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• r. ING_ HI 'l ..__ -· TELEPHONE BELL MONITOR ® FLUKE AND PHILIPS - THE GLOBAL FLUKE ALLIANCE IN TEST & MEASUREMENT PHILIPS ., \) [l~~ - ¥- n ~ KE!\ ' Lfl00fQ)()0 Good as Gold Fluke Multimeters: The shining standard by which others are measured. FLUKE and PHILIPS The global alliance in TEST & MEASUREMENT announce price reductions across the entire range of Fluke multimeters and accessories. WHY SETTLE FOR LESS, When you can afford the world's best multimeters? FLUKE MULTIMETERS NOW FROM *$128.00 •(recommended retail price of Fluke 73) (ex tax) APRIL 1989 PLUG THIS SIMPLE device m parallel with your phone and it will broadcast the phone ring tone to a portable FM radio. We show you how to build it starting page 22 FEATURES 4 Electronics For Everyone by Leo Simpson Pt.2: what you need to know about capacitors 56 Fluke's New 80 Series Multimeters by Leo Simpson Measure frequency , duty cycle and capacitance 82 The Evolution of Electric Railways by Bryan Maher Pt.18: the story of Amtrak passenger services PROJECTS TO BUILD 22 Telephone Bell#Monitor Transmitter by Greg Swain Broadcasts the ring tone to your FM portable THIS FLASHER CIRCUIT is designed to flash an auxiliary brake lamp five or six times when ever the brake pedal is depressed. Build it and reduce your chances of a rear end shunt - see page 30 30 Flasher Circuit For Auxiliary Brake Lights by Bob Flynn Helps prevent rear-end shunts 36 Build a LED Message Board by Don McKenzie Pt.2: how the interface circuitry works 46 Studio Series 32-Band Equaliser by John Clarke Pt.2: how to build it & where to buy it SPECIAL COLUMNS 18 Vintage Radio by John Hill Advice to the budding collector 42 Amateur Radio by Garry Cratt The Dick Smith satellite-TV receiver 62 The Way I See It by Neville Williams What's happened to wide-screen high-definition 3D television? 70 Serviceman's Log by the original TV serviceman When VCR means Very Crook Recorder I DEPARTMENTS 2 Publisher's Letter 41 Subscription Page 80 Circuit Notebook 89 Product Showcase 92 Ask Silicon Chip 94 Notes & Errata 95 Back Issues 96 Market Centre OUR TV SERVICEMAN got all tangled up this month but eventually discovered the true meaning of "VCR" . What does it mean? - turn to page 70 _____ . _:: _:~;~::::::;::::m;~t:mm:!::£. • . _,... , BECAUSE THE PARTS are all mounted on three PCBs, our new 32-band 113-octave equaliser is easy to build. Construction starts on page 46 A PRIL 1989 1 SILICON CHIP Publisher & Editor-in-Chief Leo Simpson, B.Bus. Editor Greg Swain, B.Sc.(Hons.) Technical Staff John Clarke, B.E.(Elec.) Robert Flynn Advertising Manager Paul Buchtmann Regular Contributors Neville Williams, FIREE, VK2XV Bryan Maher, M.E. B.Sc. Jim Yalden, VK2YGY Garry Cratt, VK2YBX Jim Lawler, MTETIA John Hill David Whitby "Photography Bob Donaldson Editorial Advisory 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. Kitset suppliers may not photostat articles without written permission of the publisher. Typesetting/makeup: Magazine Printers Pty Ltd, Waterloo, NSW 2017. Printing: Masterprint Pty Ltd, Dubbo, NSW 2830. Distribution: Network Distribution Company. Subscription rate: currently $42 per year ( 12 issues) inside Australia. For overseas rates, refer to the subscription page in this issue. Liability: Devices or circuits described in SILICON CHIP may be covered by patents. SILICON CHIP disclaims any liability for the infringement of such patents by the manufacturing or selling of any such equipment. Address all mail to: Silicon Chip Publications Pty Ltd, PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 982 3935 . ISSN 1030-2662 * Recommended and maximum Australian price only. 2 SILICON CHIP PUBLISHER'S LE'I-IER Writing for SILICON CHIP One of the very gratifying aspects of producing SILICON CHIP is the way in which readers have responded so favourably. So often people write in or phone in and . offer the comment that they "love the magazine" or "look forward to it every month" or variations on that theme. At the recent Gosford Amateur Radio Club's annual field day, where we had a display, it was the same story. Lot's of people came up to congratulate us on the high standard of the magazine, how they enjoy it and so on. It gave us a real buzz. Well it is great that so many readers enjoy SILICON CHIP every month but there is a way in which you can obtain even more satisfaction from the magazine. You could contribute to the content of the magazine. Seriously. Many people do this already in the form of letters to the editor, to "Ask Silicon Chip" or to "Circuit Notebook". These letters are always welcome although recently we have had rather more to "Ask Silicon Chip" than to the editor. So if you want to write to the editor, there is plenty of space for your letter. But what about writing an article for SILICON CHIP? Or even a series of articles? We are constantly on the lookout for new material and you may well have an idea for an article that would be of great interest to our readers. It may be a new constructional project or it may be for a feature article, on almost any subject related to electronics. It could be on a theme which has not been touched upon before in SILICON CHIP but don't let that stop you. We'd like to hear from you. You don't have to be a prize-winning novelist either. All you have to be is enthusiastic and know your subject - we'll do the rest. Some of the most interesting writers in SILICON CHIP today got their start with us. If you make a small start now, you could be a well-known writer tomorrow. Nor do you have to be a skilled draughtsman - we can supply that service. So if you'd like to see your name in SILICON CHIP, contact us without delay. Alternatively, perhaps you know someone who is knowledgeable on a particular subject related to electronics. If so, why not suggest that they write for SILICON CHIP. We'd love to hear from them. Finally, while you yourself may not seriously consider writing for SILICON CHIP, you may have a number of suggestions for topics you'd like to see treated in the magazine. Send them in to us. Your suggestions can help make SILICON CHIP just that ·much brighter and more interesting. Leo Simpson FLUKE AND PHILIPS - THE GLOBAL ALLIANCE IN TEST & MEASUREMENT PHILIPS FLUKE FLUKE 87 FLUKE 73 ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ 4½ digit mode True RMS Min Max Average recording Frequency, Duty Cycle, Capacitance l000VRMS input protection Back lit display High Resolution Analog display 3 year warranty FLUKE 25 ■ ■ ■ ■ ■ ■ ■ Design~d for rugged outdoor use and (Mine Safety) Analog/digital display 0.1 % basic de accuracy 100µ,V to 1000V ac and de 0.1µ,A to l0A, all fused -15°C to 55°C operation 3 year warranty ■ ■ ■ ■ Rugged and versatile Volts, ohms, lOA, diode test Autorange 0.7% basic de accuracy 2000 + hour battery life 3 year warranty ACCESSORIES Here are some of the wide range of accessories available, * 80i- 410 * 80T-150u 5 to 400A hall effect ac/dc clamp- on current probe. WAS $310.00 NOW $234.00 Universal temperature probe WAS $279.00 NOW $218.00 *SOTK Type K thermocouple module for use with interchangeable probes * ClOO WAS $142.00 NOW $107.00 DMMS WAS $84.00 Universal carry case for all handheld NOW $56.00 (All prices are recommended retail prices exclusive of Sales Tax) Available from the following stocking distributors: ACT: John Pope Electrical, (062) 80-6576. Aeromotive MaintenancE> Services, (062) 85-2377. NSW: Ames Agency, 699-4524. J. Blackwood & Son, 609-0111. George Brown & Co, 519-5855. OGE Systems, (049) 69-1625. Ebson, 707-2111. Macelec, (042) 29-1455. Obiat, 698-4776. Petro-Ject, 569-9655. David Reid, 267-1385. NT: J. Blackwood & Son, (089) 84-4255. Haymans, (089) 84-3422. QLD: Auslec, (07i 854-1661. Petro-Ject, (07) 252-2777 St Lucia Electronics, 52-7466. L. E. Boughen, 369-1277. Haytech, 844-9396. Thompson Instruments (Cairns), (070) 51-2200 Nortek (Townsville), (077) 79-8600. SA: Electech (08) 277-1533. Petro-Ject, 363-1353 . TAS: George Ha rvey Electric, (003) 31-6533. Petro-Ject, 44-8400. VIC: Radio Parts Group, 329-7888. George Brown & Co, 878-8111. Electech, 482-1577. Petro-Ject, 877-4122. J. Blackwood & Son, 542-4321. Factory Controls, (052) 78-8222. Mektronics, 587-3888. WA: Atkins Carlyle, 481-1233 . Dobbie Instruments, 478-1366 Electronics for Everyone Pt.2: What you need to know about capacitors • • • Most electronic circuits use one or. more capacitors. Next to resistors, they are the most common passive electronic component. And like resistors, they present big problems for beginners because of the different ways of labelling. By LEO SIMPSON A capacitor is a component which stores electric charge. Capacitors stop the passage of direct current (DC) but allow alternating current (AC) to pass though. The higher the frequency of the AC, the more easily it will pass through a capacitor of given value. And for a given AC frequency, the smaller the capacitor value, the less current will flow. There is a vast amount of electronic theory associated with the design and use of capacitors in circuits but we will not deal with any of that material here. This article is mainly devoted to recognising capacitor values on circuits and then recognising equivalent values on actual capacitors. That may seem simple but it isn't. The first working capacitors were glass jars with metal foil electrodes inside and outside. These were known as Leyden jars (because they were invented in Leyden, Holland). These days there is a great variety of capacitors but they all have two features in common: two electrodes or plates which are separated by an insulating medium known as the dielectric. While capacitors are not as common or as visible as resistors in everyday life, they are widely used in electrical and electronic appliances and in cars. Common examples of capacitors are the can units often mounted on electric motors. These are " motor start" or "motor run" capacitors. They are also used to suppress commutator sparking in brush-type electric motors, as the points condenser in automotive ignition systems and so on. The unit of capacitance The unit of capacitance is the Farad named after the eminent British physicist, Michael Faraday (1791 - 1867). The Farad is defined as the capacitance which will store one Coulomb of charge (equivalent to 6.24 x 10 1 9 electrons) at a potential of one volt. In practice, the Farad is an extremely large unit of capacitance although values of one Fa rad or more are available. Most capacitor values that you come a cross will be expressed in microfarads, nano- \ These capacitors all have a nominal value of O. lµF although they have different labels. Three have the obsolete "MF" or "MFD" label while several use the IEC code 104. One is labelled "ul" while another is "100n". 0.47uf INPUT-1111-----+--I Fig.1: this circuit has two capacitors, one at the input and one at the output. farads or picofarads. In old textbooks on electricity you might come across the terms condenser or capacitator. The term condenser is an obsolete term for capacitor while capacitator was, and sometimes still is, just a mispelling. Recognising capacitors on circuits Fortunately, capacitors are always easy to recognise on circuits as they are drawn virtually the same way around the world. They are depicted as two electrodes with no connection between them. Fig.1 shows a circuit with two capacitors, one at the input and one at the output. With capacitors used like this, you would say the circuit was AC-coupled (meaning it will not pass DC signals) or capacitor-· coupled. Sometimes capacitors are shown on circuits with a " + " sign next to one electrode or with one electrode drawn as an outline and the other solid. These are symbols for polarised electrolytic capacitors, a broad class of capacitors which we will deal with in the next episode in this series. Fig.2 shows a circuit with two electrolytic capacitors in it. The '' + '' sign next to one electrode indicates the polarity of the capacitor. The capacitor must always GNO 470uF 16VW + _ 10uf 16VW + _ Fig.2: the two electrolytic capacitors in this circuit have their polarity shown with plus and minus signs. Fig.3: another way of showing electrolytic capacitors with the negative electrode in solid black. /\ l'lllL '1989 5 . These are epoxy dipped flat metallised polyester capacitors, commonly known as greencaps. Note that conventional and IEC labelling is used to show the capacitance and tolerance. These very small O.lµF capacitors, contrasted with the greencaps, are monolithics. These are multilayered ceramic capacitors mainly used for bypassing. be connected into circuit so that the positive electrode is always more positive (in voltage) than the negative electrode. Fig.3 shows the same circuit as Fig.2 but with the outline symbol depicting the positive electrode of the capacitors. Types of capacitor There are many different types of capacitor and they are usually ref erred to by the name of their dielectric. For example, a ceramic capacitor has a ceramic dielectric while a polyester capacitor has a dielectric of polyethylene terephthalate, or polyester for short. A mica capacitor has sheets of mica as the dielectric. 6 SILICON CHIP In this episode. we shall concentrate on film and ceramic capacitors. Let's list some common film capacitors: polyester (also known as polyethylene terephthalate or PETP), polycarbonate, polypropylene, polystyrene, paper and mixed dielectric (eg, paper and polyester). Polyester capacitors are also sometimes referred to as Mylar capacitors. Then we have to split film capacitors into two more classes: metallised film and film/foil. The metallised film type is probably the most widely used capacitor today but the film/foil type is still used in very large numbers. The film/foil capacitor is also the easiest to understand. It is made by winding two long pieces of thin metal foil (usually tin or aluminium) and two plastic films (these days usually of polystyrene). The two films are wider than the metal foils (plates) and so fully isolate them from each other and from any external contact. If you have a look at a polystyrene capacitor you can easily see their wound construction. Naturally, there is a lot more to making any capacitor than just winding plastic films and metal foil together but we don't plan to go into the details here. Suffice to say that chemistry and metallurgy have a very large part to play in the manufacture of today's extremely reliable capacitors. In a metallised film capacitor, the two metal foil electrodes are missing. Instead, there are just two plastic films and these have a very thin layer uf metal vapour deposited on one side. This metallisation takes the place of the foils in film/foil capacitors. Because separate foils are not used, metallised film capacitors are always smaller than film/foil capacitors of the same capacitance and voltage rating. These days metallised film capacitors are the general purpose types while film/foil capacitors are used in more specialised applications. Ceramic capacitors Almost all ceramic capacitors are made from a disc or square of barium titanate with an electrode of silver screen-printed on each side. A wire lead is soldered to each electrode and the whole assembly is dipped in an epoxy mixture to seal it from the effects of the atmosphere. Ceramic capacitors are mainly used in radio frequency (RF) circuits, such as is found in radios, TVs, VCRs, CB radios and so on. By the way, we are talking about fixed capacitors here, meaning that the value of capacitance is not adjustable or variable through a given range. Values of capacitors As mentioned above, the Farad may be the standard unit of capacitance but it is a seldom used value. The capacitors you come across will have values in microfarads, nanofarads or picofarads. Now let us explain those prefixes. You've probably already come across the the prefix micro; it means millionth or 10- 6. So one microfarad is one millionth of a Farad. Nano is the prefix for 10- 9. One nanofarad is one thousandth of a microfarad. Pico is the prefix for 10- 12. One picofarad is one millionth of a microfarad. Having proceeded this far, we can also state that one nanofarad is equal to one thousand picofarads. Also, one microfarad is equal to one thousand nanofarads or one million picofarads. Abbreviations Rather than spell out the words micofarad, nanofarad or picofarads, we use abbreviations, just as we do with resistor values. Hence, · picofarad is pF, nanofarad is nF and microfarad is µF where the Greek symbol "µ" stands for millionth. Sometimes you may come across capacitors which are labelled in MF or MFD. These are now obsolete (and incorrect) abbreviations of microfarad but which still turn up on new capacitors. Until fairly recently, it was usual to express all capacitor values in terms of picofarads or microfarads; normally, all values above lO00pF were expressed in terms of microfarads. Nanofarads were not used. Now they are, in circuit dia grams, technical literature and on the capacitors themselves. However, the adoption of nanofarads has been far from universal and there tends to be a lot of confusion among enthusiasts when interpreting capacitor values. The situation has been made a lot more confusing because of the use of the IEC (International Electrotechnical Commission) labelling on circuits and EIA coding on capacitors. In the IEC labelling system, the multiplier letter is used instead of the decimal point [just as R. k or M can be used instead of the ,;"4*~~ ~-\ \4'ft.s~. Conventional film/foil capacitors have two plastic films and two metal foils wound tightly together and sealed. This photo shows polystyrene capacitors being wound at the Allied Capacitors plant, at Brookvale in Sydney. This is a selection of polystyrene capacitors. These quality capacitors are notable for their extremely high insulation resistance, typically more than 1 million megohms, or one Teraohm! decimal point in resistor values see the first episode in this series). So instead of labelling a capacitor value as 3.3pF on a circuit. the IEC label would be 3p3. For a 1.5µ,F capacitor, the IEC la bel is 1µ5. The issue becomes more complicated when nanofarads come into the picture. For example. a capacitor with a value of .0012µ,F may be specified as 1200pF or 1.2nF. Its IEC la bel is l n2. Similarly. a .OlµF capacitor can be specifed as lOnF and its IEC label is 10n. A 0. lµF capacitor can be specified as lO0nF and its IEC label is 100n. You ma y even see it labelled as ril. On SILICON CHIP circuits and on those in many othl'lr magazines. it is normal practi ce to omit the "riF"' from the va lue. la rgely for clarity and to sa ve space. For small capacitors expressed in picofarads. , \1'1111. rn1rn 7 manly used capacitors these days are metallised polyesters . Typically, these are finished with a green epoxy resin and so they are commonly ref erred to as greencaps. Another capacitor you might hear about is the monolithic. These are very tiny multilayer ceramic capacitors which are coming into fairly widespread use. They are commonly blue in colour and so are often ref erred to as skycaps although colours other than blue are also used. EIA codes These are metallised paper capacitors specially chosen for their "self healing" properties on 250VAC. These are labelled 4n7 and 4700pF. "pF" is always included in the value. Capacitor jargon In normal conversation, or when buying capacitors at your local electronic parts shop, it is common to refer to a O. lµF capacitor as a "point one mike capacitor". Similarly, a lOµF capacitor would be referred to as a "ten mike capacitor" or "ten mike cap". It is also usual to refer to electrolytic capacitors as "electros", so a lOµF electrolytic capacitor would be referred to as a "ten mike electro". For lower value caps, it is usual to refer to the value directly. For example, a lOpF capacitor would be called a "ten picofarad capacitor". As noted above, the most corn- Now if you have absorbed all that, you are doing very well. But there is at least one more hurdle for the novice [and the well experienced) to overcome before they can be sure of interpreting capacitor values correctly. This hurdle is the EIA code. EIA stands for Electrical Industries Association and is a US organisation. The EIA code uses 3 digits to specify the capacitor value, together with letters to specify tolerance and voltage rating. Fig.4 shows the general scheme, with two capacitors depicted. 220pF 'j:1Q¾ .047uf ±5%1 HH11:::;JI~i l.!...__ MULTIPLIER L__ TOLERANCEEIA CODES Fig.4: most capacitors using the EIA code will be labelled like these. The letter at the end indicates the tolerance. If they don't have a letter they can be assumed to be ± 20%. t I f f \ \ , I l \ II These low voltage ~eramic capacitors are used in RF circuits. Those labelled NPO or with a black cap have zero or very low temperature coefficient. 8 SILICON CHIP The first two digits give the two most significant figures in the capacitor value while the last digit is the multiplier [to the base 10), with the whole value expressed in picofarads. To give a few examples: (1) 150pF = 15 x 101 (2) .0033µF = 3300pF = 332 = 151 = 33 x (3) .068µF = 68,000pF = 68 x 103 = 683 102 ~ ******** ~ DON'T BE A FOOL THIS APRIL M~\TI.~~~;~i;~~ \'r'"' DUAL TRACE OSCILLOSCOPE * • • • • 1 YEAR WARRANTY , - - . _ . . 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POWER SUPPL y 3 v, 4 5 v, 6 v, 7 _5 v, gv, 1 2v <at> 5 oomA ONLY $36.95 SCOPE ACCESSORIES We stock a wide range of SCOPE accessories for MINISCOPE, SUPERSCOPE, SCOPE CORDLESS, Table 1: Capacitor Markings in the E12 Series Value Alt value IEC value EIA code Value Alt value IEC value 10pF 12pF 15pF 18pF 22pF 27pF 33pF 39pF 47pF 56pF 68pF 82pF 10p 12p 15p 18p 22p 27p 33p 39p 47p 56p 68p 82p 10K 12K 15K 18K 22K 27K 33K 39K 47K 56K 68K 82K .01µF .012µF .015µF .018µF .022µF .0271,tF .033µF .0391,tF .0471,tF .0561,tF .0681,tF .0821,tF 10nF 12nF 15nF 18nF 22nF 27nF 33nF 39nF 47nF 56nF 68nF 82nF 10n 12n 15n 18n 22n 27n 33n 39n 47n 56n 68n 82n 100pF 120pF 150pF 180pF 220pF 270pF 330pF 390pF 470pF 560pF 680pF 820pF 100p 120p 150p 180p 220p 270p 330p 390p 470p 560p 680p 820p 101K 121K 151K 181K 221K 271K 331K 391K 471K 561K 681K 821K 0 .1µF 0 .12µF 0.151,tF 0 .181,tF 0 .221,tF 0 .271,tF 0 .331,tF 0.391,tF 0.471,tF 0 .561,tF 0 .681,tF 0.82µF 100nF 120nF 150nF 180nF 220nF 270nF 330nF 390nF 470nF 560nF 680nF 820nF 100n 120n 150n 180n 220n 270n 330n 390n 470n 560n 680n 820n 1n 1n2 1n5 1n8 2n2 2n7 3n3 3n9 4n7 5n6 6n8 8n2 102K 122K 152K 182K 222K 272K 332K 392K 472K 562K 682K 822K 1.0µF 1 .2µ,F 1.5µF 1 .8µF 2 .2µF 2 .7µF 3 .3µF 3 .9µ,F 4.7µF 5 .6µ,F 6.81,tF 8.21,tF 1 O.OµF .0011,tF .00121,tF .0015µ,F .0018µ,F .00221,tF .0027µ,F .0033µF .0039µF .0047µ,F .0056µF .0068µF .0082µF 1nF 1.2nF 1.5nF 1.8nF 2 .2nF 2 .7nF 3.3nF 3 .9nF 4.7nF 5.6nF 6.8nF 8.2nF (4) 0.47µF = 470,000pF = 47 x 104 = 474 Values from lOpF to 82pF are a special case in that they have no multiplier so they just have a two digit code. For example, a 56pF capacitor just has the code 56. After a while you stop thinking about adding a number of zeros to get a value in pF. Instead, you will eventually recognise any three digit code ending in '1' as applying to capacitors from lOOpF (101) to 820pF (821); any code ending in '2' as applying to capacitors from .OOlµF or lnF (102} to .0082µF or 8:2nF (822}; any code ending in '3' as applying to capacitors from .011,tF (103) to .082µ,F (823); any 10 SILICON CHIP EIA code (10% tolerance) (10% tolerance) 1u0 1u2 1u5 1u8 2u2 2u7 3u3 3u9 4u7 5u6 6u8 8u2 1 Ou 103K 123K 153K 183K 223K 273K 333K 393K 473K 563K 683K 823K 104K 124K 154K 184K 224K 274K 334K 394K 474K 564K 684K 824K 105K 125K 155K 185K 225K 275K 335K 395K 475K 565K 685K 825K 106K Large capacitors with a value of more than 1µ.F, such as these 4.7µ.F units on the left or the 250V AC units on the right, are usually metallised polypropylene . code ending in '4' as applying to capacitors from 0.1µ,F (104) to 0.82µ,F (824) and so on. Tolerance Combined with the 3-digit code is usually a letter to indicate the tolerance. Most capacitors sold over the counter these days have a tolerance of ± 10 % and the letter to indicate this is K. The letter tolerance code is similar to that for resistors but there are significant differences. For capacitors of more than l0pF, the tolerances are as follows: z ................... - 20 % , + 80% Y .............. ..... - 20 %, + 50% w ................. -20 %, +40% P.. ................. - 0 %, + 100% N .................. ± 30% M .................. ± 20% L ............. .. .... ± 15 % K .......... ......... ± 10 % J.................... ± 5% G................... ± 2% F ................... ± 1% What about the colour code for film capacitors? In this article on capacitors there is no mention of the colour code, as applied to dipped plastic capacitors made by Philips. This has been deliberate because the capacitor colour code appears to have fallen into disuse as far as film capacitors are concerned. 1 5 or 20 years ago when colour code capacitors were commonplace, they were nicknamed "licorice allsorts" because of their striped appearance. Since it is possible that you will still come across colour coded capacitors from time to time , you will want to know what the code is. Basically, it is very similar to the resistor colour code. The bands run from the top of the capacitor down towards the leads and the first two colours are the first two digits in the capacitor value. The third band is the multiplier, giving the value in picofarads. For example, a capacitor with the first three bands reading yellow, violet, red has a value of 4700pF, or .0047µ,F. The fourth band is the tolerance band with black being 20% and white 10%. Finally, the fifth colour band is the voltage rating, as follows: brown , 1 00VDC; red, 250VDC; yellow, 400VDC and blue, 630VDC. For capacitors of less than lOpF, the tolerances are as above except for those listed below: G.......... ......... ± 2pF F.. ................. ± lpF D................... ± 0.5pF C.... ... ............ ± 0.25pF In practice though, you will find that the vast ma jority of film capacitors sold over the counter in Australia are of 10 % tolerance and so will have the letter K following the 3-digit code. To help you recognise the EIA code, we have listed all values in the E12 series (see last episode for an explana tion of E-series) from l0pF to 10µ,F in Table 1. In the first column of Table 1 you'll see capacitor values as normally shown in SILICON CHIP and a number of other magazines. In the second column is an alternative equivalent value, where appropriate, in nanofarads. In the third column is the IEC label, as mostly found on circuits of European · origin. Finally, the fourth column shows the EIA code with the letter K added to show that the capacitor has 10 % tolerance. In the full EIA code system there are many other letters to designate capacitor type, application, voltage Each one of these capacitors has a value of 1µF and they are all labelled differently. All are currently .available except the Ducon polyester unit. rating, temperature coefficient and so on but they seldom. appear on general purpose capacitors sold over the counter. We won't go into more detail to avoid adding confusion. Nor have we covered every possible permutation that is possible in labelling and depicting capacitors; they are too numerous to list them all. However, having carefully read this article, you should be able to recognise and interpret any capacitor value you come across from now on. These days many digital multimeters will measure capacitance. So, if you can't be sure of a capacitor's value, check it with your meter. This is a good idea too because it can save installing a faulty unit into circuit. ~ APRIL 1989 11 19" Zip Racks Reductions! The racking system that solves all your equipment mounting needs. Made from heavy duty aluminium, it comes with all necessary hardware and can be assembled in minutes. Measures 540 (W) x 360 (D) x 675mm (H). Cat H-2469 SAVE $20! Now s79 50°/o OFF! Imperial Linear Rotary Pots 19" Rack Mounting Case Cat No Now Only 1ype 1/4" 500 Ohm Single R-1801 1/4" 5K Ohm R-1805 1/4" 10K Ohm R-1806 1/4" 20K Ohm R-1807 75c 75c 75c 75c 1/4" 50K Ohm R-1809 1/4" 500K Ohm 70c 70c $1.50 R-1840 $1.50 R-1812 1/4" 100K Ohm Dual CAN'T USE IT, IF YOU LOSE IT! Keep all your bits and pieces where you can find them. Handy modular draw systems are the economical answer. Clip them together for your own custom built storage system. Two Drawer System Primary: 240V. 50Hz Secondary Voltage: 6.3 - O• 6.3V Secondary Current: 150mA Terminators: Flying leads Cat M-2851 s5as Great for anything from the USA. 240 volt input, 60VA capacity. In sturdy metal case with 2 metre cord and inbuilt fuse. Cat M1156 DSE0144 Primary: 240V AC Secondary: 28 - 0 - 28V Secondary current: 2A Cat M-0144 s34as Low Profile - Ferguson All 240V primary with two seperate secondary windings. Fitted with round pin terminators. All measure DSE0150 300 Watts! Primary: 240V Secondary: 47 - 0 - 47V 110x50x65mm. <at> 3 Amps 15- O- 15V<at> .5 Amps Current: 300VA Terminations: Flying Leads Size: 115 x 95 x 97MM Cat M-0150 PL12/20VA. 2 x 6V<at> 1.7A 2 X 6V<at> 3.4A 2 X 12V<at>1.7A Cat M-3596 Primary: 240V AC Secondary: 18 volts <at> 6A Terminations: Flying leads Cat M-2000 PL15/20VA. 2 x 7.5V<at> 1.3A 2 X 7.5V<at> 2,6A 2 X 15V<at> 1.3A Cat M-3597 DSE2010 PL18/20VA. 2 x 9V<at> 1.1A 2 X 9V<at> 2.2A 2X18V<at>1.1A Cat M-3598 DSE2000 s35as 18 volts at 14 amps continuous. Ideal for linear amplifiers, etc. Suits 13.8V 25A (peak) supplies. Cat M-2010 segas DSE2155 Primary: 240V. 50Hz Secondary Voltage: 6.3,7.5, 8.5, 9.5, 12 & 15V Secondary Current: 1 amp Terminations: Flying Leads Cat M-2155 PL24/20VA. 2 x 12V <at> .85A 2 X 12V<at> 1.7A 2 X 24V<at> .85A Cat M-3599 PL30/20VA. 2 x 15V<at> .69A 2x15V<at>1.3A 2 X 30V<at> .69A Cat M-3600 PL40/20VA 2 X 20V <at> .51A 2 X 20V<at> 1A 2 x 40V<at> .51A Cat M-3601 DSE2840 Primary: 240V, 50Hz Secondary Voltage: 4.5- O4.5V Secondary Current: 150mA Terminations: Flying Leads Cat M-2840 s5as Tilt Drawer System Cat H-2580 115 Von Stepdown DSE2851 11$69 Justs5495 1/4" 20K Ohm Dual R-1836 Quality transformers Bargain Prices! 95 High quality, black instrument case which fits standard 19" racks. Just the thing for mounting amps. etc. And it looks great too! Cat H-2481 All Just s2995 ea s495 Cat H-2581 300/o OFF POPULAR CHIPS Type Description 74LS10 74LS13 74LS14 74LS21 74LS27 74LS30 74LS54 74LS83 74LS95 74LS109 74LS196 74LS138 74LS153 74LS165 Triple 3 input NAND gate DL 4 in NAND Schmitt trigger Hex Schmitt trigQer Dual 4 input positive NAND gate Triple 3 input NOR gate 8 input NAND gate 2 way and/or inv 4 bit full bi nay array 4 bit L-R shift register Dual JK flip flop Decade counter 3-8 decoder/demulti Dual 4 input multiplexer Par load shift register Cat No Z-4910 Z-4913 Z-4914 Z-4924 2-4927 2-4930 2-4954 2-4983 2-4995 2-5109 Z-5196 2-5184 2-5186 2-5188 Now Only 52C 52c 59C 87c 59C 88C 88C $1.36 94C 80C $1.71 84C 84C $1.71 300/o OFF COMMON CMOS CHIPS 74C14 4007 4009 4011 4015 4023 4030 4046 4093 4511 4516 4518 4526 Hex Schmitt trigger Dual comp pair with inverter Hex inverter buffer/level shift Quad 2 input NAND Dual 4 bit shift re~ister Triple 3 inrut NA D gate Quad EXC USIVE OR gate Phase-locked-loop Quad 2 inpu1 NAND Schmitt trigger BCD/7segment decoder/driver/latch Presetta le up/down counter Dual BCD up counter 4 bit programmable down counter 2-5413 2-5607 2-5609 Z-5611 2-5615 2-5623 2-5630 2-5646 2-5693 2-5730 2-5738 2-5740 2-5744 $1.05 56C 94C 49C $1.00 88C 88C $1.36 98C $1.71 $2.06 $1.50 $1.50 300/o OFF HIGH SPEED CMOS CHIPS 74HC08 74HC11N 74HC27 74HC30 74HC32 74HC76 74HC85 74HC139 74HC157 74HC165 74HC174 '74HC367 Quad 2 input AND gate Triple 3 input Dual JK flip flop 8 input NAND ~ate Quad 2 input O ~ate Dual JK master/save flip flop 4 bit magnatude comparator 1 of 8 decoder/multiplexer Quad 2 inJ>Ut multiplexer Par load bit shift register Hex D-type flip flog Hex bus driver & state o/p 2-5808 2-5811 2-5827 2-5830 Z-5832 Z-5876 2-5885 2-5920 Z-5925 2-5930 2-5935 2-5960 ,;J,>Jln,~~$§ PHONE AND MAILORDER SEVICE s475 88C 88C 88C 88C 88C 87C $1.36 87c $1.36 $1.57 $1.36 $1.22 ORDER BY PHONE 008 22 6610 (NO STD charge outside Sydney area) SYDNEY AND ENQUIRIES 888 2105 FAX (02) 805 1986 OR WRITE TO DSXPRESS P.O.BOX 321 Nth RYDE NSW 2113 ALL MAJOR CREDIT CARDS ACCEPTED. OVERNIGHT COURIER AVAILABLE 24 HOUR DESPATCH OF ALL ORDERS. THE HEAT IS 200/o OFF! HELPING HANDS GREAT SAVINGS Aluminium Heatsinks Universal Hole Pattern. Predrilled for instant mounting. Cat H-3410 Now 760 . . Round T0-5. Snug fit on T0-5 cases Cat H-3412 Heavy Duty Powerfin. For the big jobs. Onlv , Cat H-3426 ' 1279 Economy Power Heatsink. 75mm undrilled. Cat H-3470 *3 19 Predrilled Economy. Accepts two power transistors. Cat H-3471 Square Finned High Power. Square section measuring 138(W) x 262mm(L) Cat H-3472 Just *1 gee Barrier Strips PCB Mount Terminal Connectors Screw type. 4-Way with pre-tinned solder lugs and mounting holes. Cat H-6704 75 Was $3.75 Now s2 6-Way. Ideal for connecting external lead to PCB. Cat H-6748 75 Stubby Screwdrivers Was $2. 75 Now s1 ~ Extra Memory? Dynamic Rams Stereo Speaker Connector If you're a little short on memory, you'll find we stock most D Rams at the most reasonable prices around. .. 4 terminals. Positive locking connection. ;.;;;'~ 4116 s2as Universal Knobs 28mm Black Aluminium. ~~ Only I 7Qc •19!I •29es 25C At this price, you may as well make a job ofitandgettheentireset.CatT-3570 NOW ~~ s5~5 ~ Save $41 ~ Bargain/ Metal Bender Make your own instrument cases, etc with this amazing value metal bender. You'll pay up to $119 elsewhere. Handles the most used gauges. Cat T-5250 • $2 OFF/ Adjustable Cutter/ Stripper Extra heavy duty plier type wire stripper. Easy to use. Was $69.95 Was $5.95 Only 53911 NOW $ ~~ 41256 slides. Cat H-9008 Flat Blade Cat T-6060 Philips Cat T-6065 ~-•:==~ . . ~~== ~~~~-~~am•3" .. ~- s7as 256K.120ns.Oneofthemostcommon Equalizer. B!!!c_k to suit equalizer RAMs. Suits IBM PC. Cat Z-9313 Stainless Steel Needle Nose Big enough for plen: of leverage~ small enough to fit most jobs. Flat blade 105 X 6.5mm Cat T-6050 lncr,dib/B 64K. 20ns. Suits Apple II and Commodore. Cat Z-93 12 ,r *1"u ~ =-~•::r:'l~~ ,..- 4164 <at> • Heavy Duty 16K memory suits older style processors. Cat Z-9310 Less Than 1 /2 Price! They'll get you out of a tight spot. Flat Blade. Cat T-6020 Philips. Cat T-6025 4995 EXTRA VALUE LED'S 5MM Flashing Rectangular Easy to use, great for virtually any application. Premium quality rectangular LED. Matched 5 volt, 3Hz. Cat Z-4000 brightness, consistent quality. 2mm x 5mm. ~ Ideal for bar graphs. Cat Z-4093 •1711 2O0/o OFF TRANSISTORS Type Cat No Now Only BUX80 BF469 BF470 DS549 MPF106 MJE2955 TIP31B TIP32B BF463 2N6557 2SC710 2N2222A 2N3948 2N4427 Z-2150 2-1635 Z-1636 Z-1319 Z-1840 2-2005 2-2020 2-2024 2-2040 Z-2041 2-2512 2-2069 2-2260 Z-2506 $8.38 $1.40 $1.40 12C $1.12 $1.80 I ~ 7 Segment Display 13mm 7 Segment 8mm. 7 S~r!Jent display. High brightness common cathode. Cat Z-4103 711 Another high brightness common cathode display at a value plus price. Cat Z-4151 '2 '2" Soldering Iron $1.58 $1.58 45C 45C $1.58 78c s9s5 $4.78 $3.40 AUTHORISED STOCKISTS: N.8.W.: BALLINA: laltln1 11-onlco 88 7022 BOWRAL: F.R.H. Eloc:trtcll 81 1881 BROKEN HILL: H - I Eltctronlco 88 4098 CHARLESTOWN: New1ronlco 43 9600 COFFS HARBOUR: Colla Harbour Eltctronic■ 52 5684 DUHO: Chrio'■ HI FI 82 8711 FORSTER: Fomor VIiiage Eltctronlco 54 5008 GLEN INNES: John Sommertld Eleclronlco 32 3661 GRAFTON: Ropalra and Sparw 42 1911 GRIFFITH: Ml11ronlco 82 4534 INVER!LL: Lrn WIH1119 Electronlco 221821 LIIMORE: Docro !lectronlc S""'lcn 21 4137 MOREE: MOfff Electronlco 52 3458 MUDGEE: H•-•re 72 3895 NOWRA: Nowr1 Eleclronlco ·21 0722 WAGGA WAGGA: PhUllp■ Eltctronlco 21 6558 VIC:MORWELL: Morwetl Electronlco 34 8133 8HEPPARTON: Phllllp■ Eltctronlc■ PI)' Ltd 21 9497 WARRNAMBOOL: Marrtronlco 62 9870 OLD: IUNDAIIERG: Bob Elttln Eltctronlco 72 1785 KINGAROY: HolfflOI Todor Electronlco 82 1658 MACKAY: Steven■ Electronic■ 51 1723 MARYBOROUGH: Koller Electronlco 21 4559 TAB: DEVONPORT: A.I . Electronic■ 24 8322 SA: LOXTON: G I 8 EIIC1rtc1I 84 7495 MT GAMIIIER: H - • • CommunlCltlon Centre 250400 WA:ALBANY: Micro Eltctronlco 41 2077 BUNIIURY: Micro Electronlco 21 6222 GERALDTON: l1IIYl1 Llalltlna I Electrical 21 1988 KARRATHA: DIYH OICllronlc 85 4836 &oc DIC The go anywhere soldering iron that just clips onto the car batte~ or any 12V source. Fast heating, its lightweight and comes with 2 metre leads and large alligator clips. Cat T-1915 Brand NEW kit's are now in stock! Here are just a few. Don't miss our complete range of exciting do-it-yourself projects in our bigger, brighter 1989 catalogue - Out Soon! BeepoCont1nuity Tester Audio Oscillator At last, an audio oscillator that is both simple and inexpensive! This unusual approach has led to a design which uses high performance op amps together with a clever third harmonic cancelling network. This has lead to a circuit that is far simpler and cheaper than current high-tech (and high priced!) designs. Plus it can easily be converted to a Low Distortion Oscillator by inserting an RA53 Thermister (Cat R-1796). sgg Cat K-7300 PCB Short Locator A great idea that can save you hours of unnecessary work. This easy to build project can help locate shorted tracks on PCB's. Because it uses Audio Tone, you'll know instantly where the fault is, without taking your eyes off your work to check meters, etc. Practical, simple and inexpensive. Cat K-7400 JustS29 95 ~~~~~t:·.:~:::--·-,,,,...- Dent Preventer! ~ _,; Reversing Car Alarm More Great Kits! Microwave Leakage Detector. Cat K-3095 .... $12.95 Handsfree Phone Adaptor. Cat K-3100 ....... ..$89.95 High Energy Ignition System Cat K-3302 ...... $45.95 Capacitance Meter Cat K-3410 ...... .... ...... .. .. $19.95 General Purpose Preamp Cat K-3427 ......... ... $13.95 Voi.ce Synth~sizer Cat K-3510 .. ........... ... ..... $29.95 Guitar Practice Amp Cat K-3548 .. ................$39.95 30W Stereo Amplifier Cat K-5100 .... .. ........ .. $99.95 13.SV SA power Supply Cat K-7110 .. ..............$119 Prox-Motion Detector Cat K-8100 ................ $36.95 UHF Remote Transmitter Key Cat K-8150 .. ... .$16.95 Component Grab Bag 1(Asst) Cat K-9010 Approx. value $14 .... ... .... .... ........ .......... ... .... ... ......... .$4.95 Component Grab Bag 2(Asst) Cat K-9020 Approx. value $24 ........................... .................... .... .