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I i 20-band stereo graphic equaliser Registered by Australia Post. Publication No NBP 9047 Build a baby tower " AT computer ,, -~r - we show you how GaAsFet preamp for amateurs ~., ...... .J ... . r .. r., l,, / . / , / ~ A :~ 1 1 I.,,.:,•.,•:,.. I I I I ,, I ., '•' •• , I • I . I VI .. I __NI : 1 r' ,: . .. Precision Capacitors Today's high performance electronic equipment demands far more than just run of the mill capacitors. Whether your application requires close tolerance capacitors for equalisation and filter circuits, or low power factor at high frequencies for high-Q gyrators and oscillators, Wima is the brand for you. SILICON CHIP magazine has specified Wima 5% tolerance capacitors throughout in their new half octave stereo graphic equaliser. They did so to guarantee the performance over the whole audio frequency band. This could never have been achieved with ordinary greencaps. Polyester FOR GENERAL APPLICATIONS Decoupling, Coupling and by-pass applications. Adilam has a wide range of Wima precision capacitors in polyester, polycarbonate and polyproplene dieletric. All come in miniature moulded plastic cases which are clearly labelled. And they all have precision pin spacings (multiples of 2.5mm) so that you know they will always fit precisely into your boards. Wima has developed an extensive range of capacitors for use in pulse applications, in resonant circuits and switchmode power supplies, in line deflection circuits and other applications where long life and reliability at higher voltages are crucial. Polycarbonate Polypropylene FOR SPECIAL APPLICATIONS Where an almost constant temperature effet is required ; filters, memories, timers, balancing capacitors. Adilam Elecbonics ra: The Component Specialists FOR SPECIAL APPLICATIONS AT HIGH FREQUENCY For resonant circuits, switching mode power supplies, line deflection systems, temperature stabilized oscillator circuits MELBOURNESuite 7, 145 Parker Street, Templestowe 3106 PO Box 131, Bulleen 3105 Telephone: (03) 846 2511 Facsimile: (03) 846 1467 DISTRIBUTORS: ADELAIDE BRISBANE PERTH N.S. Electronics (08) 46 8531 St. Lucia Electronics (07) 252 7466 Pro-spec Distributors (09) 362 5011 Paper FOR RADIO INTERFERENCE SUPPRESSION Class X2 and class Y. Excellent flame retardent properties. For use in main RFI suppression applications. SYDNEYSuite 1, Ramsgate Plaza, 191 Ramsgate Road, Sans Souci 2219 Telephone: (02) 529 2277 Facsimile: (02) 529 5893 ■ AUGUST 1989 FEATURES 14 An Introduction to Stepper Motors by Steve Payor FANCY BUILDING your own computer? We show you how to assemble a 42Mb AT-compatible machine into a natty tower-style case. Details page 6. How these useful devices work 34 Amcron Preamp & Power Amp by Leo Simpson Among the best we've measured 96 Metrix MX52 5000-Count Multimeter by Leo Simpson Features frequency, dB and RMS AC measurements 102 The Evolution of Electric Railways by Bryan Moher Pt.22: the benefits of modern 3-phase electric locos PROJECTS TO BUILD 6 Build an AT Tower Computer by Greg Swain Step-by-step assembly details 26 Studio Series 20-Band Stereo Equaliser by Bob Flynn THERE'S NO NEED to run after the garbage truck in your slippers and jarmies. Our Garbage Reminder tells you when to put the garbage out. Construction starts on page 48. New design has very low noise & distortion 48 Build the Garbage Reminder by John Clarke Don't get caught with an overflowing bin 76 Low-Capacitance Scope Probe by Herb Friedman Uses parts from your junkbox SPECIAL COLUMNS 18 Vintage Radio by John Hill Rebuilding a vintage radio receiver ~~ l0~ ~ :____:,~~1))0 62 Serviceman's Log by the TV serviceman Toss yer - triple or quits! 66 Amateur Radio by Garry Cratt GaAsFet preamplifier for the 2-metre band 82 Computer Bits by Jennifer Bonnitcha Display adapters - from monochrome to thunderdome 90 The Way I See It by Neville Williams HDTV: don't hold your breath DEPARTMENTS 2 Publisher's Letter 3 Mailbag 46 Circuit Notebook 61 Bookshelf 85 Subscription Page 98 Product Showcase 108 Ask Silicon Chip 111 Back Issues 112 Market Centre N SPROING!! OUR serviceman really sprang into action this month. There's Greek drama, leaky cats, leaky tubes and ripping yarns. So turn to page 62. Electronics for Everyone Lack of space has once again prevented us from presenting Electronics for Everyone this month. We'll be back on track with this series in the September issue. AUGUST 1989 1 SILICON C HIP 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. S1ucoN CHIP is published 1 2 times a year by Silicon Chip Publications Pty Ltd . All mat erial 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 $4.2 per year { 1 2 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'l-l'ER Every new car can be burglar proofed One of the really great aspects of running a magazine is that you get to talk to a lot of people about electronics. Of course, we get a lot of reader feedback on the projects described in SILICON CHIP and some of that feedback generates ideas for new projects in the future. We have had a lot of feedback about our car projects and it is quite clear that people are very concerned about having their cars stolen. Our own car alarm projects have been very popular and commercial units are being sold by the tens of thousands every year. But when you think about it, most of this additional expense for the motorist is entirely unjustified, particularly for buyers of new cars. No, I'm not saying that car thieves are suddenly going to stop taking new models overnight. What I am saying is that it would be so easy for car makers to incorporate electronic security into their engine management systems. After all, every modern car with fuel injection has a computer for engine management. It would be so easy to add in an electronic security feature into the computer's ROM - it would be just a few lines of code. Then, before you started the car, you would press a few buttons on the dashboard to enter in a unique code known only to you. If anybody else tried to start the car without knowing the code, it would be immovable. How much would that feature add to the cost of a new car? Say $10 or even $20. It's a piffling amount but it could virtually stop cars being stolen overnight. I'm not saying that such a system would stop car thieves from breaking into vehicles and stealing accessories such as radios or fancy wheels but it would be a big improvement on the security available on new cars now. And with the computing power already available in engine management systems, why couldn't the system be extended to provide a complete car burglar alarm, with sensing on all doors, boot, bonnet and so on? Very little extra wiring would be required since it is already there. If electronic security can be incorporated into car radios such as the Eurovox to stop theft, why can't it be fitted to cars? The answer is that there is no reason why not. It should be available now. Leo Simpson MAILBAG Guide roller/pole assembly in VCR was OK I am writing in regards to the Serviceman story entitled "VCR: Very Crook Roller" in the April 1989 issue. I believe the guide roller/slant pole assembly is perfectly OK. When the tape is loaded, the assembly is pushed into a socket of some description and held in place by the loading ring which is spring loaded. On some machines, the socket or the roller and slant pole or its base will be adjustable. The adjustment on the tape supply side is very critical to achieve an even RF envelope pattern. Note that this is normally a factory adjustment and to my memory is not mentioned in any service manual. As a technician of more than 30 years I find your articles very interesting and the Serviceman's Log is usually the first article I read, so keep up the good work. D. Littleby, MTETIA Yokine, WA Easy to understand projects After getting other magazines for the last 20 years, I found that your magazine is the answer for easy to understand and to make projects keep it up! I recently saw your magazine in the bookshop and after two trial copies have ordered it permanently. I ordered all back copies except January 1988. I would suggest that perhaps a lot of your new subscribers would like that issue. What about a reprint? Maybe you could put an ad in the magazine and get some pre-orders. Thank you for a good magazine. T. H. Radersma Wellington Using Wordstar to program the LED Message Board In the fourth article on my LED Message Board project featured in the June 1989 edition, there is a rundown on loading the message board with data from a computer system. A word processor or similar text editor which produces ASCII text is sug- gested, however it also states that "Wordstar is not suitable". Poor MicroPro. The statement should have read "Wordstar is suitable". Wordstar can be used in the non-document mode for editing text suitable for the Message board. While we are on this subject, how do you insert the required control characters into your ASCII text with Wordstar? Say you wanted to insert a control C ['C) into the text. Hold down the Ctrl key and press and release P, then press C. A " AC" will appear prior to the current cursor position. Don McKenzie Tullamarine, Vic Service manuals should be supplied With reference to your editorial in the May issue on the subject of circuit diagrams, as an electrical engineer I agree with you fully. However, in any modern equipment there is often at least one microprocessor. Thus to service this item, some knowledge of the program steps, together with the corresponding output states, is required. This means that full listings of EPROMs etc must also be provided along with the service information. I have a standard clause or three to be tacked onto any purchase or enquiry, which I have enclosed for your information. Note that this is sadly bypassed in most cases due to the submission of initial lower dollar quotes. Most non-service oriented people don't care about service some years down the track. Most non-electronic service personnel, including engineers of other disciplines, do not realise the technology turnover and update from model to model, or even issue to issue, of electronic equipment. As long as the outward working ability of the gear is the same, the manufacturers can and do completely revamp the circuitry. Thus what may have had relays last year now has Triac outputs and microchips internally - along with ever increasing EMC/EME problems (and that's another story). The ruse some companies (real big SILICON CHIP, PO Box 139, Collaroy Beach 2097. ones) waffle on about is "we don't supply such information because it's under warranty for X amount of time"! Never mind that after this time the model is out of date and information is truly not available, if it ever was. The supplier or dealer may have also gone out of business. "We no longer handle that brand" or "we only handle the model after yours" are excuses I hear from week to week. The need for service manuals also applies to most things including cars. If you don't buy them as soon as you can after purchase, too bad. Most companies only print so many copies and after that, well, start praying! Another topic which no-one has ever addressed is how the hell are we going to service surface mounted devices in equipment? Who is going to buy stereo microscopes, and kilobuck workstations for such little things! That's assuming of course that the correct replacement part is available from the component supplier without having to buy them by the hundreds or more. I've been in the electronics game for over 25 years now and despite all the hype about "throwaway" boards during that time, it never came about - often because the manufacturer is unable to supply a replacement that does the same job or the dollars involved in obtaining same. Well those are my additions to your pleas, but I bet most of them were only preaching to the already converted. I. Morrison North Ward, Qld Service manuals and the Trade Practices Act Your editorial in the May edition of SILICON CHIP prompted me to enclose a copy of a section of an old newspaper column from 1971. I would imagine that the Commonwealth Trade Practices Act would apply equally to all consumer appliances - mechanical, electrical and electronic; ie, service manuals should be available, no matter what the product. N. Cocking North Lambton, NSW AUGUST 1989 3 hat's right! Now you can build your own ultra high performance PC/AT, with the exact options you need, and save a fortune into the bargain. The Electronic Solutions Project ATs feature 12MHz and optional 20MHz motherboards for unmatched speed . They are complemented by fast 1:1 interleave disk controllers and a 42MB 28 msec NEC hard disk drive (optional 20MB) . The floppy disk controller supports the full range of formats: 360K 5¼", 1.2MB 51/4" and the new 31/2'' (720K and 1.44MB) formats. For a limited period, we are offering big savings, both on the basic configurations and on the broad range of options shown opposite. If you want the best AT on the market, and you can use a screwdriver, the Electronic Solutions Project ATs are the only choice worth looking at. T 1. 4 1. Compact "Mini-tower" case and 200W power supply. 2 . High quality en hanced AT layout keyboard. 3. Monochrome graphics video card. 4. 12MHz zero wait-state "all-in-one" AT motherboard (20MHz option). PRICE LIST 12MHz AT PROJECT AT COMPUTERS . . . . . . . . . . . . . . . . . 12MHz all-in-one motherboard . . . . . . . . . . . . . BabyTowercase . . . . . . . . . . . . . . . . .. .. Power supply for Baby Tower . . . . . . . . . . . . . . MGACard . .. . . . . . . . . . . . . . . . . . . . . 101-key Keyboard . . . . . . . . . . . . . . . . . .. 1.2MB Floppy drive . . . . . . . . . . . . . . . . . . . MS-DOS 4.01 . . .... . . .... . . . . ..... Total . . . . . . . . . . . . . . . . . . . . $1,431 20MHz AT . . . . . . . . . . . . . . . . . . . . . . 20MHz AT Motherboard . . . . . . . . . . . . . . . . BabyTowercase . .. . . . .. .. . . . . . . . . . . PowersupplyforBabyTower . . . . . . . . . . . . . . MGACard . . .. .. . . . . .. . .. . . . . . . . . 101-key Keyboard .. . .. .. . . . . . . . . . . .. 1.2MB Floppy drive . . . . . . . . . . . . . . . . . . . HOD/FOO controller card . . . . . . . . . . . . . . . . 1S + 1P card . . . . . . . . . . . . . . . . . . . . . . MS-DOS4.01 . . . . . . . . . . . . . . . . . Total Normal price . . . . . . . Project Price $549 . . . . . . . . . $495 $149 . . . .. . . . . . . . $135 $145 . . . . . . . . . . . . . . . $130 $115 . . . . . . . .. . .. .. .. $99 $115 . .. . . . . . . . . . . . . . $99 $199 . . . . . . . . . . . . . . . $195 $159 . .. . . . . . . . . . . . . $145 . . . . . . . . . $1,298 Normal price . . . . . . . $945 . . . . . . . . . . . $149 . . . . . . . . . . . $145 .. . . . . . . $115 . . . . .. .. . . . $115 . .. . . . . . . .. $199 . . . . . . . . . . . $249 . . . . . . . . . . . $75 . . . . . . . . . . . . $159 . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . $2,151 Project price . . . . $899 . . .. $135 .. .. $130 . . . . . $99 . . . . . $99 . . . . $195 . . . . $225 . . . . . $69 . . . . $145 . . . . . . . . . $1,996 PROJECT AT OPTIONS 640K RAM 18 x 256K & 18 x 64K chips. (120nS) Normal RRP: $432 Special project price: $395 360K 5.25" FLOPPY DISK MONITORS CAT DD1157C 1MB RAM 36 X 256KB RAM chips (120nS) Normal RRP: $594 Special project price: $549 Special project price: $175 2MB RAM 18 X 1MB RAM chips (120nS) Normal RRP: $790 Special project price: $750 42MB NEC HARD DISK 28mS CAT DD3146H 42 Megabyte 3.5 inch hard disk drive. Access time track to track Bms. Average seek time 28ms. • Formatted capacity 42.3 MB • Non-operating shock: 40G CAT DD1137H 14" AMBER or GREEN MONITOR 3.5 inch slimline micro-floppy drive These high reliability drives feature low power consumption and high reliability. Incorporate an autoshutter and head load solenoid to protect media. • Data transfer rate 500 kbits/sec • Power dissipation : 0.01 SW standby, 1.5 steady state • Seek time : 3ms • Size: 101 .6mm x 25.4mm x 130mm, Weight : 0.39kg • Data transfer rate 625 Kb/sec • Power consumption 9.2W 1.44MB 3.5" FLOPPY DISK Special project price: $199 • Size: 41 .3mm x 101 .6mm x 146mm Normal RRP $895 Special project price: $699 EGA CARD CAT VC1629C TTL Monochrome monitor. The models ACMA (amber) /ACMG (green) are high-resolution TTL monitors, designed to work with the hercules compatible graphics video adaptors. The monitors have 14 inch flat screen, antiglare tubes, making them an excellent choice for both text and graphics. CAT ACMA Normal RRP: $249 Special project price: $199 EGA MONITOR The ACM EGA is a 14" EGA colour monilor. A dot prtch of 0.31 mm and non-glare tinted screen make it ideal for enhanced graphics and applications requiring colour graphics generally. CAT ACMEGA Normal RRP: $765 Special project price: $645 VGA MONITOR The CAT. ACM VGA. is a 14" VGA colour monitor with a resolution up to 640 x 480 dots. 30MHz bandwidth and .31 mm dot pitch make it suitable for both text and graphics. Analogue drive allows display of up to 256,000 colours. Normal RRP: $875 20MB NEC HARD DISK CAT DD5126 Special project price: $685 Special project price: $395 This enhanced graphics adaptor is an exclusive design to upgrade the graphics display of the IBM PC/XT. AT and compatibles to a high resolution display. Compatible with the complete expanded IBM Enhanced Graphics Adaptor and providing 256KB standard video memory, it is also fully compatible with the IBM Monochrome Display Adaptor (MDA), Hercules Graphics Adaptor (HGA). and Colour Graphics Adaptor (CGA). HARD DISK DRIVE CARD Special project price: $249 5.25 inch half height hard disk drive. Average seek time65mS. Normal RRP: $595 CAT DCAH EGA/VGA MULTISYNC MONITOR The Multisync monitor fetaures a 14" colour display which automatically scans all between 15.5-35kHz (horizontal) x 50-70 (vertical) with TTL and analog inputs. It is suitable for CGA, EGA and VGA operation up to 600 x BOO dots. In analog mode it can display an unlimrted palette of colours. A text mode switch provides monochrome green or amber displays. CAT. ACMM Normal RRP: $1275 Special project price: $899 VGA CARD Box 426 Gladesville 2111, Phone (02) 906 6666, FAX (02) 427 2542. Gosford (042) 24 3405. • Includes all cabling Normal RRP $275 CAT VCBOO This card offers complete register level compatibility with IBM's VGA stamdard. A range of drivers providing resolution up to BOO x 600 pixels for Ventura, Windows, Pagemaker & Autocad are included. Combined with a Multisync or VGA monitor, it provides unmatched resolution and a palette of up to 256,000 colours. Facilrties include Complete CGA/MDA/EGA compatibility: hardware zoom and smooth panning: 132 column text display for Lotus, WordPerfect etc. Normal RRP: $495 Special project price: $199 Special project price: $475 • All products carry a full 3 month warranty. The DCAH is a high per1ormance 1: 1 interleave hard disc controller using the latest Western Digital chipset. Automatic optimising circuitry built extracts maximum performance from the hard disk. • Operates at up tci 16MHz bus speed for unmatched data transfer rate • Supports MFM encoded ST506/412 interfaced drives • CRC and ECC functions to ensure data integrity We accept : Bankcard, Mastercard, & VISA. Mail orders our specially. All prices include sales tax. Note: Products may vary in appearance from those pictured . In all cases they will perform to the same or a better standard. • All products carry a 1'4 day money back guarantee (except software). • All cards come with full documentation ■ 6 SILICON CHIP If you can use a · screwdriver and follow a few simple instructions, you can build this highperformance ATcompatible computer. It uses a 12MHz ·zero wait state motherboard and is built into an attractive tower case which will save space on your desk. By GREG SWAIN .\;[ -V :'.~ j"" ',f ?\~D/.- ~ -'=. ~~~$ ·~,~-,-»,v r- -~-,~~:Iii When Electronic Solutions advertised their new 12MHz AT-compatible motherboard in our May issue, we were immediately interested. Suddenly, for just $495, you could buy a motherboard incorporating features that are normally only obtained by plugging extra cards into the expansion slots. Those extra features included two onboard serial ports, one parallel port, a floppy disc controller, an integrated hard disc adaptor, and an on-board clock. And the new motherboard was fast - a 12MHz zero wait state machine is no slouch when it comes to running software. Other features of the motherboard included an 80286 microprocessor, provision for up to 4Mb of RAM (random access memory), "Award" BIOS with built-in setup, dynamic input/output control, and 6 expansion slots. Naturally, it is also fully compatible with the IBM PC/AT. THE MAJOR COMPONENTS of the ATcompatible kit (clockwise from top left): 14-inch monochrome monitor, 12MHz motherboard, tower case, 1.2Mb 5.25-inch floppy disc drive, 42Mb hard disc drive and keyboard. In the centre of the picture are the three optional graphics adaptor cards (MDA, EGA & VGA), the hard disc controller card and the optional 3.5-inch 1.44Mb floppy disc drive. AUGUST 1989 7 KE BOARD S CKET S PARALLEL PORT FLOPPY DISC CONTROLLER t IAL P RT THIS IS THE BABY 286AIO motherboard. It's a 12MHZ zero wait state machine with on-board serial and parallel ports, floppy disc controller, 6 expansion slots, "Award" BIOS with built-in setup, and provision for up to 2Mb of RAM. A practical computer But forget about such things as speed and memory and BIOS for the moment. What do those extra onboard functions mean in terms of building up a practical computer? Let's tick off some of the advantages. For starters, you can scratch the need for an input/output (1/0) card - the 1/0 is built directly onto the motherboard. Second, you don't need a floppy disc controller card. And third, if you use an AT-bus integrated hard disc such as a Miniscribe 8051A, you don't need a hard disc controller. As well as leaving expansion slots clear, that can all add up to some big dollar savings. So, we thought, why not approach Electronic Solutions with a view to building up a complete kit computer at a special price? Fur8 SILICON CHIP ther, why not go one better by housing it all in one of those natty new compact tower cases? A tower case takes up far less bench space than a conventional case and, to our mind, is a far more attractive format. The result is the machine presented on these pages. Our aim with the prototype was to bring the price in at under 3000 bucks and so we specified the following: 1Mb (one megabyte) of on-board RAM, a 42Mb hard disc drive, a hard disc drive card, a 1.2Mb floppy disc drive, a monochrome display adaptor (MDA) card, a 14-inch monochrome monitor and MS-DOS 4.01. This gave an all-up cost of $2944, including the monitor and keyboard. Considering the power and performance of the machine, that represents quite good value. Depending on your requirements (and your budget), you might want to specify quite different options for your machine. Want to save $304 at the expense of disc space? - simple, just specify a 20Mb hard disc drive in place of the 42Mb unit. Perhaps you don't need 1Mb of onboard RAM? No problem, just reduce the on-board RAM to 640K and save another $150. Taken together, these two "compromises" reduce the total cost by $454, resulting in a 20Mb hard disc machine with 640K of on-board RAM and a 1.2Mb floppy disc drive for $2490. Alternatively, you might want to build a machine with a few more features. Apart from the features already listed, the options include 1.44Mb 3.5-inch floppy disc drives, expanded memory (up to 4Mb), and EGA (enhanced graphics adaptor) or VGA (video graphics array) cards. By the way, you must use a hard disc drive card with the two hard disc drives that will be supplied. This is because neither of these drives is an AT-BUS integrated type. We'll have more to say about this later on. DOS 4.01 As part of the deal, Electronic Solutions will be supplying Microsoft MS-DOS 4.01 with the kit. This version of DOS offers several new features as compared to older versions. Among these are enhancements to the SELECT command which greatly simplifies MSDOS 4.01 installation and system configuration. In this version, the SELECT command is now a full-screen program that takes you through installation and system configuration step by step. It also creates the corresponding config.sys and autoexec.bat files for you, plus a separate DOS directory. With MS-DOS 4.01 , you don't have to worry about FDISK and all that stuff. Another advantage of MS-DOS 4.01 is that it can support hard discs with capacities larger than 32Mb. Earlier versions of MS-DOS can only recognise up to 32Mb of disc space, which meant that a 42Mb drive had to be partitioned. With MS-DOS 4.01 , you don't have to worry about partitioning the disc. Note that both the 20Mb and 42Mb hard disc drives will be supplied with low level formatting so that setting up will be straightforward. The tower(ing) case We've already briefly mentioned the tower case and our reasons for choosing it. In fact, we reckon this format will become very popular. The "Baby Tower Case" specified measures just 180 x 410 x 330mm and is supplied with the 200W power supply bolted into position. Also supplied with the case is a hardware pack. In addition to a small loudspeaker and the blank backplane brackets, this pack also contains such mundane items as screws, fibre washers, plastic standoffs [for the motherboard), rubber feet and keys (to lock the keyboard). It might look complicated from TABLE 1: WHAT IT COSTS BASIC KIT 1 2MHz Baby 286AIO Motherboard .. .... .... ... .... .... ... .... ...... ... $495 Baby Tower Case ...... .. ... .. ..... ........ ..... .... ..... .. ... ... ........ ...... $1 35 200W Power Supply ......... ..... ... ... .. ........ ...... ......... ... .. .... ... $130 Monochrome Display Card (MDA) ... .... ........ ..... ............ ..... ... $ 99 101 -Key AT Keyboard ... .... .... .. ... ........... .. .. ... .. .. .... ...... ... .... $ 99 1.2Mb Floppy Disc Drive ... .. .......... .... ... ... ... .... ...... .... ... ...... . $195 MS-DOS 4.01 ................. ...... .... ..... .... ....... .. ......... .... ........ $145 TOTAL $1298 OPTIONS 640Kb RAM (18 x 256Kb + 18 x 64Kb) ..... .. .. .... ..... ...... ... ... $395 1 Mb RAM (36 x 256Kb) .. .. ......... ....... .. ..... ...... ........ ........ .... $549 2Mb RAM (18 x 1 Mb) .... .... ......... ... .... .. ..... ... .. .. .. ..... ..... .. .... $750 360Kb 5.25-inch Floppy Disc Drive .. ........ ..... .. ...... .. .... ........ $175 1.44Mb 3 .5-inch Floppy Disc Drive ..... ... ... ... .... ... ... ....... .. .... $199 20Mb Hard Disc Drive (Type 41) ... ... .... ... .. ... .... .... .... .. .... .. .. . $395 42Mb NEC Hard Disc Drive (Type 42) ... ....... ..... ... .. .... .... .... .. $699 Hard Disc Controller Card ...... .... .... ... ...... .... ... .... ... ....... .... ... $1 99 Enhanced Graphics Adaptor (EGA) Card .. ...... ...... ..... .... ..... ... $249 Video Graphics Array (VGA) Card .. .... ......... .... ... ... ..... ..... ..... $4 7 5 14-inch Monitor (Amber or Green) ... .... ...... ..... ... ... ...... ... .. .... $1 99 EGA Monitor ... ...... ..... ... ... ...... .. .... ... ........ .... ... ...... ...... ....... $645 VGA Monitor .... ... .. .. ....... ..... .. .... .... ... .. .... .. ..... .. .. .. ... .. .... .. .. . $685 EGA/VGA Multi-Sync Monitor ..... ......... .. .. .. .. .. .. .. .. .. .... ... ....... $899 Note: these are special kit prices and are less than normal retail prices. The parts are available from Electronic Solutions (see advert pages 4 & 5). the photographs but installing all the parts in the case is quite straightforward. Mostly, it's just a case of bolting each part into position and then hooking up the necessary ea bles and wiring connectors. Well , almost but not quite. There's a definite order to the assembly and there are a number of things to check before installing the disc drives and the motherboard. We'll go through each of these things in turn, just so that there 's no confusion. To simplify things, we'll assume that you're building a machine with similar specifications to ours. If you've specified different options, the order of assembly will be similar so you should have no problems. The disc drives Before mounting the disc drives, it will be necessary to identify and record the leads to the front panel LEDs and switches on the case. On our machine, the yellow and white leads went to the turbo switch; the blue and white leads went to the reset switch; the red and white leads went to the hard disc LED (HDD); and the white, green, black and red leads went to the keyboard lock and power LED. Note that, where LED connections are involved, the cathode lead is always the white one. Don't just accept our colour codes as gospel, though. The colours used on your case may be different so check first. The hard disc drive can now be installed right at the bottom of the disc cage. First, remove the plastic front panel from the drive [just undo the screws), then slide it into the rear of the disc cage with the diecast section upermost. The drive A UGUST 1989 9 1.2Mb FLOPPY DISC · ., , ;r ·- ·,:;_,' -1\, 0 HARD DJ~.C IT MAY LOOK complicated but it's mostly a matter of installing the major parts in the case and then hooking up the control cables and front panel wiring. Take care with the switch and jumper settings (see text). can then be secured using four machine screws (two on either side). The switches on the hard disc drive should be correct if left at the factory settings. For the record, SWl-1 should be set to OFF while SWl-2 to SWl-8 should all be ON. Similarly, SW2-1 should be set to ON while SW2-2 to SW2-4 should be power supply leads can be connected to the on/off switch on the front panel. There are four leads in all and these are simply pushed onto the switch terminals [careful one section of the switch must switch the black leads while the other must switch the white leads). OFF. Before installing the motherboard, you first have to install the RAM chips and check a number of switch and jumper settings. The RAM chips are plugged into six rows of six sockets and these are labelled Ul-U36 on the motherboard. Page 17 of the manual (supplied with the motherboard) shows how to mount the RAM. If you want 1Mb of on-board RAM [ie, 640Kb base memory plus 384Kb extended), then it's simply a matter of plugging 36 256Kb (41256) RAM chips into the 16-pin sockets. The wider 18-pin sockets are for the larger 411000 1Mb RAM chips. The 640Kb memory size requires a mixture of 256K 41256 chips and Now for the floppy disc drive once again, it should just be a matter of leaving everything at the factory settings but it should still be checked to make sure everything is correct. The jumpers for DX, MON, DEN and HDE should all be set to position 1, while USE and DCG should have their jumpers set to position 2. Install the floppy disc drive from the front of the case and adjust it so that the tapped holes line up with the slots in the disc cage. Check that the front panel of the drive is flush with the case, then secure the drive using eight machine screws. With the disc drives secured, the 10 SILICON CHIP The motherboard 64K 4164 chips. In this case, the 41256 devices are plugged into sockets Ul-U18 while the 4164s are plugged into sockets Ul 9-U36. Don't mix the two types on the same row otherwise you will run into problems. Note that the RAM chips can be damaged by static electricity so try to avoid touching their leads when installing them on the board. Also, make sure that all the chips are correctly oriented - the notched ends go towards the expansion slots. OK, we've got the RAM chips installed. It's now a matter of working through the manual supplied with the motherboard and checking off all the switch and jumper settings. Mostly, it's simply a matter of leaving the jumper (or switch) at the factory setting so we'll just mention the changes and the main things to watch out for. First up, you have to set DIP switch SWl according to the amount of RAM installed on the board. The factory setting is for 1Mb of RAM but be sure to set SWl-1, SWl-2 and SWl-3 as required for other RAM sizes. After that, you can flip through the manual until you come to Section 2.13: Display Adapter Selection (SWl-5). The factory setting here is for CGA, EGA or VGA. We opted for an MDA [monochrome adaptor) card and so we moved SWl-5 to the OFF position. You should also check the switch settings for the floppy disc controller and the hard disc adaptor. The on-board floppy disc controller must be enabled (SW2-5 ON) while the hard disc adaptor should be disabled [SW2-6 OFF and Jl 7 set to position 1-2). The motherboard is secured using plastic standoffs [which are first fitted to the board) and a number of metal standoffs which are first screwed into the case. Fit the standoffs, then decide whether you wish to use front or rear entry for the keyboard connector. If you want to use the front entry, which we think is the most convenient, insert the plug connector into the back of the motherboard keyboard socket before pushing the board all the way down. Once the board is locked into white) is later plugged into the hard disc controller card instead. The next most logical step is to connect up the power supply leads. Locate two 4-pin polarised connectors and plug these into the floppy disc and hard disc power connectors. For the motherboard, plug the 6-pin connector with the orange lead into the rear 6 pins of the power connector (Pll). The other 6-pin connector then plugs into the other 6 pins of Pll. Plug-in cards THE SYSTEM SETUP is performed by pressing and holding down the CTRL, ALT & ESC keys simulataneously. After that, you simply step through and correct each item in turn using the arrow keys. This photo shows the setup for our system. Before plugging in the MDA card, check that there are no shorting plugs on JPZ and JP3. If you are using a colour adaptor card (EGA or VGA), then you must set the various DIP switches and jumpers to suit your monitor (these settings will be spelt out in the manual). You will also have to check SWl-5 on the motherboard. Once you are satisfied that all the switch settings are correct, plug the card into one of the expansion slots and secure the backplane bracket to the case. On the disc controller card, check that JPl is closed (single crystal version only) and that JP5 is open. JP3, JP4 and JP6 should all be set to position 2-3. If everything checks out, plug the controller card into another of the expansion slots and plug the connector from the HDD LED into JPZ (the white lead should be adjacent to C24). Cables & battery THIS CLOSE-UP VIEW shows the mounting details for the loudspeaker and for the hard disc drive. The drive is installed with the diecast section uppermost. position (by sliding the heads of the plastic supports into the narrowed channels), the board can be secured to the metal standoffs using the screws provided. Be sure to use a fibre washer under each screw head to prevent shorts on the board. You can now install the speaker (see photo) and proceed with hooking up the various connectors from the front panel LEDs and switches. Pt.3 of the manual lists the pin assignments for all the on-board connectors and this should be followed carefully. Note that there is no provision on the board for the turbo switch connector and so this is simply left unused. Also, don't use the onboard hard disc LED connector (P4) - we've disabled the on-board hard disc adaptor, remember? The connector for the HDD LED (red & The interconnecting cables can now all be installed. Plug the 10-way connector into serial port 1 on the motherboard and the 25-way connector into the parallel port, then secure the DB-25 connectors to the back panel. Note that the red stripe on each cable denotes pin 1. The floppy disc controller cable is installed directly between the motherboard and the edge connector on the back of the drive. Note that the end with the " flipped" sections is installed on the drive while the other end goes to the motherboard. The middle connector is used only if two floppy disc drives are installed. The hard disc drive is hooked up by running a 34-way cable to Jl on AUGUST 1989 11 AFTER SYSTEM SETUP and MS-DOS installation, the computer will boot directly from the hard disc. Note that we were also in the process of installing a 3.5-inch 1.44Mb floppy disc drive when the photos accompanying this article were taken. the controller card and a 20-way cable to J2. There's just one more thing to do before switch on - the battery installation. You must do this otherwise you will lose the initial set-up instructions as soon as you turn off the computer. So install the battery now. It can be secured to the underside of the power supply using the Velcro material supplied. The battery lead then plugs into the P13 connector on the motherboard with the red lead to pin 1. Switch-on Connect up the monitor, keyboard and power cable and switch on. After the BIOS message appears, the machine will go through a series of tests and then display an error message at the bottom of the screen. This is perfectly normal and is solved by running the SETUP program. To do this, press and hold down the CTRL, ALT & ESC keys 12 SILICON CHIP simultaneously so that the screen displays the "Award Software CMOS Setup". It's now simply a matter of entering in the date and time and then using the arrow keys to specify the disc drives fitted and the amount of memory. Note that the 42Mb hard disc drive is a type 42 while the 20Mb drive is a type 41. When all the information is correct, press F10 to record the changes and then press F5. The machine will now go back to the BIOS message and then "hang". We're on the home straight. You now have to install the MSDOS so that the machine will look first at the floppy disc drive and, .if nothing is there, boot from the hard disc. Reach for the DOS pack, take out the "User's Guide .and User's Reference", and turn to page 19. There you will find a step-by-step guide for installing the MS-DOS using the Install and Select programs. To start this procedure, turn the computer off and insert the Install disc into drive A. Now switch on again and wait for the Welcome screen to appear. After that, it's simply a matter of following the onscreen instructions. At the end of this procedure, your computer will boot up directly from the hard disc. By the way, it is a good idea to create a back-up copy of your MSDOS disc (ie, of the working disc created during the installation process). This requires a blank unformatted floppy disc and this will supplied by Electronic Solutions as part of the DOS package. The bottom line The bottom line? - this ATcomputer kit is easy to build, easy to get going and easy to set up. There are lots of options so that you can build it just the way you want and the price is highly competitive. And it's fast - boy, is it fast. You can have one for your very own by contacting Electronic Solutions, PO Box 426, Gladesville, NSW 2111. Phone (02) 906 6666.~ r-;----------i1 I I I I I I I I VERBATIM DATALIFE PLUS Teflon* Coated (ALL PRICES PER BOX OF 10 DISKS) 5 1/4" DS/DD C12522 ................................. $34 5 1/4" High Density C12523 ............................ $64.95 I I I I I I I I L----------.J 80 x 3 1/2" DISK STORAGE UNIT • Holds up to 80 x 3 1/2" diskettes. • Smoked plastic hinged lid • Lockable (2 keys supplied) C16038 .. ... .... only $16.95 40 x 31 /2" DISK STORAGE UNITS • Holds up to 40 x 31 /2" diskettes • Lockable (2 keys supplied) • High impact plastic lid and base C16035 .. .... ... only $14.95 50 x 5 1/4" DISK STORAGE • 50 x 5 1/4" Disk capacity • Smoked plastic hinged lid • Lockable (2 keys supplied) "NO BRAND" DISKS Now you can buy absolute top quality disks that are also the cheapest in Australia! They even come with a lifetime warranty, which Indicates the quality of these disks. So why pay 2-3 times the price for the same quality? Packs of 10, D/S DID without boxes, or brand name, just their whitepaper jacket, and index label. (5 1/4" disks includes write protects) 5 1/4" 2S/2D "NO BRAND" DISKS 10+ DISKS 100+ DISKS 1,000+ DISKS $6.50ea $6.25ea $6.00ea 51 /4" HIGH DENSITY DISKS 10+ DISKS $21ea (DOUBLE SIDED) 100+ DISKS $20ea 1,000+ DISKS C16025 .........only $14.95 100 X 5 1/4" DISK STORAGE UNITS • 100 x 5 1/4" disk capacity • Smoked plastic hinged lid • Lockable (2 keys supplied) C16020 ......... only $15.95 IBM* XT* 640K RAM TURBO COMPATIBLE COMPUTER Check these features and our prices. We're sure you 'll agree they·re exceptional value for money! • Final assembling and testing in Australia! • Fast TURBO Motherboard • AT' style keyboard • Tested by us for 24 hours prior to delivery! • 8 Slot motherboard • 12 months warranty! • 150W power supply 640K RAM TURBO COMPATIBLE COMPUTER 2 x 360K Disk Drives, Multifunction Card, Colour Graphics, Disk Controller, 1 Serial, Parallel Port (Clock) ....................$1, 195 WITH 20 M/BYTE HARD DISK : & single 360K Disk Drlve ..$1 ,495 & dual 360K Disk Drlves ...$1,695 120 x 5 1/4" DISK STORAGE UNITS • Holds up to 120 x 51 14·· diskettes • Lockable (2 keys supplied) • High impact plastic lid and base WITH 40 M/BYTE HARD DISK : & single 360K V.C. H.D...... $2,095 & dual 360K V.C. H.D ......... $2,295 C16028 ...... ... only $19.95 $19ea 386TOWER PC The 386 Tower PC Is a high performance system that"s IBM• AT' compatible. However, the 386 Tower PC gives you 2-5 limes the performance. FEATURES: • Intel 80386-16MHz microprocessor • Switchable 16/20 MHz • 2 M/Byte fitted. Total memory expandable up to 16 M/Byte • Up to 2 M/Byte or 8 M/Byte RAM modules on system board or on RAM card • Option for 80287 & 80387 coprocessor socket • Operates in page mode with Interleave memory subsystem , Shadow RAM supported to allow system BIOS to be executed on system memory instead of slower EPROM • Four 16-bit 1/0 slot. Three 8-blt 1/0 slot, and one 32•bit memory slot • 8042 keyboard controller interface for AT' compatible keyboard • Seven direct memory access (OMA) channels • Chips and Technology chip set • AMI 386 BIOS/ Phoenix 386 BIOS/ AWARD 386 BIOS (AMI lilted) • 50 M/Byte hard disk. 42 M/Byte formatted. Voice Coil. • EGA card • 3 1/2" drive 1.44 M/Byte X20070 .................. $5,995 3 1/2" 2S/2D "NO BRAND" DISKS Suitable for IBM, PS/2, Macintosh, Atari, etc. $21 Bffi~lill GRIP CLIP COPY HOLDER • Attaches to the top of your monitor • Put your copy right where you need it spring clip to hold paper • Velcro at mount for easy remova l VERBATIM DISKS C21065 .................. $14.95 (ALL PRICES PER BOX OF 10 DISKS) DESCRIPTION 1-9 BOXES 10+ BOXES 3 3 3 5 5 5 5 $37.95 $43.95 $89.00 $21.00 $24.00 $70.00 $39.00 1/2" 1/2" 1/2" 1/4" 1/4" 1/4" 1/4" 1S/2D ...............$39.95 2S/2D ............... $46.95 2S/HD ........ ...... $99.00 1S/2D.. ............. $22.00 2S/2D ............... $26.00 2S/4D ............... $75.00 2S/HD ...... ........ $41.00 MAGIC STAGE A working bench for your Mouse. •High quality ABS plastic and anti-static rubberised top ,siationary holder •Includes pull-out shelf for Mouse •Dimensions : 280 x 260 x 25mm • Fits over keyboard C21080 ........ ...... ... $24.95 BABY AT* COMPATIBLE COMPUTER! 2M/B RAM $2,695 • Final assembling and testing in Australia! • 4 M/Byte Main Board, 2 M/Byte fitted • Switchable 8/10/12 MHz • 1.2 M/Byte Floppy Disk Drive • 80286 CPU • Colour Graphics Display Card • 8 Slots • Floppy & Hard Disk Controller • Printer Card and RS232 • Keyboard • 200W Power Supply • Manual • 6 Months Warranty • Size: 360(W) x 175(H) x 405(D)mm With 20 M/Byle Hard Disk.$2, 195 With 40 M/Byle V.C. H.D.... $2,395 With 80 M/Byte Hard Disk ..CALL TOWER COMPUTER CASING Remount your computer to give it that professional look. • Accepts XT, AT, Baby AT and 386 boards • Horizontal lull height hard disk drive mounting • Room for 2 x3 112" and 2 x 5 1/4" floppy drives • Full height HOD plus Ian mount • Size: 165(W) x 600(H) x 500(0) X11105 ........ ......... ....$295 An introduction to: Ever wondered how stepper motors work? Here's a practical run down on these useful devices. By STEVE PAYOR Most semiconductor manufacturers produce a range of power ICs for driving stepper motors. The data sheets for these ICs cover the drive requirements for stepper motors quite well but the purpose of this article is to provide some practical experience with the stepper motor itself. By practical we mean just that if you want to learn all there is to know about stepper motors, you will need to wire up 4 pushbuttons, 4 diodes and a 1.5V dry cell. With this simple test circuit you can demonstrate half-step and full-step drive modes, and regenerative braking. DIRECTION OF MAGNETIC FIELD FROM PHASE 1 1 Fig.1 shows a "conceptual" model of a typical 4-phase stepper motor. (They are not actually built this way but the operation is easier to visualise). The rotor can be thought of as a permanent magnet which aligns itself with the direction of the applied magnetic field. By energising one winding at a time, the rotor can be made to move to any one of four positions, 90° apart (Fig.la). By energising two adjacent phases simultaneously, the rotor can be positioned in another four orientations, mid-way between at 45° as shown in Fig.lb. The latter driving scheme is more commonly used since the torque is RES~~[tNT~ MAGNETIC FIELD FROM PHASE 1 MAGNETIC FIELD FROM PHASE 2 ~ N ~~] rooofooo7 $2 V+ (A) ,t,4 $~ .,.. Y+ $4 (B) Fig.1: simplified representation of a 4-phase stepper motor. When phase cf>l is energised, the rotor aligns itself as shown in Fig.la. When cf>l and c/>2 are energised, the rotor moves to the position shown in Fig.lb. 14 SILICON CHIP greater when two windings are energised. By alternating between the two driving schemes, it is possible to obtain twice as many steps per revolution - this is known as the "halfstep" mode. We'll have more to say about this later. A typical stepper motor has a step angle of 1.8 ° so if you can imagine a rotor with 50 poles, and the coils of the stator duplicated 50 times around the circumference of the rotor, you have a pretty fair idea of how it works. By the way, the term "4-phase" stepper motor is really a misnomer. It is actually a 2-phase motor to a power engineer. Yes, it does have four coils, but energising <J,3 or <J,4 is no different to energising <J,1 or <J,2 with the current reversed. Having four windings just simplifies the drive circuitry, since only four SPST switches to ground are needed - these are usually just NPN power transistors. However, only half of the windings can be active at any one time, so large, high power stepper motors usually dispense with the centretapped windings and use a single heavy-duty winding for <J,1 and <J,3, and ditto for <J,2 and <J,4. The drive circuitry must now be capable of reversing the current through the windings so two "H-switches", each containing four power transistors, are required. (See the Railpower train controller circuit, SILICON CHIP, April 1988, for a typical example of an H-switch, using PNP and NPN Darlington devices). Demonstration circuit Anyhow, enough of the theory. The best way to learn is by doing, so if you have a stepper motor lying around somewhere, dust it off and wire up the simple demonstration circuit of Fig.2. A 1.5V "D" cell will provide enough drive to demonstrate the torque capabilities of the motor. Four pushbuttons enable you to drive the motor manually through "full step" or "half-step" sequences. Diodes D1-D4 prevent sparking at the switch contacts, and actually return the stored inductive energy back to the battery. For example, assume that the cpl switch is closed and a current of 300mA is flowing from the + 1. 5 V battery and through the et> 1 winding to ground. The instant the switch is opened, a current of - 300mA flows through the c/>3 winding via D3. The direction of the current is back towards the battery. The current rapidly drops to zero and the stored energy is returned to the power supply. During this period, the voltage across the open-circuit c/>2 switch is twice the supply voltage (neglecting diode drops). This is something to keep in mind when selecting transistors for unipolar drive circuits. The tables beneath Fig.2 show Below: this simple unit can be used to demonstrate all the characteristics of a stepper motor. It uses the circuit shown in Fig.2 , wired up on a piece of perforated board. The stepper motor is a surplus commercial unit. the required button presses to move the stepper motor in a clockwise direction, in either full-step or halfstep modes. Reversing is easy just walk your fingers backwards across the buttons. At this stage it is worth fitting some sort of lever securely to the motor shaft so that you can check out the torque characteristics. Notice that the holding torque is much greater than the " working torque" (the torque developed when moving on to the next phase). Most stepper motors will develop an impressive torque with only 1.5V applied to the windings. The maximum rated continuous DC voltage is usually only 5V. Why then do some drive circuits use 50V supplies? The answer has to do with speed. Try this simple experiment: leave the pushbuttons open circuit, and turn the motor shaft briskly using the attached lever. At around 60 RPM you will feel a distinct drag and the ammeter will show around half an amp being fed back into the battery. The speed at which the current just starts to flow backwards is the speed it would run at when driven as a motor from the 1.5V supply. In this respect, the mot or and drive combination AUG UST 1989 15 An introduction to stepper motors - ctd OPTIONAL AMMETER 0.5A-0-0.5A +1.5V 0 CELL + 1.5V - D3 ,j,1 <1>2 ,j,3 J,4 ,j,1 q,2 <1>3 <1>4 ON - - - ONON-- , ON - - ON - - - ON ON - - - - - ON ON ON ON - ON ON ON ON - - ON - ON - ON ON ON - ON FULL STEPS TWO WINDINGS ENERGISED FULL STEPS ONE WINDING ENERGISED ON ON - - ON - HALF STEP SEQUENCE Fig.2: this simple demonstration circuit will allow you to take almost any stepper motor for a "test drive". In addition to the stepper motor, it uses just four pushbutton switches, four diodes, a meter and a 1.5V battery. The accompanying tables show the step sequences. - - - - - - - + V MOTOR R- +V LOGIC STEP INPUT DRIVE LOGIC DIRECTION INPUT -;- .,. Fig.3: a typical stepper motor drive circuit. The NPN transistors and their associated clamp diodes are usually incorporated in a "power-pack" IC, along with the necessary logic to generate a 4-phase drive sequence from a series of input "step" pulses. 16 SILICON CHI P behave exactly the same as any normal DC motor. To go faster, you need a higher voltage. Of course, you will also need some means of preventing the motor from burning out when it is standing still. The stalled current is usually limited by two resistors (R) as shown in Fig.3. Only two resistors are needed for 4 phases, because cpl and cp3 are never both on at the same time; neither are cp2 and cp4. Fig.3 is the most commonly used drive circuit for low to medium power motors. The VcE rating of the NPN transistors should be greater than twice the motor supply voltage. High-power motors require a different approach. Dropping resistors would waste too much power, so the driver transistors are used as switching current regulators instead. Shaft torque There are numerous applications for stepper motors. In models, for example, a gearbox is often unnecessary because of the high shaft torque. And don't forget their braking ability. Try this experiment. Remove the 1.5V cell from its holder and depress all four pushbuttons. Now try to turn the motor shaft. The damping effect with all windings shorted is amazing. The braking torque saturates at only a few RPM. A constant current load circuit would enable the stepper motor to be used as an adjustable brake on reel-to-reel tape hubs. Put the 1.5V cell back in its holder and try turning the motor really fast. You will notice that it feels like a slipping clutch. This is because the generated AC current is limited by the winding inductance as the frequency increases. This constant current generating characteristic is very useful for bicycle lighting systems - just choose the total bulb wattage to suit the saturation current of the " alternator" , and the bulb brightness remains constant above a certain threshold speed. 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The trouble is, all the really collectible equipment from the 1920s era is now in someone else's collection. However, there is another way. Looking at things realistically, it is unlikely that I will ever get hold of the original Hertz spark transmitter and receiver, even if it does still exist. Alternatively, I could build myself a replica if I so desired. Having a replica is perhaps better than having nothing at all. Replicas are big business in the firearm industry and one can buy at fairly reasonable prices almost any old gun that has been made in the last 150 years. Frontier Colts, cap and ball pistols and muzzle loading Enfield rifles are particularly popular. Replica radios In recent years, nostalgic replica radios have appeared in shop windows (and will most likely stay there). These radios can be bought for around $80 and are transistorised AM, FM receivers with miserable little 75 millimetre loud~ speakers. The cabinets look nothing like they should and the general ef- ,. ,/ , ... ,. . r ~ -~- This is the original 1920s-style cabinet into which the new receiver was built. A brass plate under lid reads: "Supplied by D. W. Reddan, 183 Smith Street, Fitzroy. Receiver type C". It would have been made in about 1925. 18 SILICON CHIP feet is far from realistic. In fact, these modern "replicas" have no real resemblance to the valve sets they are supposed to emulate. Unlike replica firearms (which are perfect in almost every detail), replica radios offer the collector absolutely nothing! But perhaps one shouldn't snub replica radios too much because the real thing is becoming increasingly difficult to find. Receivers from the 1920s era are just about entirely in the hands of collectors and if an early set is found in someone's shed, it will generally be in such poor condition that it may not be of much use. I recently found a derelict mid-1920s 3-valve radio that was in a really sad state of repair. As far as I was concerned, the solid timber cabinet with its hinged top was about the only useful part. The dials on the front panel were smashed and the circuit board had been altered so many times that it was impossible to tell what was original and what was not. It looked as though at least a dozen experimenters had tried to get the set working again with none of them succeeding in their task. Regardless of the old set's state of disrepair, I swooped on it like a hungry vulture. Although it was pointless to try to repair the original receiver, I could see great possibilities in it for a complete rebuild job. What I had in mind was to use the cabinet and its front panel and build a completely new circuit on a new baseboard. The original plan (complete with the necessary bits and pieces) was to build a receiver with a stage of radio frequency amplification in- coni triodes which were perhaps a bit modern for a mid-1920s replica. Either 4V or 6V valves would have been a little more appropriate. However, as the valves and the base board type valve sockets were already on hand, they seemed the logical choice. As few people have any idea as to what a 1920s radio receiver looks like inside, I'm not going to let the 2V valves worry me. While my replica radio won't fool everyone, it is bound to fool most - especially if I don't disclose any of the details. Component details The original circuit board had seen better days. It was scrapped and a completely new circuit constructed on black acrylic sheet instead of the more traditional (and more expensive} Bakelite. The valves used in the new receiver were 2V Marconi triodes, although 4V or 6V valves would have been a little more appropriate. The valve on the left is a power output type. corporating two matching single gang tuning capacitors and two matching tuning dials. This project would have been possible but only with great difficulty. The space on the front panel and particularly inside the cabinet was really too small for such a receiver. After considerable deliberation I settled for a more standard type of 3-valve receiver for the mid 1920s: a detector with two stages of transformer coupled audio. Such a set would naturally have battery powered triode valves in it which should drive a horn speaker at reasonable volume on local stations. Interstate listening may be a bit feeble but headphones .should solve that problem if one really wants to persevere. Regarding the headphone aspect, the set was designed with two audio outlets; one on the front panel for headphones and the other on the main circuit board terminal strip for the speaker. The valves used were 2-volt Mar- The rebuilt set ended up really looking the part. This is mainly due to the fact that vintage components have been used in the circuit. These included hard to get items such as a gridleak capacitor with built in clips to hold the gridleak resistor. The gridleak resistor itself is open circuit, so a substitute 2MO 1W resistor is wired in underneath and out of sight. In addition, two of the fixed capacitors have been doctored by fitting smaller modern types inside them. The tuning capacitor is the set's original and has been scrubbed up with metal polish to highlight its brass and aluminium construction. A small lOOpF variable capacitor from another old radio receiver serves as the reaction control. Two audio transformers of the same make and condition would have been nice but I had to settle for a Philips and an Emmco. I also had to use a 200 filament rheostat instead of the usual 60 type. The final non-standard feature is the circuit base board which is black acrylic sheet and not the traditional Bakelite. Large sheets of black Bakelite are not only expensive but also hard to find. Improvisation Improvisation is the name of the game. Ancient radio components of 1920's vintage are almost unprocurable and one simply has to make do with whatever is available. If it looks something like the bit required, use it! The horn speaker that accompanies this set is also a hybrid and consists of a Brown driver with a AUGUST 1989 19 The unit works well despite being a collection of miscellaneous bits and pieces. Several of the components have even been doctored by fitting smaller modern components inside them. fancy horn of some unknown make sitting on top. Because the rest of the set is a really a phony, it is only appropriate to continue the hoax by coupling it to a mis-matched horn speaker. Although my vintage rebuild is nothing more than a lot of odd bits, the damn thing works despite the fact that no two components came from the same radio. It's like Frankenstein's Monster - created from miscellaneous bits and pieces. The analogy is such that I refer to the set affectionately as "Frank". As mentioned earlier, finding 1920s radio receivers in good condition is fast becoming an impossi- ble task. The vintage rebuild technique is one way of obtaining a reasonable vintage radio that looks the part to some extent. That must be better than just having an empty cabinet or an unrealistic reproduction. Only a close examination of Frank would reveal his true ancestory and very few people would be able to tell the difference. Frank is only a phony in my eyes because I know his shameful past. Sound quality In actual fact, my creation did not work that well at first. Although volume levels were as expected This view shows the new front panel layout, complete with dial knobs, rheostat and headphone jack. Improvisation is the name of the game when restoring receivers from the 1920s, as many of the parts are now no longer obtainable. 20 SILICON CHIP from a 3-valve battery receiver, fidelity was pretty poor to say the least. Sound quality is often lacking in vintage radios. Indeed most of the early sets are harsh, toneless and hard to listen to. The literature from the 1920s often refers to differences of opinion regarding the pros and cons of transformer coupled audio stages compared to resistor-capacitor coupling. The usual conclusion was that transformer coupling gave high gain and poor fidelity, while resistorcapacitor coupling gave less gain but better fidelity. In fact, it's a bit of a laugh to even mention the word fidelity when discussing the tonal aspects of horn speakers. Believe me, the sound reproduction of horn speakers varies from poor to terrible. In Frank's case, the sound was terrible and I decided to do something about it. The first step was an experimental bypass of the audio transformers. These were both disconnected and the three valves resistance-capacitor coupled. The end result was worse - fidelity was still terrible but with a little less volume than before. Several checks of the wiring did not reveal any wiring errors and I was at a loss to know what was wrong. I could only guess that the valves I was using were not really suited to the task I was expecting them to perform. The only alternative was to rewire the circuit the way it was originally, using audio transformers to couple the last two valves. At least the set performed a little better that way than it did with the so called improvements. I had tired of all this wiring and rewiring and Frank lay on the work bench for a couple of weeks unattended. This is a good approach to any problem - simply ignore it and it might go away. Well the problem didn't go away but while Frank was laying there in limbo, I was thinking of other things I could do that might help improve the sound quality. I decided to experiment further. In the end, a bit of a juggle with the "C" battery voltage and the detector plate voltage did the trick. In particular, the sound clarity im- Problems? ... and you don't have our .120page catalogue . .. Close-up view of the front panel. The tuning capacitor on the left is the only original component used in the rebuilt set. A smaller lOOpF variable capacitor from another old receiver serves as the reaction control. At last . .. a TRADE catalogue for the consumer Old radio components are invaluable when it comes to projects such as the one described in this article. This miscellaneous collection includes dials, knobs, valve sockets, rheostats, tuning capacitors and an audio transformer. Restoring these items is a time-consuming job. proved greatly when the "C" battery voltage was reduced from 4.5 to 3.0 volts. At this stage of the proceedings the set was installed in its box and placed on a shelf. It will stay there until I can find time to restore the cabinet. Vintage cravings When I first started collecting old radios I craved for some of the early sets from the mid-1920s era. Now that I have a few of these sets (plus Frank), I can only say how disappointing they are from a listener's point of view. Listening to radio programs using ancient receivers and horn speakers is not particularly pleasant or enjoyable. A novelty yes - but that's as far as it goes. My excursion into 1920s listening has made me appreciate all the more those nice old superhets from the 1930s era. It is my opinion that this generation of receivers is equally as collectible and far more listena ble than those ancient receivers from the previous decade. ~ ARISTA ... your one-stop problem solver. Video plugs and sockets . . . Video extension speakers ... Video flyleads . .. Video RF interference filters . . . Video splitters .. . Indoor antennas . . . Video switching units . . . Down converters . . . Video speaker controllers . . . Video camera lights .. . Video tape rewinders . .. Video cine adaptors ... Video head cleaners ... Video splicing kits . . . Video storage cases . . . Video dust covers . . . Video leads ... Scart plug leads . . . Video dubbing kits . .. Video headphones . . . Video shotgun and wireless microphone systems . . . Pre-amplifiers with video inputs .. . Video camera stands ... Just about anything you want. ... Try us ... NOW! Get your catalogue FREE from your local ARISTA dealer or send $2.50 P&H and your return address to: ARISTI\. ELECTRONICS PTY LTD PO BOX 191, LIDCOMBE, NSW 2141 AUGUST 1989 21 ADCOLA 240 VOLT IRONS 20watt $32.95 SAVE $4eat. TS-1492 30wau$32.95 SAVE $7 Cat.TS-1494 CORDLESS TELEPHONE BARGAIN ONLY $159 DISK DRIVE BARGAIN Brand new Chin on model F2-502 5 1/4' 360k - made in Japan normally $279. Brand new - 3 month warranty. Cat. XD-4600 $149 VIFA 3 WAY SA-130 SPEAKER KIT Cat. PS-0672 1/2 PRICE t 'A lUOUS \VU-40 Combines the functions of light lubricant, penetrating oil, rusl preventative, moisture repellent, PCH TElllUINAL metal cleaner, silicone spray and even household cleaner. • Starts moist engines • Removes tar • Loosens nuts • lubricates loc • Cleans tools • Stops squeaks 150J NA-101 5 ~.