder lug 1 600mm-length 8-way rainbow cable 1 200mm-length green/yellow mains earth wire An.extra diode, D106 for channel 1, connects between the front panel LED (LED 1 for channel 1) and foe output of IC8 of the Discolight circuit. This isolates the operation of the Discolight from the dimming circuit so that the outputs of the corn- 1 180mm-length 0.5mm tinned copper wire (for on-board links) 28 PC stakes Semiconductors 1 LF34 7, TL07 4 quad JFET op amp (IC101) 1 LM324 quad bipolar op amp (IC102) 14 1N4148, 1N914 signal diodes (D101-D114) Capacitors 2 4 7µF 1 6VW PC electrolytic 4 .047µF 1 OOVW metallised polyester (greencaps) Resistors (0 .25W, 5%) 4 1MO 1 3.3k0 4 1k0 Miscellaneous Solder, cable ties. parators do not attempt to drive the outputs of IC8. In effect, the diodes (D105, D106} form an OR gate so that the dimmer operation is combined with the Discolight operation. If each dimmer control is set to The leads running hack to the Discolight circuit should he hound together using cable ties to keep them away from internal mains wiring. Be sure to use a mains-rated green/yellow lead for the earth connection. minimum brightness, then the Discolight will operate normally. When the dimmer controls are advanced, the Discolight lamps will have a background brightness as set by the dimmers but Discolight operation will otherwise be normal. Toggle switch S 105 allows Discolight/dimmer operation or dimming alone. When S 105 is set to position 1, the Discolight is set to normal operation since the INHibit input of IC7 is connected to the wiper of switch S4a. When S 105 is set to position 2, the INH input of IC7 is tied to the + 12V rail and thus IC7 is prevented from operating and all its outputs are held low. IC8 therefore provides no Discolight functions. Flash switches Asssociated with each slider control is a pushbutton which functions as a "flash" switch. When you push the button it overrides the slider control and the lamp goes to full OCT0BER1990 75 r- 0 I I ffio C er ·~I er --' LL LL 0 :il: > 0 LL LL >< er ...J I z 0 a: w :il: :il: 0 c C!J (.) • !{l :::.'1 :::-i- l i M1~ ~ I >< er • I 0 C'-1 C'-1 a: w :c en C er LL 0 er ...J LL 0 I LL LL (') (') a: 0 Cw :c Cl) er 0 er ...J LL LL 0 :il: C ~I~:=: : I I LL LL :il: I- ::i 0 I >< er 0 :c I I >< er :il: I LL LL 0 -:f' -:f' a: :c er LL LL • ~o ~, 0 Fig.4: this full-size artwork can be used to mark out the front panel. brilliance. As soon as you take your finger off the button, normal dimmer operation resumes. Consider, for example, switch S101. This bypasses diode DlOl and feeds pin 12 of ICla directly, so that full lamp brilliance is obtained. Power for the added circuitry is taken from the regulated ± 12V supply rails in the Discolight. Construction While the additonal circuitry for the dimmer function is fairly simple, as just described, adding it to the Discolight is a bit fiddly. The most straightforward part is assembling the PC board. This done, you need to cut slots for the sliders in the top of the Discolight case, make up a control panel and then wire it all up. Before assembling any components onto the new board, carefully check it out for any faults such as shorted or open copper tracks or undrilled holes. Fix these 76 SILICON CHIP before you go any further. 28 PC stakes are required on the board. Put these in first and then the low profile components such as the ICs, diodes, links and resistors. Make sure that each IC and diode is oriented correctly as shown on the overlay diagram. Next, install the electrolytic capacitors, making sure that they go in the right way around. Finally, the trimpots can be mounted. Metalwork The next part of construction is the metalwork for the dimmer control panel. We made ours from a sheet of 1mm thick aluminium. The front panel artwork shows all the needed dimensions, as well as the holes and slots. The slots required for the sliders are best made by drilling rows of holes and finishing to size using needlepoint files. Once the panel is complete the Dynamark label can be secured and the holes cut out with a sharp utility knife. With the panel done, it needs to be mounted on the lid of the Discolight case. Again, use the panel as a template to drill holes. A large cutout can be made to accommodate the sliders, rather than cutting separate slots and so on . The panel should be located on the case top so that the sliders line up with their respective LEDs on the front panel. The dimmer board is then located next to the sliders, as shown in the photos. The PC board is supported on nylon screws and secured by brass or nylon nuts. We have specified nylon screws here because we don't want exposed screws on top of the case which need to be separately earthed. The dimmer control panel, for its part, is earthed back to the mains earth, as shown in the wiring diagram. Why the emphasis on earthing exposed screws, etc? It is to avoid the possibility of any metalwork becoming live to mains if one of the internal mains wires comes adrift. The four sliders are mounted on 6mm pillars. Mount these first, then install the four pushbuttons and the toggle switch. Now for the wiring. To keep this as neat as possible, use miniature rainbow cable between the dimmer board and sliders and between the dimmer board to the Discolight board. Panel wiring To make the wiring connections to the Discolight, you will need to follow the original wiring diagram as published in the August 1988 issue of SILICON CHIP. In order to wire to the front panel channel LEDs, you first have to disconnect the exisiting anode lead to each LED. You then connect the new wiring between the anodes of the LED and the four wires from IC8. Similarly, switch S105 is connected in series with the wire to the PC stake near pin 8 of IC9. Connect the pole of S105 to the PC stake and the other two wires from the switch as shown in the circuit and wiring diagrams. The ramp signal wire attaches directly to pin 14 of IC4. Just solder the mains wmng, either at the power switch or at the rear of the case. When complete, check your wiring thoroughly. Testing To ensure safety, nylon screws are used to mount the PC board on the lid of the case. Don't use metal screws - they could become live if one of the internal mains wires comes adrift. it directly to the IC pin. Similarly, the + 12V and - 12V supplies are obtained from the output pins of the 7805 and 7905 regulators respectively. Connect the 0V (GND) wire to the PC stake marked "6" on the Discolight wiring diagram. Finally, there must be a mains earth connection from the dimmer control panel on the ca se lid to the Discolight earth on the rear panel. Use the correct green/yellow mains earth wire for this and solder each end to the solder lugs on the dimmer control panel and rear panel of the Discolight. Use cable ties to secure all the wires tidily together. Tie them so that when the lid of the case is fixed in position, they do not come near Initial testing can be done without mains lights. All operations can checked by observing the front panel LEDs. Put the lid on the case and then power up the unit. Check that the LEDs can be lit by moving the slider controls for each channel up and down. Check that all Discolight functions are disabled when the toggle switch is set to the Dimmer position. Similarly, check that Discolight and dimmer functions can be run together when the toggle switch is set the other way. For a full test, connect lights to the Discolight power outlets. Now test that the slider controls effectively control the lamps from full brightness to off. Trimpots VR101, VR102, VR103 and VR104 can be adjusted to give maximum lamp brightness at maximum slider setting. ~ Check your wiring carefully before switching on to test the circuit. Take care - the wiring adjacent to the rear panel and the power switch is at mains potential. OCT0BER1990 77 ~i - • --- - · · · - • · · - - - • · • - • •• • - - - - •• , _. ,., ..,.,,_, •• ..., , " ' .._ .._.._ .., , , , .., , . , v'"""", 1 v r . 1 1 L..L..L...._, 1 1 \ VI .. IV ~ :LECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS 'LECTRONICSJAYCAR ELECTRONIC5JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICl' :LECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRON[CSJAYCAR ELECTRONICSJAYCAR ELECTRONJCSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELE TRONICSJAYCAR ELECTRONIC~ ICf: 1 ■5:/:!/.t:;~(:§,'t \i,!MRtEiw.t,,w~t':i:i:if::i:i/:N·w~*il:i:1<at>M~.'::.':!i.:'sAl1):=:=:i't"i''o)~<at><at>il<at>,:!/:iMN7l E l:!(: ~Iii III.I :TRONICS 1 1 ~TRIO!N;jllCiS i,\,\,t,\,!, :g~:g! il~i! :g~:g~ {'. Ejl TRONIC TRONIC TRONIC moN1cs 1-- :·•:•: ::'.:: m I ~~: v~;i~t~~r:~~=a~b~~!~ :::i=. I r~~l~~!~!ii:t~iI~o;;tiJE~E~}\~~:~gf#]~~BJ~E§l~~: 10 ,i i.l,!,i,i,: You will still need to pay the VIATEL service fee of course!! . Each videotex terminal contains a fully Telecom approved modem and all electronics to decode VIATEL signals and display them on your TV or RGB monitor. We have roughly the same quantities of 4 fairly similar models. il~il =J •••••--~~== Model #1 if Ill o, re c r,on i c s k I M • "._._rnci<:cudt.,r -.11.. .'\lit-' , ....-: ; ~:::: ;:":: n (the cheapest) ·· features full console, . " numeric keypad (for ••• entering into and operating 11alil the Videotex system). RF ·\ · out (to your TV) but no P ,\ phone._ You can plug any phone into the socket 'd d f Th prov1 e o course, e ....-'..IOliilllillllilllil phone is only used to . . access the Videotex Note: this a picture of Model #2 number anyway (some phones can be used as key pads however). This machine is all you really need. ••••= :g~:g~ : ); rnoN1cs <at>! :g~:g~ii rnoN1cs !l :g~:g~ mm :g~:g~ :{ moN1cs ■ f! TRONICS ,:::,: rnoNics :] TRONICS mm ~g~:g~ II ~ID I rnoN1cs mm :~;~;~2,!;~~::;::u:::~d;;;.38 · HURRY. HURRY. HURRY!! 1 Model #2 - identical to above but with a dedicated phone which can be used as a keypad. Cat. YV-7076 ti++M+- •~ilfll lliflfW.W $34.95 but with RF and RG output (for better quality colour on a suitable RGB it ,:;,: <at> % ~ :! I m Worth ,,,. \!:: VIATEL $34 ■ 95 Model #4 - as per model #3 but with a phone as well. Cat. YV-7078 tl !it This is one of the greatest rgains we have ever seen!! Model #3,- as per model #1 Cat. YV-7077 Ji i i: Customers have been disappointed before when we have run out. Make sure you get in quick so that you won't be disappointed. Quantities are strictly limited but once sold, they are gone forever! rnoNics ,,,,,, ~g~:g~ !l j! Ji $39.95 NOTE! All models are brand new in cartons with instructions. They are worth far more than this for the parts alone. They contain valuable Philips SAA5020 and 5050 chips. Because we are selling these at such a ridiculously low cost warranty is only one month from receipt. If you are worried about this buy a model #1 as a spare! There are two available entries into VIATEL. They are 'Discovery 40' or 'Discovery 80' depending on the level of service you require. You only need Discovery 40 with this special offer. There is a $60 joining fee and a $15 per month subscription plus Access Charge. Once you subscribe to the service you will get a pin number which will access you into the system. For more information call 'Discovery' (Telecom trademark) on 008 033 342 ~~~~~1 i'{\,,,.,\,,:,,,,,,,',:,·•:,·,:,:,':,,,,,,,,,,,.,.,,,,,:,,,,,,,.,,,.··,,,,·,.,,,,,·,:::::::,:,:,·,,··.·,·,••,,,,,.:·:::·::,:;:,,:,:,,,,:,,,',:•:':,:,·,:· ... ·.. ........, ;.·>,:· ,:, , :,•:, ::, •,·•: : :, , , , , , , , , , , ,·, ':o':'•: :,·: .·.'-"·:•:❖N':',:,: :, , , ,:, , .,., , , , , ,., , ,., :, ;: ,:,:, :,•,','•:<:· •, ·::;',,X···s::,:•,·,',,.:"':<-·'·':'·':':i':'''•:;,,,❖•-:, :'+: ': :':':':,:, ,;:, , :,: :;:,:, , .,.,•••,·,··=:··='·':~· :;TRONIC.: :;TRONICSJAYCAR ELECTRONICS :;TRONICSJAYCAR ELECTRONICS :;TRONICSJAYCAR ELECTRONICS :;TRONICSJAYCAR ELECTRONICS :;TRONICSJAYCAR ELECTRONICS :;TRONICSJAYCAR ELECTRONICS J YC EL YC JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR JAYCAR ELECTRONICSJAYCAR ELECTRON ICSJAYCAR JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELEC IC Y ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR I A c.; A ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRO NICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR c.; ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ICS. ICS. ELECTRONIC& ELECTRONICS. ELECTRONICS. ELECTRONICS ELECTRONICS. ELECTRONICS. ;~cA~ E~Ecr~oNicsJAYCAR ELECTRoNics3'AvcAR ELECTRONICSJAYCAA ELEcmoNics:iAvcAR ELEci-i=ioNics:iAvcAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR me JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELEC .JAYCAR ELECTRONICSJAYCAR ELECTROr-\lCSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS.JAYCAR ELEC jmmmmmmmmmmmmmmmnmmmmmmmmmmmmmmmmmmmm■======••••••• ;JA/ YCAR ELEC YCAREU YCAFi.EU YCARELI YCAREL YCAR EL YCAR EL YCAR EL AYCAR EL AYCAR EL YCAR EL YCAREL YCAREL YCAR EL AYCAR EL YCAREL YCAR EL YCAREL YCAREL YCAREL AYCAREL AYCAREL YCAR El YCAREl AYCAREl YCAR El YCAREl YCAREI YCAR El AYCAREI AYCAREI AYCAREI AYCARE I AYCAREI YCARE JAYCAR E JAYCAR E JAYCARE YCARE AYCARE JAYCAR E AYCAR E AYCAR E YCAR E AYCAR E YCARE YCARE JAYCARE AYCARE JAYCAR E AYCAR E Australia's Cheapest Telephone Answering Machine The public aren't ready for this one yet! This product was launched on the Australian market last year. It was state-of-the-art, reliable and low cost It was a flop. Why? Because market feedback indicated that people did not like the 'sound' of the outgoing message. This sound was. in fact. an electronic reproduction generated from a computer chip, not quite as • warm' as an outgoing tape message. The importer knew they had a good product but did not know how to sell it to an unsophisticated public. They called Jaycar. Importers dllemma: * SALE Benefit from your sophisticated knowledge. As time goes by the public will get used to computer generated voice messages. Most overseas 'operators· (especially in the USA) are computer voices · as many of you would know. In the meantime. Jaycar bought the stock at a bargain basement price, and now we are offering it to you at a crazy price! But first, you must be hapl1( with the product at any price. Quite frankly, we think that there is nothing wrong with the reproduction sound of this machine. r,Ne really cannot understand why it 'frightens' the public, but that's what they tell us.) We have tested the machine out and all the guys here have no problem with the sound. Prove to yourself that it's OK though. Buy one of these machines and try it for 14 days (21 days for mail order). If you are not completely satisfied with this product for any reason. send it back in original condition and we will refund your money in full (less post & packing costs). We can't be any more genuine than that! Superior features: Most of the sophisticated machines coming out today are single tape units. The public's perception lags behind this fact. This machine has other great features too:) Extended Satisfaction Guarantee. • Advanced VOX system that stops recording when Incoming caller hangs up Flashing LED that Indicates number of massages that have bean left - Answers to 2 or 4 rings Mamo record faclllty Massage save option Battaiy backup to retain your outgoing massage (batteiy not supplied) AUSTEL (Telecom) permit A89/16A/0057 12 month - yes! -12 month warranty AUTOMATIC FAX/PHONE sw1TcH )J~~~I~f~••dd~ Quantities limited! Grab one now! Cat. Yf-7010 ONLY $89.95 1 :1rs-··,.E..:EPH·c,N·E/-=Ai ·',1 ,,,~'l!!\'!!i!fiiilli1il&ii-. i.1.1 ~~~!:-:: •T•~•m•"gIDT•~~••"' ~r~;:fo,P_. itself in no time! See the Jaycar 199'.l catalogue 4 wire cord, suitable for PABX Yf iiilooOII, "" 11.111111•1111, ,,,. \ JAYCAR E ;:; · "--'""'~!:~~!~~;~_§_§~-ii~_t~i!?~:'~ ~~::,s!,:::!,a. _, '"-.. 00 ,:, filtj~mmmmmmmmmmmmmmmmmmmmmmz<at> ; ; ; ; . ; : ;socket ~ ;~~ [f GME ELECTROPHONE ] ; ~~~~:~;iandardplugto mCordless telephone <at> the Electrophone TC-300 i~ an excellent telephone. :l \.. $19.95 sub $200phones,youdon t havetolookanyfurther. ////// ~a:e:s~ry storage • Hi-Lo ringer level • Last number redial • External charging jack for '//// \ mhandset • Selectable pulse/tone switch • Security code • Low battery indicator • Paging for only : $279 ~~;;,~~:: ./ ❖••••❖:❖:•:•:•:•:•:•:•:•:•:•:•:•:•:•:•:•:• · -- 400 cAaLE :~1RE ,:::::. ,i<at>:;:,,,..,.,. •:•:•:•: ;····•·w• . /i/' cheapest on } TELEPHONE !:! :g~:~~RS"' ~fir ;~~this iiilii JAY OWN PHONE EXTENSION! :i:: ~~~~ !!/!/ facility • Hands free intercom at ::8se station • Telecom approved • 1 year warranty : ' ,••••• w•···i·l·l·· •. :fif:•· ··. . .·..........,. . . . . . . . . .·.· · · · .... · ···· · · ··· · ·······. .·.· ·. . . . ., , ;,;:;:;:,:,:,:,: •:•· ... . . . . . . ... . ..............•.. . . . . .. . . . . . .. . . ... . .... . tr MAKE UP YOUR ·-: ; :,: - We are still the If you want something better than the :•:•:•:❖:❖:❖.•:•:•:•:•:•:•:•:•:•:•:•:❖:•:•:• ' 9~metreCat.WB-1603 I I .. i'' ~ / ,{li:,:,. ..1 OOm rnll _$62.00 .... _·.......... -..........--- _·······._·.·.:_··~~:,;::,,.~.·.. ·..----·.. ·._ .... __:·. ,·_.·.::·____ :. ·-· •. ::•:n :: ·· ··.·· · .. ... ........ ll! 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JAYCAR 1 JAYCAR I ... ~~~g~: I ·'1,1,1, ~~g~= JAYCAR /:/ ~~g~= I§~ ::: ~~g~= ,,, 3~~g~= 1• ~~ ~==~ ;~~~;L~ JA YCAR ELECTRONICS JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELE JAYCAR ELECTRONICS JAYCAR ELECTRONICSJA YCAR ELECTRON\CSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELE JAYCAR ELECTRONICS JAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELE JA YCAR ELECTRONICS JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJA YCAR ELE JA YCAR ELECTRONICS JAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELE JAYCAR ELECTRONICS JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELE _,j!>.YCAR ELECTRONICS JAYCAR ELECTRONIC:~AYC:A~ ~L~C:!~<:lNIC:~AYC:A~ ~L~C:~ONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELE · - · ·· - - - · · · - · ·· · - - -- " •- .. •--~'"'""" ECTRONICSJAYCAR ELECTRONICS JAYCAR ECTRONICSJAYCAR ELECTRONICS JAYCAR ECTRONICSJAYCAR ELECTRONICS.IAYr.AR ECTRONI rRONIC& [ RONICS. :::_~~*:•·❖:•·•,•:•:❖:❖••-.•·-. CLCl- 1 MUNl<.,.:,JA Yl,AH t: Lt<.; I HUNl<.;:;.JAYGAH ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR FI FCTRONICSJAYr.AR FI ECTRONIC&JAYCAR .......................,•❖ ,-.-.•,:,:,•,:,-: ••••••••• -.:❖• ·•:❖:-.·❖,-.-. • •❖:❖•.v.•.•,••·❖·•·•·❖ .. r suPER GHosTausTER -❖, ....... ...... •,:. • t: Lt:L; I HU NIL;:;.JAYGAH ELECTRONICSJA YCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ·•·❖·,:.:,•,•··,:.•,•-:,•,•,• ' rRONICS, fRON ICS. \W 43 ELEMENT [ and UHF band 4 (SBS). 3 year warranty on workmanship- ~ f made in Australia. Suitable for all Australian capital cities. .._., f _ High gain with reflector for fringe areas. Powdercoat boom ·· { with insulators. _=,t-="'IF"""'~====-'l t Cat.LT-3151 -"------lf-- - f f ~=g~:g~: $139 rRONICS. rRONICS. rRONICS, rRONICS, rRONI CS, rRO NICS. rRO NICS. rRONICS, rRONICS, rRONICS, rRONICS, rRONICS. rRO NICS. rRONICS, rRONICS. rRONICS. rRO NICS. rRO NICS. rRONICS rRONICS fRONICS fRONICS rRONICS rRONICS rRONI CS rRO NI CS rRO NI CS rRONICS rRONICS fRONICS fRONI CS ' RONICS "RONICS "RONICS. "RONICS. "RO NICS "RONICS. "RONI CS. "RONICS. "RONICS "RO NICS "RONICS "RONICS "RONICS "RONICS. "RONICS .RONICS. "RONICS .RONICS "RONICS .RONICS "RONICS ] .RONICS .RONICS .RONICS .RONICS .RONICS 11111 .RONICS .RONICS "RONICS "RONICS .RONICS "RONICS 11 "RONICS "RONICS .RONICS .RONICS } .RONI CS "RONI CS .RONICS ,, l .,,...,...,,.,.,........... ............. • ,....., ~, • M ~"" cable. :C: ;111~ :!' ':! :;: ~~~~~ i,,i,.l,, . .......... · ~ .,.,,.,,ooou ,.,, O Backward Clock Toohoo"~~£~~~~~ • Alarm Clock Movement $14.95 , 24 Hour Clock Make your own bedside alarm clock! • Supplied with two sets of luminous hands • Alarm has on/off switch on the back • Requires 1 x AA battery Cat. XC-0104 Movement 24 hours clocks are ideal for hand radio operators. astronomers, etc. Make up you own face. • Supplied with three sets of hands • Requires 1 x AA battery Cat. XC-0101 $16.95 250gram Cat. NA-1000 .. '.' .'' ...,,,,~:,:::<at>:::::•·· ..................... ' .................... ' .................... '' ...............,,,,,,:,:,:,:,,,,,,,,.,.,.,.,.,.,.,.,.,.,,,,,.,,.,.,.,.,.,.,.,.,.,.,.,.,,,.,.,.,.,.,.,.,,,::::::~~:: • OZONE SAFE •:::r :~!