-$9.95 Component Grab Bag 3(Asst) C'at K-9030 Approx. value $50 ......................... .... .. ... ..... ... .. ...... $19.95 Introducing, Beepo winner of the Grand Hobby Electronics Contest! Pocket sized it features three tones over six decades of resistance, automatic polarity reversal to save lead swapping and an ambient current so low that it needs no on/off switch. It's a must for trouble shooting and provides a much faster response than a digital multimeter. Cat K-7700 With the high cost of panel repairs (even a small bump can cost hundreds of dollars) this project is a real saver! The Reversing Car Alarm is a simple ultrasonic indicator, which when mounted on the rear of your car, gives you an audible signal if you get too cl~se to any large Object. Cat K-4600 s39es Transistor Beta Tester Simple to build, easy to use! This fantastic Transistor Beta Tester allows you to measure the gain of any bipolar transistor in seconds. Just connect a transistor, push 'the button, rotate the knob and read off the beta scale there's no meter required! ,,;::;-;:,,~~ CatK-7200 JustS19 95 Things a little fuzzy? You'll get a great reception, an incredible range and the best prices on TV antennas and all accessories when you shop at Dick Smith Electronics. NEW TV ANTENNAS FOR '89! UHF Deluxe Multiband ~ Multiband UHF For Medium Signal Areas! The latest design in 23 element multiband UHF antennas for medium signal. Covers Band 4 &_5 Channel 21 to 69. Excellent antighosting antenna for those difficult areas. Includes antenna balun for coaxial cable connection . Cat L-4086 s79es For Deep Fringe Areas! UHF band 4 & 5 channel 21 to 69. With an incredible 91 elements for deep fringe signal reception at its best. Quality construction means it'll withstand the elements without corroding all over the place. Comes with antenna balun for coax connection. Cat L-4088 5 149 - ~ - - - - For Long Distance! Phased Array A fantastic VHF antenna for country viewers! You'll pick up signals over 100K from the transmission centre. Gives you the opportunity to get all the big city stations. You can easily install it yourself and save costs. Cat L-4025 Combined UHF/VHF/FM Top performance and the highest quality. Ideal for medium reception areas. Saves the hassle of two antennas. The very latest in design, this superb high gain antenna gives the best reception and minimum ghosting. Easy to install yourself on your existing antenna mast. Cat L-4021 YES, WE CARRY CABLE, CONNECTORS ... THE LOT/ 5 129 Great Savings All This Month On Computer Peripherals! . Suits IBM, Apple & Commodorel w,,, $29.95 ea Now =n:~,;,'•' ..,on...,a,,oo,:~,:::.::::,;:~;,;~'~;;::::.",,on, 5i:~ii~?u;;;;,~;;:~~;;\;;;;~~;;,~~;;~;::::·Spa~ Buos !~~l~,~~~!~~~rify of ai=~~1 ~I~ ~~~~c2~~mia~0~~~~~~t,~u;eri~cr~~e our amazing special offer! Paper white TTL monitor and Hercules compatible MGA card at this once only low price. Monitor Cat X-2400 MGACard Cat X-8141 i:: I .. □ 1··!'., · Both For Only $!:'!I SPECIAL PURCHASE! Top Nams lntsrnaJ Modsm. The ' manufacturer blew-it, so you've got the chance to get the amazing Bit Blitzer Internal Modem at a fraction of its normal cost. Comes with full $ guarantee and all the Bit Blitzer features. Cat X-3304 L 199 1'•"'.'..,s•>I' I ~~~L,lNE.lSWf1!l 1 , ... ============= i.%!' 11 1 ~~ •... L .... _ , I , . r• ... . ... 1 \\ l\l\\!\:!\\l:! :1:i:::::;:::.,:········..:•···· Fast Action Joystick ::.,:.,,.==.=,.::.:.,. I ~ ..=..=':.':.':.':.=....=:.=..:.:.,.·=.=,:.=,·=.,·'·' .: ....:'....;..,, ··.··.·. M :~.::...:·.::~.:.·.:.=.·,.·.:.:.:.:.:.:.:.,.:.,.:.~ .::'·:.~.•.:.•.;.·.::.;.:.•.'.:.~.:.'.:.:.:.:·:·:·:·:.:.;·:·:.:.:.:.:.\.!·!·i·i·i·i·i.i_i·!·!.:.i.l . DISK-KIT! Software And storage In One Hit. A low cost joystick that gives high quality performance. Uses microswitches instead of contacts, so it's ultra reliable! Cat X-3830 Just : :,:::,,:. ·•,••·:·:-: s2995 It's by far the best way to buy your floppy disks. Disk-Kit comes with 50 hi~h quality Xidex DS/DD 5 1/4" diskettes, impact resistant plastic storage box with lockable lid .. ..Plus Data Manager PC software. Cat X-3522 llnbslisvabls Va/us/ Only s149 ENORMOUS SAVINGS - LIMITED STOCK ITEMS! • BablAT Motherboard 6/8/10/12MHz Cat x-1000 Save $150 $399 • XT/ :r 360/1.2M Roppy Disk Controller Cat X-2014 Now Only $89 • DSE V21/V23 Modem Cat X-3300 $50 OFF $1 49 • RS232 Breakout Box Cat X-3568 Near 1/2 ~rice! $14.95 ·• Backgammon IBM Software Cat X-9016 $20 OFF $49.95 • Mouse Systems PC Paint Plus Cat X-9500 Only $49.95 • GW BASIC for Multltech Computer. Genuine Microsoft Version. Limited Stocks Only. Cat X-5249 Outstanding Valuel $19.95 Cable Savers! All J t • Serial Cable 25FM - 25M Cat X-3564 • Serial Cable 25M - 25M Cat X-3574 $ US • Parallel Printer Cable. Suits IBM Compatibles. cat X-8614 24.95ea • NSW • Albury 21 8399 • Bankstown Square 707 4888 • Blacktown 671 7722 • Bondi Junction 387 1444 • Campbelltown (046)27 2199 • Chatswood Chase 411 1955 • Chullora 642 8922 • Gore Hill 439 5311 • Qosford 25 0235 • Hornsby 477 6633 • Liverpool 600 9888 • Maitland 33 7866 • Miranda 525 2722 • Newcastle 61 1896 • North Ryde 88 3855 • Parramatta 689 2188 • Penrith (047)32 3400 • Railway Square 211 3777 • Sydney City 267 9111 • Tamworth 66 1711 • Warringah Mall 905 0441 • Wollongong 28 3800 • ACT • Fyshwick 80 4944 • VIC • Ballarat 31 5433 • Bendigo 43 0388 • Box Hiil 890 0699 • Dandenong 794 9377 • East Brighton 592 2366 • Essendon 379 7444 • Footscray 689 2055 • Fra nkston 783 9144 • Geelong 43 8804 • Melbourne City 326 6088 • Richmond 428 1614 • Ringwood 879 5338 • Springvale5470522 •OLD• Brisbane City 229 9377• Calms 311515 • Chermside 3596255 • Redbank 288 5599• Rockhampton 27 9644 •Southport?~ 9863 • Toowoomba 384300 • Townsville 72 5722 • Underwood 341 0844 •SA• Adelaide City 223 4122 • Beverley 3471900 • St. Marys 277 8977 • Elizabeth 255 6099 • Enfield 260 6088 •WA• Cannington 451 8666 • Fremantle 335 9733 • North Perth 328 6944 • Perth City 481 3261 • TAS • Hobart 31 0800 •NT • Stuart Park 81 1977 ORDER BY PHONE TOLL FREE (008) 22 8810 FOR 24 HOUR DESPATCH TELETEXT for your existing TV set! • Not a kit - it's ready built and tested. Just plug it in! • Uses your VCR tuner to save you$$$. • Hundreds of pages of the latest news, sport, finance, weather, information ... all free! • Also receives "subtitles" or closed captions for hearing impaired. • Easy to use! • Designed and manufactured in Australia, with full service back-up through Dick Smith Electronics. • Infra-red remote control INCLUDED at no extra charge! WHY BUY A NEW$1100 TELETEXT TV? ONLY $3 99 =- At last! Now you can receive Teletext - without going to the huge expense of buying a new Teletext TV! Haven't seen Teletext yet? You're missing out on the latest news, stock exchange and financial information, sport results and TAB information, weather reports and forecasts, even recipes, jokes and much, much more. It comes to you absolutely FREE - courtesy of the Australian Television Network. On a normal TV, it's the little colour flashes you see in the black bars between picture frames when your TV "rolls". Unless you have a Teletext TV or decoder, you don't even know they're there! And don't forget, most stations transmit popular programmes with subtitles for the hearing impaired. This Teletext decoder will let you see subtitles too! Until now, you've had to buy a specially equipped TV to receive Teletext. Now you can buy just the Teletext decoder - and keep your TV set! It's not a kit - it's ready to go. And because it plugs into your video cassette recorder, costly duplication of the tuner section is eliminated. So you save! Isn't it time you had the benefit of Teletext in your home? Cat L-4468 ONLY AVAILABLE FROM VINTAGE RADIO By JOHN HILL Advice to the budding collector Over the last 12 months or so, I have dealt with most of the important aspects of restoring valve radio receivers. At this stage, it would be a good time to look back before going any further. A few additional comments could help those who may be considering taking up this unusual hobby. First, I should point out that one does not have to be an "oldie" well versed in valve technology to be able to collect, repair and enjoy old radios. At 52, I don't consider myself really old and when I started collecting (about three years ago), I certainly wasn't at all knowledgeable about valve technology. For this reason, I have tried to keep things fairly simple. I virtually started from scratch and I know that there is nothing worse than trying to digest information that is overly technical. My first repair My first radio repair was more good luck than good management and I repaired that set without any real understanding of what I did. A timber cabinet with several contrasting timbers was used to house this Operatic of about 1947 vintage. These radios were made in Adelaide. 18 SILICON CHIP This first restoration was on an old Radiola console that "worked" but not very well. A close examination under the chassis revealed two things of interest - a large redback spider and a paper capacitor with split ends. Evicting the redback and replacing the suspect capacitor cured the problems and the set worked quite well from then on. If I had not succeeded with that first repair I would probably have lost interest in vintage radios and found something else to do with my spare time. As it happened, I was able to repair that particular set and became so enthused that I went on to collect and restore many more old receivers. Servicing valve radios involves nothing more than searching for defective components. With my first restoration I was lucky that the problem was obvious enough to be seen. Unfortunately, this is not always the case and some receiver malfunctions can be quite difficult to cure unless one has a good understanding of valve technology. However, in most cases, one does not really need to have an intimate understanding of valve radios to be able to repair them. While such a comment may suggest that you don't have to know what you're doing, the fact remains that a lot of repairs can be made by simple logic, deduction and observation. Just running a check on valve heaters, resistors, chokes and speaker transformers will detect most valve radio problems, as detailed in previous columns. I have kept a logbook on my many repairs, listing the nature of the fault and the eventual cure. This is a particularly good idea for people Vintage Radio Kits & Parts ORPHEIIS *RADIO* Many hours were spent restoring this post-war Philips Radioplayer to as new condition and the effort certainly paid off. This set has a short wave band and performs extremely well. Suppliers of • • • • • VALVES RADIO KITS CAPACITORS RESISTORS BOOKS, ETC. Please send for our free catalogue ORPHEUS RADIO RSD 898 BALLARAT VICTORIA 3352 Ph. (053) 34 2513. Fax (053) 31 3412 FIX-A-KIT Kit Repairs - $1 5 per hour. Normal Rate - $30 per hour. No charge for kits that can't be repaired. 3 month Warranty on repairs. Construction - fixed or hourly rate. 1 2 Month Warranty on Manufactured Kits. Custom Designing, Manufacturing, Large or Small Quantitites. This little 5-valve Astor mantle set is from the early 1930s. Note the ornate timber cabinet and the simple dial markings. who, like myself, have lousy memories. It's good to have such a book for future reference. Dangerous voltages Vintage radio can be a dangerous hobby if you don't know what you are doing. In fact, you are literally flirting with death if you indiscriminately probe around under- neath the chassis of a live 240V ACoperated valve radio. When I started out in this hobby, I had a healthy respect for the underside of any mains-operated set - and still have! So far I have not had a single tingle from a radio set and I intend to keep things that way. I have no desire to get tangled up with either HYCAL INSTRUMENTS Design, Manufacture, Repair of Electronic Equipment. (02) 633 5897 (02) 92 6309 Fax (02) 925 0840 APB /1, 1989 19 An early post-war HMV 5-valve receiver. Once again, many hours of work have restored the Bakelite cabinet to as-new condition, These old sets were capable of good performance. the 240VAC supply or the high tension DC. My advice to the novice enthusiast is to first learn where to find the 240VAC and the hightension DC connections. They are the ones that bite and it is important to know where they are before tinkering. As one progresses from one repair to another and reads up on old valve literature, the mysteries of valve technology will disappear. The main problem when changing from modern radio circuits to valve radio circuits is the big difference in operating voltages. If you are accustomed to solid state circuitry, it's easy to become complacent. In this type of equipment, the primary side of the power transformer (assuming that the set has one) is the only nasty spot that is likely to be encountered. And even then, it will most likely be well insulated. 20 SILICON CHIP This 5-valve Airzone is a classic mantle radio from the late 1930s. This particular set is housed in a Bakelite cabinet and features a rather ornate loudspeaker grille insert. Valve equipment on the other hand demands far greater respect and anyone working on it for the first time will need to be constantly on the alert. Just one moment of inattention could result in a nasty shock. Incomplete sets A problem that sometimes confronts a radio restorer is the set that someone else has tinkered with beforehand. In such cases, the radio may have had a number of components removed or disconnected and unless a circuit is available, there is little hope of the novice repairman knowing what components need replacing and where. These sets often end up in the too hard basket. In such cases, it's best to try to track down a circuit diagram. But above all, the vintage restorer has to be determined rather than super intelligent or good looking. If anyone wishes to restore old radios without previous experience in that field, there's no real reason why they can't. Most will succeed if the desire to do so is there. I would even go so far as to say that, as a hobby, vintage radio is probably a far more enjoyable pastime for the novice than it is for people experienced in electronics. For the novice, everything is a new and exciting experience. On the other hand, a radio-TV serviceman may find that vintage radio is little more than an extension of his everyday work. Collecting Although there are many thousands of old valve radios (both working and not working) to be found, they are getting scarcer every day. With this thought in mind, I spend a good deal of my spare time collecting whatever I can. It will take several years for me to restore This photograph is of an early postwar 5-valve Airzone. Valve radio receivers of this era were of particularly good quality. Buy direct from Australia's leading manufacturer and save on quality AVTEK Modems. A range of 16 internal & external modems . from low priced manual to fully automatic 2400 bps models complete with power supply, instructions and telephone connections. Designed and built in Australia, all Avtek Modems are guaranteed, with service and technical support available direct from Avtek. CALL TODAY ON 008 25 2754 or (02) 888 5333 TOLL FREE SYDNEY RESIDENTS For further information and to see how much you can save on the best modem for your needs. ll&J 14VTEK DATA COMMUNICATIONS (A Member of the NetComm Group of Companies) Another receiver from the early 1930s - a 4-valve Airzone. This style of radio is much sought after by collectors for it has real vintage radio appeal. the receivers that I have so far collected. Whilst it is not hard to locate and buy valve radios, the really collectable ones are difficult to find and it is now almost impossible to obtain old receivers from the mid-1920s era in good condition. These truly antique radios are mostly in the hands of collectors and not many come up for sale at house auctions like they did 20-30 years ago. However, despite the lack of these genuine antiques, there are still lots of interesting and very collectable radios from the 1930s to be had if one looks around. In the past two weeks I have obtained four such sets ranging from 1933 to 1938. All are restorable but only one was in "going" order. Any radio that is half a century old or older must be considered a collectable item. That said, there's nothing to stop you from restoring an early postwar radio if you come across an interesting model. If reader response is anything to go by, there is a lot of interest in vintage radio. Some collectors have been at it for 30 years or more but most, like myself, have only recently joined the ranks. Increasing interest in valve radios has seen the p_rice of old receivers at least triple in the past two years. No doubt, some of the renewed interest has been generated by this column. Interest in vintage radio has been such that, a few years ago, the Historical Radio Society of Australia was formed by a group of keen collectors. The society has attracted world-wide membership and has brought together a number of vintage radio collectors who may never otherwise have met. Next month (and in future columns), we shall get back to the practical aspects of collecting and restoring vintage radios. There's lots of topics yet to discuss on this fascinating hobby. Finally, I have included photographs of some of my radio treasures with this month's column. There is nothing like a picture of a nice old radio to keep interest and enthusiasm high. ~ APRIL 1989 21 Telephone bell monitor/transmitter This simple device plugs in parallel with your telephone. When the phone rings, it broadcasts a sequence of tones to a portable FM radio. By GREG SWAIN & MALCOLM YOUNG Ever wished for a portable telephone extension bell so that you can monitor phone calls from your garden or garage? This new "Telephone Bell Monitor" can be built for around $15 in just a couple of hours. After that, you can listen for phone calls via your FM radio. That way, you needn't pay the high price of a cordless phone and yet you won't miss any calls, simply because you couldn't hear the phone. Inside our new Telephone Bell Monitor is a simple tone generator circuit which is activated each time the phone rings. This tone generator drives a low-powered FM 22 SILICON CHIP transmitter stage which has a range of about 25 metres and can be adjusted to operate anywhere in the 88-108MHz FM band. To use the unit, you simply tune your FM radio to the transmitter frequency and then take the radio with you. You could use a small FM radio slipped into a shirt pocket or even a W alkman-style radio. With this set-up, you no longer have to be in a position to hear the phone directly. When it rings, you'll hear the ring tones via the radio. No batteries are required. Instead the Telephone Bell Monitor is powered directly from the telephone lines. A small plastic utility case houses all the parts, which are readily available. How it works Fig.1 shows the circuit diagram of the Telephone Bell Monitor. It can be broken down into three sections: a bridge rectifier (D1-D4) plus associated power supply components, a tone generator (ICla), and an FM transmitter stage (Ql). Normally, when a phone is "onhook", there is about 50V DC between pins 6 and 2 of the phone lines. In the Telephone Bell Monitor, this voltage is blocked by a 0.47µ,F 630V DC capacitor and so no voltage appears across the bridge rectifier (D1-D4). This means that the circuit is off and so no tones are transmitted. Now let's consider what happens if someone calls your number. When this happens, a 50Hz "ring" voltage of about 70 to 80 volts is applied to the lines, to power the bell circuit. This large AC voltage is fed via the 0.47µF capacitor to the Dl-D4 bridge rectifier. The DC output from the bridge is then regulated to + 10V by ZDl and also charges a 22µF capacitor via D5. Thus, each time the phone rings, + 10V DC appears across ZDl. This voltage is applied to pins 12 & 13 of inverter stage ICld which means that the output at pin 11 switches low. ICld in turn drives paralleled inverter stages IClb and IClc and so pins 4 and 10 switch high. Two things happen when these paralleled outputs switch high. First of all, power is applied to the FM transmitter stage (Ql) which immediately begins operating. Second, pin 1 of ICla is pulled high and this "enables" (ie, starts) Schmitt trigger oscillator stage ICla. ICla generates an 800Hz tone signal to modulate the transmitter stage. Let's follow through and see how the oscillator works. Normally, with no ring voltage, no power is applied to the circuit and so the inputs and output of IC la are all low. If a ring voltage is now applied to the telephone lines, pin 1 of IC la is pulled high and thus pin 3 also goes high. The .015µF capacitor on pin 2 now charges via the 120k0 feedback resistor until it reaches the upper threshold of the Schmitt trigger NAND gate. When this happens, the pin 3 output switches low and the .015µF capacitor now dis- A small on-board trimmer capacitor (at end of pen) allows you to set the transmitter frequency to any spot on the FM broadcast band. The unit should have a range of about 25 metres or more. charges to the lower threshold via the 120kn resistor. The pin 3 output then switches high again and so the cycle continues while ever ring voltage is present on the phone lines. The output from the Schmitt trigger oscillator is applied to the base of Ql via a series 2.2:M:n resistor and .047µF capacitor. As mentioned above, Ql and its associated components function . as an FM transmitter stage. Ll and trimmer 120k capacitor VCl function as a tuned collector load for Ql while the 3.3pF feedback capacitor between collector and emitter ensures that the stage oscillates. Frequency modulation of this stage is achieved by applying a lowlevel audio signal to the base of Ql. So each time ICla generates an 800Hz tone, it modulates the transmitter at this frequency. Drive to the antenna is taken from a tap on Ll while VCl allows the 470pf~ TELEPHONE LINE .001 B EQc 1M VIEWED FROM BELOW TELEPHONE BELL MONITOR Fig.1: the circuit is very simple and includes a bridge rectifier (D1-D4), a tone generator (ICla) and an FM transmitter stage (Ql). When the phone rings, the circuit is powered up and ICla modulates the transmitter with an 800Hz signal. APRIL 1989 23 A standard telephone plug is used to terminate the telephone line leads. Be sure to connect the leads to pins 6 and 2 of the plug (see markings inside). The assembled printed circuit board clips neatly into a plastic utility case. ~ ANTENNA o - VC1 of l 4 6 1 TELEPHONE LINE 100 2 :,; - . il--,'4) ~ ~ 2µ - D5 0 Fig.2: push all the parts down onto the PCB as far as they will go before soldering the leads and take care with polarised components. The 0.47µF capacitor must be rated at 630V DC. transmitter to be set to any frequency in the 88-108MHz FM broacast band. Power for ICl [and thus for the transmitter stage) is derived from the 22µF capacitor at the output of D5, rather than directly from the regulated output of the bridge rectifier. This arrangement has been used to ensure a more stable supply to the tone generator and transmitter stages on each application of the ring voltage. Construction A small printed circuit board coded SC 0120489.1 and measuring 24 SILICON CHIP 0 0 SC01204891 Fig.3: here is the actual-size PC pattern. 69 x 59mm accommodates the circuit components. Note that you must use this board since it incorporates inductor L1 as part of the copper pattern. Fig.2 shows how the parts are mounted on the PCB. You should begin the assembly by installing PC stakes at the three external wiring points. Once this has been done, the rest of the parts may be installed. Push the parts down onto the PCB as far as they will go before soldering their leads and pay particular attention to polarised components. When all the parts are in position, check your work carefully for possible wiring errors. In particular, check for solder bridges and for possible faults in the copper pattern. Note that the 0.47µF input capacitor must be rated at 630V to cope with the ring voltage. Do not substitute a capacitor of lower voltage rating here. A plastic utility case measuring 130 x 68 x 41mm can be used to house the circuit board. You will have to drill two holes in one end to accept the antenna and the phone lead [see photograph). When this has been done, pass the leads through the holes and tie a knot in each just inside the case to provide PARTS LIST 1 PCB, code SC 01204891, 69 x 59mm 1 plastic utility case, 130 x 68 x 41mm 1 telephone plug (Dick Smith Cat. F-511 7 or equivalent) 1 telephone double adaptor (Dick Smith Cat. F-511 2) 3 PC stakes Semiconductors 1 4093 quad Schmitt NANO gate (IC1) 1 BC548 NPN transistor (01) 5 1 N4004 diodes (D1 -D5) 1 1 0V 400mW zener diode (ZD1) Capacitors The Telephone Bell Monitor is simply plugged into the telephone line in parallel with your phone via a double adaptor. When not is use, the unit should be unplugged or you can fit an on/off switch to the unit. strain relief for the solder connections. The PCB can now be clipped into the case and the leads soldered to the PC stakes. Note that the antenna lead should be made about 1.5 metres long, for maximum range. The other end of the telephone line should be terminated in a standard phone plug for connection to the telephone line. Be sure to connect the leads to pins 6 and 2. These are clearly marked inside the plug. Testing Don't plug the Telephone Bell Monitor into the telephone line just yet. Instead, the best way to test the unit is to temporarily connect a 9V battery across ZDl so that the unit transmits a continuous 800Hz tone. Be sure to connect the battery the right way around, with the positive lead to the cathode (banded) end of ZD1. Now tune your FM radio to a vacant spot on the band and adjust trimmer capacitor VCl until the tone is heard. Ideally, you should use a plastic alignment tool for this job to avoid hand capacitance effects. If you don't have an alignment tool, use a screwdriver instead but move your hand away from the PCB after each small adjustment. If the project fails to work, leave the battery connected and check the voltages around the circuit. You should get about 8.4V across the 22µF capacitor and this voltage should also appear on pin 14 of ICld. Pins 1, 4 and 10 of ICl should be very close to the IC supply voltage (8.4V}, while about 0.6V should appear between the base and emitter of Ql. Assuming that everything is OK and you get the tone, remove the 9V battery and plug the unit into the telephone line in parallel with your phone. Now dial 199 and hang up. Your phone will now ring and you can check that the unit transmits a series of tone signals to your FM radio. Note that you may have to adjust the receiver frequency slightly to compensate for the 1V increase in DC voltage to the transmitter stage. That's it - your Telephone Bell Monitor is now ready for work. Before using it, we suggest that you check the range of the unit so that you will know just how far you can wander from the phone. As already mentioned, you should get a range of around 25 metres. 1 22µF 16VW PC-mount electrolytic 1 0 .47µF 630VDC metallised polyester 1 .04 7 µF metallised polyester 1 .015µF metallised polyester 1 .001 µF metallised polyester 2 4 7 0pF ceramic 1 3 .3pF ceramic 1 6-20pF trimmer capacitor (VC 1) Resistors (0.25W, 5%) 1 1 1 1 2.2MQ 1 MD 1 20kfl 47k!J 1 1 0kfl 1 1 k!J 1 100Q Miscellaneous Insulated hookup wire for ant~ na, twin-lead telephone cable,· 9V test battery. Note that the antenna lead should be stretched out to get the best range. Finally, you can fit a small test feature to the circuit if you wish. All you have to do is wire a momentary contact pushbutton switch in series with a 9V battery across the output of the bridge rectifier. By pushing the button, you can then check your radio's tuning and, if necessary, adjust it to the correct frequency. ~ Acknowledgment: our thanks to Alan Lackey, ldaline Street, Collaroy Plateau , NSW for the circuit on which this project is based. APRIL 1989 25 AT LAST! A Cheap Stepping Motor fcOMPUTERLEAD BARGAINs' I I APRIL ONLY $9.95 SAVE $10.00 I • 25D Male to 25D Female 1.Bmt Cat. PL-0055 Normally $19.95 · \ I SAVE 50% on normal price Once again we have purchasetl a bulk shipment of HIGH QUALITY Philips brand 4-phase Unipolar Stepping Motors! The manufacturer was forced to sell this stock FAA BELOW his cost and we can pass these massive savings on to you! The motor, Philips #9904 112 06001 is a high performance bidirectional unit featuring a 7°30' step (48 steps per rev) with 40mNm max working torque. Full data is provided. INCLUDED IN THE COST is a Sprague UCN4202 4-phase stepper motor driver chip. This will drive the motor directly from logic and a nominal 1'll/ supply. Once again full data on the chip is included. The current WHOLESALE cost of the motor ONLY from Philips is over $75 +20% sales tax i.e. around $90. You can purchase the motor and driver IC in 1-off from us for this month only $59! That makes the stepper under $50! Limited Quantity. Cat YM-2700 • 25D Male to 25D Male Normally $19.95 1.Bmt Cat. PL-0056 APRIL ONLY $9.95 SAVE $10.00 '1 • Centronics Plug to 25D Male 1.8mt Cat. PL-0054 Normally $18.95 I I APRIL ONLY $9.95 SAVE $9.00 I $59 Stepper Motor and UCN 4202 chip UCN chip available separately $10 (Cat. ZK-8842) Philips SAA 1027 4-phase driver IC (designed especially for the motor) Cat ZK-8843 $15. Data included with SAA 1027. / ~ ,..-·· - ... ---•;;: •'·}•:,J ... 24 PIN CENTRONICS TYPE CONNECTORS J"lf(/£ _I ~·i J . WIRE WRAP WIRE BARGAIN Another surplus stock buy. Amphenol series 57 (same as Centronics 36 pin but with only 24 pins). Save a fortune over normal prices. • Solder plug with metal backshell Cat PP-0900 (100 available) 3.5" length Black Cat. WW-4310 Green Cat. WW-4314 Blue Cat. WW-4312 Red Cat. WW-4316 Packsof100NORMALLY$5.95 ONLY $ 5.5" length Blue Cat. WW-4332 Red Cat. WW-4336 NORMALLY $6.95 Packs of 100 ONLy 3 •95 • Solder Socket with Metal Backshell Cat PS-0901 {100 available) $4.95 • IDC Plug Cat. PP-0902 (250 available) Parramatta Gore Hill • IDC Socket Cat PS-0903 (300 available) Hurstville York Street Springvale National Linear Data & Applications Set You get National Linear Data books Vol 1, 2 & 3 and the ALMOST-IMPOSSIBLE-TO-GET latest printing o( National Semiconductors -Linear Applications. {Please note that Linear Applications can't be sold seprately). Cat BN-4000 4 BOOKS FOR ONLY $79.95 Melbourne City Buranda Old Sat till 4pm, Thurs till 8.30pm Sattill 4pm Thurs till 8.30pm Thurs till 8.30pm Sat till 2pm, Fri till 8.30pm Fri till 8.30pm Thurs till 8.30pm PIEZO REVERSING BUZZER Extremely lo~d (115dB) piezo buzzer which is mounted on a metal angle bracket Ideal as a rENersing warning on vehicles or just an intermittent beeper. Draws 1OOmA. Size 58 dia x 38mm deep plus bracket 50mm. These would normally be worth about $1 B. Cat. AB-3443 SPECIAL AT $9.95 METEX DMM BARGAIN Save $40 on this discontinued 3.5 digit unit with transistor and capacitance testers included. Features • 0.5" high digits • High quality probes • LED and buzzer continuity • Precision thin film resistors for long term stability • CMOS logic • 1,000 • 2,000 hours battery life The alternative to the gas-type portable irons. Uses 2 x CNi Cads • Meter protection fused and they can be recharged in the 'Duck'. Tip retracts back into the • Complete with battery and spare body of the iron when not in use. Named after the famous toilet fuse cleaner as it looks the same. Supplied with one tip and one spare • Floating decimal point plus Slll\lll quantity of solder. · A Dimensions: Length (0/A) 210mm x 30(W)mm. Charger not supplied. ..• Vi~~ ~~;~i!se FOR MORE INFO SEE 1989 CATALOGUE. ., Cat. QM-1540 Cat TS-1430 SEE 1988 CATALOGUE FOR Extra tips Cat. TS-1432 $4.95 " SPECIFICATIONS. WAS $129 Battery Powered Cordless ·Soldering Iron "TOILET DUCK" $19 95 NOW ~NT.V ~AQ SAVE $40 Limited Quantity VERBATIM DISKS AT UNREAL PRICES Compare our prices with your normal supplier. Description 1-9 Boxes 10+ Boxes 3.5" 1S/2D Cat. XC-4720 $39.95 $37.95 3.5" 2S/2D Cat. XC-4721 $46.95 $43.95 3.5" 2S/HD Cat. XC-4722 $99.00 $89.00 5.25" 1S/2D Cat. XC-4725 $22.00 $21.00 5.25" 2S/2D Cat. XC-4726 $26.00 $24.00 5.25" 2S/HD Cat. XC-4727 $41.00 $39.95 DIGITAL AUTO TUNE UP METER .Measures RPM, dwell (on 8 6, 5 & 4 cylin11er cars). AC volts, DC volts, points rsistance. diode check and even ohms! FOR FULL SPECIFICATIONS SEE 1988 CATALOGUE Cat. QM-1573 Normally $139.50 APRIL ONLY $109.50 SAVE $30 JAYCAR - LEADING IBE WAY IN NEW PRODUCTS Deluxe Black Rack Cabinets with Handles I/,£ •~,t ... -('r-L- QUALITY AN D DESIGN FUNCTIONABILITY AT A DOWN TO EARTH PRI CE- A JAY CAR DIRECT IMPORT PROD UCT Jayca r proudly announce a range of 5 beautiful black. direct ~ D import rack cabinets. Give your equipment a real 1st class appearance. All aluminium construction, removable top and bottom panels, black finish with • high quality brushed anodised front panel. Handles and rubber feet supplied , along with all screws. nuts. etc. to assemble. Individually cartoned. suppli ed in fl at pack. These cabinets really ··... I / look the part and check out the 111N prices compared to other ····... ../ ones. ······.......····,... A B C D E Each 5+ HB-5380 255 73 177 305 75 $39.50 $36.50 HB-5381 353 98 203 401 100 $49.50 $46.00 HB-5382 429 62 203 481 69 $49.50 $46.00 !;it 292 481 100 $65.00 $61.00 1((1 HB-5383 429 95 HB-5384 429 122 292 481 126 $75.00 $70.00 fi' ft f I Jaycar Soldering Kit Designed for general purpose soldering. This kit includes a 30 watt 240 vol t sol dering iron, a quali ty meta l stand with sponge, a length of solder and a roll of solderwick. Cat. TS-1 650 $29.95 'i jJ ·: . ,lf'I Thinking about investing in a VIFA speaker kit? -----=~ ·U , ·n U· . Let Jaycar tempt you into making that decision NOW and SA VE UP TO $200 PER PAIR. All our •lores hsve the new upgraded Vifs ki16 on demon.trstion so drop in and have a listen. Remember, you will pay about twice as much for •imi/ar pre--buill, Imported speaker• when, in lac~ they will probably have Vila apeskem in them anyway. See ourt989 catalogue for full detsila. (Demon.tration •peaker• are not at Concord). :(With JAYCA RDIGl"fALM ULTmlETER' almost everything - SAVE $50 over others) I LOOK AT THESE FEATURES • 34 ranges - 3.5 digit LCD display • High impact yell ow case ~ .. . • Small size - only 133 x70 x30mm • 1Oamp AC and DC. DCV > 1% worst • Diode tester - continui ty buzzer • Frequency counter 1OHz - 200kHz • Built-in 20MHz logic probe • Capacitance tester 1pF - 20µF • Tilting Bail - Sa fety test leads • One hand operation with unique feature where probes can mount into either side of the case • 3 month warranty Cat. OM- 1400 SA-130 3-way kit complete with cabinets and crossovers . 130W RMS power handling. Cat. CS-2485/CB-2467 I I I I SAVE I $200 I ONLY$999 I APAIR $99.95 : SA •1OQ 2-wayklt complete with cabinets and crossovers . · 1OOW RMS power handling. Cat. CS-2460/CB-2482 , Jaycar Soldering Iron Ideal for the hobbyist and handyman. Our lowest price 240 volt quality iron has a stainless steel ba rrel. 30 watt. Cat. TS-1 450 $16.95 ------- SAVE $100 Ultrasonic Air Humidifier CREATE YOUR OWN CUMATE IN YOUR ONLY $699 OFFICE OR HOME ECONOMY DIGITAL MULTIMETER Digital mul timeter at an analog price t • 3.5 digit LCD di splay • 20 ranges • Diode chec ker • DC 10 amp, 1000V, 0-20M ohm, etc. • 1500 hour battery life • One hand operati on with .unique feature where prooos can mount into either side of the case • Til ting bail • Safety test leads • 3 month wa rra nty Cat. OM- 1410 $59.9 ~ Features • Cutout switch when water runs out • Generous 6.75 litre water tank • Ultra qui et opera tion • Adjustable intensity control • Adjustable humidity control • Air filter included • Humidifies up to 4,000 cubic feet Specifications • 40 wa tts • 240V AC power source • Humidity control 30 - 90% • Dimensions 375(L) x 150(W) x 290(H)mm Cat. YH-5500 WAS SELLING FOR $149 in 1986 NOW ONLY $99.50 SA-70 2-waykit complete with cabinets and crossovers. 70W RMS power handling Cat. CS-2471/CB2472 SAVE $50 ONLY$449 APAIR kit with cabinets and crossovers. 30W RMS.power handling. Cat. CS-2450/CS-2452 SAVE $30 ONLY $369 A PAIR Automatic Telephone Diverter NEW MooEL FoR 19s9 This device will divert an incom ing call to. say, an unattended office, surgery or home, to another location. (Two exchange lines are required). The unit will divert EITHER of the incoming lines. Supplied with 240V plug adaptor, instructions and telephone leads. Double adaptor Cat. YT-6020 $4.95 may be required. Measures 190(W) X 1l O(D) X 35(H)mm. Cat. YT-6510 $249 240/ll0V Stepdown Transformer Bargain Jaycar has secured a quantity of fully enc losed 2SOVA - 240/ 1lOV stepdown transformers. Each unit has a generous 1.7m long inlet (240V) cord with 3 pin mains plug. The 11 0V side has a cord 0.5m long. The tra nsformers are brand new and loca lly made and measure 1lS(H) x 148(D) x 95(W) (not including inlet/outlet cords). Weight is 5.3kg - so $6.00 extra postage appli es over and above our normal P&P charges. Brief Spees: 240V input SOHz 1.14A max 110Voutput SOHz 2.17A max All power wiring enclosed . ONLY $99 NORMALLY WORTH $199 Cat. MS-1 090 Hi Guys! (Only $20 dearer than our 12SVA unit which does not have enclosed wiring). PUBLIC NOTICE The 1989 Jaycar catalogue was inserted In the March issues of 'E lectronics Aust ra lia' and 'Si licon Chip' magafil1es. The Issues of these magazines that were sent to Dick Smith Electronics had t he catalogues with them. It api,ears that the same issues were either sold by DSE or given gratis DID NOT contain a Jaycar cata logue. If you received a copy of 'EA' or 'SC' for March from DSE and it did not contai n a Jaycar catalogue , please ca ll in to any Jaycar store for a FREE COPY of t he catalogue. Jaycar would like to take ''lis opportunity to pledge to our customers that all magazines sold by us contain ALL the material supplied by the magazine publishers inc lud ing competitors cata logues . We are not frightened of competition! Regards, Gary Johnston.M anaging Director, Jaycar Pty Limited . SAVE UP TO AN AMAZING 200 HUNG CHANG 20MHz CRO . · --, .::, -------..! -.:_ •· · .. . . · · ·• - CRO • NORMALLY $899 Cat. OC-1900 NOW ONLY $719 SAVE $180 PROBES (TWO} t4ORMALLY $9 NOW ONLY $79 for 2 SA VE $20 Cat. OC-1902 OPEN AN ACCOUNT WITH JAY CAR Minstrel 2-30 Speaker Kit Jayca r is now accepting account applications from all established compa nies who can ex hibit good trade references For application detail s see our store ma nagers or phone Ref: Silicon Chip Feb. '89 This is a co-operative speaker project between Si licon Chip and Jaycar. Using an 8' woofer and a dome tweeter with pre- bu ilt crossover un it the system has been acclaimed for its superb sound reproduction. The cabinets measure 490: H) x 303(W) x 2901D)mm. FOR FURTHER INFORMATION SEE OUR 1989 CATALOG UEAVAILABLE NOW I (02) 747 2022 SALVAGE SOME CASH Turn your surplu s stock into cash. Jaycar will purchase your surplus stocks of com ponents and equipment. CALL GARY JOHNSTON OR BRUCE ROUTLEY (02) 747 2022 Pair of speakers and Crossovers Ca t. CS-2540 Cabinets (pair) Ca t. CS-2542 $149 $129 PURCHASE BOTH SPEAKERS AND CABINETS TOGETHER AND PAY ONLY $269 Well. the =talogue·s been out tor a month now and judging by how busy we have been you like it! Please keep up the mail orders. While we are getting l ots ot mail the bos.s leaves me alone. (There's nothing the boss likes more than looking at the mail in the morning. I mean it!) Anyway , we got back trom Melbourne O.K. He hasn't been back since . As a matter-Of-tact he's been at work a fair bit lately. Must'nt have had any better otters. Nylon Knickers. You wouldn't believe this. b u t the other day the boss came in With a box FULL ot cotton undergarments. Knickers to be precise. You should have seen them! He must have bou ght them trom a Famine Reliel Opportunity shop! He handed them out to all of us in kits. mail orders and the warehouse. All the ladies in the p lace got two pairs. (At least he didn't insist on fitting them on us). He had been reading a report in the Sydney Daily Mirror (Feb 8. 