~J.95 3ll(·y NA-101 6 $5.50 STRIP BARGAIN 2010 Mklla STEREO EQUALISER (1 octave) This is the famous Jaycar 2010 one control per octave equaliser. This kit would look great with any Hi Fi system and performs beautifully. For full details see page 6 1989 catalogue. Cat. KJ-6535 ONLY $125 ~~ These are high qualrty 10-way thermoplast ~ PCB terminal strip. A used extensively in the alarm industry. Unrts am supplied unassembled, i.e. you have to saew the srews in! These are normally $4.95 Cat. HM-3205 [f<at>OO W<at>(UJ [f[FJ<at>~ cJJ~W©~OO ~QJE©uOO<at>~~©~ 6264 STATIC RAM VERBATIM DISKS AT ~!~~~~! AL1Y~22 . ~~~e~!~ic~~i~~ES NOW $15 . 10+$12•50 88 -8 0 • • Ca.t ll. 44 ~ , your normal supplier. Description 1-9 Boxes 3.5'1S/20 Cat XC-4720 3.5' 2S/2D Cat XC-4721 3.5' 2S/HD Cat XC-4722 5.25' 1S/20 Cat XC-4725 5.25' 2S/2D Cat XC-4726 5.25' 2S/HD Cat XC-4727 4.5 DIGIT DMM FOR $99 CRAZY?! \\'AS $179 10. Boxes . $39.95 $37.95 $46.95 $43.95 DRILL MADNESS *I Are you sick of paying high prices for mini PCB drill bits? We were. Now you don't have to pay outrageous prices anymore. R Brown 2443. Jaycar's direct imports save vou money. DRILi, PACK TOTAL 10 DRILLS FOR ONLY $12.95 Cat T0-2400 - WERE SELLING FOR $24 MINI DRII~LS IN PK'l'S OF 10 * $99.00 $89.00 $22.00 $21.00 ANY PACK ONLY $9.95 $24.00 LO\VER PIUCES ON SINGl ,E IIUYS $26.00 i . Includes all those common ones. , • 1 x 3.5mm - for PC supports, relays • 2 x 1.2mm - for PC pins, hookup wire ' • 3 x 1mm - for resis tors, capacitors etc • 4 x 0.8mm - IC's etc. · · · • 0.8mm x 10 (Cat TD-2420) • 1mm x 10 (Cat T0-2421) • 1.2mm x 10 (Cat T0-2420) • 0.8mm Cat T0-2408 SAVE 70~ • 1mm Cat T0-2410 SAVE 90~ / $41.00 $39.95 • 1.2mm Cat T0-2412 SAVE90~ ~1!1!11!1!~~11!!1!11!~~1!11!1!!11!!1111--I ANY ONE ONLY $1.50 MIXED SEMICONDUCTOR PACK WORK SKILL OLYMPICS Limited Quantity Cat OM-1550 • 10 amp • Digital hold • Trans tester See page 38 19fl9 catalogue nd new pack just finished. Guaranteed minimum 100 units lied but packs generally exceed this amoun 7250. ' IUIDllANGE & TIVEETER LEVEi~ CONTROL BAllGAIN '80 watts handling. See catalogue for full details. Horizontal mounting Cat AC-1684 Vertical mounting Cat AC-1685 SPECIAL CAT PRICE $9.95 N . , Each year the best of Austral ia's young skilled workers battle the best from the rest of the world. The first team of young Aussie's competed in Austria in 1983 at the 27th Skill Olympics. Our 12 "pioneer' competrtors laid a solid foundation - no medals but 10th posrtion in the overall placings. 2 years later in Japan the 18 strong team came home with 6 medals and an equal 5th placing with Austria. Last year at the 29th Skill O~mpics held in Sydney the Australian team won 12 medals and came in thed place behind Korea and Taiwan; causing qurte a stir among the participating 19 nations. Australia is represented in the Consumer Electronics section by a young man named DAVID lAMMIT from Sydney. Jaycar is proud to have helped David with his training and we wish him luck in Birmingham !England) in August 6" T\VINCONE wmERANGE JAYCAR SOLDERING IRON • BUY A S PAllE • Another direct import which saves you monev. GHill 4051 240 volt Stainless steel barrel. 30 watts. Cat TS-1450 WAS $18.95 NOW $13.95 SAVE $5 SAVE $2 Cat CE-2320 ONLY $14.95 =-_ \--•;;re:-..· _;• ,q 37D PLUG BARGAIN (37 way Cannon type D male) Scoop purchase. AJ Harvey 2444. PC board mount, straight pins. Cat PP-0861 For a short time only I Sound familiar? 5mm Pkt of 20 Cat HP-1104 , 1r AM/l'M STEllEO 1'UNEll KIT SAU~ Ref: EA Dec 85 - Feb 86 Full details page 5 1989 catalogue $5 for 10 or Cat KA-1636 $1.90 $30 for 100 1!1/hnnnh))i!, SAVE $70 - - -s· A·L·v·A-GE _ S_O_ M_E_C_A_S_H___~.NNE ~l!!!l!!!ll ?R !l!lllll!E~?A ~'~R~ - - - - - - . $ 5 2 9 Turn your surplus stock into cash Jaycar will purchase your )(EA D PJ( 0 NES ,. • CALtatRvm JOHNSTON or With 6.5mm adaptor BRUCE ROUTLEY TODAY ONLy $5.95 SAVE$:r 00 (02) 74 7 2022 Cat AA-2014 WIRE STRIPPER, CUTTER & PLIERS See cat page 119 SAVE $2 $5.95 A E b r2 3 styles available 1. BLACK 4mm high Cat NL-4100 2. SILVER 7mm high C NL-4104 ~ ~ 3. FLOUAESCENT YELLOW Cat NL-4106 ~ See page 85 of catalogue L!?.) I Remote Control Cat KA-1636 $70 • SAVE $29.95 EXfflE RECIIA.RGEABl.,E BATTERY MONITOR MADNESS MADNESS........ . Another distress stock purchase! This time a quantity of Samsung brand 12" composite computer monitors. Available in either green ,EXPENSIVE RECOMBINATION ELECTRODE TYPE Another surplus buy which saves you a fortune. This time we have 12 volt Gel-type batteries. They are high-tech recombination electrolyte batteries (a spin off of the space program) which can be used in any orientation and which do not gas, spill. leak or need top up. We are able to offer these batteries at about 1/2 trade price. These are not "cheap" batteries, they are high quality and are made in Japan. PLEASE NOTE - TRADE NOT SUPPLIED. SAVE HEAPS THREE SIZES AVAILABLE 1.9 amp/hour Exide No. RE 12-1 .9 ONLY $14.95 10+$13.95ea 2.6 amp/hour Exide No. RE 12-2.6 Cat. SB-2482 (Trade price $30) ONLY $19.95 10+$18.95ea 15 amp/hour Exide No. RE 12-15 Cat. SB-2484 (Trade price $35) ONLY $79 Cat. SB-2490 10+$75ea SPECIFICATIONS + + + • (1.9) specs for 1.9 A/H bait • (2.6) specs for 2.6 A/H batt • (15) specs for 15 A/H batt Nominated Capacity (A.h.) 20hr rate to 1.75 V.P.C. 1.9, 2.6, 15 .. 10hr rate to 1.75 V.P.C. 1.8 (1.9 A/H). 2.4 (2 6 A/H). 14 (15 A/H) "''"' 1.6(19), 2.2(26), 128(15) 5hr rate to 1.7 V.P.C. 1.1 (19), 1.6 (26), 9 (15) 1hr rate to 1.6 V.P.C. Maximum Discharge Amps 40 (1.9), 40 (26), 100 (15) <at> Standard terminals Short Period 75 (1.9), 100 (2.6), 400 (15) /f·· '"'• .. Charge Rates 3.75 (15) Standby & Cyclic Use - max amps 13.5-13.8 (15) Standby Use - volts 14.4-15 (15) Cyclic Use Energy Density (Wh/1) Specific Energy (Wh/Kg) Internal Resistance Fully Charged (milliohms) Weight (Kg) Size 0.5 (1.9). 0.6 (2.6) 13.5-13.8(19), 13.5-13.8(26) 144-150(19). 144-15.0(26) 61 (1.9). 58 (26) , 25 (1 9), 28 (26) :~ .,,,,, ' ff· 1oop91.so1261.151151 ''{_ .• )r 09(19), 1.1 (26),59(15) , .. . ,,:?:,:/ 178mm x 34 x 67 LWH inc connector (1.9) 134mm x 67 x 67 LWH inc connector (26) 181 mm x 76 x 167 LWH inc connector (15) Mail order customers in WA and NT please add on extra $2 for 1.9 and 2.6 batteries for extra mail charges due to weight, and $10 extra for 15A. l!lP.:I ~~B.11;,;n AIGti.,., ..:!.~ ........ _. , ,..,.~) ..... ~~ HH1'0(Y1[ Ullf~T 'DIGITAL HVGRO-THERMOMETER Measures temperature AND humidity at the same time! This compact battery operated unit has two bright LCD readouts. One for temperature (down to -25°C) and the other for humidity (20 - 95%) Can be used in the car or home/office etc. DIJE MID JULY Cat QM-7230 $69.50 or amber. Specifications Picture Tube Mode Composite Input Signal ■ Polarity ■ Level ■ Impedance Active Video Period ■ Horizontal ■ Vertical ■ Video Band Width Scanning Frequency ■ Horizontal ■ Vertical Active Display Area Display Characters Input Connector Controls ■ Front ■ Rear ■ Internal 12ZBY31N (12" diagonal 90° deflection) Composite Negative sync 0.5-2.0V pp 750 39.11 )JS max. 12.21 ms max. 25MHz (-3d8) 15.75kHz 60Hz 216(H) x 160(V) 40 characters x 24 lines (7 x 9 cell) RCA Phono Jack $99.50 SAVE $50 LIMITED STOCK - BE GUICK GREEN Cat XC-3000 AMBER Cat XC-3001 WORLD TIME This product is ideal for overseas travellers or those who ring overseas, and have trouble sorting out time differences. It is pre-programmed with 12 times* for different cities including Tokyo, Hong Kong, Bangkok. Sydney, London. Paris . Cairo. Moscow, Honolulu, Los Angeles. Chicago, New York and one spare zone for another city. The times are displayed immediately after touching the button. Also incorporated is a calculator as well as the date and an alarm. All this fits into a credit card size unit 3mm thick. Another direct import that saves you money. .*Once one time zone is programmed in. the other zones are automatically calculated by the unit. Cat.OM-7210 /-, /-, /-, /-, /-, "v--) "v--) ~ ~ ~ ONLY $19.95 UHF ANTENNAS 91 Element , , ~ , ~ \ ' Receives all band 4 and 5 channels through 21 to 69 Ideal for fringe areas Includes balun for75!lcable Maxgain16dB Cat LT-3182 "'-Y ~~~~--"" $139 · ;-- 43 Element ELECTRONIC PEDOMETER We've all seen those old mechanical pedometers in mail order catalogues that don't work terribly well. Electronics have caught up, and Jaycar proudly present the first electronic pedometer FEATURES • Measures distance travelled in miles and kilometres. • Counts steps taken • Tally counter. to count numoors by hand • Calculator function Easy to read LCD display, clips on belt, battery lasts for years. Size 50x56x17mm Direct import Cat. QM-7220 $29.95 ONLY Power on/off, contrast V-hold, V-size. Brightness V linearity, H hold, H linearity, H width. Focus Mechanical and Environmental ■ Operating Ambient Temperature +5° through +40°C ■ Power Supply 115V, 230V/60Hz, 50Hz ■ Power Consumption SOW max ■ External Dimensions 312(W) x 300(H) x 307(D)mm ■ Weight Approx 7.5kg. '---------' ■ Suits both bands 4 and 5 Ideal for medium signal reception areas Includes balun ;•i;~dB • 11 Element ·-",. _ The baby Again bands 4 and 5 Includes balun BdB gam ,. · •. Cat. LT-3178 $39.95 EASY TO INSTALL Simp~ mount above or below your existing VHF aerial and connect to existing cable with a diplexer. Cat LT-3014$12.95 - AUTOMATIC CHARGER FOR NiCads NiCad DISCHARGER Ref: EA August 1989 Combine this automatic discharger with our equally automatic charger kit (KA-1718 $42.50) and rejuvenate your Ni Cad batteries. It's amazing how they'll respond to the discharge/charge treatment you could add years to the life of your re-chargeables. Kit includes PCB, box, front panel and all specified components. Power supplied by Ref: EA July 1989 This kit is a fully automatic NiCad charger that is simpe and cheap to build . Once the battery is charged, the unit automatically switches td trickle charge. Kit includes PCB, box, panel and all specified components. Power supply extra Cat. MP-3020 $14.95 iJ~J:t;' NEV' l{\1S ~-· '•' TIME {hvure) 8ATTEAY ~ Lf:CT •• Po~OH Ch"!'filll ; Trlllll lo , 8M1cry' A"!, CI\Ullf: IIV AM . AA AA C &0 100mAh 180mAh ·soo,11AII 6 DllmAh ll)mA IDmA so,,.A, 60m.l .1.2Atl 120mA . 1 2 3 4 Cat. KA-1718 $42.50 S STEllEO 1/'2 OCTAVE GRAPIDC Ref Silicon Chip August 1989 EQUALISER TOUCH LAMP DIMMER This project enables you to equalise your room or disc or other source etc. , with great precision. Until recently you had to buy TWO mono equalisers to do this task. The Silicon Chip people have come up with a state-of-the-art design featuring close tolerance capacitors and superior gyrator performance. Headroom is over 100d8. Distortion? Negligible <0.001 %. With TWO controls per octave you have a precision Hi Fi instrument that covers 28Hz to 20kHz. 20 slider controls per channel with Eq. out for dubbing tape. ±12d8 per control. 240V powered. 19· 2 unit rack configuration. The Jaycar kit is complete down to the last nut and screw. Cat. KC-5055 PRICE TO BE ADVISED REMOTE FOR TOUCH LAMP DIMMER Ref: Silicon Chip June 1989 Amaze your friends. Replace your normal light switches with these. All you see is a plate. To dim simply hold your finger on the plate. To switch simply touch the plate. Works extremely well. $32.95 Cat. KC-5052 Ref: Silicon Chip July 1989 Add one or more extension units, so you can dim/switch your lights from several positions. These can be simply wired in place of 2-way switches. * Cat. KC-5053 $14.95 1/3 OCTAVE EQUALISER KIT• $239 * * * * Cat.KC-5050 RGBI TO PAL ENCODER/MODULATOR Ref: EA August 1989 Here's a kit for a low cost RGBI to PAL video encoder and RF modulator, suitable for use with an IBM or compatible computer fitted with a colour graphics adaptor (CGA). By providing a modulated RF signal on a suitable TV channel, it allows a standard colour TV receiver to be used as a colour monitor for games etc. Kit includes PCB, box, and all specified components except those for optional power supply. $39.95 Cat. KA-1720 Why buy expensive Cand D size Ni Cads when these adaptors allow you to use low cost AA NiCads instead. These adaptors look like a normal battery exept that they are hollow, and on AA NiCad can be inserted inside. These can then be used in place of the C or D Ni Cads. CSize Pktof4 $4,95Cat. SB-2462 D Size Pkt of 4 $4,95 Cat. SB-2464 t• , }1,. AA Ni Cads 500mA/hr $3.50 ea ~ ") • ."" 4 for $12.50 cat. SB-2452 . m'ff,;. STEREO COMPRESSION FOR CD PLAYERS Ref: Silicon Chip March 1989 Simple compressor circuit reduces the dynamic range of CDs so that you can make good recordings. Kit includes PCB, box, and all specified components. (12V AC plugpack not included Cat. MP-3020 $14.95) ~~~~~~~~~~~~~~~~~~~~~~~~~Cat. KC-5051 Quality Disks at Silly Prices Another Jaycar direct import. Would you believe - computer disks with a LIFETIME GUARANTEE for less money than you have ever had to pay before! 51/4' DSDD 48TPI DOUBLE SIDED /DOUBLE DENSITY Cat XC-4730 $6.50 for 10 3 1/'z: MF2DD 135TPI DOUBLE SIDED /DOUBLE DENSITY Cat. XC-4736 $26.95 for 10 5 1/4. DSHD 96TPI DOUBLE SIDED /HIGH DENSITY Cat. XC-4732 $49.50 DMM's Direct import - one hand operation Frequency counter Capacitance meter logic Probe l 10 amp $59.95 20 ranges Diode checker Cat. QM-1410 Cat. QM-1400 $99.95 ~ ' $18.95 for 10 All disks are supplied with envelope, index labels and write-protect tabs. Remember, these disks might be cheap but they are good quality. We are so impressed by the quality we are happy to offer a lifetime guarantee. ~t:tiilt ■r~: SYDNEY - CITY PARRAMATTA CONCORD VISA HURSTVILLE HEAD OFFICE 115 Parramatta Road Concord 2137 Telephone 102) 747 2022 Telex 72293 FACSIMILE 102) 744 0767 MAIL ORDER VIA YOUR 117Yortc St (02)2671614Mon-Fri 8.30 - 5.30 Thurs 8.30 pm - Sat 9 - 12 355 Church St (Cnr. Victoria Rd) (02) 683 3377 Mon-Fri 9 - 5.30 Thur., R.30 pm - Sat 9 - 4pm 115 Parramatta Ad 102) 745 30n - . Mon-Fri 830-530- Sat 8.30- 12 121 Fore.1t Rd (02) 570 7CXXJ Mon-Fri 9 - 5.30 Thurs 8.30 pm - Sat 9 - 12 MAIL ORDERS P.O. Box 185 Concord 2137 H OnlNE 02 747 1888 FOR ORDERS ONLY TOLLFREE (008) 022 888 ff $10 - $24.99 $25-$4999 $50-$99 99 OVER $100 S 3.75 $ 4.50 $ 6_50 $8.00 ROAD FREIGHT ANYWHERE IN AUSTRALIA $13.50 GORE HILL BURANDA QLD MELBOURNE-CITY SPRINGVALE VIC POST & PACKINO 188 Pacific Hwy (Cnr. Bellevue Ave) (02) 439 4799. Mon-Fri 9 - 5.30 Sat 9 - 4pm 144 Logan Rd (07) 393 0777 Mon-Fri 9 - 5.30 Thurs 8.30 - Sat 9 - 12 Sh~ 2. 45 A'Beckett St City (03) 663 2030 Mon-Fri 9 - 5.30 Fri 8.30 - Sat9 -12 887-889 Springvale Road Mulgrave (03) 547 1022 Nr Cnr. Dandenong Road Mon-Fri 9 - 5.30 Fri 8.30 - Sat 9 • 2 Studio series 20-band stereo equaliser This completely new stereo equaliser is intended for home or professional use. It has a performance equal to or better than the finest commercial models but you can build it for a fraction of their price. By LEO SIMPSON & BOB FLYNN Have no doubt about it. This new equaliser has a performance that gives away nothing to the very best commercial equalisers. It has very low residual noise and harmonic distortion - much lower than any previously published design. The new stereo equaliser is a half-octave design, with 20 bands per channel. As a half-octave unit, it is a compromise between the high resolution of a third-octave design, as published in our March and April 1989 issues, and the normal octave band arrangement of a stereo equaliser. Ideally, we would have liked to produce an upgraded stereo ver26 SILICON CHIP sion of our third octave design mentioned above but it just would have been too big and unwieldy - hence the compromise of a 20-band stereo design which still fits into a standard rack mount case. But while the number of bands is a compromise, the performance is not. It rivals the performance of compact disc players. As you can see from the accompanying specification panel, the harmonic distortion is particularly low while the signal to noise ratio is very good - better than - 104dB unweighted with respect to 1V RMS. That is better than many compact disc players. The half octave band frequencies are as follows: 28Hz, 39Hz, 55Hz, 78Hz, 110Hz, 156Hz, 220Hz, 312Hz, 440Hz, 625Hz, 880Hz, 1.25kHz, 1.75kHz, 2.5kHz, 3.5kHz, 5kHz, 7kHz, lOkHz, 14kHz and 20kHz. Adjacent frequencies have a relationship between them which is close to 1.414 [the square root of 2), giving the half octave factor. By contrast, in an octave band equaliser, the bands increase by a factor of 2; eg, 625Hz, 1.25kHz, 2.5kHz, 5kHz and so on. With a half octave equaliser, you have much finer control over the equalisation which is desirable whether you are doing PA work, customising your own tapes or equalising rooms and loudspeakers. Special slider pots So each channel has 20 slider pots. These are the special slider pots which were first featured in our third octave equaliser mentioned above. They are specially imported by Jaycar Electronics. select the equaliser function or pass the signal through completely unmodified. The back panel is completely bare except for a group of 12 RCA phono sockets. Why so many? Two pairs are for the inputs and outputs to your stereo amplifier while another two pairs are to duplicate the Tape Monitor function on your amplifier, as already mentioned. Another pair is for equalised outputs which are always available, regardless of the settings of the front panel buttons. These equalised outputs can be very useful if you want to custom equalise your tapes when dubbing, say for use in your car. The remaining pair of RCA sockets is not used. In the past, graphic equalisers have been designed with linear pots and this has led to a problem whereby the boost and cut for each slider is concentrated at the extremes of travel. In other words, to obtain an audible effect from a particular slider, you had to push it a fair way from the centre detent setting (which gave a flat response) before an audible effect was heard. This is inevitable with linear pots. To solve it, the potentiometer manufacturers in Asia have come up with a new design of resistance element for sliders intended for graphic equaliser use. Called the 4BM taper, it is effectively a centre tapped element with a log/antilog resistance taper; log in one direction of travel, antilog in the other. The new element concentrates more of the boost and cut action in the slider travel immediately either side of the centre detent setting and thereby gives a better control action. Apart from the 40 sliders, there are three switches on the front panel. On the righthand side is the push-on push-off mains switch and above it is the red LED power indicator. On the left hand side are two push-on push off switches. The top one is the Tape Monitor loop. It replaces the Tape Monitor function on your stereo amplifier. This is necessary because normally you would connect the equaliser into the tape monitor loop for convenience of use. That is not to say that you can't connect the equaliser in the signal path between a stereo control unit and power amplifier. However, if you want to use it for equalising tapes when dubbing, it is more convenient if it is in the tape monitor loop. The lower pushbutton switch is a bypass control which allows you to Chassis details Inside, virtually all the wiring is taken care of by three printed circuit boards. There is one long board to accommodate the 40 slider controls and another large board to accommodate the active equaliser circuitry. Finally, a smaller board takes care of the power transformer and power supply circuitry. This latter board is exactly the same as used in the third octave Specifications Frequency Response Equaliser out Equaliser in Boost and cut Flat 1 0Hz-20kHz ±0.5dB; -3dB at 60kHz ±12dB Signal Handling Gain Maximum input and output Unity 8 .5 volts RMS (all controls flat) Harmonic Distortion <.005% for frequency range 1 0Hz to 20kHz; typically better than .001% Separation Between Channels With respect to 1 V RMS - 77dB at 1 0kHz; -95dB at 1 kHz ; -98dB at 100Hz Signal to Noise Ratio With respect to 1 V RMS 1 04dB unweighted (20Hz-20kHz) 1 05dB A-weighted Input Impedance 100kD Output impedance 470D AUGUST 1989 27 10k INPUT~Mf.-......- - - - 1 R2 lk l Vout Fig.1: this circuit demonstrates the basic principle of a graphic equaliser with only one slider control. The tuned LC circuit shunts signal to ground to give either boost or cut. In practical circuits, inductor L is a gyrator. equaliser although some of the filter capacitor values used in the circuit are different. The slider board and the main board are linked together by five short multiway cables with plugs and sockets at each end for easy removal. To ensure that no problems are likely to occur with earth loops, the entire circuit of the equaliser is completely isolated from chassis although the chassis itself is connected to mains earth. Circuit principles The circuit principle used in virtually all of today's graphic equaliser designs is the same. We have already talked about this principle in our previous equaliser articles but for the sake of completeness, we will repeat the description here. Each frequency band requires its own resonant circuit, as shown in Fig.1. This resonant circuit is connected into the negative feedback circuit of an operational amplifier connected in the inverting mode. Fig.1 shows the op amp with just one resonant circuit. A real circuit has a resonant circuit for each frequency band but we show one just to keep things simple. Now consider how it works. With the 5Dk0 slider control in the centre setting, the op amp provides unity gain and the tuned LC circuit has virtually no effect on the frequency response. When the slider pot is set to the boost end, the negative feedback 28 SILICON CHIP Fig.2: the circuit configuration of a gyrator. The op amp transforms capacitor C into an inductor which is proportional to Rt, R2 and C. tends to be shunted to ground by the tuned circuit. Since it is a series tuned circuit it will have a low impedance at its resonant frequency. Hence, the feedback will be reduced at the resonant frequency (and for the narrow band of frequencies on either side of resonance), and so an increase in the gain will result. Thus, the signal will be boosted over a narrow frequency range. When the slider is set to the cut end, the negative feedback is at a maximum and the tuned LC circuit actually tends to shunt the input signal to ground. This results in a le .............. ~ .c--: Fig.3: this diagram shows the relationship between the voltage and current in the gyrator circuit of Fig.2. reduction in gain at the resonant frequency. Naturally, the amount of boost and cut is proportional to the slider setting and reduced settings give reduced amounts of boost and cut. Gyrators instead of inductors Tuned LC circuits mean inductors should be used throughout the circuit; 40 in fact, one for each frequency band, in each channel. But instead of inductors, our circuit follows normal design practice and uses gyrators instead. Fig.2 shows the circuit of a gyrator using an op amp. It effectively transforms a capacitor into an inductor. It does this by altering the phase of the current through the capacitor for a given applied signal voltage. In an inductor, the current lags the voltage (ie, the current is delayed in phase by go 0 ) while in a capacitor, the voltage lags the current (by go 0 ). Consider an AC signal source, Vin, connected to the input of Fig.2. This causes a current to flow through the capacitor and through the associated resistor Rl. The voltage impressed across R1, as a result of the capacitor current le, is fed to the non-inverting input of the op amp which is connected as a voltage follower (with inverting input connected directly to the output). Because it is a voltage follower, the op amp reproduces its input voltage exactly at its output. V0ut then causes a current to flow The new equaliser is easy to build with virtually all the circuitry accommodated on three printed circuit boards. Note the use of the miniature encapsulated 5% tolerance capacitors which not only enable a much smaller printed circuit board but also give improved performance. Plug in wiring connectors take care of most of the wiring between the two main boards. through resistor R2. This current, lout, then adds vectorially with the input current le and the resultant current which flows from the source lags the input voltage. As far as the signal source is concerned then, the gyrator looks like an inductor, not like an op amp with two resistors and a capacitor connected to it. The inductance is given by the formula: L = Rt x R2 x C where L is in Henries, R is in ohms and C is in Farads. To make the tuned LC circuit shown in Fig.t, all we need do is to connect a capacitor in series with the input to Fig.2. Now refer to the main circuit diagram. This shows just one channel of the stereo equaliser which is basically just one gyrator circuit repeated 20 times, with different values for Rt, R2 and C. The key op amp in the circuit is IC2a and it performs the same function as the one in Fig.1. 20 50kQ slider pots are connected in parallel in the feedback network of lC2a and each has an associated The power supply PCB is adjacent to the power switch and delivers regulated ± 15V rails to power the equaliser circuitry. gyrator and additional series capacitor. For example, the gyrator for the 55Hz ½-octave band is IC3c and this is connected to the wiper of the slider via a tµ.F capacitor. Similarly, for the 1.75kHz band (immediately below IC3a on the main AUGUST 1989 29 TAPE PLAYBACK +15V r- LINE ~r-.r. I~ LINE INPUT 11 II 0.47 DUTPUT · 100k EQUALISED TAPE OUTPUT .,. II I -=J!l TO TAPE FIGURES IN BRACKETS INDICATE RIGHT CHANNEL DEVICES. 220pf 50k 50k 0.47 820() 750() 680Q 680() -15V 28Hz 55Hz 39Hz 680() .068 +15V 91k -15V 110Hz 78Hz .,. 50k 50k 620() 50k· 50k 620() 6200 50k 620P. +15V 880Hz 1.25kHz 1.75kHz 62011 .0022 2.5kHz 3.5kHz IC3-1C7: LF347 ONLY LEFT HAND CHANNEL SHOWN. ALTER ICS HAVE SAME NUMBERS IN RIGHT CHANNEL STUDIO SERIES HALF OCTAVE EQUALISER Fig.4: the circuit shows one channel of the new stereo equaliser. Each channel has 20 gyrator circuits connected in parallel into the negative feedback loop of IC2a. ICla functions as an input buffer stage. circuit}, the gyrator is IC5a and it is connected to the wiper of its slider via a .033/.lF capacitor. Apart from the 20 gyrators and their common unity gain feedback amplifier, IC2a, there is only one other op amp, ICla, which func30 SILICON CHIP tions as an input buffer stage with a gain of unity. ICl and IC2 are LM833 low noise dual op amps made by National Semiconductor. IClb and IC2b are not shown on the circuit but they provide the identical circuit func- tions in the other channel. The excellent characteristics of the LM833 (previously featured in the Studio 200 Stereo Control Unit published in the June and July 1988 issues of SILICON CHIP) are a major factor in obtaining the high performance of the circuit. It not only has very low noise and distortion, but can also drive 6000 lines which is S3 01 -04 4x1N4002 OUT 240VAC +15V A + LED1 .,. nh7 1000 25VW CASE + 4, 100 16VW + - - - 220 16VW -15V OUT p. p. 0.33 0.15 0.22 6800 6800 .068 ii'"' + 220 16VW + 4x 100 16VW 10 16VW 4x0.1 "·"' 680!l ii'"" 0.1//.022 .022 0.1 620!l +15V .015 P™ 620!1 .01 110k 156Hz 312Hz 220Hz p. p. .00.. .01 .015 6200 P·· 620!1 .0015 .0022 +15V 440Hz ·""" 620!l P·· .ooaa 620!l 680pf .001 625Hz ff'"" 620!l 680pf 47k 5kHz 7kHz 10kHz 5 ffi IN OUT GND an advantage in this circuit. The other major factor in obtaining the high performance is the use of 5 % metallised plastic capacitors for all the critical audio filter stages. More particularly, except for the very largest values, all the capacitors specified are metallised polycarbonate. These have a better power factor than the more corn- 14kHz 20kHz 5 ffi GND OUT IN mon metallised polyester capacitors, particularly at the higher frequencies, and this is an important factor in the very low distortion figures obtained. All the 5 % metallised plastic capacitors in our prototype were kindly supply by Adilam Electronics Pty Ltd who are the Australian agents for Wima capacitors. Another benefit obtained from specifying 5% capacitors is that the tuned frequency and Q of each gyrator stage is much more precisely defined. In fact, to be really sure of obtaining the correct Q and the specified boost and cut figures at the higher audio frequencies, 5 % polycarbonate capacitors must be used. Some varieties of "greencap" AUGUST 1989 31 PARTS LIST 1 rack mounting case, 483 x 88 x 200mm (from Jaycar) 1 30V 1 50mA centre-tapped transformer (Altronics Cat. M-2855) 1 DPDT 250VAC toggle switch 2 2-pole push on/push off switches with mounting brackets 40 50k0 45mm silder pots with 4BM taper, Jaycar Cat. RP-3914 1 cord-grip grommet 8 1 2mm PC board spacers 8 10mm PC board spacers 8 6mm PC board spacers 8 3mm x 25mm countersunk screws 4 3mm x 1 5mm countersunk screws 4 3mm x 1 5mm roundhead screws 6 3mm x 6mm screws (to mount transformer and RCA socket panel) 24 3mm nuts 1 insulated panel with 1 2 RCA sockets 4 stick-on rubber feet 1 solder lug 8 10-way pin headers 8 1 0-way connector sockets 4 4-way pin headers 4 4-way connector sockets 20 1mm PC pins rated insulated hookup wire (for power switch) Printed Circuit Boards 1 •main equaliser PCB, code SC01103891 , 262 x 150mm 1 power supply PCB, code SC01103892 , 113 x 7 4mm 1 equaliser control PCB, code SC01107892 , 370 x 78mm 1 mains switch shield, made of PCB copper laminate (see text) Semiconductors 10 LF34 7N quad op amps 2 LM833 low noise op amps 1 7 81 5 3-terminal regulator 1 7915 3-terminal regulator 4 1N4004 rectifier diodes 1 5mm red LED Capacitors 1 2200µF 25VW PC electrolytic 1 1 000µF 25VW PC electrolytic 4 220µF 16VW PC electrolytics 8 100µF 16VW PC electrolytics 2 10µF 16VW PC electrolytics 2 2.2µF 50VW bipolar electrolytics 8 0 . 