~iu!!n~ isks at Silly Prices Circuit } 5.25· osoo xc-4730 La:::~~ ::i: ~~~- ~s~~D ~~::;: 175 gram Ii XC-4738 $6~95 ,';: Pot Lube 200gram f Varnish "RQNICS "RONICS "RONIC "RONIC "RONIC "RONIC "RONIC "RONIC "RONIC "RONIC "ROI-JIC "RONIC "RONIC "RONIC "RONIC "RONIC 200gram Cat. NA-1010 Cleaning Solvent [ $9.95 :::,1 ■ $6.95 Erase up to 8 chips at one time ■ Chip drawer has conductive foam pad ■ Mains powered ■ High UV intensity at chip surface ensures ■ Engineered to prevent UV exposure 175 gram Cal NA-1004 Dust Remover { ~a}o;~-~~~t tube life t $99.50 ··~ TURNYOUR SURPLUS STOCK INTO CASH!! Y' a:~1:RY 'l MADNESS :~~A2.4V 1DllmMI T~e! batteries are encased ~~c~a~~i~~~~ ;~~)~g Circuit Board Cleaner 200gram Cat. NA-1012 ii: Conductive :g~:~~ :,:::: ::f $14.95 [ $8.95 J I m 'hand' to fix it!! Or then again. make up your own clock face. I $9.00 l Suits both band 4 and 5. channels 21 to 69. Ideal for medium and difficult signal areas. Max gain 13dB. Backtofrontratio20dB. HAS YOUR OLD CLOCK DIED? Well don't throw it away, buy a quality Quartz clock movement to suit just about any clock face from Jaycar. You will be surprised to see how inexpensive they are and how professional they look. Nobody * i:~~=~er :J '\I ;:;: Cat. LT-31B1 f $75 ,....... Iiii~:h:~~oo, f ❖, :-.·❖::::~:;:;:;:; · UHF <at> Includes balun for75 ohm BEST SELLER ;;:::::w ~::::::: f ELECTRONICS, ELECTRONIC& ELECTRONICS, E CTRONIC& .,.......❖,-."::°::::::;fu"::::~t:-:❖, ... ·-:❖ :,:-:,:,:,:. .... -.:-:-:❖:•:❖·•:•:❖:❖• :•,•:❖:-:❖•❖.:❖•❖.-.: :,:-.,,:,:.,·❖:-:❖• :•:•:•:•:-:❖:-:,:-:-:,:.:,:-:,:,:•:❖:•:-.-.:,:•·..-:•:•:•:❖-:•:•:•:•:•x•:•:❖:•:•:•:•·❖:•:❖• ~~g~:g~: : Top of the line UHF/VHF TV antenna. Suitable for VHF 0-11 rRONICS, rRONICS, rRONICS. l:Ll:C I HONIC!;JAYCAR l:LcC rRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR E CTRONICSJAYCAR .ELECTRONICSJAYCAR Replacement tubes Cat. XE-4951 $19.95 thorough erase 19(H)mm. They were removed from printed circuit boards by simply cutting off the PC terminals so to use yoy would need to break open the plastic case. Inside are two 1.2V cells. So purchase 4 of these. remove 1cell and you have an 9.2V (9V 216 type) battery for only $4, not about $20. Ideal for hobbyists. experimenters, etc. To buy these today they would cost about $13 ea. Cat. SB-2470 ONLY $1 ea 10+ 90t ea 100+ 75t ea Jaycar will purchase your surplus stocks of components and equipment. We are continually on the lookout for sources of prime quality merchandise. CALL MARK HARRIS OR BRUCE ROUTLEY NOW ON (02) 747 2022 ·cfRONi CTRONI SJ CTRONICSJA YCAR CTRONICSJAYCAR CTRONICSJAYCAR CTRONICSJAYCAR CTRONIC SJAYCAR CTRONICSJA YCAR L I ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICS J AYCAR ELECTRONICS JAYCAR ELECTRONICS JAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONI CSJAYCAR ELECTRONICS.JA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJA YCAR A I: Y ELECTRONICSJA YCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRO NICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELEC TRO NICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR L H ICSJ ELECTRONICS.. ELECTRONIC& ELECTRONIC& ELECTRONICS, ELECTRONIC& ELECTRONICS.. \ .....,.,,n L..L..L..V I n v ,,., .... o <Jnl Vr\n L..LL..., I n Vl 'l l ..... ~<Jn I ...,,.,,n LLL ..... I , , v,,. ,...,,.>,Jr, I Vr\n LL..LV I n v ,,., . . . , ~ 1 v n n LLLV I , , v , ,., ....,..,._.,., IVr\n LLL V CONCORD VISA HURSTVILLE I n V l "II I V ,;,,.J M I ..... ru-, LI..LV I n v l"II I V ~ IVr\n L LL'-' 1 n Vl"lll '-'vvr'\, ..... ,.,,, \ LL..L\ AMATEUR RADIO By GARRY CRATT, VK2YBX Modem ICs make RF designs far simpler than earlier discrete transistor circuits This month, we are describing some simple home-brew converter designs based on the Signetics NE602 low-power VHF oscillator/mixer IC. Three circuits are presented: one for VHF and two for the HF bands. Last month's article covering the design and construction of a VHF frequency converter prompted many enquiries about a simpler design. And although we thought that the design presented wasn't unduly complex, we were tempted to find alternatives. Our target was to find a device which lent itself to home-brew design and which was both economical and readily available. Thanks to Signetics, there is a simpler way to frequency conversion - the NE602. This is an 8-pin DIL package IC containing a local oscillator and a double balanced mixer. Designed for VHF receiver front ends, the local oscillator will operate to 200MHz while the mixer is rated to 500MHz. Fig.1 shows the internal layout of Fig.1: block diagram of the NE602. It contains a local oscillator plus a double balanced mixer which is fed by a differential amplifier. the NE602. The combination of the differential amplifier and the mixer is known as a "Gilbert Cell". This arrangement provides up to 18dB of conversion gain at 45MHz, with a noise figure of 5dB at that frequency. At 45MHz, the IC is capable of rece1vmg input signals of -119dBm (0.3µ.V) for 12dB S/N, which means that it can easily be used on 6 metres. In addition to good VHF performance, the NE602 has very low power consumption, making it ideal for portable equipment. The IC has an onboard regulator and draws only 2.5mA at 6 volts. The input, output and oscillator ports can support a variety of configurations, the complexity generally being related to the performance. Fig.2 shows three different input circuit configurations. The input (pins 1 & 2) pins are internally biased and have .an input impedance of 1.5k0 in parallel with 3pF. The mixer outputs (pins 4 & 5) are also internally biased, allowing direct termination and also allowing for balanced output. Fig.3 shows four different output configurations three single and one balanced. Using a balanced input reduces harmonics, while a balanced output provides far superior suppression of the input RF and LO signals. Table 1 shows the advantages of ..... Y) ._____. a. Single-Ended Tuned Input b. Balanced Input (For Attenuation of Second-Order Products) c. Single-Ended Untuned Input Fig.2: three possible input configurations for the NE602 oscillator/mixer IC. 82 SILICON CHIP TABLE 1 Input Pins 1 & 2 Output Pins 4 & 5 ADVANTAGES DISADVANTAGES Single-ended No sacrifice in 3rd-order performance, simplified circuit Increase in 2ndorder products Balanced Reduced 2nd•order products Impedance match more difficult to achieve Single-ended Simple interface to filters 3dB reduction in output, less RF and LO isolation Balanced 3dB improvement in output, better LO and RF isolation at the output More complex circuitry required single ended and balanced terminations. Generally, the balanced configuration offers performance advantages but at the expense of circuit complexity. Local oscillator The NE602 on-board local oscillator is an emitter follower circuit and can be used in many different configurations. Pin 6 (oscillator base) and pin 7 (oscillator emitter) do not need any external bias circuitry. However, only pin 6 may be connected to DC supply. Pin 6 can also be used for an external oscillator or for frequency synthesiser injection. The on board oscillator can also be used 12pF liµH - ..rnlpf CFU455 OR EQUIVALENT NE602 FILTER K&L38780 OR EQUIVALENT •CT MATCHES 3.5KO TO NEXT STAGE. b. Single-Ended Crystal Filter a. Single-Ended Ceramic Filter NEI02 NEI02 c. Single-Ended IFT d. Balanced Output Fig.3: the output configuration can be either single ended or balanced, but the latter provides superior suppression of the input RF & LO signals. NE602 a. Colpitts Crystal Oscillator (Overtone Mode) NEI02 NE602 b. Colpitts L/C Tank Oscillator c. Hartley L/C Tank Oscillator Fig.4: three possible oscillator configurations. The Colpitts oscillator (a} operates in overtone mode, with L1 & C3 used to suppress oscillation at the fundamental frequency. OCT0BER1990 83 ,------------+9V ANTENNA 1k .01 ~ L2 L4 47k .,.v. .,.:B::f ;,:; IC1 NE602 OUTPUT TO RECEIVER Fig.5: this simple VHF converter uses a varicap diode to vary the local oscillator frequency so that it can tune the nominated band . The output can be tuned using a multimode communications receiver. +9V L1,3,5 : 2T, 25 B&S 3mm ID. AIR CDRED L6 = 0.2uH (approx). as a buffer for external injection. Fig.4 shows several oscillator configurations. Version (a) shows a crystal controlled Colpitts oscillator in overtone mode. Inductor 11 and C3 suppress oscillation at the fundamental frequency. Typical values for 50MHz or so are C1 = 5.6pF, C2 = . 22pF, L1 = 0.5-1.5µH and C3 = 1nF. The crystal is a third overtone type, and must be specified as a parallel mode, 5pF loading crystal. Best results are achieved when pin 6 is driven to 200-300mV peak to peak, The NE602 has some obvious advantages, including very low power consumption for very good performance. There are also some characteristics which are not so obvious. As a result of the very fast bipolar process used by the NE602, the phase integrity through all three ports is superb. This aspect makes the IC an ideal choice for image rejection mixer applications. And although Signetics specifies the device for use up to 200MHz, the NE602 has been used to 900MHz (although Signetics won't guarantee performance beyond 200MHz). Simple VHF converter Fig.5 shows a simple VHF receiver using the NE602. This particular design uses a varicap diode to allow the user to vary the LO frequency, so that the receiver can tune the nominated band. With the addition of an FM IF strip, the receiver would be quite useful on the VHF and UHF amateur bands. The addition of a simple AM diode detector would result in quite a good air band receiver. Alternatively, by feeding the output to a multimode communications receiver you would get the best of both worlds. Of course, the NE602 is not restricted to VHF or UHF use. The IC can also be used as a frequency converter at HF. Fig.6 shows a simple up-converter which will allow long-wave signals in the 300- 500kHz band to be received on a shortwave receiver tuning 4.34.5MHz. Fig.7 shows a direct conversion receiver for the 40-metre band. Both designs use easy-to-obtain IF transformers in the front end tuned circuit. However, any transformer covering a suitable frequency band could be used. Further reading (1). Signetics Linear Data and Applications Manual Vol.2, 1985 (2). Radio Electronics magazine, April 1990. (3). Signetics Application Note AN1981: New Low Power SSB Circuits. (4). Signetics Application Note AN1982 (5). Signetics Application Note AN198: Designing with the NE602. Footnote: the NE602 is available from Stewart Electronic Components, PO Box 281, Oakleigh, Vic. 3166. Phone (03) 543 3733. 300·500kHz 330pF Tl 455kHz IFT 47pF ;--!¥'--, ,1i;,-~1_ _ _____, 330pF I I VC1 I IC1 N£602 .001 ~OUTPUT 4.3MHz-4.5MHz .,. Fig.6: use this up-converter circuit if you want to receive long-wave signals in the 300-500kHz band. The output can be tuned using a shortwave receiver (4.3-4.5MHz). 84 SILICON CHIP IC1 NE602 .,. Fig.7: here's a design for a direct conversion receiver for the 40-metre band. The output can be fed directly to an audio amplifier. AUSTRALIA'S DYNAMIC ELECTRONICS MAGAZINE They said we'd go broke but we didn't! Did you have doubts when we started SILICON CHIP? Many people shook their heads and said we were headed for disaster! It may not seem all that long ago but it's now almost three years since SILICON CHIP came onto the scene. According to most people, we had NO chance at all of succeeding. To tell the truth, we probably were a little foolhardy but we started off anyhow. We thought there would be enough readers out there who would appreciate what we were trying to do. Thankfully, enough of you have made the decision each month to buy SILICON CHIP for us to survive and grow. Our special thanks to those readers who took out a subscription in our early days - they helped us enormously. In fact, they probably made the difference between our survival and failure. So now it's three years down the track. You might have noticed how the issues have been growing, bit by bit, starting first at 96 pages, then 104, then 112 and now, with this issue, 124 pages and with a growing colour content too. Some readers have even commented that they were amazed that we have kept the price of SILICON CHIP so low for so long. After all, the price of everything else has gone up in the last 3 years hasn't it? What about SILICON CHIP? "Uh oh", I can hear you muttering, "He's just about to announce a rip-off price increase for SILICON CHIP". Well NO. We plan to hold the price of SILICON CHIP constant for as long as possible. Yep. We know that you like to see SILICON CHIP on sale at a good price each month. But we need you to help us with that. To help us hold the price of SILICON CHIP for as long as possible, we're asking you to take out a subscription. Presently, you may like SILICON CHIP but maybe you don't buy every issue. Possibly you like to flick through each issue and ••• then decide to buy. Well, if you think SILICON CHIP is good, why not buy it every month? That way, you'll have access to all the articles and you won't regret having missed an important issue. If you decide to take out a one-year subscription, you'll be helping us a lot. For our part, we'll have SILICON CHIP delivered to your door in mint condition, generally a few days before it goes on sale in newsagents. You'll know about the specials from SILICON CHIP advertisers, before they run out! And to sweeten the deal, there is our big subscription promotion, starting this month, featuring a Bose Lifestyle Music System as the grand prize. It's well worth being in the draw by becoming a subscriber. And another point. If you work in electronics, a subscription to SILICON CHIP could be partly paid for by Paul Keating (yes, a tax deduction). Check your eligibility for a deduction with your accountant. Your Guarantee of Satisfaction And what about if you take out a subscription and then decide that you don't want SILICON CHIP delivered every month? That's OK. We understand that this might happen with some readers. So, to overcome any reluctance you might have on that score, we will refund the balance of your money if at any time you decide the cancel your subscription. Please take a few moments now to fill out the coupon on the back of this page. Send it with your remittance to us and we will start your subscription with the next issue. I know you will enjoy"reading SILICON CHIP for the next 12 months and I thank you for your enthusiastic support. Leo Simpson Publisher FILL OUT THE POSTAGE-FREE SUBSCRIPTION COUPON OVERLEAF OCT0BER1990 85 I I ORDER FORM -- RATES: NEW SUBSCRIPTION: Month To S t a r ~ - - - - - - - (PLEASE TICK ONE) RENEWAL: Sub No. _ _ _ _ _ _ Start In _ _ _ _ __ Australia Australia W/Binder NZ & PNG (Airmail) Overseas Surface Mail Overseas Airmail QGIFT SUBSCRIPTION: Month To S t a r ~ - - - - - - GIFT SUBSCRIPTION DETAILS "D ! 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YEAR ISSUE YEAR ISSUE YEAR ISSUE YEAR n C -4 -4 :z: m I: ► 0 t i m TOTAL $A Enclosed is my cheque/money order for $_ _ _ _ _ __ orpleasedebitmy ■··. Ila Card No. 1,..1 ~n llliiiiiilJi...t So ~ Mr/Mrs/Ms: _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ Address: _ _ _ _ _ _ __ __ __ _ _ _ __ Card expiry date Signature, _ _ _ _ _ _ _ __ 86 _ _ _ _ _ _ _ _ Postcode:_ _ _ _ _ _ __ 24 Hour Fax Service Subscription Hotline (02) 979 6503 Send the coupon with your Credit Card Details. 24 Hours, 7 Days a week. Telephone (02) 979 5644 9am-5pm Mon-Fri and quote your Bankcard, Visa Card or MasterCard No. and expiry date. SILICON CHIP Detach and Mail to: FREEPOST 25 SILICON CHIP PUBLICATIONS PO BOX 139 COLLAROY BEACH NSW 2097 No stamp required in Australia COMPUTER BITS By JENNIFER BONNITCHA Now what's gone bung?!! Just when you thought it was safe to go back to your computer, another problem arises! This time the *#&% printer doesn't want to co-operate. But before going overboard about printers, let's take a little time to examine the communication ports and therefore the two major kinds of printer connections - parallel and serial. The basic communications ports in any PC system are the parallel and serial ports. The parallel port is used primarily for printers and operates as a one-way communications port. The serial port allows bidirectional communication with any system using devices such as modems, mice, scanners, digitisers and of course serial printers. Serial devices are capable of sending and receiving information from the PC while the parallel device can only receive information and so usually does not have too much say at all in what goes on. Synchronous & as~nchronous The asynchronous serial interface is the primary means of system-to-system communications. In this type of transmission, cha racters are "marked" with start and stop bits. The PC with its Asyn- chronous Adapter uses a binary O (zero) for the start and stop bits. The word asynchronous means that no clocking signal or synchronisation is present. Characters can be sent with any arbitrary time spacing, so the intervals between the characters may be completely irregular. A standard start and stop signal frames each individual character. The start bit is a single O bit which precedes each character. It's job is to tell the receiving system that the next 8 bits make up a byte of data. One or 2 stop bits follow the character to signal that the character has been sent. At the other end, characters are recognised by the start and stop signals rather than by the timing of their arrival. The asynchronous interface is character oriented and has approximately 20% overhead for the extra information needed to STOP BIT l J START BIT f _____o_A_r_,,~.._s_,r_s_ _ _ ARITj B(IT 0 0 1 0 0 0 0 0 11 0 Fig.1: basic format of an asynchronous data transmission, in this case for the letter "A". A start bit is transmitted first, then the data, parity & stop bits. identify each character. In contrast, synchronous transmission refers to a communication mode in which each character or sequence of bits is sent down the line in a strictly-timed rhythm. Thus, both the sending and receiving devices must be "in tune" for the information to be received in an intelligible manner. The use of a timing marker at each end means the receiving device can "know" where each ASCII character begins and ends and therefore precisely which character has been sent. Though advantageous at high speed, sophisticated timing circuitry is required at both ends of the transmission. High speed synchronous transmissions also require high cost devices to control the data flow. Parity checking During data transmission, an extra bit of information is usually added to each ASCII character for error checking purposes. This parity bit is usually set at the transmitting end by the program handling communications. Parity may be high, low or no parity and is computed by adding up the number of "1" bits in the data field. The result of this addition is the parity checksum. Parity checking is the most basic method or error detection and most data communications systems use even parity for data exchange. Data checking takes place at the receiving device where the communications software does a checksum on each incoming character and compares its calculation of parity with that sent by the transmitting computer. If any of the bits has been reversed (eg, by noise OCT0BER1990 87 COMPUTER BITS - CTD on a telephone line, radio frequency interference etc], then the receiving side of the system should be able to detect and report the error. Parity checking is the easiest method of error detection since it relies on the statistical fact that having two bits in a character change during transmission is a very rare occurrence. If two bits should change then parity checking won't detect the error. Serial vs parallel Serial transmission means that data is sent over one wire with each bit lining up in a series as they are sent in order. Thus, to move one byte you must send eight signals, one after another. A serial transmission is slower than a parallel transmission, but the speed of the printer is so much slower than the transmission speed that the serial interface mode generally won't limit printing speed. This type of communication is used over the telephone system because it provides one wire for data in each direction. The control program for the serial port is in the ROM BIOS on the computer's