1989) which claimed that n y lon knickers =uld generate up to 20,000 volts! All he =u!d think about was the micro-: zaps that we could give to his microchips. • Thankfully most ot the ladies told him where to ·, stick his knickers. It they were going to get com pany 'Reg Grundies· they had to be silk and RED. That slowed him down. He is now seen spraying anti-static everywhere. Not a stray volt to be seen. I still get a charge out of working here thoughJ NEW KITS. April is a real= butt month. There's the Auxiliary Brake Light Flasher (re!: Silicon Chip April). It will drive a rear parcel shell m ounted brake light and cause it to flash when you hit the anchor. Great at $17.95 - but it doesn't include the lighU And the two Electronics A ustralia kits for April. One is a Brake Lamp M onitor. This gadget warns you it your brake lights have blown. Only $24.95 -cheaper than getting booked! And the other project turns your m ultimeter into a tacho/dwell (whatever that means!) meter. Helps keep your car in tune. (I w onder it it works on old boytriends?) See our ads for more into! Finally, I'm sorry to say it but this will be my last column for a while. The bos.s has decided to use this space to flog more products. (I really think h e doesn't like being told on). Anyway , until then. see ya! NEW KITS FROM JAYCAR Telephone Bell M onitor /Transmitter Ref: Silicon Chip April 1989 This kit simply plugs in parallel with your telephone. When the phone rings, it broadcasts a sequence of tone signals to a portable FM radio. You can buy a cheap portable radio for around $20 to act as a receiver, that's far cheaper than a kit would cost. Kit includes PCB, box, telephone plug and all specified components. Cat. KC-5048 $16.95 Auxiliary Brake Light Flasher Auto Tune Up Adaptor Ref: Silicon Chip April 1989 Reduce your chance of a rear end collision by building this simple lamp flasher kit. It drives an auxiliary brake lamp mounted on the rear parcel shelf. Kit includes PCB, box and all specified components. Cat. KC-5049 $17.95 1/3 Octave Graphic Equaliser Ref EA April 1989 Turn your multimeter into a tacho/dwell meter with this simple adaptor. It's easy to build and may be calibrated for 4. 6 or 8 cylinder petrol engines Any multimeter above 20k/l/ will do, analog or digital. Kit includes PCB, die cast box and all specified components. Cat. KA-1716 $ 29.95 $24.95 . SEE THE JAYCAR 1989 CATALOGUE FOR FULL TECHNICAL SPECS $239 TTL •ANAL CONTINUITY TESTE R Refer EA Feb 89 This all-singing, all-dancing continuity tester kit features three audio tones. operation over six decades of resistance. auto-polarity reversal. and an ambient current so low, it needs no ON/OFF switch. Kit includes PCB, box and all specified components. Batteries extra (Cat. SB-2369 $435 for 2 Alkaline) PCB SHORT ,. $55.00 "Beat Me" Metronome Size: 130 x 68 x 41 mm ~~~' • ;LI ~ , - - • MasterCard. ~ PARRAMATTA CONCORD HURSTVILLE $29.95 HEAD OFFICE MAIL ORDERS POST & PACKING 115 Parramatta Road Concord 2137 P 0. Box 185 Concord 2137 ~o 9 Telephone (02) 747 2022 HOTLINE (02) 7471888 $25 $49.99 $ 4.50 Telex 72293 FOR ORDERS ONLY $50 $99.99 $ 6.50 10 _F_A_CS_I_M_IL_E~(0_2~)_7_44_0_7_6_7_ _ _ _T_O_L_L_F_R_E_E~(_00_8~)0_2_2_88_8_ _o_vE_R$__0_ _s_10_.o_o_ _~ MAIL ORDER VIA YOUR ff ROAD FREIGHT ANYWHERE IN AUSTRALIA $13.50 L--------------------------------------' SYDNEY • CITY 117 York St. (02) 2671614 · I Cat. KA-1714 i~li ig~ - VISA - This unusual project is actually a metronome that has its rhythm set by simply tapping the unit at the desired rateu can tap it with a drum stick, pencil - even your fingernail 4 times. and the "Beat Me" mimicsate at which it was tapped indefinitely- so simple! The Jaycar kit includes case speaker and all electronic components. It runs on a 9V battery (not supplied). $22.95 1 ..._ Cat. KC-5047 Cat. KC-5046 Refer EA Feb 89 This simple kit will help you locate shorted tracks on printed circuit boards by means of a varying audio tone. It's easily built and much cheaper than commercial units. Cat. KA-1712 ~ =:-i~~:=~=~===~~=-=~~=~~==~~ .: -·.·- ::::: =-~ ,.. ........... _ ,,. . _,........ _... ___ ... ......~~;:_:................... Refer Silicon Chip Jan 89 A line filter kit for your computer which incorporates an effective filter for mains borne interference and a varistor to clip dangerous spike voltages. Kit includes PCB, box (HB-5446) 4 mains sockets and all specified components. $19.95 Cat. KA-1710 . Refer Silicon Chip Feb 89 Great NEW kit. Will measure the gain of a transistor. test NPN, PNP and power transistors. PLUS. by trial-and-error, you can identify BCE on an unmarked device. Kit includes PCB, box and all specified components. $49.95 BEEPO -.:.-~--------BETA TESTER Refer EA Feb 89 This kit will allow you to use an analog RGB colour video monitor as a CGA colour monitor for your IBM PC or compatible. Kit includes PCB, box, panel, D sockets and plug and all specified components. Cat. KA-1711 Ref: EA April 1989 This device will warn you if your vehicles brake lamps aren't working as they should - hopefully before another motorist rams into your rear end. Kit includes PCB, box and all specified components including 12V bezel. Cat. KA-1715 ~ Ref: Silicon Chip March 1989 TOTALLY NEW DESIGN - STUNNING AUDIO PERFORMANCE .. I I . Jaycar, along with Silicon Chip have taken the best features of the 28 band graphics and ····....... I . •····/ incorporated them into this TOTALLY NEW ELECTRONIC DESIGN which-features VASTLY ···... / SUPERIOR audio performance to our old graphics. Apart from the 4 extra bands (which now ··./ extend from 16Hz to 20kHz) the new 'Studio Series' graphic features radically new slide pots, especially made for the project. Mounted in a standard 19' 2 unit configuration, and power directly from mains. Cat. KC-5050 Car Brake Lamp Monitor Mon-Fri 8.30 . 5.30 Thurs 8.30 pm· Sal 9 • 12 355 Cl>J!ch St (Cm. Viclona Rd) (02) 683 3377 Mon-Fri 9 • 5.30 Thurs 8.30 pm· Sat 9 - 4pm 115 Parramatta Rd (02) 745 3077 · Mon-Fri 8.30 · 5.30 · Sat 8.30 · 12 121 Forest Rd (02) 570 7000 · Mon-Fri 9. 5.30 Thurs 8.30 pm· Sat 9 12 GORE HILL 188 Pacific Hwy cnr Bellevue·Ave (02) 439 4799 • Mon-Fri 9 • 5.30 Sat 9. 4pm BURANDAQLD 144 Logan Rd (07) 393 0777 Mon-Fri 9 · 5.30 Thurs 8.30 • Sat 9 -12 MELBOURNE-CITY Shop 2, 45 A'Beckett St City (03) 663 2030 Mon-Fri 9 · 5.30 Fri 8.30 • Sat 9 - 12 SPRINGVALE VIC 887-889 Springvale Road Mulgrave (03) 547 1022 NrCnr. Oandenong Road Mon-Fri 9 • 5.30 Fri 8.30-Sat 9. FLASHER CIRCUIT FOR AUXILIARY BRAKE LIGHTS Reduce your chances of a rear-end shunt by building this simple brake lamp flasher circuit. It drives an auxiliary brake lamp mounted on the rear parcel shelf. By BOB FLYNN & GREG SWAIN Auxiliary brake lamps mounted on the rear parcel shelf are all the rage these days, especially in the major cities. Because they are mounted more or less at eye level, they are much more visible than conventional brake lights and so can significantly reduce the chances of a rear end collision. Although some of the latest cars feature an auxiliary brake lamp as standard (eg, some Honda models), most devices fitted to cars are aftermarket ''add-ons''. These devices are available for about $10 (or less) from stores such as K-Mart and Target (or from auto-accessory shops) and are easily installed. All the motorist has to do is mount the brake lamp on the rear parcel shelf and connect it to the existing brake lamp wiring in the boot. Other units, like the one featured here, come with a self-adhesive mounting surface so that the unit can be affixed directly to the window glass. The angle of the red lens surface can then be set for best visibility by undoing a screw and rotating a small knob on the side of the unit. Making it flash By adding the simple flasher cir220 100 + 16VWr AUXILIARY BRAKE LIGHT 4.7M 4.7M IC1 555 0.15:r. .,. 0.33! 01+ . 0.47! .,.. ~ BCE SAFETY BRAKE LIGHT FLASHER Fig.1: when power is first applied, 555 timer IC2 drives Darlington transistor Ql to flash the auxiliary brake lamp. After about 2 seconds, pin 3 of monostable stage ICl goes low and stops IC2 from oscillating. The lamp then stays on continuously. 30 SILICON CHIP cuit described here, you can make the auxiliary brake lamp even more eye-catching. A flashing lamp is much more easily seen than a lamp which is on continuously whether in daylight or at night time. Our flasher circuit can either be added to an existing auxiliary brake lamp or used in a new installation. The original car brake lamps will be unaffected by the flasher circuit. The circuit doesn't flash the brake lamp continuously though. That would be too annoying for the driver behind in bumper to bumper traffic. Instead, when you first apply the brakes, the Brake Lamp Flasher quickly flashes the auxiliary brake lamp five or six times. After that, the auxiliary lamp stays on in the conventional fashion for as long as the brake pedal is depressed. The brake pedal must then be released for about 1.7 seconds (or more) for the flasher circuit to resume operation. If, on the other hand, braking is reapplied inside the 1.7 second period, the auxiliary brake lamp will simply turn on and remain on until the brakes are released. This delay time makes the light much less annoying for the following driver. About the circuit Two 555 timer ICs and a BD645 Darlington transistor form the basis of the circuit. Fig.1 shows the details. In practice, the two 555 timers (ICl and IC2) function quite differently. ICl is wired as a monos t able timer, while IC2 operates in astable mode. Let's ex- PARTS LIST 0 1 PCB, code SC051 0489 1 , 73 x 55mm 2 2-way PC-mounting terminal blocks 1 plastic utility case, 130 x 68 x 41mm 1 T0-220 mica washer and insulating bush 4 1 0mm PC standoffs 1 5mm rubber grommet +12V FROM BRAKE LIGHTS--411a AUXILIARY ---:-111-1+,,,.Jl:'J BRAKE LIGHT-..:.tli-lli. EARTH TO CHASSIS Fig.2: here's how to install the parts on the PCB. Be sure to install the two ICs the right way around. The Darlington transistor (Ql) mounts underneath the board (see Fig.3). plain those two terms before we go any further. A monostable timer is one that produces a single pulse output of predetermined time. For example, a one-second monostable is a circuit that produces a single pulse one second long. An astable timer is a freerunning oscillator with an output which alternately switches high and low. Now let's see how the circuit works. When power is first applied (ie, the brake pedal is depressed), pin 3 of ICl goes high and turns on Q1 The PCB is mounted on the aluminium lid of the case to provide heatsinking for the Darlington transistor. You can buy the auxiliary brake lamp from auto accessory shops or from stores such as K-Mart and Target. and the auxiliary brake lamp. IC2 then begins oscillating with its pin 3 output switching alternately high and low at about 5Hz. In turn, this switches Q1 on and off at about five times a second to flash the auxiliary lamp. · ICl controls the time for which IC2 can oscillate and therefore flash the lamp. By functioning as a monostable its output at pin 3 is initially high and stays high for a time determined by the 4.7MO resistor and 0.33µF capacitor at pin 6. This time period is 1. 7 seconds, after which pin 3 goes low. This then pulls pin 6 of IC2 low via Dl. Therefore after 1.7 seconds, ICl stops IC2 from oscillating and the brake lamp stays on continuously Semiconductors 2 1 1 1 555 timer ICs (IC1 , IC2) 8D645 Darlington transistor 1N4148 diode (D1 ) 15V 1 W zener diode (ZD1) Capacitors 1 1 1 1 2 1 OOµF 16VW electrolytic O.4 7 µF metallised polyester 0.33µF metallised polyester 0.15µF metallised polyester .O1µF metallised polyester Resistors (0 .25W, 5%) 2 4.?MO 1 1 MO 1 1 OOkO 1 1k0 1 220 Miscellaneous Cable ties, automotive cable, automotive connectors, machine. screws and nuts, split washer,' star washers. APRIL 1989 31 Fig.3: this diagram shows the mounting details for the BD645 Darlington transistor. The metal tab of the transistor must be isolated from the lid using an insulating bush and mica washer. 0 Ho + t_.i -$- I 0 + + 29 ALL HOLES 3.9mm DIA. 0 31 DIMENSIONS IN MILLIMETRES Fig.4: here is the drilling pattern for the metal lid. Drill all holes to 3.9mm (ie, 5/32-inch). When pow&r is removed from the circuit (ie, after you take your foot off the brake pedal), the 0.47 µ.F capacitor needs time to discharge via the 4. 7MO resistor. If it is not almost completely discharged at the next brake application, pin 2 will inhibit the monostable function. This means that pin 3 will remain low and pin 6 of IC2 will also be held low via D1. Thus, IC2 will be prevented from oscillating and so the auxiliary brake lamp will light up without flashing. In practice, for brake applications greater than about two seconds apart, the auxiliary brake lamp will be allowed to flash. Conversely, for rapid brake applications less than two seconds apart, the auxiliary brake lamp will not flash but will come on at the same time as the main brake lamps. Power for the circuit is derived from the + 12V rail which runs to the main brake lamps (ie, after the brake lamp switch). A 220 resistor and 100µ.F capacitor decouple the supply while zener diode ZDl clips any supply line spikes to + 15V to protect the 555 timer ICs. Note that since power for the circuit comes from the brake lights, no supply voltage will be present in the circuit unless the brakes are applied. Building it Use your multimeter to check that the metal tab of Qt is correctly insulated from the metal lid after the assembly has been bolted together. The PCB is mounted on four 10mm-long standoffs. while ever the brake pedal is depressed. Resetting ICt As noted above, we don't want the lamp to flash if the brakes are released and quickly reapplied, to avoid annoying the driver behind. This is taken care of by the trigger 32 SILICON CHIP function at pin 2. At the first power application, pin 2 is held low by the 0.47 µ.F capacitor. This allows the monostable function just described to take place. But while the 0.33µ.F capacitor is charging, the 0.47 µ.F capacitor at pin 2 is also charging via its associated 4. 7MO resistor. Construction is straightforward. All the parts are mounted on a small printed circuit board (PCB) coded SC 05104891 and measuring 73 x 55mm. This is housed in a small plastic utility case with a metal lid which acts as a heatsink for the BD645 Darlington transistor (Ql). Install the parts as shown on the layout diagram of Fig.2 but don't mount Ql at this stage. It's best to install the resistors, diodes and the two ICs first and then move on to the capacitors. Be sure to mount the two ICs the right way around. Pin 1 of an IC is always adjacent to a dot or notch in one end of the body moulding (see Fig.2). The two diodes and the 100µ.F electrolytic capacitor are also polarity conscious and must be correctly oriented. Check the resistor values on your digital multimeter if To identify the brake lamp lead on double-filament lamps, connect a multimeter between one of the lamp terminals and chassis. The meter should read about + 12V when the brake pedal is pressed and OV when the pedal is released. you have difficulty reading the colour bands. A PCB-mounting screw terminal block is used to terminate all external wiring connections to the PCB. Four-way terminal blocks are not reaily available so we suggest that you simply use two 2-way blocks side-by-side. Since more than 1.5 amps flows through the BD645, it must be attached to the metal lid of the case for heatsinking. Fig.3 shows the mounting details. To install this transistor, first bend the leads at 90° at the point where the leads suddenly narrow. The transistor should then be soldered in position so that the ends of the leads just sit flush with the top surface of the board. Fig.4 shows the drilling details for the metal lid. Mark out and drill all holes to 3. 9mm diameter (5/32-inch). Once this has been done, carefully deburr all holes us- +0 + SC05104891 0 Fig.5: full-size artwork for the printed circuit board. ing _an oversize drill. In particular, make sure that the mounting hole for the BD645 is free of metal swarf. A TO-220 mica washer and insulating bush must be used to isolate the metal tab of the BD645 from the heatsink. Smear all mating surfaces with heatsink compound before bolting the assembly together. It may be necessary to trim the length of the insulating bush so APRIL 1989 33 This auxiliary brake lamp is affixed directly to the window glass but some units are designed for mounting on the rear parcel shelf. + 12V FROM BRAKE LIGHT SWITCH CRIMP CONNECTOR '-sTOP LIGHT Fig.6: once you've identified the brake lamp lead, it can be connected to the + 12V flasher lead using an automotive crimp connector. Don't forget to connect the earth lead to chassis. that the screw can be tightened correctly. Don't forget the split washer under the nut. If you leave it out, the nut will eventually shake loose. The PCB can now be secured to the lid using four 10mm standoffs, machine screws and nuts, and shakeproof washers. After that, it's simply a matter of drilling a hole in one end of the case to allow for cable entry. A rubber grommet should be fitted to this hole to prevent the cable from chafing. Installation To ensure proper operation, the 34 SILICON CHIP brake lamp flasher should be connected as shown in Fig.6. Begin installation by mounting the auxiliary brake lamp inside the vehicle according to the manufacturer's instructions. Once this has been done, you can mount the flasher circuit under the rear parcel shelf. In most cases, it can be secured using two self-tapping screws through the rear of the case. Now run the power cable from the auxiliary brake lamp down behind the back edge of the parcel shelf and route it inside the boot to the flasher circuit. Pass the cable through the rubber grommet and trim the two leads before connecting them to the terminal block. Nylon cable ties or electrical tape can be used to secure the cable in position. If your car is a station wagon or a hatchback, the auxiliary brake lamp can be mounted at the top of the rear window and the power ea ble run along next to the window moulding. In some cases, it may even be possible to pull back the moulding and tuck the cable beneath it. The earth lead can now be connected between the terminal block and chassis. To do this, connect the earth lead to an automotive eyelet terminal, then secure it to the car body using a self-tapping screw. The + 12V power lead must be run from the flasher circuit to one of the tail light assemblies. If you can, route this lead alongside the existing wiring loom. Ideally, this lead should be the same thickness as the car wiring, as this makes for a more reliable connection when using a cable squeeze connector. Double filament lamps On most cars, double filament globes are used for the tail and brake lamps. You can easily identify the brake lamp lead by using a multimeter switched to a voltage range. Just connect the meter between one of the lamp terminals and earth while someone else presses the brake pedal. An automotive squeeze connector is the best way of connecting the flasher lead to the brake lamp lead. A suitable connector will usually be supplied with the auxiliary brake lamp, along with cable ties and an eyelet terminal and self-tapping screw for the earth connection. Finally, test the installation thoroughly. The auxiliary brake lamp should only come on when the brake pedal is pressed. Check that the lamp flashes five or six times and then remains on until the brake pedal is released. If the auxiliary lamp comes on when the parking lights are switched on or is activated when the turn indicator is used, the flasher circuit is conn1;Jcted to the wrong lead at the tail light assembly. It High Performance In Your Shirt Pocketl "S:!:8~'.~w 3 l /2 digit LCD Display Ranges Max Res Accuracy Vdc Vac Ade 100µV 1mV 1001-tA 10mA 100µA 10mA 0.1Q 200mV-1 kV 2V-750V 200mA 10A Aac 200mA 10A Ohms 200Q-2MQ Display also has Low Battery & Over-Range Indication 0.5% + 1dig 0.75%+5dig 0.75%+ 1dig 1.5%+5dig 1%+5dig 2%+ ?dig 0.75%+1dig Built In Diode Check, Lo-Power Ohms & Continuity Test Beeper Memory Function for Relative Readings (DM6235 & DM6335) •QOc/4c /Lori ~ .,, Autoranging -~ Manual Ranging Over-Ride (DM6235 & DM6335) I "~ Ft~ ;7 One Year Warranty Hold Reading Function (DM6335) l0A Range Automatic Current Limiting Overload Protected to l 000Vdc/750Vac $69.00* $79.00* Look At The Low Pricesl DM6135 Autoranging 3 1/2 digit 10A ac/dc DM6235 As above with Memory function and Range Hold Prices include 9V Battery and High Quality Silicon Rubber Test Leads with Screw-On Alligator Clips DM6335 As above with Data Hold l0MQ Input Impedance Got ta • G (! t ta • ,G 0 IdSta $89 • 00* You 've Gotta Getta Goldstar from : Supported & Serviced Australia-wide by Elmeasco Instruments Pty Ltd Dealer enquiries welcome. Call (02)736 2243 Recommended prices only including Sales Tax A.C.T. John Pope Electrical 80 6576 • J Blackwood & Sons 80 5235 • George Brown 80 4355 N.S. W. George Brown 519 5855 Newcastle 69 6399 • Ames Agency 699 4524 • J Blackwood & Sons Auto-Catt Industries 5451322 • D:G. E. Systems (049) 691625 • WF.Dixon (049)69 5177 • Macelec (042) 291455 • Newtek (042) 27 1620 • Novacastnan Electronic Supply (049) 62 1358 • Obiat Ply Ltd 698 4776 • David Reid 267 1385 • Dig1tel 709 6511 • Geoff Wood 427 1676 N.TERRITORY J Blackwood & Son (089) 84 4255, 52 1788 • Thew & McCann (089) 84 4999 QUEENSLAND Auslec 85_41661 • George Brown 252 3876 • St Lucia Electronics 52 7466 • L.E.Boughen 3691277 BAS. Aud1otrorncs 844 7566 • Colourview Wholesale 275 3188 • E.C.Q. Electronics 376 5677 The Electronics Shop (075) 32 3632 • Thompson Instruments (Cairns) (070)51 2404 • Solex (Townsville)(077) 72 4466 • Xanthos Electrical (079) 27 8952 $.AUSTRALIA George Brown 212 31 11 • J Blackwood & Sons 46 0391 TASMANIA George Harvey (003) 31 6533 (002) 34 2233 VICTORIA • G.B. Telespares 328 4301 • J Blackwood & Sons 542 4321 • The Electronic Components Shop 670 6471, • Factory Controls (052) 78 8222 • Mektronics _Co 587 3888 • Truscott Electronics 723 3094 • AW.M. Electrical Wholesalers W AUSTRALIA Atkins Carlyle 481 1233 • Dobb1e Instruments 478 t 366 • George Brown 362 1044 PAPUA NEW GUINEA TE (PNG .) Pt Moresby 25 6322 Lae 42 6246 Part.2 Build your own LED Message Board Last month we introduced this exciting peripheral device for a computer which can also be driven from an IBM keyboard. This month we continue with a more detailed circuit description with emphasis on the inter£ace board. By DON McKENZIE 36 SILICON CHIP Let's pick up where we left off and continue with the description of how the display is driven. To make the text easier to follow, we have repeated the circuit of the interface board this month. The display is refreshed constantly in much the same way as a dynamic RAM. As noted before, your eyes perceive that all LEDs are switched on together but they are never all on together. Only one horizontal row is ever selected at any given time and the display data for each row is updated or "refreshed" each time a new row is selected. This refresh period is determined by the resistor and capacitor values in the 555 timer circuit on the main CPU board but more about this timer later on. The refresh time is set to just under one millisecond [lms). So allow lms for each horizontal row update. With seven rows this means a 7ms cycle to update the full display. Before updating any row, all row driver transistors Ql to Q7 on the interface board are switched off. By the way, the emit- ters of Ql to Q7 on the interface board should be connected to the + 9V rail instead of the + 5V rail as shown last month. Having turned off all the drivers, the information to be displayed in the top row [row 1) is sent out as a serial bit pattern after being assembled by the micro. This serial data stream is clocked through the daisy chained 74LS 164s on the display panels. More on the data and clock signals later. For a 16-character display, there are 96 LEDs in each row, so 96 bits must be sent through the daisy chained 164s. These chips are simple serial to parallel converters clock eight bits in and these eight bits are presented on the output pins. The last output is sent to the next 164's data input pin to form the daisy chain. When the full 96 bits of data are clocked through the daisy chained 74LS164s, they become the column [vertical) information. The full refresh cycle Assembling a mirror image of the ASCII text buffer after internal character bit pattern generation and then feeding this information to the serial to parallel converter [shift registers) ICs on the display panels, at 96 bits per row, takes a bit of CPU time. It represents around 1/3 of a millisecond for each row. At a display refresh time of lms per row this leaves us with 2/3 of a millisecond for actually displaying each row. The full sequence of events for one display cycle is as follows, with the timing shown in fractions of a millisecond: • Switch off all transistors: 0.00. • Write Row 1 data (96 bits) to display panels: 0.00 to 0.33. • Switch on Ql to display row 1: 0.33 to 1.00. • Switch off all transistors: 1.00. • Write Row 2 data (96 bits): 1.00 to 1.33. • Switch on Q2 to display row 2: 1.33 to 2.00. • Switch off all transistors: 2.00. This sequence is repeated on all rows and transistors right through to Row 7 to finish the 7ms cycle. The full sequence is continually repeated under processor driven interrupt control. Note that one LED is only on for 0.66ms in every 7ms cycle, a duty cycle of about 10%. Let's now have a look at the 74LS373 octal latch El (page 39, last month). This is the row select latch. In order to select a single row, El is loaded with the row select byte. Data bits DO, Dl and D2 are used to select rows 1 to 7 [binary 0 to 6). Data bit D3 (pin 8) is latched through -to pin 9 to enable or disable the outputs of E2, the 7445 row driver IC. When all transistors Ql to Q7 are to be switched off, D3 is high. The row information (DO to D2) is presented to the El latch together with the enable bit [D3). To latch or lock this data into El a clock pulse must be sent to pin 11 of El. This row latch dock comes from the output busy [BSY) signal of the CPU board and is inverted by gate E4b. The outputs of El not only drive E2 but also E3, a 74LS151 8-input multiplexer. If Row 1 has been set as the current row by loading El, this row select information is also presented to pins 9, 10 and 11 of E3. These signals determine which data lines DO through D7 are selected as the data input of E3. With Row 1 selected and locked into El, data bit DO is the selected data input for E3. If Row 2 was locked into El then data bit Dl would be the selected input bit for E3. The same applies right up to Row 7 and data bit D6. Data bit D7 serves another function which we will explain shortly. E3 (74LS151) simply passes the selected data bit from its input to its output at pin 5. Thus E3 performs a parallel to serial data conversion APRIL 1989 37 A000-BFFF C000-FFFF This is one of the 7 x 24 LED panels, four of which are required to make up the full display. Each panel has 168 LEDs in all. and the resulting serial data stream is fed to the daisy-chained 74LS 164 shift registers for the LED display. One half of E6, a 74LS04 hex inverter, is used to buffer the serial data to the LEDs. The other half is used to buffer the clock for the shift registers. This clock signal comes from the CPU output strobe (STB) signal. So we have one set of data (DO to D7) and two clocks, BSY and STB. That sounds confusing. The busy (BSY) clock locks the data into the row select latch, while the strobe (STB) clock is used to clock data into the 74LS164s on the display panels. Flash timer E5 is a 555 timer which provides the flashing display mode for the Message Board. The output at pin 3 is gated with data bit D7 to drive the enable pin of E3. When the timer output is low, the output of E3 is also low and so, effectively, no serial data passes through. When the timer output is high, the serial data passes through. When D7 is high, the timer has no effect and the flash mode is off. CPU board As noted last month, the CPU board is a complete microprocessor controller which uses a ZB0A microprocessor, a 2764 EPROM, a 6264 BK x 8 static RAM and an 8255 programmable peripheral interface (PPI) - see page 37, March 1989. The CPU board updates the display with CPU interrupts using an interrupt service routine, and all that is required to change the display is to load the display buffer (DISBUF) with a mirror image of the ASCII data to be displayed. The memory map is as follows: 0000-lFFF 2000-7FFF 8000-97FF BK EPROM FIRMWARE (2764) MIRROR IMAGE OF 0000-lFFF BK STATIC RAM (6264) Where to buy the parts At the time of writing no complete kits for this project are likely to be available. A complete set of printed boards plus the programmed 2764 EPROM and full instructions is available from the designer, Don McKenzie, for $150. The specially made grey Perspex channel, suitable for all LED colours, is also available from Don Mckenzie for $50 plus $15 for packing and postage. Write to Don McKenzie, 29 Ellesmere Crescent, Tullamarine, Victoria 3043. All the semiconductors and other parts are readily available from parts suppliers such as Jaycar Electronics, Altronics, Rod Irving Electronics, Geoff Wood Electronics and David Reid Electronics. 38 SILICON CHIP MIRROR IMAGE OF 8000-9FFF 74LS373 ROW SELECT LATCH (OUTPUT BUSY) INCLUDES MIRROR IMAGES. The only port addressed device is the 8255 PPL This is the interface to the computer input and message board output bus. The ZB0A's IORQ (input/output request) line is connected to the chip select of the 8255. Any time an 1/0 instruction is executed the 8255 responds. Any port from zero to 255 is the 8255's port decode. The power up routines program the 8255 to mode 1, Port A input, Port B output, and Port C handshaking for A and B. Capacitor C5 hanging on the chip select line to ground produces enough of a delay to satisfy the timing restrictions of ZB0A to 8255 interfacing. Pin 12 of the 8255 is the input BUSY to the (external) computer. This signal is inverted by E13a (74LS04) to produce the ACK signal. This means that while the 8255 is holding the ACK active (low) it sends the BUSY signal to the computer. The ACK is also connected to R4 and the data LED. The LED lights up when the BUSY is high and ACK is low, and switches off when BUSY is low and ACK is high. This LED is used for the ROM diagnostic routines to aid kit builders, and also indicates data entry into the CPU board. 2764 EPROM The 2764 EPROM has two chip enables, pins 20 and 22. Pin 20 connects to the MREQ signal of the CPU. Any memory referenced instruction will select the EPROM but no data output will take place until you also chip select pin 22. Pin 22 is connected to A15 of the CPU. Any time A15 is low and memory is selected the EPROM is enabled. This gives an effective address for the EPROM from 0000 to 7FFFH. A13 is already dedicated to the output strobe, so a maximum size of BK of EPROM can be used. 6264 static RAM The 6264 static RAM has two chip enables, pins 20 and 26. Pin 20 connects to A14 of the CPU and pin RB 2.21l 10W J3 CENTRONICS 36 PIN FEMALE INPUT GNO 16,19-30,33 J2 26 25 240 5V ------------,u+9V 9V IN 32 J1 3A 12V IN 13 GNO 25 12 BSY 0 24 BSY Ol l 1 C3 + 16~WI BC1·BC5I TANT 5x.01 COMMONo--------+---- 23~10 22~9 POWER TO PBUFF 21~8 +5V 20~7 16 19~6 IBM PC/XT KEYBOARD CONNECTIONS 5-PIN DIN SOCKET 18~5 170 02 017 100 01 016 • ,O, 02 01 0103 15~2 14~1 PINS 14,15,17,18, 31,34,35,36 N/C +5V013 I GNO 012 BSY -11 6 - 05 74LS02 4 E4b 111 - I 2 4 MMB STB J2/14 TO RN6 SIOE0-----4 OF COMPIKBO ...,_,..,.......,_. SWITCH 15 +9V Ls 120 9 14 04 -6 03 ..,.s _4 02 01 -3 8 - E1 74LS373 ENABLE OPTIONA L COM P/K 80 DECODE CIRCUIT 13 5 S1 14 I 4 2 so 15 E2 7445 3 00 -2 oL ~c JS 0825 MAL J4 OUTPUT + s v ~13,26 _ -12,25 ROW 1 12,25 7~Joi~6 +9V ROW 2 ~11,24 4701l 12 6 S2 7 -- J2/22 74LS157 KBO CLK OIN/1 17 8 -7 COM STB J3/1 J2/14 STB J2/22 07 J2/25 GND MMBCNT J2/26 +sv 18 13 STB CLOCK DATA GNO +5V 7 MMB 07 KBO DATA OIN/2 +5V 5 ACK 010 07 -9 06 1 2 KEYBOARD 4 5 COMP D7 J3/9 1 ROW 1 2 ROW 2 3 ROW 3 4 ROW 4 5 ROW 5 6 ROW 6 7 ROW 7 1k B1/E -- ROW 3 ~ 10,23 4701l al?: ROW 4 ~ 9,22 Q7 1k ROW 5 ~ ~ 8,21 ROW 6 ~ 7,20 _ _ 6,19 ROW 7 6,19 -- '-.:::,i C ~ ~o - -- ~ .,. 5,18 ~ .,. 11 10 9 07 12 06 13 D5 14 04 15 D3 1 D2 2 D1 3 DO 4 2_:r E4a 3 1 ~ 8 +5V ~ 7 LED2~ RUN R7 1501l B 1 ·:; CLOCK- - -- 4,17 ., ~ 4 -3 16 C 6 ~ 1Uw=~ -- R3 1k 2 BD646 .~l: = + - - a ' L- DATA_ -4,17 74LS04 7 ES 555 __.§ E61 1~ 5 3 12 C1 E3 74LS151 ':" 8 4 .........z R2 100k 1E,6° 14 10 7 +5V R1 100k +sv !L.-+sv BCE 7805 3,16 R4 1k ~ + 5 V ~ 2,15 ~ 1,14 -~M GND Fig.2: the interface board circuitry. It accepts data from the programmable peripheral interface and decodes it to obtain the 7 row driver lines. It also produces the serial data to drive the 8-bit shift registers in the LED display panel. 26 to A15. Pin 20 is a low select and pin 26 is a high select. This gives an effective memory map of 8000H to BFFFH. The read and write signals connected to pins 22 and 27 control the data flow to and from the static RAM. Serial Data clock The message board output strobe is produced by inverting CPU signal A13. One gate of the 741S04 (E13c) is used for this. Any time the program sets A13 high, a serial data clock pulse is delivered. During APRIL 1989 39 This is the view inside the Message Board control unit. It contains the power supply, the microprocessor controller and the interface board. power up or reset of the CPU c:11 address and data bus signals go to a high impedance state. The high to A13 appears as an output strobe every time the CPU is reset. R5, a lkO resistor, is used as a pulldown to prevent this output strobe during power up or reset. The output BUSY line is pulsed when A14 and A15 are high. This gives a starting address of COOOH. When the A15 line goes high, it disables the EPROM and a high on the line disables the static RAM. Two gates of E9 (741S00) are used to gate this signal which connects to the interface board as the row select latch clock. The 555 timer for the Z80 interrupt is set up as a 1: 100 duty cycle timer with a short low-going pulse every 0.95ms. This interrupts the CPU every 0.95ms to service the display update routine. Keyboard/computer switch As noted previously, the LED Message Board can accept input from an IBM keyboard or external computer via the Centronics port. The keyboard/computer switch S2 sets PC7 pin 10 of the 8255 either high or low to tell the CPU which input mode it is in. If it is in the corn- The front panel of the Message Board control unit carries the Reset switch, keyboard/computer switch and two LEDs (Data and Run). 40 SILICON CHIP puter mode then the data byte presented to port A is read as a full 8-bit byte and acted on accordingly as data in. If the keyboard position is selected, only data bit 7 is read in and assembled as a keystroke either 9 or 10 clocks at a time. The strobe operates in the same manner in either mode; ie, as a data bit detect. When a strobe is detected the 8255 input "buffer full" signal is set at pin 17 of the 8255. This signal passes through an inverter (E13f) to pin 17 (NMI - non-maskable interrupt) of the CPU. This interrupts the current task of the Z80A to execute a service routine for the keyboard or .computer input. PC7 can also be used to control the optional 741S 15 7 keyboard/ computer decoder shown on the circuit for the interface board. This allows you to connect up both a computer input and a keyboard at the same time. This was convenient when the software for this project was being developed but the average user probably would only need one input device connected at any given time. This decoder chip switches between the strobe and data bit 7 of both devices. CPU support Only a few CPU signals remain to be explained. The main clock for the Z80 is generated by the 4.91MHz crystal oscillator employing transistor Q1. Its ouput signal is buffered and squared by gate E13b. The Reset signal for the 8255 requires a positive-going pulse while the CPU needs a negative-going pulse as generated by the reset switch S1. The 10k0 resistor R3 is a pullup which normally holds reset pin 26 high. When S1 is pressed, pin 26 is pulled low. The 22µF capacitor across the switch eliminates any contact bounce. The reset pulse from switch S1 is also fed to gate E13d which inverts the signal and feeds it to the 8255 reset, pin 35. Next month we will conclude the Message Board description with the assembly instructions and programming via the keyboard. ~ Don't miss a single issue 1 · Electronic ! house number .j .f ! Convert a CB radio J for amateur use IF YOU'RE THE KIND OF READER that can't wait to get the next copy of SILICON CHIP, then why not have the magazine delivered direct to your door? Each month, we'll bring you the best and brightest electronics magazine in the business, put together by Australia's most experienced team. * * * * * * • l• 5-element . FM ·antenna Hili review: Yamaha's brilliant new CD player Constructional Projects for the Enthusiast Plus - the Origi nal & Best TV SeMceman, Vintag& Radio, The Way I See It, the Evolution of Electric Railways Amateur Radio The Serviceman's Log Vintage Radio The Way I See It Hifi Features & Reviews FREEPOST * SUBSCRIPTION COUPON □ □ New subscription Renewal Start in _ _ _ _ _ __ Name_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ (PLEASE PRINT) Street_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ Suburb/town _ _ _ _ _ _ _ _ _ __ _ Postcode._ _ __ 1 year ( 1 2 issues) □ $A42 Australia 2 years (24 issues) □ $A84 NZ & PNG (airmail) □ $A65 □ $A130 Overseas surface mail □ $A62 □ Overseas airmail □ $A 120 $A130 □ $A240 Enclosed is my cheque/money order for $ _ _ _ or please debit my □ Bankcard Card No. I □ Visa Card □ MasterCard I I I I I I I I I I I I I I I Subscription Hotline We can accept your subscription order by telephone. Just ring us on (02) 982 3935 and quote your Bankcard or Visa Card number and the expiry date. Detach and mail to: FREEPOST 25 SILICON CHIP PUBLICATIONS PO BOX 139 COLLAROY BEACH NSW 2097 I Signature _ _ _ _ _ _ _ _ _ Card expiry date_ _ /_ / _ _ • No postage stamp required in Australia. L---------------------- ---------------~ APRIL 1989 41 AMATEUR RADIO By GARRY CRATT, VK2YBX • The Dick Smith satellite receiver Recent developments in C band (4GHz) technology have led to the availability of affordable, low noise amplifiers suitable for the reception of satellite television signals. In fact, advances in receiver design have now been made to the point where international satellite television reception is within the reach of many enthusiasts. One company that has been involved in the development of satellite receiver design over the last few years is Dick Smith Electronics. They sell a complete 4GHz earth station for less than $7000. Lest readers are put off by such a sizeable price tag, we should mention that the major portion of the system cost is, naturally, the dish antenna which needs to be around 4 metres for reasonable results. However, amateur ingenuity being what it is, many enthusiasts are pressing surplus dishes into service at a fraction of the cost of a new unit. Of course a low noise converter can be purchased at quite reasonable cost ($699) and so can a receiver such as the one reviewed in this article. The conclusion of this preamble is that provided one is prepared to purchase a few hundred dollars worth of electronics, and to scan the surplus market for a suitable dish, good results are achievable at a fraction of the cost of a full earth station. The receiver The Dick Smith receiver tunes the frequency range from 950MHz to 1450MHz. The incoming tuned signal is mixed with the receiver's local oscillator to produce an intermediate frequency (IF) signal of 70MHz. This 70MHz IF is then converted to a baseband signal which consists of composite video and audio subcarrier signals. What makes this receiver special is the provision of user controls for both IF bandwidth (ie, at 70MHz) and audio bandwidth. This is a most necessary feature due to the variation in the signals that can be received. If the receiver was supplied with a fixed IF and audio bandwidth, optimum results could only be obtained with a signal that fell entirely within the fixed ability of the receiver. By making the IF bandwidth adjustable, the user can narrow the bandwidth to receive weak signals, and widen the bandwidth to receive strong signals. Apart from this, some satellite transponders ·operate with a bandwidth of 36MHz while others operate at 18MHz. Trying to squeeze 36MHz into an 18MHz "window" causes distortion and trying to receive an 18MHz transponder with a 36MHz receiver bandwidth allows so much noise into the system that the signal may well be unwatchable. The same applies to the audio bandwidth. Trying to receive a 200kHz wide audio signal through a 15kHz filter would render such a high level of distortion as to make the audio unbearable. Conversely, This photo shows the front panel layout of the receiver. The polarity controls are not used for Intelsat reception and could be rewired for the AFC defeat function. 