1µF monolithics 4 220pF ceramics Cable 1 3-core mains cord and moulded 3-pin plug 1 800mm length of 8-way rainbow cable 1 1 -metre length of figure-8 shielded audio cable 1 400mm length of 250VAC are quite poor in their high frequency power factor and thus can significantly degrade gyrator performance. The gyrators are all based on LF347 quad FET-input op amps, made by National Semiconductor. It is important that these are used and not the ostensibly equivalent TL074s made by Texas Instruments. Nor should the pin-forpin replacement LM837 be used. This is superficially a quad version of the LM833 but it does not per32 SILICON CHIP Audio Filter Capacitors (5% - see text) 6 1µF MKS2/5/63 polyester 4 0.68µF MKS2/5/63 polyester 4 0.47µF MKC2/5/63 polycarbonate form as well in this circuit as the specified LF347s. Power supply Power for the circuit is provided by a 30V centre-tapped mains transformer feeding a bridge rectifier. The positive supply is filtered by a 2200µF 25VW capacitor while the negative supply has a lOOOµF 25VW capacitor. This produces unregulated supplies of about ± 21 volts which are then fed to 3-terminal regulators to produce 6 0 .33µF MKC2/5/63 polycarbonate 6 0.22µF MKC2/5/63 polycarbonate 4 0 .15µF MKC2/5/63 polycarbonate 6 0.1 µF MKC2/5/63 polycarbonate 6 .068µF MKC2/5/63 polycarbonate 4 .033µF MKC2/5/1 00 polycarbonate 6 .022µF MKC2/5/1 00 polycarbonate 6 .015µF MKC2/5/100 polycarbonate 4 .01 µF MKC2/5/ 100 polycarbonate 6 .0068µF FKC2/5/100 polycarbonate 6 .004 7 µF FKC2/5/ 100 polycarbonate 4 .0033µF FKC2/5/100 polycarbonate 4 .0022µF FKC2/5/100 polycarbonate 2 .0015µF FKC2/5/ 100 polycarbonate 2 .001 µF FKC2 /5/ 100 polycarbonate 4 680pF FKC2/5/ 100 polycarbonate Resistors (¼W , 1 %) 2 1MO 2 51k0 6 1 10k0 2 47k0 8 1OOkO 4 5.6k0 6 91k0 2 8200 6 82k0 2 7500 4 75k0 12 6800 4 68k0 24 6200 2 62k0 2 4700 2 56k0 1 3.3k0 , ½W 5% balanced supply rails of ± 15 volts. The outputs of the regulators are bypassed on the power supply board with lOµF capacitors and on the main circuit board with 220µF , lOOµF and O.lµF capacitors. A light emitting diode in series with a 3.3k0 ½ W resistor across the ± 15V supply rails functions as the power indicator on the front panel. That's all we have space for this month. Next month we'll present the full details of construction. ~ Amcronev PS-400/PSL-2 §lcrown® INTERNATIONAL, INC. WHY DO OVER 25% OF AMERICAN RECORDING STUDIOS USE CROWN?* PS-400 POWER AMPLIFIER PSL-2 STEREO PREAMPLIFIER The AMCRON PS-400 is a powerful single or dual channel power amplifier. Because of its rugged design and construction it is the ideal selection for the professional. AMCRON amplifiers are widely known for their quality construction, high reliability and extensive internal protection. The PS-400 is no exception. It provides protection against all forms of load mismatching, overloading or low frequency signal information being fed to the input, excessive temperature and overloaded power supplies. STEREO OUTPUT POWER: 265 watts per channel minimum continuous power into 4 ohm loads, IHz-20kHz at a rated RMS. 165 watts per channel minimum continuous power into 8 ohm loads, 1Hz-20kHz at a rated RMS total harmonic distortion of 0.05% . MONO OUTPUT POWER: 330 watts minimum continuous power into a 16 ohm load, 1Hz-20kHz at a rated RMS. 530 watts minimum continuous average power into an 8 ohm load, 1Hz-20kHz at a rated total harmonic distortion of 0.05%. FREQUENCY RESPONSE: ±0.15dB, DC-20kHz at I watt into 16 ohms; ± !dB, DC-60kHz at I watt into 16 ohms. lkHz Power: 360 watts continuous average power into 16 ohms; 0.1 o/o total harmonic distortion. HARMONIC DISTORTION: Less than 0.001 o/o from 20Hz-400Hz and increasing linearly to 0.05% at 20kHz at 330 watts into I 6 ohms. J.M. DISTORTION: Less than 0.05% from 0.01 watts to 0.25 watts and less than 0.01 o/o from 0.25 watts to 330 watts into 16 ohms, per channel. SLEW RATE: 32 volts per microsecond. DAMPING FACTOR: Greater than 400, DC-400Hz into 16 ohms. OUTPUT IMPEDANCE: Less than 15 milliohms in series with less than 6 microhenries. LOAD IMPEDANCE: rated for 8 and 16 ohm usage; safely drives any load including completely reactive loads. INPUT SENSITIVITY: 1.76 volts for 330 watts into 16 ohms. DIMENSIONS: 19-inch standard rack mount, 7-inches high, 10.125 inches deep from mounting surface of front panel. WEIGHT: Approximately 55 pounds (24.9kg) net weight. This versatile control unit provides comprehensive input and output facilities , using carefully designed circuitry which results in ultra low harmonic and intermodulation distortion. FREQUENCY RESPONSE: Tape, Tuner, CD and Aux ±0.25dB from 10Hz-50kHz; Phono ±0.25dB of RIAA curve from 20Hz-20kHz. PHASE RESPONSE: Tape, Tuner, CD and Aux ± 12° from 20Hz-20kHz; Phono + 14°/ -0° from 20Hz-20kHz. HARMONIC DISTORTION: Less than .009% from 20Hz-20kHz maximum at rated output. Less than .0009% at !kHz with !HF load. Phono less than .009% from 20Hz-20kHz. INTERMODULATION DISTORTION: Less than .0025% at rated output; 60Hz and ?kHz 4: I. Phono less than .0025 o/o at rated output. HUM AND NOISE: Tape, Tuner, CD and Aux 97dB below rated output (103dB with A-weighting) from 20Hz-20kHz; Phono 87dB below I0mV input (93dB with A-weighting). LOW FILTER: 1SdB per octave slope, - 32dB at I0Hz. INPUT IMPEDANCE: Tape, Tuner, CD and Aux 25 kilohms; Phono 47 kilohms in parallel with less than 50pF. INPUT SENSITIVITY: 250mY applied to Tape, Tuner, CD or Aux inputs yields full rated output at full gain of 20dB. OUTPUT LEVEL: Main outputs rated at 2.5V. Phono output rated at 2.5V. Tape outputs carry the same level as the output source selected with the Input selector. Monitor output is the same as the Main outputs and is isolated by 22 ohms. LOUDNESS COMPENSATION: Bass compensation matched to ISO curves (Robinson-Dadson) down to 60 phons; tracked to Level (gain) control with active network to eliminate unwanted sub-sonic boost. MUTING: Seven second turn-on delay during which the outputs are shorted to prevent turn-on transients from reaching the speakers. DIMENSIONS: 19-inch standard equipment rack mount, 1.75 inches high and 11.5 inches deep from mounting surface of front panel. Standard handles extend 2.3 inches from mounting surface. WEIGHT: Approximately 11 pounds (5kg) net weight. $1999.oo Distributed by BOSE $1299.oo ® * Billboard survey 1988 11 Muriel Ave, Rydalmere 2116. (008) 02 3367 Toll Free. HIFIREVIEW Amcron PSL-2 preamplifier & PS-400 stereo power amplifier Amcron is a name which is usually associated with professional sound reinforcement rather than domestic hifi equipment so we were very interested to take a look at these two pieces of gear. The PSL-2 is a stereo control unit with everything for the keen audiophile while the PS-400 is a power amplifier built like a tank but which gives a very fine performance. By LEO SIMPSON With such a strong background in the professional sound reinforcement field you can bet on Amcron to produce domestic hifi equipment which is just about bullet proof. The amplifier in particular is built like a battleship. For its part, the stereo control unit offers lots of user facilities and will have plenty of appeal to those who like to dub material to cassettes for subsequent listening on a W alkman or in a car. The Crown PSL-2 is housed in a 34 SILICON CHIP standard one-unit high rack mounting case which means that it measures 483mm wide and 44.5mm high. It is also 333mm deep, including the knobs and rear projections, and it weighs 5kg. Finish of the case is matt black enamel while the knobs and pushbuttons are in natural matt aluminium. Since the front panel is only 44.5mm high, it looks quite busy with 7 knobs, 6 pushbuttons, 7 LED indicators and the headphone jack socket. Tape enthusiasts will be interested in the PSL-2 as it offers full dubbing facilities, from two tape decks. Purists, on the other hand, will favourably note that the bass and treble control stages can be deactivated. A tiny pushbutton between the treble and bass controls is used to "activate" these controls and when you do so an adjacent LED lights. An interesting feature is the use of two red LEDs to indicate overload of the control unit's output stages in each channel. Associated with these is a pair of green LEDs which act as "signal presence indicators". These are particularly handy if you often change your listening set-up swapping speakers and other gear. The LEDs tell you that signal is present even though a bad connection on your part may prevent any sound from coming from the speakers. Another LED tells you whether there is rumble on the record, giving you the option of switching in the low frequency filter. This is a 'fair dinkum' filter too, giving a steep rolloff for frequencies below 33Hz at the rate of lBdB/octave. This is desirable if you have infinite baffle (ie, sealed box) loudspeakers. If these are fed large signals below their low frequency cut-off they can be badly overloaded, particularly if the bass and loudness controls are being used. We liked the mode control, a feature which is often not included on today's stereo equipment, particularly stereo receivers. The control gives stereo and mono modes as well as a "reverse" position - handy if your speakers have been inadvertently swapped or, more rarely, if the channels on the record require reversing. The mute control also provides a mute position . . .:. . handy if you don't want to alter control settings while you answer the phone. Interior details Naturally, we had a look inside the control unit (curiosity always gets the better of us, you see) and found that all the circuitry is housed on one vast printed circuit board which takes up virtually all the chassis space. Interestingly, the printed circuit board is double sided (ie, copper pattern on both sides of the board) with the pattern on the component side acting as a ground plane or shield for the multiple input tracks. We also noted the individual earth tracks in between the input tracks - these have the effect of reducing crosstalk between channels. Close tolerance capacitors and resistors have been used in the preamp equalisation circuits. This is necessary if the RIAA curve is to be closely adhered to. A further refinement is the provision of separate preset pots for precise adjustment of the phono The PS-400 power amplifier is built like a battleship and really delivers the goods. The power transformer would have to be rated for at least lkW while the filter capacitors are computer grade 13,500µF units. preamp output levels - this is a nice touch. There are quite a few unusual features to the internal circuitry of the Amcron PSL-2 control unit, apart from those we have already mentioned such as the overload, rumble and signal presence indicators. The RIAA preamplifier stages are most unusual and consist of a pair of transistors, one NPN and one PNP, driving an op amp. This is quite different from the common arrangement of a low noise differential pair of transistors driving an op amp. The balance control is unusual too. It precedes the high level signal circuitry instead of being in the more usual position in the output stages. The volume control is a 4-gang unit and operates in the feedback loops of two op amps in each channel. All of this goes towards producing a very quiet control unit, at any gain setting. Another very worthwhile feature is the inclusion of signal muting circuitry. A relay provides muting of both channels at both switch-on and switch-off to avoid any thumps from the loudspeakers. This is most important for a control unit used to drive a powerful amplifier. At the rear of the control unit are quite a few pairs of RCA sockets for the various input and output connections, including a ''processor loop". This is handy if you want to use a graphic equaliser or some other signal processor device. We are not keen on the provision of 2-pin AC sockets. It is too easy to get an electric shock when plugging into or removing the small plugs from these outlets. We'd prefer to see these sockets blanked off. PS-400 Now let's have a look at the PS-400 power amplifier. If the PSL-2 control unit is impressive For the hifi enthusiast, the PSL-2 stereo control unit features comprehensive facilities. Its specifications are excellent and it delivers impressive performance when teamed with the PS-400 power amplifier. AUGUST 1989 35 The power amplifier boards mount directly on the big multi-finned heatsinks. Each heatsink carries 10 power transistors to give a rated power output of 165 watts per channel into B!J. power mono operation. Oddly enough, there are no RCA sockets for the amplifier inputs. Instead, there are the barrier terminals already mentioned and a pair of 6.5mm jack sockets. This reflects the amplifier's " professional" heritage but means that you need a pair of adaptor leads to connect it to the control unit. The top and bottom panels of the amplifier are made of perforated steel mesh and this same mesh covers the 10 power transistors on each of the large heatsinks. Removing the screws for the top mesh panel reveals a massive transformer that would have to be rated for at least 1 kilowatt output. Remember that this is an amplifier which is rated for 165 watts per channel so a transformer of this size will just be loafing along. The filter capacitors are big boomers computer grade 13,500µF units rated at 70VDC. Everything about this amplifier has the flavour of . heavy duty engineering. It is rugged and built to take the rigours of professional use. Having said that though, it is designed to give a very fine audio performance. In fact, it is one of the quietest audio amplifiers we have ever measured. Power ratings This is the rear view of the brute. As well as operating in stereo mode, the two channels can also be bridged for high-power mono operation. because of the amount of careful thought that has obviously gone into its design and manufacture, the PS-400 is impressive because of its sheer bulk. It is a brute of an amplifier - large and very heavy, and not at all easy to lift because of its lack of any handles and its sharp edges on the front panel, multifinned heatsinks and so on. There's just no getting away from the fact that it's big and heavy. It is in a 4-unit high rack mounting case, measuring 180mm high, 482mm wide and 298mm deep. Weight is 36 SILICON CHIP 24.9kg (55 pounds). On the front panel there is a pair of level controls, two green LED "signal presence" indicators and two red LED overload indicators. At the rear of the amplifier are the large hea tsinks already mentioned, two pairs of large binding post terminals and two sets of barrier terminals. One set is for input connections while the other, normally shrouded under a steel plate, is for loudspeaker connections. These allow both channels of the amplifier to be bridged for high Rated power output for stereo operation is 165 watts per channel into 80 loads over a bandwidth of 1Hz to 20kHz at a rated harmonic distortion of .05 % . Into 40 loads, the rated power output is 265 watts over the same bandwidth and for the same rated distortion. In bridged mono mono mode, the rated power is 330 watts into 160 loads while into 80 loads the power rises to 530 watts. Both figures apply for a signal bandwidth of 1Hz to 20kHz and a rated distortion of .05%. Incidentally, you may wonder about the bandwidth figure of 1Hz to 20kHz. The 1Hz figure is not a mistake. In fact, for a small signal, the amplifier's bandwidth is quoted from DC [no Hertz at all) to lO0kHz ± ldB. How many amplifiers do you see that are rated down to DC? That is why the matching stereo control unit really needs a rumble the PSL-2 control unit and without going into chapter and verse, we can report that it performs as it should, right on spec. Power figures The circuitry of the PSL-2 stereo control unit is all contained on one large double-sided PC board. The input tracks are separated by earth tracks to reduce crosstalk. filter. Otherwise, with this amplifier, really low frequency signals can be delivered to the speakers at quite high power levels. As a safety feature, the Amcron PS-400 has "Low Frequency Interrupt" . This interrupts the output drive signal if a DC voltage of more than ± 10V is present or if there is a low frequency output of more than 10V RMS at 2Hz or below. Which brings us to the question: why do the makers rate the amplifier for a full power response down to 1Hz? The answer is that the Low Frequency Interrupt feature monitors the output every four seconds. In between each sampling period, the amplifier can deliver its full power. However, the amplifier will deliver its full rated power continuously at any frequency above 10Hz. Silence is golden As we noted above, the PS-400 is one of the quietest around and is particularly quiet for an amplifier intended for professional use. The quoted figure is -112dB unweighted for a noise bandwidth of 20Hz to 20kHz, with respect to 165 watts into 80. Well, we don't have the space to quote the manufacturer's specs for the PSL-2 and PS-400 in detail they are the most complete we have seen for any amplifier and preamplifier. So let us detail the measured performance instead, starting with the preamp unit. The key specs are the frequency response, adherence to the RIAA equalisation curve, total harmonic distortion and signal to noise ratios for phono and line level inputs (eg; CD, tuner, tape). Frequency response at the rated output level of 2.5V for the line level inputs was - 0.25dB down at 20Hz and - 0.5dB at lO0kHz - the proverbial "ruler flat". The phono equalisation was within ± 0.25dB from 20Hz to 20kHz which is pretty good. And harmonic distortion for the line level and phono inputs was very low, typically less than .0015% at the rated output level of 2.5V RMS. Signal to noise ratio for the high level inputs is quoted at - 97dB unweighted. We measured it at - 104dB unweighted (20Hz to 20kHz BW) and - 106dB Aweighted. For the phono inputs, the spec is - 87dB unweighted below lOmV at lkHz and - 93dB with Aweighting. We measured it at - 87.5dB unweighted and 91.2dB A-weighted - pretty close, eh what? In fact, these figures are about as good as any we have seen for signal-to-noise ratios. We did quite a few other tests on The results for the power amplifier could actually make pretty boring reading and are just a matter of checking off the specs as you go down them: power in stereo, for 4-ohm and 8-ohm loads, bridged mono operation etc - yep, yep, yep. Typical total harmonic distortion at 265W into 40 at lkHz is .0015% . We also confirmed the signal to noise ratios. The amplifier is even quieter than the spec figure. We measured it at better than - 115dB unweighted with respect to 165W into 80 and better than - 122dB Aweighted under the same condition. That is a very quiet amplifier. Enough of figures; it all translates to excellent quality sound. We hooked the Amcron PSL-2 and PS-400 up together with a CD player and our standard reference speakers for our listening tests. That is one awesome power combo. Whether it is the really extended bass response, the vastly underrated power transformer, the overall hifi performance or whatever, the Amcron combination seems to deliver a lot more punch than a set-up rated at 165 watts really should. It really does have grunt. And it performs to perfection on the pianissimo as well as the fortissimo. It is definitely one of the quietest, if not the quietest, amplifier set-up we have listened to. With that wrap-up, you have to concede that the Amcron is well worth considering if you are in the market for a new stereo system. Buy an Amcron and you won't have to worry if your loudspeakers are efficient or not. Prices are quite reasonable. The Amcron PSL-2 has a recommended retail price of $1299.00 while the PS-400 power amplifier retails for $1999.00. For further information on Amcron equipment, contact Bose Australia Inc, 11 Muriel Avenue, Rydalmere, NSW 2116. Phone (02) 684 1255. i1t:1 AUGUST 1989 37 The Incredible ATARI ST For Work and Pia ' ■ - , ( I. , I '41 ' • I 8 f. V " .9 - ,._ 1 0 • When you decide on the incredible ATARI ST you're not only getting the world's No1 home computer, but you're giving your family a compl ete video entertainment system, a superb educational tool PLUS a high powered computer for all your serious computing needs. Dollar for dollar, feature for feature, nothing compares with the incredible performance and versatility of the ATARI ST! Speed, superb sound, amazing power (up to an incredible 1Mb memory), standard features that most others call options ... and graphics so good, you won't believe your eyes! Games, educational, business, desktop publishing ... there's literally hundreds of software titles ready to run on your ATARI ST. JUST PLUG IT IN! The ATARI ST plu~s straight into your existing TV and comes with mouse, 720K 3 1/2" disk drive, fast 8MHz clock speed, Centronics port, RS-232 port, joystick port, musical instrument digital interface (MIDI) and .... ATARI 1040 ST With an amazing 1Mb memory plus all the famous ATARI features! Cat X-6005 ATARI 520 ST 512K RAM X-6000 $700 I:f ijIGijrt I'I %j: 1] t a, • $! ; 'fJ!'Ya£ I I Ii I I GREAT RANGE OF COMPUTER ACCESSORIES Quality omp Creative Music System Here's how you keep your work space organised! Superb work desks designed especially for today's computer systems. Everything packs neatly away - printer, computer, monitor, etc, etc - leaving you room to work. Comes packed flat so it's easy to transport and you can assemble it in no time. Finished in quality laminate so it looks great and it's easy to clean. Choose between the standard DESK MODEL (Cat X-3815) or the space saving UPRIGHT MODEL (Cat X-3816). Both are fantastic value! It's astounding! The Creative Music ,:-,;--~-Synthesizer card simply plugs into your IBM PC or compatible and gives .~\\ you 12 channels (Voices) stereo tl.l"' music output and 32 preset \( \\' instruments to choose from. \ Plus, there's a stereo amplifier to drive speakers, headphones or home stereo directly. You can actually define your own instruments, play background music while you work on your computer, create albums of your favourite tunes and play them in any sequence (great for non-stop party And it allows you to utilize the new music) or cor.i pose your own music. Sierra range of software! Cat X-2020 X Prototype Card Anti Star 0 r s1 Now you can fit a 3.5" disk drive to your IBM compatible. These 720K and 1.44Mb disk drives come complete with mounting kit, hardware, manuals, power and 34 pin adaptors, bezels ... the lot. 720K Version. Needs DOS 3.2 or higher. Cat X-2220 $ A must for when installing expansion cards or chanQing memory chips. Stray static charges can destroy chips in an instant. With adJustable velcro fastening, coiled wound lead and high value series resistor for added safety. Eliminates the risk! Cat X-2042 IBM s299 49 1.44Mb Version. Needs DOS3.3 or higher. Cat X-2221 ·b1e 80 86 Motherboard Building your own computer or upgrading the old one? Our new 12MHz motherboard is the way to go for the ultimate computing power. DRAM not included. Just take a look.... • Expandable to 1Mb using 256K chips • Expandable to 4Mb using 1Mb DRAM chips • Keyboard or hardware selectable 8112MHz operation • Six 16-Bit and Two 8-Bit expansion slots. • Selectable for RAM speed - 80 or 100 nanosecond • Selectable from Owait states on read operations (with 80 nanosecond RAM) • Socketed for 80287 Co-processor • Performance - 13. 7 using Norton S.I. • Battery backed real time clock on board • AMI Bias ROM's included • OK RAM supplied Cat X-1002 $299 A veroboard on an XT compatible expansion card. Complete with interrupt and memory addressing circuits already installed to enable easier construction of more advanced project ideas. With comprehensive manual. Cat X-2034 s14 Twin Port Game Card Want to fit two joysticks to your IBM compati ble for faster action when you're playing games with an opponent? Well, here's how you do it. Easy to fit, it gives you two joystick connections. Cat X-2040 s3995 COMPUTER HOTLINE (02) 888 2002 me.. ::J:?Jm Yp to 8 batt1ri1s at one,... Low Cost Low Profile The DSE Charging Cabinet Charges AAA, AA, C, D and 9 Volts in virtually any _ combination That's right up to 8 cells and/or 3 x 9 Volts at one time. Features indicator lights for each cell , reverse polarity protection, mains operation, test meter and more! Cat M-9505 All one price! S2995each Each transformer has two separate secondary windings which can be wired in series or in parallel. They are fitted with round pin terminations and include connectors. 240V AC primary. Cat M-9517 DSE 0144 DSE 2010 Primary: 240V AC Secondary: 28-0-28V Secondary current: 2A Cat M-0144 Massive 18 volts at 14 amps continuous .. ideal for high power rating power supplies, linear amplifiers, etc, etc. Compare our price with what you've had to pay in the past...What a bargain! Ca! M-2010 Suits 13.BV 25A pk supplies ·· s3495 DSE 0150 ti 300VA Primary: 240V Secondary: 47-0-47V <at> 3 Amps 15-0-15V <at> 5 Amps . Terminations: Flying Leads Size: 115 x 95 x 97mm Weight: 4.85kg Cat ~-0150 As used in our VK powermaster kit S6995 s1 79s POWER SUPPLIES .__,,.-11 111~ 9VDC <at>200mA DSE 2155 Primary: 240V, 50Hz Secondary voltage: 6.3, 7.5, 8.5, 9.5, 12 & 15V Secondary current: 1 amp Terminations: Flying leads Shipping weight: 491g 0 mm NO. CS2078N Cat M-21 55 '6995 NiCad Charger Most devices these days al low for an external charger to be plugged in to charge NiCads (usually a 2.5mm socket). This charger is ideal for all NiCad packs from 6 to 10 cells (ie 7.2 to 12 volts). Fully approved by Electricity Authority. PL 12/20VA 2 x 6V <at>1.7A - 6V<at>3.4A - 12V<at>1.7A M-3596 PL 15/20VA 2 x 7.5<at>1.3A - 7.5V<at>2.6A 15<at>1 .3AM-3597 PL 18/20VA 2 x 9V<at>1.1A - 9V<at>2.2A -18V<at>1 .1A M-3598 PL 24/20VA 2 x 12V<at>.85A · 12V<at>1 .7A 24V<at>.85AM-3599 PL 40/20VA 2 x 20V<at>.51A- 20V<at>1A - 40V<at> .51A M-3601 Cat"M-9526 s179s ~~tt~1 t~¥~6~rT~~ ii~t DSE 2851 s795 DSE 2840 Primary: 240V, 50Hz Secondary voltage : 4.5-0-4.5V Secondary current: 150mA · ~ Terminations: Flying lead "'"'" 1.%"Cat M-2840 DSE 2000 Primary: 240, AC Seconday: 18 volts <at> 6A Terminations: Flying leads~ Cat M-2000 s3&95 s395 > · - -- . DSE 1990 . ~ DSE 1602 - . Primary: 240V Secondary voltage : 18V ~ Secondary current: 2.2A • Terminations: Flying lead Cat M-1990 s1695 = Standard toroidal transformer suited to audio work. Terminations are soldered flying leads and it's supplied with neoprene rubber insulating disks and centering washer. Primary: 240V AC Secondary: 2 x 35V <at> 2.5A 2 x 15V <at> 0.25A Size: 113mm OD x 48mm . ':fi Cat M-1602 :. f t; .. s5995 3-4.5-6-7.5-9-12V <at>300mA For all equipment requiring 9V DC at a 9V transistor type battery or many other static hobby models that require An extremely versatile supply ready for 9V. Eliminator modules simply plugs just about any application. Switchable output gives 6 different voltages into a 240V AC power socket. ranging from 3V to 12V, at up to 300mA. Cat M-9514 3-6-9V DC <at>200mA AC Supply" 16V 900ml The biggest problem with most projects is fitting in the transformer! This one obviates the problem - keep This battery eliminator is one of the the supply components inside, but the most superb buys in this catalogue plug-pack hangs on the power point! many thousands have been purchased With a very healthy 16V at 900mA. It's by people who know how to save perfect for 12 volt DC supplies. Energy money. It is a small plug-in unit that a_ uthoritv approved. , has three output voltages of 3,6 and 9 Cat M-95"67 volts DC at 200 milliamps - possibly the three most used voltages on battery powered equipment. It is ideal for many battery driven items. s149s Cat M-9525 Professional You can install yourself! Vibration Sensor Budget 4-Sector Alarm ...__ _ _ _ __JI/ SIRENS AND HORN SPEAKERS The security system you can install yourself and save monex as well as your valued possessions. It s actually based on a commerical module and comes with a heavy steel case, 4 individually controllable sectors, key-lock switch, inbuilt battery charger for your standby battery, mains power supply, siren oscillator, LED status report .. .the lot! Cat L-5140 Economy lnfrared Detector The all round room protector at a bargain price! With just one or two of these on your alarm system and you can easily protect your entire house. Provides protection for a 6m x 6m area which is .,,,.---.___ ample for most rooms. Features special mounting bracket and swivel head so it can be adjusted for maximum protection. Cat L-5009 s79e5 Electronic Buzzer '2211 It's ideal as a local alarm or warning buzzer! Works between 4 & 15V DC. It's diode protected with 70dB <at> 1m output. Cat L-7009 s199 Piezo Siren Alarm s1495 With a sound output of 11 OdB at 1m this local siren alarm is loud enough to suit most applications. Working voltage 7.5 - 15 /200mA<at> 12V). Frequency 2800Hz. High Sensitivity Volumetric Sensor Cat L-7025 Remarkably small, highly reliable volumetric sensor which gives 120 degree coverage for entrance, room, hallway, etc. Adjustable range up to 12 metres. Complete with tamper protection. Easy to install, it fits virtually any alarm system. (Small enough to protect the Barbie House). Cat L-5013 '139 Mini Two Tone Piezo s7 95 Only 38 x 22mm yet when activated it emits a hI~h pitched, two tone warbling sound that s very attention getting. Operates on 916 volts. Cat L-7027 . Micro Piezo Alarm s1495 Extra Value Security Accessories Great for cars, bikes, vans, etc, especially where space is a consideration. Amazingly compact yet very, very loud. It's easy to install and operates from 12V at 120-240mA. Output is 110dB at 1m. Cat L-7029 Surface Mounting Magnetic Switch Concealed Magnetic Switch In plastic case that makes it much easier to install. Includes magnet, mounting holes and terminal connectors. Cat L-5210 Just the thing for wood doors, windows etc. Can be installed so they're almost impossible to detect. Cat L-5212 This is the same type as used in many commercial car and home alarms. Quite small yet it gives 11 OdB output at 1m. Operates from 12V DC. Comes with adjustable mounting bracket. Cat L-7030 Alarm Horn Cover With Tamper Switch! Siren Speaker s32911 s3e5 Vibration Sensor Detects any vibration or shock caused by forced entry through windows, doors, cabinets, safes, glass surfaces, ceilings, etc. With a adjustable sensitivity and built-in tamper switch. Cat L-5250 s5-e5 $495 They'll find it hard to disable your alarm with this fitted over the horn speaker - and if they try, the alarm will sound. Made from heavy duty steel. Cat L-5300 s24e5 Large Piezo 5 1995 If your alarm hasn't QOt a siren output - here's what you'll need. This speaker horn has the siren driver built into the back of the horn. Just connect the 12V power supply (eg via the alarm's relay output). Cat L-7026 Normal Reed Switches sp Small and easy to conceal. Ideal for doors, windows, etc. Cat L-5215 Panic Switch Great for people who live alone, invalids, etc. Can be used in conjunction with virtually any alarm system. Hit the button and the alarm will sound. Cat L-5285 s3e5 Window Sticker Sticks to the inside of your window or glass doors to tell the crooks they'd better try some place else. Measures 130 x 60mm. Cat L-5311 '2 Large 245 x 270mm heavy gauge aluminium sign in fire-engine red. Cat L-5312 '1095 Reed Switch Magnets •2" To suit the normal Reed Switches L-5215. Cat L-5214 ,, ■ Arlec - Easy Etch Engraver Arlec Supertool You know how easily tools and valuables go for a walk - never to be seen again! Well, here's a great way to identify them. Steel bit lets you engrave metal, plastic, wood etc., with your name or a security number (your driver's licence number is a good one) for positive identification. Comes with 12V plug pack and long cord. wnat versatility! It sands. It polishes. It engraves. It erases. It mills. It's one of the handiest tools you can have in your arsenal! This fantastic hobby machine is a 10,000 RPM power head which does all of the above with the attachments supplied. And because it operates from low voltage (240V plugpack included!) it's safe. Includes the Supertool and plugpack, 2 milling cutters, 1 wire brush, 1 grinding wheel, 4 high speed drills, 5 chuck collets (0 to 4mm), eraser sticks and instructions. Cat T-4753 Cat T-4754 s59ss Rschargsablsl 3-ln-1 Modular Tool It's a DRILL, a SOLDERING IRON and a SCREWDRIVER all in one! This has to be one of the smartest tools for hobbyist, handyman and tradesman alike. Modular components fix to rechargeable battery ~ack (handle) in seconds. Comes with assorted drills, screwdrivers, solder accessories and charger. Cat T-5712 sgg Pocket Soldering Iron Totally portable, butane powered soldering iron that fits easily in the shirt pocket. Provides up to 60 minutes continuous use at full power (equivalent of 60 watts). Temperature control from 10 to 60 watts. Ideal for service people, handymen, technicans, etc. Cat T-1370 The Professional 'Pocket Soldering System The convenient soldering system from Portasol its a complete kit with the equivalent of 10-60 watts of power and temperature adjustment up to 400 degrees Celsius. Ideal for the hobbyist, handyman or technican, this butane powered kit allows you to make repairs, etc. anywhere, anytime. CatT-1374 Electronics/Electrical Formual Casio fx-611 Without doubt one of the most useful tools anyone working with electronics could have. With 27 of the most used electronics formulas built-in - resonance frequency, impedance, · voltage/current gain ... everything! Includes 74 scientific functions, 10 digit display, pro9ramming functions ... its unbelievable. Cat V-3828 s79ss · • El - ... EJ DEIEH:11:3 aamaa mamaam Ull!IEID• Stubby Drivers Medium Du Great for confined spaces - or that tough,.....,.