motherboard. Serial ports may connect a wide variety of devices such as modems, plotters, printers, other computers, barcode readers, fax cards, scales and so on. Anything which requires a 2-way connection to the PC uses the "industry-standard" Reference Standard number 232 revision c (RS-232c] serial port. This device enables data transfer between otherwise incompatible devices. However, the most common connections to the serial port are modems and printers. Generally, the PC BIOS and operating system handles only two serial communications links: COMl and COM2. You need to ensure that two serial ports within one system do not conflict. Every board supplied is automatically set up as COMl so you need to reconfigure any additional ports (usually by setting DIP switches) for COM2 before 88 SILICON CHIP use. But two ports are barely enough nowadays. With the advent of the PS/2, the use of more than two serial ports became more of a reality. Most pieces of hardware in your computer communicate with the Central Processing Unit [CPU] via signals called interrupts. The signal literally interrupts the CPU and tells it which device requires attention. As the following table shows, the "industry standard" 1/0 addresses of the four serial ports are all unique. However, the interrupts overlap. TABLE 1 Port COM1 COM2 COM3 COM4 1/0 Address 3F8 2F8 3E8 2E8 hex hex hex hex Interrupt 4 3 4 3 Using two interrupts for the same port seems like suicide, however you could use one port from each pair (COMl or COM3; COM2 or COM4) while using the other port in the pair without interrupts. The key to success is the use of "interruptdriven" [eg, communications and mouse software] and "noninterrupt-driven" applications. You could use a modem program on COMl and a serial printer assigned to COM3 using the DOS Mode command. Even though each uses the same interrupt, COM3 will never try to use its driver circuit to control the shared interrupt line. The parallel port has eight lines for sending all the bits for one byte of data simultaneously across eight wires to the receiving device. This interface is fast but with eight wires required to send the information, the cost of cables starts to increase and so this method of communication is usually reserved for the short distance to printers. The only real problem with parallel ports is the cable distance limitation due to the lack of signal error checking. One byte of infor- mation is sent in one transmission since one bit can be sent over each of the eight wires. Parallel ports are unidirectional. Data travels in only one direction from the computer to the port and then to the parallel device. The newer PS/2 computers have a bidirectional parallel port however, so data can travel to or from the port. Problems with serial and parallel ports can often be detected using diagnostics software and a wrap plug for each type of port. To test any serial or parallel port cards, run your computer's advanced diagnostics communications adapter tests. Typical error codes displayed are shown in Table 1. For serial ports only, check for a voltage reading of - 10.BV to - 12.9V DC between pins 4 and 8 [ground] and the system board power connector. If the voltage measurement isn't within the range specified, the power supply may be defective. Many problems stem from using the wrong serial port card in a system. The main difference in serial ports is in the Universal Asynchronous Receiver Transmitter [UART] chip which is the primary port circuit. The system ROM BIOS is designed specifically to support certain chips and so some chips can only be used in certain systems. If you use a port with the wrong UART, problems such as port hanging, incompatibilities with software, lost characters or total function failure are not uncommon. Printer problems And so finally to printer problems which can manifest themselves in a myriad of ways. Starting with the most obvious problems, check: • printer power on and power cord securely connected to both the printer and power outlet; • printer is "on-line" or "selected"; • printer is not out of paper; • the printer cable is securely connected at both the computer and printer. Check again for security, even if you think all is OK; • the DOS Mode statement has from tractor feed to cut sheet feed, etc. Paper smudge on a dot matrix printer usually means the paper thickness control is set incorrectly. If the print head is too close to the paper, smudges occur as the printer moves across the paper this typically happens when a new ribbon is installed or a thicker than usual paper is used for printing. Change the thickness control as required. COMMON ERROR CODES 9xx 901 10xx 1001 11 XX 1101 12xx 1201 Parallel printer adapter errors Parallel printer adapter test failure Alternate parallel printer adapter errors Alternate parallel printer adapter test failure Asynchronous communications adapter errors Asynchronous communications adapter test failure Alternate asynchronous communications adapter errors Alternate asynchronous communications adapter test failure been set correctly for a serial printer - much of today's software will set the communications parameters automatically, but check just in case. Next, you could try a little more problem determination: • Perform a Power On Self Test (for most printers, turn the power off and then, while holding down the Line Feed (LF) or similar button, turn the power back on). A sample pattern should now print. If not, check your printer manual for further information. • If the printer test functions correctly, try a "screen dump" of any information [other than graphic images) from your computer. Press Print Screen or Shift PrtSc to send the information to the printer. If you get no response, try something simple [swap printer cables, for example). If the print screen works correctly but you still get "junk" reports, check the software configuration. Is the program set up correctly for your printer type [serial or parallel) and model [not just manufacturer) of printer? For laser printers, is there an operator message to indicate the need for toner or a new OPC drum? For dot matrix printers (especially those using film type ribbons), is the ribbon exhausted? BIT PULSES _ _ _ _ _ _A _ _ _ _ _ __ ( 1 0 0 Q Q Q ' For programmable printers [typically dot matrix and laser), check the system settings. It is possible that someone may have changed the inbuilt settings and thus altered the mode of operation - eg, changed the printer program BIT PULSES _ _ _ _ _ _A...__ _ _ _ __ (1 0 0 0 0 0 ' 1 TO PRINTER Parallel Transmission Fig.2: in parallel transmission, the data bits are all sent to the port simultaneously via separate lines. The data travels in one direction only, from the computer to the device. Missing characters Characters "missing" or not fully printed on dot matrix printers usually indicate that the ribbon is not correctly seated or a pin in the print head may be broken. Check ribbon operation before panicking further. Inkjet and thermal wax printers can suffer from clogged jets and insufficient temperature of the print head, thus causing problems with the dye or wax mixing. The appearance of vertical streaks on laser printouts is a sign that the corona wires need cleaning. Refer to your printer manual for more details. While most printer problems are operator-related [sorry team, but that's the truth, the whole truth and nothing but the almost truth), there are times when a call to a technician is the only answer. Use common sense and you should be able to avoid any unnecessary expense. And always remember to try the simple things first. Go for the least expensive items [like printer cables) and work your way upwards in cost. By their very nature, it is often the simple, low cost items which fail first. Next month, we'll talk about cables and give some tips on avoiding cable mixups. ~ Serial Transmission 1 ----c?:__ _ _-Jl_,..lQ)=====:j) ) TO PHONE '-'--------- LINES Fig.3: in serial transmission, the data is sent one bit at a time over one line (ie, each bit is sent in sequence}; Serial transmission is the method used for sending data over the telephone system. Because there are two lines, data may be sent in either direction. OCT0BER1990 89 GOODWILL GOS-622 20MHz 2CH. OSCILLOSCOPE HS-3000 Plus HANDY SCANNER "THE TOTAL SCANNER SOLUTION" For uses with: DESKTOP PUBLISHING WORD PROCESSING CAD APPLICATIONS DATA BASE WIDE 4.13" (105mm) SCAN WIDTH 100/200/300/400 SWITCHABLE DPI RESOLUTION WAS $499.00 NOW ONLY * * Display: CH1, CH2, DUAL, CH1, CH2, X-Y. * Sweep Modes: Auto, Normal, Single Shot. PLUS FREE Auto Trigger Level Lock, Variable Hold-Off. DIGITAL Sensitivity: 5mV/DIV to 5V/DIV to 20MHz. MULTI-METER * * INCLUDES 2 x 1:1 10:1 PROBES * ONLY $385 PORTASOL "PRO" GAS SOLDERING IRON KIT * $799.oo 12 MONTHS WARRANTY 1600 WATT HEATGUN - Two heat settings: 400°C/600°C. Great for heatshrink tubing, paint stripping, or bending PVC pipes. .,0 ,<,. Designed for the craftsman, technician, or ~~ professionals requiring micro-precision soldering with ~ C' adjustable power equivalent to 60 watts. ~ "9-i, Complete kit includes Portasol tool, 4 tips (Soldering o iron, Blow Torch, Hot Blower, Hot Knife), safety stand , ~ cleaning sponqe and handy storage case. d' AALEC: q. QUALITY PADUUCT5 <?,, ONLY $55.oo ~-~ RECHARGEABLE every purchase "DRILL 'N' DRIVE" NOW Two speed cordless Drill and Screwdriver. $59.95 HDS-90L PROBE TYPE DIGIT AL MULTI METER VIDEO TRANSMITTER NORMALLY $599.00 NOW ~ / $549.oo Output power: 140W RMS into Bohm. I \.--i 200W RMS into 4 ohm. Distortion: 0.005% at 1OOW into 8 ohm. Frequency response: 1OHz to 1OOkHz. Ideal for watchirig a video in the bedroom, kitchen etc. without having to move your complete VCR system or having long extension cables running from one end of the house to the other. * Output channel: UHF 30 * Transmitting distance: 1Omtr. * Complete with power supply and connecting cables. ONLY * $89.95 127 YORK STREET SYDNEY 2000 PH: (02) 267 1385 BUSINESS HOURS: Mon-Fri 8:30 to 5:30, Thurs 8:30 to 7:00, Sat 9:00 to 1 :00 * CASSETTE TAPE ERASER MULTI-LINGUAL POCKET TRANSLATOR Simply pass the cassette through the eraser several times. • No batteries or liquids required. Ideal tor travellers, students, business people and holiday makers. • Instant word conversion of ENGLISH, FRENCH, GERMAN, SPANISH and ITALIAN. • 1,400 words in each language. • Light and easy to carry. ONLY $7 .95 CASSETTE SALVAGE and REPAIR KIT • Complete set of cassette parts. • Mylar splicing tape. • Complete with splicing bar and razor blade NOW ONLY $59.95 only $2.95 Ill t-•STUDIOU~~~ ~l~NTROL • SLIM ONE RACK PROFILE • FULLY PUNCHED AND PRINTED PANELS - STUDIO 200 SERIES 1OOW/PER CHANNEL AMPLIFIER only $99.95 LM833 1.C. ONLY $ 2.25 ea -DUAL HEADPHONE EXTENSION LEAD POCKET SIZED AUDIO SIGNAL GENERATOR STEREO 6.5mm PLUG to 2 x 6:5mm STEREO SOCKETS on individual 8 metre cords. only $6.95 ea. • Sine and Square wave output. • Freq . range: x 1 range 20Hz to 1.5KHz x 100 range 2KHz to 150KH • Output control: OdB, -20dB plus fine adjuster • Output impedance: 600 ohm +/· 10% • Operates on a sinQle 9 volt battery LIGHT WEIGHT STEREO HEADPHONES • • • • I Freq. Res. 20Hz to 20KHz Impedance 32 ohm 4 ft. lead with stereo 3.5mm plug 3.5mm ST. skt. to 6.5mm ST. plug adaptor inc luded LM837 I.C. ONLY $3.50 ea * NOW ONLY $95.00 PRO-SERIES 3 WAY CAR SPEAKER SYSTEM ARLEC POWER SURGE PROTECTOR • 40 Watts power handling. • Freq. Res. 80Hz to 20KHz. _•.Size 180x107x131m* .•. NOW ONLY .· $49.95/PR • Surge Capacity: to 4500 Amps. • Maximum continual voltage: 275 volts. • Reaction time: less than 25 nanoseconds. • Clamping voltage: 71 O volt, 50 amps. • Energy absorption factor: 75 joules. NOW ONLY $21.95 PRO-SERIES CD101 0A 5.25" DUAL CONE CAR SPEAKER • 45 watts. • SPL. 94dB NOW ONL y • 4 ohms • Complete with grilles. $59.95/PR • Fre . 90 to 19KHz. MAIL ORDERS: P.O. BOX 0103 SYDNEY 2000 PHONE ORDERS: (02) 267 1385 FAX: (02) 261 8905 I~ POST & PACKING $5-$25 $26-$50 . . ~--- <· '. .·. · . Ideal for computers, tv and videos, etc. "'-·-- - ·MORE SPECIALS IN THE FRONT OF THIS MAGAZINE $3 .00 ... $5.00 $51 -$100 . $101-$499 . j tE MAILBAG 4-digit capacitance meter clarification I was interested to read the description of your 4-digit capacitance meter in the May 1990 issue. However, I feel I must corn-. ment on the claimed accuracy of ± 1 % plus one digit. This accuracy is certainly achievable by the instrument itself, but only if calibrated by a NATA laboratory, or similar. If calibration is done in the manner described in the article, the achieved accuracy is, unfortunately, only ± 3 % plus one digit. You propose using a 1 % capacitor of 0.1!,tF value on the 999.9nF range and adjusting the calibration pot until the display reads 100.0. Then, " the other ranges will automatically be correct". Not so. For any other range you have three 1 % errors involved in the reading that of the calibrating capacitor, that of the lO0kQ resistor on the calibrating range, and that of the resistor associated with the range in use, a total of 3%. The 999.9nF range would be within the claimed accuracy of ± 1 %. I have been trying to think of a way around this problem but all I can think of is to calibrate with a 0.1 % resistor in the calibrating range and a calibrating capacitor of a similar accuracy, if such things are available! P. Badham, Frenchs Forest, NSW. Comment: yes, your points about accuracy are well made. The typical accuracy, allowing for the standard deviation of the three 1 % components in the calibration, would probably be close to 1 %. However, the "worst case" accuracy, with all three components 1 % high or all 1 % low, would be 3.03 % since the errors multiply rather than add. As far as we know, capacitors with 0.1 % accuracy are not readily available. However, it would be 92 SILICON CHIP worthwhile contacting Allied Capacitors (at Unit 6/25 Chard Road, Brookvale 2100; phone 938 4690) who probably would be able to wind capacitors to this very close tolerance. Microwave cooking saves energy I read with interest the letter in Mailbag in the August 1990 issue by Kenneth S. Jaffrey headed "Microwave Cooking Destroys Good Food". Mr Jaffrey's 60 years of experience in the field of nutrition leads him to believe microwave cooking is neither safe nor beneficial. An elaboration of this opinion is probably beyond the scope of an electronics magazine. However, the statement that microwave cooking is a more expensive way of cooking requires explanation. As an electricity bill conscious technician, my sums (ie, power consumption x cooking time for a microwave versus power consumption x cooking time for an electric stove) come up in favour of the microwave. Perhaps Mr Jaffrey was comparing the microwave to gas or wood stoves. Thanks for a good magazine. D. Downie, Beenleigh, Qld. PS: the FRG7700 versus 51J4 was terrific. How about a look at the current Collins receiver. Is it miles ahead of the opposition? I bet it doesn't have mechanical filters any more. Wants more radio comparison articles Thanks very much for publishing the article in the August 1990 issue comparing an old Collins 51J4 (R388A) receiver with a modern one. These old receivers can certainly show the Japanese-made ones a thing or two! It would have been interesting if SILICON CHIP, PO Box 139, Collaroy Beach 2097. a Collins R-390A had been chosen instead. These sets are considerably superior to the 51J series, being designed for the (US) military in 1955/6 as a cost-effective replacement for the R-390/391. They are considered by many to be amongst the best receivers ever built. I have one of these receivers here - mine was built by Hammarlund under contract - and personally, I would not change it for a million dollars! Or, perhaps I should say, a million yen since I do some monitoring work for Radio Japan with it. One last thing - these old sets are much admired in Japan. They sell for thousands of dollars according to some advertisements I saw in an amateur magazine I brought back with me after a recent trip to Tokyo. The folk at Radio Japan were most impressed when I told them what shortwave receiver I used. T. Robinson (VK3DWZ), Woodend, Vic. Subscriptions usually arrive early Enclosed please find my order for an April 1990 issue of SILICON CHIP. I would have taken an annual subscription if it were not for the fact that many magazines usually appear in the newsagents a week before subscribers get them in their mailbox. I just can't wait that long! If not so, please write it up in your column. Tom Langenberg, Mt Riverview, NSW. Comment: subscribers to SILICON CHIP normally receive their copies a couple of days before they appear in the newsagents. They are packed in a tough waterproof plastic bag so they arrive in mint condition, even in wet weather. 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Unbeatable performance and value ■ Three year warranty ■ 3½-digit, 3200-count display ■ 31-segment'analog bar graph ■ Single rotary dial to select all functions ■ Autoranging and automatic polarity selection ■ Batterysaving "Sleep Mode" powers-down display if you forget ■ Tough, textured case resists drops and rough handling ■ Touch Hold® (Fluke 77) ■ UL 1244 listed ■ Made in U.S.A. 73 - D.C. Voltage 0.7%, A.C. Voltage 3% Autoranging $150 ex tax - $175 incl tax 75 - D.C. Voltage 0.5%, A.C. Voltage 2% Autoranging with range hold, audible continuity/diode test $240 ex tax - $280 incl 77 - D.C. Voltage 0.3%, A.C. Voltage 2% Touch Hold® $325 ex tax - $379 incl tax te=l-:r'l-:THs~ Also call us for Signal Generators, Power Supplies, Counters, and any other T & M requirement. Full range of Fluke/Philips Accessories. T & M PTY. LTD. Call Tim Wortman the specialist Fluke/Philips Distributor TECH-FAST T & M PTY. LTD. 14B MAXWELL STREET, TURRAMURRA N.S.W. 2074 TELEPHONE: (02) 988 3865 FAX: (02) 988 3861 A helicopter is handy for inspecting high voltage power lines - provided one doesn't get too close!' These are 330kV transm~ssion lines from Vales Point in NSW. 94 SILICON CHIP The Story Of Electrical Energy, Pt.4 The huge quantities of electrical energy generated in modern power stations must be carried to the users, homes and industry. In this episode, we look at modern high voltage transmission lines, their design, construction and the materials used. By BRYAN MAHER Though city dwellers take electricity for granted, the recent storms and floods around Australia have served to remind us of our dependence on light and power. To live, work and travel, we all need electric power. In previous chapters, we looked at the outstanding engineering effort needed to generate the electricity supply. Now we look at how that power gets to the people. Not surprisingly the longest power transmission lines are found in the largest states. Furthermore, heavy industry needs heavy electricity systems. Queensland, the largest eastern state, has over 4000 kilometres of 275kV lines, running almost the length of the east coast. The total length of all high and low voltage circuits is almost 170,000 kilometres. Gladstone power station, the ma- . jar source of Queensland's electricity in the early 1980s, is approximately 500km from Brisbane. Therefore, a number of 275kV lines carry 1000 megawatts (1 Gigawatt) or more of power over tp.is long distance to Southpine substation just north of Brisbane. From there, 275kV lines run to Swanbank (near Ipswich), Belmont and Mudgereeba (Gold Coast) substations. At these main substations, the voltage is transformed down to 110kV for distribution to 17 smaller substations in the Brisbane area and 8 on the Gold Coast. In areas north of the Sunshine Coast, 132kV is the intermediate voltage used. At each substation, power is again transformed down to 33kV or 11kV. Finally, the 11kV system distributes the power to hundreds of small street substations. It is here that the final stepdown to 415/240V 3-phase street mains takes place to feed your home and local industries. Many large buildings and industries are supplied at high voltage, often 1 lkV. A few very large industrial plants, such as aluminium smelters, purchase power at 132kV. Similar situations exist in all Australian states, cities and towns .. The first 330kV line This is what high voltage switches look like. These are 11kV 400-amp air break switches, in the open position. Notice the double current carrying blades and the steel spring arc horn set at 45°. This breaks the current last to stop arcing to the main blade. The backbone of the NSW system is the 5000km network of 330kV lines running the length of the state. The first line of this voltage in Australia was constructed from the Snowy Mountains Hydro power stations to Yass substation in 1960. Canberra also receives power in this way. OCT0BER1990 95 These 330kV transmission lines south of Armidale are very unusual because they use wooden poles. Notice the "dog bones" on the cables, near the insulators. These are vibration dampers, used on all transmission lines with conductors of more than 20mm in diameter. Weighing a kilogram or more, they damp vibrations of 7 to 16Hz. The 330kV system was extended to the Riverina and Victoria in the south, to Wellington in the west, to the Wollongong-Sydney-NewcastleHunter Valley complex and as far north as Armidale. Extensions to Coffs Harbour and Lismore are in progress. An intermediate system of 8600km of 132kV lines distributes electricity to area substations over the whole state. 