42 SILICON CHIP The rear panel of the WR-3500 satellite receiver. The 70MHz "loop" connections allow the use of special interference filters if required. This is an "off air" shot of Cable Network News (CNN). This is another "off-air" shot, this time of the US NBC weather forecast. The construction is typical of most receivers, where one circuit board suits many models, hence the "missing" components. trying to receive a 15kHz audio signal through a 200kHz filter would provide little recovered audio. So we can see just what a valuable set of controls this receiver provides, by allowing the user to match the receiver parameters to the incoming signal. Another handy provision in this receiver is the accessible 70MHz "loop", allowing the insertion of filters in the IF strip, should there be unavoidable terrestrial interference. (It is a pity that the 4GHz satellite television band is also used in many areas of Australia for the distribution of data and terrestrial television signals). Apart from these features the receiver is pretty much a standard design, providing feed horn polarity and trim controls (never used for Intelsat reception), and adjustable audio tuning between 5.0MHz and 8.0MHz. Transponder tuning is made via the large control on the right hand side of the unit. On the rear of the unit are the two bandwidth controls, the 70MHz loop connections, composite video and audio outputs, a video inversion switch (originally used in the early 80s as a simple video scrambling method), an RF output for connection to a television set, and a tagstrip containing connections for polarity adjustment of the dish feedhorn. A video level control is accessible through the rear panel to allow for adjustment of the video output signal when using a monitor. The port labelled "SCPC" is not used. One feature that has not been provided is an "AFC disable" switch. This feature is useful when TI [terrestrial interference) is encountered, or when two adjacent transponders are being received. With the AFC enabled at all times, the receiver AFC tends to lock on to the strongest signal, which in some cases is a distinct disadvantage. continued next page APRIL 1989 43 The modulator used in the receiver is a PAL type. Connecting this to a PAL television set provides a black and white picture with sound. The modulator sound subcarrier is fixed at 5.5MHz as used in Australia and most other PAL countries. vcc .0047 .01 13 2.2 2.2 62k 11 15 Vi NE571 14 10 - F--OVout 10 16 Testing During testing against our benchmark receiver, we noticed that a considerable improvement in audio signal to noise ratio was achieved by using a simple NE571 audio expander. This unit is inbuilt in our reference receiver and the circuit appears in Fig, 1. It could easily be added to any satellite receiver for improved audio. Overall, the DSE WR-3500 receiver provides good performance and with a few modifica- 1-2.2'.i 12k ..,. 200pFI 200pFI .,. .,. ..,. Fig.1: this simple expandor circuit can be used to improve the audio signal to noise ratio from a satellite receiver. tions will easily perform as well as the best commercial units available overseas. It is very reasonably priced at $749.00. For further information on the WR-3500 satellite receiver, contact Dick Smith Electronics. They have a free Satellite Information Pack which is available from any of their stores. Roadrunner AR 900 handheld scanner The Roadrunner AR 900 is made by the well known Japanese communications company AOR (named after the call-sign of the company's founder, JA1AOR). It is the latest offering in small handheld scanners covering the cellular telephone band. The unit covers four frequency bands: from 60-90MHz, 11817 4MHz, 430-512MHz and 830950MHz, which should make it of particular interest to those interested in the higher bands. Five banks of 20 channels and a scan rate of 15 channels per second make for ease of operation, as the user can program a particular bank of channels for a dedicated service. For example, 20 aviation channels could be programmed into one bank while 20 marine channels could be resident in another, and the AR 900 will then scan these "service" bands extremely rapidly. Channel spacings Inbuilt and user selectable channel spacings of 5kHz, lOkHz, 25kHz and 30kHz ensure that all possibilities are covered, unlike other units on the market which do not allow correct reception of all frequencies. In fact, this is the only 44 SILICON CHIP scanner we have seen with the correct increments for the cellular telephone band. Some 25 front panel keys allow user control of all functions including scan delay, hold, skip, priority, up-down scanning, AM/FM selection, frequency search limits, search and scan. The LCD readout has a backlight switch which can be latched, a great improvement on the more commonly found "momentary on" controls. There is also a keyboard lock control to prevent inadvertent corruption of those carefully programmed frequencies by curious fiddlers. The AR 900 uses an EEPROM (electronically erasable programmable read only memory) as the permanent memory system which ensures that no reprogramming is necessary should the inbuilt 6V nicad battery run low. To ensure best possible reception under varying circumstances, the unit is supplied with two separate whip antennas. The thinner of the two gives best results on the UHF bands, while the thicker, helically wound antenna should be used for lower frequency operation. The instruction manual is generally quite good, apart from strange spelling in some places, probably resulting during the translation from Japanese to English. The audio output is a little on the low side although is quite adequate when the earphone is used. Whe·n the receiver is muted it does produce an audible hiss although this is really only noticeable when listening in a quiet room. However, This is a top view of the AR 900 scanner, showing the controls and antenna socket. _!:!undreds of other items not listed - Send 40c ·postage stamp for list 0. ~ ©[F{]&~[l&OO I ~ I [b□~□ 122 PITT ROAD, NTH CURL CURL ~ a ~ g. 0. ~ MAIL D.RDERS: BOX 156. DEE WHY. NSW 2099 1ELEPHONE (02) 905 1848 SUPER SPECIAL al ~ FM STEREO KITS -~ All three modules sup.plied are fully assembled and aligned. Circuit diagram supplied. ~ ONLY S22 g E p&p $2.00 g> Antenna $1 extra 5. ff 01------------------18 455kHz IF coils for valve radios ·. Osc coils . . Transistors $1 75c AD 161-162 AD 149 . Chrome push-on knobs . Slider Pot knobs . $3pair . $2 ea 10 for $1 . 10 for $1 ~ f ~1-------P-O_T_S-------~t t;; fg ¼ Meg Switch . . $1.00 2 Meg Ganged Tapped Log . $1.50 i~~~u:~c;~~~ntric .· S .50 ~ ... i ½ Meg Ganged log . . (/) 10~ ~ua~w~t~~c-entric Doubl~ $ ~~k 25k 4 Gang linear 20k Linear Single . 1 Meg Log Switch . . 1 Meg Dual Ganged l og . 100k Sub Mini . . 10kSubMini . 0.25 Meg Dual concentric . . 25k Dual Ganged Switch . 10k Dual Ganged Switch . 250k Dual Ganged Switch .. 1 Meg ¼ Meg Dua! Concentric Tap 40kDoublePoleSwitch ~-~ °g .! I ~ ~ ; z 1OOkDualConcentric . 2 Meg Linear Ganged . . . . $1.50 11. Meg Dual Concentric Linear $1.50 $1.50 100k log Switch . . . $1.00 $1.00 50k Mini . .4 for $1.00 0 1. 50 $2.00 S .50 . $1.00 . . $1.00 . . S .50 S .50 ;1:~~ ~~~kl~i;:~t~h . .. . 100k Log . . 50k log . . $ .50 . S .50 ~i;i:·_ 1_0~:1:~~ J ::-.: ~ §. $1.00 $1.50 $1.00 $1.00 I $1.50 5. -· I ~ : : ::~ 0.25 Meg linear or Log . . VU ~ .4 ;~~:~~'.near . . DUAL SPECIAL ~ ~~::~ ~ ~;kM~~a~i~~~ed Switch . . :1::~ 1.5 Meg Single . . . ... S .50 25k $ .50 ~ -g I Dynamic microphone Desk type METERS 1--s4_P_Ps_1_--1; $3 TEISCO Ceramic 1 E , · .... -.. ·--· ... . ········ .......... , pp $ Microphone R f--. ___-____-..-__.....__s_2 _PP_s_1_---1 o.§ 5 mixed rotary switches 1 2 mixed switches ~ .s! 1 a., :.' $2.50 $4.50 9 Touch micro switches 4 for $1 Mlcroswitches 5A 250V Mixed resistors: handy types 100 for $2 Mixed capacitors; handy types 100 for $2 §' TV stick rectifiers $1 each Transistor earpiece . 4 for $1 plug & lead g, S. l 1---------+---------1 0f - sac ~1---------+--------~~S, "'i al ~f----------+--------~~ The AOR AR 900 programmable handheld scanner has an amazing number of features in such a small package. It covers four frequency bands: 60-90MHz, 118-174MHz, 430-512MHz and 830-950MHz. any such quibbles pale into insignificance when you consider the overall level of performance and the amazing number of features engineered into such a small package. Recommended retail price of the unit is $599. For further information and the name of your nearest dealer, contact the Australian distributor, Access Communications Pty Ltd, 33 Alleyne St, Chatswood, NSW 2067. Phone (02) 406 5311. ~ ---------l a ... Slider Pots. . .. single sac; dual $1 .-~-- ~-------....... 250k dual 25k dual 1 Meg dual ~ 2 50k single 1k dual 2 Meg dual 50k single 1/, Meg dua.1 2 Meg single 0 ~ 10k single i~-VA-L-VE_S_ _ _ _5_A_ S4_ _ _ _ _ 12-A-X7- - - ~ ! :c I Are you about to change your address? Please advise us by the middle of the month to ensure that your next issue arrives at your new address. It helps us if you can send your old address label too. If you have any queries about your subscription call us or write to us at: SILICON CHIP, PO Box 139, Collaroy Beach, NSW 2097. $10 $10 $10 $7 $7 . 25 2 gang covers all Aust .,AM bands ; s4.75 ~ Notice to Subscribers 6V6 6K8 6B06 6B05 . EF86 EF86 6BM8 6BL8 6U7 6B05 6K8 6U7 . 6K7 "C I PP $1 for one or two ~ g GRAMO MOTOR & PICKUP §'. 1 $17.50 11-----------------ls. ) NEW PRICE ON i ... PP S3.50 NSW. ~ l-ln_te_rs_ta_te_S_4._4o_ _ _ _ _ _ _ _ _ _ _ _ I ;: ~ 15 ~f 0 VALVE SOCKETS OCTAL: 7 PIN , 9 PIN . 4 FOR $1 , ~ -6 Hundreds of other items not listed - Send 40c postage stamp for list Studio series 32-band 1/3-octave equaliser In this second article on our 32-band equaliser we give the construction details and a brief troubleshooting procedure. Three printed boards are used and the two main boards are linked together via removeable multiway cables. By LEO SIMPSON & JOHN CLARKE Because this equaliser is intended for use by bands and in recording applications, it is housed in a standard two-unit high 19-inch rack mounting case. It can therefore be mounted in an equipment rack, used in a free-standing mode, or stacked on top of other equipment. Ventilation is not a problem because it consumes very little power (less than 5 watts). Incidentally, a number of readers got wind of this project before the first article was published and contacted us for details. They particularly wanted to know about provision for balanced input and output with XLR sockets. We have not provided for balanced lines in this design but will do so in a later article, with a small add-on board. While rack-mounting is a feature 46 SILICON CHIP of the 32-band equaliser, the case design is somewhat simpler than many rack units. The chassis is a basic U-shape made of cadmium plated and passivated steel, while the wrapover lid is made from black Marviplate. The dimensions of the chassis, not including the front panel, are 427mm wide, 80mm high and 197mm from front to back. This gives plenty of room for all the circuitry. There is one particular point to be noted about the construction, which was touched upon in the first article. It is very easy to run into problems with earth loops when using an equaliser with other equipment which is earthed. This applies to most big power amplifiers and mixers, especially those intended for semi-professional and professional use. To avoid the earth loop problem, the equaliser circuitry is not connected to chassis or to mains earth. The chassis itself is connected to mains earth, for safety's sake. Since there is no connection between signal earths and chassis, the input and output sockets must be isolated from chassis. Nor must there be any other path from the equaliser circuitry to the chassis. This will automatically be taken care of if you follow the wiring diagrams. Slider controls If you look at the parts list for the equaliser (published last month) you will note that we have used the same type of slider for the main level control as for the 32 equaliser bands. We have done this for a number of reasons. First, and the most practical, it means that the whole design can be standardised on the one type of slider. Second, even though the slider has a special resistance taper, with an S-shaped inflection around the detent as described in the first arti- cle, it does not cause audible problems when used as a slider control the signal level increases smoothly as the slider is moved upwards, with no apparent discontinuities. The power supply PCB is mounted vertically on the rear panel to minimise residual noise. Keep all mains wiring neat and tidy and note how the earth lead is soldered to a solder lug which is bolted to chassis. Centre detent It is also possible to make good use of the centre detent available on the slider control, although the circuit needs to be changed slightly, as compared with that presented in the first article. By making this small change, it is possible to set the overall gain of the equaliser to unity, with the input level control set to the centre detent position; ie, lined up with the "flat" setting for all the other sliders. To achieve this, the lkn resistor between pins 6 and 7 of IC la should be changed to 1.5kn. This change makes the overall gain of the equaliser equal to 2.25 with the input level control at maximum setting. However, when the gain control is at the centre detent position, the overall gain of the circuit will be exactly unity because of the loading effect of the 1ookn input resistor (connected to pin 5 of ICla) on the 50kn slider pot. This is making a virtue of the centre detent. In practice, we think that most users will normally set the input level control to the centre position, for unity gain, and rarely move it from that setting. However, they then have the option of increasing the gain by up to + 7dB (2.25 times) by moving the slider to the maximum setting. The mains switch should be shrouded with heatshrink tubing after the leads have been connected to prevent accidental contact with the mains. Some users may not like the idea of using the centre detent of the input slider control in the way we have just described. They may prefer to have the unity gain setting with the slider control all the way up. In that case, Rl (the 1.2kn resistor connected to pin 6 of ICla) should be omitted. This converts ICla to a unity gain "voltage follower". Note that the component overlay diagram for the equaliser board incorporates the change mentioned above (ie, lkO changed to 1.5kO), so there is no need to worry about it just follow the diagram. Assembly procedure Most of the work in assembling the equaliser is involved with putting the three PC boards together. You can do it in any order but let's look at the slider board first. It APRIL 1989 47 0 POWER TRANSFORMER M2855 Fig.l(a): here's how to mount the parts on the power supply PCB. You can use PC stakes to terminate the + 15V, - 15V, GND and LED connections but be sure to . solder the mains leads and transformer leads directly to the board. The completed power supply should be checked out as detailed in the text before connecting it to the remaining circuitry. IC2-IC! *OMIT FOR UNITY GAIN POTENTIOMETER BOARD • • • • • • • • • nnnnnn· • 1• • • • • • • • S b • • 16Hz • •• • 20Hz • • • 25Hz 32Hz • • 40Hz • • 50Hz • • 63Hz • • 80Hz • • 100Hz • • 125Hz • • 160Hz • • 200Hz • • 250Hz 1••··· •• • SK2b • • 320Hz • • 400Hz • 1• • • • SKJb • 500Hz • • 630Hz • SILICON CHIP • 800Hz Fig.l(c): this board accommodates all the slider controls. Make sure that each slider control is square onto the board and parallel with its neighbour before soldering its leads. The five multipin headers are mounted on the copper side of the PCB, along with 6 PC stakes which terminate the shielded cable connections. 48 • • • 1kHz I : LF347 ONLY Fig.l(b): this is the parts layout for the main equaliser PCB. Push all the parts down onto the PCB as far as they will go before soldering the leads and take care to ensure that the ICs are all correctly oriented. Connections to the slider board are made via multi-way plugs and sockets. • nn· • • • • • • • 1• • • • • • • • SK4b • • • • 1.25kHz 1.6kHz • • 2kHz • • 2.5kHz • 3.2kHz • • 4kHz • • 5kHz • • 6.3kHz • • 8kHz • • • • • • 10kHz 12.5kHz 16kHz • • 20kHz measures 373 x 75mm and is coded SC 01103893. This board accommodates only the slider controls and does riot have any other components. It connects to the main equaliser board via five multiway cables which are terminated at either end by sockets. Fig.1 shows how the parts are mounted on the board. It is simply a matter of inserting each slider and soldering its three pins to the board pattern. Make sure that each slider is square onto the board and as you solder each one in place, make sure it is parallel with its neighbour. When all 33 sliders are soldered in place, five multipin headers need to be soldered to the board to take the interconnecting cables. The 8-way type we used are stocked by Jaycar (Cat. HM-3210). You will need one 4-way and four 8-way headers. The latter can be obtained by cutting an 8-way type in half. Don't throw the unused half away - you'll need it for the main equaliser board. The multipin headers are soldered to the copper side of the slider board, using the short pin side. The long pins take the matching socket plug. With the headers in place, the slider board is complete and can be set aside until you are ready to install it in the, case. Main equaliser board The main board accommodates all the equaliser circuitry except for the power supply. It measures 280 x 146mm and is coded SC 01103891. It has eight LF347 quad op amp ICs and one LM833 dual low noise op amp IC. As mentioned in the first article, you must not substitute the ostensibly equivalent TL074 for the LF347 as the TL074 is liable to go into oscillation momentarily after the power is switched off, giving rise to an audible "chirp". We suggest that you install all the wire links and resistors first. Note that a lot of the resistors are 1 % tolerance types having five colour bands. It is quite easy to confuse the values of 5-band resistors if you are not used to them so it is a good idea to check each value with a digital multimeter (switched to "Ohms") before it is installed. APRIL 1989 49 The connecting cables between the main board and the potentiometer board are run via multipin headers and matching plugs. Forget the insulated wire links on the back of the potentiometer board - we goofed on the prototype. The PCB pattern has been corrected. To make it easier, we have tabulated the specified 1 % values below. Note that the tolerance band is brown. 1Mn - brown, black, black, yellow, brown. 220kQ - red, red, black, orange, brown. lOOkn - brown, black, black, orange, brown. 10kn - brown, black, black, red, brown. 1.5kQ - brown, green, black, brown, brown. 1.2kQ - brown, red, black, brown, brown. 1. lkQ - brown, brown, black, brown, brown. lkn - brown, black, black, brown, brown. 9100 - white, brown; black, black, brown. Even though we have given the colour codes, you should still use your multimeter to check the values, to be certain. Next, install the op amps. Note that the middle row of op amps is oriented differently from the outer two rows and that the LM833 (ICl) is oriented differently to IC6 and IC7, in the same row. Check the 50 SILICON CHIP component overlay diagram before you insert each IC and double check it before you solder it in place. Incidentally, we don't recommend IC sockets for this project. You can now install the multipin headers and then the capacitors. Make sure that all electrolytic capacitors are inserted with the correct polarity. Lastly, insert the 7 PC pins for connections to the power supply and input and output shielded cables. Carefully inspect your work and then put the board aside. Power supply board This board accommodates all power supply components, including the power transformer, but not some of the bypass capacitors which are on the main board. The supply board is coded SC 01103892 and measures 112 x 74mm. Assembling this board is easy but correct polarity must be observed for all the components: diodes, electrolytic capacitors and the 3-terminal regulators. Note that both regulators face the same way but make sure you don't inadvertently swap them over. The transformer is also mounted on this board, using screws, nuts and lockwashers. Terminate the primary and secondary wires and then put the board aside for the moment. Chassis assembly We will assume you have complete metalwork for this project and so work on the chassis is basically a matter of installing the completed printed circuit boards and running the connecting ea bles between them. The screen printed front panel should not be permanently fitted until all the circuitry has been powered up and checked for correct operation. If you do put the front panel on before all the checking has been done, you are sure to have to do some troubleshooting and this increases the chances of marking or damaging the finish. The slider board is the first to be installed. It is mounted using ten 25mm-long x 3mm countersunk screws fed through 18mm-long MAIN BOARD POTENTIOMETER BOARD SK3•D 0 TPUT~ oo=~ ""~ "'4 m~\, '\2 · ·~ ~ + ,, . SK3bo ""~ ,~~ >O ., z > ., I + ~ ~ POWER SUPPLY BOARD TO TRANSFORMER ). PRIMARY~ r-r- -~~\: \ \ 8 7 6 N (BLU) S A (BRN) / CORO CLAMP GROMMET (~ ~~(GRN/YEL) ~ ~ EARTH LUG Fig.2: this chassis wiring diagram shows how all the cables are installed. Connect SKla on the main board to SKlb on the potentiometer board, SK2a to SK2b and so on. Watch out when hooking up the + 15V, GND and - 15V connections between the power supply PCB an the main PCB - the order on the two boards is different. APRIL 1989 51 -- ~ ~ Use cable ties to separately bind the shielded audio cables and the power supply wiring to keep everything neat and tidy. Note that the two RCA sockets on the rear panel must be insulated from chassis to prevent earth loops. to hollow spacers and secured with nuts. The 18mm spacers give the correct spacing for the slider bodies from the rear of the front panel and ensure that the slider levers protrude by the right amount. 52 SILICON CHIP cTT Incidentally, although we have not mentioned it previously, these sliders are not fitted with separate knobs - their plastic actuators are used as is. If knobs were used, the spacing between sliders would have to be increased and the whole project may not have fitted inside the specified rack case. With the slider board fitted into place, install the bypass switch. This is a DPDT push on/push off switch with integral mounting bracket. It is mounted using two tt::::::::::.--i rf~\ 0 .ii: The potentiometer board is mounted behind the front panel on 10 18mm-long hollow spacers and secured with screws and nuts. If you can't get 18mm spacers, use 15mm spacers instead. 12mm-long threaded pillars. Secure the two pillars to the bracket using 6mm-long x 3mm roundhead screws. This done, mount the bracket and pillar assembly inside the chassis using countersunk 3mm screws, also 6mm long. Countersunk screws are necessary here, so that the front panel can mount flush against the front of the chassis. Once you have the slider board and the bypass switch fitted , you might like to check the fit of the front panel on the chassis. Fit it temporarily and check that all the sliders operate without fouling. Any necessary adjustments should be done now before assembly proceeds further. Fitting the power supply The power supply can now be fitted. First fit the power cord, using a cordgrip grommet to secure the cord at the rear of the chassis. The earth wire is terminated at the rear of the chassis using a solder lug secured with a screw, nut and lockwasher. The active and neutral wires are terminated to the power supply board and then four insulated wires are run to the DPDT toggle switch at the front panel. These wires should have 250V AC-rated insula- tion and then preferably be sleeved to hold them neatly together. When the wires are soldered to the switch, a length of heatshrink tubing should be fitted right over the switch to completely shroud it and thereby prevent accidental contact with the 240V AC mains. You can fit the power switch temporarily at the front of the chassis so that testing can proceed. Do the same with the LED bezel. Mount the board vertically at the rear of the chassis using four pillars, with screws, nuts and lockwashers. Incidentally, while there is plenty of space to mount the power supply on the bottom of the chassis, we mounted it vertically because that position gave the minimum residual noise. Now apply power and measure the voltages at the supply outputs. They should be close to ± 15V DC. More particularly, the positive rail should be within the range from + 14.4V to + 15.6V. Similarly, the negative rail should be within - 14.4V to - 15.6V although generally they will be fairly close to 15V. On our prototype, the + 15V rail was + 14.78V while the - 15V rail was - 15.24V. If the supply rails are not correct, disconnect the power and 0 I· 0 ~ - 0 Fig.4: half-size reproduction of the potentiometer PCB. The full size pattern measures 373 x 75mm. check out the board for faults. Check also that the LED is working. Now the main board can be checked. You can do this before it is installed; that way, you don't have the hassle of removing the board to APRIL 1989 53 This vi~w shows the completed equaliser before the installation of the front panel. Note that all the slider potentiometers must be lined up accurately, so that their actuators pass through the front panel slots. do any repairs, should they be necessary. Sit the board on an insulating surface and connect the three supply wires from the power supply board. Do not connect the five multiway cables for the slider board. Now apply power and check that + 15V is present at pin 8 of ICl and at pin 4 of each LF347'quad op amp. Similarly, check that the - 15V rail is present at pin 4 of ICl and pin 11 of each LF347. Next, check the offset voltage of every op amp on the board. That means checking pins 1 and 7 of the LM833 (ICl ) and pins 1, 7, 8 and 14 of the LF347s. The voltage in each case should be within a few millivolts of OV. If one of the op amp outputs is not at OV it is likely to be at either + 15V or - 15V due to an open circuit connection on the board. If you get this sort of fault , check your soldering carefully. If all the voltage checks go as they should, you can then install the main board in the chassis. It is mounted using five pillars with screws and nuts. Alternatively, you could use plastic PC mounts. Next, there is the task of making five multiway cables with header plugs (Jaycar Cat. HM-3220). Ea ch lo 0 N C') C0 (') 0 .,.... .,.... 0 (.) (,/) 0 of I I I I ~ Fig.5: full-size reproduction for the power supply PCB. Full size positive film transparencies for all PCBs are available for $20 (see panel). 54 SILICON CH IP connector pin is soldered individually to the rainbow cable and then inserted into the plug. To complete the equaliser, you need to install the two insulated chassis-mount RCA sockets and run the shielded cables. Fig.2 shows how to do this. Testing When everything is complete, you can connect the equaliser to a mixer or control unit with headphone outputs. With no signal source connected, power up the equaliser and listen to the noise output via the mixer and headphones. Noise levels should be very low and any buzz or hum should be practically non-existent. Finally, check that the noise level increases as you push sliders up and that the noise reduces when sliders are pushed down. If all that checks out, your equaliser is ready forwo~. ~ Where to buy the kit Complete kits for this project will be made available by Jaycar Pty Ltd for $229.00. Note that two of the PC patterns are too large to be published full size in the magazine . For those who wish to make their own PC boards , we can supply a set of full-size positive film transparencies for $20.00 . Alter· natively, for those people who have access to enlarging photo· copiers, we have published the two larger boards half-size . WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS .. WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR C GET YOUR GOODIES FROM WOODIES! ~ ~ Cl: C) IJ.. Cl C) ~ National Semiconductor Linear Data Book Bargain! Limited supplies of the lour volume set of linear data books now available. Over 4kg of data sheets and application notes from the linear leaders, and now we have had them printed in Australia. Sorry we can't split the set, although we have a few copies of Volume 1 at $22.00. Each set contains:- ~ i5 Cl: C) IJ.. Cl C) ~ ~ :i:(._J Cl: C) IJ.. Cl C) ~ Linear Vol 1 - 1988 Ed ition Voltage Regulators Op Amps Bullers Volt Comparators lnstrumentat'n Amps Surface Mount Volume 2 - 1988 Edition Active Filters Analog Switches A to D Converters D to A Converters Sample & Hold Temp Sensors Voltage References Vo lume 3 - 1988 Edition Audio Circuits Radio Circuits Video Circuits Motion Control Special Functions Applications - 1986 Edition Over 150 notes and tutorials covering thousands of applications Set of 4 fabulous books only $59.50 Plus Delivery - NSW $ 5.00 Vic,Old,SA $ 7.00 WA,Tas,NT $12 .00 Kynar Wire-Wrap Wire ~ :i: (._J Cl: C) IJ.. Cl C) ~ At long last we have located wire wrap wire at a sensible price. A good range of colours is available and conductor is 30 gauge silver plated copper. Printer Cables Data Switches We now have two new data switches in our range, suitable for switching one printer Monitor Extension Cable Now you can get that extra desk space you need. With one of our 9 way extension cables it's easy to mount your monitor out of the way. DB9 Plug to DB9 Socket Length 1.5 Metres$ 19.95 Popular MAX232 This CMOS RS232 dual receiver/driver has taken the "'""'I ll~UU - - t --<><: h--l---< rnit•os '"" "" I :tJll•l'IJT between two compu!ers or one computer between two printers . Total flexibility at a low cost. Serial (RS232) Switch$ 45.00 or Parallel Centronics $ 55.00 You will probably need some of our ever popular printer cables with your new data switch , so here's what we have:0825 to Centronics 2 Metres $ 14.95 4 Metres $ 29.95 Centronics to Cenrronics Length 2 Metres $ 29.95 Chips off the Old Block From the National Semiconductor linear range we have selected some of their more popular recent offerings. LM607CN Precision Amplifier Trimmed for low offset voltage to ensure guaranteed drift specs as low as 0.3µV/°C with offset as low as 25µV. Open loop gain ol 5million . CMRR of 140dB typ. Input bias 1nA typ $ 2.65 LM837N Quad version of popular LM833 low noise amp for professional audio $ 3.60 LM1875T 20W audio amplifier in a TO-220 package. 0.05% distortion at 1kHz,20W. Bandwidth to 70kHz . 3A current capability. Short circuit protection. 94dB ripple rejection $ 5.70 LM6365N Very high speed (like 300V/µS!) op amp. Gain Bandwidth product of 725MHz! Only 5mA supply current. AV>25 . Uses National' s VIP technology $ 4.70 LMC555CN CMOS 555 timer (need we say more?). Not at this price! $ 1.20 LMC567CN CMOS version LM567CN ton e decoder with 20:1 frequency range. Logic compatible - will sink 1OOmA. Ideal for preci sion oscillators , frequency control . Centre frequency adjusts from 0.01 Hz to SO0kHz $ 2.40 LMC660CN CMOS quad operational amplifier. 126dB max gain. 0.01 % di stortion at 1Ok Hz. 40IA bias current. Rail to rail output swing $ 3.60 LMC7660IN h-+----< " ] source for ICL7660 Black Blue Brown Green Grey Red Orange Violet White Yellow Per Roll $ 9.50 Cut and Stripped Packs of 100 Length is overall and includes 1• exposed wire lead for wrapping . Black Blue Green Red White Yellow $ 3.60 EXAR Products country by storm . No wonder when it produces the ±10V supplies from 5V power. Wide ly used in serial transmission applications we have good stocks to help you with your project.Still only $ 7.95 100 ft Rolls Second XR-558 Quad tim er $ 3.30 XR-2206 Fune gen $ 8.90 XR-2209 Preci sion oscillator $ 5.20 XR-8038A Waveform generator $ 7.30 4 inch Per Bag $ 4.80 5 inch Per Bag $ 5.60 6 inch Per Bag. $ 6.25 Rolls from 50 ft to 1000 ft and ,.,~ cut lengths from 2.5 inch to 10.0 inch in bags of 100 and 500 are available to special order. And if you're quick we've the genuine OK Battery Powered Wire Wrap Gun Features positive indexing and anti-overwrapping , - Suits 26, 28 and 30AWG depending on bits (extra). Runs on ·c· si ze cell s. Limited Quantity BW-2630 $ 99.50 GEOFF WOOD ELECTRONICS PTY LTD 229 Burns Bay Road, (Corner Beatrice St.) INC IN N s w Lane Cove West, N.S.W. P 0. Box 671, Lane Cove N.S.W. 2066 Telephone: (02) 427 1676, Fax: (02) 428 5198. 8.30am to 5.00pm Monday to Friday, 8.30am to 12 noon Saturday. Mail Orders add S5.00 to cover postal charges. Next day delivery in Sydney add $5.00. All prices INCLUDE sales tax. Tax exemption certificates accepted if line value exceeds $10.00. BANKCARD, MAS TE RCA RD, VISA, CHEQUES OR CASH CHEERFULLY ACCEPTED New 80 series multimeters from Fluke For quite a few years now Fluke has been the leading name in multimeters and their 70 Series have probably been the most copied. Now Fluke has produced the 80 series which incorporates many new measurement features including frequency, duty cycle and capacitance. By LEO SIMPSON When you think about it, there are a number of points about present day digital multimeters that are not ideal. This is probably another way of saying that everyone has a "wish list" when it comes to defining the "perfect" multimeter . 56 SILICON CHIP Let's note some of our wishes which have come to mind when we have been working at the bench. Number one is the point that the digital display does not respond fast enough when first measuring a voltage. The meter could be badly overloaded but you have no indica- tion until the meter finally produces a readout. Second, a digital display is useless when you are measuring voltages which are fluctuating. There is nothing more frustrating than trying to make a measurement in these circumstances. When they occur, the only thing to do is to stow the digital meter and get out the trusty analog meter - it may not be as sensitive but it will give you a fair idea of the voltage. Third, many multimeters are hopeless when measuring resistance. The readout bounces all over the place and does so even when you short the leads together to check that your lead connections are OK. This is the top view of the double-sided printed board for the new 80 series Fluke multimeters. Note the surface mount processor and the extensive use of the very tiny surface mount components. Fourth, when measuring AC signals most digital multimeters are woefully inadequate when the frequency starts to rise. Most cannot measure signals much above lkHz. Fifth is battery life. Whether the meters are just hungry on batteries or whether it is chronic forgetfulness on the part of the users in not turning them off, some multimeters do go through more than their share of batteries. Sixth is fragility. Too many multimeters are just too fragile and are liable to give up the ghost if you drop them or, for example, inadvertently try to measure Volts when on Ohms. Notice that we haven't mentioned any fancy features on this list so far. If we could get a multimeter which addressed all the above problems and then added new features on top, that would be really something. The new Fluke 80 Series Fluke started with a fresh page when they produced the 80 series. They incorporated many of the features of the highly successful 70 series and the ruggedised 20 series. In appearance, the 80 series bear a family resemblance to the 70 series but they are larger, heavier, have a bigger digital readout and have 7 or 8 pushbuttons which provide extra measurement features. Heart of the new multimeters is a new single chip IC designed and manufactured in-house by Fluke. This custom chip combines a programmable 13-bit analog-to-digital converter, a microprocessor, 4K of RAM (random access memory), a 128 segment LCD (liquid crystal display) driver, a frequency counter, eight amplifiers and 60 analog switches. As well as going to a custom chip, this is the first Fluke handheld multimeter to make extensive use of surface mount components on a tightly packed double-sided PC board which has very fine tracks indeed. The custom chip itself is housed in a 100-pin surface mount package and the whole multimeter is put together on a robot assembly line. It certainly is a far cry from the digital multimeters of only a few years ago. Features All three meters in the Fluke 80 series - the 83, 85 and 87 - are very similar in appearance and measurement features. Their overall dimensions are 186 x 86 x 34mm and mass is 360 grams. All have a large rotary switch to select the following measurement modes: AC Volts, DC Volts, DC Millivolts, Ohms, Diode Test, AC Amps (or milliamps) and DC Microamps (AC or DC). In all the above modes except Diode Test, the meters are autoranging with the digital display being updated four times a second which is fairly fast as most meters go. In the Diode Test mode the open circuit voltage from the prods is 3 volts DC and the maximum current is lmA. This is enough to test all diodes and will illuminate LEDs too - a handy feature. In the AC Volts mode, there are five ranges, 400mV, 4V, 40V, 400V and 1000V; in DC Volts mode, four ranges, 4V, 40V, 400V and 1000V, with 400mV available in the DC mV mode. In the Ohms mode, there are six ranges: 4000, 4k0, 40k0, 400k0, 4MO and 40MO. For current measurements, the ranges are 40mA and 400mA when using the "mA" input terminal and 4000mA and 10A when using the "A" input terminal. In the AC mode, the frequency response is greatly improved. For the models 83 and 85 it is specified up to 5kHz, while for the 87 model, APRIL 1989 57 Relative and Touch Hold modes Each Fluke 80 series multimeter comes with a protective yellow rubber holster which incorporates a flexible prop. This can be bent as you want it to use the meter in almost any position. the frequency response is specified up to 20kHz. In fact, we found the frequency response of the 80 series to be far above the figures just quoted. For the claimed accuracy, the 85 was good to beyond 35kHz while the 87 was good to beyond 65kHz. And if you wanted to talk in practical dB limits (say ± 3dB), the 87 is usable beyond 200kHz. In fact it appears to have a rising response above about lO0kHz. 4000 count Note that all the ranges listed above have a maximum count of 4000 instead of the 2000 count of normal 3 ½-digit multimeters (or the 3200 count of the Fluke 70 and 20 series meters). Depending on the range of measurements you make in the normal course of work, the 4000 count can be a lot more convenient than that from a standard 2000 count meter. It increases the resolution and frequently avoids the need to overrange. For example, you can measure a voltage of 3 volts with 4-digit resolution on the Fluke 80 series (eg, 3.056V) compared with only 3-digit resolution on other multimeters (eg, 3.05V). Capacitance and frequency When in Ohms mode, pressing the blue pushbutton brings up the 58 SILICON CHIP capacitance mode. You can measure from 5µF to about l00pF directly. When in any of the voltage or current modes, pressing the "Hz" pushbutton brings up the frequency counter mode. Pushing the "Hz" button again measures the duty cycle of the signal frequency and pushing the button again puts you back in the original measurement mode. You can measure up to 200kHz with up to 5-digit resolution. Pushing the Min Max button while in any of the voltage, current or resistance modes will record the minimum, maximum and average values for a period up to 36 hours. Each time the meter measures a new maximum or minimum it will give an audible beep. At any time you can read off the stored minimum, maximum and average values by just pushing the Beeper button to take each value. This mode can be very handy if you are monitoring a circuit for fault conditions. It can catch glitches as short as one millisecond although the nominal response time is lO0ms. For higher accuracy, to record slow drifts in voltage, a one second response time is available. Holding down the Min Max button for two seconds stops the recording mode and restores normal operation. Relative mode is handy when you want to record the change in a measurement from some reference value. This could, for example, be when you are measuring the frequency response of an amplifier. You just measure the desired reference voltage (or voltage or resistance) and then press the Rel button. This zeros the reading and all future readings are then positive or negative with respect to the initial reference. Touch Hold mode is very handy when you are measuring in a tricky situation; for example, when you can't look at the meter while you place the probes on the circuit. You just select the measurement mode, push the Hold button and place the meter prods on the circuit. The meter then beeps as soon as the measurement has stabilised (it autoranges as necessary) and the reading is then held on the digital display. Manual range change All the modes listed above have autoranging as a standard feature but there are times when you want to select and stay on a particular range. This is done by pushing the Range button. You can select a particular range (voltage, current, resistance, capacitance) by pushing the Range button a number of times. And if you want to go back to autoranging you press the Range button for two seconds. Bargraph and pointers While these new Fluke multimeters are ahead of others in having a 4000 count display which updates 4 times a second, the digital display is not fast enough to follow rapidly rising or fluctuating readings. Fluke addressed this problem in their 70 series when they introduced the concept of an analog bargraph display. While this was a step in the right direction, it did not fully replace the need for an analog meter with a "real pointer". In the new 80 series, Fluke have refined the bargraph concept. It now has 40 segments (versus 31 in D S EMI C ONDUCTORS ! ALWAYS CHECK OUR PkiCES BEFORE YOU BUY! 1-9 10+ DIECAST BOXES Diecast boxes are excellent for RF shielding , and strength. Screws are provided with each box. H11451100x50 x25 mm, .. $ 5.95 H11452110 x 60 x 30mm ... $ 6.50 H11453120 x 65 x 40mm ... $ 6.95 H11461120 x94x53mm ... $11.50 H11462188 x 120x 78mm .. $13.50 H11464188 x 188 x64mm .. $29.50 SURGE BUSTER! 