--,,,_u screw which needs extra muscle. You ,.---'"'""" can really get a grip on these! Flat Blade: Cat T-6020 45 Size: L 38mm D 6mm H 45 x 30mm Big enough to get a good strong grip and plenty of leverage. Add this to the rest of the range and you've got the right tool for just about any job.cat T-6050 Blade Size: 150mm x 6.5mm (D: 5mm) Handle: 95 x 25mm $ $1 45 ~ e: ! ~ !d~ a~ i! ?un sometimes! Strong enough for the toughest work ideal for the tradesman. Flat Blade: Cat T-6060 Size L 200mm D7mm H 100 25mm s29s I ,11 · - THE INEXPENSIVE WAY! Teletext Decoder Mkll Kit Form Only The Inexpensive way to get all the advantages of Teletext without taking a third mortgage on the house. You can have access to up-to-date news, weather, sports details, TAB info, subtitles for the hearing impaired (not all programs) and much more. And now, we've made it affordable. Cat K-6360 Just Look... • Comes with Remote Controller • Simply connects to your existing VCR • Includes mains transformer • Comes complete with case and silk screened pre-punched front panel . • Even if you don't have a VCR you can still have Teletext. Just add the Teletext Tuner to your Teletext kit. It can tune to both VHF and UHF channels, fits inside the Teletext Mkll case and enables 6 stations to be pretuned and selected from the IR controller. Cat K-6361 The DSE Variable Ideal for the service man, hobbyist, amateur, student etc. - everyone should have one. Simple to construct. $ Features: • Variable 1.5 Volts to 15 Volts DC • 500mA continuous • Overload protection • No mains wiring required • All necessary parts supplied including plug pack • Pre-punched silk screened front panel • Housed in attractive compact case • No drilling required Cat K-3200 • NSW • Albwy 21 8399 • llankltown Square 707 4888 • Bladdown 671 7722 • Campbelttown (046)27 2199 • Chatlwood Chae 411 1955 • Chullora 642 8922 • Gore Hill 439 531 1 • Goetord 25 0235 • Homsby 477 6633 • HlftMUe5808622• Liverpool6009888• Mailland337866• Mtranda5252722• Newcastkt611896• NorthAyde = =:::=. 88 3855 •Panamatta 689 2188 •Penrith (047)32 3400 •Railway Square 211 3777 •Sydney City 267 9111 •Tamworth 66171 1 • Warringah MIN 905 0441 • Wollongong 28 3800 •ACT• Fphwick 80 4944 •VIC• Ballarat 3 1 5433 • Bendigo 43 0388 • Box Hill 890 0699 • Cotnq (03) 383 4455 • Dandenong 794 9377 • Eat Brighton ;:: :i:: l:s1:::,,·.'t.:;::e:,:o:;3;~7=.:35~~~~1= ::~.M~~~ 3:~1m3•.s~~~i::~~;,~~c~5.f:~2;r.1:.:.= gg~;:~ ;;::~= •NT• Stuart 3 • lunnda 391 6233 •Cairns 3 11 515 •Cherrnlide 359 6255 •Redbank 288 5599 •Rockhamplon 27 964.f • Southport 32 9863 • Toowoomba 38 -4300 • Townavllle 72 5722 • Underwood 341 08« • SA • Adelaide City ~~ 3 1 0800 Park 81 1977 95 - WHEN YOU BUILD IT YOURSELF - YOU SAVE/i "- '_" ._ . # 30 Watt Stereo Amplifier (Short Form) lncmdib/y sasy to build/ Bookshelf Speakers The very latest in the highly successful Playmaster series. A 30/30 watt stereo amplifier that's easy to build, low in cost provides all the essential features and offers excellent performance and superb noise and distortion specifications. Construction is made easy by mounting virtually all parts, including heatsinks, on one large PCB. Short form kit comes with 2 x TDA 1514 IC's, front and rear panels, transformer, PCB and instructions. Cat K-5100 As described in EA 9/88 (CASE TO SUIT CAT H- 24651 $ 99 u tar P actice Amp Module This low cost compact Bookshelf Speaker Kit uses a Magnavox 6MV nominal 15cm driver and a 3AC Tweeter. Buy complete kit and save. Until stocks last! K-4000 - Sleeves, baffles X-overs et~ K-3998 - Speaker Tweeter 3AC $6, 75ea SAVE $6 K-3999 - Speaker Woofer 6MV 8 R $29.75ea SAVE $10 Telee,hone Bell Monitor Ideal for buskers, promising musicians, schools ... anyone needing an easy-to-build, low cost amplifier module. Gives a neat 8 watts which is ample for most situations. Short form kit only, so you can mount it in a case to suit your needs. Cat K-3548 As described in AEM 8/88 126 s2 995 This easy to build kit plugs in parallel with your telephone. When the phone rings, it broadcasts a sequence of tones to a portable FM radio receiver. Cat K-3102 Tilt Alarm Talk about novel: a go-anywhere alarm which will sound when it's titled. Think of the applications: theft alarms for bikes, golf clubs tilting. Cat K-3248 s99s Short Form case not supplied. s199s lfouch Lamp Dimmer Extension For Touch Vehicle Exhaust Monitor lamp This unit can turn your lights on and off or dim them just by touching the decorative plate. Unit is intended for dimming incandescent lamps rated from 25 watts up to a total of 300 watts. Do you have a two-way light switch in your home and would like them replaced with touch dimmers? We have just the thing for your. An extension touch plate is connected in parallel to the K-3001 main unit, so that you can switch your lights on and off or dim them remotely. K-3001 s34 9 ~decr;bed ;, Smcon Chip Cat K-3002 $ This unit can be installed in your vehicle and will detect any carbon monoxide gases which may seep through into the cabin from your vehicles exhaust. Driver will be alerted either by a flashing led or an audible alarm. Cat K-4610 1295 OS XPRESS PHONE AND MAILORDER SERVICE ORDER BY PHONE - 008 22 6610 (NO STD CHARGE) OUTSIDE SYDNEY SYDNEY AND ENQUIRIES - 888 2105 FAX (02) 805 1986 OR WRITE TO OS XPRESS, PO BOX 321 N/RYDE NSW 2113 ALL MAJOR CREDIT CARDS ACCEPTED. O/NITE COURIER AVAILABLE. 24 HOUR DESPATCH OF ALL ORDERS THE CREATIVE MUSIC SYSTEM It's New and it's at Dick Smith Electronics! It's astounding! The Creative Music Synthesizer card simply plugs into your IBM PC or compatible and gives you 12 channels (Voices) stereo music output and 32 preset instruments to choose from. Plus, there's a stereo amplifier to drive speakers, headphones or home stereo directly. You can actually define your own instruments, play background music while you work on your computer, create albums or your favourite tunes and play them in any sequence (great for non-stop party music) or compose your own music. And it allows you to utilize the new Sierra range of software! Cat X-2020 ..... .•. • ]2-VoJce Stereo Music Synthesizer s299 · ALL NEW! COMPUTER PERIPHERALS RS-232 Multilink Adaptor The CASIO fx-611 A complete in-line tester/adaptor which makes complex and time consuming Serial connections a breeze. Comes with 25 pin male and 25 pin female connectors, jumper pads and wires, as well as 24 inline switches, for quick selection for any RS-232 configuration . 8 bicolour LED's tell you at a glance when you've got it right. Cat X-2654 Without doubt one of the most useful tools anyone working with electronics could have! With 27 of the most used electronics/electrical formulas built-in and a programming function which allows you to input your own formula. Includes 74 scientific functions, 10 digit display, programming functions .. . it's unbelievable. Cat V-3828 s49s5 'Voice Master' Sound Input Card Analogue to digital card lets you sample any sound, then view and edit the wave form . If you have 'Speech Thing' the recorded sound can then be played back. Comes with headset and software for experimenting with voice recognition. Set up to 256 different voice activated keyboard macros. Requires an 8-bit expansion slot (XT & $ AT compatible). Cat X-2038 199 'The Speech Thing' Digital Sound Synthesizer Adds sound capability to your PC! It's a full featured 8-bit digital to analogue converter, audio amplifier and software system which is capable of creating almost any sound. Converts text to high quality speech. Just plug it in. Can be used in conjunction with the 'Voicemaster' (X-2038) to sample and edit digital sounds. Cat X-2036 s79s5 . •. El ·~- .. ,, . ...., '"' 0 Daau13 DEIDDD aaaaa l:IDEIDa Copy Images Direct To The Screen! Handy Scanner HANov Now you can copy any image direct to your SCANNER computer screen with the incredible Handy HS-3000 Scanner! 105mm wide, Handy Scanner can be used with Hercules, VGA, EGA or GGA displays. Gives black and white and 3 x 32 quasi-tones. With high 400DPI resolution. Suitable for PC/XT/ AT and compatibles and comes complete with Desktop Publishing Editor. Cat X-3825 The Amazing 3-in-1 Modular Tool At A Price Everyone Can Afford! It Drills! It Solders! It Screws! It's Rechargeable! Cat T-5712 See itat your nearest Only $99 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. 7 Channel switch for DSE UHF converter Here is a simple modification to the Dick Smith Electronics UHF Converter to make changing channels easier. As originally described, this project used a single multi-turn trimpot to adjust the tuning voltage of a varicap tuner. A problem arises when there is more than one station broadcasting on UHF as the trimpot has to be retuned to select each new channel. By adding another four trimpots and a 5-way switch, station selection can be greatly simplified. The steps are as follows: • Remove the original tuning pot and enlarge the front panel hole so that a small rotary switch can be fitted instead. • Mount the PCB lower in the case to provide clearance for the switch. • Mount the five tuning pots on a piece of Veroboard, then wire the Flasher unit for cars Anyone who owns a car knows that can-type flasher units can be unreliable, particularly on older cars. They tend to break down after a few years. This simple circuit provides a more reliable alternative. It can be built for just a few dollars and uses 555 timer IC1 wired in astable mode to pulse a relay on and off. As a bonus, it can also provide a hazard light function - a feature not found on older cars. In use, the relay provides audible indication that the flasher is operating but you could also install a .piezo buzzer if you so wished. The circuit is designed to replace a 2-pin flasher unit, as fitted to most Japanese cars. The unit is simply wired into 46 SILICON CHIP I I I I I IN I .,. _J EXISTING CIRCUIT OUT ,.. ,~Rolsi----------.,. UHF TUNING MODULE - - - - l'V+ Fig.1: this simple circuit modification provides switched station selection on the DSE UHF Converter. Veroboard to the switch using stiff tinned copper wire to provide the necesary electrical connections and mechanical support. • Connect the converter to your TV set as before and adjust the trimpots for best reception of each channel. ---""'1GAIN .,. If the tuning is too touchy on a particular channel, then the range of the trimpot can be reduced by adding a resistor in series with it. M. Allen, Gore Hill, NSW. ($25) OLD FLASHER UNIT IGNITION 0---0-,-:,LIN"'°K-o--o-- ~AMPS i o--RIG,-HT-----------41-----+-_. I I I I I 'RELAY ICl 555 ALL DIODES 1N4002 .,. Fig.2: this flasher circuit can also provide a hazard light function. circuit after the indicator switch. Note that the original flasher unit must be removed and replaced by a wire link. John Pindell, Woodbridge, Tasmania. ($15) Fuse-£ail alarm for cars Fuse failure in a car or truck is not always obvious to the driver but can create a dangerous situation. This is particularly so if a fuse fails in the supply line to the brake lights or tail lights. This circuit overcomes that problem. It is simply wired across the fuse to be monitored and sounds a buzzer and lights a LED if the fuse blows. As shown, the circuit consists of two identical sections based on exclusive-OR (XOR) gates from a 4070 IC package. Since each section is the same, we'll look only at the circuit associated with IC1a. The two inputs of IC1a monitor each side of the fuse via identical resistor/zener diode networks which reduce voltage spikes to a safe level. If the fuse is intact, both inputs to IC1a will be same (ie, both high when the power is on and both low when the power is off). Thus IC1a's output will be low and so LED 1, transistor Ql and the buzzer will all be off. Now consider what happens if fuse 1 blows. Now, when power s.sn FUSE 1 10k ':' +12V + BUZZER .,. .,. s.sn .,. FUSE 2 -: is applied, pin 1 will go high (ie, to + 12V) while pin 2 will remain low. Pin 3 of IC1a will thus switch high, turning on LED 1, Ql and the buzzer. Diodes Dl and DZ form a simple OR gate between the XOR gate outputs and the transistor. You can easily expand the circuit to monitor additional fuses simply by adding more XOR gates (there are four in the 4070 package) and duplicating the circuitry up to the 4.7k0 resistor. Peter Howarth, Narrabri, NSW. ($20) Car battery voltage monitor This unit is intended for use with a 12V lead-acid battery and may be set to operate at any point between 12V and 14V by adjusting VR1. It compares the voltage of the battery with the voltage of zener diode ZD1. ZD1 and diode Dl set the base bias on transistor Ql while trimpot VR1 sets the base bias on Q2. When the battery output rises above the preset voltage, Q2 turns on and LED 2 lights. This, in turn, drives up Ql 's emitter voltage and so Ql and LED 1 turn off. Conversely, when the battery voltage falls below the preset value, Q2 and LED 2 turn off and Ql and LED 1 turn on. The zener diode used was found to have a positive temperature coefficient. This problem was solved by connecting Dl in series with it to reduce the resulting change in voltage with changes in temperature. The current drawn by the circuit is only about 20-30mA. J. Emery, Bullcreek, WA. ($15) Have you got a good circuit idea languishing in the ol' brain cells? If so, why not send it in to us and save us from circuit burnout? We'll pay up to $50 for a really good circuit. So transfer your circuit to paper and send it to SILICON CHIP, PO Box 139, Collaroy Beach, NSW 2097. AUGUST 1989 47 Don't get caught with an overflowing bin Build the garbage reminder Did you for get to put out the garbage this week? Isn't it frustrating? There you are with an overflowing bin and nowhere to put the excess. You can avoid that problem in the future by building our Garbage Reminder. It will flash a reminder to you on each garbage night. By JOHNNO 'BLUE SINGLET' CLARKE While not the most life threatening problem presently confronting the planet, forgetting to put out the garbage is a pain. Either you remember next morning when it is far too late or perhaps you remember at the very last minute and have to sprint after the garbage truck dressed in your slippers and "jarmies". Have you heard the joke about the little old lady who remembered to put out the garbage at the very last minute? Calling out to the garbage collectors, she said, "Am I too late?" "No luv, jump in." She needed our Garbage Reminder, didn't she? Our Garbage Reminder is a small battery powered unit which has a flashing LED to indicate when it is garbage night. When you've put the The Garbage Reminder is battery powered and will flash a LED for 7 hours whenever it's garbage night. To turn the LED off, just press the "BIN OUT" switch in the middle of the truck. 48 SILICON CHIP bin out, you then press the BIN OUT switch to stop the LED flashing. You can set the Garbage Reminder to flash the LED on any evening of the week. Say your garbage nights are Monday and Thursday. Just set the Garbage Reminder to flash the LED on those nights and you will never have a garbage debacle again. Of course, you need to put the Garbage Reminder where you will see it before you go to bed. You could stick it to your fridge door, bathroom mirror, bedside table or whatever. Now you might wonder why we would bring the full engineering talents of SILICON CHIP engineers to bear in solving a trivial problem like this but think about it. It is not all that easy to solve. You need a timer which can be set to flash a LED on any one or two (or more up to seven) nights a week and it must do it accurately. You don't want to have to reset it every month or so, do you? Furthermore, it must provide an effective reminder and run very economically from batteries. Naturally, it can't run on mains power because a blackout might upset the timing and then where would you be? You might put the garbage out on the wrong night! So that sets the circuit requirements. It must be accurate, battery operated and economical. That means it must be crystal controlled, run from CMOS ICs and have a very low current drain. The batteries should last around a year. or more. Naturally, while we have presented the timer as a Garbage +3V 16 16 32.768kHz 10 10 16VW .,. + - 10M 1------.. +8640 - - - - - ----l POWER ON RESET +3V 100k .,. 10CYCLES/24HRS + +3V .01 i 16 R 15 IC& 4017 +10 co n D 8 IC7 4017 +7 ICYCLE124HRS 13 7 ..I. R 15 3 8 13 .,. .,. 01 100k .,. 1M .001+ 11 2.2k LED1 . . - - - - , 6 A 1' ICB LM3909 K 100 6 F2_\-IVll-~---1' 8 EOc .,. VIEWED FROM GARBAGE REMINDER Fig.1: the circuit uses a readily available 32.768kHz watch crystal as the timebase. This is divided down by IC2, IC3, IC5, IC6 & IC7 to obtain a weekly cycle. The DIP switch (S1) selects the days while IC8 flashes the LED. Reminder it could be used to remind you of other tasks such as taking daily medication (the pill?], feeding the goldfish or remembering to go to work (or better still, when to stay home]! Space age styling In line with the fairly prosaic nature of the task it is supposed to remind you to do, the Garbage Reminder has pretty ordinary looks. It is just a plastic box with a light emitting diode and a pushbutton on it. There is no on/off switch (you don't want anybody inadvertently switching it off] and there is no visible means of setting it - that's inside. We have provided an interesting front panel label though, with a picture of a garbage compactor truck on it. Like it? Inside the case is a miniature 8-way DIP (dual inline package) switch. Seven of these switches are used to nominate the days you want to be reminded to put the garbage out. Switch 8 doesn't do anything. How do you set the Garbage Reminder? Easy. Say it's 5 o'clock on Monday and tonight is garbage night and so is Thursday night. OK. Set switches 1 and 4 to the ON position and all the others off. Now connect the batteries and the LED will AUGUST 1989 49 POLYESTER & CERAMIC CAPACITORS No. □ □ □ □ □ □ □ 1 2 1 1 1 1 1 Value 0.1µF .047µF .01µF .001 BµF .001µF 33pF 10pF IEC 100n 47n 10n 1n8 1n 33p 10p EIA 104K 473K 103K 182K 102K 33K 10K RESISTORS No. □ □ □ □ □ 1 4 3 2 1 Value 10MO 1MO 220k0 100k0 2.2k0 start flashing at the rate of about once every two seconds. It will continue to flash for 7 hours 12 minutes unless the BIN OUT switch is pressed. That's all you have to do. The Garbage Reminder will now continue to work until the batteries go flat which should be at least 12 month's away. More likely, we expect alkaline cells to last around 2 years or so. Circuitry The Garbage Reminder -uses 8 CMOS !Cs, plus a few diodes, a crystal, a LED and some resistors and capacitors. The !Cs are all low cost devices and draw very little current which makes them suitable for battery operation. Why so many !Cs? We had to use readily available parts and a cheap and readily available quartz crystal to give an accurate time reference. Therefore we used a 32kHz watch crystal which is just about the cheapest type you can get. The precise crystal frequency is 32.768kHz. This has to be divided down by a factor of 1.9818 x 1010 to obtain a weekly cycle. That sounds like a huge division ratio and so it 50 SILICON CHIP 4-Band Code (5%) brown black blue gold brown black green gold red red yellow gold brown black yellow gold red red red gold 5-Band Code (1%) brown black black green brown brown black black yellow brown red red black orange brown brown black black orange brown red red black brown brown is. Let's see how it is achieved. NAND gate IClc (4011) operates as the crystal oscillator. It is biased with lOMO and 220k0 resistors so it functions as a high gain inverting amplifier. The 32kHz crystal is connected across the lOMO resistor while the lOpF and 33pF capacitors provide the correct loading for it. The square wave output of IClc is a 32.768kHz signal which may appear to be a strange oscillator frequency to use for a clock circuit. In fact, 32,768 is 215. Following IClc is IC2, a 4020 14-stage binary divider. Its output at pin 3 (Q14) is a square wave at 2Hz. There is also a test signal at the Q4 output (pin 7) at 2.048kHz but more on that later. The 2Hz signal from IC2 is fed to IC3 which is another 4020 14-stage binary counter. Together with 4-input AND gate IC4 and JK flipflop IC5, IC3 provides a division ratio of 8640. This results in an output at pin 15 of IC5a of 20 cycles per day. How do IC3, IC4 and IC5a provide a division by 8640? There are four outputs taken from IC3 and these are Q7, Q8, Q9 and Q14. The Q14 output goes high after 8192 counts, Q9 goes high 256 counts after Q14 goes high, Q8 goes high 128 counts after Ql4 goes high and finally Q7 goes high 64 counts after Q14 goes high. When all these outputs are connected to the 4082 4-input AND gate, IC4, the output goes high after the sum of 8192 + 256 + 128 + 64, or 8640. Further, the pulse from IC5a is divided by two to provide a square wave at the rate of 10 cycles per day. This 10 cycles per day output is then fed to IC6, a 4017 decade counter/divider which gives out one positive-going pulse (lasting 12 hours) every 24 hours from its output at pin 12. This one pulse per day output is fed to IC7, another decade divider and its outputs are fed to the "day select" DIP switch Sl. Diodes Dl to D7 isolate each of the "day" outputs so that they don't load each other if more than one day per week is selected. The selected day outputs from the DIP switch are fed to NAND gate ICld together with a 2.4-hour pulse output from pin 3 of IC6. ICld's output is then fed to an RS flipflop consisting of IC la and !Cl b. The output of this flipflop, at pin 3, is turned on PARTS LIST 1 plastic case , 130 x 67 x 43mm (Altronics Cat. H0153) 1 front panel label, 125 x 64mm 1 PCB, code SC081 08891 , 105 x 60mm 1 8-way DIP switch 1 momentary contact pushbutton switch 1 battery snap connector 1 2-cell AA battery holder (Jaycar Cat. PH-9202) 2 1.5V alkaline AA cells 1 32 . 768kHz miniature (watch) crystal Semiconductors The assembled PC board simply clips into the bottom of the specified plastic case. Power comes from two 1.5V alkaline AA cells. The DIP switch is used to set the nights that the LED is to flash. To select each night, just slide the corresponding slider to "ON" (see text). (set) by the output of ICld; and pin 3 is pulled low (reset) when the ' 3' output of IC6 goes high and is inverted by transistor Ql. Similarly, the flipflop can be reset early by pressing the BIN OUT switch, S2 . RS flipflop IC1a/IC1 b actually powers IC8, an LM3909 LED flasher . This causes the LED to flash at a rate of about once per se- cond, depending on the condition of the batteries. So what happens is that, when one of the day outputs from IC7 goes high, the RS flipflop allows the LED to start flashing when the 'O' output (pin 3) of IC6 goes high. The LED then stops flashing 7. 2 hours later, when the flipflop is reset by the ' 3' output of IC6. That is, unless you put your garbage bin out and then remember to press the BIN OUT switch. To ensure that all the counter ICs in the circuit operate correctly when power is first applied, they are all reset automatically. For IC2 to IC7, all the reset pins are connected to the junction of a 10µ,F capacitor (the other side of which is connected to the positive supply] and a 100k0 resistor to ground. When power is first applied, the 10µ,F capacitor is discharged and so it effectively pulls the reset line to the positive supply, resetting IC2 , IC5a, IC5b and IC6 directly and indir ectly, IC3. IC3 is reset when the Ql output of IC5a goes high at the power on reset. Once the 10µ,F capacitor charges, the power on reset line goes to ground and normally counting can take place. 1 4011 quad 2-input NANO gate (IC1) 2 4020 14-stage counters (IC2, IC3) 1 4082 dual 4-input AND gate (IC4) 1 4027 dual JK flipflop (IC5) 2 4017 decade counter/dividers (IC6, IC7) 1 LM3909 LED flasher (IC8) 8 1 N914 diodes (D1 to D8) 1 BC54 7 NPN transistor (Q1) 1 5mm high brightness LED Capacitors 1 1 1 1 2 1 1 1 1 1 100µ,F 16VW PC electrolytic 4 7 µ,F 16VW PC electrolytic 1 Oµ,F 16VW PC electrolytic 0 .1 µ,F metallised polyester (greencap) .04 7 µ,F metallised polyester .01 µ,F metallised polyester .0018µ,F metallised polyester .001 µ,F metallised polyester 33pF ceramic 1 OpF ceramic Resistors (0 .25W, 5%) 1 10MO 4 1 MO 3 220k0 2 1 OOkO 1 2.2k0 Miscellaneous Tinned copper wire for links, hookup wire for switch, solder, etc . IC7 has its own power-on reset network, consisting of a .01µ,F capacitor and 100k0 resistor. IC7 is also reset at the end of a 7-day period when pin 6 goes high. This is connected to pin 15 via D8 and thus resets IC6 so that all outputs are low. AUGUST 1989 51 penetrate the front panel. Finally, wire up the BIN OUT switch and the battery clip leads. The circuit is now ready for testing. Testing o 1111 F I ~ I I ""-.........._ ....____.o_a_1_oa_s_9_1_ ...._, Fig.3: here is an actual size artwork for the PC board. GARBAGE REMINDER BIN OUT Fig.4: in keeping with the styling, the front panel features a garbage compactor truck. You'll never forget the garbage again. The whole circuit is powered from two AA cells in series, giving 3V. We recommend the use of alkaline cells for longest battery life. By the way, the circuit will work with the battery voltage down to below 1.8 volts. Construction The Garbage Reminder is built into a standard plastic case measuring 130 x 67 x 43mm (Altronics Cat. H-0153). All the circuitry is mounted on a printed circuit board measuring 105 x 60mm (code SC08108891). Begin construction by carefully inspecting the printed circuit board tracks for opens and shorts between tracks. The PCB is designed to sit in the base of the specified case on the integral supports. Make sure the board is a neat fit into the case 52 SILICON CHIP before you assemble any components onto it. Start assembly of the PCB by inserting and soldering in the links and resistors. Do not install Link 1 at this stage. Install Link 2 instead. This is done for initial testing of the circuit and makes it run 1024 times faster than normal. Next install diodes D1 to DB making sure that they all point in the same direction (band ends closest to IC3). The ICs can go in next and they are all oriented in the same direction. Check that each IC is correctly in place before soldering. When installing the DIP switch make sure that it is oriented so that switch 8 is closest to the diodes. This done, install the capacitors, crystal and LED. The LED is mounted with the leads long enough (say about 22mm) so that it can just Firstly, set DIP switches 1 to 7 to the "on" position. Switch 8 can be set either way since it is not in circuit. This will cause the LED to flash on every day. Now insert the two AA cells into their holder to power up the circuit. The LED should then flash at about once a second for about 25 seconds (yep, that means it should flash about 25 times). 59 seconds after it stops flashing, it should flash again, for 25 seconds. What is happening is that each day's cycle has been speeded up by 1024 times so that a 24 hour period is simulated in 84.375 seconds. Knowing that, you can check that the unit cycles correctly for any combination of days set by the DIP switch. Note that each time you change the DIP switch settings, you need to remove the batteries and short out the battery snap connector so that the circuit is properly "powered down". If you don't do this, the circuit won't properly reset itself. Powering up should always start the circuit timing from day 1. You can also check the function of the BIN OUT pushbutton - does it stop the LED from flashing? Once the circuit operation is proven, link 2 can be rerp.oved and link 1 inserted. The Garbage Reminder will now operate over a 7 day cycle. Installation The front panel label can be fixed to the plastic lid and a 5mm hole drilled for the LED. This hole should be positioned so that the LED becomes the rear flasher of the garbage truck logo on the panel. The switch cutout is located just below the BIN OUT labelling. Now clip the PCB into place and check that the LED penetrates through the lid sufficiently. Adjust the height of the lid as necessary if you encounter problems at this step. The Garbage Reminder is now complete and all that is left to do is to set the DIP switches. continued on page 79 KIKUSUI Cos-&100 100MHz . 3ch. CRO with DaAY • Display: CH1. CH2. CH1 CH2. EXT. X-Y. • Sweep Modes: Auto. Normal. Single Shot • Trigger Coupling: AC, DC, HF-REJ, 1V. • Sourte: VertMode, CH1 , CH2, EXT & LINE. • Sensitivity: SmV/DIV to SV/DW, DC to 100MHz. • Timebases: 2ns/DW to 0.5s/DIV. both A and B. "Includes 2 x 1:1 and 10:1 probes. • 2 year Warranty. $3,238.00 incl. tax. $2, 77&.94 ex. tax. KIKUSUI COS-5080 80MHz 3ch. CRO with DaAY • • • • • • • • Display: CH1. CH2. CH1 CH2. EXT. X-Y. Sweep Modes: Auto. Normal. Single Shot Trigger Coupling: AC, DC, HF-REJ, 1V. Sourte: VertMode, CH1. CH2. EXT & LINE. Sensitivity: SmV/DIV to fN/DW. DC to 61MHz. Timebases: 2ns/DW to 0.5s/DIV. both A and B. Includes 2 x 1:1 and 10: 1 probes. 2 year Warranty. $1.929.00 incl. tax. $1,853.75 ex. tax. GOODWIU GOS,,,$43 40MHz 2ch. CRO with DaAY • Display: CH1 . CH2. DUAL. CH1 CH2.X-Y. • Sweep Modes: Auto. Normal. Single Shot • Trigger Coupling: AC, DC, HF-REJ, 1V. • Sourte: CH1. CH2, EXT & LINE. • Sensitivity: 5mV/DIV to fN/DW. DC to 4™Hz. • Timebase {a): 20ns/DIV to 0.5s/DW {main). • Timebase {b): 20ns/DIV to 0.5ms/DW {delayed * lncludes2x 1:1 and 10:1 probes. • 12 months Warranty. $1,247.00 incl. tax. $1,069.20 ex. tax. GOODWIU GOs-&22 20MHz 2ch. CRO • Display: CH1 . CH2. DUAL. CHI CH2. X-Y. • Sweep Modes: Auto, Normal. Single Shot • Auto Trigger level Lock. Variable Hold-Off. • Trigger Coupling: DC. Vertical Trigger Mode. • Sensitivity: 5mV/DIV to fN/Dr.J. DC to 20MHz. • Timebase: 20ns/DW to 0.5s/DIV. * lnclu~es 2 x 1:1 and 10:1 probes. • 12 months Warranty. $799.00 ind. tax. $704.08 ex. tax. · KIKUSUI COS-5041 40MHz 2ch. CRO with DELAY • Display: CH1. CH2. CH1 CH2. X-Y. • Sweep Modes: Auto. Normal. Single Shot • Trigger Coupling: AC, DC. HF-REJ, lV. • Sourte: Vert Mode, CH1 . CH2. EXT & LINE. • Sensitivity: 5mV/DIV to fN/DW, DC to 4™Hz. • Timebase (a): 20ns/DIV to 0.5s/DW (main). • Timebase (b): 0.2us/DW to 0.5ms/DW (del) "Includes 2 x 1:1 and 10:1 probes. • 2 war Warrantv. $1,424.00 incl. tax. $1,220.83 ex. tax. GOODWILL G0&-3310 10MHz 1ch. CRO • Sweep Modes: Auto. Normal. • Display: X-Y operation. • Sensitivity: SmV/DIV to fN/DW, DC to 10MHz. • Timebase: 10ms/DIV to 0.1 us/Dr-I. • Includes probe. • 12 months Warranty. $445.00 incl. tax. $381.84 ex. tax. KIKUSUI CC>S-8020 20MHz 2ch. CRO • Display: CH1, CH2. CH1 CH2, X-Y. • Sweep Modes: Auto, Normal, Single Shot • Trigger Coupling: AC, DC, HF-REJ, lV. • Sourte: Vert Mode. CH 1, CH2. EXT & LINE. • Sensitivity: 5mV/DIV to fN/DW. DC to 20MHz. • Timebases: 20ns/DW to 0.5s/DW. " Includes 2 x 1:1 and 10:1 probes. • 2 year Warranty. $930.00 ind. tax. $799.40 ex. tax. GOODWILL GOs-956 5MHz 1ch. CRO • • • • • Sweep Frequency: 10Hz to 100kHz in 4 Rang Sensitivity: lOmV/DIV to 1V/DW, DC to 5MHz. Synchronization: Internal. External. Includes probe. 