500kV line Sydney's metropolitan area consumes 48 % of all energy generated by the NSW Electricity Commission. The heaviest transmission system in Australia is the 500kV twin line from Eraring power station to 96 SILICON CHIP Kemps Creek, Sydney. This same voltage is also used in Victoria. Also in NSW is the 224km 500kV circuit from Bayswater in the Hunter Valley to the new Mt Piper power station [between Wallerawang and Mudgee). This line is temporarily energised at 330kV until Mt Piper is completed and on line. Why all these different voltages? One of Australia's earliest major interconnectors was the 66kV line built in 1942 to link Hamilton [Newcastle) and St Leonards substation in Sydney. It was constructed using 19-strand 10-ga uge cadmium copper for the longest span across the Hawkesbury river and 37-strand 12 gauge hard drawn copper elsewhere. That line, capable of carrying 200 amps, was built as a strategic link between power stations during World War 2. At the time, small towns in between Newcastle and Sydney were without electricity even though this line ran along their main streets. In 1943, the citizens of Wyee petitioned for a substation to serve their area. Unfortunately, a 66kV transformer to serve a very small load would have been hopelessly uneconomic, so their request was denied. Today an 1 lkV line from a different source and a small substation supplies Wyee. So most of the power is distributed via llkV lines in the suburbs. But why must transmission lines go as high as half a million volts? Indeed, higher voltages still are found overseas. In England, Europe and the USA, voltages up to 1.2 million volts are used. And modern research is always pushing the limit higher! Why? Consider a simple system of one source [a large power station) and one load [a big city), separated by great distance. Here we have a problem. Naturally, there will be power losses due to resistance in the transmission lines, but being an AC system, there will be inductive and capacitive losses too. The inductance losses exceed those caused by resistance in most high voltage power lines. The inductive reactance may be from 8 to 23 times greater than the value of resistance. Typically, with conductors ranging from 25mm to 50mm in diameter, inductive reactance ranges [overseas) from 0.2 to 0.5 ohms/km, while the resistance is .01 to .075 ohms/km. Hypothetical design Suppose we propose a 10kV line to supply 3GW to our hypothetical city from its remote power station. That implies a line current of 200,000A. Wow! A little arithmetic soon shows that even with the very low resistive component of 0.02 ohms/km, such a current flowing would produce a voltage drop of 4kV/km along the line. Clearly, this is an impossible situation; and the inductive effects are greater still! Obviously, we must either install conductors which are a few thousand times thicker or use a very much smaller current. The former choice would be ridiculously uneconomic in lines of great length. Therefore, we are forced to use smaller current. How? Just transform the supply up to say 50 times higher voltage, say 500kV and hey presto! The current will then be 50 times less, at 4000A. The voltage loss along the line due to the resistance will now be only B0V/km, and the inductive drop will also be down to manageable values. Now we see why very high voltages must be used. Indeed, over long distances, the power that can be successfully transmitted depends roughly on the square of the line voltage. Insulators Very high voltages bring their own problems though. For starters, longer strings of insulators must be Not all transmission towers are massive structures as this photo of Swedish 400kV lines shows. Using guyed towers, the structures are quite light. Note the use bundles of three conductors for each phase. This technique reduces inductance & corona losses by simulating a conductor with a much larger diameter. used, increasing the cost and the weight suspended from the towers. Up to 132kV, we might see either solid standoff insulators, or strings of multiple suspension disc units linked together. Either steel towers or wooden or reinforced concrete poles are used to support lines up to 132kV. Above this voltage we usually see only steel towers. In a few places though, timber poles support 330kV lines; eg, on the northern NSW tablelands just south of Armidale. Fewer insulators are needed on a line if less towers are used, so longer spans save dollars. But longer spans require bigger and more expensive towers; balancing the costs is a finely tuned exercise. Conductor materials After more than 50 years of use, the traditional hard drawn copper and cadmium-copper cables have lost favour with power line designers because of their cost, relatively low strength and high weight. Today, cables usually use pure aluminium for short spans which are under low mechanical tension. More sophisticated materials are used for long spans to withstand greater strain. Most high voltage lines are strung very tight, up to 25 % of the ultimate tensile strength. This minimises conductor sag and swing and thus longer spans and less towers can be used. High tensile strength is necessary to take the continuous strain of conductor weight, plus the considerable wind forces sometimes experienced. Between Newcastle and Sydney, the strongest winds expected are the short powerful gusts associated with thunderstorms. These may gust to over 170km/h at ground level, and 200km/h at conductor height. OCT0BER1990 97 AAAC conductor This 330kV transformer is installed at Wellington Substation in the central west of NSW. It steps the 330kV down to 132kV for regional distribution. Many cables are now constructed using ACSR, which stands for Aluminium Conductor Steel Reinforced. This employs many strands of aluminium surrounding a stranded core of galvanised steel. The current flows mainly in the aluminium while the steel core gives strength. One common size is seven strands of steel (2 layers) encased by 54 of aluminium (3 layers] - a total of 61 made up in concentric rings. The relation between layers and number of strands is given in the accompanying table. The layers are skewed slightly to hold the cable together, as in rope. Consecutive layers skew in opposite directions for stability. This skew, called the lay of the cable, increases strand length and hence the resistance per km by a small amount. Sometimes the steel core uses 19 98 SILICON CHIP strands of a smaller gauge wire, for greater flexibility. Another type of conductor is ACAR, or Aluminium Conductor Alloy Reinforced. In this, the aluminium conduction strands surround a stranded core of aluminium alloy. The manufacturers of this cable claim lighter weight, less corrosion and easier splicing. CABLE CONSTRUCTION Layer No. 1 2 3 4 5 6 7 8 Number Of Strands 1 6 12 18 24 30 36 42 Total Strands 1 7 19 37 61 91 127 169 (Note: all strands equal diameter) The ABB company and their associate Elektrokoppar of Helsingborg, Sweden, manufacture AAAC, an all-alloy cable which goes by the trade name DuctaLex. This alloy is 59% as conductive as copper but transmission losses are lower because there is no steel core. The alloy used is based on aluminium/magnesium/silicon and is claimed to give low weight, high Young's modulus of elasticity (up to 67kN/mm2), low creep (400ppm), high surface hardness and corrosion resistance, and reliable jointing. The first commercial use of this alloy in a power line was in a 400kV Swedish system built in 1977. Because of eventual metal fatigue, transmission lines may have a working life of 30 years. If then dismantled for scrap metal value, DuctaLex cable can go to the melting pot whole. However, scrap ACSR must first be separated out into its steel and aluminium components, and this reduces its value. Fully 80% of Swedish power lines now use alloy cables. In Australia, Alco makes a cable with similar properties. The small additives (0.7% Mg and 0.6% Si) give great strength to this aluminium alloy. Another alloy of aluminium/copper/magnesium is also used. Eraring to Kemps Creek From Eraring power station on Lake Macquarie, near Newcastle, twin 500kV lines run for 143km to Kemps Creek substation in Sydney's western suburbs. Here the voltage is transformed down to 330kV to be fed into the state grid at Sydney-north, Sydney-south, Avon and Dapto substations. Between Eraring and Kemps Creek substation, the 500kV lines run inland, crossing the remote Hawkesbury regions, then the western railway at Werrington station. From there, it follows South Creek, Mamre Road and Kemps Creek. Carried on galvanised steel towers, typically 55-metres high, the cable spans vary in length ac- Tough enough to take it, wherever you take it These 132kV 3-phase transmission towers distribute electricity to substations in the Canberra district. Notice how each phase consists of a 2-cable bundle to reduce line inductance & corona discharge. cording to the terrain but are commonly 400 metres to 900 metres. Much longer spans, up to 1.5km long, are sometimes used in isolated areas where the towers are located on mountain tops. The twin line construction used on the Eraring-Kemps Creek system has two complete 3-phase lines per tower. Compared to the alternative method (two separate sets of towers, each carrying one trio of 3-phase lines), the twin construction method uses less towers and occupies a much narrower land corridor. But twin lines are also less isolated from each other inductively and capacitively. Again, the design is a careful compromise, as we shall see. Conductors Fluke 80 Series multimeters come in a rugged, water and dust resistant case. They can handle up to 1000 VAC (RMS)/DC on any terminal and have an "input alert"™ warning if test leads are in the current jacks and a non-current function is selected . They are shielded against electromagnetic interference and are protected against shock and vibration. Each Fluke 80 Series multimeter comes in a rugged protective holster, with a unique "Flex-Stand"™, which bends and holds to any shape, allowing the multimeter to be stood or hung almost anywhere. To find out just how tough a Fluke 80 Series multimeter can be ... call your local Fluke distributor today. FLUKE AND PHILIPS - THE T & M ALLIANCE PHILIPS Transmission towers carry the OCT0BER1990 99 THIS TESTER CAN PAY FOR ITSELF IN LESS THAN ONE DAY SIMM I SIP MEMORY MODULE and DRAM TESTER * All chips are tested simultaneously * Tests 64K x 8/9, 256K x 8/9, 1M x 8/9, 4M x 8/9 and 16M x 8/9 bits. * Stand alone and portable - no need for a corn puter interface * User friendly LCD interface shows clear instructions and results * Zero insertion-force sockets for fast and easy operation * AC adaptor included * Expansion slot for add on products * Current measurement terminals * Two programmable voltage sources * Automatic current limiters provide full protection for your modules * High speed 16 Bit processor generates complex test algorithms $1499 plus TAX BONUS - SINGLE CHIP ADAPTER FOR TESTING 64K x 1, 256K x 1, IM x 1, and 4M x 1 DRAM chips power cables in groups of three, one cable for each phase. But look closer and you will see that each phase consists of a bundle of four parallel cables. Each of these four cables is typically 29.4mm in diameter, of ACSR. When viewed from ground level, it is hard to realise that the distance between the four cables in the bundle is actually quite large. The bundle measures 650mm diagonally. Why is this bundled conductor arrangement used? Why not use a larger single conductor for each phase? Thereby unfolds a story, taking us back to fundamentals . The laws of nature limit all dynamic systems to a maximum of three fundamental effects. One is an energy loss, while the other two imply energy storage. In electrical installations, the energy loss mechanism is the resistance R, while the two energy storage properties involve inductance L and capacitance C. As we have already seen, the resistance of the conductors causes power loss which is dissipated as heat. The Eraring-Kemps Creek twin lines are rated at an absolute maximum continuous current of 4000A. This is limited by the allowable conductor temperature of 120°C. The resistance is determined by the total cross sectional area of all the parallel conductors but not by their physical arrangement, so has nothing to do with the bundling arrangement (except for a secondary ventilation effect). Reason for bundling PACIFIC MICROELETRONICS PTY LTD 'CENTRAL PARK' UNIT A20, 4 CENTRAL AVENUE THORNLEIGH, NSW, 2120 Telephone: Fax: (02) 481 0065 (02) 484 4460 Australian Representative FUJITSU MICROELECTRONICS PACIFIC ASIA LTD. 100 6) FUJITSU SILICON CHIP To find the reason for the bundled construction we must look to the other two fundamentals, inductance and capacitance. Keeping in mind that the inductive voltage drop is proportional to the product of current, frequency and inductance, how can we minimise this voltage drop per km? We are stuck with a fixed frequency of 50Hz, so we must make efforts to reduce the value of inductance. The inductance of a pair of phase conductors is proportional to log(d/r) where dis the distance between phases and r the radius of the This is now a very common sight in suburban streets - 11kV 3-phase lines on top and 41 5V/240V lines below to feed homes & businesses. phase conductor. For three phases and for twin lines, the equation is a little more complex but the factor log(d/r) persists. Therefore, one way to reduce line inductance is to increase the effective conductor radius, (the geometric mean radius or GMR). Effective conductor radius A bundle of many conductors physically spaced around the circumference of a circle would be an ideal way to increase apparent conductor radius r . As this would have to be done for each phase, it would be so expensive that more economical approximations must be used. Here's where cable bundling comes in. The bundle arrangement used on each phase of the Eraring-Kemps Creek lines, with four conductors held apart on 650mm-diagonal square spacers, is an approximation to a 320mm radius conductor. Hence line inductance is greatly reduced compared to a single heavier conductor. Even with the bundling of conductors, on the Eraring-Kemps Creek line, the inductive reactance is still 15 times greater than the resistance. It would be much worse if bundling were not used. Other lower voltage transmission lines can be seen with bundles of two or three cables per phase. The same principles for reducing losses still apply. Corona On a high voltage line in midspan, the only insulation is the air. Normal atmosphere breaks down and ceases to be an insulator if the voltage gradient near a conductor exceeds 30kV/cm at the peak of the sine wave. The resultant electric discharge into the air is called corona. Unfortunately, the voltage gradient tends to concentrate near each conductor, the voltage stress being approximately proportional to V/(r x log(d/r)). Here V is the voltage from phase to ground, r the conductor radius and d the spacing between phases. Because the use of bundled parallel conductors per phase effectively increases the apparent conductor radius, the voltage stress around the wires is reduced by about 30% (bundle of four compared to a single conductor). The result is much less corona discharge. Marlinised conductors Some lines in use overseas use aluminium cables with fibrous nonconducting material or air spaces interspersed between conduction strands. This simply increases the conductor radius to reduce corona. Corona discharge does result in a real power loss. Typical values in fine weather are up to 5kW/km for a line in the 600kV range using single 40mm diameter conductors per phase. During fogs and rain, this loss increases in proportion to: (a) rain intensity (mm/hr); (b) the voltage; and (c) the fifth power of the voltage gradient on raindrops adhering to the conductor underside. Typical values are 135kW per kilometre for rain at 12mm/h for single conductor lines. Bundling reduces this loss considerably as the effectively larger conductor radius r reduces the voltage gradient. Although they can be quite high, corona discharge losses are not significant economically, considering that such a line may be carrying a few gigawatts to the city at the far end. However, corona discharge, which appears as a pretty blue glow at night, is a strong source of radio frequency interference (RFI). Therefore, for the sake of nearby radio and TV reception and telephones, it is vital that step be taken to minimise corona discharge. Catenary curve Any aerial conductor hangs in the shape of a curve called a catenary. This curve is described by the Gosh function, (quite different from the segments of a circle, elipse or parabola, etc). The shape of any power line suspended from points of equal height is given by the following formula: y = (Th/w)(Cosh(wx/Th) - 1) where: y = height of any point on the conductor x = distance of that point from midspan Th = horizontal component of tension w = conductor weight per unit length. As lines heat up either from resistive power loss or hot weather (or both), they expand in length and therefore hang lower. The reverse occurs at night when the loading is least and the weather is coldest. Construction crews must allow for these effects when erecting lines. Tensioning must be governed by the ambient temperature at that moment and the expected hottest and coldest temperatures. Aerial earth High above all conductors, suspended from the highest points on towers, runs the aerial earth conductor. This lighter cable is there to protect the main conductors from lightning strikes. Acknowledgemeuts Grateful thanks to the public relations managers and staffs of the Electricity Commissions of NSW and Queensland, to ABB and to ASEA for data, photos and permission to publish. ~ On the alert, accurate and safe Fluke 80 Series multimeters come w ith a large number of "alert" functions designed to ensure safe, easy use . The "Input Alert" prevents accidental damage through wrong lead connection . An automatic power cut-off (after 30 minutes idle) extends battery life. Thi s may be overridden in 36 hour record mode. And the readouts couldn't be easier. Fluke's patented "Touch Hold "™ feature, w hen activated, ca ptures, locks and displays each measurement, yet leaves you both hands fre e to position t he probes . In t he relative mode, measurements can be made relative to your own reference point . And there's a maximum/minimu m alert, plus automati c storag e of max/min reading s. And there's much more. Why not be alert .to all the special feature s of Fluke 80 Series multimeters . . . call your local Fluke distributor today. FLUKE AN D PHILIPS - THE T & M ALLI ANCE [e PHILIPS OCT0BER1990 101 lPRODUCT SHOWCASE I to check the POST routine, making it useful for testing motherboards. All that is needed is a power supply. The Postcard can also be used in a loop function whereby the POST routine can be continually tested during the motherboard's burn-in time. The Postcard system comes with a comprehensive instruction manual. At $849, it's the solution to testing large numbers of computers or