6 PROTECTED POWER OUTLETS Protect your val uable electronic equipment from damaging power surges. Ideal for protecting personal computers, video equipment, colour TVs, amplifiers, tuners, graphic equalisers, CD players etc. 4164-12 ........... $5.40 41256-12 ····· ····$18.50 2764 ................. $5.95 27256 ...... ......... $10.95 27512 ............... $23.95 62256 ............... $35.00 NEWLM12CLK -====-=========- QUALITY LEDS Cat. No. Description Price Z101403mmRed ....... $0.15 Z10141 3mm Green $0.20 Z101433mmYellow ..... $0.20 Z101453mmOrange ..... $0.20 Z101505mmRed .......... $0.10 Z101515mmGreen $0.15 Z10152 5mm Orange ..... $0.15 SPECIFICATIONS: Electrical rating : 240V AC, 50Hz, 10A Complies with Australian Standards. Approval number N10084. 3 x Metal Oxide Varistors (MOV) Surge/Spike Rating (each MOV):. 4,500 amps (Bx 20us) Energy Absorb. Factor each MOV: 75 joules (10 x 1000us) Maximum Clamping Voltage: each MOV: 71 O volts at 50 amps Response time : Less than 25 Nanoseconds. X10086 .. ... ......... $69.95 150W OP AMP ..... ..... ..... $39.95 CANNON TYPE CONNECTORS AT SPECIAL PRICES!! Cat. No. Description Price We have a great range of panel meters at great prices! Cat.No. Description Price 010500 010502 010504 010510 010518 010520 010525 010530 010533 010535 010538 010540 010550 010560 MU45 0-1mA MU45 0-50uA MU45 0·100uA MU45 0·5A MU45 0·1A MU45 0-1A MU45 0·20V MU52E 0·1A MU52E 0-5A MU45 VU PMetre MU65 0-50uA MU65 0-lmA MU65 0-100uA MU65 0-20V 12.50 12.50 12.50 12.50 12.50 12.50 12.50 14.50 14.50 14.95 16.95 16.95 16.95 16.95 Low dual cone, wide range . 200mm (Sin.). Ideal for public =~drf~;,;,~~~~g~i~~?u:~~i~ese prices! ............... Cat.C12000 1-9 10+ Was $3.00 ... ...... NOW $2.40 P10964 3 pin line female $5.95 throw away batteries with these quality Nlcads and Rechargers! Size Desc. 1-9 10 + 100+ AA 450 mA.H . $2.95 $2.75 $2.50 C 1.2 A.H. $9.95 $9.50 $8.95 D 1.2 A.H. $9.95 $9.50 $8.95 • • • • Light weight Sturdy construction Easy to remove tip Excellent value for money! Cat. T11281 .... ... $13.95 UV EPROM ERASER PORTABLE 16 DRAWER CABINET • Overall size: 270(L) x 160(W) x 165(K)mm • Drawer size : 142(L) x 56(W) x 31 (H)mm • Metal case, clear plastic drawers • Carry strap • Stackable or wall mountable 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 for less chips) . Features include: • Chip drawer has conductive foam pad • Mains powered • High UV intensity at chip surface ensures EPROMs are thoroughly erased • Engineered to prevent UV exposure • Dimensions 217 x 80 x 68mm WITHOUT TIMER · Cat. X14950 ......... Normally $97 Special, $79 Special , $99 • ½" high contrast LCD . • Automatic over-range indication with the "1" displayed. • Automatic polarity indication on DC ranges . • Diode testing with 1 mA fixed current. ................... . .... . :r:1.e-·.-- ... . . . . . RODIRVING ELECTRONICS ~ WITH BUILT-IN TIMER Compact, rugged, battery operated, hand held 3 1h digit multimeter. - (10MHz) $5 .50 Cat. X14955 ....... Normally $139 Features ... 8087 CHIPS GENUINE INTEL CHIPS! 8087-3 (4.77MHz) ......... ............ $245 88008877-21 (8MHz) ...... . ...... ········· $$437505 80287-6 (6MHz) ....... ........ ........ $375 80287-8 (8MHz) ...... .. ....... ... .... $555 80287-10 (10MHz) .................... $690 Was$4.50 .. .. ..... Now $3, 25 =:= . ~ 8 0 3 8 7 - 1 6 (16MHz) .................... $995 P10966 3 pin chasis female li!I..__ . . 80387-20 (20MHzl ....... .. ........ $1460 w $4 95 NOW $3 45G!"ail:lill:•II 80387-25 (25MHz) .. ..... ... ...... $1860 as · ···· ·· ··· • ECONOMY ANTISTATIC SOLDER SUCKER •' Save a fortune on expensive PANEL METERS GALORE! SP02 5 6 SPEECH CHIP $21.95 ::9:::in line mNOW $2.90 P1 0962 3 pin chasis male H10085 ... ..... ..... . METEX3800 MULTIMETER $5.00 $17.50 $5.50 $10.50 $22.95 $32.00 All sales tax exempt orders and wholesale Inquiries to: RITRONICS WHOLESALE, 56 Renver Road, Clayton. Phone : (03) 543 2166 (3 lines) Fax : (03) 543 2648 SYDNEY: 74 Parramatta Rd . Stanmore. 2048. Phone (02) 519 3134 Fax (02) 519 3868 MELBOURNE: 48 A'Beckett St. Phone (03) 663 6151 NORTHCOTE : 425 High St . Phone (03) 489 8866 CLAYTON: 56 Renver Rd . Phone (03) 543 7877 MAIL ORDER& CORRESPONDENCE: P.O. Box 620, CLAYTON 3168 Order Hotline : 008 33 5757 (Toll free. strictly orders only) Inquiries : (03) 543 7877 Telex : AA 151938 Fax : (03) 543 2648 METEX3530 MULTIMETER ORDER HOTLINE Compact. ru~ged, battery operated, hand held 3 /2 digit multimeter. fTOLLFREEJ 008335757 Features ... STRICTLY ORDERS ONLY • ½" high contrast LCD. • Automatic over-range indication with the " 1" displayed. • Automatic polarity indication on DC ranges . • Capacitance measurements to 20uF • Diode testing with 1 mA fixed current. METEX M-3650 MULTIMETER 20A, 31,'.z digit frequency counter multimeter with capacitance meter and transistor tester. Features include a frequency counter (to 200kHz). diode and transistor test, continuity (with buzzer), capacitance meter, up to 20 amp current measurement. LOCAL ORDERS & INQUIRIES (03) 543 7877 METEX4500H MULTIMETER 10A, 41;., digit multimeter with digital hold, transistor tester and audible continuity tester. CHECK THESE FEATURES ... • Audible Continuity Test. • Transistor hFE Test. • Audible Continuity Test. • Transistor hFE Test. SPECIFICATIONS Maximum Display: 1999 counts SPECIFICATIONS Maxfmum Display: 1999 counts 3½ digit type with automatic polarity indication. Indication Method: LCD display. Measuring Method: Dual-slope in A-D converter system. Over-range Indication: "1" Figure only in the display. Temperature Ranges: Operating 0-C to + 40,C Power Supply: one 9 volt battery (006P or FC-1 type of equivalent) Cat.O91530 ....... Normally $109 3 ½ digit type with automatic polarity indication . lndfcatlon Method: LCD display. Measuring Method: Dual-slope in A-D converter system . Over-range Indication: "1" Figure only in the display. Temperature Ranges: Operating 0-C to + 40•C Power Supply: one 9 volt battery (006P or FC-1 type of equivalent) Cat. 091540 ...... Normally $139 • Audible continuity test • Transistor test • Diode test • Quality probes • ½" High contrast LCD. • Full overload protection •20 Amp • Built in tilting bail • Capacitance meter • Instruction manual 091550 .... .. ........ . Normally$165 • Readout hold • Transistor Tester • 4½ digit x ½"(H) LCD • Audible continuity tester • Quality set of probes • DiQital readout hold • Built in tilting bail • Instruction manual • hFEtest • Diode Tester • Vinyl case 091560 ........ ....... Normally $175 SPECIAL$79 SPECIAL $109 Special , only $129 Special , o n ly $1 59 CHECK THESE FEATURES .... POSTAGE RATES: $1 - $9.99 .. $10 - $24.99 .... ............... $25 - $49.99 ........... $50 - $99.99 . ... S100 plus ...... $2.00 $3.00 $4.00 $5.00 $7.50 The above postage rates are for basic postage only. Road Freight, bulky and fragile items will be charged at different rates. Errors and omissions excepted. Prices and specifications subject to change. IBM' , PC' . XT", AT' . are registered traclemar1tsol International Business Machines. •Apple Is a registered tradernar1t. 'Denotes registered tradmar1ts ol their respective owners. [ffil VISA Yes we pulled a Fluke 85 completely apart and then put it hack together again, after which it worked as normal. The rotary switch does not select ranges; the processor does that as part of normal autoranging. the 70 series) and a calibrated scale to match the 4000 count display. And it updates 40 times a second which is more rapid than the eye can follow or any analog meter can match, for that matter. So at last we have a digital multimeter which can truly follow rapidly varying measurements. On the Fluke 83 and 85 models, the analog display is in the form of a bargraph while on the top rrrodel, the 87, the analog display is in the form of a short pointer (ie, only one segment is energised at a time). There is quite a bit more to the bargraph/pointer display than we have space for apart from mentioning that the display has a useful nulling mode when the Rel button is pushed and it "wraps around" four times on each range. Overload, bash and splash protection Whether you've noted it or not, the list of features so far goes some way towards meeting the "wish list" at the start of this article. We have covered the points about 60 SILICON CHIP display updating, analog response and AC frequency response. Where the Fluke 80 series multimeters really excel is in their ability to take abuse . In fact, demonstrating their ruggedness is enough to make any careful user wince. For a start the case is splash proof and dust proof so that dirt, grime and spilt drink will not trouble it. The Fluke 70 series are pretty rugged too and able to withstand the odd fall from the workbench but the 80 series is even better protected with its bright yellow rubber holster. This not only gives the meter better protection against bashes but gives it more "heft" and adhesion to bench surfaces so that it is unlikely to be dragged off the workbench by a tangle of test leads. And if you are one of those people who hooks the meter up to high voltage without checking the measurement mode beforehand, the 80 series have an answer to that too. For example, if the meter is switched to the AC Voltage mode and you plug the prods into the Amps terminal, it will beep at you. If you switch to the resistance, capacitance or diode test function and plug one of the prods into the Amps terminal, it will beep more frantically. This is the first line of defence. For the second line of defence, the 80 series have 1 amp and 15 amp 600V cartridge fuses and 1000 volt RMS protection for the resistance and diode test modes. Other features Two more features stand out and they both apply to the 87 model. These are the 4 ½ -digit display mode and true RMS indication. While all three modems use essentially the same 4 ½ -digit liquid crystal display, only the 87 model has it as an operational feature for volts and current modes. It is available in all three models for frequency measurement. You can engage it for volts, current and resistance measurement modes in the 8 7 by pushing the yellow button as you turn the meter. While all Fluke multimeters come standard with a protective yellow holster, it -is available in a metallic grey colour as an option. Note the fully shrouded lead sockets. This gives increased resolution but slower update times for the digital display. The true RMS indication applies for symmetrical AC waveforms such as square waves and chopped sine waves (as from Triac circuitry) with a crest factor (ratio of peak to RMS value) of 3 for full scale readings and up to 6 for half scale readings. Since the AC volts mode is AC coupled, the 87 cannot give a true-RMS reading for any waveform with a DC component, such as a half-wave rectified sinewave, for example. feature which should be on all digital multimeters. Our reactions In this rather long review of the new 80 series we have really only given a summary of their capabilities. This is partly due to insufficient space and partly due to the fact that we have only been using them for a period of a few weeks. To really come to terms with these multi-featured multimeters, Battery life Another point in our wish list was battery life. The Fluke 70 series are pretty good in this respect, with a rating of 2000 hours. The Fluke 80 series, since they have so many additional functions, are inevitably not as frugal with the battery (a standard 9V type) and typically give 500 hours for the 83 and 85 models and 400 hours for the 8 7 model. The lesser value for the 87 is attributable to the backlighting feature for the display, enabling measurements to be taken in low light or complete darkness if necessary. By the way, those figures for battery life apply for an alkaline 9V battery. All models have an auto power off feature which undoubtedly is a fluke's new multimeters have a handy minimax recording mode which lets you monitor circuitry for faults. you would have to use them intensively for a period of months. However, in the time we have had the model 85 and 87 DMMs, we have formed some pretty strong impressions. And we have had them long enough to reveal any serious shortcomings, such as dicky resistance measurement or mickey mouse range selection switches. We can say that they don't have any serious problems nor would we expect any. They work very well as knockabout multimeters. We particularly like the positive rotary range switch, the easily read display and the rapid settling of the readings in all modes. We found that we pr eferred the bargraph analog display on the 85 model to the pointer on the 8 7. And we found the 85 a little more accurate in AC measurements than the 87. You'd expect this anyway from the specs. The feature we think could be improved is capacitance measurements. First, the range of measurement is not big enough. We'd like to be able to measure down to at least lOpF and preferably below. Second, measuring capacitors with the standard probe leads is tricky. How do you make reliable connections to capacitors and to resistors for that matter? Some meters of Asian origin have a special socket for such measurements so you can dispense with the leads entirely. We also think that the case should not be held together with self-tapping screws into plastic studs. For meters of this quality and price, machine screws and metal thread inserts are what is required. Apart from those points, the new Fluke 80 series work very well. We like them. We will probably buy one and maybe two for our own workshop. We like the 3-year warranty too - it shows Fluke have faith in the product. Presently they are expensive though, perhaps too expensive for the average enthusiast. But the new distributors for Fluke, Philips Test & Measurement, have some good news on that front and will be announcing considerably reduced prices, to take effect in early April. For further information, contact your local Fluke retailer. .! t APRIL 1989 61 THE WAY I SEE IT By NEVILLE WILLIAMS What's happened to wide-screen high-definition 3D television? Are you happy with the quality of the sound and picture available from a modern TV set? If not, would you be willing to pay two or three times as much for one with better sound, a higher definition picture, a wide screen format or a 3-D image? If a correspondent from Thornleigh, NSW had his way, that's what we could be facing somewhere down the track. Perhaps I should point out that th& letter in the panel was not entirely spontaneous. The position was that, when a decidedly vocal acquaintance got all stirred up about present-day TV standards, I backed off and suggested that he sit down and bash the keyboard rather than my ear! And so he did. lf you haven't already done so, it would be appropriate at this point to read the result of his efforts. You've read his letter? Good! I don't know about you but when somebody clambers on to the proverbial soapbox and proclaims to all and sundry what "they" should do, problems notwithstanding, I find it rather difficult not to assume the role of devil's advocate. The entertainment centre I still have on my shelves a copy of the Panasonic exhibition booklet issued in September 1983 and yes, I recall publicity to do with projection television and high-definition receivers by Sony, Toshiba, Philips and others, about the same time. That didn't happen by accident. Back in 1981, NHK (the Japan Broadcasting Corporation) and a 62 SILICON CHIP group of Japanese equipment manufacturers had unveiled a new HDTV (High Definition Television) system, based broadly on 1125 lines, 60 fields, a 5-3 aspect ratio and the option of picture tubes with much larger screens. Initially, HDTV called for a signal bandwidth of 20MHz but NHK was confident that this could be substantially reduced by sampling/encoding techniques. The real purpose of the exercise was not to launch HDTV there and then but to encourage group research and to grab for the Japanese electronics industry the initiative and the patents advantage that had long been held by the Europeans and Americans. The notion of a mini-cinema in the home has had plenty of exposure since then as, for example, in the "Sydney Morning Herald" Pink Guide section a few weeks back: "Bringing the cinema into the living room". It's a fine heading but how valid is the concept? I have no reservations about investing in the best TV receiver one can afford, or the best VCR and hifi system. Nor do I have reservations about bringing them together in one room as an integrated system, if that fits in with the viewing habits of the family. But the devil's advocate in me insists that it's quite another matter to base one's ambitions on the further assumption that the proper and ultimate role for a living room is as some sort of mini "Regent" fitted out and dedicated primarily to film and TV shows. About the last thing I'd want is for my own living room to be dominated by a 3-metre wide rack of electronic equipment. As a technical writer, I'm no less interested than W. G. in the technology of surround sound and high definition, wide-screen images. But unlike the aforesaid correspondent, I'm not impatient for its introduction and I don't feel deprived without it. The way I see it, Australian urban dwellers in particular are already well served in terms of audio/video entertainment. New technology, when? In due course, some of the developments sought by W. G. will undoubtedly become a reality but for new technology to be successful, it has to be right for the situation. The consumers must either need or want it, or be open to persuasion that they do. The providers must likewisP, be convinced that there is something in it for them. In the case of broadcast television in Australia, all three factors were present and TV won acceptance in this country at a record It's high time they adopted better TV standards! Dear Neville, Some years ago, National Panasonic set up a futuristic display at which we were invited to anticipate, amongst other things, a home "entertainment centre", where state-of-the-art viewing and listening facilities would be brought together tor realistic television sound and pictures. About the same time, Sony and others were carrying on about higher quality TV images with more lines, better definition and a wider picture format, using a wallmounted screen and a TV projector hidden in a coffee table or slung from the ceiling. The ultimate objective: "a cinema in the living room" . In newspapers and magazines, there was speculation about 3-D television being just around the corner. But what's come out of all this? We've got stereo sound, TV sets with bigger screens, Teletext and digital gimmicks, along with improved VCRs, all of which are fine, as far as they go. But where's the real progress? Our TV system is still shackled to the CCIR standards adopted in the 1950s and set in concrete with CCIR/PAL colour in the 1970s. Unless we break out rate, through the major phases of monochrome, colour and home video. But television has faltered at the DBS st/lge (direct broadcast via satellite) because, while there were potential providers and potential users, the Government opted for the radically new "MAC" format (Multiplexed Analog Components) instead of the. established PAL system (Phase Alternate Line) as used by all normal TV broadcast stations. With an eye to improved picture quality and possible future developments, the decision was not necessarily a bad one. However, the cost and complication of the new technology has drastically slowed the adoption of DBS in somewhere along the line, we'll carry the whole antiquated box and dice into the next century! It's high time that the Government and the electronics industry started to take the future seriously - to face up to the need tor more scanning lines and higher definition, a higher field rate to minimise flicker, the option of wide screen presentation and provision for extra video information to support some form of 3-D. Right now, the Government is debating pay-TV and that surely would provide an opportunity to break away from the CCIR yoke. On the assumption that pay-TV will be distributed by fibre optic cable and/or satellite , we should be able to provide tor better picture definition, better chroma information (eg, the Aussat/B-MAC system), surplus bandwidth for extra video components, more versatile sound signals - and a widescreen format. I imagine that new-release films would feature large on pay-TV and what would be more natural than to transmit them in that form? Sure, it would require a wide format film scanner. Live broadcasts would need wide format cameras and modified video tape recorders and so on . Australia, as originally envisaged. The notion of five nationwide networks and thousands of domestic satellite dishes sprinkled far and wide across the continent has simply not materialised. Nor is the Australian experience unique. Similar problem in Britain Readers of the British journal "New Scientist" may have seen an article by Barry Fox [October 22, 1988) detailing a somewhat similar hang-up in the UK. There, playing by the rules, the British Satellite Broadcasting consortium [BSB) had ordered a satellite from Hughes Aircraft in the USA, for launch in August 1989, with programs to begin in September or October. Sure, it would be expensive, as also would be the special receivers and video recorders that viewers would need to buy to take advantage of 21 st century TV. But who is going to support decent pay-TV anyway? People who can afford it! Others could change over as the price comes down . Existing viewers need not be shut out. In these days of digital processing and standards conversion , it should not be too difficult to process the incoming wideband wide-format signal in an add-on adaptor and reassemble it, minus the extra width , as a normal PAL signal for existing receivers. It should be possible for TV broadcasters to include a cueing signal to instruct a standards converter in the home on how best to crop any given scene. To receive pay TV, viewers are going to need some sort of a converter, anyway and an extra chip or two to provide cued standards conversion should be no great hassle. My point is simply that , if we continue to perpetuate the present standards by locking more ana more services into them, they'll still be entrenched long after many of us have ceased to care! W. G. (Wentworthville , NSW). Their plan was (and still is) to broadcast three pay-TV channels direct into British homes, using a MAC type signal format in the interests of improved picture quality and possible future developments. Unfortunately, the projected cost of MAC down conversion/unscrambler kits has escalated to the point where public acceptance of the service is no longer assured. In the meantime - as predicted in Fox's article - a Luxembourg owned satellite, Astra. was launched by a French Ariane rocket in December 1988, with the backing of Rupert Murdoch and others. Astra. however, is set up to broadcast 16 channels in normal PAL format. potentially accessible to British and continental viewers for a projected Al'll /1 . 1989 63 THE WAY I SEE IT - CTD outlay of about 200 pounds ($400) - the price of a 60cm dish and a relatively simple down-converter. But the overall picture is becoming somewhat murky. Initially, the four channels operated by Murdoch and additional channels by the retail chain W. H. Smith will be reliant on advertising and freely available to viewers having the necessary dish and down converter. Later in the year, however, Murdoch's special release film channels will be scrambled using the Palcrypt system, requiring the addition of a Palcrypt unscrambler, accessed by periodically renewable "smart" credit cards. The W. H. Smith channels will also be scrambled but using the Philips Eurocrypt system, requiring a further unscrambler and means of access. When the BSB satellite is fired up at about the same time, it will call for a second dish orientated 31 ° west instead of 19° east, a MAC down-converter and a Eurocrypt unscrambler capable also of handling MAC. As one writer put it: a British viewer seeking full satellite access looks like ending up with two dishes, three subscriptions and four adaptor boxes! So right now, the outlook isn't exactly bright for high-tech DBS in Britain. If W. G. is going to get his much prized wide-screen, high definition, surround sound television, he '11 have to come up with a more compelling reason than simply to make use of the technology we have before a discontented minority is too old to enjoy it! As for 3-D (3-dimensional) images, I can sustain the devil's advocate role without even trying. The basic idea of 3-D and possible ways to achieve it has intrigued would-be inventors for generations but the results have usually been a big yawn. The big screen option Let's solve that problem first and exploit our present CCIR/PAL standards to their logical limit. It will then be time enough to start stretching the screens even wider for those who want it that way. Even so, I still have my reservations about re-styling the living room into a mini-Regent! I can't quite remember the time, or the place or the format but my first exposure to large-screen UHF TV system update Right now, I'd suggest that theatre projection was quite an experience. Australian TV administrators and I do recall that I was rather an- viewers face a much more urgent noyed about the publicity which problem. I refer to the current resuggested that the large, concave deployment to the UHF band as it applies to the NSW Illawarra screen gave its own 3-D effect - a claim that could not be true of an (south coast) region. I had no sooner completed my image that lacked any basic 3-D information. reply to W. G. above than I received But while the fact remained, the · quite a lengthy phone call from a mood disappeared at the moment reader in the Wollongong area. the image flooded the huge screen While he mentioned his name, I am - as I recall, a panoramic shot not free to identify him beyond the from the nose of an aircraft flying fact that he has been well placed to low over a snow-covered mountain observe the emerging situation from the transmitting rather then vista. No sooner had we adjusted to the the receiving side. magnificent scene than the whole Reacting to rny remarks on the theatre tilted forward - or so it subject in the December issue, his seemed - and headed perilously one criticism was that I was still over a ridge into the valley beyond. tending to err on the side of caution. It wasn't 3-D but as far as the auHe emphasised that the saving dience was concerned, it was far feature of VHF transmission in the more compelling. moutainous terrain of the Illawarra Larger screens, if not huge region has been its ability to refract screens, are now routine in over hills, headlands and escarpcinemas and if one wants to in- ments to reach viewers in shadowcrease the impact of TV in the ed areas. home, larger screens are far more What's more, he said, it's still dopractical than any form of 3-D that ing so [at the time of the call) even has so far been devised. though the VHF service from the Given good source material and commercial station WIN-4 has been modern signal processing, I find the downgraded in terms of power and new generation of 70-odd cm pic- propagation, in preparation for the ture tubes most impressive and changeover to UHF. desirable - except for one thing. By contrast, the UHF transmitSome of them desperately need a ters, operating with 10 times or finer pitch colour screen to avoid more the ERP [effective radiated the situation where the once power) are leaving certain shadowtroublesome horizontal scanning ed areas "in a total UHF blackout". lines have been displaced as a proAccording to my informant, he blem by the visible vertical could name 21 spots in Wollongong phosphor pattern. where the UHF transmissions were The saving feature of VHF transmission in the Illoworro region hos been its ability to refract over hills, headlands & escarpments to reach viewers in shadowed areas. 64 SILICON CHIP simply not available from the new UHF transmitters nearby. Viewers in those areas have been receiving VHF signals, in some cases with very modest antennas; when the VHF transmitters are switched off, they'll get nothing. Further out, fading is every bit the problem mentioned in the December issue, except that it often amounts to complete signal loss. But that doesn't seem to have deterred some opportunists from nonchalantly installing UHF beams on the strength of political promises or a personal assurance that "she'll be right in the mornin' !" There seemed little doubt, said the caller, that DOTC planners had not only misjudged overseas experience but had persisted with the notion that, somehow or other, propagation problems could be swamped by extra power. It simply isn't working that way but, in his opinion, they've gone too far down the track to change direction. The only way that anything like the original coverage will be achieved is by providing a complex network of repeaters - maybe 30 or 40 more than originally envisaged. And that's going to cost! Five channels to consider! The way things are heading, he said, the three major commercial networks will ultimately gain access to this and other country areas by reciprocal arrangements involving existing rural broadcasters in this case, through the key stations in Wollongong (9), Canberra (7) and Orange (10). Having largely sat on their hands while WIN-4 has done most of the arguing, the networks will now have to put their money where their ambitions have been. In effect, every repeater installation will have to accommodate up to five channels: the ABC, SBS and three commercially based networks, with costs being shared. Multiply by five the number of repeaters envisaged by my caller and you end up with a startling number of receivers and transmitters sprinkled across the Illawarra area and, ultimately, most of the countryside. The question is whether the broadcasters will willingly wear this level of expenditure, especially for the smaller pockets of population which, to them, are statistically unimportant. My caller fears that they won't and that DOTC's only answer could be as mentioned on page 3 7 of the October issue: viewers disadvantaged by UHF will just have to rely on the satellite. But if the major commercial networks progressively gain access to all but a small minority of viewers by way of terrestial transmitters, why should they go to the expense of feeding the satellite? That will leave disadvantaged viewers with the option of a bill for $2500 to receive just the ABC and SBS. In other words, they will be well and truly up the creek with half a paddle! Two big questions remain: (1) will the VHF transmitters be switched off about the time you read this?; and (2) will the DOTC press on with existing plans for the NSW north coast in view of the Illawarra experience? ~ 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 for instant prices 4-HOUR TURNAROUND SERVICE Problems? ... and you don't have our .120page catalogue . .. At last . .. a TRADE catalogue for the consumer ARISTA ... your one-stop problem solver. Video plugs and sockets ... Video extension speakers . . . Video flyleads .. . Video RF interference filters . . . Video splitters . .. Indoor antennas .. . Video switching units . . . Down converters . . . Video speaker controllers . . . Video camera lights . .. Video tape rewinders ... Video cine adaptors ... Video head cleaners ... Video splicing kits .... Video storage cases . .. 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II I II~ - ~ ~ - op Selling 20MHz Dual Trace LABTECH Oscilloscope Sensation Save $199 This Month With This This Fantastic Offer ~ I - ~ A 2570 240V Mains Operated Ideal for "llve" recorclng, our NEW Auclo Mixing Console has truly sophisticated features: Normally $499 • PA mixing • Fantastic tape recording • Stereo/mono VCR recording • AIL 5 band' graphlc equalisers • Talkover facility • Separate headphone level control • Patch switch bank • Individual oontrols for Microphone, Phono 1&2, Aux. line 1&2, and Master slide level controls . This Month $399 You Save $100.00 Q 0155 Dual Trace Cro Two Q 0175 10:1 Probes ~ 998~ alu~ ....-- Normally $899 $99 Thi• Month Blend up to two magnetic or crystal tumtables, two tape deck• and two microphones -all at oncell FULLY PROFESSIONAL SPECS: $799 Free Yours_!~ $79!_ Thl~Month Only _J . Input · Mie 1: 0. 5mV, 600 Ohms, Mie 2 : 0.SmV, 600 Ohms (low Imp.), 2.5mV, 1OkOhms (low Imp.); Phono 1&2 (Mag.) 3mV, SOkOhms; Phono 1&2 (Cry.). 150mV, 100.0hms; Tape/Tenor 1&2 150m V, 100.0hms . Equ1ll•r 5 frequency bands: 60Hz, 250Hz, 1kHz, 4kHz, 12kHz • Boost Cut Range. plus a minus 12db <at> Increase YOUR SECURITY! ~-----------------7 . Infra Red Movement Detector , Multi Sector Burglar .-----7 I Pulse Count Type now includes pulse count circuitry with a specific I Our delayModel !RDpulse seming. pulses of IR radiation required to trigger dezctor. Providing detectors arc sensibly I positioned false triggering ia completely eliminated. I F,111u,.s: •Lens simply 'snaps' to either wide anile (range 40ft) for normal use or Narrow angle (and for corridor applk:allons. · I •Snazzy Integral mountlneplus) bracket allows corner 90o mounting. DC Powered I •12v •Built-In lest lamp. •Relay output SPST la max. I DC I s s301 Excellent value I at $79.00 · II 1989 time between the Three I Alarm arc the Prolect your Home or Business from Intruders with this "Slate ot the Art" Burelar Alarm System Over the Jut few years, House Break-Ins have inaeucd dramatically. Tbe recovery rate of stolen goods is very low. No w more than ever before, it makes extremely good sense to build and install this ingcni0111 Multi-Sectoc Syatem. This unique Alarm System incorporate, the features of the more expensive commercial models - at a fraction of thti price. 80ft 30V •9-t8V I I Features: • 8 sectors c:.on be mon)tored Independently • Each Input circuit ls provided with an lndlcator LED and a sector On/OIT swlk:h • Individ ual ,eclor Isolation • Inputs accept both normally clo,ed and normally open senoors • Two Inputs provided with an entry delay • Alarm Is disabled by fronlpanel key switch • Internal trip warnlne buu.er • Unique circuit detects tampering• Automatic muling otthe siren driver when under test I Fully variable exit delay • WIii drive external horn speaker • Alarm output variable between 1 & 15 minutes • When lrlegered, elves a connection to external devices e.e- Bells, TV Camera ek: • Swlk:hed output can be used lo send a silent alarm • Full battery back up • Alarm wlll operate tor approx. 2 days with mains disconnected • Supplied In an attractive tuncllona l security case. (See EA Jan/Feb'85) L-----------------~ Passive Infra-Red Lite Guard Floodlight Control Kit (Less Battery Back Up) K 1900 $149 .50 I I I I I I I $24.95 · _J L-----------------More TOP VALUE SECURITY KITS on our 2nd OPS I Back Up Battery 12V 1.2AH S 5065 How often have you thought there could be a prowler o.utslde your door? Install a Lite Guard & (once anncd) any "guest" will be floodlit wh::n detected by this highly sensitive Infra-Red Detector. Tiu: Liu: Guard detects a moving person or vehicle by comparing the background temperature with a rapid change of temperature across the detection beams. So when Litc Guard detect., movcJM:nt across the coverage area it will twn on the Ooodlight(s) for 1-20 minutes as prcadjustcd. Security: Prowlers are startled by an unexpected blast of light. Convenience: Ute Guard will detect your arrival & turn light on to we lcome you home. Energy Sav in g: Bu ilt- in photo cel l deactivates u nit in daylig ht. s 53so was $135.00 SPECIAL ONL V $99.00 Please note: Ploodlamps & holdc111 not supplied Flat Key Cam Lock .... ,1\ .. \ -·~ , ZiDc alloy die-cut b <J.lmg with ltaiDlcu llCcl cap. Key removable ill cuber po,ili00 . 