12 months Warranty. $445.00 ind. tax. $381.84 ex. tax. HITACHI V•212 20MHz 2ch CRO LABTECH 20MHz 2ch. CRO with COMPONENT TESTER • Deflection Factor. SmV to 2fN/DIV on 12 Ranges. • Operating Modes: CH-A. CH-B, DUAL and ADD. • Sweep Time: 0.2us to 0.5s/DW on 20 Rarges. • Sourte: INT. CH-B, LINE. or EXT. "Includes 2 x 1:1 & 10:1 probes • 12 months Warranty. $799.00 incl. tax. $894. 78 ex. tax. • Deflection Factor. SmV to fN/DIV in 10 calibrated steps. • Display Modes: CHI. CH2. Alternate. Chopped, Added. $998.00 ind. tax. • Time Base: 0.2us/DIV to 0.2s/DW in 19calibrated steps. $888.08 tax • Trigger Modes: AUTO, NORMAL. 1V {TV-Hor lV-V}. • Trigger Sourtes: Internal {CH1, CH2. V-MDDE). Line. External. "Includes 2 x 1:1 and 10:1 probes. • 2 Year Warranty. PI ices subject to change w~hout notice DAVID REID ELECTRONICS 127 York St. Sydney NSW 2000 Phone: (02) 267 1385 ex. Business Hours Mon • ffi 8.30 • 5.30 TJ..-sday 8.30 • 7.00 Saturday 9.00 • 1.00 GOODWILL GFC-8010G 120MHz FREQUENCY COUNTER LABTECH 1GHz FREQUENCY COUNTER • Frequency Range: 1Hz to 120MHz • Sensitivity: < 20Mv 1OHz to 100MHz. < 30mV 100MHz to 120MHz • Display: 8 digit • Gate time: 0.1s. 1s. 10s. • Frequency Range: CH A: 10Hz to 100MHz. CH B: 100MHz to 1GHz • Input Sensitivity: CH A: 20mV RMS. CH B: 15mV RMS • Display: Bdigit • Gate time CH A: 0.01s,0.1s. 1s. 0.1s. CH B: 0.027s. 0.27s. 2.7s $270.00 incl. tax $235.82 ex. tax $499.00 incl. tax $433.91 ex. tax ESCORT EFC-2203 1.3GHz FREQUENCY COUNTER ITc-4120MHz INTEWGENT COUNTER • Frequency Range: 5Hz to 1.3GHz • Period Measurement 0.286us to 0.2s, 100ps resoulation. • Pulse Counter. 0 to 99,999,999 counts. 5Hz to 10MHz. • Sensitivity: Input A: 20mV<at> 100MHz. Input B: 50mV <at> 1.36GHz. • Display: 8 digit • Gate time: O.Ols. 0.1s. 1s. 10s. $722.00 • Frequency Range: 10Hz to 120MHz • Sensitivity: 20mV<at> 120MHz typically • Resolution: 1Hz for 100MHz input • Gate time: 60ms to 1Os. continuously variable. $838.00 incl. tax $554.40 ex. tax lncl. tax $829.11 ex. tax GOODWILL GFG-8015G 2 MHz FUNCTl()N GENERATOR GOODWILL GFG-8020G 2MHz FUNCTION GENERATOR • Frequency Range: 0.2Hz to 2MHz, continuously variable. • Output Waveforms: Sine. Triangle, Square. TTL pulse and Ramp. • Output l..ellel: > 20V p-p Open Cin:uit. 10V p-p into 50ohms. • DC Offset of+/· 10V DC. • 4 digit LED display for frequency indicati111. • Frequency Range: 0.2Hz to 2MHz. continuously variable. • Output Waveforms: Sine. Triangle. Square. TTL pulse and Ramp. • Output l..ellel: > 20V p-p Open Cin:uit. 10V p-p into 50ohms. • Variable D_uty Cycle: of 1:10 to 10:1. $399.00 incl. tax $349.29 ex. tax $278.oo lncl. tax $239.91 ex. tax GOODWILL GFG■8017G 2MHz FUNCTION GENERATOR with SWEEP FUNCTION • Frequency Range: 0.2Hz to 2MHz. continuously variable. • Output Waveforms: Sine, Triangle, Square, TTL pulse and Ramp. • Output l..ellel: > 20V p-p Open Cirtuit. 10V p-p into 50ohms. • Auto or Manual Sweeping. • Sweep width: 1000:1 ratio. • Sweep time: variable from 0.5s to 30s. • Sweep modes: LIN. LOG (Hi/1.o). $420.00 incl. GOODWILL GFG-8016G 2MHz FUNCTION GENERATOR with FREQ. COUNTER $490.00 incl. tax $425.U ex. tax tax $384.48 ex. tax RJNCTION GENERATOR SPECIRCATIONS • Frequency Range: 0.2Hz to 2MHz. continuously variable. • Output WavefCl'ms: Sine. Triangle. Square. TTL pulse and Ramp. • Output l.ellel: > 20V p-p Open Cirtuit. 10V p-p into 50ohms. FREQUENCY COUNTER SPECIRCATIONS • Internal and External operation. • Frequency range: 0.1Hz to 10MHz • Sens: > 20mV AMS 10MHz. • Display: 6 Digit LED. GOODWILL GRG-450 RF SIGNAL GENERATOR GOODWILL GAG-808B AUDIO SIGNAL GENERATOR • Frequency Range: 100KHz to 150MHz (450MHz on Hannonics) • RF Output 100mV RMS, up to 35MHz • Modulation: NA internal and external. • 12 Months Warranty. • Frequency Range: 10Hz to 1MHz. in 5 ranges. • Sinewave Output: > 20V p-p; Di3tortion < 0.1 % • Squarewave Output> 10V p-p; Risetime < 200ns. • Output Impedance: 600ohm. • 12 Months Warranty. $211.00 incl. tax $222.43 ex. tax GOODWILL GVT-418 AC MILLIVOLT METER • Measurement range: 1mV to 'JOOtl AC RMS • Frequency Response: 5Hz to 1MHZ. +/· 5% • 12 Months Warranty $215.00 incl. tax $222.43 ex. tax GOODWILL GVT-417 AC MILLIVOLT METER • Measurement range: 300uV to 100V AC RMS • Frequency Response: 20Hz to 200<HZ. +/· 3% • 12 Months Warranty $238.00 incl. tax $207.90 ex. tax DAVID REID ELECTRONICS 127 York St. Sydney NSW 2000 Phone: (02) 267 1385 $240.00 lncl. tax $210.87 ex. tax Business HOO's Mon · fri 8.30 • 5.30 Thursday 8.30 • 7.00 Saturday 9.00 • 1.00 R.UKE 73 DIGITAL MULTIMETER • Display: Analog/Digital (3.5 digit) • Ranges: Volts. Ohms, Current, (10A AC/DC), Diode Test. • Autoranging • 0.7% basic DC Accuracy • Includes Probes • 3 Year Wanranty • Display: Analog/Digital {3.5 digit) • Ranges: Volts, Ohms, Current, (10A AC/ DC)mA. Diode Test • Auto/Manual Ranging • 0.5% basic DC Accuracy • Audible continuity • Includes Probes • 3 Year Wanranty $153.50 incl. tax $128.00 ex. tax $249.00 incl. tax $208.00 ex. tax • Display: Analog/Digital (3.5 digit) • Ranges: Volts. Ohms. Current. {10A AC/DC)mA, Diode Test • Auto/Manual Ranging • Touch Hold Function • 0.3% basic DC Accuracy • Audible continuity • Includes Probes and Holster • 3 Year Wanranty $340.00 incl. tax $284.00 ex. tax R.UKE 83 DIGIT AL MULTIMETER • Display: Analog/Digital (3.75 digit) • Ranges: Volts. Ohms. Current, (10A AC/DC)mA. uA. Frequency, Capacitance and Diode Test • Touch hold and Relative Modes. • Min/Max/Awrage recording mode with Min/Max alert • Input Alert and CNerload protection. • 0.3% basic DC Accuracy • Audible continuity • Includes Probes and Holster • 3 Year Wanranty ESCORT EDM-55 PROBE TYPE DIGITAL MULTIMETER • • • • • Display: 3.5 digit LCD Ranges: Autoranging, AC. DC. V. Ohms. Diode test Data Hold and Audible continuity 12 Months Warranty $67.00 incl. tax $58.29 ex. tax ESCORT EDM-1348A TRUE RMS DIGITAL MULTIMETER ESCORT EDM-1122 DIGITAL MULTIMETER • Display: 4.5 digit LCD "Ranges: AC. DC. V. Ohms. Current {10A AC/DC). Frequency, Diode test • Data Hold function • Audible continuity with LCD indication. • Includes probes • 12 Months Wanranty • Display: 3.5 digit LCD • Ranges: AC. DC, V, Ohms, Current{20A AC/ DC). Capacitance. Frequency, Diode test. Transistor HFE Test. Logic Level Test • Audible continuity. • Includes probes • 12 Months Wanranty $189.00 lncl. tax $183.35 ex. tax $133.00 incl. tax $118.12 ex. tax $418.50 incl. tax $349.00 ex. tax R.UKE 85 DIGITAL MULTIMETER • Display: Analog/Digital (3.75 digit) • Ranges: Volts, Ohms, Current, (10A AC/DC)mA. uA. Frequency, Capacitance and Diode Test • Touch hold and Relative Modes. • Min/Max/Average recording mode with Min/Max alert • Input Alert and CNerload protection. • 0.1 % basic DC Accuracy • Audible continuity • Includes Probes and Holster • 3 Year Wanranty $492.00 incl. tax $419.00 ex. tax R.UKE 87 TRUE RMS DIGITAL MULTIMETER ESCORT EDM-188 DIGITAL MULTIMETER • Display: 3.5 digit (CD • Ranges: AC V. DC V. Ohms. Current (20A AC/ DC). Diode test. Transistor HFE Test • Audible continuity. • Includes probes • 12 Months Wanranty $78.50 incl. tax $87.74 ex. tax ESCORT EDM-188 DIGITAL MULTIMETER ESCORT EDM-70H DIGITAL MULTIMETER • Display: 3.5 digit LCD • Ranges: AC V. DC V. Ohms. Current (20A AC/DC). Diode test. Transistor HFE Test. Frequency, Capacitance. • Audible continuity. • Includes probes • 12 Months Wanranty • Display: 3.5 digit LCD • Ranges: AC V, DC V. Ohms. DC A (2A). Diode test. Transistor HFE Test • Includes probes • 12 Months Wanranty $102.75 incl. tax $88.58 ex. tax $51.00 incl. tax $44.09 ex. tax Mail Orders: P.O. Box 0103 Sydney NSW 2000 Fax: (02) 261 8905 P&P Rates $5-$25 $26-$50 $4 $6 $51+ $8 • Display: Analog/Digital (4.5 digit). Back-Lit display. • Ranges: Volts. Ohms, Current. (10A AC/DC) mA. uA. Freq .• Capacitance & Diode Test • Touch hold and Relative Modes. • Min/Max/Average recording mode with Min/Max alert • Input Alert and CNerload protection. • 0.1 % basic DC Accuracy • Audible continuity • Includes Probes and Holster • 3 Year Warranty $578.00 incl. tax $480.00 ex. tax ■ -.c-l;=J VISA ESCORT EDC-110A DIGITAL CAPACITANCE METER • • • • • Display: 3.5 digit LCD Measurement range: 200pf to 20 milli-farads Resolution: 0.1pf max. Includes Probes 12 months Warranty SEW ST-321 TAUT BAND ANALOG MULTIMETER • Display: 3.5 digit LCD • Ranges: capacitance - 200pf to 2000uf. 0.1 pF resolution, Inductance - 200uH to 200H. 100nH resolution. Resistance 200ohm to 20M ohm. 10 ohm resolution • Includes Probes • 12 Months Warranty $110.00 incl. tax $95.33 ex. tax $224.00 incl. tax $194.34 ex. tax SEW ST-380TR ANALOG MULTIMETER SEW ST-SOS LAB ANALOG MULTIMETER • 20K ohm/v sensitivity • Ranges: AC V. DC V. DC A, Ohms. dB. Transistor Checker • Continuity checker • Fuse and Diode protection • Includes test Leads • 12 Months Warranty • SOK ohm/v sensitivity * Ranges: AC V. DC V. Current(10A AC/DC). Ohm. dB. • Shock Proof movernent • Fuse and Diode protection • Includes test leads • 12 Months Warranty $38.00 incl. tax $33.31 ex. tax $62.00 incl. tax $54.33 ex. tax EMTEK DCT-310 AC/DC DIGITAL CLAMP METER • Ranges: AC A {200,400 amps) DC A{200,400 amps) AC V (200.750 volts) DC V (200.1000volts) • Temperature: -40C to +750C. K type input • Diode Check • Peak Hold for transient measurements • Data Hold for displayed values • Includes Probes and carry case • 12 Months Warranty $167.00 incl. tax $145.02 ex. t,x SEW ST-7 ANALOG METER • 2K ohm/v sensitivity • Ranges: AC V, DC V. DC A. Ohm. Battery Test. dB. • Pocket sized • Includes test leads • 12 Months Warranty $19.00 incl. tax $16.65 ex. tax SEW ST-300 ANALOG CLAMP METER • Ranges: AC A(0-6.15.60.150,300amps) AC V (0-150,300,600 volts) • Shock Proof movement • Fuse Portection • Includes test leads • 12 Months Warranty $72.00 incl. tax $62.57 ex. tax • 20K ohm/v sensitivity • Ranges: AC V, DC V. DC A. Ohms. Battery Test • Fuse and Diode Prota:tion. • Drop Proof movement • Includes Test Leads • 12 Months Warranty $38.00 incl. tax $33.31 ex. tax ESCORT ECT-840 DIGITAL CLAMP METER • Ranges: AC A {200,300 amps) AC V (200.750 volts) Ohms {2K ohms) • Includes test leads and carry case • 12 Months Warranty $77 .00 incl. tax $66. 73 ex. tax ,<\:\.-._--. -;::r;>·· -~ ESCORT ELP-800 LOFIC PROBE DLC,,200 AC/DC CURRENT ADAPTOR • Ranges: 200A, 400A AC & DC ±2% 4 digits • Output 1mV/A 200mV/200A & 400mV/400A • 12 month warranty $92.00 incl. tax $80.00 ex. tax • TTL or CMOS compatible • Frequency: > 17MHz • Detection Pulse: < 301s • Input impedance: 1Mohm • Hi. Lo and Pulse LED's • Audible beeper output • 12 Months Warranty ESCORT ELP-810 LOGIC PULSER $35.50 incl. tax $30.89 ex. tax $35.50 incl. tax $30.89 ex. tax • • • • Pulse repition rate: 0.5/400 PPS Pulse width at 100mA load: 10us Sync input impedance: 1Mohm 12 Months Warranty DAVID REID ELECTRONICS 127 York St. Sydney NSW 2000 Phone: (02) 2671385 Business Hours Mon - Fri 8.30 - 5.30 Thursday 8.30 - 7.00 Saturday 9.00 - 1.00 "IBM XT/AT compatiable. • Tracing Speed: 200mm/sec. • Resolution: 195 dots/inch. only $79.95 • Tracking speed: 600mm/sec • Resolution: 200 DPI • Includes driver and test program and mouse pad • • • • • only $99.95 MOUSE PAD- Enhance function for your mouse ... $14.95 10 Signal powered LED's for monitoring activities 24 DIP switches allll\l\l you to cut out or reconfigure 25 pin 'D' plug to socket for in-line installation Monitors TD/RD/RTS/CTS/DSR/CD/TC/RC/DTR Complete with jump wires only $89.95 RS-232 DATA SWITCH BOX LEAP-2.01 EPROM PROGRAMMER DB-25 TYPE 2WAY $59.00 4 WAY $89.00 36 PIN DATA SWITCH BOX CENTRONICS TYPE • 4 way Eprom Programmer for IBM-PC/XT/AT • There are over 26 commands to read. write. verify and modify data, as well as other functions including check sums and EPROMS erase. • Programs: 2716/A to 27512/A including NMOS/CMOS. EEPROMS 2804 to 58064 only $282.00 UV EPROM ERASER • Accepts 9 x 24 pin EPROM's • Compact size 2 WAY $59.00 4 WAY $89.00 PRINTER/GAME A/B SWITCHER - 25 PIN TYPE • 1 x DB-25 plug on 1.7mtr. cable to 2 x DB-25 sockets only $94.00 LF-2 MAINS FILTER • Safe guard against RF noise, control tones and voltage spikes. • 10 amp. max. load - 2 outlet · £ t 'NO NAME' 5.25" DSDDDISK'a _g I PKT-10 only $6.45 only $99.00 'NO NAME' 3.&" DSDD DISK'• LF-4 MAINS FILTER with OVERLOAD PROTECTION • 4 individually fitted outlets • Clamping voltage: 275V RMS • 10 amp max. load • Peak impluse current 2K A • 12 Months Warranty only $269.00 6 WAY POWER BOARD MAINS FILTER THE 'BUTTON' SPIKE PROTECTOR • 10 amp/2400watts • Response time:< 10n sec. only $59.91 only $29.95 PKT-10 only $29.95 DISK STORAGE BOXES for &.25" and 3.&" DISK'• • • • • 5.25' (HOLDS 100) LOCKABLE 5.25' (HOLDS 50) LOCKABLE 3.5' (HOLDS 80) LOCKABLE 3.5' (HOLDS 40) LOCKABLE DM-6012 DMM with DATA BUS COMPUTER FANS • BOmmdia. • • 240volt • • Airflll\l\l: 30CFM • Speed: 2300rpm 0 120mm dia. • 240volt • Airflll\l\l: BOCFM • Speed: 2600rpm only $29.91 only $24.&0 11&V $29.1& 11&V $24.SO The DM-60120 is a standard 3.5 digit DMM with an inbuilt LT-DATA BUS Tenninal for transferring readings to a dedicated printer or computer. Interfacing to a computer is via the BF-232 converter which converts the LT-DATA Bus to serial RS-232 fonmat. • Ranges: DCV, ACV, DC A, AC A, Ohms • Diode and Transistor testing $115.50 incl. tax $100.17 ex. tax 24 volt DC BRUSHLESS COMPUTER FAN • Airflll\l\l: 23CFM • speed: 3100rpm ...only $29.98 FAN FINGER GUARDS - (METAL and PLASTIC) • 12()nm METAL ... $2.95 • 80nm METAL ... $1 .95 $19.95 $15.95 $29.95 $19.95 • 12()nm PLASTIC ... $1.95 • 80mm PLASTIC ... $1 .95 BF-232 BUS CONVERTER Mall Orders: P.O. Box 0103 Sydney NSW 2000 Fax: (02) 261 8905 "lnputLT-DATABUS .. • Output RS-232C P&P Rates $5-$25 $4 $26-$50 $6 $51 + $8 $208.00 incl. tax $178,85 ex. tax ■~ t:.1 VISA DB-21 IN LINE PATCH BOX • Solder type • Includes jump wires $9.95 COMPUTER GENDER CHANQES * DB-25M to DB-25M * OB-25F to DB-25F * DB-9M to DB-9M $15.95 $15.95 $10.95 $10.95 • DB-9F to DB-9F RS-232 MINI TESTER • Monitors: TD/RO/RTS/CTS/OSR/CD/DTR $22.50 • CENTRONICS 36 PIN MALE to MALE ADAPTOR $15.95 • CENTRONICS 36 PIN F/F ADAPTOR $18.95 • CENTRONICS 36 PIN FEMALE to 08-25 MALE $15.95 DB-25 NULL MODEM ADAPTOR $9.95 • Pins 2 and 3 reversed NON-SOLDER TYPE PATCH BOX • DB-SM to DB-25M • DB-9F to DB-25M • DB-9M to DB-25F • DB-SF to DB-25F • DB-25 in line connection • Allows temporary reconfigeration * Includes jump wires $19.95 $10.95 $10.95 $10.95 $10.95 COMPUTER LEADS IBM COMPUTER LEADS * 08-9 FEMALE to 08-25 MALE 1.Bmtr • 8 PIN MINI DIN PLUG to DB-9 MALE 1.Bmtr • 8 PIN MINI DIN PLUG to db-9 FEMALE 1.8mtr • 08-9M to DB-9F MONITOR EXTENSION 3mtr * 5 PIN DIN M/F KEYBOARD EXTENSION 1.2mtr • 08-25 MALE to CENTRONICS MALE 1.8 mtr $9.00 • DB-25 MALE to CENTRONICS MALE 3 mtr $27.95 • DB-25 MALE to CENTAONICS MALE 5 mtr $36.95 $19.95 $ 9.95 $14.95 $ 9.95 $ 5.95 RS-232 SERIAL ~ -,m~=~•mtr LEADS COMPUTER LEAD • 08-25 MALE to DB-25 MALE 1.8 mtr $27.95 * 08-25 MALE to 08-25 FEMALE 1.8 mtr $27.95 ~ ' 36PINCENTRONICS ~ m~~ • 2 metre • 08-25 MALE * 08-25 FEMALE • 08-25 8/SHELL • 08-37 MALE • 08-37 FEMALE • 08-37 8/SHELL * 08-44 MALE • 08-44 FEMALE • DB-44 8/SHELL • DB-SO MALE • 08-50 FEMALE • DB-SO 8/SHELL $1 .50 $1.50 $1.50 $6.95 $7.45 $1.50 $1 .50 $1.50 $1.50 $2.59 $2.69 $1.50 $3.50 $3.50 $2.95 CENTRONIC CONNECTOR SOLDER TYPE IDC DB • SERIES CONNECTOR 24 WAY MALE 24 WAY FEMALE 36 WAY MALE 36 WAY FEMALE 50WAY MALE 50 WAY FEMALE DB-9 MALE DB-9 FEMALE DB-15 MALE DB-15 FEMALE DB-25 MALE OB-25 FEMALE DB-37 MALE DB-37 FEMALE $10.95 $12.45 $ 7.45 $ 9.75 $12.45 $13.75 CENTRONIC IDC TYPE 36WAYMALE 36 WAY FEMALE 50 WAY MALE SO WAY FEMALE SB.BO $ 9.95 $16.95 $17.95 lenght Only $47.95 MALE1.Bmtr $29. ~ DB SERIES CONNECTORS • SOLDER TYPE • D8-9 MALE • DB-9 FEMALE * DB-9 B/SHELL • 08-915 MALE • DB-915 FEMALE • DB-915 B/ SHELL • DB-15MALE • DB-15 FEMALE • DB-15 8/SHELL ' DB-19MALE • DB-19 FEMALE • DB-19 8/SHELL ' DB-23 MALE • DB-23 FEMALE • D8-23 8/SHELL • 25 pin 'D' M/M lead with DIP switches for simple wiring configeration changes. Allows various combinations for TXD/RXD and HS $ 5.95 $ 6.95 $ 5.95 $ 6.95 $ 6.95 $ 7.50 $ 9.95 $10.95 $1.50 $1.50 $1.50 $3.50 $3.50 $2.95 $9.95 $9.95 $1.50 $8.00 $8.80 $2.95 IDC CONNECTORS • TRANSIT AND EDGE PCB MOUNT HEADER R/ A IDC TRANSIT SOCKET IDC 10 IDC 16 IDC20 IDC26 IDC34 IDC40 IDC50 IDC 64 $2.65 $2.75 $2.75 $2.85 $2.95 $4.95 $5.25 $6.45 10 PIN 16 PIN 20 PIN 26 PIN 34 PIN SO PIN $3.50 $3.95 $4.50 $5.50 PCB MOUNT HEADER STR. IDC EDGE CON • 0.1" IDC lOWAY IDC 16WAY IDC26WAY IDC34WAY $2.50 $2.95 10PIN 16PIN 20 PIN 26 PIN 34 PIN SO PIN $2.60 $2.60 $2.85 $3.15 $2.50 $2.95 $3.50 $3.95 $4.50 $4.95 IEC POWER CONNECTORS • IEC MALE PANEL MOUNT • IEC MALE PANEL with FUSE • IEC LINE SOCKET * IEC LINE MALE $ 3.95 $ 5.95 $ 4.50 $ 6.35 MINI 'DIN' CONNECTORS' • PDM-3 * PDM-4 * PDM-5 * PDM-6 • PDM-7 • PDM-8 3 PIN 4 PIN 5 PIN 6 PIN 7 PIN 8 PIN $ 2.30 $ 2.30 $ 2.50 $ 2.50 $ 2.65 $ 2.65 . ; ; DAVID REID ELECTRONICS 127 York St. Sydney NSW 2000 Phone: (02) 267 1385 DISK DRIVE 4WAY POWER CONNECTOR only $3.95 Business Hours Mon - Fri 8.30 • 5.30 Thursday 8.30 - 7.00 Saturday 9.00 • 1.00 WELLER STATION 'WTCPS' SCOPE 'ECTIOL' STATION • 60WATTS • PTA 7 TIP SUPPLIED (370 C) • SPARE TIPS AVAILABLE 'ERSIN' SOLDER • 60WATTS • 200 C to 470 C(RJllY ADJUSTABLE) • LED TEMPERATURE READOUT $129.95 • • • • • • $208.00 0.71 mm 250g 0.71mm 500g 0.9mm 250g 0.9mm 500g 1.25mm 250g 1.25mm 500g ECONOMY SOLDER SUCKER $ 7.95 $15.00 $ 7.95 $15.00 $ 7.95 $15.00 ! • TEA.ON TIP • POWERRJL SUCTION $14.95 • HEATING and SUCTION WITH ONE TOOL sr··- M•"'·Tt a- ssl~ts PORTASOL'STANDARD'BUTANEIRON • COMPLETE WITH 2.4mm SOLDERING TIP * TEMPERATURE UP TO 400 C • BUTANE IRON * EQUIVALENT TO 10 to 60 Watts • COMPLETE WITH BLOW TORCH, HOT BLOW. HOT KNIFE & SOLDERING TIP MICRON VARIABLE IRON /' /.' ;,,;:~,.,/ 240 volt DE-SOLDERING IRON PORTASOL 'PRO' IRON KIT MICRON 20 WATI IRON ~f/4;.'.1,< >< $39.95 $79.95 DIAGONAL CUTIER NIBBLING TOOL AC/DC VOLTAGE PROBE • CUTTING CAPACITY: 1.2mm COPPER WIRE . 0.4mm STEEL WIRE HOBBY VICE • CUTS STEEL. ALUMINIUM OR PLASTIC * CAPACITY: 1mm (STEEL) 1.6mm (ALUMINIUM) • Detects AC or DC voltages without any hardwiring • Range: 50 - 500 volts AC. 3 - 220 volts DC • Alerts with both audible and visual signal • Clamps to any surface up to 25mm • Jaws open to 50mm $12.&0 LONG NOSE PUER • LENGTH 140mm $12.SO FLAT LONG NOSEPUER $19.95 7 • LENGTH 135mm AUTOMATIC WIRE STRIPPER CURVED LONG • AUTOMATICALLY ADJUSTS TO INSULATIONM'IRE DIAMETER $12.&0 ~~:~ :~S~~ WORKING IN CONRNED Sl'Af;ES • LENGTH 135mm $12.50 ' Cl ;)r $10.SO $22.95 CABLE TIE GUN $9.95 !1 ,''f.<,- ? t' AHi.EC 'SUPERTOOL' HEATSHRINK TUBING ARLEC CORDLESS DRILL '14' DRIVE A VERSATILE ELECTRIC TOOL DESIGNED FOR: POLISHING, CUTTING, ENGRAVING. DRILLING, SANDING, GRINDING, MILLING and ERASING. THE SUPERTOOL COMES COMPLETE with: 3 ENGRAVING BITS, 4 DRILL BITS, 1 WIRE BRUSH. 1 GRINDING BIT. 6 ERASER STICKS. 4 COllET CHUCKS. ALL HOUSED IN A HANDY CARRY CASE VARIOUS COLOURS AVAILABLE: BLACK, BI.UE, RED, CLEAR, GREEN, WHITE and YEllOW - 50% SHRINKAGE RECHARGEABLE TWO SPEED DRILL and SCREWDRIVER * TWO SPEED: 325rpm (DRILL). 150rpm (SCREWDRIVER) • FORWARD and REVERSE OPERATION * PILOT LIGHT ADDS LIGHT TO A DARK WORKPLACE • SUPPLIED WITH 3 DRILL ~.$: BITS and 4 SCREWDRIVER BITS ,o;~~ .AI • DRlllS into TIMBER. METAL ~ and HARDENED PLASTIC • 12 Months Warranty ONLY 82.50 ff REfllT&H ~----- 1.6mm 3.0mm 4.5mm 6.0mm DIA DIA. DIA. DIA. $2.20 $2.50 $3.00 $3.75 10.0mm 12.0mm 19.0mm 25.0mm DIA. DIA. DIA. DIA. $4.20 $4.70 $6.25 $9.35 All 1.2 mtr. LONG $65.00 HEATSHRINK GUN • 1600 Watt OUTPUT • DUAL TEMPERATURE SETTING • 400 C and 600 C• 12 Months Warranty $59.95 BREADBOARDS-WITH COMPONENT EDGE PLATE B-147P • 3620 Tie Points 4 Component Strips 7 Distribution Strips $83.50 TRANSFORMERS M285112.6volt CT C 150mA M2853 12.6 volt CT C 500mA M2155 6.3.7.5,B.5,9.5,12.6,15volt C 1A M21566,9. 12, 15wlt<at>2amp M667215, 17.5. 20. 24. 27.5, 30 volt C 1A POWER SUPPLY KITS 30 Volt 1 Amp Power Supply Kit $5.95 $7.95 $10.95 $17.95 $16.50 • Output variable between 3 and 30 volts • Output current: 0 to 1 amp (fully Variable) • Load regulation : Better than 0.2% form Oto Full Load * Output Ripple: Less than 2mV RMS $79.00 B-135P • 2420 Tie Points 3 Component Strips 5 Component Strips 50 Volt 5amp Power Supply Kit $50.00 B-123P - 1500 Tie Points 2 Component Strips 3 Distribution Strips $35.50 B-212P- 540 Tie Points 1 Component Strip 2 Disrtibution Strips • Output Voltage: 3 to 50 volts • Output Current: up to5 amps • Ri le less than OOmV - at Max. $21.00 P&P Rates Mail Orders: P.O. Box Q 103 Sydney NSW 2000 Fax: (02) 261 8905 $5-$25 $26-$50 $51+ $4 $6 $8 .-..e-l II $195.00 VISA PLASMA BALL DISPLAY LIGHTNING AT YOUR FINGERTIPS This comsic display will amaze you and your friends. Create beautiful swirling formations at the touch of your fingertips. It will also react to music via an internal microphone. • DIGI-SCALE will measure from 1 gram or 0.1 ounce up to 2kg or 4Ib 4 oz. • Convert from grams to ounces or ounces to grams using a selecta key • Various items can be individually weighed in the same container using the reset key • 240 volt ( plugpack not supplied) or battery operated • 12 month warranty $59.95 $150.00 ULTRA SON IC CLEANER PHONE BUG ALERT • Ideal for cleaning drafting pens. watches. photographic filters or even dentures *Green LED indicates all is O.K. flashing Red LED indicates someone else is on the line • No batteries required • Complete with Australian plug/socket for easy installation $189.00 This remote infra-red cordless headphone system allows you to listen to your favourite music without disturbing others in the room and without being tied to a cord. $34.95 m • temperature range -40" to +50"C • Presettable high/low alarm • Stainless steel probe with 1 metre cable • 1 second per 15 second sampling cycle $39.95 $99.00 NATIONAL LINEAR DATA BOOKS BLOOD PRESSURE MONITOR VOL 1, Voltage Regulators. OP-amps. Buffers. Voltage Comparators. Instrument amps. Surface Mount. VOL 2, Active Filters. Analog Switches./Multiplexers. A-D Converters. Sample and Hold. Temperature Sensors. Voltage References, Surface Mount VOL a, Audio Circuits. Radio Circuits. Video Circuits. Motion Control. Special Functions, Surface Mount. • Measuring: Oscillo-Metric method • Range: 0-300mmHg cuff pressure 40-150 pulse/min pulse rate • Accuracy ±BmmHg, pulse rate +5% of reading • Pressure build-up: squeeze bulb $119.00 $64.95 set of 3. LOADSPEAKERS 6.5" POLY WOOFER Input Power 30W rms Frequency Resp. 36Hz - 3,000Hz Sensitivity 1m/ lW - 87dB $24.00. 8 " POLY WOOFER DM-55 MIDRANGE nput Power 60W rms Frequency Resp. 450Hz - 5,000Hz Sensitivity 1m/1W-89dB 12" POLY WOOFER Input Power 100W rms Frequency Resp. 23Hz - 2,000Hz Sensitivity 1m/1W-93dB $85.00 Input Power 6fNV rms Frequency Resp. 33Hz - 3,000Hz Sensitivity 1m/lW - 90dB $39.95 • MS-501 3 WAY MINI SPEAKERS • Diecast aluminium cabinet • Complete with mounting brackets • Frequency Resp. 80Hz - 18kHz • 20 watts rms • Impedance 8 ohms $99.95 BVL MIXER with ECHO & EQUALISER • Output: 1.5V/ 0. 775V (selectable) • Frequency Response: 20Hz to 20kHz±1 dB • Distortion: Less than 0.05% • Echo: B.B.D. system • Delay Time: 30-200mS • Echo Repeat Control & Delay Time Control $379.00 . $57.95 - DT-20 TWEETER nput Power 30W rms Frequency Resp. 2.5kHz - 20,000Hz Sensitivity 1m/lW - 90dB $23.95 TELEPHONE ANSWERING MACHINE TA901 • Beeper - less remote • Single tape operation • Incoming call monitor * Vax $129.95 P&P Rates Mall Orders: P.O. Box 0103 Sydney NSW 2000 Fax: (02) 261 8905 $5-$25 $26-$50 $51+ $4 $6 $8 ■--II VISA BOOKSHELF Reference on op amp ICs IC Op-Amp Cookbook Third edition arithmic and · multiplier circuits, amplifiers (eg, instrumentation amplifiers), comparators, integrators and differentiators, and signal generation circuits (eg, oscillators and multivibrators). In short, if you don't already have an earlier edition, this book can be recommended to anyone who has a need to design with op amps. Copies are available from Dick Smith Electronics (Cat B-1240) and from Jaycar Electronics (Cat BS-0512). Audio projects for the enthusiast IC Op-Amp Cookbook, by Walter G. Jung. Third edition, published 1986 by Howard W Sams & Co, Indianapolis, USA. Soft covers, 218 x 138mm, 581 pages. ISBN O 672 22453 4. Price $39.95 This book was first published in 1974 and then again in 1980. This third edition has 100 more pages and so includes quite a few more devices than the earlier editions. Many of the circuits presented are based on device manufacturers' applications literature while some at least have been developed by the author who is a very prolific writer on electronics, particularly to do with circuitry for audio equipment. However, this text just does not cover audio topics but is a very comprehensive reference on the subject of modern operational amplifiers. It starts with a chapter on op amp basics and follows with chapters on the history and development of op amps and practical rules when using them. Following those there are 7 chapters devoted to op amp applications: voltage regulators, signal processing (eg, detectors, limiters, sample-and-hold), log- Enhanced Sound, 22 Electronics Projects for the Audiophile, by Richard Kaufman. Published 1988 by Tab Books, Inc, Blue Ridge Summit, Philadelphia, USA. Soft covers, 186 x 235mm, 170 pages. ISBN O 8306 9317 3. Price $19.95. Don't let the title of this book put you off. The projects in it are not highly complex designs seeking to get the very last drop of audio performance - almost the opposite, in fact. What are presented are quite basic circuits employing a few op amps at most. For example, there are a number of active filter circuits employing op amps. One is presented as an infrasonic (ie, very low frequency) filter to severely attenuate frequencies below 16Hz. The claimed rate of attenuation is 18dB/octave which is three times that of the typical rumble filter fitted to some stereo amplifiers. As another example of an active filter, there is a bass enhancing circuit intended to augment the low frequency response of sealed loudspeaker enclosures. The filter takes advantage of the fact that the response of a sealed enclosure falls at the rate of 6dB/octave and that you can apply a modest amount of boost below the cutoff. As well as presenting these circuits, the book also has a Basic computer listing whereby you can design your own filters. Computer listings are also provided for the design of sealed and vented loudspeaker enclosures, using Thiele-Small parameters. As well, there are number of designs for do-it-yourself antennas for FM reception, starting from the simple folded dipole and progressing up to a helical antenna. As an interesting sidelight, most of the circuits in the book are based on the TL072 although the author does nominate a number of equivalents. He makes the comment though that "some golden-eared audiophiles claim that the TL072 sounds better and is more 'musical' than any other op amp" . We think that is very interesting because in our experience, the TL072 has been more prone to supersonic oscillation than other types. So perhaps what the goldeneared types prefer is not perfection but that "something extra" in the form of supersonic oscillation. Makes you wonder, doesn't it? For readers who have some experience in electronics and are prepared to either design their own printed circuit boards or to wire them up on Veroboard or matrix board, this book is worth a look. At the price of $19.95 it is quite good buying. Our sample copy came from Dick Smith Electronics (Cat. B-3622). AUGUST 1989 61 Toss yer triple or quits! Triple or quits might sound like lengthening the odds a mite unreasonably over the conventional "double or quits" but then the the odds against a fault like this were pretty long anyway. As it happens, it wasn't one of my jobs, and for that I'm duly thankful. No, we are still in that foreign country across Bass Straight where my regular correspondent, J.L., seems to be encountering more weird ones than I am at the moment. And since "weirdos" are what these notes are all about, I'm happy to stand aside and let J.L. take the floor. Here's how he tells it. TV faults come in all shapes and sizes and the first step in solving any problem is to evaluate the symptoms. On this basis, one can then decide in what part of the set the trouble is most likely to lie. Some faults are so simple that only two or three easy tests are enough to identify the faulty component. Others take more time but in most of them the symptoms are a definite lead to the eventual cure. I was nearly going to say that some faults are so obscure that the symptoms are no help at all, but that's not really true. In this story, the symptoms led me on several wild goose chases but in the end there was one symptom that did lead the way. The unit was a Kriesler 660-2iA colour TV set fitted with a 59-3 chassis. It is about 10 years old and is one of those magnificent examples of the cabinet maker's art for which Kriesler was famous. The 660-21A is a double ended console on a solid, fluted plinth. The cabinet is built of 19mm particle board faced with real wood veneer. It weighs a ton but is a fine piece of furniture which the family hopes never to part with. (The owner runs the local fishand-chip shop and he values this set largely because, he claims, it's the only one he knows of that can speak Greek without a Japanese accent! TETIA TV TIP Philips K9 Symptom: Repeated fai lure of line output transistor. True cause of the trouble was not revealed until the normal line output transistor was replaced with an extra high voltage high current type transistor. Cure: C446 (.01 µF 1500V) across line output transistor gone low value. If this cap goes open circuit it can cause puncturing of the picture tube by the generation of excessive EHT. In this case the 62 SILICON CHIP trouble was only a partial breakdown and was eventually exposed by brilliant flashing around the tube base spark gaps and discharges from under the ultor cap. The EHT must have been well over 40kV! TETIA I V Tip is supplied by the Tasmanian branch of The Electronic Technicians' Institute of Australia. Contact Jim Lawler, 16 Adina St, Geilston Bay, Tasmania 7015. Seeing that the set spends most of its time playing Greek videos, or showing Greek programs from SBS, I guess it's just as well it has no such bias!) The owner complained of irregular lines across the screen, or sometimes shaking verticals. The fault was intermittent, sometimes disappearing for hours at a time, but it could usually be relied on to appear at switch on. The way he described it, it sounded like line tearing, a symptom often associated with faulty horizontal drive and just a whisker away from destruction of the horizontal output transistor. Fish & chips I called to look at it on what turned out to be the hottest day of the year. It was 36° outside and inside was not made any more tolerable by the smell of cooking fish and chips from the shop out front. The fault is not easy to describe. The "lines" seemed to be a form of line pairing, where the vertical scan stops working for a millisecond or two, only to catch up again when the fault passes. The shaking looked like very irregular sync, with subsequent lines starting anything