motherboards. For more information, contact Rod Irving Electronics in Melbourne or drop in at 74 Parramatta Rd, Stanmore, NSW 2048. Phone (02) 519 3134. Mains adaptor for overseas products Postcard diagnostic card Produced by Award Software of the US, this Postcard Diagnostic System is a step in the right direction of automated computer testing. Installing it is simple - it plugs into any available expansion slot. From here, the on-board 32K ROM chip can do over 30 different tests to find faults in the major computer components, including base and extended memory, serial and parallel ports, floppy and hard discs, video system, keyboard and maths co-processor. These are selected by changing the on-board switch blocks. It can also monitor the power up self-test or POST routines and check that everything is in order. The codes generated can be seen in either hex or binary form on the LED readouts provided on the board. If all is OK, the hex displays show "FF" and the system then boots up. The best thing here is that it doesn't require an operating system Compact digital count-down timer Most digital watches these days have just about everything that whistles and blinks but it's still only the more expensive ones that give you a count down timer. This unit can be programmed to count down from anything between one and 99 minutes, after which an alarm sounds for about eight seconds. And you can interrupt the timing and restart it without resetting. It's tiny measuring only 60 x 56 x 15mm 102 SILICON CHIP and comes complete with batteries, tilting bail and magnet for attaching it to the fridge. At $12.95, you can get yours at any Jaycar Electronics store. If you buy electrical goods overseas, the first thing you'll notice when you get home is that the power plug doesn't fit! Arista Electronics have a useful solution in this 2-pin mains plug adaptor. It will convert American and European made equipment to Australian conditions. However, an important point must be made. If you want to operate US clock radios using this plug adaptor, they still won't work properly because of the difference in the mains frequency [50Hz vs 60Hz overseas), unless they have an internal frequency switch. But for shavers, hair-dryers and the like, it will work well, provided you are able to change the voltage on the equipment [from 120V US to Count on them to measure up 1n more ways ■ Tandy's new laptop computer Tandy Electronics has just released its new 2800 HD Laptop Computer. Running with an 80286 processor, it is claimed to provide the ideal balance between power and portability. It features a backlit LCD screen with 640 x 400 dot resolution and has two selectable clock speeds of either 6MHz or 12MHz. The unit has 1Mb of internal memory, a built-in 20MB hard disc drive and one 3.5-inch floppy disc drive. Tandy has included a DeskMate software package as well as MS-DOS 3.3 in the hard drive. To make it totally portable, the unit has an internal sealed lead acid battery which provides two hours of continuous use. A bidirectional parallel port, socket for a 101-key keyboard, serial communications port, modem slot and a slot for an 8087 maths co-processor are also included. The whole package measures 362 x 311 x 79mm and weighs 5.7kg. The price is $4999. For further information, contact you local Tandy store. 240VAC in Australia). The adaptor is priced at $4.95 and is available from all Arista outlets. Low-cost headphone/mic set Most headphone and mic systems are fairly pricey but this · set represents good value for money for anyone who wants hands-free communication. The unit comes with a 3.5mm stereo plug for the headphones and a seperate 3.5mm mono plug for the microphone. The headset and microphone are both easily adjusted. The earpads are covered Fluke multimeters are made in the USA, to the highest standards, offering accuracy you can depend on ... and they are guaranteed for 3 years by Philips, the name you can trust. Each measurement is clearly shown on the display, so you know exactly what you're measuring ... without having to check connections or switch positions . Fluke Models 83 and 85 have bar graphs for analogue readings, while the Model 87 has a high resolution pointer. The 10-times zoom facility lets you enhance resolution. And your Fluke Multimeter comes complete with protective holster, safety leads, 9V battery and operating instructions. To find out why no other multimeter measures up to the Fluke 80 Series ... call your local Fluke distributor today. FLUKE A'ND PHILIPS- THE T & M ALLIANCE with soft foam for comfortable wearing over long periods and the microphone is fitted with a foam screen to prevent "pops". At only $29.95, they're a good buy. See them at your nearest Jaycar Electronics store. PHILIPS OCT0BER1990 103 For Features and Performance ... mory to ta hold Ii ·ode and 'splay asurements · 4 1/2 digit large LCD display Measures capacitance 200kHz frequency counter Diode and Transistor testing _ __,.,_ High-voltage insulated screwdrivers This handy screwdriver set has four flat and three Phillips head drivers with heavy red plastic insulation on the handles and shafts. They are rated to 1000 volts. A smaller flat-head driver has a built-in neon to indicate the presence of voltages between 150 and 500VAC. All have chrome-vanadium steel shafts. The flat-head sizes are 6 x 150mm, 5 x ·125mm, 4 x 100mm, 4 x 95mm and 2.5 x 75mm, while the three Phillips sizes are 6 x 150mm (No.2), 4 x 100mm (No.1) and 2.5 x 75mm (No.0). Priced at $19.95, they are good value from any Jaycar Electronics store or by mail order from PO Box 185, Concord 2137. Phone (02) 747 1888. 3 1/2/digit large LCD display Measures capacitance Measures Temperature -20 to +15/J>C 31/2 digit LCD display Memory mode tor relative measurements Data hold function Slim,compact construction --~ Supported & Serviced Australia-wide by Elmeasco Instruments Pty Ltd N SW (02) 736 2888 Vic (03) 879 2322 Old (07) 875 1444 S.A. (08) 344 9000 W.A. (09) 470 1855 You've Gotta Getta Goldstar from : M,I.John Pope Electrical 80 6576 N.S.W. D.G.E. Systems (049) 691625 • W.F.Dixon (049) 69 5177 • Macelec (042) 291455 • Newtek (042) 271620e Novacastrian Electronic Supply 62 1358 e Obiat Pty Ltd 698 4776 e Digitel 709 6511 e Geoff Wood 427 1676 • RRITORY J Blackwood (089) 84 4255, 52 1788 e Thew & Mccann (089) 84 4999 QUEENSLAND St Lucia Electronics 252 7466 • B.A.S. Audiotronics 844 7566 • The Electronics Shob (075) 32 3632 • Solex (Townsville)(0TT) 72 4466 • Xanthos Electrical (079) 27 8952 S,A STRALIA Force Electronics (08) 212 5505 VICTORIA G.B. Telespares 328 4301 e The Electronic Components Shop 670 6474 • Fact~$ Controls (052) 78 8222 • Mektronics 587 3888 • Truscott Electronics 723 3094 W AU THALIA Atkins Carlyle481 1233 • Leda Electronics 361 7821 PAPUA NEW GUINEA TE (P.N.G.) Pt Moresby 25 6322 Lae 42 6246 ~w "Recommended prices only Mini hifi speaker system for cars The worst thing about installing your own hifi system in your car is cutting out the holes to fit those flush mount speakers. These new car speakers from Arista do away with the need for holes in panels and have mounting brackets for quick installation. Each speaker box contains a 133mm woofer, a 45mm midrange and two 25mm tweeters. Their impedance is 40 and the frequency response is claimed to extend from 65Hz to 20kHz. The power rating is 55 watts and the dimensions are only 260(W) x 125 (deep at bottom) x 85 (deep at top) x 170mm high. The price? $229.95. Contact Arista Electronics for further information (PO Box 191, Lidcombe, NSW 2141]. Probe-style multimeter Most meters are quite bulky when it comes to having to take one out on a job but this unit is just the thing to slip into your work case or even a coat pocket! It's only 185mm long and weighs just 70 grams. It has the option of both auto or manual ranging and can measure AC and DC volts to 500V in four ranges, current to 200mA and resistance to 20MO in six ranges. It also features diode and continuity checks and Touch mouse uses finger movement has two LEDs which indicate high or low logic states. The general accuracy on volts is approximately 1 %, 1.5% for DC current and 2.5% for AC current. When testing logic levels, the unit can be powered by the logic supply via the external cable provided. The unit comes with batteries, probes and logic supply cable, plus a brief operation manual. At only $59.95, it represents pretty good value. For further details, contact Geoff Wood Electronics on (02) 428 4111. Eyeglass repair kit tronics. For more information, contact them in Sydney on (02) 519 3134 or Melbourne (03) 663 6151. External 1.2MB floppy for PS/2 systems Data transfer to and from floppies has always been restricted to 360K discs on the PS/2 system which is an increasing problem as 1.2MB discs gradually become the norm. To solve this problem, PC Marketplace is now distributing the Roctec RF572BS 1.2MB 5¼-inch 5 ¼-inch The worst thing about operating a conventional mouse is the need for clear desk space that usually doesn't exist. How many times have you lost that mouse pad under a wad of paper? This new touch-sensitive mouse from Rod Irving Electronics requires no extra space for movement and works by finger pressure on the 58 x 48mm top panel to move the cursor around the screen. It works under Microsoft's mouse operating system, can be used on IBM PC/XT/AT and compatibles, and is able to be used with all existing mouse software. The model ATM-110 is available for $149 from Rod Irving Elec- drive that not only reads and writes to 1.2MB discs, but to 360K discs as well. The drive comes with built-in software to support the 1.2MB function, which is not normally used in the PS/2 system. The price of the unit is $449 including tax and it comes with a 12-month guarantee. They are exclusively distributed by PC Marketplace. For more information, ring them on (02) 418 6711. This little kit is intended for repairing glasses but could be handy for other jobs where small screws or screwdrivers are needed, such as on cameras. The kit contains a small screwdriver, four replacement screws and two hinge rings. It comes in a :Qlastic cany case and costs $1.99 from any Jaycar Electronics store. .,.s;.;;;r..i;;.:.;;~ RCS Radio Pty Ltd is the only company which manufactures and sells every PCB [, front panel published in SILICON CHIP, ETI and EA . 651 Forest Road, Bexley, NSW 2207. Phone (02) 587 3491. OCT0BER1990 105 625V A toroid transformer 128MB memory expansion board That's not a a mistake! - 128 megabytes of memory. That's more memory than you can poke a hard disc at! The LCS-8661N expansion board allows you to fit up to 32MB per board using the new 4MB x 9 SIMM modules. PC Marketplace, distributors of the board, claim you can install a maximum of four of these boards into an AT or compatible system to give 128MB. It can operate in conventional, extended and expanded memory modes and grows as your needs demand. It also has an external power supply connection for data retention after the main computer system has been switched off. The board comes with a menudriven software package, including uitility packages for hard disc simulation of memory, printer buffer and diagnostic checking which notifies of faulty memory chips. The board is powered by a 5V ± 10% 3 amp power supply and must be the ultimate answer if you never have enough memory! The board is priced at $299 including tax and is available from PC Marketplace, PO Box 1100, Lane Cove, NSW 2066. Phone (02) 418 6711. 1Mb x 9 SIL memory modules Pacific Microelectronics are now stocking Fujitsu's 1Mb x 9 DRAM module, which has an access time of only 80ns. It consists of nine MB81C1000 1Mb chips on a 30-pin surface-inline (SIL) card, each with power supply decoupling capacitors on board for the dual + 5V supplies re- Assorted cable tie pack quired. Column access times are quoted at 25ns maximum and the fast page mode cycle time is 55ns. For price and availability, contact Pacific Microelectronics, Unit A20, 4 Central Ave, Thornleigh 2120. Phone (02) 481 0065. SOUND AUSTRALIA SOUND AUSTRALIA SOUND AUSTRALIA SOUND AUSTRALIA can offer you everything from electronic components to professional public address systems Amplifiers - 100 Watts to 1800 Watts/mixers, speakers, microphones supersoft high quality coloured microphone cable + many more electronic accessories BRING ALONG OR POST THIS AD TO RECEIVE A S5 GIFT VOUCHER Ph (03) 791 1622. 28 Walker St, Dandenong 3175 106 SILICON CHIP Need a big transformer for your next power supply? This is probably the biggest you'll get without getting one custom wound. Rated at 625VA, it has three separate 16.5 volt secondary windings, which can be tied together to give a total of 38 amps RMS. Data sheets can also be provided on request. The price of this transformer is $128.78, including sales tax. It is available only from Harbuch Electronics Pty Ltd, 90 George Street, Hornsby, NSW 2077. Phone (02) 476 5854. Do your projects look like the proverbial bird's nest, with very untidy wiring? Such wiring is not only hard to troubleshoot but it can be unsafe too. One solution is to tidy it up with a few plastic cable ties. That's a good reason to have one of these assorted cable tie packs. There are three sizes: 90mm x 2.4mm, 115 x 4.8mm, and 188x 4.8mm for the heavy duty jobs. Once they're on, they won't come off as they have a ratcheting grip. . For $6.95, you get a total of 75 ties in the pack. They're available from any Jaycar Electronics store. wpoD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS .. . WOOD FOR: C Weller ~ AT&M KITS Save Problems and Cost with :~~~~ MEMOREX Iron Stat,on GENUINE PREMIUM GRADE DISKS T::s:eos"W:i1~~~~r::if~~ ~~roo 0 ~~:)~~~~gi:~~~mte:\\>perature sensitive components. • 4/rN stainless steel heater • Non-burning silicon rubber cord • 15 tip sizes - 0.8mm to 6.00mm e 11secs to recover for 37°C drop 51/4 2S/2D 5 1/4 2S/HD 3 1/2 2S/2D 3 1/2 2S/HD $16.95 per 10 $24.95 per 1O $24.95 per 1O $49.95 - :og~tf1~2M~r.p:aiig7a5~1~•c, Weller WTCPS $137.00 Weller EC3001 OElectronic Controlled Solder Station $325.00 Weller EC1001 o Electronic Controlled Solder Station $195.00 Replacementllps $8.95 w, hav• a hUfl• rang, of Irons ta 1uit ,vary f81/Uiremsnt Fluke 80 Series... A//2mloni EPROM PROGRAMMING Husky EPROM Programmer • Professional PC based pro~rammer ~ tex: ?x32~~~tfEtl~Wi¥d°~~~~X& to • 1MB program In under 3minutes Husky $936.0D ex tax~, 09 plug to U915 socket (that's the triple row 15 pin in a 9 shell) 129.95 D9 socket to 025 Plug_ 19.95 D9 ~lug to 8 ~in MlnFDIN 15.00 ~B~ 8~ s~t~f t~ o~i'lx:ket ~iJ~J~e~ Socket 19.95 We have the D23 Plug to D23 ~~~~~ri~~i.!~~~~~r! $29.95 $1092.DD Our 4 way, 2melr1 adaptor. Consists of Male and Female 025 to Male and Female 025. Ideal for service technicians and Installation people. A very versatile piece of cable! . $34.00 C) LI.. Cl a lr:,y ~ Standalone with LCD display 11MHzcpu ~mr~i~:r2716to27512 32pin ZIF socket RS232 port etc Shooter ($825 .DO ex tu) $962.50 LER123 EPROM Eraser ~:r: (.) cc C) LI. Cl C) ~ • 34x28pin capacity • Double element • Variable timer LER123 ($226.95 ex tax) $263.25 $261.55 LER121 EPROM Eraser • 9x24pin capacity • 5000µW/sq cm element LER121 ($90.8D ex tax) E301 ($26 .15 ex tax) $30.D5 Loa ic Pu Iser • 0.5 to 400pps • 10µs width at 100mA load • Sync Input ELY81D ($34.60 ex tax) $39.95 04 05 06 07 08 09 10 11 12 13 14 16 17 the line! 25 4 3/4 digit 4000 count resolution 01itai Display updates 4 times/s 8ba~~J~~i~~~~rin~:S have o.sWz to 200kHz Counter with dutv cycle from 0.1 % to 99.9% • 1OpF to Sf, Capacitance range 22 23 24 Price $33.6D 4 digit Counter 5D.40 3 1/2 digit DVM 59.40 1Hz Timebase 22.40 Fibre Optic Modem 75.DD Reciprocal Calculator 29.40 10MHz Timebase 45.6D V/F Converter 42.60 FN converter 42.6D Quad Power Supply 60 .60 10 Minute Controller 46.2D 6 dig Batch Counter 75.00 3 Digit Counter 65.40 3 1/2 digit LCD DVM 42.60 10kV Isolator 70.80 Storage Adaptor 193.80 8 bit UART 66.00 6 dig Up/Dn Counter 69.60 IR Transceiver 39.60 Multi-Timebase 42.60 16Ch Tranmitter 77.40 16Ch Receiver 77.40 22/3 Comms PCB 34.80 22/3 Radio Modem 66.60 TOOLS : r,~tfterue~~l~~s Peak Min • T~~hh~ig,f:lWe~l~!s~~es 83 85 87 $478.80 $576 .00 $696 .00 ($399.0D ex) ($480 .00 ex) ($580 .00 ex) $393.60 $180.00 $288.DD Coax Stripper Suits RG58 and RG59 $41.95 ($328.00 ex) ($150.00 ex) ($240.00 ex) Coax ~-" ULTRASONIC Suits RG58 and RG59 • ~ = CLEANER 4 _ $\AH.ESS The latest high-tech Wilf to clean PCB's, switches, watches, drafting pens - even your dentures! Let the millions of tiny cavitation bubbles clean the surface 40000 times per second. 165x90x50mm container 0 " ' " ' " " ' ' " " " holds half a litre and ·is made of 304 stainless steel. Some people are charging $200. Our's are only $150 See Review In Silicon Chip Nov 89. Accommodates up to 24 14-pin ICs and has all the IBM signals brought , out to pin sockets on the board. Includes OB25 female socket tor external connections. Suits ATn<r or compatibles. $87.91 Low cost accessory tor your scope. ~~roe~kl\1ifn~~rljs~~ i:i~~i~ ; data words tor storage In 2048 word memory. Ideal for one-shot observations. Reolay as many times as you like. See description in EA December. Complete kit (AT&M17) with top quality components and full Instructions Is lust $193.80 Matching case (ATM17--01) $27.80 ~ carry case. $69.95 -" t .? 40MHz 2 Channel Scope :,:,. • ,,,. ·• / • SmV/div de to 40MHz . · '\ ·1~ _ '!iifl l ~'4-'• SCOPES ~ •\ "'t • 20ns/div to O.Ss/div Main Vi) _ • o.~ to o.sms/div Del~ed • 5mV/dlv de to 60MHz e Snsldiv lo 0.5sldiv /I and B COS5D6DB ($1593.90 ex tax) ~g~~f~:'ls great Portasol Kit. • • • • • • Pocket Sized Iron 4 Tips & Cleaning Sponge Heavy Duty Carry Case Solder Butane Gas Refill PLUS Wrist Watch Yes you can get the kit elsewhere, but who has got them at our price? Just $74.95!! But Hurry! SerialTest serial data analysis on your PC This is an MS-DOS software and cabling package which enables technicians and engineers to perform serial data comms analysis. It offers sophisticated problem solving facilities at a fraction of the cost of dedicated hardware systems. SerialTest provides a window onto RS232 lines operating either as a passive observer or actively sending ~~~~~rnwo6/Wif~e~g,:muiale Triggers can be defined based on error conditions or data to initiate or terminate monitoring sequences. • Handles baud rates up to 115.2kbaud. • View each byte In ASCII or EBCDIC, decoded to hex, decimal, binary or octal • Writes cap tu re ata Irectlv to disk to allow maximum capfure buffer • CRC checksum calculations • Auto-configuration to any of the comms ports 1 to 4 • Time-stamping (absolute and relative) including delta time calculations • Split line DTE Send $10 tor a demo tsk, refundable on purchase. fNli~sd!i~~tax 20MHz Readout Scope • Cursor measurements • SmV/div de to 20MHz • 20ns to 0.5s/div $806.40 $1372.5D GOS625 ($691.15 IX tax) ($1176 .50 ex tax) 10MHz Low Cost Scope 20MHz 2 Channel Scope .;.., 1 COS5041 60MHz 3 Channel Scope SUPER SOLDERING SPECIAL t: Hole Punch Set , . 1U~o5fore:mtyJ:m~~~~s ,~gl~des , • r tapenid reamer and rigid plastic _ Adjustable from 10-60W D-Sub Crimper ~~~eurfe~o~:&fsu~~;~e1~~~~poJ;~r plastic, aluminium etc. Simply drill 3/8' hole Ideal for square panel cut outs $19.95 1. , Built-in Flint Ughle, Assemble contacts quickly $88. Nibbling Tool AT&M Digital Storage Adaptor Kit Logic Probe • 17MHz max frequency. • 30ns detection • H1 Lo, Pulse LEDs 03 • • • • $105.30 • TTb CMOS, 24V compatible 02 21 UP604 IBM Breadboard Card QUV·T8T EPROM Eraser • 5'X8' slide out tray • Timer : !~~b~?n~ capacity OUV-T8T ($224.2D ex tax) top of 23 73 75 Shooter EPROM Programmer • • : • • K~ Oescription 01 3 digit Counter 18 19 20 Also ... l 'f'.¾d We carry the full range of the gnial kits. Wl1y develop your own ctrcu//s wf1Bn these /Jui/ding blacks are already available? • 5mV/div de to 20MHz • 20nsldlv to 0.5s/div $1859.DD COS5020 ($756 .80 ex tax) $882.90 • Compac~ single channel • SmV/div de lo 10MHz 10 0 io11i{Wv ·1µs/div $496 .65 ($425 .69 ex tax) ~0 c:, -,, 0 JJ () :r: ~ ~ ~ GEOFF WOOD ELECTRONICS PTY LTD 0 ex: 229 Burns Bay Road, (Corner Beatrice·st.) iNc IN Nsw Lane Cove West, N.S.W. P.O. Box 671, Lane Cove N .S.W. 2066 0 Telephone: (02) 428 4111 Fax: (02) 428 5198. () ~ C) LI.. Cl C) ~ 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. Pri_ces shown in brackets are sales tax exempt Tax exemption certificates accepted if line value exceeds $10.00. BANKCARD, MASTERCARD, VISA, CHEQUES OR CASH CHEERFULLY ACCEPTED c:, -,, JJ :r: ~ Silicon Chip BACK COPIES February 1988: 200 Watt Stereo Power Amplifier; Deluxe Car Bur lar Alarm; End Of File Indicator 11i.i. Low Ohms Adaptor Isolation Unit For Pho ~ ips On Headphone Repair. i'di..'