2 1clid b..., koy• nwtJod. S 2550 WhRE $4.95 NOW ONLY $4.00ea S 2552 Spore Key D!a:,b $1.20 CL Telephone or Security Keyboard Switch Matrix Type · Spec!Ocallons: Contact Conductive rubber. Rating DC 24V• 5mA. Contact Rcsiatanoc 200 Ohms . Max. Withstand Voltage 250V AC. Bounce Sm sec. mu:. S 5380 WERE $9.90ea 10 up $8.90e:!. NOW ONLY $7.S0ea 150MHz Frequency Counter A frequency counter is invaluable for the accurate alignment and testing of many modern electronic circuits. This Is just a sample of our HUGE RANGE make sure you have a copy of our NEW 1989 Catalogue to check out our full range of meters and thousands of GREAT PRODUCTS. Specifications: Frequency Range !OHz - 150MHz Gate Time 1 sec, 6 sec. Accuracy +/· 1 c0Ull1 Max. Input 2JJV P-P Scnsitivity:l !OHz - 30MHz 25mV -!0OmV 110MHz • 150MHz !OOmV - 300mV I Power requirement 9V DC <at> !OOmA Use our 9V Plug Plck M 9004 Value at $199.00 Special $149.00 YOU SAVE $50 01520 IA- d-;- F - Digital Multimeter With Built-In Capacitance Meter from the Labtec:h range.: • Continuity Test • Buu.cr Sound: Leu than 200 obm • Capacitance: S Ranges 2000pP - 204P • Transistor Tc~tcr DC Volta&• ,2, 2, 20, 200, J0OOV DC Current 200uA, 2mA, 20mA, 200mA, 2A, JOA AC Voltage .2, 2, 20, 200, 750V AC Current 200uA,2mA, 20mA, 200mA, 2A, JOA Resistance 200, 2K, 20K, 200K, 2M, 20M ----7 I U IO reque ncy I G t I en era I All the normal ranges of cum:nt, resistance and voltage plus. convenient and simple to use capacitance meter in five ranges. plus transistor te,ter. Check the features of !hi> top quality digital multimclcr · I I I I j I General: Display: 3 112 digit LCD, o.5" height, with (See SC Feb'88) Will sense a door opening in a large or small room and will sound a two-tone chime. Does not have to be anywhore near the doorway as it detects pressure change. Ideal for use in shops, office, doctors surgeries, Chemists etc. K 1e15 was $45.00 polarity and LO-BAT indication• Ovenange Indication Maximum Common Mode Volta&•: SOOY peak Power: 9V alkaline or carbm-zinc battery. Dimcnsiom, Weight: 170mm x 87mm x 42mm, 350 grams Specifications: Input Impedance: 1OM on all ranges Normal Modo Noise Rejection: 46db at 60fh (!K unbalanced) Common Modo Noise Rejection: !OOdb at 60fh Overload Protection: !0OOV de or peak on all ranges Response Time: leH than 1 Second. , . .I ..RP. . . Q 1085 USUALLY $139.00 t-f!\!A ;I SPECIAL PRICE 99.00 - • - • • - ~* ~* ~f~ ~f~ LIGHT UP YOUR LIFE! K 1415 TOP VALUE $19.95 ILed Light:The House Number ~ cnclleBS fucinaticn u it sizzles and arcs. Supplied complete with AC Mains Adaptor. Price Breakthrough for '89 A 0120 $199.00 NOW PRICE SLASHEDTO $150 ~.~:f :,; , ,,. Add More Lib To Your Next Party Flashes in time to your music, or as norm.al strobe. Exclusively customised by Altronics into our H 0480 Instrument Case. Includes silk screened pone!. 8 Pi~ 14 Pin 16 Pin 18 Pin 20 Pin 24 Pin 28 Pin 40 Pin SIDQoth power for stereo, TV & computers. Altronics customised version housed in strong Jiffy Box. Nickel sprayed for EM! shielding. $75.00 For Increased Power Two Tube Option K 5795 $16.50 $15.00 (See EA Nov'87) Simply clips across the DC Fuse holder, Offers protection adjustable from 0-!0A in 2 ranges . Features: • Fast blow - slow blow setting. • Manual reset button. • LED fuse tripped indicator. • Operates off 1 single 9V battery (not supplied) • Two current Settings easily adjustable via a pot and calibrated scale. • Hollf'd in a rugged Jiffy Box. A must. for prototyping and service work. No Electronic workshop llhoold be without one. K2535 GREAT VALUE AT $39.50 LDT!4 Identify your House K 5790 $79.95 DC Electronic Fuse P 0530 P 0532 P 0534 P 0536 P 0538 P 0540 P 0542 P 0544 (See Silicon Chip Oct' 88) K6040 was $39.50 NOW ONLY $35.00 r;:Actlve --------7 Direct Injection ,Box I The LED light makes your house easily recognisable at night by illuminating your house number. Great for people visiting, easy for taxis and em~rgency services to locate you at night. Operates off low voltage plug pack • Automatic operation• Works only at night• Automatic switch off after 4-5 hrs . Altronic Kit comes complete. 64 LEDs supplied. K196o waa$59.95 NOW $55.00 1 I I I I(See EA Oct '87) Converts high impedance unbalanced inputs to Ilow impedance balanced outputs. Doz.ens of 1tudi<¥1'A uses . IFeatures: I• Sturdy dlecast Black toueh lndusL powder coat finish I•• Professlonally screen printed. box 1• Earth Isolate switch. • +Sdb pad. I•Phantom powering plus Internal 9V bat. K s550 $45.00 NOW $39.00 I I I Protect your valuable loudspeaker system. This easy to construct kit, provides both DC and overpower protection far your valuable Hi-Fi speakers. Self-powered unit discormects the speakers within 1/lOth of a second of a fault occuring yet in no way effects the sound quality. 1 unit rack box includes quality silk screened front panel. d K 5050 WAS $125.00 NOW $99.00 SAVE$26.00 C (SccE.A. March'88) Time your STD calls and Save Money. Timing is adjustable from 10 seconds to 15 Utility Timer ~ ., .... i' ," •• ' .' and silk sc.recned front panel. K1425 was 2 $ S.50 NOW 50MHZ Digital Frequency Meter (Sec EA May '88) Fantastic for Work Bcoch & Tool Box For Less Than $ 100 Easy to build. Over 50MHz in 5 ranges . 1 Features high input impedance overflow LED indicator. KHz & MHz LED Indicators. All components mount onto a single PCB. Complete with pre~ punched & silk screened front panel. Ideal for use in testing CB radios, 1V 's & AM Radios etc. $25.00 SAVE K 2510 (See SC Dec'87 er our '89 Cat for full spes.) High power rugged reliable design featuring low d~tortion and inbuilt speaker protection. All components, including output tnmistors mount on a single PCB. Suitable for high quality guitar amp. public address or in a high fidelity stereo amplifier. Kit includes angled beatsink bracket, main heatsink and unlike other kit suppliers, the In-Built Folyswitch for loudspeaket protection. Output Power: 1 OOW into 4 Ohms !SOW into 4 Ohms $99.00 VALUE (See SC Nov ' 87) Great for hand selecting exact values e.g. exact values for timer circuits $69.00 NOW$65.00 K $99.00 NOW$95.00 100W Version K 5140 150W Version 5150 (See SC Nov'87 Jan'88) TIIi.s !Uperb 1GHz. Frequency Meter will out perform many other instruments twice its price. F,-.atures: measurements up to 2.2uF. Plugs directly into your meter via inbuilt banana plugs. Kit includes prepunched silk screened front panel. Suits Labtcch Q 107S K 2520 W88 $24.99 I I I I I • Professional machined and screen printed red perspex front panel. • Easy to assemble . • Bright Hewlett Packard 8 digit display , • Electronic switch latching. • High performance IC',. • High Quality Components. Spe<lncallons Operational Modes: Period Freq. to !00M& Freq to 1GHz Freq. Range: IOOl!z-! Gllz (1.7GHz typ.) in frequency mode; l0Hz-2.SMH.z(SMHz typ.) in period mode. Gating limes: 0.01 ,0.1,1 and 10 seconds (10MHz & 100MHz ranges); 0.128,1.28,12.8 & 128 sec. (!GHz range). 2 NOW $20.00 SAVE!!! ~ ~ $299.o~~~$~ 9.o<:_SAV~$50.0~ J //l===========---=:::...:::=..;=..=c=':: Car Parking Proximity Detector (Sec Silicon Chip Jan'89) Ever reversed into a pafk.ing spot and hit th: car behind you? Well this proximity detector is the answer. A buzzer starts beeping and just before you hit the object the buzzing becomes continuous. Connects to your reversing light circuit, so it comes on automatic.ally every time you reverse. Effective range of about 1 metre. Complete with all parts, boxes and cable. K4310 .... MOST USEFUL KIT $34.50 NEW FOR '89 4LTilODIC) TELEPHONE DOUBLE ADAPTOR can be determined by the use of this dual range megohm meter . Ideally suited for checking bn:akdown in electrical wiring, appliances transformcn, automtivc genenton and altematcn etc. I Breakdown can be measwcd at either SOOY or 1 OO0V depending on tho required situation. K2sss Wo&ild suil ~Uctri.cians or l•cltniciaru work van, tool box or work b• rrch. Converts single telephone socket into a double 1ocket into a double socket to allow you to pl~f in two _P.hones. P 0995 ~.50 NOW LESS THAN HALF PRICE AT ONLY $2.00ea Manufacturers, Contractors and Bulk Users Please Contact Our Wholesale Sales Dept. Sydney (NSW Only) Colin Fobister (02) 437 4077 Melbourne (Vic/Tas Only) Brian Sorensen (03) 811 9967 Perth (W.A., S.A., OLD., N.T.) (09) 328 2199 174 Roe St. Perth W.A. 6000 PHONE TOLL FREE 008 999 007 Perth Metro & After Hours (09) 328 1599 ALL MAIL ORDERS P.O. Box 8350 Perth Mail Exchange W.A.6000 ALTRONICS RESELLERS Cha nces are the re is an Altron ics Rese llerright near you - check th is list or ph one us for detai ls of the nearest dea ler. PIHH Note: Rese llers have to pay the cost of freight and insurance and therefore the prices charged by individual Dealers may vary slightly from th is Catalogue - in many cases. however, Dealer prices will still represent a significant cost saving from prices charged by Altronics Competitors. Don't forget our Expre11 Mall and Phone Order Service - tor the coat of• local caH, Bankcard. YIN or Mntercard holdero can phone order for Nme day dnpatch. Blue Ribbon Da■f(lft are highlighted with a ■ These Dealers generally carry a comprehens ive range of A ltronic prod ucts & kits or w i ll order any required item tor you. WA STANDARDDELIVERYAPACKINGCHARGE$Ulllo1"9$7 1"9AUSTRALIA WIDE - We process your order the day rec:ei-i and despatch via. Australia Post. Allow approx 1 days from day you post order to you receiw goods $7.00 OVERNl~HT JETSERVICE - We process your order the day received and despatch via. 0 . . . . . . . , . - ~ fordeli-v next day Country areas plea:IB allow additional 24-48 houts. Weight limit 3Kgs (3Kgs COV99 !IS'!i, of Ordets). $10.00 HEAVY HEAVY SERVICE - All orders of 10Kgs or more must tnivei Express Road_ Please allow 7 days for deli-v. INSURANCE _ As with virtually every Australian supplier. - send goods at consignees risk. Should you require c o m ~ v e insurance coww against toss or damage please add l'MI to order value (mrnimum charge $1). When phone ordering please request "Insurance.. _ TOLL FREE PHONE ORDER - Bankcard.Visa. Mastercard _ . . can phone order toll free up to 6pm Eastern Standard Time Remembswithour 0 - . . . . . , . - w e deliver next day. COUNTRY ALBANY BP Electronics ■ 412681 ESPERANCE Esperance Commun1catoons 713344 GERALDTON KB El e ct r onics & Marine 212176 KALGOORLIE Todays Electronics ■ 212777 KARRATHA Daves Osc1tron1c 854836 IIANDURAH L ance Roc k Retravision 351246 WYALKATCHEM D & J Pease 811132 NT ALICE SPRINGS Ascom Electronics 521713 Farmer Electronr cs 52296 7 ACT CANBERRA Bennett Commercial Electronics 805359 Scientronics 548334 VICTORIA CITY All Etectromc Components 6623506 SOUTH MELBOURNE Winscott Trading 6995740 SUBURBAN CHELTENHAM Talking Electronics 5842386 CROYDEN Truscott El ectron i cs ■ 7233860 PRESTON Preston Electronics 4840191 COUNTRY BENDIGO KC Johnson ■ 411411 IIORWELL Morwell Electronics 346133 QUEENSLAND CITY Delsound P/ L 8396 155 SUBURBAN CAPALABA David Hall Electronics 3902399 FORTITUDE ·VALLEY Economic Electronics 2523762 WOODRIDGE David Ha l l Electronics 8082777 COUNTRY CAIRNS Electronic World ■ 5111555 BUNDABERG Bob Elk i ns Electronics 721785 GLADSTONE Supe rtroriics 72432 1 MACKAY Philtronics ■ 576855 ROCKHAIIPTONAccess E l ectron i cs I East St.) 221058 Ele c tr on World 2789 88 TOOWOOMBA Hunts Electronics ■ 329677 TOWNSVILLE Sole• ■ 722015 SA CITY 'e lectronic Comp & Equip . 2125 999 Forc e Electronic ■ 2125505 SUBURBAN BRIGHTON Force Electronics ■ 3770512 CHRISTIE& BEACH Force Elect r on ,cs ■ 38233 66 ENFIELD Force Electronics ■ 3496340 FINOON Force Electronics ■ 3471188 LONSDALE F o r ce Elecrro n 1cs ■ 326090 1 COUNTRY MT.GAMBIER South East Electronics 250034 WHYALLA Eyre Electronics ■ 454764 TASMANIA HOBART George Harvey ■ 342233 LAUNCESTON George Harvey ■ 316533 Nichols Rad io rv 316171 NSW CITY David Re,d Electronics ■ 2671385 CARINGHAH H1cam Unitronics 5247878 LEWISHAM PrePak Electronics 5699770 SMITHFIELD Chantron1cs 6097218 COUNTRY COFFS HARBOUR Gaffs Habour Electronics 525684 NELSON BAY N elson Bay E l ectronics 813685 NEWCASTLE Novocastrran l;tect Supplies ■ 621358 NOWRA E'w ,n g Electronics ■ 218412 RAYMOND .TERRACE Alback Electronics 873419 WINDSOR M & E Electromcs 775935 WOLLONGONG Newtek Electromcs ■ 271 620 VCR: Very Crook Recorder According to popular philosophy, we are supposed to learn by our mistakes. On this basis the cynic in me would suggest that I must be a very learned person because, in this game, there is plenty of room for mistakes. However, modesty for bids such an admission. This story concerns two General Model VGX-510A video recorders and two rather tricky faults which I encountered in them. One is a fairly routine fault, though more or less confined to this model, while the other may well have been a one-off. Nevertheless, it was a Very Crook Recorder. But before delving into the technical side of things, it might be helpful to list some of the brand names and cross company relationships which come to mind when this model is mentioned. And it is a rather complicated situation. First off, the General VGX-5 lOA is also marketed under the Palsonic label, model VCR-5000. However, the same deck is used in at least five other models: the JVC HR7200EA (for which it was originally designed), General Electric GEV6900, Ferguson 3V29A, Rank RV340 and some NEC models. So we have the same deck in at least seven different brands - a point worth noting for future reference. To make things even more confusing, the General machines have used parts from a variety of other manufacturers. For example, while. the VGX-5 lOA uses a JVC deck, the more recent General VGX-540A uses the the National NV-370 deck. In fact, the General organisation, having been gobbled up in some kind of a takeover, is now known as General Fujitsu. Well, so much for the corporate affairs side. Let's get back to technicalities. Mention of the JVC 70 SILICON CHIP 7200 might remind some readers that I dealt with a tricky problem in one of these machines some 12 months ago, in April 1988. Reference to those notes may help in following this story. I should also mention that most of these machines are now at least five years old. The first fault in the General VGX-510A showed up as damaged tape. More specifically, the tape was crinkled along one edge usually the Jower one - but in a few cases both edges of the tape were affected. The effect varied from machine to machine. In most cases it was minimal, probably because the customer sought my help early, but in some cases it caused tracking and sound errors. In any case, it was something which could not be tolerated, particularly if the machine was used to play hired tapes. My first attempts to cure this This photograph of the pinch wheel clearly shows the wear which caused fouling of the capstan. fault were a dismal failure. Having never struck it before I assumed that it was most likely a fouling problem; a build up of oxide on the various guide posts and rollers. And in fact, the build up was considerable. Unfortunately, a thorough cleanup of all these parts did little to alleviate the problem. Next I checked the various adjustments which I thought might have some bearing on the problem but found nothing suspicious. Puzzled, I put the machine to one side while l thought about it but before I could reach any conclusion, a second machine appeared on the bench with the same problem. Crook pinch wheel I decided it was time to ask for help. I rang the General service department and put the problem to them. The technician at the other end didn't hesitate: "change the pinch wheel". And that was it - he didn't elaborate and was so positive in his statement that I. didn't seek elaboration. In fact, he wasn't wrong but he'd left a lot unsaid. Anyway, I went ahead and ordered a stock of pinch wheels and when they arrived attacked the first machine. And this was when I realised the real nature of the problem. In order to replace the pinch wheel it is necessary to remove the cassette carrier assembly from above the deck proper and this gave me a much better view of both the pinch wheel and the associated capstan shaft. And that's where the real trouble lay; on the capstan shaft. It's not possible get a good look at this shaft when the cassette carrier is in place and it was now obvious that my attempts to clean it had been quite futile. To tell the truth, I hadn't paid all that much attention to it, previous experience being that this component collects very little oxide. So a token wipe, more or less blind, with alcohol soaked tissue was all it had received. Now that I could see it properly I realised that it was the worst case of fouling that I had ever seen. More to the point, it wasn't the conventional oxide fouling. There were two black rings on the shaft, the width of the tape apart and quite hard. The only place this fouling could have come from was the pinch wheel and this was confirmed by the manner in which the pinch wheel was worn. So the technician had been right but he had failed to mention the side effect of the worn pinch wheel; ie, the fouling on the capstan shaft. Anyway, I fitted a new pinch wheel and then tackled the capstan shaft. As I said, the fouling was a hard encrustation and while in theory it should not have been narrower than the tape width, some of the muck had crept into this area. Hence the tape damage. Getting it off wasn't easy. I hesitated to use excessive force for fear of damaging the capstan shaft surface yet initially it seemed impervious to the alcohol I normally use or the other solvents around the shop. However, it did yield eventually and I had a nice clean capstan again. And that was it. The machine behaved perfectly, with no hint of tape damage. The second machine also received the same treatment a.nd it responded similarly. Since then I have encountered the same problem in a number of these machines. Some came in because of tape damage, some for other faults but having learned my lesson, I give them all the treatment. At the same time, I take particular care to examine all other machines passing through the workshop for the same fault. Arising out of this exercise is the conclusion that this is a very serious problem with these machines, apparently due to the material used in the pinch wheel. Whether this was only a batch problem, or whether it will continue, I cannot say. All I do know is that every machine of this model should be ex- amined for this fault as a matter of course, regardless of any other fault. The other point is that, so far, this appears to be the only deck .with this fault. A few other machines have shown a hint of the problem but nothing like the gross fouling encountered on these. So there it is - I will be keeping a closer watch on all machines from now on. Fault number two So that was fault number one with this model. Fault number two turned up a few months later after I had treated several more machines for fault number one. In fact, it was for fault number one that this latest machine came in and I simply took it for granted that it would be just another routine job and quoted the customer accordingly. And that's all it was initially; exactly the same fault needing exactly the same treatment. It wasn't until I had put everything back together and given the machine a routine test that I realised that I still had problems. Sure, it was no longer damaging tape but there was a serious tracking problem wfrh noise bars on the picture and a problem with varying sound levels. For some reason this latter effect seemed to be worse on tapes which had been recorded on this machine, rather than on pre-recorded tapes. Even so, I wasn't particularly worried. I imagined that a normal setting-up routine, involving height adjustment of the guide roller assemblies, would be all that would be needed. It is a fairly straightforward routine, although it is a bit fiddly and time consuming. It is sometimes referred to as the "Interchangeability Adjustmenf'' CRO patterns The routine is basically the same for all machines. Some dismantling is involved to gain access to two test points normally located on the main board - test points five and three in this machine - and these are connected to the CRO. Test point five delivers an RF envelope pattern from the video heads while test point three delivers a 25Hz square wave which is used to lock the CRO timebase. The machine is then loaded and run with a standard colour bar tape. Assuming correct adjustment, r Q _J ·-== ==-----!' •' ol 0 ~ Q '".-0 'G, • o-() -·- ~A SOtl\~ MA~il-\~ G \ S I NVOL.Ve:t,•. . APRIL 1989 71 Envelope level is dropped at the beginning of track. I: : ::[::: J Fig.I: this line drawing and CRO pattern, from a National manual, illustrate a severe tracking error. A mirror image of this pattern may also occur. this setup should deliver a rectangular pattern to the CRO. If it doesn't, the height of the two guide rollers has to be adjusted until this is achieved. At the same time, it may be necessary to adjust the height and azimuth of the sound/ control head to give the best sine wave from the audio test tone on the tape. These adjustments tend to interact and may need to be repeated until both are correct. In greater detail, the CRO pattern displays the output froin the two heads and most importantly, the transition point where one head takes over from the other. In the case of a new machine (or a new set of heads), the output from each head should be an almost perfect rectangle and the transition point should be almost invisible (Fig.2). But if the tape is not tracking properly, or if the heads are worn, the rectangular pattern will taper off at one end or the other (see Fig.1). In fact, it's possible to recognise which guide roller should be adjusted according to whether the taper is to the left or right. Well, that's the theory and it usually works out well in practice. 72 SILICON CHIP Envelope is adjusted properly I I : L: I Fig.2: this diagram shows what the pattern looks like with correct tracking, assuming that the heads are in good condition. The result is sometimes less than perfect when the heads are worn and one must then settle for the best compromise and hope that the end result will be acceptable. If it isn't, a new set of heads is the only answer. Anyway, I went through the procedure and the CRO presented a perfectly acceptable pattern, at least initially. The snag was that the machine wouldn't hold this adjustment; while one watched, the rectangular pattern would suddenly drop at a transition point and noise bars would appear on the screen. I went over the procedure again but with no more success. Clutching at straws, I went through the sound/control head setting up routine. Significantly, it didn't seem to need adjustment and in the end had no worthwhile effect on the problem. Well, to cut a long story short, I went through the video head routine about umpteen times, interspersed with checks on any other components or adjustments which I felt could be important. I drew a blank all round. In the end I had to admit that I was going round in circles, getting nowhere. It was time to ask for help again. So I made another call to the General service depa rtment. This time I found myself talking to a Japanese technician who seemed t0 be particularly well versed with this machine. He listened very carefully to my explanation of the problem and the steps I had taken so far, checked whether I had done this or that, and was finally forced to admit that I had done all the right things. More to the point, he couldn't think of anything else that I could try. In short, he wa s as puzzled as I was. In fact, he went so far as to say that, considering the age of the machine, it might be more economical to write it off, rather than chase such a difficult fault. I did raise the matter of the guide roller assemblies but he was most emphatic that he had never encountered any problems with them. As far as he was concerned, the guide rollers simply did not give trouble. It's all there is So I was back to square one. I put YOU NEED THIS TV TEST EQUIPMENT Slant pole Guide roller Supply pole base ~ 0 Supply loading ring Pin slide ring SHORTED TURNS TESTER Including meter for checking EHT trans, yoke windings, drive trans. $78.00 + $3.00 P&P HI-VOLTAGE PROBE Fig.3: the guide roller assembly and its relation to the loading rings. Additional information on this assembly was published in the April 1988 issue . Including meter Reads positive or negative 0-50kV For TVs, microwave ovens and high voltage equipment $84.00 & $5.00 P&P the machine aside again until I could spare the time to really get stuck into it. In the meantime my thoughts kept coming back to the guide roller assemblies; I couldn't shake off the idea that this was all there was left to suspect. Eventually, I found time to set everything up as before and repeat the adjustment routine once again. Initially, the results were exactly the same. The breakthrough came when, more or less on impulse, I applied gentle pressure with the blade of a screwdriver to the top of the guide roller assembly on the supply reel side. The result on the CRO pattern was immediate and I found that judicious pressure could produce and maintain an almost perfect pat- The Very Crook Roller which caused the trouble . While known to be faulty, no slackness could be detected in the assembly. tern. But once I withdrew the driver, we were back to square one again. I wasn't sure whether this was normal or not, so I tried the same tactic with the guide roller on the takeup side. The result here was quite different. Short of applying extreme pressure, it had virtually no effect. From this I assumed that there was some slackness somewhere in the suspect guide roller assembly. Yet try as I might, I couldn't pinpoint it. All I had established was that one roller responded to pressure and the other one didn't. The only way to prove the point was to replace the roller. Well, that seemed simple enough - I thought. I turned to the manual to find the appropriate part number and realised that the assembly, as such, was not listed. Each component of the assembly - there were seven in all - was listed separately with its own part number. Fair enough; all I had to do was list these numbers and ask for the complete assembly which comprised them. And that was the first barrier. I rang the spare parts department, told the assistant what I wanted and dictated the part numbers to him. He asked me to wait on while he punched them into the computer, then announced that, as far as the computer was concerned, there were no such part numbers. Mentally muttering "Don't be Uncle Willie", I made the more diplomatic suggestion that perhaps he should check further, as the part numbers were listed in the manual. The upshot of this was that he pro- TV TUNERS (PHILIPS) ECL 2060 Repair or exchange UV461 Repair only $17 .00 ea + $2.00 P&P CHEQUE, MONEY ORDER, BANKCARD OR MASTERCARD TO Y.V.TuNERs) 216 Canterbury Road Revesby 2212, Sydney, Australia Phone: (02) 77 4 1154 SALES CAREER IN ELECTRONICS Suit bright young electronics enthusiast 19 to 24 years. The wholesale division of Altronics has opened sales offices in Sydney and Melbourne. We have a position in each city for a sales person who fits the following: ( 1) Is a pleasant person who gets on well with others. (2) Wants to "get on" in life & possesses self-motivation. (3) Has own vehicle - we will pay a generous mileage allowance. (4) The position will involve regular calls to clients (ie, electronics firms, manufacturers , contractors and resellers), as well as office operations; eg, handling telephone enquiries, sales and the like. The successful applicants will be 2nd in charge to the state manager in each city. A generous salary and commission system applies. Sydney applicants call Colin Fobister 437 4077. Melbourne applicants call Brian Sorensen 811 9967. AL TR0NICS DISTRIBUTORS PTY LTD, Dynamic suppliers of electronic products and components. 174 Roe Street, Perth, WA 6000. APillL 1989 73 may be a one-off event. Ifso, that's fine. But the mere rarity of. the problem is itself a hazard; there is nothing on record which will help. Let's hope this story rectifies that. And who knows; it might even save a machine from being written off. SERVICEMAN'S LOG Foreign bodies .. . r \ H-~Ve: 'De:s~R\'8~ A VA'R\E:"'t"{ OF FOR~lGt\l "BODIES I HAV~ F\~He:'D ovr OF mised to look into it and ring me back. And he was as good as his word, except that the call came not from him but from the Japanese technician I had spoken to earlier. Not realising who I was, he started out by explaining that they didn't keep this assembly in stock. (I assumed that this was a continuation of the previously expressed idea that they never needed to be replaced]. Then he went to enquire why I needed this assembly. At this point I reminded him of our previous discussion and explained that I was now virtually certain that a faulty guide roller assembly was to blame. And I gave him a detailed account of what I had done. My experience obviously came as a surprise but having listened carefully to all I had done, he seemed to be convinced that I was on the right track. On the other hand sup74 SILICON CHIP v,~ RECDR~S plying a replacement was still a problem. In the end, he said, "Leave it with me, I'll see what I can do". So we left it at that. Sure enough, a couple of days later a replacement assembly arrived in the post. I have little doubt that it had been raided from another machine, probably one written off for some other reason. I lost no time in fitting the new assembly and going through the whole setting up procedure again. And to my immense gratification, it worked. The CRO pattern was rock steady and the picture completely clean. So I'd not only cured the problem, I'd proved my point and found a new meaning for VCR: Very Crook Roller. I have no doubt that the technician was being perfectly honest when he said that there was no history of failure; which is why I suggested at the beginning that this And now here is something in lighter vein. On a number of previous occasions I have described a variety of foreign bodies that I have fished out of malfunctioning video recorders; parts of children's toys, coins, matchsticks, beads and so on. So what was there left? Read on and see if you can top this one. It all started with a phone call from a lady who explained that she had a new Panasonic (National] video recorder which had performed perfectly for the first few months but was now giving trouble. She was somewhat vague about the exact nature of the fault but I gathered that it was basically a loading problem and there was something about a loop of tape remaining after a cassette was unloaded. Anyway, I suggested she bring the machine in and we would give it a once over. She then raised the matter of warranty, pointing out that, as the machine was only six months old, she assumed it would still be covered. I assured her that this was so. So, a few days later the lady pushed the off ending machine across the counter. It turned out to be a Panasonic NV-G40, a very recent model featuring remote control and digital scanner, though I'm not quite sure what the scanner is supposed to scan; I have yet to see any published programs featuring the required bar pattern. But that point aside, I was a little concerned because this was the first model I had encountered at service level and I had little technical information on hand. Fortunately, I soon realised that this machine uses the same deck as many earlier models; right back to the model NV-G20 in fact. Later that day, when things were a bit slack, I decided to at least try the machine and clarify the exact nature of the fault. So I set it up on In this case the loading had not proceded far enough to leave a loop of tape outside the cassette but I imagine that it was a variation of this routine which had created a loop on at least one occasion when the customer used the machine. If the loading had proceded a little further before the cassette was rejected, this could well have happened. And in view of what I subsequently found, it is quite likely that the fault varied from time to time. But right now, I didn't have a clue and what I had seen didn't inspire me with a great deal of confidence. It conjured up visions of a faulty mode select switch or something equally complex in a machine with which I was only partly familiar. In any case, it looked like a job that would have to be put aside until I had more time. the bench and pushed in a cassette. Initially, all seemed well; the cassette carrier accepted the tape and, apparently, set it down on the deck. But then it rebelled and promptly unloaded the cassette. Well, that was a new one on me. Fortunately, this machine is very easy to get at; only four screws need be undone to release the cover and this reveals both the deck and the main printed board, which sit side by side. That done, I tried loading the cassette again. And now I could see that the process went as far as putting the cassette on the deck and starting the actual tape loading process. In this machine the loading process differs somewhat from the more usual arrangement. Instead of waiting for the "play" instruction before extracting the tape from the cassette and wrapping it around the drum, this machine begins extracting the tape as soon as the cassette reaches the deck. It doesn't go all the way. It extracts enough tape to allow it to be loaded against the audio/control head. The idea appears to be to provide better tape control during the subsequent loading process, though I have not worked out the details of this. Anyway, this was where the loading process baulked. It began this first stage but before it could complete it, the cassette was unloaded. Hairy legs So I contented myself with extracting the cassette from the carrier and giving the deck assembly a quick visual inspection. And that's when I saw it. It was on the deck, to the left of the supply reel disc, hard against the front of the machine and partly hidden by the cassette carrier assembly mounted above the deck. "It" was a very large tarantula spider and, initially, I wasn't sure whether it was dead or alive. This didn't worry me particularly as tarantulas are quite harmless. As it turned out he (or she) was very dead and I was able to fish him (or her) out without too much trouble. There were also a couple of spare legs lying around which I also recovered. Thus inspired I gave the rest of TETIA TV TIP Philips K9A Symptom: Grotesque north/sou!h distortion. Picture height normal 1n the centre of the.screen but reduced to almost nothing at the sides. Cure: Broken track between N/S adjust trimpot R602 and the N/S transductor. This break forces the whole vertical scan current through the transductor, instead of sharing it with the adjustment network. the deck a thorough inspection, removing the cover above the head drum in the process. This would have been done anyway, since I make it a policy to give all tape-path components a routine clean regardless of the main fault. I also wanted to make sure there were no more beasties involved. There weren't as it turned out but I was surprised at the condition of the head drum. The working face was reasonably clean, although there was some oxide build-up on the guides and auxiliary heads; rather more, in fact, than I expected in a new machine. But the real surprise was the amount of muck on the top of head drum. This took the form of a sticky coating and a pattern of spots; the latter, I assumed, being excreta from the now departed tarantula. Anyway, I cleaned everything up, including the oxide build-up, then put the machine through its paces again. And that was it; everything worked perfectly. I can only guess as to the exact manner in which the corpse was gumming up the works and I can't even be sure that it was exactly the same on my bench as it was in the customer's home (it may well have moved around in transit). It might have been fouling the brake mechanism and the machine sensed this fault and refused to accept the cassette for this reason. Another query concerns just how the monster got into the machine. Like most such devices, it is well enclosed but there are ventilation slots in several places, some of them a little wider than typical. And knowing just how small a space these creatures can negotiate, it wouldn't surprise me if this was the explanation. Alternatively, it is just possible that it gained entry via a cassette, there being two large pockets on the underside which could easily accommodate it. Technically, that was the end of the story. However, I had to inform the lady that the warranty did not cover the entry of tarantula spiders into the machine, so I would have to charge her. Fortunately, she accepted this philosophically. So what will we find next? -~ APRIL 1989 75 FIX THAT CLOCK!!! TICK, TOCK KA· 1109 Electric Fence KA-1115 300W amp module KA· 11 16 300W power supply KA· 1117 300W speaker protector KA-1119 Transistor tester KA-1220 Signal tracer KA· 1230 Zener diode tester KA, 1390 Freq . counter 50MHz KA- 1392 Prescaler 500MHz KA- 1428 Function generator KA-1430 Vocal canceller KA-1452 Sutmoofer Amp KA-1505 TAI Hall effect KA-1506 Transistor asst ignition KA-1 508 Touch light dimmer KA- 1522 Gu itar effects BBD KA-1535 Ign ition killer KA-1550 Deluxecara larm KA· 1556 Ultra sonic move det KA-1574 30V 1A power supply KA-1582 House alarm KA-1595 Digi tal capacitance meter KA-1598 40W inverter 12/230V KA-16 10 300W inverter 12/230V KA-1630 12V lamp flasher KA-1635 AM/FM stereo tuner KA- 1636 AM/FM remote control KA· 1650 Playmaster 60/60 KA-1652 Blueprint 60/60 KA-1660 Electric fence KA-1675 Screecher car alarm KA-1677 Audio oscillator (metered) KA-1681 3 band short wave radio KA-1682 Dual track power supply KA-1683 Battery mon itor KA· 1690 DI box KA· 1691 TV colour ba r/pattern gen KA· 1692 Voice operated relay KA-1693 Metronome KA· 1694 Volt/continuity test KA-1695 AC/DC Millivoltmeter KA- 1696 Econ. Temp probe DMM KA- 1697 Utility timer KA· 1698 Tran . FET, Zener test KA-1699 Bench amp· signal trace KA-1700 Power transistor tester KA- 1701 RF detector probe KA-1702 50M Hz Dig Freq meter KA-1704 FM Receiver KA-1705 Stroboscopic Tuner KA-1706 Cheap capacitance meter KA-1707 Powermate 2 KA-1708 Supertimer KA-1709 PC-driven Function Gen KA- 1710 Beepo Continuity Tester KA-1711 TTL-analog Video Convert KA- 171 2 PCB Shorts Locator KA-1714 Beat Me Metronome KM-30 15 Li stening post KM-3030 Ultrafidelity preamp KM-3040 Dual speed modem KM-3042 Speec h synthesiser KM-3044 6000 Mosfet Module KM-3046 Super Simple Modem KM-3050 Workhorse amp $23.50 $1 19.95 $105.00 $23.50 $21 .50 $27 95 $16.95 $169.50 $46.50 $129.50 $24.95 $134.50 $44.95 $42.50 $29.95 $115.00 $23.50 $89.50 $34.95 $89.50 $169.00 $85.00 $99.95 $269.00 $1295 $599.00 $9950 $329.00 $369.00 $59.50 $34.95 $165 00 $79.50 $129.95 $14.95 $39.95 $159.00 $24.95 $19.95 $29.95 $46.50 $19.95 $21 .95 $55.00 $39.95 $22.95 $13.50 $79.00 $55.00 $47.50 $16.95 $119.00 $59.00 $49.95 $1995 $49.95 $22.95 $29.95 $39.95 $359 00 $169.00 $43.50 $119.00 $85.00 $35.00 KM-3056 100W module less MFets KM-306 1 Microphone preamp KM-3063 Uo satellite decoder KM-3064 Octave EO mod KM-3065 AS true 232 interface KM-3068 FM minder bug KE-401 4 Mixer preamp KE-4023 Signal Spkr protector KE-4029 NiCad battery charger KE-4033 Temperature probe KE-4050 ETl480 SOW amp module KE-4052 ETl480 100W amp mod KE-4048 ETl480 power supply KE-4200 5000 power amp KE-4666 RS232 Centronics inter/f KE-4690 ETl342 COi KE-4698 4 sector house alarm KE-4711 Mini FM transmitter KE-4722 AS232 Commodore KE-4724 Parametric eq uali ser KE-4725 Solder iron tem p control KE-4729 Guitar preamp KE-4730 Solar gen p/supply KE-4731 Telephone intercom KE-4733 Active Crossover KC-5010 Capacitance meter KC-501 2 Car radio power supply KC-50 13 1GHz Digi Freq meter KC-5015 Telephone ringer KC-5016 Speed control/dimmer KC-5017 24 to 12V converter KC-5019 100W amp module KC-5021 Protector car alarm KC-5023 Low ohms adapt DMM KC-5027 Ph meter KC-5028 Train controller KC-5029 CD H/phone amp KC-5030 High Energy Ignition KC-5031 Optical tacho KC-5032 Di sco Light KC-5033 Studio 200 Preamp KC-5034 Remote for Car Alarm KC-5036 Wireless doorbell TX KC-5037 Wireless doorbell RX KC-5038 Universal power supply KC-5039 Vader Voice KC-5040 Speaker phone KC-5041 Mini Mitter KC-5042 Kn ightrider LEDs KC-5043 120W PA/Guitar amp KC-5044 Car Safety Lights KC-5045 Poor Mans Plasma KC-5046 Mains Muzzler KC-5047 Beta Tester KC-5050 1/3 Graphic Equali ser KJ-6502 Syntom drum synth KJ-6504 8 cha nnel mixer KJ-6505 Console Psupply above KJ-6535 2010 10 band stereo Eq . KJ-7000 Red light flasher $79.50 $36.95 $55.00 $59. 