from 5µs early to 5µs late. At other times, the vertical lines assumed a regular sinuous wriggle from top to bottom of the screen, like hum bars only faster. There wasn't the slightest uniformity in the symptoms and the fault could have been in any of half a dozen parts of the set. As an indication of how difficult this job was going to be, the shaking stopped after half an hour or so and nothing would induce it to start again. However, one other symptom now appeared. I could see a small, erratic variation in the width of the picture and found that the width control (R691) had no effect. The width is controlled by a BD236 transistor (TR697) and I have found these exhibiting funny faults at times. So I changed it, only to bring back the shakes which masked any change in the function of the width circuitry. I spent an hour looking for dry joints or similar problems but nothing showed up. By this time I'd had enough. The atmosphere was so hot and overpowering that I couldn't think straight and I resolved to get the set back to my workshop where I could work in greater comfort. But the Kriesler is so bulky that I couldn't get it into my small Mazda van. We had to wait until the owner's nephew arrived with his big Chevrolet panelvan. Once set up in my workshop the Kriesler was a lot easier to work on. The first thing I did was to hang my oscilloscope on to the horizontal driver transistor and the horizontal output transformer. Unfortunately, this gave me no joy at all. Both the drive ~nd output were rock steady, during both the shaking phase and varying width phase. The width control was still inoperative so I checked the components around it and its two associated transistors, one of which I had already changed. This proved quite fruitful because both R692 (56k11) and R695 (39k11) had gone high. Also, C696, a lµF 50V electro looked sick. It too was changed but none of this made the width control work. By now I had been all over the width control network with an ohmmeter, my capacitance meter and the oscilloscope. These instruments had told me nothing, so it was back to fundamentals - and a voltmeter is about as fundamental as you can get. Disappearing volts This proved to be the way to go because the emitter of TR697, a BD236, and the collector of TR695, a BC547, were both around 8 volts, instead of the 12 volts specified. The supply rails to both transistors were exactly as specified and, in the absence of faulty components, the trouble had to be in the bias supply, a - 25V rail feeding the width control pot. Sure enough, the rail was reading only about - 1V and the scope showed it to be incredibly spikey . with horizontal frequency pulses. The cause was an open circuit lOOµF 40V bypass capacitor (C810) and replacing this brought the rail back to normal and restored the full operation of the width control. It also restored full operation to the "Straight Outer Vert. Lines" control (R686, 2.2k0) which had had only limited action before the rail voltage was corrected. I now had full control of width and geometry but all of this had done nothing to correct the shaking or pulsing width. Only one thing did show up and I'm not sure of its significance in the context of this story. I happened to touch R785, (a 56011 5W spring type safety resistor in parallel with the horizontal linearity coil) and the picture broke up into crazy diagonal lines. I had serviced this once before when the resistor opened for no apparent reason. Now, touching either end of the resistor with a screwdriver produced the crazy patterns. Suspecting a fault in the resistor, I removed it and cleaned and resoldered the spring. None of this made any difference to the symptoms and the scope showed the waveforms at each end of the resistor to be rock steady. The only possible improvement was that, from this point on, I didn't see the "line pairing" again. The shakes and wriggles continued but the lines across the screen had gone. Next, I went to the small signals board to look at the video signal, in the hope that there might be some irregularity in the sync level that could explain the problem. But I found nothing. The sync separator is in one of two chips on the horizontal control board. I replaced both chips and went very carefully over the board, looking for dry joints, dodgy electros, or anything else that might play up with the horizontal drive. I even removed and checked the AUGUST 1989 63 been able to measure anything, or observe anything on the scope, that was in any way out of place. For the time being, I ignored the shaking and wriggling and concentrated on the size variation. This had to involve a source which affected the horizontal and vertical circuits equally. There were only two such possible sources: the power supply and the picture tube. I had already eliminated the power supply. Its output was rocksteady without the slightest trace of ripple. So if it wasn't the power supply, it had to be associated with the picture tube. There is only one picture tube mechanism that I know of that allows the size of the picture to change; the EHT voltage. It will bloom if the EHT drops and shrink if the EHT is too high. A tiny picture results if the capacitor across the horizontal output transistor fails and allows the EHT to go sky-high. This is fairly common in some Philips sets and often results in the destruction of the picture tube. My problem was how to look at the EHT with the tools I had on hand. I had already found that the input to the horizontal output transformer was rock steady, indicating that the trouble could be either in the transformer itself or in the tripler. The ideal place to look for trouble in this area would have been the input to the tripler. An unsteady BkV would have placed suspicion on the transformer or perhaps the tripler. But BkV at 15kHz is not easy to observe with any degree of accuracy. I then turned to the next most accessible measuring point. This is the focus voltage output and is only one high-voltage diode away from the BkV input. But when I used a· high voltage probe to measure the focus voltage, I realised that it wasn't going to be so easy. Trying to see small variations around an BkV reading on a 30kV full scale meter was asking a bit much of both the meter and my tired old eyes. The breakthrough All in a flash Then I saw something that I should have noticed hours earlier. Not only was the width varying slightly but so also was the height. This opened up a whole new range of possibilities. Just then I had a flash of inspiration - I didn't have to read the full BkV focus supply. Because the BkV is applied to a resistive divider chain, this would give me several lower voltages, each of which SERVICEMAN'S LOG -CTD D759 8Y206 '-~ ~ 13Y206 To SK704 Pin 3 --l C751 •01 C807 3900 ~~~ To SK704 Pin 6 689 82~ t6S7 :684 R823 / R825 30V ~:::* Fig.1: the relevant circuitry of the Kriesler 59-3 TV receiver. The width control, R691, is at bottom centre, while the focus control network, R760, R761, R762 and R763, is at the top, above the tripler. horizontal driver transformer and replaced the horizontal drive transistor, but there was still no improvement. By . this time I was getting desperate. Something was causing the picture to break up and something was making the width vary. I had no idea whether this was two faults or two manifestations of the same fault. I hadn't 64 SILICON CHIP would be an exact percentage of the full focus voltage. In greater detail, there is an 8.2MO resistor (R760) from the BkV line to the focus pot (R761, 2.7MO), then two 5.lMO resistors, R762 and 763, in series to chassis. The junction of the two latter resistors is at about 2kV and this is within the range of my oscilloscope. In no time at all I had a trace on the screen showing part of the focus voltage popping about between 1.9 and 2kV. And, by implication, the EHT was also jumping about, probably between 25kV and 26kV. Of course, this still didn't tell me whether it was the transformer or the tripler that was faulty but, as the tripler was the easiest part to substitute, it was my first choice. It took only five minutes to fit a new tripler and at the first switch on I had a rock-steady picture. Although this was the best result I'd had since starting the job, I wasn't prepared to accept it as finished because, at this point, I had only cured the shrinking pro. blem. The shaking and wriggling were not necessarily explained by a faulty tripler and might well have indicated another fault waiting to show up later. I put the set through a dozen onoff cycles and let it run for several hours but there was no sign of any more trouble. Then, to make sure, I replaced the original tripler. This removed all doubt because the shaking, wriggling, shrinking picture was back with all its annoying features. So it was the tripler after all, even if this didn't explain all the symptoms. Over the years I have replaced hundreds of faulty triplers and almost invariably these have been for internal short circuits. A very few have gone open circuit and some have burst irreparably from their plastic cases. I've even heard of, but never seen, a tripler that was intermittent go and no-go. But I've never seen one that was sort of intermittent but not quite! The first story started while I was briefly absent from the shop, having left it in charge of my secretary who comes in from time to time to help straighten out my paper work. She took a phone call from a potential customer, requesting that I come to their home and look at their TV set. Acting on my instructions she advised the caller that it would be better if he could bring the set in (I'm trying to cut down on house calls to save costs). The caller agreed and, a couple of hours later, a car pulled up outside the shop, with a man and a woman in it and a TV set on the back seat. As I walked out to the car I could see what appeared to be the moulded back sitting on top of the cabinet. In answer to my unasked question, the lady explained that they had had some difficulty in getting the set into the car, so they had removed the back to make it easier. Then she added, "We got it in OK, but there was a funny hissing noise as we settled it on the seat". Well, no prizes for guessing. As I moved in for a closer look I noticed another strange aspect. The cabinet, basically of chipboard, had no veneer of other covering of any kind; it was simply bare chipboard! I also identified the set and realised that it was quite long in the tooth. It was a 54cm Mitsubishi and would have been between 12 and 13 years old. It was one of the early sets on the market after the introduction of colour. But all this was rather academic. Tipping the cabinet forward on the seat I showed the couple where the neck of the tube had been broken; it was just in front of the neckboard, the base section and the neckboard having come away as a unit. That was when I pointed the way to the tip. Well, not in so many brutal words but, as I pointed out to them, there was little point in trying to salvage the situation. Supplying and fitting a new tube - with no glass allowance - would cost at least $300, and perhaps as much as That way to the tip as $350, depending on the current After that story the best I can tube price. And that was without considercome up with is rather puny by · comparison but it does highlight ing the original fault which started the whole sequence. I had to warn some customer problems. FIX-A-KIT Kit Repairs - $1 5 per hour. Normal Rate - $35 per hour. No charge for kits that can't be repaired . 3 month Warranty on repairs. Construction - fixed or hourly 1 2 Month Warranty on Manufactured Kits. Custom Designing, Manufacturing, Large or Small Quantitites. HYCAL INSTRUMENTS Design, Manufacture, Repair of Electronic Equipment. (02) 633 5897 Unit 4, 62 Great Western Highway, Parramatta, NSW 2150. Trading hours: 8am to 3pm Monday to Friday. D.DAUNER ELECTRONIC COMPONENTS WE STOCK A WIDE RANGE OF ELECTRONIC PARTS for • Development • Repair • Radio Amateur • Industrial Electronic • Analog and Digital WHILE STOCKS LAST * THE FAMOUS TR-DIP METER (as featured May '89) $98.00 * CAO-VALVE 3ACP2A $45 .00 * PHILIPS IA-IMAGE CONVERTEH VALVE XX1080 $45.00 (For use in infrared sight experiment systems) Come and see. Showroom: 51 Georges Crescent, Georges Hall, NSW 2198 (Behl■d Calte1 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. AUGUST 1989 65 SERVICEMAN'S LOG -CTD them that it could add another $100, or even more, to the overall cost. Fortunately, they seemed to accept the news philosophically. The lady simply shrugged her shoulders and said, "Its rather bad news, isn't it". And that about summed it up. But one final point. If a TV set has to be carried on the back seat of a car, it should always be loaded with the tube face towards the back of the seat; the weight distribution is far better that way. And, of course, a set should never be transported with the rear cover removed. Leaky cat And while on the subject of 66 SILICON CHIP unhappy endings, here's one about a video recorder. It was a Sharp Model 9300, about five years old, and was left at the shop while I was absent. There was little information with it; just a rather cryptic message, "It doesn't go - fix it". Knowing the owner, who is a rather aggressive type, this message didn't surprise me. When I switched it on its static behaviour was rather erratic and I hesitated to load a tape into it, lest a mechanical fault should chew up a good tape. Instead I undid the four screws and removed the top cover to reveal the copper side of the main board. And that was as far as I needed to go. Near the rear centre of the board was a patch of corrosion about 70mm in diameter and, to the left of this, a smaller patch aboout the size of a 20c piece. Something had obviously been spilt on top of the machine. Exactly what was a puzzle. It is not unusual for drinks to be spilt on VCRs - anything from coffee to beer - and, while they all make a mess, they seldom cause corrosion. I moved in for a closer look and made what modern jargon writers would probably refer to as "olfactory contact" - I could smell it. It was strong, pungent, and unmistakable - feline urine! I backed off quick smart but not before I'd seen enough of the damage to know that it was beyond repair. A whole group of tracks had been eaten through and I could only speculate as to what effect the contamination had had on the insulating properties of the base material. As to what other damage had been caused, that was anyone's guess. I rang the owner and gave him the bad news. He didn't take it too well and obviously wasn't prepared to take my word for it. So I suggested he come to the shop and see for himself which he did, but even then he refused to accept the situation; as far as he was concerned it was simply a matter of patching up a few tracks. I pointed out that there were more than a "few" tracks, that they were very close together, and that repairing them would be a big job. I put a tentative price of $100 on the job and that was not taking into account any other faults which might show up when the tracks were repaired, such as the central microprocessor IC. This would cost around $70, plus the cost of fitting. And there was no guarantee that the repair would be long lasting. Finally, he went through the motions of accepting my advice but he went off muttering something to the effect that he didn't believe the cat was to blame. Well, that's something between him and the puddy tat. Why do some cats do this? This is not the first such incident I have encountered, though it was one of the worst. I assume that it is the gentle warmth that attracts the moggie in the first place; beyond that the reader's imagination can probably fill in the gaps. ~ WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR C ULTRASONIC CLEANER CTORS ~ PCB Mount with Ejectors ~ Type cc 10Way 14Way 16Way 20Way 26Way 34Way 40Way SO Way 60Way 0 ll.. Cl 0 ~ ~ i5 cc 0 ll.. Cl 0 ~ ~ iS cc 0 ll.. 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Ideal for situations where the mains is 'sagging' or you want to check the effects of mains variations on equipment. FrH •tsndlng 7amps at up to 270V SA at up to 250V $174.88 $148.95 Panel Type 1.2A at up to 250V $91.20 2.5A at up to 250V $114.00 Other a/zn to •peclal order Have you priced DMM's lately? Check the new LOWER prices on these three Goldstar DMMs. DM6135 Auto ranging 10Aac/dc $69.00 DM6235 as above but with Memory function and Range Hold $79.00 DM6335 as above but with Data Hold $89.00 ~ GENDER BENDERS AD SWITCHES e Benders ~ :i:(..) cc 0 ll.. 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P.O. Box 671, Lane Cove N.S.W. 2066 ~ .,, ~ 0 Telephone: (02) 428 4111 Fax: (02) 428 5198. C') Cl 0 8.30am to 5.00pm Monday to Friday, 8.30am to 12 noon Saturday. Mail Orders add $5.00 to cover postal charges. Next day delivery in Sydney add $5.00. ~ I.I.. ~ ::i: All prices INCLUDE sales tax. Tax exemption certificates accepted if line value exceeds $10.00. . BANKCARD, MASTERCARD, VISA, CHEQUES OR CASH CHEERFULLY ACCEPTED AMATEUR RADIO By GARRY CHATT, VK2YBX Clean up your 2-metre reception with this GaAsFet preamplifier By adding this easy-to-build preamplifier at your antenna terminals, you can greatly improve your 2-metre reception. It uses a readily available GaAsFet transistor and is built into a small shielded case fabricated from double-sided circuit board material. One of the major contributing factors to VHF system performance is the receiver's noise figure. Put simply, the lower the receiver's noise figure, the greater its ability to receive weak signals. This is something that interests all amateur operators. In fact the noise figure of a preamplifier stage at the receiving end is far more important than the gain of the preamplifier. Decreasing the noise level will result in an improved signal to noise ratio and therefore better signal readability. But simply adding more gain without any regard for the overall noise figure simply gives more signal and more noise - ie, there will be no improvement in the signal to noise ratio. A typical 2-metre amateur receiver will have a noise figure of 2dB or less. By adding this GaAsFet preamplifier (and thus improving the noise figure to less than ldB), an improvement of several dB in the signal to noise ratio can be obtained. This can mean the difference between a scratchy signal and a signal that drives the receiver to full limiting. . . . - - - - - - - + 9-12V C5 .001I F29 .,. FERRITE 01 3SK121 G C1 47 INPUT FROM~ · PF ANTENNA 0-:--1 R2 2700 ~AJ D 61 S CT2 _ _ _ _ _ 20-90pF L1 4.~~~ 1-:-0 OUTPUT TD RECEIVER C3 R1 .001I 1800 ":" Circuit details "':" L1, L2 : 7T, 22SWG TINNED COPPER WIRE 6mm, ID 22mm LONG. L1 TAPPED AT D.5T, L2 TAPPED AT 2T GaAsFET 2-METRE PREAMPLIFIER Fig.1: the circuit is built around a 3SK121 GaAsFet (Ql). L1 and CTl form the input tuned circuit while L2 and CT2 form the output tuned circuit. The ferrite bead is there to stop parasitic oscillation. 68 SILICON CHIP It's not simply a matter of plugging the preamplifier directly into the receiver's antenna socket, though. Certainly this will improve the receiver's noise figure but it will not minimise the overall system noise. This is because the feeder loss between the antenna and the receiver contributes to the degradation of system performance. Conversely, by installing the preamplifier at the antenna terminals, the feeder loss is overcome by the preamplifier's gain. The overall noise figure of the system is then set by the active device in the preamplifier. The preamplifier described here can be built quite inexpensively. Note that it is intended for use as a receiver preamplifier only and does not contain the necessary RF switching circuitry for transceiver applications. It is designed for use with 2-metre receivers, monitoring beacons, repeaters and for the reception of polar orbiting satellites. Do not use the circuit in a transceiver application. If you do, you'll blow the circuit as soon as you hit the PTT (press-to-talk) switch. OK, let's now take a look at the circuit (Fig.1). It's really very simple and is based on a Toshiba GaAsFet, the 3SK121 (Ql). Incidentally, "GaAsFet" is an abbreviation of "Gallium Arsenide Field Effect Transistor", a hot device when low noise figure and very high frequency operation are required. GaAsFets, by the way, have bet- ,..-------------• 1 AMATEUR RADIO Hobbyists communicating world wide using state-of-the-art electronics. Are you a radio amateur but not a member of the WIA? Do you know what you are missing? Do you like using VHF/ UHF repeaters? Enjoy working DX? I Want to preserve your bands? I The preamp circuitry is built into a shielded case made from double sided printed circuit board. Keep all component leads as short as possible and don't forget the wire link between the gate 1 and source leads of the GaAsFet (see Fig.4). ter noise figures than the once popular Mosfets which were in vogue in the late 1970s, and used then by many amateurs. Input tuning and matching is achieved using trimmer capacitor CT1 and inductor 11, while the output is tuned by CT2 and 12. Capacitor Cl (4.7pF) couples the input signal to gate 1 (Gl) of the 3SK121 which is self biased by Rl (1800) in the source circuit. The amplified output signal appears at the drain of Ql and is coupled to the output via the second tuned circuit (CT2 and 12) and C6. The ferrite bead (Fl) in the drain circuit of Ql is included to prevent parasitic oscillation. In practice, it is simply slipped over the lead of the transistor. Power for the circuit can be derived from any 9-12V source (eg, a plugpack supply) and is regulated and filtered by 6.2V zener diode ZDl, R2, C4 and C5. Construction As can be seen from the accompanying photo, the circuit is built into a shielded case which is made from blank double sided circuit board. The advantage of this material is that it is very easy to work using simple hand tools. Actually, our first prototype was assembled on a piece of single sided circuit board, without any enclosure. However, better performance can be obtained by using double sided circuit board to completely shield the preamplifier circuit. If the unit subsequently requires repair, the "case" can be easily taken apart using a soldering iron and some desoldering wick. The first step in the construction is to ensure that the blank circuit PARTS LIST 2 chassis-mount BNC sockets 1 piece of blank double-sided PC board 2 5.2-30pF trimmer capacitors (Jaycar Cat. RV5704) 1 40cm length of 22SWG tinned copper wire 1 F29 ferrite bead 1 3SK121 GaAsFet (Q1 DSE Cat. Z 1845) 1 6.2V 400mW zener diode (ZD1) 4 .001 µ,F feedthrough capacitors (DSE Cat. R2851) 2 4. 7pF ceramic capacitors 1 2700 ½W resistor 1 1800 ¼ W resistor Join the WIA - the oldest and most experienced radio society in the world - always at the forefront of radio communications for hobbyists. Receive AMATEUR RADIO, the monthly magazine for members of the WIA, full of news of DX, clubs, satellites, technical articles and lots more. Other WIA services include: • A world wide QSL card service • Weekly news broadcasts • Classes for all grades of amateur licences • Correspondence lessons I available I • Meetings, contests, field days I • Representation for radio I amateurs at Government level I I Learn more about the WIA and I Amateur Radio : Forward this coupon, or write to: WIA EXECUTIVE OFFICE I P.O. BOX300 I CAULFIELD SOUTH I VICTORIA 3162 I Reglst•ed address: 3/1 wlllonl Road I C.lfleld North, 3111 I Please send aWIA information package to: : NAME: ...............................·............................. I ADDRESS: ...................................................... I 1........................................................................ I I ................................... POSTCODE ................. 1.-------------~ EO03S 1 IJ ------------ SIDE PlEL 1 ~S IDEP_ , _ = "' BASE BOARD 1- POWER FEED PANEL SIDE PANEL 2 SIDE PANEL 2 N 58 -1 INPUT AND OUTPUT BOARDS .___ · -=-($--+--A LID -. - - J J J 50 54 POWER FEED BOARD 10 7 J -J DIVIDER BOARD ·q)~~ ·%r- . 7 ~ ] B le 16 33 HOLES A : 9.5 DIA B: 3 DIA. C: 2 DIA. 45 DIMENSIONS IN MILLIMETRES Fig.2: here are the dimensions and drilling details for the various panels. The panels are made from double-sided fibreglass circuit board. board is clean enough to take good solder joints. If the circuit board is tarnished, it can be cleaned using a soap impregnated steel wool pad and warm water. Fig.2 shows the dimensions and drilling details for the various panels. The circuit board can be cut using a guillotine, a fine hacksaw, or by scoring the edges using a sharp utility knife. In the latter case, you will have to make several deep scores on each side of the board before it can be broken in a vyce. Fibreglass circuit board is the only type to use as Bakelite or phenolic based circuit boards tend to crack in the wrong places. The input and output panels are easily assembled by mounting the BNC sockets and tightening their respective nuts. Ensure that these are tight as it is impossible to tighten them further after final assembly (ie, after the case has 70 SILICON CHIP 4 ~ ] ·--·-i-· "' ____,__10 54 -ouTPUT PANEL -INPUT PANEL I 54 -DIVIDER PANEL been fully enclosed). The divider panel is used to separate the input and output circuits. It requires three holes as shown in Fig.2: two 3mm holes to accept two .001µF feedthrough capacitors (which act as bypass capacitors in this application), and a third to allow the Gate 1 lead to enter the input cavity and connect to the input inductor (Ll). After drilling, check to ensure that there are no fragments of copper foil around the holes which could cause a short circuit. Feedthrough capacitors have been used in this application because they can be mounted close to the GaAsFet leads and because they have minimum lead length. This allows bypassing right at the gate 2 and source terminals, thus eliminating the possibility of parasitic oscillation. Because we do not require the Fig.3: this is how the case goes together. The panels should be installed on the baseboard in the order outlined in the test. "feedthrough" feature here, the capacitor leads which protrude into the input cavity are cut off to prevent short circuits (see Fig.4). Once the feedthrough capacitors have been soldered in place, the divider board can soldered to the baseboard. Fig.3 shows the details. Use a pencil to mark out the baseboard, then position the divider panel and make a single solder tack. Adjust the board as necessary by reheating the joint (make sure it is vertical). Once you are satisfied with the position, run solder fillets right along the join lines on both sides of the divider panel. The next step is to mount the input and output trimmer capacitors (CT1 and CT2). These should be positioned as accurately as possible so that their adjustment screws will later line up with the access holes drilled through the top · cover. Orient the two trimmers as shown in the wiring diagram (Fig.4), then solder the two earth pins of each trimmer to the baseboard. The remaining terminals of trimmers CT1 and CT2 are soldered to the input and output coils respectively. Winding the coils 11 and 12 are wound using 7 turns of 22 SWG tinned copper wire on a 6mm former (eg, a drill bit or a pencil). Each coil should then be air spaced over 22mm. The input coil is connected between CT1 and ground (on the baseboard). Be sure to allow a gap of 2mm or so between the coil and the divider panel to ensure that there are no shorts. This done, the GaAsFet can be mounted by feeding the gate 1 lead through the remain- INPUT FROM ANTENNA OUTPUT TO RECEIVER + 9·12V - Fig.4: parts layout inside the case. Try to position the two trimmer capacitors (CT1 & CT2) as accurately as possible so that they will line up with the holes in the lid. C2, C3, C4 and C5 are .001µF feedthrough capacitors. to the base and di lider panel (see Fig.3). The remaining components can now be installed. Connect Ql 's drain lead to the output trimmer (CT2) via the ferrite bead, then fit the 1800 bias resistor, the output inductor, and the 470pF input and output coupling capacitors (Cl and C6). Cl should be connected 0.75 turns from the trimmer end of 11, while C6 should be connected 2 turns from the trimmer end of 12. Note that the gate 1 and source leads of Q1 must be tied together using a wire link. The external power leads should also be connected to the power-feed panel at this stage (red for positive, black for negative). The side panels and the input and output boards can now be tack soldered in place. A pair of tweezers can be used to hold Cl and C6 when soldering them to the input and output sockets. Test & alignment The power feed panel (at the end of the penJ carries resistor R2 (2700), zener diode ZD1 and two .001µF feedthrough capacitors C4 and C5. It should be accurately positioned on the baseboard as indicated in Fig.3. ing hole in the divider panel and soldering it to 11. Make this connection about 0.5 turns away from CT1. Now move to the other side of the divider panel and solder the gate 2 and source leads to the two feedthrough capacitors. Be sure to trim off any excess lead length after soldering. Next, the remaining two .00lµF feedthrough capacitors can be installed on the power-feed panel. Only one capacitor is used in the feedthrough mode so it will be necessary to cut off one of the leads as indicated in Fig.4. Install the 2200 resistor and ZDl, then mount the power-feed panel by soldering it Specifications Gain .... ....... .. .. .. ....... ...... .. 18d8 Noise factor .. ... 0.8d8 (146MHz) Bandwidth .......... ......... ... . 1 MHz Supply voltage ..... ...... 9-1 2V DC Current consumption .. .. .. .. 20rnA The unit should be powered from a 9-12V DC source and should draw about 20mA. Check that the voltage at the anode of D1 sits at about 6.2V. Because this is a receive only preamplifier, it should not be connected to a transceiver unless the microphone is disconnected. This step will prevent any accidental transmissions and subsequent damage to the unit. The most suitable signal source to use for alignment, apart from a signal generator, is your local 2-metre repeater or beacon. There are only two adjustments to be made - CT1 and CT2. Adjust these for maximum signal strength. Note that it may be necessary to listen to a weak repeater, cir to add an inline RF attenuator between the antenna and the preamplifier, in order to adjust the preamplifier for maximim gain. Once the alignment is complete, the lid can be soldered into place and CTl and CT6 readjusted for best performance. Note that some readjustment will be necessarv to compensate for the added capacitance of the lid. Solder all sides of the lid to the input, output and side panels to ensure that there is no instability. ~ AUGUST 1989 71 PHUNEORDER TOLL FREE ALTRONICS 008 999 007 Look at the really special bargains we've got this month - the wire specials alone will save computer and telephone installers a fortune. And look at the great deal we've got on PCB's - it's a long time since they were this price. .. Then there're speakers for as low as 99cents! You've waited for it;. the fabulous Ultrasonic Cleaner is going for $25.00 less this month only. 1AA Ni Cads by MICRON .c,. ~==;.;;;;;;;;;;;;;;~ I$3.50 ea, or save a fortune by buying 1 Thermalloy T03 HEATSINK """ 0 0 en en en co 0 0 en -CJz 0 for as little as I in bulk 10 for $30.00 IPremium grade - good for up to ; - / 1GHz Digital Frequency Meter (SeeSCNov'87Jan'88) ... ... .,, I I t::• I SAVE $30.00 1,000 recharges. ., I 1LS_ 5020 500Ah _AA _1.2V __ _ _ _ _ _ _ ..J 70 cents/ • H 0503 Were $1.50ea NOW ONLY 80 cents each! 10 up price 70 cents a: ~ Earns its tort hunder<h of times over in cleaning connectors, PCB 's, switches, jewellery, gluses, watches, drafting pcm, etc. < Awarded the Good Product Design Award for w w Pin Point ULTRASONIC CLEANER CETDC in 1987 ...J ...J FREE 008 999 007 Woo't 1aatch or damage~ U9CS ordinary tap water and acatc:1 milliom of super-penetrating bubbles. Hospital test. ahow that lntruonic cleaning produces better re1ults safer than conventional methods . a: LL~RIIII~ TOLL In Just 3 minutes you will be amaud al the difference! ~ Linear a: Data & ~ Applia: cations <at> Set z 0 :I: A 0100 TOP VALUE AT $199.00, ONLY $174.00 THIS MONTH SAVE cl 0 0 00 $25.00! co co co 0 0 D.. ~ (See E cctronics Austnlia 's amazinA new sub-woofer project Aug/Sep '89 8 Ohm Impedance . O- 3000Hz +/-Sliz) 6 112" Polypropylene 1 1Watt 87db (+/-2db) 30Watt RMS C 3055 $29 .95 50WMax. Top Value FffijUCllC~onse You get Voi1. 