-01_i8~ne March 1988: Remote Switch For Car Alarms; Telephone Line Grabber; Endless Loop Tape Player; Build Your Own Light Box; New Life For Radio-Cassette Players; Old-Time Crystal Radio. April 1988: Walkaround Throttle For Model Railroads, Pt. 1 ; pH Meter For Swimming Pools; Slave Flash Trigger; Headphone Amplifier For CD Players ; What Is Negative Feedback, Pt. 1 ; Mobile Antennas For The VHF & UHF Bands. May 1988: Optical Tachometer For Aeromodellers; High Energy Ignition For Cars; Ultrasonic Car Burglar Alarm; Walkaround Throttle For Model Railroads , Pt.2; Designing & Building RF Attenuators; Motorola MC3334P High Energy Ignition IC Data. June 1988: St (Uses LM8 ,v_:~.i,.-~r_..,amplifier ss Ignition For Cars U~~=;;:;~~;.':""';~ ups; MegaFast Nicad tomatic Light Controller (Uses PIR Detector); RF Sniffer Probe & Preamplifier; What Is Negative Feedback, Pt.2. July 1988: Stereo Control Preamplifier, Pt.2; Fitting A Fuel Cut-Off Solenoid; Booster For TV & FM Signals; The Discolight Light Show, Pt.1; Tone Burst Source For Amplifier Headroom Testing; National Semiconductor LM833 Op Amp Data; What Is Negative Feedback, Pt.3 . August 1988: Building A Plasma Display; Universal Power Supply Board; Remote Chime/Doorbell; High Performance AC Millivoltmeter, Pt. 1; Discolight Light Show, Pt.2; Getting The Most Out Of Nicad Batteries; Data On Insulated Tab Triacs. September 1988: Hands-Free Speakerphone; Electronic Fish Bite Detector; High Performance AC Millivoltmeter, Pt.2; Vader Voice; Motorola MC34018 Speakerphone IC Data; National Semiconductor LM 1 2 1 50W Op Amp Data & Applications; What Is Negative Feedback, Pt.4. October 1988: Stereo FM Transmitter (Uses Rohm BA 1 404); High Performance FM Antenna; Matchbox Crystal Set; Electronic House Number; Converting A CB Radio To The 28MHz Band ; Oueensland 's Powerful Electric Locomotives. November 1988: 120W PA Amplifier Module (Uses Mosfets); Poor Man 's Plasma Display; Automotive Night Safety Light; Adding A Headset To The Speakerphone; How To Quieten The Fan In Your Computer; Screws & Screwdrivers, What You Need To Know ; Diesel Electric Locomotives. December 1988: 1 20W PA Amplifier (With Balanced Inputs). Pt.1 ; Diesel Sound Generator; Car Antenna/ Demister Adaptor; SSB Adaptor For Shortwave Receivers; Electronics & Holden's New V6 Engine; Why Diesel Electrics Killed Off Steam; Index to Volume 1. January 1989: Line Filter For Computers ; Ultrasonic Proximity Detector For Cars; Simple Computer Sound Repeater; 1 20W PA Amplifier (With Balanced Inputs) Pt.1; Use this handy form to order your back copies "II\ · I I I I I I I II I I I I I I I I I - Please send me D May 1 988 D October 1988 D March 1 989 D August 1989 D January 1990 D June 1990 --------------------------- a back issue for: D June 1 988 D No\;'ember 1988 D April 1989 D September 1 989 D February 1990 D July 1 990 □ February 1 988 D July 1 988 D December 1988 D May 1989 D October 1989 D March 1990 D August 1990 D D D 0 D D March 1 988 August 1 988 January 1 989 June 1989 November 1989 April 1 990 □ September 1990 D D D D D D •--7 April 1 988 September February 1 989 July 1989 December 1989 May 1990 Enclosed is my cheque/money order for $ ______ or please debit my ~ ~~~~ir~~rd D Visa Card Card No. I II ]I II Signature _ _ _ _ _ _ _ _ _ _ _ _ Card expiry date._ ~ ~ Name _________________________ SE PRINT) (PLEA Stree._____________________ Suburb/town, _ _ _ _ _ _ _ _ _ _ _ _ Postcode._ _ _ _ Price: $A5.00 each (includes postage). Overseas orders add $A1 .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 OR FAX: (02) 979 6503 X I ~------------------------------------~108 SILICON CHIP How To Service Car Cassette Players; Massive Diesel Electrics In The USA. February 1989: Transistor Beta Tester; Minstrel 2-30 Loudspeaker System; LED Flasher For Model Railways (uses LM3909) ; Build A Simple VHF FM Monitor (uses MC3362) , Pt.1; Lightning & Electronic Appliances; Using Comparators to Detect & Measure. March 1989: LED Message Board, Pt.1 ; 32-Band Graphic Equaliser, Pt.1; Stereo Compressor For CD Players; Map Reader For Trip Calculations; Amateur VHF FM Monitor, Pt.2; Signetics NE572 Compandor IC Data; Electronics For Everyone Resistors. April 1989: Auxiliary Brake Light Flasher; Electronics For Everyone: What You Need to Know About Capacitors ; Telephone Bell Monitor/ Transmitter; 32-Band Graphic Equaliser, Pt.2; LED Message Board, Pt.2. May 1989: Electronic Pools/Lotto Selector; Synthesised Tom-Tom ; Biofeedback Monitor For Your PC; Simple Stub Filter For Suppressing TV Interference; LED Message Board , Pt.3; Electronics for Everyone - All About Electrolytic Capacitors. Ju ne 1989: Touch-Lamp Dimmer (uses Siemens SLB0586); Passive Loop Antenna For AM Radios; Universal Temperature Controller; Understanding CAO Probes; LED Message Board, Pt.3; Coherent CW A New Low Power Transmission Technique. Jul y 198 9: Exhaust Gas Monitor (Uses TGS81 2 Gas Sensor); Extension For The Touch-Lamp Dimmer; Experimental Mains Hum Sniffers; Compact Ultrasonic Car Alarm ; NSW 86 Class Electrics; Facts On The PhaxSwitch - Sharing Your Phone Line With A Fax Machine. Augu st 1989: Build A Baby Tower AT Computer; Studio Series 20-Band Stereo Equaliser, Pt.1; Garbage Reminder - A 7-day Programmable Timer; Introduction To Stepper Motors; GaAsFet Preamplifier For The 2-Metre Band ; Modern 3-Phase Electric Locomotives. September 1989: 2-Chip Portable AM Stereo Radio (Uses MC13024 and TX7376P) Pt.1; Alarm-Triggered Telephone Dialler; High Or Low Fluid Level Detector (uses LM1830N); Simple DTMF Encoder (uses Texas TMC5089); Studio Series 20-Band Stereo Equaliser, Pt.2; Auto-Zero Module for Audio Amplifiers (Uses LMC669); A Guide To Hard Disc Drives. October 1989: Introducing Remote Control; FM Radio Intercom For Motorbikes (Uses BA1404 And TDA7000) Pt.1; GaAsFet Preamplifier For Amateur TV; 1 Mb Printer Buffer; 2-Chip Portable AM Stereo Radio, Pt.2; Installing A Hard Disc In The PC; A Look At Australian Monorails. November 1989: Radfax Decoder For Your PC (Displays Fax, RTTY and Morse); Super Sensitive FM Bug; Build A Low Cost Analog Multimeter; FM Radio Intercom For Motorbikes, Pt.2; 2-Chip Portable AM Stereo Radio , Pt.3; Floppy Disc Drive Formats & Options; The Pilbara Iron Ore Railways. December 1989: Digital Voice Board (Records Up To Four Separate Messages, Uses Texas TMS3477NL and 256K RAMs) ; UHF Remote Switch; Balanced Input & Output Stages; National Semiconductor LM831 Low Voltage Amplifier IC Data; Install A Clock Card In Your PC; Index to Volume 2. January 1990: Service Tips For Your VCR; Speeding Up Your PC; Phone Patch For Radio Amateurs; High Quality Sine/Square Oscillator; Active Antenna Kit; The Latest On High Definition TV; Speed Controller For Ceiling Fans; Designing UHF Transmitter Stages. February 1990: 16-Channel Mixing Desk; High Quality Audio Oscillator, Pt.2; The Incredible Hot Can·aries; Random Wire Antenna Tuner For 6 Metres; Phone Patch For Radio Amateurs, Pt.2; PC Program Calculates Great Circle Bearings. March 1990: 6/ 1 2V Charger For Sealed Lead-Acid Batteries; Delay Unit For Automatic Antennas; Workout Timer For Aerobics Classes; 16-Channel Mixing Desk, Pt.2; Using The UC3906 SLA Battery Charger IC; Digital Waveform Generation Using a PC; The Controls On A Model Aircraft. April 1990: Dual Tracking ± 50V Power Supply; VOX With Delayed Audio; Relative Field Strength Meter; 16-Channel Mixing Desk, Pt.3; Simple Service Tips For Your Microwave Oven; Model Aircraft Aerodynamics; Active CW Filter For Weak Signal Reception. May 1990: Build A 4-Digit Capacitance Meter; High Energy Ignition For Cars With Reluctor Distributors; The Mozzie CW Transceiver; Waveform Generation Using A PC, Pt.3; 16-Channel Mixing Desk, Pt.4; What To Do When Your Computer Goes Bung, Pt.1 ; Electronic Load For Checking Power Supplies. June 1990: Multi-Sector Home Burglar Alarm; Low-Noise Universal Stereo Preamplifier; Load Protection Switch For Power Supplies; A Speed Alarm For Your Car; Design Factors For Model Aircraft ; Fitting A Fax Card To Your Computer; What To Do When Your Computer Goes Bung , Pt.2. July 1990: Digital Sine/Square Generator, Pt.1 (Covers 0 -500kHz); Burglar Alarm Keypad & Combination Lock; Simple Electronic Die; Low-Cost Dual Power Supply; Inside A Coal Burning Power Station; Weather Fax Frequency List; What To Do When Your Computer Goes Bung, Pt.3; Digital Waveform Generation Using A Computer, Pt.4 (PC Board Plus Software). August 1990: High Stability UHF Remote Transmitter; Universal Safety Timer For Appliances; Horace The Electronic Cricket; Digital Sine/Square Wave Generator, Pt.2 ; The Tube Vs. The Microchip (Two Shortwave Receivers Compared); What To Do When Your Computer Goes Bung , Pt.4. September 1990: Music On Hold For Your Telephone; Remote Control Extender For VCRs; Power Supply For Burglar Alarms; Low-Cost 3-Digit Counter Module; Voice Mail For Your Computer; Simple Shortwave Converter For The 2-Metre Band; How To Make Dynamark Labels. PLEASE NOTE: November 1987, December 1987 , January 1988, February 1 988 & June 1 988 are now sold out. All subsequent issues are still available but stocks of March & April 1988 are now low . Order now if you want these issues. OCT0BER 1990 109 REMOTE CONTROL By BOB YOUNG The adverse effects of dihedral on aerobatic aircraft This month, we will conclude our considerations of the design elements in modern aerobatic pattern aircraft. This is an important topic in view of the trend towards more sophisticated electronics in R/C transmitters. In addition to the six points raised in the last column on this subject, in the June issue, there is one additional and very important point. Aerobatic manoeuvres must be presented to the judges in such a manner that the model aircraft stays inside a hypothetical "box". Thus, the size of the manoeuvres is severely restricted. The ramifications of this rule are serious and, in full size aerobatics, have tended to favour the development of the biplane, of which the Pitts Special is an outstanding example. Such a trend is developing in model aviation and we are beginning to see model biplanes appearing in aerobatic events. I feel this is a real pity, for we now live in the world of fast jets which use vast amounts of sky and which perform the most graceful and sweeping of manoeuvres. To /C::::::-, -+- - ~ c ~ SIDE-MOUNTED MOTOR return to sharp, jerky manoeuvres is very dissatisfying. I would not mind much if there was a choice but as it stands at the moment, the fast sweeping model is completely locked out of the competition scene. To me, the most spectacular and difficult manoeuvre is the low slow roll, performed at high speed and stretched out in a perfectly straight line over the entire field. This is very, very graceful indeed and exhibits complete mastery over the aircraft. Neutrally stable aircraft Back now to our analysis. To begin, the best approach is the centreline, neutrally stable aircraft. Thus, the basic parameters are as follows: wing and tailplane of symmetrical section, mounted on the thrustline. Fig.1 gives a stylised version of the design to date. /7\ ==---~~s ~~ . --===---SYMMETRICAL WING SYMMETRICAL TAILPLANE Fig.1: the best approach for aerobatics is the centreline, neutrally stable aircraft. This has symmetrical wing and tailplane sections mounted on the thrustline and will go exactly where you point it. 110 SILICON CHIP At this point, it is necessary to delve further into the secondary effects of the flight controls in order to establish some very important design parameters. One of the most destabilising effects of the controls on design considerations is the secondary effect of rudder, which is a roll in the opposite direction to the yaw. Fig.2 shows the problem. The rudder in effect acts as a mini aileron. The effect is most noticeable in a slow roll, due to the very small aileron deflection called for. Application of top rudder, applied when the model is on its side in knife-edge flight to keep the nose up (Fig.2), speeds up the roll on one half of the manoeuvre and slows it down on the other. This means that some compensation must be fed into the ailerons to keep the roll rate constant. This can be a real pain. If judges spot a change in roll rate, bang go more points. Here again we see the highly interactive nature of an aircraft between all three axes - an ideal opportunity for some computerised hocus-pocus from our encoders. The modern move to mixing of control channels drew its strength from attempting to derive electronic solutions for these problems. Knife edge flight There is also plenty of scope for some aerodynamic hocus-pocus. The obvious answer to this problem is to design an aircraft that will hold knife edge flight with a minimum of top rudder, or ideally, no rudder at all. This is an impor- RUDDER ANTI-ROLL Ct=J--=======:.:.-=.:.-:.-:.-~::---4<~r-T------c::;::b AILERON ROLL COMPONENT Fig.2: application of the rudder to keep the nose up when the aircraft is on its side speeds up the roll on one half of the manoeuvre and slows it down on the other. In effect, the rudder acts as a mini aileron. tant point and we will return to it soon. Knife edge flight is straight and level flight with the wings vertical (see Fig.3). Speed is a great help in this situation as we are relying entirely upon the lift from the fuselage side area and you will recall that lift is related to velocity squared. It also suggests a fuselage with generous side area and a plan view which is like an aerofoil section. Narrow, parallel sided fuselages are out. Let me point out here that many a designer has been bewitched by the problem of secondary rudder effects, including myself. One of the many fixes tried for this problem is the application of anhedral to the tailplane (ie, sloping downwards see Fig.4). Now we really are in it up to our nostrils. The primary and secondary effects of dihedral and anhedral when combined with the weathercock stabilisation effect provided by the fin and rudder are tremendously complex. Perhaps I had better explain. Dihedral effects The series of diagrams of Fig.5 show the primary and secondary effects of anhedral and dihedral when applied to a wing. Fig.5(a) shows the traditional effect of dihedral applied to a wing in order to provide roll stabilisation. If a gust from below upsets the air- craft and lifts one wing, the aircraft will immediately begin to fall sideways [sideslip) towards the low wing, thus producing a crosswind component striking the aircraft from the side of that low wing. This also applies if we fly one wing low, another very important point which will be discussed further. This will in turn call into play the weathercock stability of the vertical stabiliser and the result is that the aircraft will turn into this crosswind and thereby increase the deviation from the original flight path. This will ultimately lead to an ever increasing deviation and eventually a spiral dive. This is a real irony, for the better the weathercock stability, the greater the spiral instability, yet we cannot fly an aircraft without weathercock stability. As I have stated in some earlier columns, aerodynamics is one huge compromise and the balance between all of the various factors is a very delicate one. Let me tell you that there have been, and still are, good aeroplanes and bad aeroplanes. The bad ones are really dangerous to fly. How then do we get around this problem'? Fortunately, the addition of dihedral [ie, wings sloping upwards) provides a simple fix. In a side slip, which develops soon after a turn is initiated, the inside wing strikes the slipstream at a higher angle of attack than the outside wing and the aircraft rolls away from the crosswind component, thereby restoring the original flight path. This is a very important point when we come to pattern aircraft design and we will return to it shortly. Roll stability Fig.3: during knife-edge flight (ie, with the wings vertical), the aircraft relies entirely on the lift from the fuselage side area. This manoeuvre is best performed at high speed. The larger the dihedral angle, the greater the roll stability. The final tur:,ning ability and spiral stability will be a complex balance of various factors including dihedral, weathercock stability, and the power of the rudder, which in turn is a function of rudder area and angle of deflection. Now roll stability is fine in a aircraft designed to be positively stable. It is not so good in an aircraft designed to fly as straight as OCT0BER1990 111 is well earned. As stated previously, aircraft design is one great compromise. Biggest ever radio controlled model Fig.4: one approach to combatting the problem of secondary rudder effect is to use an anhedral tailplane. Another approach is to design an aircraft that will hold knife-edge flight without top rudder. an arrow and perform good slow rolls. You just simply cannot afford to have an aircraft designed for pattern flying doing its own thing and all of these factors fighting each other tend to produce an aircraft which constantly demands the pilot's attention during manoeuvres. They may fly themselves well but if you wish to deliberately disturb them, then they will fight you every inch of the way. In short, they are a pain in the neck to the aerobatic pilot. .They are, of course, a dream for the pilot on a long flight who does not wish to be constantly correcting the flight path. Dutch rolling Again too much of a good thing will produce "Dutch rolling" or excessive roll stability. The Boeing 707 suffered badly in this respect, having the twin roll stabilising effects of dihedral and sweepback, and an important autopilot function was the suppression of the Dutch roll. Here again is a prime example of electronics in action to minimise interaction between axes. There is an interesting aside here which some reader may be able to enlighten me on. I have always wondered why Boeing persevered with the low, swept wing on their jet airliners. The underslung engines called for large dihedral 112 SILICON CHIP angles as a consequence, in order to keep the outboard engines clear of the ground in a bad crosswind landing. I have seen a 707 scrape an engine on the ground (very spectacular) and the 707 has severe crosswind landing constraints imposed upon it for this reason. This dihedral, when combined with the dihedral effect of swept wings, results in excessive roll stability and thus the auto pilot fix. Flying a 707 with the autopilot unserviceable is not nice and early 707s had engines torn from the pylons in some extreme cases of Dutch rolling. The mystery is deepened when one considers that the Boeing B47, the forerunner to the 707, was a shoulder wing aircraft with anhedral. This anhedral cancels the dihedral effect of the sweep back and gives a much nicer flight characteristic, completely ellminating the Dutch roll. I find this issue an interesnng one and I have not yet had a satisfactory answer to my question. One factor does occur to me, that being the safety angle. The weight of the wing and fuel is underneath the passengers in an emergency and the solid wing spar protects them in a wheels up landing. Certainly, the Boeing airliners have a reputation for safety which In one of the most elaborate radio controlled experiments I have seen to date, NASA and the FAA combin.ed resources to produce what was known as the Controlled Impact Demonstration Flight. A full size Boeing 707/720 was crashed under radio control to test various safety features under development. One of these features was a new fuel which was believed to be much safer in a crash. At the last moment, the aircraft veered off line due to the pilot accidentally inducing a Dutch roll. As a result the experiment was somewhat flawed. The point here is that even the full size R/C operators have their share of problems and interaction between axes is one of them. To return to the world of model aviation, we can now see that an aircraft with a small dihedral angle and large fin will be directionally stable and spirally unstable. So much for the traditional approach to roll and spiral stability. By now it should be fairly obvious that the position for the neutrally stable aircraft is becoming fairly murky. All of these interactions tend to make such an aircraft an impossibility it would appear. It is also becoming obvious that the more simple the design the better. The position is compounded when we now consider knife edge flight, which is in effect only straight flight in a 'yawed position. This is an essential manoeuvre in an aerobatic aircraft, forming as it does one component of a slow roll. Now this really does set the cat amongst the pigeons. How do you make an aircraft with dihedral fly in a straight line when yawed? The answer is, of course, with great difficulty. Figs.5(b) and 5[c) show that when yawed, a model will immediately try to "weathercock" the fuselage back parallel to the direction of the airflow. At the same time, the dihedral on the wing will roll the aircraft away from the advanced wing. Thus, the aircraft banks and turns. f FL a LR t E (a) AERODYNAMIC FORCES ON A STRAIGHT WING WITH DIHEDRAL IN STRAIGHT FLIGHT LL fC) (c) STRAIGHT WING WITH ANHEORAL WR-.