95 $27.95 $11 .95 $39.50 $22.50 $14.95 $32.95 $27.50 $34.50 $2950 $499.00 $32.50 $79.50 $29.95 $9.95 $16.95 $23.50 $39.50 $45.00 $12.95 $49.95 $39.95 $27.95 $28.95 $299.00 $1995 $18.95 $59.00 $38.95 $79.50 $29.95 $49.95 $89.00 $24.95 $49.95 $49.95 $159.50 $229.00 $79.50 $1 6.95 $4250 $12.95 $19.95 $89.00 $34.95 $17.95 $72.50 $29.95 $49.50 $55.00 $18.95 $239.00 $42.50 $595 00 $119.00 $169.00 $19.95 t<//4.er-e ;er-/01''/ffalfee 1~ Mea.ft<l"edllf l"e.fa.lt.f If you're tired of looking at that mantle clock reading ten past one (and it's not). why not fix itl It wi ll take you about 10 minutes with one of our clock modules. We have four types. Just remove the old mechanism, throw it in the bin and replace it with an accurate quartz crystal movement! We even have ones that play the old fa shioned tune (Westminster Chime) and then chime the hour. Also ideal for making your own custom clock face. STANDARD MOVEMENT • Very compact 56 x 56 x 15mm • Powered by 1-AA battery • Suppli ed with 3 different sets of hands Cat XC-0100 10 for $2 100 for $15 1000 for $110 PENDULUM MOVEMENT/QUARTZ CLOCK Cat XC-0103 Mid Size Spade Lugs ~ After many requests we now have the 4.Bmm spade lug, in between the sta ndard site (6.3mm) used on cars . woofers etc .. and the baby one (2 5mm) used on tweeters. . Cat. PT-4522 acket of 8 $1.50 $16.95 MELODY CLOCK MOVEMENT Two different modules are ava il able. Both chime the hour after playing their tune. XC-0 106 plays Westminster ch imes each hour then gongs the hour (i.e. 7pm • 7 gongs) XC·Ol 07 plays a different melody each hour, then gongs the hour. Both units are supplied with: • Clock movement • Speaker and battery holder (3-AA batteries required) • 3 sets of hands Cat. XC-0106 Westminster chimes Cat XC-0107 12 melodies ONLY $19.95 each 12V CAR ANALOGUE CLOCK MOVEMENT MASSIVE SCOOP PURCHASE! Convert the broken/unreliable or inaccurate mechanical clock in your car to space age precision. Made in West Germany by VDO, the module measures rough ly 45 x 38 x 40mm deep. The compac t size virtually ensures that it wi ll fit in any space I Quantity strictly limited. Cat XC-0106 ONLY $~.95 PUBLIC NOTICE The 1989 Jaycar catalogue was inserted in the March issues of 'Electronics Australia' and 'Silicon Chip' magazines. The issues of these magazines that were se nt to Dick Smith Electronics had the catalogues with them. It appears that the same issues were either sold by DSE or given gratis DID NOT contain a Jaycar catalogue. If you received a copy of 'EA' or 'SC' for March from DSE and it did not contain a Jaycar catalogue, please call in to any Jaycar store for a FREE COPY of the cata logue. Jaycar would like to take th is opportunity to pledge to our customers that all magazines sold by us co ntain ALL the material supp li ed by the magazine publi shers including competitors cata logues. We are not frightened of competition! Regards, Gary Johnston.Managing Director, Jayca r Pty Limited. Relay Easily wired into your ignition to ki ll it. thereby foi ling the thief and making the vehicle near irnµossible to steal. Rated at 30 amps. Cat. LR-8840 $12.95 $12.95 Idea l clock mechanism replacement for a small pendulum clock, or create your own pendulum. • 3 sets of hands suppli ed • Uses 1·AA battery TAG TANTALUM BARGAIN Ignition Kill We have about 20.000 pcs of a 4.7uf 16V tag tan talum made in West Germany. Normally worth 75t each. Grab yoursel f a bargain Cat. RZ-6636 i ~ LED Bargains We have secured a small quantity of different style LEDs. There are two types, both well below normal prices. f-:::YV -i~'.- +. · Style 1 Red 5mm x 5mm Cat. ZD-1761 40~ ea 10+ 35~ ea Green 5mm x 5mm Cat. ZD-1762 40~ ea 10+ 35~ ea Style 2 Red 5m mwith an extended centre Cat. ZD- 1747 20~ ea 10+ 18~ ea Green Srnm Cat. ZD-1748 15~ ea 10+ 12~ ea Sta nley Brand Limited quantities of both N ~-fJ /, 1 ., cftt'f P~ieu, 8" (200mm) PLASMA LAMP Quality Disks at The most beautiful thing we have ever seen. Another Jaycar direct import. Would you believe - computer disks with a LIFETIME GUARANTEE for less money than you have ever had to pay before! Just imagine, a beaurnul plasma display in your own home for under $2001 Watch as the red glowing element In the centre of the 200mm glass sphere projects beaurnul blue lightning outwards to the inner surtace of the ball where tt magically changes back to crimson. This event occurs simultaneously at least 50-100 times all over the inside of the spher is constantly in motion. · It is truly beaurnul to watch. The intenstty of the display can be controlled by a slider pot mounted on the attractive base. In add ttion you can trigger the performance by 51/4" DSDD 48TPI DOUBLE SIDED/DOUBLE DENSITY Cat. XC-4730 $6.50 for 10 31/2" MF2DD 135TPI DOUBLE SIDED/DOUBLE DENSITY Cat. XC-4736 $26.95 for 10 51/4" DSHD 96TPI DOUBLE SIDED/HIGH DENSITY Cat. XC-4732 $18.95 for 10 means of a sensitive sound All disks are supplied with envelope, index labels and write-protect tabs. Remember, these disksight be cheap ut they are good quality. We are so impressed by the quality we are happy to offer a lifetime guarantee. activated circutt. The entire unit comes with tts own dedicated power supply and is packaged in an attractive gift carton. This beautrrul instrument will give countless hours of pleasure and relaxation and is tru ly unique. Cat. XP-1000 ETCHANT CHEMICALS IN JARS Low Cost Telephone Answering Machine This machine is super simple to use I Only one button and the on/off switch controls the unit. All other functions are automatic. At this price you can afford one at home, at work (may not operate on some PABX systems)- even in your car! ANN Ree Cat. YT-7020 . , .- . (Unde, Cossette Doo,J $199 $139.50 :,~ i", ...._ le- Se-1(.fathl(al 30 PIECE ENGINEER'S DRIVER SET At lastl A driver set incorporating those obscure sha ped heads! Have you ever needed to service an electric tool? Chances are you would not have been able to do so because the screws holding the appli ance together had strange sha ped heads. Well now you can with our 30 piece driver set! Thi s set contains all the driver bits you are EVER likely to encounter (See Below). Basic to the set is an 8 1/2" Chrome-Vanadium driver which will accept any of the 28 hardened steel bits supplied. All held in the socket by a sma ll magnet - so you ca n use it in any position. The screw-together hollow handle will hold several tips so you don't have to take the whole set with you into the field. There is a tip here to suit almost any screw/nut you may come across. Here's what you get: • 5 Slotted Bits 0-1, 3-4, 5-6, 8-10, 12 • 5 Hex Bits 3/32", 5/64", 7/64", 1/8'', 9/64" • 4 Philips Bits No. 0, 1, 2 & 3 • 4 Square Recess Bits No. 0, 1, 2 & 3 • 6 Torx Bits T10, T15, T20, T25, T30, T40 • 2 Pozidrive Bits No. 1 & 2 • 1 x 1/4" Drive Socket Adaptor • 1 x 1/4" Drive Hex Bit Holder And its all housed in a sealable tough plastic case. Cat. T0-2000 $19.95 PLAYMASTER/ JAYCAR 60/ 60 BLUEPRINT AMPLIFIER Standard Version still available Cat. KA-1652 $369 Cat KA-1650 $329 FERRIC CHLORIDE 200g Cat. NC-4251 $4.95 400g Cat. NC-4562 $7.95 AMMON IUM PER SULPHATE .. - Message light Safe for storage, childproof lids - safe from kids. no mess. no fus s FF \-OlUME 400g Cat. NC-4254 $6.95 12V DC - 240V AC Sine Wave Inverter The Jaycar Sine Wave Inverter is a high efficiency, high speed Mosfet transistor design! Considerable appl ied research went into many aspects of this project - especially high current. high freq uency transformer construction. Using switchmode technology an accurate 50Hz 240V sine wave is generated from a DC source commutated at around 50Hz. The weight savings and efficiency over square wave types is staggering! We are very proud of this Australian made and designed product. SPECIFICATIONS • Output power<at> 12V DC - 300VA max • Current draw<at> 1,:V DC. 300VA - 35A max • Efficiency 90% (yes. 90%)<at> 1OOVA load 78% full load • Max sine wave distortion <5% (resistive load) • Frequency drift better than mains grid • Dimensions 260(W) x 220(0) x BO{H)mm • Standby current drain 500mA (auto power on) • Power down mode zero current draw Accessori es: supplied with 2 heavy duty lug terminals, brass nuts and bolts. spare 40 amp fuse. Specifications subject to change without notice Cat. Ml-5020 $449 6 Way Power Outlet with Mains Filter Not only is it a 6 way power board, it incorporates a voltage surge and spike protector and noise rejection filter network. Supplied with two metre cord and mains plug, sa fety shutters on each outlet, illuminated master on/off switch and even a safety circuit breaker. Cat. MS-4030 $64.95 UPGRADED 5000 BLACK MONOLITH POWER AMP RE-BORN WITH TOPOLOGY MODULES Cat. KE-4200 $499 NOTE: If you requ ire absolute mains suppression don"t forget our Australian made Squeaky Clean Mains Filters. ORTASOL GAS After many requests. it's now available. Actual Portasol brand gas in 150g can. Ideal for both Portasol gas soldering irons. Cat NA-1020 ONLY $6.50 3M Brand Pure Copper Foil Adhesive Backed 12mm wide x 18 yard s (approx 16.2 metres) long. Idea l for RF screening. macro repair of PCB's. Flat heavy duty conductors or under floor speaker wiring. Will take 35 amps. Very small quantity available 50% below cost. $20/roll Machined Aircraft Grade Aluminium Flashlight NBELIEVABLE SOLDERLESS LUG PACK ) Another surplus buy. A bag of approximately 200 assorted insulated solderless terminals. Included are ring terminals in many different sizes, lug terminals, cable joiners, and solderless lugs to connect into terminal block. These normally cost between 15 and~ each. We estimate the normal price for these parts would be around $50. i. LIMITED QUANTITY Cat. HP-1210 ONLY $9.95 ONLY $10 What an excellent product! It measures 145mm long and runs off 2 - AA batteries. It is 70 times brighter than a normal torch and the beam is adjustable from spot to beam. and it's waterproof and shockproof. Durable anodised abrasion resistant finish, with a non slip knurled grip. This torch will last a lifetime. Small enough to fit inside a car glovebox or handbag. It can also be used as a lantern. Unscrew the top and the bulb is exposed to give 360° light. We have seen these torches for $19. We have direct imported them and can offer them for the amazing price of only $9.95. Cat. ST-3000 Spare bulbs available for only $1.50 (Cat. ST-3002) That's only&~ each? Picture represents a typical pack PERSONAL DATABANK/ CALCULATOR - UNDER $40 This personal databank will store your telephone numbers as well as being a pocket calculator. The databank has 2K memory which is 1,936 characters which will accommodate more than 100 names and telephone numbers. It measures only 88 x 57 x 4mm thick, about the same size as a credit card,41·aIso has a special security code, so those private phone numbers can't be retrieved by anyone but you. National Semiconductor 741.S/ S/74 .. rn Logic Data This book gives full specifications on all TTL devices (whether LS, Sor ordinary 74 series) from 7400 - 900 part numbers. Over 820 pages, 170 x 230mm, Softcover. Cat. BN-4008 $19.95 National CMOS Logic Data Book Once again we have stocks of this favulous data book. Components ct11ered in the book include: • 74HCQQ series • 4000 series • 74COO series CMOS application notes and surface mount diagrams. Approx. 1450 pages. Cat. BN-4004 Other features include: • Auto power off • Edit feature • 10 digit calculator • Includes battery We have seen these for as much as $79.95. But with our direct importing we can offer them at about 1/2 that price Cat. OM-7200 DIGITAL THERMOMETER Forget those old mercury thermometers. This new digital thermometer will read in both Celsius and Fahrenheit. Celsius range 32o-43o. Farenheit range B9.6o-109.4o. Also includes buzzer alarm. We have seen these in other catalogues for as much as $29.95. Jaycars direct importing cuts out the middleman and you SAVE MONEY. Cat. OM-6300 ONLY $14.95 PASSIVE INFRA RED DETECTOR PRICE BREAKTHROUGH Features & Specifications • Dual element pyroelectric sensor • 24 dual element detection zones in three layers • Wide angle 90° multi layer coverage • 12 metre range • Operation voltage 7.5 - 16V DC • Tamper protected • LED indication • Size 65(H) x 84(W) x 46(D)mm • Col our beige • Relay output • 3 month guarantee Cat. LA-5017 ONLY $69.95 $30 LESS THAN ANY PIR WE KNOW OF $19.95 ONLY $39.95 PCB TERMINAL STRIP BARGAIN Another surplus stock buy. These are high quality black thermoplastic PCB terminal strip. As used by the alarm industry. Available in 4 way and 10 way. are supplied unassembled - i.e. you have to screw the screws in. Normal Price SPECIAL 1O+ 100+ Cat. HM-3204 4 way $2.50 $1.50 $1.30 Cat. HM-3206 $1.50 10way $4.95 $2.00 $1.80 BELOW WHOLESALE PRICE /, \ \.,, I '\--,\-,,) VIDEO DUBBING LEAD KIT Record from virtually any VCR to another. Normally $25.95 APRIL SPECIAL $17.95 SAVE $8.00 Cat. AV-6538 Wireless Receiver/Transmitter Consists of receiver module and 2 key fob transmitters. Press the button on the transmitter and one of the 2 output wires on the receiver will go momentarily high with respect to-1 ZV. This will control Cat. LR-8830 (see opposite) but can also be used to turn car alarms on/off, for example. Supplied with wiring instructions. Cat. LR-8820 $99.50 "" & ,_,... ..:_ 4 Door Car Power Door Lock Kit If you own a 4 door car and want the convenience of power door locking, this is the kit for you. It consists of 2 master solenoids and 2 remote solenoids. (Masters for the front doors, so opening either will unlock the other 3 doors. Full wiring harness to connect all 4 solenoids tthe doors o even the biggest cars, all hardware. Also included is the controller relay circuit (Cat. LA-8835 $26.95) which will also adapt to our remote controller (Cat. LA-8820 $99.50) so the system can be remote controlled. Cat. LA-8830 Miniature Mic Insert Brand new omnidirectional mini mic insert.Ideal for all those miniature circuits. Only 6m diameter. For specifications on this superb mic insert see THE JAYCAA 1989 CATALOGUE CAT. AM-4005 ONLY $2.20 10+ $1.90 ea Ultrasonic Transducers for Vehicles As used in many professional car burglar alarms. Consists of a separate transmitter and receiver which are covered a rubber boot with metal clip for easy mounting. Supplied with 2 metres of shielded cable. 12mm diameter, 40kHz frequency. Cat. AU-3855 $19.95 pair $159.50 OPEN AN ACCOUNT WITH JAYCAR Jaycar is now accepting account applications from all established companies who can ex hibit good trade references. For application details see our store managers or phone (02) 747 2022 WHITE CONE MIDRANGE Our most popular midrange. Large sealed back with extra clear crisp midrange. 110mm, BO watts rms power handling, 95d8 sensitivity, 10oz magnet, · frequency response 31Hz - 7kHz, resonant frequency 310Hz. Cat. CM-2080 Uses dual diversity autoswitching receivers for long range noise free pure fidelity reproduction. Dynamic range exceeds lOOdB. Superb microphone reprod uction compares with Shure, etc . Unique microphone design completely elimi nates 'dangling' antenna. The operating range is a minimum of 50 metres and often this can be extended to 200 metres or more in normal ci rcumstances. Several frequencies are available to alleviate cross interference when two or more systems are used in proximity. One frequency will only be stocked of each model. If you are purchasing two uni ts we can arrange 2 different frequencies. See our brand new 1989 catalogue for full specifications. ONLY $22.50 DUAL DIVERSITY RECEVER Cat DT-5050 8 CHANNEL AUDIO MIXER KIT ENTERTAIN MENT MIC Cat DT-5055 Ref: EA April/May 1983 Cat. KJ-6504 $595 LAVALIER MIC Cat DT-5060 Pictured with optional desk console Full specs in our 1989 cata logue Ref: Silicon Ch ip Feb 1988 About ffVery fea ture you could ever want in a car alarm. See our 1989 catalogue for full details. Extras not included in kit: Back-up battery Cat. SB-2490 $22.50 Piezo siren Cat. LA-5255 $1 7.95 12 volt siren Cat. LA-5700 $25.50 Cat. KC-5021 Fully built and tested with separate bass, treble, balance and volume controls . This superb amp has less than 0.1% distortion. There are inputs for microphone, phone and auxil iary (l ine) and all power supply components are on board. Just connect transformer, speakers and a signal and away you ge l $79.50 REMOTE CONTROL Cat. AA-0300 (Full Kit) Ret: ~111con Chip March 1988 Full form version. Kit includes all components exceot box for receiver, piezo siren and piezo transducer and battery for transmitter. These items are avail able separately: Transducer Cat. AB-3440 $2.75 Piezo Cat. LA-3255 $17.95 Battery (pkt 2) Cat. SB-2420 $3.75 Cat. KC-5034 NATIONAL LINEAR APPUCATIONS If you haven't got our brand new bumper 148 page catalogue yet (it was FREE in March issues of Electronics Australia and Silicon Chip) don't worry. It's still only $1 and contains about 4000 different products. Call into four stores, or send $2 to PO Box 185 Concord 2137 and we'll send you one. $49.95 EPROM Eraser 'SCREECHER' CAR ALARM KIT Scare the pants off would be thieves! This car alarm is fitted under the dash of the car. When a thief breaks in (after entry delay) an unbelievably loud shrill sound goes off - INSIDE THE CARmaking it too unbearable to proceed with stealing the car. The alarm has a dash lamp flasher, exit and entry delays, a 3 second soft alarm to remi nd you to turn it off. and automatic resetting The Jaycar kit includes the dir · 116d8 screecher, d components. Cat. KA-1675 SALVAGE SOME CASH Turn your surp lus stock into ca sh. Jaycar will purchase your surplus stocks of components and equipment. Will erase up to 9 x 24 pin devices in 40 minutes. Less for less chips. 240V operati on Cat. XE-4950 $99.50 Replacement tube Cat. XE-4961 $19.95 $34.95 CALL GARY JOHNSTON OR BRUCE ROUTLEY (02) 747 2022 0'1"5 Pf . _ M~~~,r1_. Cat. BN-4oo5 Almost impossible-to-get. But we have a small quantity. $79.50 BRAND NEW CATALOGUE $69.95 Transformer to suit Cat. MM-2010 $24.95 HEAD OFFICE MAIL ORDERS 137 POST & PACKING 9 0 8 !_i_:i_!_i_~~-i_~3_%_(:_~-~-:c_:4_~c_:_:i_6_: _ _ _ _ _~_t_R:_{_:~_~-~-~-~c_1i_i_:_io_:_:~_:8_:___ll_l_Rs_1o_o_l_!i_~_:_ i_J_l_~o___, VISA MAIL ORDER VIA YOUR 'Z:r ROAD FREIGHT ANYWHERE IN AUSTRALIA $13.50 SYDNEY - CITY 111 York St. (02) 267 1614 · GORE HILL 188 Pacific Hwy (Cnr. Bellevue Ave) (02) 439 4799 • Mon-Fri 9 • 5.30 Sat 9 - 4pm PARR AMA TTA 355 Church St (Cnr. Victoria Rd) (02) 683 3377 BURANDA QLD 144 Logan Rd (07) 393 0777 · Mon-Fri 9 • 5.30 Thurs 8.30 • Sat 9 • 12 Mon-Fri 8.30 - 5.30 Thurs 8.30 pm• Sat 9 • 12 Mon-Fri 9 . 5.30 Thurs 8.30 pm · Sa t 9 · 4pm ~ rd. 1 CONCORD 115 Parrama tta Rd (02) 745 3077 • Mon-Fri 8.30 - 5. 30 - Sat 8 30 • 12 MELBOURN E-CITY Shop 2, 45 A'Beckett St City (03) 663 2030 HURSTVILLE 121 Forest Rd (02) 570 7000 · Mon-Fri 9. 5.30 Thurs 8.30 pm• Sat 9 · 12 SPRINGVALE VIC Mon-Fri 9 • 5.30 Fri 8.30 • Sat 9 - 12 887-889 Springvale Road Mulgrave (03) 547 1022 Nr Cnr. Oandenong Road Mon-f ri 9 - 5.30 f ri 8.30 • Sat 9 · 2 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. r---..----➔----------------4~-----+9V .047 VR3a 100k VR4a 100k KEYBOARD ~ ii5 LEFT 10k .0022 LEFT SOURCE .,. .0022 +9V 10 ~ ..,-----,i - .,. VR3b 100k VR4b 100k +9V RIGHT t"O""'-UT_ _ _ _--0+9V TO 470 470 + 16VW+ + 25VWJ ·'~ KEYBOARD .,. .,. Keyboard sound improver Do you own one of those Casio or Yamaha keyboards with the small 5cm speakers? If you're tired of the tinny sound from these instruments, this keyboard sound improver will allow you to add more "oomph" by varying the amount of bass and treble from the keyboard output. It also connects to the line inputs of your stereo amplifier and lets you mix the keyboard output with a stereo music source. So if you want to get in sor:p.e practice, you can take the lead with your favourite piece of music. The keyboard output is first fed to a feedback tone control circuit based on VR1, VRZ and IC1 (TL071). From there, the signal is passed to inverting op amp stages IC2a and IC2b. Stereo potentiometer VR3 varies the gain of these stages between O and 10 times and thus controls the keyboard volume relative to the music source. The outputs of IC2a and IC2b are mixed with the stereo music source via 10k0 mixing resistors and then Help! Save Us From Circuit Burnout! We know we're brilliant. You 've said so yourselves. But we know that there are lots of ingenious circuits lanquishing out there in readers' brain cells. So bung 'em into us and we'll publish them in their full glory. You'll not only make some money but you'll also save us from the dreadful "circuit burnout" syndrome which happens to anyone who has to generate too many circuit ideas in too short a time. We'll pay up to $50 for a really good circuit. So transfer your circuit to paper and send it SILICON CHIP, PO Box 139, Collaroy Beach, NSW 2097 . 80 SILICO N CHIP applied to op amp stages IC2c and IC2d. Stereo potentiometer VR4 varies the gain of these op amps and so acts as the ma ster volume control by varying the signal level fed to the amplifier. Note that a mono signal [ie, from the keyboard) is mixed with a stereo signal at the outputs of IC2a and IC2b. The result of this is that the stereo signal remains normal while the mono signal sounds as if it is in the middle of the two channels. Power for the circuit and for the keyboard is derived via a 7805 3-terminal regulator. By using the resistor values shown, the regulator will deliver a + 9V rail. If your keyboard requires some other working voltage, it's simply a matter of altering the resistor values around the regulator. Note that it may be necessary to fit a small hea tsink to the 7805, depending on the current consumption of the keyboarci. Darren Yates, Frenchs Forest, NSW. ($30) Keypad alarm for car security Another alarm? Just when you thought you'd seen the end of car alarms, here's one that offers some novel features. It features keypad entry, a piezo siren and a relay cutout for the ignition or electric fuel pump. Some very expensive commercial alarms feature keypad entry, so just seeing a keypad will frighten off most joyriders. If that doesn't do the job, the alarm and relay cutout will stop all but the best thieves. Two !Cs and two transistors are used in the circuit. !Cl is an LS7225 keyless lock and sequence detector chip. This IC has inputs to accommodate a 4-bit code sequence (pins 11, 12, 13 and 14). Pin 10 is the unselected key input. If this pin is taken high by one of the unselected keys on the keypad, the opening sequence is reset and pin 5 goes high. The circuit is activated when power is applied via the ignition switch. It must then be deactivated within a certain period of time by pressing the correct sequence of keys or the alarm will sound. To deactivate the alarm, Sl (on the keypad) must first be pressed to charge the O.lµF capacitor. This holds pin 11 high for about 10 seconds, during which time S2 , S3 and S4 must be pressed in order. If the correct sequence is pressed inside the 10-second period, pin 7 goes low and turns off the red LED Relay output for Door Minder If you want to use the Door Minder circuit (SILICON CHIP, February 1988) to switch a relay instead of sounding a chime, this simple circuit modification will do the trick. By modifying the circuit as shown, you could use the Door Minder as a sensor in a burglar alarm installation. All you have to do is delete IC2 (the SAB0602 chime IC) and substitute a transistor-switched relay circuit at the output of ICl b. Now when the output of !Cl b swings high in response to a , - - - - - - - - - - - - - - - - - - - - - - - - - - - - - + 1 2 V VIA IGNITION SWITCH 6 9 Q2 BC337 100k ~ 5D R 0 1 IC2 CK 4013 s IC1 PIEZO HORN 7 100k S7225 "' -:- -:- ------.~v TO IGNITION COIL while pin 8 goes high and turns on Ql. Ql in turn drives the relay (RLYlJ and turns on LED 1 (green) to indicate that the alarm is off. The contacts of RLYl are wired in series with the ignition coil. This means that the car can only be started when the relay is on and the contacts are closed. If a key is pressed out of sequence or the time limit expires, pins 7 and 5 of !Cl both switch high. This turns on LED 2 (red) and clocks IC2 which is a 4013 flipflop. IC2's Q output now switches high and turns on Q2 and the piezo siren. The siren then remains on until the correct key sequence is entered on the keypad. When the correct sequence is entered, pin 9 of !Cl momentarily switches high and resets the flipflop (IC2). This sets the Q output (pin 1) low again and so Q2 and the piezo siren turn off. The LS7225 IC is available from Radiospares Components (phone 02 669 3666) for about $10 (Cat. 304-554). The kepad used in the prototype was obtained from Koloona Industries, 168 Belmore South Rd, Riverwood 2 210 (phone 02 533 2588). Darryl Lewis, Busby, NSW. ($30) -~--+--+---------------+sv , 300k· I RELAY '----v--- c: 180k door opening, Ql turns on and switches on the relay. Ql and the relay then turn off as soon as the output of ICl b swings low again. Note that the output of IClb drives the base of Ql via diodes D3 and D4. This is necessary because when the output of ICl b is low, it sits at about + 1.5V and this would not normally be low enough to turn Ql off. D3 and D4 overcome this problem since they reduce the voltage applied to Ql 's base by about 1.3V. D5 protects Ql from spikes when the relay switches off. A PHIL 1989 81 y ,:"'1. AN AMTRAK TRAIN PULLED by a high-speed electric locomotive of Swedish design at Stamford, Connecticut, USA. Note the complex triangular structure of the high voltage catenary wire, necessary to hold it very rigid for high speed operation. The simpler catenaries are for lower speed freight trains. < THE EVOLUTION OF ELECTRIC RAILWAYS Amtrak is the American government-sponsored rail passenger system which provides service between many large cities. It does not own lots of track but it runs America's largest fleet of passenger rolling stock. By BRYAN MAHER With the advent of the jet airliner and the creation of America's large expressway network after World War II, US rail passenger services fell into rapid decline. Many small and large railroad companies went bankrupt and ceased operations or were absorbed by larger companies. This eventually culminated in severe financial difficulties for two of the biggest railroad companies, the Pennsylvania Railroad and the New York Central. Ultimately, the US Government recognised that unless they took immediate action there would soon be no viable passenger services in the whole country. Furthermore, national security was a consideration, in the event of any further large scale wartime emergency. So it seemed essential to actively maintain passenger services, even though such an enterprise would be hard put to avoid massive financial losses in plant and running expenses. Therefore, in 1970 the US Con- PT.18: THE STORY OF AMfRAK PASSENGER SERVICES 82 SILICON CHIP ALTHOUGH IT ONLY HAS FOUR AXLES, this Amtrak loco delivers 5700 horsepower to the rails. Of Swedish design, it is designed to run at speeds up to 200km/h but is much smaller than typical American locomotives. Note the bank of resistors on top of the roof for dynamic braking. gress passed an Act creating the National Rail Passenger Corporation, to be called "Amtrak". This Act relieved US railroad companies of the obligation to run their moneylosing passenger services and in return Amtrak acquired all passenger rolling stock and equipment. Most railroads accepted the Government's offer although a few declined. The service would have to provide fast and efficient trains, with little of the opulence that was expected in the heyday of steam. From those unsteady beginnings in the early 1970s, Amtrak's services have greatly increased so that the future of passenger services in America now seems much more certain. High speeds Amtrak's express and passenger trains in America today clock up some fast speeds though they still have yet to match the high speed running of the Chicago to Los Angeles Sante Fe "Chief" crack express, or the "Hiawatha" on the Milwaukee Railroad in the 1930s. Whereas the "Hiawatha" did the 680km run between Chicago and Minneapolis in 6 hours 30 minutes, Amtrak's time is now 8 hours 45 minutes. Amtrak achieves its best speeds on the North East Corridor, that heavily used right-of-way between Washington, New York and Boston. This busy track section was purchased by Amtrak from Conrail (which had previously absorbed the Pennsy Railroad) in 1975. Amtrak now rent back to Conrail the right to run its trains on the North East Corridor for $53 million per annum. Much of the North East Corridor is electrified by llkV 25Hz single phase AC. This electrification is a legacy of past days when the now failed Pennsy Railroad ran the GGl high speed 12-motor electric locomotives. Initially Amtrak owned no locomotives, so it leased locos from the private railroad companies to haul their second-hand carriages. Gradually this carriage situation was improved by either completely refurbishing rolling stock or by the purchase of brand new "Amfleet" cars as shown in our photographs. The locomotive situation was harder to solve. The cost of leasing locomotives is high but the cost of wholesale purchase of new locos for Amtrak was astronomical. However, the brave decision to authorise such expenditure was taken and by 1980 370 brand new locomotives were hauling Amtrak trains. As well as new locomotives for the electrified section of the North East Corridor, advanced diesel electric locomotives were purchased for Amtrak trains in other areas in the country, served by 20 long distance "name" trains. The South West Limited, replacing the Super APRIL 1989 83 AMTRAK'S DOUBLE-DECK SUPERLINER coaches set a new standard for luxurious rail travel. Of all stainless steel construction, the coaches are 25.9 metres long, 4.9 metres high, 3.1 metres wide and weigh 71.2 tonnes. ' controlled with six traction motors. An on-board 1 lkVAC transformer stepped the voltage down for the thyristor controller and traction motors. These AEM6 class locomotives, numbered in the 950 series, were long and impressive in appearance but were disappointing in service. Their American designed suspension systems were unsatisfactory at the high speeds sought, prompting Amtrak to look overseas for alternatives. The success of the Swedish railway· (SJ) in running high speed Rc4-class Ho-Bo electric locomotives on their 15kV 16.6Hz single phase AC lines inspired Amtrak to lease one for trial. Thev also tried one CC21000-class French electric locomotive. The French locomotive proved to have unsuitable suspension for American conditions but the Swedish Rc4 showed the Americans how it should be done. Accordingly a deal was made with the Swedish company Allmanna Svenska Aktiebogalat (ASEA) whereby 67 electric locomotives were built in America to the Swedish ASEA design. General Motors Electro Motive Division (EMD) secured the contract and they sublet the assembly of the locomotives to the Budd company. ASEA supplied most of the electrical equipment, traction motors and thyristor controls. The AEM-7 class AMTRAK'S SUPERLINER LOUNGE/CAFE car has windows which run right up into the roof for dramatic views when passing through the Rockies. Chier of past days, does one of the longest runs, from Chicago to Los Angeles. vices exclusively, freight being relegated to adjacent parallel tracks. Shared tracks The AEM6 class This practice of one railroad running locomotives and rolling stock over another railroad's tracks is well known in the USA (and is also practised to some extent in Australia). By this means,· Amtrak operates over 41,600 kilometres of track. In addition, on the North East Corridor, Amtrak has some tracks dedicated to fast passenger ser- To fully utilise the available high speed tracks on the electrified section, Amtrak pur,chased a consignment of 176-tonne 3.BMW electric locos during 1974. These were designated as class AEM6 and rated at 137km/hour. The new locos were wired for the 1lkV AC 25Hz single phase overhead conductor and were thyristor 84 SILICON CHIP These American built locomotives were named the AEM-7 class and were numbered from 901 upwards. The AEM-7 locos are an exceptional design. Though they weigh only 91.3 tonnes, their four traction motors develop a total of 4.25MW (5700 hp). Amtrak employees have given them the nickname ''Mighty Mouse" because they are so powerful. The springing and bogie suspension design performs admirably at high speed on the electric sections of the dedicated high speed passenger tracks on the North East Corridor. Triple coil compression springs provide the primary suspension, maintaining excellent balance of wheel power and f ffl , I ~ HAIL, RAIN, SLEET AND SNOW: Amtrak trains have to cope with very cold weather as this winter shot shows. Note how the snow is pulled up into the turbulence of the train's slipstream. loading weight, and preventing load transfer from axle to axle when running over track irregularities at high speeds. If not prevented such weight-transfer could be a cause of driving wheel slip with consequent loss of driving power. Electrically the AEM-7 is quite sophisticated, running on the existing overhead conductor supply of 1 lkV AC at 25Hz. 25 or 60Hz? However, looking to the planned extension of electrification into the future, should the low-frequency system be perpetuated or should future locos run directly from a higher voltage 60Hz supply? Originally, in the 1930s, rotary converters were used to generate the 1 lkV 25Hz supply from 60Hz mains or 25Hz AC was produced directly by lower speed steam-turbine alternators. Modern trackside substations simply use transformers and banks of thyristors to convert from the 3-phase 60Hz national power grid supply to 25Hz single phase output. Either a complex version of the thyristor cycloconverter configuration is used or silicon rectifiers convert the 3-phase incoming supply to DC which then drives pulsed thyristor bridges to generate the single phase 25Hz AC output for the overhead contact wire. The second method is less efficient than the first and care must be taken with the design of either method to minimise harmonic content in the 25Hz output and also the feedback of harmonics into the national grid system. Such harmonic currents can cause havoc to radio and telephone communications, and to railway signalling systems. With these questions in mind, Amtrak have had the AEM-7 dieselelectric locomotive designed so that its on-board transformer will accept either 1 lkV AC at 25Hz, 12.5kVAC 25Hz, 12.5kVAC 60Hz or 25kV AC 60Hz. The thyristor bridges and controlling pulse generators are also designed to accept either frequency. In this way, the AEM-7 locomotive could run on the 25kV 60Hz AC single phase overhead contact wire systems that are expected to one day radiate over the whole of the USA. When the world's oil supplies do finally give up the ghost, or oil prices itself out of the fuel market, railway electrification driven by hydroelectric and coal burning 60Hz power stations must surely prevail in the USA and elsewhere. Traction motors At high speeds and/or on any track irregularities, a problem in all electrically driven or diesel electric vehicles is the torque-shock transferred from the running wheel gear to the motor armature. Such rotary shock loading on the motor pinion causes excessive wear on the gear teeth, as the motor pinion is directly coupled to the heavy armature. These transmitted shocks also shorten the life of the armature winding slot insulation. Over the years, various locomotive designers have considered this problem and one effective method was used by the famous APRIL 1989 85 AN AMTRAK "SHORTIE" PULLED BY a diesel electric loco skirts the Windsor Locks in Connecticut. Raymond Loewy and others on the Pennsylvania Railroad with the GG-1 back in 1934: hollow shafts. Accordingly, the AEM-7's traction motor armatures have hollow shafts. Within this hollow shaft lies a second shaft on which is mounted the driving gear pinion. The inner shaft is fixed to the outer shaft (which carries the armature) only at the other end (ie, the commutator end), thus allowing torsion twisting spring action to occur while effectively isolating the armature itself from rotary shock loading. Motor control The four traction motors of the AEM-7 are each rated at 1.063MW. This power rating of greater than lMW (1340 horsepower) per axle is very high. Indeed, it does not seem long since the world marvelled at the Swiss Federal Railways when they introduced a locomotive which boasted 1000 horsepower per axle! The reason why so much power can be delivered reliably to the four axles is the complex thyristor control system. The AC supply from the on-board transformer is rectified and varied as required by phase 86 SILICON CHIP controlled thyristor bridges to provide DC to the traction motors. Additional thyristor bridges and associated gating pulse generators separately control the power to armature and field coils. In this way the motors can be made to exhibit variable characteristics, from a series characteristic producing exceptionally high starting torque (hence high tractive effort) at starting, to the weak field condition more like a shunt DC motor, for high speed running. Dynamic braking is by the conventional method whereby the traction motors are connected as generators, with their field current still supplied from the thyristor control system. The high currents generated under braking are dissipated in large fan-cooled resistor banks. Automatically blended loco air brakes and train air brakes take over at very low speeds. Full air brakes are always available for emergency stops. High speed contact wire For high speed electric running, the overhead conductor and supportive catenary suspension wiring must be well designed and installed, and properly tensioned. Ideally, the overhead contact wire should always be at a constant height above the track but as this is not attainable, the variation (ie, sag) in height between supports should be minimised. This is to enable the pantograph mounted atop the locomotive to maintain contact with the overhead wire at all speeds. For very high speeds (up to 193 km/h), the next design step is to install a lightweight pantograph assembly so that its upward spring system can quickly respond to changes in contact wire height. A lightweight pantograph design is allowed because the contact wire current is relatively small (385 amps maximum) compared with over 3000 amps which would be demanded by any 1500V DC