__ FL FL (b) STRAIGHT WING, DIHEDRAL IN YAWED OR KNIFE EDGE FLIGHT (d) STRAIGHT WING , NO DIHEDRAL , YAWED FLIGHT Fig.5: if an aircraft with dihedral wings is yawed (b), lift left (LL) will be greater than lift right (LR) & the aircraft will roll away from the advanced wing. An aircraft with anhedral wings (c) will roll in the opposite direction. If there is no dihedral (d), neither wing will lift. Interestingly enough, here we find the proof that an aircraft cannot be turned on rudder only without dihedral; it will only yaw. Fig.5(d) shows this quite clearly. If there is no dihedral, there will be no increase in lift on the advancing wing and hence no turn. Thus, if you wish to fly an aircraft such as an old-timer on rudder only, then you must have dihedral. Again, the larger the dihedral angle, the more responsive the rudder - initially! Then we run into the problem of the dihedral trying to correct the turn. Thus, we can see that a model with the correct balance of dihedral and fin/rudder area will turn beautifully on rudder only. Get this balance wrong and you will have a real pig-boat on your hands. The converse is that you cannot achieve knife edge flight with dihedral, without large control deflections to counteract the rolling effects of the dihedral. This results in a very difficult, crooked and awkward looking manoeuvre. One final word on dihedral: remember also that dihedral becomes anhedral when the aircraft is flown inverted. Thus the anhedral will try to force the model to return to the upright position, again making the pilot's task of keeping his aircraft inverted a difficult one. Finally then, after this long, drawn out analysis, we arrive at the conclusion that you apply any form of dihedral to an aerobatic aircraft at your own peril. We can now therefore add a wing with no dihedral to our list of essential parameters and stylised drawing. ~ OCT0BER1 990 113 srl ==Ill COM PUTER CABLE SllCOnductorsh,elded co mpu1e, 1nterl11cec1ble W12670 · CIC6 1-9 m 10• m 100• m W1 2672 · CIC9 1-9 m 10• m 100• m :..1v11 a sm all lortuna on tMH ··o ir1tet Import "" low prome le 90<:kets! PC B mounllng s o lder ta il. A ll ti n plated p hosph or bro n u or betryllium a nd du al wlpalo, re lia blll ly. $1.60m $1 ..50m $1.20m Cat.No. Desc ript ion 1.9 W12674 "· 1.9 m -cte12 10• m 100• m $2.SOm S2.20m S1.90m W12676 · CIC16 1-9 m 10• m 100• m $3.50m $3.20m $2.50m W12678 · C IC25 1.9 m 10• m P105SO PI0560 P10S65 P10S67 P1 0568 P10S69 P1 0570 P10572 P 10575 8 pin .. .. .$0.20 $0.18 14 pln .S0.25 $0.20 16pln .... $0.25 $0.20 18 pin ....... 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CPF's filtenng capability helps eliminate troublesome and annoying interference, general hash cre.ated by small motors . fluorescent lamps. and the like that threa_ ten the performance and shorten eqwpmen1 ., 1 life of unprotected electronic components SPECIFICATIONS: Elecirical rating: 220-260 volts (AC) 50Hz 1O Amp Splke/RFI Protec1ion: 4,500 amps tor 20mlsecond pulses Maximum clamping voltage: 275V differential mode Cat.X10088 $69.95 AS232 BREAK OUT BOX A simple way of monitonng RS232 interlace lead ac11v1ty Interlace powered. pocket size tor circuit testing. morntonng and patching 10 signal power_ e d LED's and 2 spares . 24 switches enable:5 you to break out circuits or reconfigure an::! patch any or all the 24 active positions SPECIFICATIONS: Connectors: 0825 plug on 80mm ribbon cable and 0825 socket Indicators: Tricolour LED·s for TD . AD. RTS. CTS. DSR . CD. TC. AC. DTA. (EJTC Jumper Wires: 20 tinned end pieces Power: Interlace power Enclosure: Black . high Impacl plastic. Dimensions: 85 x 95 x 30mm X15700 g ... $19.95 Surges and spikes ~re caused not onl_y by lightnmg strikes and load sw1tchmg but also by other equipment being switched on and off. such as fluorescent lights. electr!c motors . frid ge freezers . air conditioners. etc For eftecttve protection such spikes must be stopped before they reach your eguipment. Simply plu~ The Button mto an outlet and 11 will protect all equipment plugged into adjacent outlets on the same branch circuit The 8utt~n employs unique met_a1 oxide vanster technology and will dissipate 150 JOUies of electrical energy (nearly twice that of comparable surge arresters l SPECIFICATIONS: Voltage . 240V Nominal Total Energy Rating 150 Joules Response Time : 1Ons Protection level 350V peak $36.95 . RIBBONS ·. .. COMPUTER PAPER Qualily paper at a low price! 2.000 sheets ol 70 gsm bond paper Cat.C21003 11 x9 112·· Cal. C21005 15 x 11 '" $67.95 $41.00 ~~ ~ / KEYBOARD . ENCLOSED PRINTER s ·1~ND EXTENSION LEAD • Keeps your paper and print-outs neal and orderly • Transparenl cove, makes!! easy to check on paper supply • Paper can be fed from lhe centre or the rear according to the design ol the pnnter • Removable drawer which allows paper to be changed w1!hout moving the printer • Retractable rear basket makes pnnt-out collection last and convernen! • Suitable for most printers THE BUTTON SPIKE PROTECTOR 5 Pin Din plug and socket PRINTER RIBBONS TO SUIT: • CPBO, SXBO, DPSO, BX100. BX100. MB100 1-9 C22036 .. $19.95 10+ 2 r;i:~e~a~~:~~~r20 only 4 WAY Cat X19 125 only $39 $49 2&4WAY CENTAONICS DATA TRANSFER SWITCHES Save time and nassles of constantly changing cables and leads around with these inexpensive data trans fer switches. These data switches support the 36 pin centronic interlace used t;ly Centromcs . Printronics. Data Products . Epson . Microrncs . 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LX800 1-9 10+ C22031....$16.95 $15.25 • MX100, FX100, RX100,L01000 P19038 ................... $1.95 1-9 10+ C22002 .... $19.95 $17.95 • LXBO 1-9 C22003 .. $12.95 10+ $11.95 • C ITOH 8510-1550 1-9 $69.95 If you have two or four compatible devices that need to share a third or fifth, then these Inexpensive data l ransfer swtlches will save you the time and hassle of constanUy changing cables and leads around • No power required • Speed and code transparent • Two/Four position rotary switch on front panel • Th ree /Five interlace connections on rear panel • Switch comes standard with C22051 .. $13.95 10+ $12.50 Erase your EPROMs quickly and. safely. This unit is the cost effective solution to your problems. It will erase up to 9 x 24 pin devices in complete safety, in about 40 minutes (less time tor less chips) • Chip drawer has 'conductive foam pad • Mains powered , High UV intensity at chip surface ensures EPROMs are thoroughly erased Without timer X14950 ..... ........ ...... $129 With built-in timer X14955 ........ ...... .. ... $159 DUST COVERS DELUXE PAINTER STAN D 9 PIN TO 25 PIN CONNECTOR ADAPTORS NEW 1 The ideal solut,on • Features gold plated pins X 15668 089 Plug lo 0825 Sockel X 15669 089 Socket to 0825 Plug each $8.95 • Aeslores order to your work area wIlhout occupying extra space • C:eeds and retolds paper under the pnn1er aulomaucally • AdJustabte paper delleclors ensure smooth flow o1 paper • Made al moulded plastic • Suitable for most prm1ers C21058 (80 columnI $69.95 NATIONAL PANASONIC KXM110 PRINTER RIBBON C22034 ..................$19.95 •Dimensions: 280 x 260 x 25mm - POCKET AUTO AB SWITCHES • Pocket size, auto-scanning • Allows 2 PCs to share one Printer Serial model: MS-201 - Host-powered X19150 ..................$79.95 Parellel model: MP-201 Protocol transparent X19155 ................•. $89.95 XT• Cover Set C21066 ..................$14.95 AT• Cover Set C21068 .................. $16.95 VGA 1MEG ......... $495 VOICE MAIL. .................. $245 PRINTER CARD.............. S35 EGA CARD ...................... $139 2 WAY Fc;D CONT. (360K) .............................. S49 RS232 SERIAU CARD ..... ......................... $49 P19045 S99.95 3½" FLOPPY DISK DRIVE EXTENSION CABLE • ISM· compatible • D837 Male to 34 IDC connector • length 0 ·5 metres P19046 S99.95 6 PROTECTED POWER OtJnETS ldeol tor protecting personal SPECIFICATIONS: • Electrical rating: 240V AC, 50Hz, 10A • 3 x M■tal Oxide V■ri1tors (MOV) • Maximum clamping lloltage: MCh UOV: 710 votts at 50 amps Remove ugly paper feed edge! quickly and cleanly with this slmpte lltlle gadget . - - - •-: Leu lhan 25 C21085 .................. $14.95 NanoNconda. X10086.....................$69.95 XT-10M M l ' " ~ - - XT 31M.......... _ _ _ _.. 1ff XT 12M STD. SIZE............. S19t SUNTEC AT 12M. ............... $375 80386-25... .!$.,.~!!J. .... $2,695 80386- 33•••!.'!l~.•.. ~~ RODIRVING ELECTRONICS SYDNEY : 74 Parramatta Rd . 2048. Stanmore. Phone (02) 519 3134 Fax (02) 5193868 AS232 MINI TESTER • Male to !emale connec!Ions • All pin w1red stra1gh1 lhrough • Dual colour LED 1nd1cates act1v1ty and direction on 7 Imes • No battenes or power requi red T D Transmit Data D S A Data Set Ready A D Receive Data C D Carner Detect R T S Request to Send D TA Data Terminal Ready C T S Clear to Send C al x 15656 Normally $39.95 a COPYHOLDE7. (YU-H32) MELBOURNE: 48 A·secken SI Phone (03) 663 6151 NORTHCOTE : 425 High SI Phone (03) 489 8866 CLAYTON : 56 Renver Rd . Phone (03) 543 7877 MAIL ORDER& CORRESPONDENCE : PO Box 620. CLAYTON 3168 Order Holl1ne 008 33 5757 {Toll free . strictly orders only) Inquiries : (03) 543 7877 Telex: AA 151938 Fax: (03) 543 2648 MICRODOT 1n SPRtNGVALE ROAD NUNAWADING. I'll.IN 1255 GREENSBOROUGH COMPUTERS 17 GRIMSHAW ST (cnr Howard ot) Ph, 4341111 BRISBANE DEALER VRC COMPUTER SERVICE M7 LUTWYCHE RD LUTWYCHE. 4030 • Adjustebte arms allows e ■ sy positioning • Copy ■ re■ 9 112" x 11" ADELAIDE DEALEl't • Slldlng line guide LEADS .. CROTROIICS • Clamp mounting 305 MORPHETT ST ADELAIDE. 5000 C21062 ........... $39.95 All sales tax exempt ordefa and -sale inquiries to: RITRONICS WHOLESALE PRINTER LEAD RIPPER STRIPPER MOTHERBOARDS (360-1.(4M) ..................... :$129 2 WAY FDD CONT. (3G0·1.<4M) ..................... $80 CLOCK CARD ................. $49 SMART DRIVE ADAPTER IDE/FDC .......... $89 SMART DRIVE ADAPTER IDE 1/0 /FDC ... $119 56 •1.8 metres P19029 ..•.•.............$14.95 • 3 metres P19030 ..................$19.95 • 10 metres P19034 ............... ... $39.95 Renver Road. Clayton Phone : (03) 543 2166 (3 Imes) Fax : (03) 543 2648 • Sults•JBM" PCIXT, compatibles • 25 pin "O" plug (computer end) to Centronlcs 36 pin pluq computers, vkleo equipment, colour TVs, arnpltflerl, tuners, graphic equallMrs, CD players etc AS232 GENDER CHANGERS • Saves modifying or replacing non.matmg RS232 cables • All 25 pins wired straight through Cat X 15650 Male to Male Cat X 15651 Male to Female Cat X 15652 Female to Female GAMES............................ $29 AT S/P GA MES............... $35 4 WAY FOO CONT. SURGE BUSTER • IBM" compatible • 0B37 Male to 34 way edge connector • length 0-5 metres CENTRONICS GENDER CHANGERS • Female to Female . • Saves_moditying or replacmg non-maltng Centronics cables. • All 36 pms wired straight through Cat . X15663M■ letoMale . Cat. X 15661 Male to Female 4 PORT SERIAL .............. $89 VGA256K. ...................... $1H VGA 512K....................... $299 Keep your computer and accessories free of dust and grime while not in use A wortcing bench for your Mouse. •High quality ABS plastic ■ nd •St ■tion■ ry holder XT HO CONTROLLER $129 AT HO CONTROLLER $199 RS232/ SERIAU CLOCK .......................... $59 MONO/ COLOUR CARD i96 MULTll/0 ....................... $99 512K RAM...................... $59 OIAGNOSTIC ................. $11411 TTU PRINTER ................$89 RAM 2M AT EXTIEXP .. $225 SM AT EXT/EXP ........... $325 FAX CARD .................. $595 DUST COVER MAGIC STAGE •Includes pull-out sheH tor Mouoe -, ,.,,.,,.' -I-Iii ,....,,, ,r,. SPECIAL. ONLY $32.95 ~-~-;~J\ anli• ■ l■ tlc rubberised top :---- . I~ For poetage r ■ tee refer to other R.I.E adverti,ement Errors and omissions excepted. Prices and specihcalions subjecl 10 COPY HOLDER • Copy acene;H,3,~) • Sliding hne guide • Flat metal base C21060 .. ............ . $39.95 change IBM. PC· J(T" AT" arereg,ste,edtr.......,..,_sot In1em111onel BuSll'IHS ~ ·AclPe ,s I ,191tered trldemert< ·Denotes reg,st.red 1r,dme,'ks ot lher, rtH(le<:!1ve ownet'$ ASK SIUCON 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. Connecting speakers in parallel I was given a heap of speakers, all 8-ohm impedance and of various sizes. I built two cabinets, each with three woofers of either 10 or 12-inch diameter and with piezoelectric tweeters. The speakers are rated at 35 watts each and I intend to drive them with the Studio 200 stereo amplifier, as described in SILICON CHIP. Before I hook them up I would like to know how, if it is possible, and if I need speakers with bigger ratings. Can you help me on this matter? These speakers are hopefully to be used in our local theatre company when putting on plays, etc. As I am a member of a theatre company, I am always setting up stage, sound, lighting and cameras. There are four members who have a video camera each and we always record our functions. This is the basis of my second enquiry. On the market (in kit form) are various audio mixers but I have never come across circuits or kits Digital storage for an Amiga I am thinking of buying a digital storage adaptor for my Amiga 500 computer. This will cost me considerably less than a CRO or for that matter a digital CRO, and also has excellent specifications (much better than some CROs I have seen) except for the bandwidth which is a measly 1MHz. I was therefore wondering if it is possible to have something like the 10:1 probe except that this would work on bandwidth instead of voltage. I could then have an input of say 50MHz which would be converted down 116 SILICON CHIP for video mixing. I wish to be able to fade in/out from up to three VCRs/cameras, and also to cut/fade the audio out of these units. I also want to add music or voice inputs from CD or tape, plus a mic input all this to be routed to a receiving VCR. The end product would be able to select from three different cameras and four different audio sources, with microphone overlay for your own voice. (A. C., Groote Eylandt, NT). problem with the idea is that you would need to have a Genlock circuit so that all the video sources are synchronised. All video sources need to be synchronised otherwise the picture would lose sync as you faded from one video source to another. A further problem with the idea is that, while most video cameras have facilities for an external sync source, most VCRs and camcorders don't. • As far as your 8-ohm speakers are concerned, it is not a good idea to connect them all in parallel since they will then present a load of less than 3 ohms to the amplifier. It would be better if you could match the units so that you have two 8-ohm speakers in parallel in each enclosure. The fact that they would then have a total rating of 75 watts would mean that they would be quite usable with the Studio 200 amplifier. As far as the video mixing situation is concerned, it is a wonderful idea and one that we are sure many people would be interested in. The Ignition killer is not a problem to a 1MHz bandwidth and I would then multiply this by the factor it was divided by to get the actual frequency. The ability to select ratios (eg, 10:1, 20:1, 30:1, etc) would be even better. The other thing that I hope that you will be able to tell me is where I might be able to find spare parts for an Akai CS-705D cassette deck (very old deck). The parts I need are the record/play head model number HN 42549N, the erase head model number 168-36 and, if possible, a schematic diagram. (T. Ingrisano, PO Box 312, Matraville, NSW 3036). • The reason the bandwidth of your proposed purchase is only I'm writing in response to P. J.' s question in Ask SILICON CHIP in August about installing an ignition killer in his VC Commodore. I've got a VC Commodore with an ignition killer installed in it, and it has been there for some time now. It was from Dick Smith Electronics (Cat K-3255). I ran the wire to the killer circuit through the plastic tube that the wires from the coil to the electronic ignition go through, then through the slit loom tubing with the rest of 1MHz is that it is limited by the analog to digital converter used. No doubt the designers could have gone for a much faster ADC but that would then have been very much more expensive. Unfortunately, it is not possible to use the frequency division process that you propose to make your storage adaptor work. Even if you got a display it would not mean anything, particularly on sinusoidal waveforms. We don't know where you can purchase spare parts for your Akai deck but we have published your name and address in the hope that one of our readers may be able to help you with this information. the car's wiring. That made it look like there is no extra wiring. (0. M., Liverpool, NSW). Amplifier aversion to black holes Mayday, Mayday. I am badly in need of a circuit diagram for my hifi amp as parts of it won't allow me to listen to music (it does not like black things with the holes in the middle). It is a "Linear Design SA8200" which is made in Japan [where else?). I've tried a few places in Melbourne but nobody has heard of them [same old story). Would appreciate help. Ta. [Shane Bearham, 140 Anzac Ave, Seymour, Vic 3660). Cassette deck is not a project Is there any chance of SILICON CHIP designing a tape deck/logic controlled cassette deck? In the past, in electronic magazines such as yours, they have had amplifiers and tuners to build but there's never been any cassette deck. Secondly, about a year and a half ago I bought a Voxson VH-777 hifi system. This model had a built in tape deck, tuner, amplifier and separate turntable (Voxson TT444). It also included 100-watt honeycomb speakers. I had a lot of trouble with the head alignment when I first got it. I also noticed that if I set the volume to less than a quarter of the way up and then pushed Stop, Rewind, Fast Forward or Play, I get this massive thump from the speakers and head~ phones. It's even worse when I push Stop during recording. I would appreciate it if you could tell me what the fault could be and how I could correct it. Other than that, I'm more than happy with it. [P. L., Kidman Park, SA). · • A stereo cassette deck was featured in an Australian electronics magazine about 16 years ago but it was a spartan unit compared to today's decks. The reason cassette decks have not been described in SILICON CHIP is simply that they would be too expensive to build, relative to the price of commercial units. There is also the pro- Bigger controller for a bigger loco I would like information on adapting your model train controller (April & May 1988) so that it may be used for the larger scales of model locomotives. Specifically, we need a higher average voltage at about the same current. The voltage envisaged is about 18 volts with the current being 4A or slightly less. We would also like the short circuit detector to not reduce the power at all until the overload setting is reached, then it should react as quickly as possible to save the motor blocks/controller. The maximum voltage allowed by the