locomotive. The Amtrak AEM-7 locomotive is equipped with two pantographs, though it is usual to run with only one raised. One of the photos in this article shows an Amtrak AEM-7 locomotive running through Stamford, Connecticut. You will notice that causes travel sickness in passengers. Modern methods of laser controlled survey and alignment produce excellent smooth track. Signalling systems also must be upgraded for such fast running. Today's Amtrak system gives drivers three kilometres or more warning of any stop signal ahead. Amfleet THREE OF AMTRAK'S FP40H DIESEL electric locos await their next task. Amtrak purchased 370 of these locos to pull its passenger trains all over the non-electrified routes of America. As with most American locos, it is fitted with an integral plough to enable it to cope with snow on the tracks. AMTRAK'S SINGLE DECK CARS are used on shorter routes where sleeping accommodation is not necessary. the overhead catenary suspension system is complex, consisting of four longitudinal cables, including the lower contact wire. As well as providing additional current carrying capacity (and less line voltage drop), the overhead construction aims to minimise vertical and sideways bounce of the contact wire as a train runs beneath it. The problem of bounce is put into perspective when you consider that, at 200km/h, a train runs at 56 metres per second or one metre every 18 milliseconds. So any sag in the overhead contact wire is lifted by the pantograph in about 25 milliseconds, an action which may give rise to excessive bounce unless closely controlled. Naturally for such high speeds the track alignment must be exceptionally good, both vertically and hoizontally. Excessive sideways misalignment, as well as giving passengers rough riding conditions, causes rail and flange wear. Too much vertical misalignment also Amtrak is progressively introducing new express passenger cars to provide their patrons with increased comfort and enjoyable riding on long distance trains. Running over great distances, trains on such runs as Chicago-Los Angeles provide luxury service with their "superliners". Built by Pullman Standard at their Hammond plant in Indiana, the day coaches are of stainless steel, double deck, 26 metres long, 3.13m wide and 4.92m high. These large and impressive eight wheel vehicles weigh 71.2 tonnes empty. The lounge-cafe car shown in one of the photos has similar dimensions. It allows passengers to eat on the lower or upper deck, or to enjoy the magnificent scenery when passing through the Rocky Mountains. The longitudinal lounge seats on the upper deck combine with broad side and roof windows to give an unimpeded view. Amtrak also provides a double deck restaurant car with 72 seat saloon and waiter service on the upper deck. The air-conditioned all electric kitchen is on the lower deck. Sleeping accommodation is available in three classes of berth: an economy unit, a family bedroom suite and a deluxe bedroom suite with swivel chair, two beds, private toilet and washroom facilities. Diesel electric Diesel electric locomotives are used outside the North East Corridor electrified regions . The backbone of the fleet is the General Motors EMD F40PH, as shown in our photos. This locomotive is 17.28 metres long, 4.75 metres high and 3.29 metres wide. It weighs 118 tonnes and carries 7600 litres of diesel fuel and 3.24 tonnes of cooling APRIL 1989 87 AN AMFLEET-EQUIPPED TRAIN, pulled by an AEM-7 locomotive, leaves Washington DC for its high-speed dash to New York City. The AEM-7 locomotives, based on an ASEA design, were built by the Electro-Motive division of General Motors at LaGrange, Illinois. water, lubricating oil and sand .. As well as pulling the train. these 2.24MW (3000 hp) Bo-Bo locomotives are required to provide as much as 800kW of electrical power loading for train heating, air conditioning, lighting and the kitchens. Suen enormous electrical train loading is unknown in Australia as our trains do not have to climb through snow drifts and ice in mountainous regions. These locos are capable of negotiating curves as sharp as 43-metre radius for 42° turning [engine alone) or 97-metre radius for 18° turning when hauling trains. Multiple units The F40PH locos may be operated multiple-unit by hooking up eight electrical control cables. Additional air hoses join all loco main air reservoirs together when in multiple-unit. This facility, never provided in steam locomotives, gives extra air flow rate for hard braking. Wheel slip detection and control 88 SILICON CHIP is provided under acceleration and wheel slide under braking is prevented by using separate dynamic braking resistors for each traction motor, allowing separate control. Alternator The diesel engine direct drives the 16-pole main alternator to generate 3-phase 200VAC which is rectified to give 600V DC for the four traction motors. The alternator fields are supplied through separate silicon rectifiers. Standby electrical power is provided by a 32-cell 64V DC 420Ah battery mounted under the frame, each battery cell having 25 plates. The battery is charged by an auxiliary 24kW generator driven by the diesel engine. The 64V DC supply powers all motor, engine and dynamic brake control circuits, the cab and headlights. Also the battery is used to drive two 32V starter motors connected in series to start the diesel engine. The driver alertness . control is the "Train Sentry 11 Alertor", manufactured by Pulse Electronics Inc. This is activated by remote radio signal and if the driver .does not respond, it will shut down the diesel engine to idle, apply brakes, blow the air horn and wait for manual reset. An event recorder, also made by Pulse Electronics Inc, records nine principal functions: time, distance, speed, motor current, throttle position, brake condition, horn operation, cab signal acknowledgment by the driver and action of multiple units. So in the last ten years or so, Amtrak has gone a long way to upgrade and expand passenger services in the USA. Though it has its critics, Amtrak carries over 20 million passengers per year and operates 500 rail stations. However, the system still loses money. Only time will tell whether the faith Congress has in its future will be justified. ic Acknowledgement: our thanks to Amtrak , USA for their assistance in preparing this article and for all the photographs . I PRODUCT SHOWCASE I attractively housed in high impact polystyrene cases and all have long shelf life and a wide operating temperature range. For further information , contact Power-Sonic Australia Pty Ltd, 5/60 Fairford Road, Padstow NSW 2211. Phone (02) 790 4441. Economy case from Dauner Electronics \Hll\l\HHl!l!\HlHHlll!il!!!!U Rechargeable batteries from Power-Sonic While you can buy rechargeable sealed lead acid batteries from parts suppliers, the selection is strictly limited. A much wider selection of rechargeable batteries, from the large to the quite small, is available from Power-Sonic Australia Pty Ltd. Just two of the wide selection are illustrated above. The smaller battery, type PS-605 , is a 6-volt unit with a capacity of 0.5 amp-hours, at a 20-hour rate. It has lugs for push- on connectors and has a maximum discharge current of 5 amps. It measures just 57mm long, 50mm high and 14mm thick and weighs only 90 grams . It retails for around $12 including sales tax. The larger battery, type PS-1207, is a 12-volt unit with a capacity of 0.7 amp-hours at the 20 hour rate. It comes with a standard Mate-NLock connector, as used in many radio controlled cars, and has a maximum discharge current of 7 amps. It measures 96mm long, 61.5mm high and 25mm thick. It retails for around $20 including sales tax. The whole range of batteries is 1m1m1mu1m111nttH\ttii\lli This very well made steel and aluminium case measures 375mm wide, 105mm high and 197mm deep and could be just the ticket for a power supply, amplifier or any number of electronic projects. The big problem is the price. It is just too low to be believable. Yep, just $4.50. It is available only in limited numbers from Dauner Electronics, 51 Georges Crescent , Georges Hall, NSW 2198. Phone (02) 724 6982 . Ultrasonic cleaning bath for small items Low cost phone answering machine The Callmate 1700 is a single cassette telephone answering machine capable of handling calls up to 2 minutes long. When placed in auto answer mode the call is answered after the first ring, then an electronically recorded message up to 12 seconds in length is played back to the caller. The Callmate 1700 has voice operated relay circuitry so that gaps and delays between recorded messages are avoided. The recordin g apparatus comes complete with a 60 minute leaderless cassette, AC power pack, Telecom line socket and a 9V battery to maintain the memory if power fails. The Callmate 1700 is available from Da vid Reid Electronics at $169.00. This small ultrasonic clea ning bath is ideal for cleaning drafting pens, small tools. carbiirettor parts. glasses, printed circuit boa rds. connectors, switches a nd so on. It is basically a small stainless steel bath with a piezolectric transducer atta ched to the bottom and driven at 40kHz. It a gita tes the A l'll/L 1989 89 water or solvent in the bath and very effectively cleans any small item. One warning though: we would not attempt to clean a watch in it, whether it is waterproof or not. Leave that to the watchmaker; if he damages the watch, he pays. For other items though, it works like a treat. The unit is mains powered and has a built-in 3-minute timer so that you can set it to work and not worry about turning it off. Price is $199.00 from Altronics, 17 4 Roe Street, Perth, WA 6000. Phone (09) 328 1599. Cordless remote headphone Enjoy your favourite movie or music in complete privacy without being tied to one spot. The Arkan Videophone system is a cordless infrared system that will accept any mono audio source and transmit it to your headphone receiver up to 15m away. The received sound will be reproduced in mono or in simulated stereo. .SONI&' INTERNAL SALES Due to a promotion, a position has become vacant for a friendly, outgoing person with a pleasant phone manner to handle internal sales. We envisage that the- successful applicant will have had previous sales experience in electrical/electronics components . Clerical experience with computer entry would be highly regarded . This position in the world of high-tech batteries may suit a mature person, however all applicants will be treated on their merits and in complete confidence. Please contact Karen or Ian on : 790 4444 in the first instance. 90 SILICON CHIP The transmitter is powered by a 240V AC plugpack. The audio input signal is modulated onto an infrared source which is picked up by the receiver built into the headphones. The range of the system is essentially line-of-sight so other units can be used in adjoining rooms without interference. The Videophone package comes complete with headphone receiver, transmitter unit, plug adaptors and AC plugpack. A 9V battery is required for the receiver. The complete package sells for $99 and is available from David Reid Electronics, 127 York Street, Sydney. Phone (02) 267 1385. Crossovers from Nelson Components Those who want to build the Minstrel 2-way loudspeakers described in the February 1989 issue of SILICON CHIP will be interested to know that fully built and tested crossover networks with low loss components are available at $40 each, including tax. Nelson Components can make any crossover network to order and can supply low loss inductors for crossovers. For furth13r information, contact the company at 18/59 Moxon Road, Punchbowl, NSW 2196. Phone (02) 709 5296. 150MHz RF signal generator At one time or another every workshop needs an RF signal source capable of 100mV or so and up to 30MHz or more. This Lodestar SG-4160B goes a lot further than that, and covers the range from 100kHz up to 150MHz in six ranges and with useable harmonic output up to 450MHz. Actually, we are always a little wary when we see that a signal generator has useable harmonic output because it implies that the waveform is distorted; ie, it has plenty of "harmonic distortion". However, we had a look at the output waveform from the generator over the range up to 50MHz and can state that it is quite clean. It is also notably flat in output and the dial calibration is very good - within a pointer's width or less than ± 3% at any freqµency. Other features include internal amplitude modulation to 30% at lkHz, a socket for external modulation and a crystal socket for crystal locked operation. In short, the Lodestar SG-4160B is a neat little unit, nicely finished and keenly priced at $225.00. It is available from Altronics, 17 4 Roe Street, Perth; WA 6000. Large digit multimeter from DSE This sleek looking digital multimeter has a particularly large liquid crystal display with digits which are 21mm high. This is very large compared to most digital multimeters and should suit those who find ordinary meters hard to read. D.DAUNER ELECTRONIC COMPONENTS WE STOCK A WIDE RANGE OF ELECTRONIC PARTS • for Development • Repair • Radio Amateur • Industrial Electronic • Analog and Digital WHILE STOCKS LAST CFE 455 RESONATOR $2.80 ea • 7552 COAXIAL CABLE (4 SHIELDS) CG? $0.90/MTR • 50 ONLY METAL PROJECT INSTRUMENT CASES 370mm(L) x 90mm{H) x 180mm {D) $4.50 ea • It offers the full range of measurements: AC/DC volts, AC/DC amps, Ohms, Diode, Continuity and frequency counter. The unit is autoranging and has 9 pushbuttons for on/off and function selection. A data hold function is included. The unit is now available from all Dick Smith Electronics stores (Cat. Q-1524) and sells for $129. Come and see. Showroom: 51 Georges Crescent, Georges Hall, NSW 2198 (Behind Caltex Service Station In Blrdwood Road) Phone 724 6982 TRADING HOURS: Monday to Friday 9.00 a.m. to 4.00 p.m. Saturday from 9.00 a.m. to 12.00 noon. Polystyrene capacitors COK-IMUNICAT,t?NS PTY L TO YES RF SERVICE TECHNICIANS Made here in Australia? YES Several opportunities exist for RF technicians in our new service department located at Silverwater. Responsibilities include calibration and maintenance of a wide range of commercial VHF and UHF transceivers, marine equipment, cordless telephones and RF related products. Some SMD repair work is anticipated. Made Special to Type? YES Where From? Allied Capacitors Australia Allied Capacitors Australia specialises in custom made good quality, high stability polystyrene capacitors. Why design circuitry which requires additional components to achieve a specific capacitance; we can wind exactly the capacitance you need to match your design criteria within the ranges of 10pF to 1µ,F and up to 10,000VDC . Capacitors are manufactured to 0.25%, 0.5%, 1.0%, 2.0%, 2.5%, 5%, 10% and 20% and are priced according to tolerance. All capacitors are tested to 2.5 times the rated voltage . r----------l Yes, I am interested in your capacitors. Interested? Call us now on: I Please post me details of the following I ... /... VDC. / . .. VDC ... / ... VDC (02) 938 4690 OR Cut out and post this coupon Post Office Box 7 40 to I Name (Please print) _ / ... VDC . ~-~--~~--~~--.J I Address __ s_ ro_o_k_ va_ie _ ,_ N _ .s_.w _ . _2_1_00_ _ __ values: A Radiotrades or Electronics & Communications Certificate or equivalent would be an advantage, however practical experience in the industry is essential. Excellent working conditions & above average wages apply to the right applicants. This is an ideal opportunity for motivated, practical self-starters to join one of Australia's fastest growing telecommunications groups. For full details and an interview please write to: ACCESS COMMUNICATIONS GROUP RF TECHNICIANS PO BOX 231 NORTHBRIDGE, NSW 2063 APRIL 1989 91 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. Ultrasonic proximity detector I made the Ultrasonic Proximity Detector described in the January 1989 issue. Because it did not work, I compared the circuit and parts layout diagrams and noticed that D1 was shown the wrong way around on the circuit board. The circuit is now almost working but I am unable to properly control it with the trimpots. The beep rate stays the same as I come closer, then at a close distance I get a continuous tone. (A. B., Box Hill North, Vic). • Our apologies for showing D1 the wrong way around on the parts layout diagram (Fig.3). Errata on this appeared in our March 1989 issue. We suspect that you have used an ordinary 555 timer for IC4 instead of the specified TLC555CP Variations on the Mains Muzzler I intend to construct the Mains Muzzler described in the January 1989 edition of SILICON CHIP. There are, however, a couple of points which I hope to change to reduce the cost of the unit without affecting its performance. Since I already have a 4-way power board extension lead for the computer and peripherals, there is no need for the sockets mounted on the case. There appears to be no attempt made in the unit to prevent the introduction of radiated noise between the filter and computer and so there would seem to be no objection to using an ABS plastic case to house the filter board. With these points in mind, a further saving in cost may be effected simply by cutting the mains flex of the 4-way board 92 SILICON CHIP CMOS version. An ordinary 555 timer will excessively load the "average signal" line and cause the symptoms you describe. Wants telephone exchange project SILICON CHIP is a great magazine. I always enjoy the Serviceman's Log and articles on the history of things electrical; eg, the electrical railways series. May I suggest an article on Telecom's Commander telephone system, describing how it works etc. Also, could you design a small automatic telephone exchange, not for connection to Telecom lines but for use in the house, garage, workshop etc, or a small factory or shop. This could be combined with some of the simple phones that are now available for around $20. With reference to " The Way I and terminating the flex directly to the in and out terminals of the filter. Of course, the flex would have to be securely clamped where it entered each end of the ABS case. If these points are valid, you may wish to publish the information for others who wish to save money. Incidentally, I notice on the front cover and the photo on page 32 of the January issue that there is a notation on the prototype indicating "1kW ma x". As no reference is made to this limitation in the text of the article, could you please verify if this applies to the published design? (W. N., Yeerongpilly, Qld). • There is no reason why you should not use a 4-way extension board and house the filter components in a separate ABS box as you propose. The design rating is 1kW, as noted on the label. See It", January 1989, page 63, was the circuit of the "Kiro-Vox" drawn as published? The filament circuit has no connection to + A. (J. M., Katoomba, NSW). • Would anyone like to write an article on Telecom's Commander system? We would certainly welcome an article on this particular subject. A small automatic telephone exchange sounds like a great idea too. We'll see what we can do. In the meantime, if any reader has a suitable circuit we would be only too happy to consider it for publication Yes, the "Kiro-Vox" circuit was drawn as published. You are perfectly correct about the nonexistent + A connection - that's just one more reason why the circuit wouldn't work as claimed. Command control for model railroads First, let me congratulate you on your magazine. I only started reading it 6 months ago but now look forward to each month's issue. Have you ever considered a "Command Control" system for model railroads. I have been using a Zero-1 setup since it first became available and would hate to go back to the old system. It's true the Zero-1 had some shortcomings but an added booster solved the lack of power and its habit of loosing memory was due in my case to: (1). an open-circuit diode across a relay in another part of the layout; and (2). a slow motion switch machine (Bemo) which needed a bypass capacitor across the motor. The big disadvantage however is that Hornby has ceased production of the Zero-1 system, leaving users out on a limb as far as loco modules a re concerned. A circuit of a clone loco module, even though larger in size, would be great. The current Problems with ignition circuit I have a problem with the High Energy Ignition described in SILICON CHIP in May 1988. It doesn't work at all. After putting the kit into a suitable location in the car, I encountered a strange problem. The power transistor was sparking from collector to earth when trying to start the car. Further examination revealed that tightening the transistor mounting screws: caused a massive drop in resistance between collector and emitter. A new mica washer and new insulating bushes seem to have fixed this problem but I wonder if any damage was done. On a multimeter diode and resistance check, no apparent difference can be seen when compared to a new Darlington transistor. I have enclosed a circuit diagram marked with the voltages obtained when the ignition is on. (G. H., Lower Templestowe, Vic). • First of all, check that the crop of commercial offerings (Kato, Fleishmann, etc) look very expensive when the cost of the modules is added up. No doubt, you have seem MODEL RAILROADER'S CTC16 command control which looks quite attractive although some parts could be hard to get here. I realise the limited appeal this type of project would have but if readers don't write, you'll never know that at least one is interested. (J. H., Camden, NSW). • Thanks for the suggestion. A command control system is a complicated project but we will consider it if other readers express sufficient interest. Parts availability would not be a problem. Remote switch for car burglar alarm I have built the Protector car burglar alarm which appeared in the February 1988 issue of SILICON power transistor (Ql) is insulated correctly from the metal case and that the mounting screws are tight. You can easily check that the transistor is isolated from the case by using a multimeter switched to a low ohms range. If the meter shows a short between Ql 's collector and case, remove the transistor and check the mounting surface. it should be perfectly smooth and free of metal swarf. Replace the mica washer . if punch through has occurred. You can now check the circuit operation. To do this, connect a + 12V supply to the + 12V rail and connect a multimeter (switched to the ZOV range) between the collector and emitter leads of QZ. QZ's operation can now be checked by using a clip lead to simulate the action of the points. When the clip lead is open circuit (ie, points open), QZ's collector voltage should be close to OV. Conversely, when the points input is shorted, QZ should turn off and its collector voltage should CHIP and would also like to install a UHF remote switch. Unfortunately, because my knowledge of electronics is very limited, I found that the one described in March 1988 was too difficult for me to build. Instead, I want to use the UHF switch sold by Oatley Electronics as I already have one of these units. I have not yet been able to connect the UHF switch because it only has one control line for on/off functions whereas your alarm has two separate lines. If you could help me with this problem, I would be grateful. - Also, I was wondering if you had any plans for a 10-band graphics equaliser. I would also like to see an inexpensive digital AM/FM stereo tuner, to complement the other audio projects that you have designed. Finally, I own an NEC stereo VCR and would like to use it to record audio signals from my hifi system. immediately rise to the supply voltage ( + 1 ZV). You might also like to check QZ's base-emitter voltage. It should be OV with the points shorted and about 0.65V with the points open circuit. If you don't get these voltages, try replacing QZ. Ql can be checked in similar manner. With + 12V applied to the circuit and wjth the ignition coil connected, you should get a reading of about 1V on its collector. Now disconnect your multimeter and short the base of Ql to ground using a clip lead. The transistor should immediately switch off and its collector voltage should briefly rise to several hundred volts. With a paper clip bent over between the HT socket and close to one of the primary terminals, you should get a hot spark. If the two transistors check out OK and you can't find anything else wrong, try replacing !Cl (MC3334P). It might have been damaged by a power supply transient during your initial troubles with Ql. Can you please advise me on how to do this? • It should be possible to connect your UHF remote switch to the Protector burglar alarm by using the outputs of the 4013 IC. The Q output (pin 13) could be used to turn the Protector alarm on, while the Q-bar output (pin 14) could be used to turn it off. To connect the two circuits together, both should be powered from the car battery which means that ground of both circuits will have the same potential. Then, pin 13 of IC3 in your UHF receiver circuit should connect to pin 4 (Sl) of the Protector's terminal block. Similarly, pin 12 of IC3 should connect to pin 5 (SZ) of the Protector's terminal block. We don't have any plans for a 10-band graphic equaliser but we are currently working on a stereo half-octave equaliser design which will have 20 bands per channel. It will all fit into a rack mounting case APRIL 1989 93 What ever happened to blue LEDs? Perhaps you could provide some information on a subject that's been bugging me for some time: what ever happened to blue LEDs? Over 10 years ago, we were repeatedly told that blue LEDs would be available soon but so far the only ones I've heard of are made by Siemens and cost over $150 each! (And there weren't any available anyway). LEDs with a red and green chip in the same package are available and by varying the current ratio of the two diodes, colours ranging from red through orange, yellow and green can be synthesised. If a blue chip could be added to this package, virtually any colour could be obtained. This could put some new life and will be capable of much finer frequency control than is possible with a 10-band design. We'd certainly like to do an inexpensive digital AM/FM tuner but it would be hard to better the performance of readily available commercial units without considerably exceeding the price. As far as recording audio-only signals on your stereo VCR is concerned, we weren't too sure whether it could be done, not having· ever bothered to try. But we gave it a whirl and it does work. Apparently the lineal speed of the tape is constant whether or not a video signal is present. However, since the effective tape speed is so slow, the sound quality is strictly low fidelity, with a fair amount of hiss when played back through a good stereo system. Presumably a Dolby VCR would be better in this respect but a hifi VCR is the real answer. The method of recording is simple. Just take a stereo signal from the tape monitor outputs on your stereo amplifier (or any other line level source such as a CD player] and feed it to the stereo RCA input 94 SILICON CHIP into the consumer electronics industry .- just imagine the sort of control panels they could come up with. I actually have a more practical use for a blue LED, though. I wanted to make a cheap substitute for a gadget called a "Grafikon" which is used for setting the colour temperature of TV monitors in video production facilities (it's a more elaborate version of the "Color-trak" fluorescent lamps used by TV servicemen). As a white reference, the Grafikon uses an inexpensive 1V incandescent lamp, which needs to be recalibrated or replaced on a regular basis, and a mains power supply. I figured I could use a combination of red, green and blue LEDs to substitute for the lamp, and this would also allow battery operation. The only snag is that no blue LEDs have been forthcoming. No- sockets on the back of your VCR. Use the remote control or front panel controls to set VCR channel input to "Aux" and then push the recording button. Playback is equally simple: connect the stereo outputs from your VCR to the Tape Monitor inputs on your amplifier and hit the Play button. Interestingly, while a standard VCR has low-fi sound quality it is better equipped to record the wide dynamic range of CDs than most hifi stereo cassette decks, simply because it has an ALC (automatic level control) circuit. Converting valves to solid state For the non-purist valve radio enthusiasts among us, how about a couple of articles on converting valve radios to solid state with minimal disturbance to the original circuit. The RF/IF valves could perhaps be replaced with high-voltage FETs and the AF stage by a high-voltage power transistor or by a small module driving the speaker via a one seems to know much about them, either. I would be interested to hear if you or any of your readers can throw any light on the subject. (K. W., Lane Cove, NSW). • Blue LEDs are listed in the current Siemens catalog with the type number LB5410-HO. We contacted Siemens in Sydney who advise that the devices are available on special order for just under the $50 mark. These LEDs are expensive and will always be so, since they a re based on silicon carbide. Suggested applications fo r blue LEDs include a calibration light source for photomultipliers, in TV camera engineering and photography, and as a radiation source in spectroscopy, biophysics and medicine. If you need further information and devices, Siemens is the source. Phone them on (02) 436 8711. capacitor (bypassing the speaker transformer). With the growing scarcity and increasing cost of radio valves I am sure there are many people who would be interested in articles along these lines. Also, there are many older people who have a great sentimental attachment to their old valve radio. These people would appreciate having it kept operational. (J. M., Cockatoo Valley, SA). • Sorry J. M., but we don't think that the idea is practical. If you want to keep an old valve radio operational, it's best to replace valves with valves. Most of the common types are still available, even if you have to scrounge them second hand. Notes & errata 120W Public Address Amplifier, December 1988: the switch contacts 1 and 2 associated with the 6.5mm jack socket (top lefthand corner of the circuit) should be shown normally open, not normally closed. The wiring diagram on page 45 of the January 1989 issue is correct. Silicon Chip Back Issues November 1987: Car Stereo in Your Home; 1 GHz Frequency Meter; Capacitance Adapter for DMMs. December 1987: 1 00W Power Amplifier Module ; Passive lnfrared Sensor, Universal Speed Control and Lamp Dimmer ; 24V to 12V DC Converter. Janua ry 1988: 4~ wtie UHF Antenna ; Qu~ inm.~ al,ver Supply ; Custom ffj O),,~ Subcarrier Adapter for 5M-'!"uriers: February 1988:· 200 Watt Stereo Power Amplifier; Deluxe Car Burglar Alarm ; End of File Indicator for Modems. March 1988: Remote Switch for Car Alarms ; Telephone Line Grabber; Endless Loop Tape Player. April 1988: Walkaround Throttle for Model Railroads; pH Meter for Swimming Pools; Slave Flash Trigger; Headphone Amplifier for CD Players. May 1988: Optical Tachometer for Aeromodellers; High Energy Ignition for Cars; Ultrasonic Car Burglar Alarm. June 1988: Stereo Control Preamplifier; Breakerless Ignition For Cars; Automatic Light Controller; Mega-Fast Nicad Battery Charger. July 1988: Fitting a Fuel Cut-Off Solenoid; Booster for TV & FM Signals; The Discolight Light Show. August 1988: Plasma Display; Remote Chime/Doorbell; High Performance AC Millivoltmeter; Getting the Most Out of Nicad Batteries. September 1988: Hands-Free Speakerphone ; Electronic Fish Bite Detector; Switchmode Charger for 1 2V Gel Batteries; Vader Voice. October 1988: Stereo FM Transmitter; High Performance FM Antenna; LedLight House Number; Matchbox Crystal Set. November 1988: 120W PA Amplifier Module; Poor Man's Plasma Display; Car Safety Light; How to Quieten the Fan in Your Computer. December 1988: 120W PA Amplifier; Diesel Sound Generator; Car Antenna/Demister Adaptor; SSS Adaptor for Shortwave Receivers. January 1989: Line Filter for Computers; Proximity Detector for Cars; Computer Sound Repeater; How to Service Car Cassette Players. February 1989: Transistor Beta Tester; Build the Minstrel 2-30 Loudspeaker System; LED Flasher for Model Railways. March 1989: LED Message Board; 32-Band Graphic Equaliser ; CD Compressor; Amateur Band FM Receiver; Map Reader for Trip Calculations BACK ISSUES ORDER FORM Please send me a back issue for: □ November 1 987 □ May 1988 □ December 1 98 7 □ June 1988 □ February 1 988 □ July 1988 □ April 1988 □ December 1988 □ October 1 988 □ November 1988 □ September 1 988 March 1989 □ □ January 1989 □ February 1 989 Enclosed is my cheque/money order for $ ______ or please debit my D Bankcard D Visa Card D MasterCard Price: $A5.00 each (includes postage). Overseas orders add $A 1.00 per issue for postage . Signature _ _ _ _ _ __ _ _ _ Card expiry date_ _; __; _ _ NZ & PNG orders are sent by air mail. Name (PLEASE PRINT) Detach and mail to: SILICON CHIP PUBLICATIONS Stree._________________________ PO BOX 139 COLLAROY BEACH Suburb/town, _ _ _ _ _ _ _ _ __ _ _ _ Postcode____ NSW 2097 □ March 1988 □ August 1988 -------------------------95~ APflII, 1989 T CEl't'I' Cash in your surplus gear. Advertise it here in Silicon Chip. Advertising rates for this page: Classified ads - $7 .00 for up to 15 words plus 40 cents for each additional word; Display ads (casual rate) - $20 per column centimetre (max. 10cm). Closing date: five weeks prior to month of sale. If you use a PO Box number, you must include your permanent address and phone number for our files. We cannot accept ads submitted without this information. To run your own classified ad, put one word on each of the lines balow and send this form with your payment to: Silicon Chip Classifieds, PO Box 139, Collaroy Beach, NSW 2097. PLEASE PRINT EACH WORD SEPARATELY IN BLOCK LETTERS 2 3 4 5 6 7 8 9 10 11 12 13 14 15 ($7.00) Name ............ ..... .. . Address .......... ......... ..... ... .. ... .... ..... ........... . ... ....... ... .... .. . Suburb/Town . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. ...... ...... ........ . Postcode Enclosed is my cneque or money order tor$ ........... ...... ...... ... ... ..... or please debit my 0 Bankcard D Visa Card O MasterCard Card No IL ----1..~_ _j__...J.._- ' - - ' - - - ' - - - '-_j__--'---'-_j___J___l_.J...__j Signature . FOR SALE BUILD YOUR OWN LED Moving Message board. $75 for a 4-character display experimenter's short form kit and $1 50 for 16 characters . Kit con- UPGRADES FOR THE TANDY 1000 20Mb hard disk plus controller card $899.00 . 40Mb hard disc plus controller card $1099.00 . RS232 plus real time clock card $89 .00 . Phone David on (047) 31 255!=! for more rli:>t~ilc:: THE BUBBLE-ETCHER Our Bubble-Etcher now has a heater. Reheat the etchant when you need it. Let the air bubbles do the stirring. The perspex tank forms a vertical slot. You see the etching proceed. Suits boards up to 1 2 x 10-inch. Ask us for a pamphlet. Sesame Electronics Pty Ltd, PO Box 452, Prahan 3181. Phone (03) 527 8807. 96 SILICON CHIP . .... Card expiry date ... ... ../ ....... / ....... . sists of PC boards, EPROM and full instructions to complete the project to a professional standard. Loaded from Centronics printer port or PC/XT keyboard. Equivalent commercial units start at around $1000 . For more info send a 39c stamp to Don McKenzie , 29 Ellesmere Crescent, Tullamarine 3043. HI-TECH STEREO AMPLIFIERS built. Reasonable prices. For full details send SAE to 36 Palmer St, Nambucca Heads, 2448 . GEIGER COUNTER HANDHELD. Detects x-rays , alpha, beta, gamma. Alert function. CPM , LCD. For brochure send SAE: 10 Devonshire St, Hawthorn, SA 5062. RADFAX 2: HI-RES RADIO tacsIm11e, Morse and RTTY program for IBM PC/XT on 360K 5.25-inch floppy plus full documentation . Need CGA, SSB HF, FSK/tone decoder. Has re-align , auto-start, view, save, print. Also " RF2HERC " same as above but suitable for Hercules card and "RF2EGA" for EGA card (640 x 350 mode). Programs are $30 each plus $3 postage. Only from Michael Delahunty, Advertising Index Access Communications ..... .. 91 Allied Capacitors .......... .. ...... 91 Altronics ...... ......... ... 66-69, 73 Arista Electronics ..... .. .... ...... 65 Avtek ... ................. ............. 21 Ballarat Electronic Supplies . . . 1 9 Chapman, L.E . ... .... .. ........ ... 45 Dauner Electronics ... .. ......... 91 David Reid Electronics ........ .. 11 Dick Smith Electronics .... . 12-1 7 Elmeasco . .. . . . . . . .. . . . . . . . . . . . . . OBC Geoff Wood Electronics .... .... 55 Goldstar ............... .............. 35 Hycal Instruments .. ... .......... . 1 9 Jaycar Electronics .. ... ..... 26-29 76-79 J.V. Tuners .. .... ... ... ... ... .. ..... 73 Philips TMI ... ....... .. ... ... .... IFC,3 Powersonic .. .. .. ... .. ....... 90,IBC RCS Radio ..... ........ ...... ... .... 65 Rod Irving Electronics .... ... .... 59 PC Boards Printed circuit boards for SILICON CHIP projects are made by: • RCS Radio Pty Ltd , 651 Forest Rd, Bexley, NSW 2207 . Phone (02) 587 3491 . • Jemal Products, 5 Forge St, Welshpool, WA 6106 . Phone (09) 350 5555. • Marday Services, PO Box 19-189, Avondale, Auckland , NZ. Phone 88 5730. 42 Villiers Street, New Farm , Old 4005. Phone (07) 358 2785. BOOKS & PLANS LOW SPEED GENERATORS for windmills, water turbines, steam engines. The definitive book: "The Homebuilt Dynamo" (1987), 182 pages , 8.5 " x 12", hardback. Generator design and construction with ceramic magnets. Complete plans, 268 photographs , step-by-step construction details. $A85.00 postpaid airmail (brochure $A5.00 refundable). Todd-Forbes Publishing, 627 West Coast Road, Oratia, Auckland. 4 REASONS TO CHOOSE POWER-SONIC BATIERIES PERFORMANCE RELIABILITY Bold claims are made by battery manufacturers old and new claiming one "breakthrough" or another. The fact is, only time will tell the true quality of a product. POWER-SONIC has been building sealed rechargeable batteries for over 20 years and its state-of-the-art design and unmatched track record for dependable performance have earned it the confidence of engineers and buyers the world over. You can rely on POWER-SONIC sealed rechargeable lead-acid and nickel-cadmium batteries in the toughest environment - be it extended power outages, high or low ambient temperatures, months of storage, or years of service. POWER-SONIC batteries are designed to power your equipment when needed. You can depend on it and so can your customer. AVAILABILITY VALUE POWER-SONIC batteries may not always be the lowest priced on the market, but you get what you paid for trouble-free service for years, enhancing the reputation of your product or installation. Success is measured by the bottom line, not short-sighted savings gained at the expense of high quality components. A full line of standard sizes is available along with a few unique but well conceived special designs. This extensive array of models, recognized by U.L.'s component program, puts design and sourcing flexibility at your fingertips. Fully stocked warehouses allow off-the-shelf shipments and guarantee on-time deliveries. PDIDE 11,ff;ffe~//III////II//II//////IIIIIII////IIIII /IIII////////I/I//Q///ll//lll///l/lllifff/J';111111'!!i s D NIC' POWER-SONIC CORPORATION Vic: 9/260 Wickham Road, Moorabin, Victoria 3189 Tel: (03) 553 4195. Fax: (03) 553 4917 NSW: Unit 5/60 Fairford Rd., Padstow, 2211 Tel: (02) 790-4444 Fax (02) 790-0246