makers of our equipment is 22 volts for short periods. [How long a short period is, is not specified!) We are members of the Western Australian Garden Railways Association and we run mainly LGB, Bachmann and live steam models in our gardens. blem of obtaining an acceptable commercial finish for all the hardware, not to mention the problem of licencing for Dolby noise reduction. The thump that comes from the speakers in your Voxson hifi system is probably due to a power supply problem. This may be because of the changing current drain from the power supply when solenoids are energised or when motors start and stop. Possibly, there is a partial failure in the supply regulation circuitry or one or more of the filter capacitors has become defective. We note that you have sent in a circuit diagram. The first step in solving the problem would be to check the supply voltages shown on it and see if they change at all when you operate the deck controls. If you are desperate and can't find the cause, a simple way to improve the situation may be to connect an extra filter capacitor across the main supply rails. You can try 2200µF as a start. Make sure that the capacitor voltage rating is higher than the actual supply voltage. Sound effect modules for steam, bells and diesel that could fit (usually we have plenty of room for a small PCB) inside a tender or loco would be much appreciated. Maybe they can form a later series of projects. Although I am not a subscriber, I enjoy your magazine greatly. My only complaint is that the glossy paper can make reading the magazine in bright light painful. (R. P., Armadale, WA). • It is possible to increase the maximum voltage output of the circuit by increasing the transformer voltage so that the output from the bridge rectifier is about 25 volts DC. No other changes should be necessary. The unit is presently rated to give an output of 4A and it should not be necessary to increase the heatsinking for the output transistors. It may be necessary to reduce the 100k0 resistor in series with trimpot VR1 in order to get the maximum 18 volts output that you require. Power supply blows regulators I am currently working on a project where I have built a lOOW amplifier into the chassis and case of an old guitar amplifier. I am feeding a split power supply to a regulator circuit based on circuits in the back of the 1989 Dick Smith catalog. The input voltage to the regulators (7815 and 7915) is 70V and their outputs have been jacked up to 33V with two 8600 resistors. This then drives MJ15003 and MJ15004 power transistors to boost the output current capability of the supply. I have had the regulators working but the 7915 regulator chip has blown three times now. The 7815 continues to work fine. Could unplugging the power cord with the amplifier working just below clipping into a dummy load do this damage? If so, why only the 7915 and not the 7815? Any help with this complex situacontinued next page OCT0BER1990 117 Ask Silicon Chip - continued tion will be greatly appreciated. (D. H., Manunda, Qld). • The reason you are blowing the regulators is that you are greatly exceeding their 40 volt input/output differential. That means that the difference between the input and output voltages of the regulator should never exceed 40 volts. When you first apply power to any regulator, its output voltage will be zero and therefore the full 70 volts appears across the regulating devices. Result: zappo. The reason that you have blown the 7915 and not the 7815 is that the 7815 is usually a little more rugged but by rights, both devices are being overworked. Frankly, we don't think electronically regulated supply rails for power amplifiers are necessary or desirable. It is better to design the amplifier to withstand the normal variation in supply rails - you actually get more power and the amplifier performs better too. Modern power amplifiers with differential input stages are quite impervious to hum and supply rail variations, so why use electronic regulation? it's just another source of unreliability. However, having totally rubbished the idea of regulation, if you still must do it let's have a look at the possibilities. With an input voltage of 70 volts to the regulators, you really are asking a lot. Even high voltage regulators such as the LM317HV and LM337HV made by National Semiconductor would be in trouble since they are only rated for an input/output differential of 50V. One possibility is to use a switching pre-regulator scheme such as featured in the ± 50V Dual Tracking Supply in the March issue of SILICON CHIP. However, this would have to be substantially upgraded to deliver 2.5 amps. No really, there just ain't any easy way. We'd say you have two ways to go: (1). Dice the existing transformer for one which will deliver output voltages which can be fed directly by your proposed amplifier circuit; (2). Use an amplifier circuit which can cope with supply rails of ± 70 volts. That means using a Mosfet circuit with output devices rated at 200 volts (to give a reasonable safety margin). [§:;I Notes & Errata 3-Digit Counter, September 1990: the three transistors are shown on the parts list as BC328 but on the circuit diagram as BC558s. Both types will work but the BC328s are preferable since they have a lower saturation voltage, giving more consistent brightness in the three displays. Radfax Decoder, November 1989: the lO0µF capacitor is shown with reversed polarity on the overlay diagram. VOX With Delay, April 1990: there are three errors on the overlay diagram. First, the 47kQ resistor shown connected to VR2 should be 4.7k0, as shown on the circuit. Second, the lO0µF capacitor located just below IC3 should be a 47 µF capacitor although this value is not critical. Finally, the 47 µF capacitor located just above IC4 should be a 4.7µF capacitor. 0-lOOV 1.5A Dual Tracking Power Supply, April 1990: there is an error on the wiring diagram on page 55. The lines to points C and D on the PC board should be swapped over. As depicted, the polarity of the output terminals, and the two associated 470µF capacitors, will be reversed. Also the 0V output terminal is not connected to 0V on the PCB. It should connect to the 0V PC stake on the PCB near the lO00µF 118 SILICON CHIP electrolytic capacitors. In addition, the diode next to Dl 1 on the PCB should be marked D13 and the two 1.2k0 resistors in series with the ADJ terminal of the LM337T should be 0.5W, as specified in the parts list. In the parts list, the 0.8mm enamelled copper wire for the four inductors, L1 to 14, should be 0.5mm, as referred to in the text and circuit diagram. 16-Channel Mixing Desk, February, March & April 1990: on the preamplifier overlay diagram (April, p73}, IC5 is incorrectly shown as a 555 rather than a 7555. The lower 6.8k0 resistor connected to pin 2 of IC6 on the effects overlay (April, p78} should be a 2.ZkO resistor as shown on the circuit (March, p63}. The circuit for the equaliser/VU display (March, p66} shows a lµF capacitor from the wiper of the master fader VR13, while a 4.7µF capacitor is shown on the overlay (April, p73}. Either value is satisfactory although lµF is specified in the parts list. On the same circuit (but p67} are shown two lOµF capacitors at the 5V rail near LEDl. Only one is used, as shown on the overlay diagram. Also the lOµF capacitor at pin 4 of IC18 on page 67 is not used. Therefore, two l0µF 16VW capac- itors can be omitted from the parts list. Also on the same circuit, a lkQ resistor is shown at pin 6 of IC16 but a 3.9k0 resistor is shown on the overlay diagram. Either value is satisfactory here although lkn is the value specified in the parts list. Still on the same circuit, a 10k0 resistor is correctly shown between pin 7 of IC9b and pin 5 of IC10b. However, the PCB has the resistor connected from pin 7 of IC9b to the cut side of the frequency control pots. To correct the problem, remove the l0kQ resistor and connect it beneath the PCB between the 33pF capacitor at pin 5 of IC10c and the 220pF capacitor at pin 7 of IC9b. In the text on testing the preamplifier (April, p80}, the output of IC3b will not be at 0V as stated but close to + 15V or - 15V, depending upon the setting of TRIMl. Finally, there is an error involving the procedure for connecting a link between PC pins marked "X" on the diagram of Fig.6 (see text, April, p80}. The left hand "X" is correctly shown at the top of the PCB on Fig.6 (p73} but the right hand "X" is incorrect. It should be shown located one pad to the left so that it connects to the 5600 and 1.8k0 parallel resistor combination. CENIRF. 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 plus 40 cents for each additional word; Display ads (casual rate) - $20 per column centimetre (max. 10cm). Closing date: five weeks prior to month of sale. If you use a PO Bo x number, you must include your permanent address and phone number for our files . We cannot accept ads submitted without th is information. To run your own classified ad , put or.e word on each of the lines below and send this form with you r payment to Silicon Chip Classifieds , PO Box 139, Collaroy Beach, NSW 2097. 2 3 4 5 6 7 8 9 10 11 12 13 14 15 ($7 00) 16 ($740) 17 ($7 80) 18 ($8 20) 19 ($8 60) 20 ($9 00) 23 ($10 20) 24 ($10 60) 25 ($11 00) 22 ($9 80) Name. · · ••· ••· · ··· · ·· · · · · ·· ·· ·•· •·•· Street ·· ······ ····· ······· •· · ··· ····· ········· ·· ··· ····· ···•" ' .. .... ........... ..... ... Postcode Suburb/Town Enclosed is my cheque or money order tor$ .... D Bankcard D Visa Card D . . . . . . . .. .. . .. . . . . . . or please debit my MasterCard Signature .... Card expiry date ..... .J . . FAX THIS COUPON WITH YOUR CRFDIT CARD DETAILS TO (02) 979 . 6503 BWD DUAL TRACE Model 830 oscilloscope with probes. Good condition. $950.00. Phone (02) 602 2408 (business hours). GOLD COAST TV & VIDEO business for sale . Phone Mark: (075) 91 6445 or AH 94 6105. WEATHER FAX programs for IBM XT/ATs * * * "RADFAX2" is a high resolution, shortwave weather fax, Morse & RTTY receiving program . Needs CGA, SSB HF radio & Radfax decoder. Also "RF2HERC", "RF2EGA" & "RF2VGA", same as RADFAX2 but suitable for Hercules, EGA & VGA cards respectively. $35. From quality UK manufacturers. Available from stock at discount prices, 15VA to 625VA. Send SSAE for data & prices to: Transformer Discounters, PO Box 542, Wahroonga 2076. PLEASE PRINT EACH WORD SEPARATELY, IN BLOCK LETTERS 21 ($940) TOROID POWER TRANSFORMERS * * * "SATFAX" is a NOAA, Meteor & GMS weather satellite picture receiving program. Uses EGA & VGA modes, needs EGA or VGA colour monitor & card, plus "WEATHER FAX" PC card. $45. * * * All programs are on 5.25-inch or 3.5-inch discs (state which) & include documentation. Add $3 postage . ONLY from M. Delahunty, 42 Villiers St, New Farm, Old 4005. Phone (07) 358 2785 . MY AUSTRALIAN designed low cost super fast Z80 micro-controller development system has gained acceptance already with educational institutions. Pop it on the end of any PC MSDOS or Z80 machine and away you go. Boards, EPROM and 360K disk $76 including postage for a short form kit. Gee , I wish I had this when I was a kid. For more info . send a 41 c stamp to Don McKenzie, 29 Ellesmere Crescent, Tullamarine , 3043. KITS AVAILABLE FOR the ETI Digi1 25 $17.95 plus $2 .50 p&p. Heatsink not supplied. Kits built and repaired . Repairs to radio control equipment. Model railway projects ti _;signed and built. Prototype and production board supplier to the hobbyist . Supplier of PCBs for projects in SILICON CHIP . Electronic Toy Services (08) 382 8919 . DIGIT AL WAVEFORM GENERATION: as described in SILICON CHIP in March, May, June & July 1990. PC board and software to generate waveforms. Both for only $39.95 including p&p. Instructions included. PC Board $16.00, Software $32.50 including postage. Send cheque or money order to M. Radvanyi, PO Box 49, Kingswood, NSW, 2750. ANTIQUE RADIO ANTIQUE RADIO RESTORATIONS. Your one-stop electronic repair shop. Specialising in restoring vintage radios including chassis rewiring, quality new parts, valves, valve sockets, speakers, transformers, cabinet restoration . Quality secondhand radio dials & parts for most brands & models. About 400 radios in stock for restoration & parts. Every restored wireless is covered by a 2-year warranty on parts & service . French polishing of timber cabinets available. Vintage car radios in valve & transistor types available for restora- OCTOBER 1990 119 0 ► ..I a. a. Cl) ..1 N CD ::::, w ►~ IC') 'oi ,.._ 0 0 ~ a. C a: (,) c..o w3~ ~ ow cii a. Cl) -5 w a: £ Cl) CD (,) >< ~ CU Z LL 0 r,..~ (.) I(/) Cl C 1- en (,) ,- Ill o::r- ..1 0 • 0 c. ,c MEMORY EXPANSION 9x4MB - 120ns 1OOns 80ns 70ns 60ns 1OOns 80ns ?Ons 80ns ?Ons 8Dns 25.00 26.00 27.00 30.00 35.00 87.00 89.00 95 .00 86.00 91.00 550.00 DRAM/DIP 4164 41256 41464 4x256 1MB -1 OOns - 80ns - 80ns -80ns - 80ns 2.50 2.70 2.90 9.00 9.00 9x1MB 8x1MBMAC II) wr::1- g c5a: ..c: (I) () Cl) -~ Cl) II) a: ,- CD ~ -~ ,.._ "C CD 0 ◄ CD,.._ CD $ Cl) :I l:i :i CD :;; 0 §, = 0 ·:c a: 0. E 8: c.. 0. 0. (/) (,) 0 ::::, :::, CD SIMM & SIP 9x256 o::I' .c 0- !: 3 Cl) Advertising Index 1- (/) CO-PROCESSORS 8087-2 80287-10 80C287-12 387SX-16 387DX-16 387SX-20 387DX-20 387DX-25 387DX-33 387SX-16 387DX-2D 387DX-33 INTEL 175.00 308.00 390.00 435.0D 478.00 490 .DO 538.00 680.DO 835.00 CYRIX 400.00 490.00 75D.OO WEITEK 820 .00 1010.00 1500.00 1780.00 3167-2D 3167-33 4167-25 4167-33 Prices at August 28th T1000SE T1600 T31OOSe T31 ODSX T3200SX T3200 T5100 T5200 TOSHIBA LAPTOP 2MB 2MB 2MB 2MB 2MB 3MB 2MB 2MB 515.00 370.00 370.00 370.00 370.00 615.00 370.00 370.00 COMPAQ 386-20, 386 -25, 386-20e 386-S, 386-33 4MB MODULES 4MB BOARDS 680 .00 798.00 IBM PS/2 2MB 2MB 2MB 25D.OO 290.00 29D.DD 30/286,50 7DE61, 121 7DA21 Sales Tax 20%. Overnight delivery. Credit cards welcome. Suite 205/83 Longueville Road, Lane Cove 2066. PELHAM Tel (02) 427 0011 Fax (02) 418 6831/428 5460 ,c:-4s,-~ COPROCESSORS 2C-08 2C87-8MHz 2C-10 2C87-10MHz 2C-12 2C87-12MHz 2C-20 2C87-20MHz 2C-20H HYPERBOARD 3C-16 3C87-16MHz 3C-20 3C87-20MHz 3C-25 3C87-25MHz 3C-33 3C87-33MHz JILOA (TECHNIKIT DIV.) 'Ii "o ~{~ 476 528 618 645 130 890 915 1148 1380 Ss PO Box 73, Glenhuntly, Vic. 3163. Phone(03)571 6303. FIVE YEAR WARRANTY CAD CONNECTION PHONE (02) 957 6719 FAX (02) 954 5550 CONNECTION llnpf'oving YDUI' Pr udivity tion. Repairs done on tape decks, amplifiers, TVs & videos. Open Sat. 1Oam-5pm; Sun. 12 .30-5pm. 109 Cann St, Bass Hill, NSW 2197. Phone (02) 645 3173 BH or (02) 726 1613 ~- 120 ~ SILICON CHIP ACTIVE SHORTWAVE ANTENNA (SILICON CHIP, Jan. 1990). Complete kit $59 ; built & tested $119; case $1 O. LOOP ANTENNA. Improve signal strength & quality with this portable antenna. Kit $44; Fully built $69. FIX-A-KIT $20 PER HOUR LABOUR NO CHARGE FOR KITS THAT CAN'T BE REPAIRED 3 MONTHS WARRANTY ON REPAIRS CONSTRUCTION AVAILABLE HYCAL INSTRUMENTS DESIGN, MANUFACTURE, REPAIR OF ELECTRONIC EQUIPMENT (02) 633 5897 Adroit Electronics ... ... ..... ... 1 20 Altronics ...... .... ........ .. .... 5 7 -61 Arista .............. ... .. .. ....... .... . 20 Back Issues ............... 108,109 Board Solutions .. .......... .. 30,31 Bose Australia .......... ...... 22,23 Cad Connection .... .. .......... 120 David Reid Electronics .. .. .. IFC, 1 90,91 Dick Smith Electronics .. ..... 9-1 5 Electronic Solutions ........ 64,65 Electronics World .. .... ....... ..... 5 Elmeasco .......... .. ........ 21 , 1 04 Force Electronics ....... 110,111 Geoff Wood Electronics .... .. 107 Harbuch Electronics ........... .. 33 Hycal Instruments ........ ...... 1 20 Jaycar Electronics .. .... .... 34-37 78-81 Jiloa ............................ ..... 120 J.V. Tuners .................. .. ..... 55 Oatley Electronics ............... 69 Pacific Microelectronics ...... 1 00 PC Marketplace .................. IBC Pelham ............................ . 120 Philips .................. 99 ,100,101 Procon Technology .. ............ 55 ACS Radio .. .......... .... ....... . 1 05 Resurrection Radio .. .. .. .. .. .. .. 1 9 Rod Irving Electronics .... . 46,4 7 70,71,114,115 Silicon Chip Binders ...... .... OBC Silicon Chip Subscriptions .. ... 79 Setec Pty Ltd .. .. .. .. .. .. .. .. . .. .. . 21 Sound Australia ...... .... ....... 1 06 Subscriptions ................. 85,86 Tech-Fast .... .. .. ............... .. .. 93 Transformer Discounters .... 11 9 PC Boards Printed circuit boards for SILICON CHIP projects are made by: • Electronic Toy Services, 2/111 Glynville Drive, Hackham West, SA 5163. Phone (08) 382 8919. • Jemal Products, 5 Forge St, Welshpool, WA 6106. Phone (09) 350 5555. • Marday Services, PO Box 19-189, Avondale, Auckland , NZ. Phone 88 5730. • ACS Radio Pty Ltd, 651 Forest Rd, Bexley, NSW 2207 . Phone (02) 587 3491 . EXTERNAL DISC DRIVES COMPUTER PART# SIZE AMSTRAD D2904 AMSTRAD AMSTRAD AMSTRAD ATARI ATARI LAPTOP LAPTOP AMIGA, AMSTRAD, ATARI AND IBM COMPUTERS. BONDWELL,COMPAQ, EPSON, GOLDSTAR, PACKARD-BELL, SEMI-TECH. TOSHIBA, VERIDATA AND ZENITH LAPTOPS.TOSHIBA. COMPAQ, IBM, AND ZENITH LAPTOPS. WE HAVE AUSTRALIA'S LARGEST RANGE OF EXTERNAL DRIVES 720K FOR PC1512/1640 NEW NEW NEW 5.25" 5.25" 5.25" 360K 1.2MB 1.2MB FOR MODEL PC 2000 SERIES FOR MODEL PC 2000 SERIES FOR MODEL LAPTOP SERIES D2916 D2918 VARIOUS VARIOUS 3.5" 5.25" 5.25" 5.25" 720K 360f720K 360K 1.2MB IBM EXTERNAL DRIVES SPECIAL THIS MONTH ONLYI IBM IBM IBM IBM 3.5 3.5 5.25 5.25 720K 1.44M 360K 1.2M VALUE NOW SAVE $299.00 $329.00 $299.00 $329.00 $249.00 $299.00 $249.00 $299.00 $50.00 $30.00 $50.00 $30.00 SPECIALS CURRENT FOR MONTH OF PUBLICATION OR WHILE STOCKS - INCLUDES HARD FLOPPY CONTROLLER 42MB, 5.25, VOICECOIL, 28ms. WERE $750.00 NOW ONLY $650.00 YOU SAVE $100.001 LA-ST._. - MGACARD Monochrome Graphics Adapter for PC/XT/ AT • Text mode: 80 x 25 • Graphics mode: 720 x 348 • Compact half-<:ard • Parallel printer interlace with transfer rate up to 1000 cha.rad.en per second • Manual included WAS $109.00 NOW ONLY $79.00 NEW 32 Mb RAM CARD Suits both PC and AT type computers-Auto sense can be configured in either 521 k, 2Mb or 8Mb increments up to four boards (128Mb) per system. Conventional/Extended/Expanded memory system compatible software supplied for setupand print 269.00 329.eo- 249.00 329.00- 249.00 399.00 WITH POWER SUPPLY SWITCHABLE, WITH POWER SUPPLY SUIT TOSHIBA, COMPAQ, ZENITH SUIT TOSHIBA, COMPAQ, ZENITH NORMALLY LIMITED NUMBER HARD DRIVES PRICE COMMENTS CAPACITY 3.5" spooler and RAM disk provision for external power supply to retain data after computer is powered down. 269.00 299.00 349.00 399.00 286NEAT ~ MOTHERBOARD Emmi e 16MHz e Expandable to 1MB RAM using 256k DRAM chips or 4MB using 1MB DRAM chips• 8/12 or 8/16MHz han:!ware or Jceyboard selectable • Six 16-bit and two 8-bit expansion bus slots e AMI BIOS ROMs included e Supports all NEAT functions including shadow RAM, EMS 4.0, RAM re-mapping, selectable wait states, etc.• 80287 Math co-processor capability. NORMALLY $649.00 NOW $549.00 ATTENTIONIIII PS/2 OWNERS Until now PS/2 owners wishing to transfer data to or from 5.25" diskettes only had the choice of using 360k. Now, with the ROCTEC RF572BS drive from PC MARKETPLACE, this has changed. The drive reads and writes both 360k and 1.2Mb disks. They come with software to support the 1.2Mb function not normally used buy the PS/2. All ROCTEC DRIVES uae qualhy Japan... drive mechanlarne and feature an extremely high qualhy finish. 12 MONTH WARRANTY ON ALL DRIVES. $449.00 ONLY $299.00 ATTENTION AMIGA OWNERSI 3.5" 880K EXTERNAL FDD 512K RAM CARD 5001100012000 NOW $1 79 .00 WITH CLOCK AND EXTERNAL ON/OFF 5.25" 360/880K TRACK SWITCHABLE EXTERNAL FDD 500/1000/2000 $249.00 3.5" 880K INTERNAL KIT FOR A2000 $179.00 Pfii{ (jfeeson s $179.00 SWITCH MOUSE WITH CORD $44.95 INFRARED CORDLESS MOUSE $149.50 * 84 Key, tactile touch, switch selectable between XT/AT. ONLY 79.00 SAVE 20 PERSONAL COMPUTER MARKETPLACE PtyLtd PHONE ( -------F-RE-IG-Hr_c_HA_R_Ge-s----■-■-■-,-■-■---~ 021418 611 1 Include $10 wrth order for all normal rtems - heavy ,,.r FAX (02) 418 6713 rtems, e.g. monrtors add$15. ri->n 11, Ma ii Order Address: P.O. Box 1100 Lane Cove NSW 2066 14 day money back guarantee Order by phone {use credrt card), by fax or by mail. Unless insurance is declined rt will be charged at 1% of total purchase. This is for your protection. PRICES VALID AT 1 OCTOBER 1990 *