1,2. & 3 and the, mrntlli4a.Y m:JIICll.T1008TAIN, lata::11t printing of National ocmicondw:ta Linear Applicatiau. ( Plcuc nou, that the Linoar Applicatiom can't be IO!d acporau:ly) 4 books normally $24.00 each • $96.00 Value tor only $79.95 the set of 4. Resonant uency 36Hz ( Sensitivity Voice Coil 25mm PHONEORDER TOLL FREE ALTRONICS 008 999 007 PHONEORDER TOLL FREE ALTRONrcs--oua--9-99 -001 - SCOOP PURCHASE! RACK CASES Put your projects on display In a really professional setting FEATURES: • Beautifully aafted to give your equipment a really first class appearance. • Aluminium consttuction with removable top and bottcxn .tccl covcr pancl1. • All dimensions ccnfonn to the International Stmdard • Subtle Grey or Hondsome Black finish.• Ventilated lid• Deluxe finish front panel• Individually cartoned• Supplied in flat pack fonn - euily usembled in minutes Dimemions: A = Front depth, B = Mounting bolt centres, C = Internal chassis depth, D = 254mm in all cases. Finish Cat.No. H0401 H0402 H0403 H0411 H0412 H04!3 GREY GREY GREY BLACK BLACK BLACK A 44 88 132 44 88 132 C NORMALLY 38 $59.95 82 $69.95 $85.00 126 38 $59.95 82 $79.95 126 $89.95 B 34 57 89 34 57 89 THIS MONTH $5S.OO $6S.OO $80.00 SSS.00 $7S.OO $8S.OO SAVE $4.95 $4.9S 0 0 0) 0) 0) GREY FINISH NORMALLY THIS MONTH H0421 H0422 H 0423 $11.95 $14.95 $18.95 $10.99 44mm 88mm 132mm $13.SO $17.S0 Calling all PCB Makers $4,95 $4.9S $4.95 .- - .- BLACK FINISH NORMALLY THIS MONTH H0426 H 04Z7 H0428 $11.95 $21.95 $29.95 $10.95 $19.95 44mm 88mm 132mm 527.SO 3 - 50 Volts at up to 5 Amps ( Ea May' 85) CX) en z 0 a: "'- LABORATORY POWER SUPPLY Spees: 1 Output Voltage - 3.50 Volts • Output Current up to 5 Amps (max. 175W) • Hosting outputs isolated from ground • Ripple less than 90mV p-p at max. Employs Dual Meters• no switching from one to the other. 0 0 0 ON BLANK PCB MATERIAL $S.00 BLANK RACK PANELS EXCELLENT VALUE l'- --- --- ----~-~ We have just purchased a truckload of blank phenolic PCB board, both single-sided and double-sided. Typical sizes are 150mm x 400mm to 200mm x 500mm ALL BRAND NEW STOCK Single-sided PCB 1-9 Size I 3l0x185mm $2.00 Size 2 405x170mm $2.00 Size 3 505x90mm $1.70 l0up $1.70 $1.70 $1.50 Dou hie-sided PCB IOup $3.00 Size 505x205mm $3.50 TELEPHONE OFF-HOOK INDICATION <( W W m m Fixed outputJ independent of variable main output LL _ CJ:: .,._ K _____________ 3302 $14.50 > !:i l] ..J MEGGER METER See EA AprlVMay 89 FREQUENCY ..J Checb electrical wiring and appliance• for insulation breakdown. Insulation breakdown can be detennined by the uae ofthil dual range megohm meter. Ideally suited for t!Ecking breakdown in electric.al wiring. appliances transformers, automotive gcneraton and alternators etc. Breakdown can be mcuured at either 300V or 1000V depending on the required situation. w C a: Woa,ld 1wil •I.ChwMUU or l•cl111.ieiluu work NII, tool box or work IH•cll. 0 w REAL VALUE z 0 METER (EA May '88) Flt this Into your toolbox for only $99.00/ 50MHz in 5 l'&IlgeS, Features high input impedance, o~0ow LED indicator, kHz and MHz LED indicators. Uoe where 2 or 3 phoooa arc =-cted <m the oac line. When ~ cxtcmioo ii in me LID will lluh in each of the othcrextcmiooa. No e~tcrnal 1t1ppy required • runs off phooo line. One module r,:quired fer each phone. K 1400 i $79.00 co co co 0 D. POWERHOUSE 600W Get 240V AC Mains Power from your battery with these handy Inverter kit sets Many combinations to chooN from: 300 WATT INVERTER INVERTER WITH AUTO START (See BA Dec'l7) 0peraa frODl 12V Car B-,. 1 Auto Start n - paws from your l a ~ only wlai opplianco ii pluged in and '"tumDd oa• ic, boi.y can be loft pormmondy comctliod if requiled. e Voltap RogulalDd Cummt Rogulalocl Cu=nt Ovcrlood unit lllllf limill Toil inwrtcr hu the capacity to produce 600 waltl of maim power which will nm a fan!Utit 11T&Y of appliances. Ideally .uimd to running power tool ■, lighting (including Ouros) e!Otlrit mot<n Ind much mcm:. It can be uaed either u a ponablc er a permanont lixtun,, • Manual er Auto Start facilities • Low battery e cut-out. Kit version K 6770 $425.00 Fully built and tested 12V Input K 6774 $525.00 24V Input K 6775 $525.00 -0enz 0 $9.95 K2sss ::c a l] K 3301 $29.50 Auxlllary + AND - 12V Output Terminals a: l] ,, 10 Turn Output Voltage Control (K 3300 ii normally supplied with standard pot. ~ C m r r K33oo $195.00 TOP VALUE ~ OPTIONS :..J 0 z m 0 l] 1-9 (See Slllcon Chip Nov '87) a "'C :::c 100'5 OF USES AT HOME AND AWAY e Complete Kit K 6750 $279.00 Fully bullt and tested K 6755 $379.00 PHONEORDER TOLL FREE ALTRONICS 008 999 007 0 0 ....... PHONEORDER - TOLL -- FREE ALTRONICS 008 999 007 Multipurpose 120VA Mini pea r This transfonner is wound on expensive, grain oriented steel to make it super-efficient! And look at the size! Just 110mm x 65mm x 65mm High, weight l. 25kgs Primary: 240V Secondary: 12V - !OA, 15V - 8A, 24V - 5A, 27V - 4.4A, 30V - 4A Multipurpose 60VA Very Versatile ....... 0 0 this month only CX) $22.00 -----· with LARGE ferrite magnet from an incredibly low 99ccnts! C 0610 Normally $2.30 ea but look at this/ 1-9 only $1.25 ea 10 up 99 cents ea Save over 40% AVEA UNDLEAT LTR • - a: 0 z m 0 lJ C m Buy these by the ROLL and save an amazing 50% or --,........,. ~ ""C :::c lJ RE BARGAINS! 0 more! -~~ :? ~~;:,:.:;~o;~iiif 1 .J.1 LL£ 100% Screened Computer Cable et w w a: u.. W 0705 4 wire W 0710 6 wire W 0715 9 wire usually $1.40/M NOW $79.00per l00M usually $1.80/M NOW $90.00per l00M usually $2.30/M NOW $125.00per l00M ./r ••.•,%-,•w•,,.,.,,_,.,~--~- ·-- ~ Ml -· ·1 ..J ..J ~ ~ !~"!~~~~tM !!'"1"gain ! W ~ ,.,..?.',:· M 2165 Normally $26.50 each SAVE en $4.50 0 z EACH ~ AVE UP TO .95 EACH 10 up $25.00each. '0 I , 1\ Mini 57mm (2.25") 200 mW 8 Ohm This month 1-9 $30.00ea Output - Two tapped secondarles give: 240V to 3,6,9,12,15,18,21&24Volts at 60VA (60W) Use of high grade silicon steel has enabled surprisingly compact dimensions of 70mm x 70mm x 58mm high. a, a, a, 0 0 M 2175 Normally $39.95, Price Sen~ · usually 60ccnts/M NOW $70.00per 200M usually 80ccnts/M NOW $90.00per 200M usually $2.40ccnts/M NOW $295.00per 200M Redford Stereo Boggins of uses! Reduced to clear at $7.00ea or $6.00 each 5 or more. 60 Watt z 0 Calling all PA Techs! . . . _ '-/ .· , Telephone :I: Line " · _. a. Isolation Units - · All Telecom Approved Type 1 • Dc■ igncd to inl,:rfac:e paging output of PABX or Commander phone 1ystem11 to Public Addres1 Amplifier. C011I1cct1 to Aux. input A 0610 $99.00 w ONLY $99 Type 2 • Ptovidea "Music On Hold" (MOH) ., your C.ornrnandcr phone system. Progrmn input can be, radio, tape deck, landlinc etc. Max. output &OOmV P-P. A 0615 $99.00 Type 3 • Similar to type 2 (A 0615) except mu. output ii 2.8V P-P/ each A 0620 $99.00 . r _ ·-- - -- ' STROBE SIGNAL LAMPS Uses Xenon Strobe tube for High Ene'9y strobe flash at output rate of approx. 1 per second. Amazing light energy output for the small amount of_,usedDC input 12V 320mA. Dimensions: 97mm Diam.• 90mm Hl&h Save $5.00 each this month! S 5455 Blue S 5450 Red Normally $27.50 this month $22.S0ea Patio Loudspeaker Volume Control 0 ~ CD CD CD 0 0 ...... A2300 9.9 No more duhing fran the patio to the lounge and back to "Tum it down!'" or "Tum it up a bit!" Put this control on your patio and enjoy your party with your gueata. Massive 100 Watt music power capacity. Five volume settings and "OFF". Includes P 8045 mounting block. PHONEORDER TOLL FREE ALTRONICS 008 999 007 PHONEORDER TOLL FREE ALTRONICS-- 00-8 999 - 007 GUARD YOUR HOME! NEW! NEW! NEW! MULTI SECTOR BURGLAR ALARM HOUSE GUARD ALARM SYSTEM (Sec EA Man:!VApril'89) Bmglaricl aJ1: cm the inacaa::,! Doesn't it make acme to protcc:t your bom:: and its coo.tents? Tuia euy-to-build kit .-mbl.. cn a oinglc PC and INU.UDES 12V l.2AH inbuilt lead calcium back-up battery. Features include:• Emry and exit delay• PanK alarm input SIIIUlll BIUiaH~ peopk • prolcd • Battery back-up• Line monitoring• Soft alarm Lamp tell talc <>1tput ,011r prw11U.f•• •ltd e9uip,,,clll! • Auxillia,y relay for extcmal siren etc. • Key switch opcratim • u... almost KIT WITHOUT SIREN any tyl>C or IICtl50I'. start• "Schreecher Siren" 110db SPL s 5170 17.95 l'- 0 0 K 1910 89.00 Protect your Home or Bualnea from Intruders with this "State at the Art" Burglar Alarm System Over the last few years, House Break-Ins have increased dramatically. The recovery rate of stolen goods is very low. Now more than ever before, it makes extremely good sense to build and install this ingenious Multi-Sector System. This unique Alarm System incorporates the features of the more expensive commercial models - at a fraction of the price. Features:(See EA Jan/Feb'8S or our 1989 Cataloaue for full features) Back Up Battery 12V 1.2AHS5065 Kit (Less Battery Back Passive Infra-Red Up) Lite Guard ········· K 1900 $149.50 $29.95 ""C J: 0) 0) 0) 0 z m 0 High Energy Siren with ex, t 0 0 m en -z :IJ CJ 0 a: ~ c:( w w a: L1. ...J ...J ~ a: w C a: 0 w z 0 :c a. :IJ C How often have you thought there could be a prowler outside your door? Install a Lile Guard & (once armed) any "guest" will be floodl~ when detected by this highly sensitive Infra-Red Detector. Sp•dllcaUons: • Rain tight, <>1tdoor, all weather operatim • Operation Time: Adjustable 1-20 mim • S•nsltlvlty: Adjustable W - SO, 30 beams• Almable to dcsued duectim with 2 ball joints e Switching Capability: SOOW max. incandescent • Operation Modes: OFF, AUTO, TEST, MANUAL.ON. s 5350 was $135.00 SPECIAL ONLY $99.00 SAVE $36.00 Movement Detector Pulse Count Type Our 1989 model !RD now includes pulse count circuitry with a specific time delay between pulse scnsing. Three pulses of IR radiation arc rcquizcd to trigger the dctcctcr. Features: Lens - w idc angle & narrow angle l 12V DC Powered. S 5301 Absolutely ear splitting SPL 120db. Handy B,acket for wall mounting etc. 12V 300mA s5111 $24.5Q 79 (3) for $180 a rr- .,, :IJ m m e BANKCARD e VISA e MASTERCARD e PHONE TOLL FREE 008 999 007 )> Country clients please allow an additional 48-72 hours :IJ e NEXT DAY JETSERVICE DELIVERY 4LTilOnlC) Manufacturers. Contractors and Bulk Users Please Contact Our Wholesale Sales Dept. Sydney (NSW Only) ..Colin Fobister (02) 437 4077 Melbc.ume (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 & ANer Hour• (09) 328 1599 ALL MAIL ORDERS P.O. Box 8350 Perth Mail Exchange W.A.6000 STANDARD DELIVERY I PACKING CHARGE $4.00 to 1Kg $7 over 1Kg AUSTRALIA WIDE - We process your order the day received and despatch via . Australia Post. Allow approx 7 days from day you post order to whe n ycu receive goods $7.00 OVERNIGHT JETSER•ICE - We process your order the day received and despatch via . Ovwnlght JetMrvlc• Cour1er for delivery ne xt day Country areas please AL TRONICS RESELLERS allow additional 24-48 hours . Weight limit 3Kgs (3Kgs covers 95% of Orders) Chances are there 1s an Altronics Reseller rtght near you- check this 11st or phone us for $10.00 HEAVY HEAVY SERVICE - All orders ol t0Kgs or more must travel Express details of the nearest dealer . PIHH Note: Resellers have to pay the cost of freight and Road - Please allow 7 days fo r delivery insurance and therefore the pnces charged by 1ndrv1dual Dealers may vary slightly INSURANCE - As with virtua lly every other Australian supplier. we send goods at from .t his Catalogue • 1n many cases, however . Oea~er prices will sttll represent a consignees risk . Should you require comprehensive insurance cover against loss_or sign1f1cant cost saving from prices charged by Altrcn1cs Competitors . damage please add 1% to order value (minimum charge $1 ) . When phone ordering Don't forget our E1pre11 Mall and Phone Order Service - tor the cot1t of a local call, please request " Insurance" Bankcard. Vloa or Mutercard llolder1 can phone order tor oame day de1Datcll. TOLL FREE PHONE ORDER - Bankcard .Visa . Mastercard Holders can phone order Blue Ribbon Dealer• are highlighted with a ■ These Dealers generally carry a toll free up to 6pm Eastern Standard Time . Remember w ith our 0Yemtght JetNl'Ylce we comprehensive range of Allronic products & kits or will order any required item for you . deliver next day. WA COUNTRY ALBANY BP Electronics ■ 412681 ESPERANCE Esperance Communications 713344 GERALDTON K.B.Electronics & Marine 212176 KALGOORLIE Todays Electronics ■ 212777 KARRATHA Daves Oscitronic 854836 MANDURAH Lance Rock Retravision 351246PORT HEADLAND Ivan Tomek Electronics 732531 WYALKATCHEM D & J Pease 811132 NT ALICE SPRINGS Ascom Electronics 521713 Farmer Electronics 522967 ACT CANBERRA Bennett Commercial Electronics 805359 Scientronics 548334 VICTORIA CITY All Electron:c Components 6623506 SOUTH MELBOURNE Winscott Trading 6995740 SUBURBAN CHELTENHAM Talking Electronics 5842386 CROYDEN Truscott Electronics ■ 7233860 PRESTON Preston Electronics 4840191 COUNTRY BENDIGO KC Johnson ■ 411411 MORWELL Morwell Electronics 346133 QUEENSLAND CITY Delsound P/L 8396155 SUBURBAN CAPALABA David Hall Electronics 3902399 FORTITUDE VALLEY Economic Electronics 2523762 WOODRIDGE David Hall Elec tro nics 8082777 COUNTRY CAIRNS Electronic World ■ 518555 BUNDABERG Bob Elkins Electronics 721785 GLADSTONE Supertronics 724321 MACKAY Philtronics ■ 578855 ROCKHAMPTONAccess Electronics (East St.) 221058Xanthos Electronics 278952 TOOWOOMBA Hunts Electronics ■ 329677 TOWNSVILLE Solex ■ 722015 SA CITY Force Electronic ■ 2125505 SUBURBAN BRIGHTON Force Electronics ■ 3770512 CHRISTIE& BEACH Force Electronics ■ 3823366 ENFIELD Force Electronics ■ 3496340 FINDON Force Electronics ■ 3471188 LONSDALE Force Electronics ■ 3260901 COUNTRY MT.GAMBIER South East Electronics 250034 WHYALLA Eyre Electronics ■ 454764 TAS ANIA HOBART Geo rge Harvey ■ ~42233 LAUNCESTON George Harvey ■ 316533 Nichols Radio TV 316171 NSW CITY David Reid Electronics ■ 2671385 CARINGHAH Hicom Unitronics 5247878 COUNTRY COFFS HARBOUR Gotts Habour Electronics 525684GOSFORD Tomorrows Electronics 247246 GRAFTON East Coast Electronic 431250 NELSON BAY Nelson Bay Electronics 813685 NEWCASTLE Novocastrian Elect .S upplies ■ 621358 NOWRA Ewing Electronics ■ 218412 RAYMOND TERRACE Alback Electronics 873419 WINDSOR M & E Electronics 775935 WOLLONGONG Newtek Electronics ■ 271620 Vimcom Electronics 284400 PHONEORDER TOLL FREE ALTRONICS 008 999 007 ~ 0 -0z en 0 0 (X) <D <D <D 0 0 ~ BUILD THIS LOW-CAPACITANCE SCOPE PROBE By HERB FRIEDMAN What's that - your budget won't extend to a low-capacitance x10 scope probe? You can build this one using junk-box parts. Even if you're measuring well down into the bass audio frequencies, an oscilloscope's display of a complex waveform - such as a square wave - will not be accurate unless the input to the scope is made through a low-capacitance test probe. In the June 1989 issue of SILICON CHIP, we published an in-depth discussion on the why's and wherefore's of low-capacitance oscilloscope probes so there's no sense in repeating what's already been said. Suffice to say that, as a general rule, all AC scope measurements should be made using a low-capacitance xl0 test probe. Also, as a general rule, you're probably best off with a low-C xlO scope probe that's specifically designed for your scope. But what if you can't afford to buy one? Simple! You build it using readily available, budget-priced parts. From input to output, the prototype low-C xlO probe shown here can cost as little as $10. And by building your own, you get the extra advantage of precisely matching your scope's vertical input connector: anything from a modern BNC connector to a somewhat older banana plug, to an ancient microphone-type plug connector. Whatever your scope needs, just hang it on the end of the probe's cable. The circuit of a low-capacitance c, PROBE ,:. [!J . ..... T ~ PLUG COAX CABLE =----e 1 CLIP~ LOW CAPACITANCE PROBE FIG.I: ALTHOUGH A LOW-CAPACITANCE probe is a simple device, it plays a vital role in obtaining accurate oscilloscope traces. 76 SILICON CHIP FIG.2: A PLASTIC HANDLE, a metal shield, a probe tip and a small piece of perforated board are required to make the scope probe. Matching holes in the handle and metal shield provide access to Cl. FIG.3: THE RESISTOR SHOULD be placed to the side of CL Do not run the resistor across the top of the capacitor. FIG.4: THE POINTER INDICATES where the wiring board's solder lug is tack-soldered to the inside of the· shield tube. probe, shown in Fig.1 , is certainly simple enough because it essentially consists of three components: Rl, Cl and PL1. Rl can be any kind of ¼ W or ½ W resistor with a value of about 9 megohms. The actual value isn't all that critical; it can be 9.2Mfl or 8.8Mfl if you happen to have one of these values in your parts box. Trimmer capacitor Cl can be anything that physically fits inside the handle. The unit specified in the parts list is cheap and readily available. As already mentioned, PLl is whatever connector is need- ed to match your scope's vertical input. The problem is, however, to assemble Rl and Cl in a shielded probe - one that does not pick up extraneous hum and noise because of capacitance-coupling to the user's hand. On the other hand, even though the probe is shielded, it should be insulated from the user's hand to ensure safety. So you will need some form of plastic handle, a probe tip for the handle, an internal shield, a perforated wiring board, and a solder lug that can be connected as a common ground. Be sure to use perforated wiring board (the stuff without the copper strips). Don't use Veroboard or stripboard as the copper strips have too much stray capacitance. Just where you scrounge all the parts is up to you. The internal shield, for example, could be easily make up from a discarded tin can and should be about 10mm in diameter and about 80mm long. The PARTS LIST 1 9Mfl resistor, see text 1 trimmer capacitor (Jaycar Cat. RV-5706 or RV-5708 , DSE Cat. R-2930) 1 plug connector to match scope input, see text 1 piece of pert board 1 metal shield, see text 1 plastic handle 1 small alligator clip 1 solder lug 1 probe tip assembly, see text 1 2-metre length of coaxial cable, RG-58A/U or RG-58C/U FIG.5: YOU MUST CUT A NOTCH in the plastic handle s6 that the ground test lead from the shield tube can exit from the front of the probe. FIG:6: THE BNC CONNECTOR at the top provides shielding all the way into the scope. On the other hand, a banana plug causes a break in the shield which exposes the inner conductor to possible hum and noise pickup. perforated wiring board should be trimmed so that it slides neatly inside the shield. Construction Holes must be drilled in both the handle and the shield to allow access to trimmer Cl. Take extreme FIG.7: A FULLY SHIELDED CABLE will provide the rock-steady square wave display shown in (a). A break in the display, such as caused by a banana plug, can cause the trace smearing shown in (b).Closer examination of the smear in (c) shows a 60Hz (USA) mains noise signal superimposed on the desired signal. AUGUST 1989 77 FIG.8: THE PARTS FOR THE CRO probe could be fitted into this commercial probe case which is available from Jaycar for $12.95. Alternatively, a suitable case could be fashioned from a short piece of plastic conduit. FIG.9: THE TWO HALVES OF the Jaycar probe case simply clip together. There's more than enough room to accommodate all the parts. care when drilling the holes in the handle and the shield because they are prone to snag on the drill bit. You must create some kind of safe drilling jig when working with the handle and the shield. Fig.2 shows the probe-assembly components after the handle and the shield are drilled. A 6mm hole should be drilled in the metal shield about 8mm from one end and a matching hole drilled about 18mm from the front of the plastic handle. Fig.3 shows how the ground lug is bolted to one end of the board. Bend this lug upwards through 90° so that the board can slide through the metal shield. Position the lug so that it is inside the tube and exactly flush with one end. Mark the opposite end of the board at the end of the metal tube and cut the board exactly on the line. Install Cl on the board so that it is centred 8mm from the cut edge. You will have to enlarge the ex78 SILICON CHIP isting board holes so that the trimmer's lugs just barely squeeze through. Using Fig.3 as a guide, install a PC pin on each side of Cl; then install Rl between the pins so that it lies alongside Cl. Do not position Rl across the top of Cl. Notice from Fig.3 that' one of Rl 's leads at the front PC pin is left at fu]l length. This extra length will pass into the probe's tip during final assembly. Connect Cl to the two PC pins on the bottom of the board using short, direct lengths of wire. The connecting cable is 1-2 metres of conventional coax. To prevent constant flexing from snapping the centre conductor, use one of the cable types having a stranded centre conductor, such as RG-58A/U or RG-58C/U. Avoid RG-59 cable because its centre conductor is solid. The probe's ground is the solder lug on the wiring board. Unbraid the cable's shield, twist the strands tightly into a pigtail and solder the pigtail to the lug. This done, connect the cable's centre conductor to the nearest PC pin that supports Rl. Finally, slip the shield tube over the board until the back end is exactly flush with the solder lug. Force or bend the lug against the inside of the shield, then rotate the shield so that it's hole is exactly opposite Cl and tack solder the lug to the inside of the shield. Fig.4 shows the details. Using a knife or a 3mm drill bit as a router, cut a slot for the grounding test lead in the front of the plastic handle, 180° opposite to the 6mm hole. This done, solder a 15cm length of stranded insulated wire to the front of the metal shield. Once again, this should be diagonally opposite to the adjustment hole. Now slide the assembly into the handle so that the holes for Cl are in alignment and the ground test wire flows out the slot. Terminate the ground lead with a small alligator clip. The next step is to assemble the probe tip. It's up to the constructor to devise a suitable probe assembly. For example, you could use parts from a discarded multimeter test probe. The probe tip assembly should be mounted on a plastic end piece and the resistor lead soldered directly to the probe tip. This end piece can be secured to the handle using small retaining screws. Alternatively, you could house the entire project in a ready-made probe case which is currently available from Jaycar (Cat. HB6400; $12.95). FIG.to: ADJUST Cl USING an insulated tool for optimum squarewave scope display. banana jacks for the vertical input connections then PLl must be a banana plug. Adjustment (b) (a) FIG.11: IMPROPER ADJUSTMENT of Cl will produce the rounded leading edge shown in (a) or overshoot of the leading edge as shown in (b). Ideally, PLl should be a BNC connector but some scopes may require the use of a banana plug connector. Bear in mind that, as shown in Fig.6, a BNC connector provides full shielding all the way from the probe to the scope's input, while a banana plug actually breaks the shield at the connector and will allow some noise pickup. For example, on a square wave signal, a BNC connector gave a rock-steady trace as shown in Fig.7a. In Fig.7b, PLl was a banana Garbage Reminder ctd from page 52 To set the unit, all you need to do is insert the batteries at the time you want the LED to begin flashing on your garbage collection day or days. The LED will flash for 7 hours and 12 minutes unless stopped using the BIN OUT switch. Normally the reminder would be set to start the LED flashing at about 5pm or 6pm. It does not matter which day the batteries are inserted since the days are selected using the DIP switches. Day 1 is the day that the Reminder is set, day 2 the next day and so on. For example, if the Reminder has its batteries inserted on Wednesday at 5pm, day 1 is Wednesday and day 7 is Tuesday. If your garbage night is Sunday and Wednesday, the required settings are switches 1 and 5 on. All other switches are off. Got it? Good. Now get that garbage out! ~ plug that was connected to a BNCbanana adaptor. Notice that noise (hum) pickup has caused the trace to "smear" . Fig.7c is the same trace as Fig.7b but a faster camera shutter was used to show that the "smear" is actually another signal (60Hz mains signal leaking through the broken shield at the banana plug) that is superimposed on the square wave. So if possible, maintain shielding throughout the entire assembly. Of course, if your scope only has To adjust the probe, set the scope's vertical input for DC. Then, using any known good square wave as the signal source - lkHz is almost a universal standard - use an insulated alignment tool to adjust Cl for the precise square wave shown in Fig.7a. Improper adjustment of Cl will result in a rounding of the signal's leading edge (Fig. 11 a) or overshoot of the signal's leading edge (Fig.llb). Refer to the scope probe article in the June issue to learn why Cl 's adjustment does what it does. Finally, be sure to allow for the x 10 factor when using the low-C xlO probe. For example, if the scope indicates that a signal is 1.1 volts p-p, then the actual value is 11 volts p-p. ~ Copyright 1989, Gernsback Publications. Reprinted with permission from January 1989 Radio-Electronics. MAKE YOUR DREAMS COME TRUE LAPTOPS FROM s1995.oo *INTERNAL BATTERY, EXTERNAL AC ADAPTOR * LIGHT, FAST, 10MHz * COMPACT AND CONVENIENT * SUPER TWIST LCD DISPLAY *640KB RAM *SERIAL AND PARALLEL PORT * REAL TIME CLOCK LASER PRINTER s2995.oo * 6 PAGES PER MINUTE *SERIAL AND PARALLEL (DUAL HOST) * 6 BUil T-IN FONTS * HP LASER JET SERIES II EMULATION * OPTIONAL IBM PROPRINTER EMULATION * 4 ADDITIONAL SOFT FONTS INCLUDED * EXPANDABLE TO 4.5MB COMPUTER CARE KIT s115.oo * 6 CLEANING KITS IN ONE *SUITABLE FOR ALL COMPUTERS --- ,__; Jib a ¾ ·k, .,... -- ALL PRICES INCLUDE SALES TAX FREE ALL PURPOSE CLEANING KIT WITH HARDWARE PURCHASES FREEPOST NO. 31 ESCKAY PRINTERNET PO BOX 2591, NTH PARRAMATTA, 2151 TEL: (02) 891 1282 AUGUST 1989 79 IBM PC/XT/AT COMPATIBLE KITS ~ !Hllll\Hlliil! KIT 1 10MHz Turbo with 1MB RAM and virtual disk software included. XT 10M Hz Motherboard $149 XT Case Flip Top $ 99 XT Power Supply 150W $125 AT Style Keyboard $109 1MB RAM $445 Floppy Controller $ 99 Floppy 360k 5 1/4" $179 MGA Card $109 MGA Monitor $199 TOTAL $1533 KIT PRICE $1295 SAVE $238 Assemble a computer to your own specifications using only a screwdriver and pliers. Disk Drive Options - pricing is va lid only if purchased with CPU kit 20MB Hard Disk including controller $499 40MB Hard Disk including controller $699 KIT 2 12MHz AT Turbo Kit AT Motherboard AT Case Flip Top 200W Power Supply Keyboard 2MB RAM Floppy Controller 1.2MB Floppy Disk Drive MGA Card MGA Monitor TOTAL KIT PRICE $2199 SAVE $263 Video Options - pricing is only valid if purchased with CPU kit. CGA instead of MGA includes Philips CGA monitor $349 EGA instead of MGA includes EGA monitor $699 $499 $129 $199 $109 $890 $ 99 $229 $109 $199 $2462 I Upgrade to 16MHz NEAT with EMS 4.0 software for only $275 .___ _ _ _ _ _ _ _ ___. MOTHERBOARDS IBM PC/XT COMPATIBLE TURBO 10MHZ MOTHERBOARD CONTROLLER CARDS 360KBfl20KB/1.2MB/1.44MB FLOPPY DISK DRIVE CONTROLLER CARD FOR IBM PC/XT/AT AND COMPATIBLE COMPUTERS -Allows connection of one or two 360KB, 720KB, 1.2MB or 1.33MB floppy disk drives. Includes cable for two internal disk drives and manual. $99 -Expandable to 640K RAM using 4164, 41256 & 41464 120ns chips -4.77 or 1OMHZ hardware or keyboard selectable operation -Front panel LED indicators supported -Eight expansion bus slots -AMI BOIS ROMs included -8087-1 Math co-processor capability -Performs at an average speed of 100% faster than the original IBM PC/ XT -Nortgn SI rating of 2.0 -Size (12" x 85") -Weight (175Ibs) $1 49 FLOPPY DISK CONTROLLER CARD FOR IBM PC/XT AND COMPATIBLE 'S -Run up to four 360KB disk drives -Includes cable for two internal drives -DC37S connector allows for an additional two external drives (external cable not included) -complete with manual $55 MFM H/D DISK CONTROLLER CARDS FOR IBM PC/XT/AT & COMPATIBLE'S -8 bit MFM hard disk controller card for the 1MB PC/XT and compatible computers. Can be used with many types of hard. disk drives. Cables and documentation included. $139 H/D DISK/FLOPPY CONTROLLER FOR IBM PC/XT AND COMPATIBLE'S - 8 bit floppy and MFM hard disk controller for the IBM PC/XT and compatible computers. It will allow connection of up to two hard disks and two floppy 360, 720KB, 1.2 & 1.44MB drives. Cables are included to allow connection of one hard disk and two floppy disk drives. To connect a second hard disk drive an additional cable will be required. $175 HARD DISK/FLOPPY CONTROLLER FOR IBM AT AND COMPATIBLE'S IBM AT COMPATIBLE 12MHZ 80286 MOTHERBOARD - 16 bit floppy and MFM hard disk controller for the IBM AT and compatible computers. It will allow connection of up to two hard disk drives and any combination of two floppy disk drives. To connect a second hard disk drive an additional cable 'hill be required. $245 lvlFM HARD DISK CONTROLLER CARD FOR IBM AT AND COMPATIBLE'S - 16 bit MFM hard disk controller for the IBM AT and compatible computers. It can be used with many hard disk drives. Cables are included. $220 IBM PC/XT/AT COMPATIBLE KEYBOARD CASES -101 Key -Enhanced keyboard layout -Tactile touch keyswitches -12 Function keys -lluminated LED indicators for Num Lock, Caps Lock and Scroll Lock -Seperate cursor pad -Low profile design -Automatically switches between PC/XT or AT -Manual included -Colour beige -Size l19"w x 8"d x 1.33"h) -Weight (4.6Ibs) $109 84 KEY KEYBOARD WITH TRACKBALL $99 $195 2MB MEMORY EXPANSION CARD FOR IBM AT AND COMPATIBLE COMPUTERS -Utilizers (72) 41256-120ns chips for the full memory capacity of 2Mbytes -Offers conventional expanded and extended memory capabilities -Features auto-parity check -EMS compatible driver -RAM disk and print spooler software included $245 MEMORY CARD PC/XT for 640K $99 -Manual included 8088 $99 BABY 8088 $129 BABY 80286 $129 MINI TOWER $199 MAXI TOWER $699 with power supply JAPANESE DRIVES 3.5" 1.44M/720K Switchable between 1 44/720 DS/DD 3.5" Mounting $225 5.25" mounting $2119 5.25" 360K Drive 500K unformatted XT compatible $179 5.25' 720K/1.2MB Drive To 1.6MB unformatted AT compatible $229 5.25" 40MB Hard Drive 50MB unformatted. 28ms average seek time $599 MONITORS 12" TTL Green $179 12" TTL Amber $179 CGA 14" TTL Colour Philips 2 year guarantee. Stereo sound suits PC and Amiga $525 EGA 14" TTL Colour $6119 1/0 CARDS RS232 HALF CARD FOR IBM PC/XT AND COMPATIBLE COMPUTER -Fits the difficult to use half card slot or any long slot -RS232 card comes with one ready to go serial port -Expandable to 2 ports by user (parts for expansion not included) -Selectable for COM1 thru COM4 -The user is able to select addresses for ports A and B as well as interrupt requests -Manual included PHONE (02) 418 6711 FAX (02) 418 6713 VISA Mail Order Address: P.O. Box 1100 Lane Cove NSW 2066 NEAT MOTHERBOARD $795 -Norton SI rating of 15.6 $55 1/0 CARD FOR PC/XT W/GMS CLCK $125 1/0 CARD 2 PORT FOR AT $65 1/0 CARD FOR AT WITH GAMES $125 MULTI 1/0 CARD WITH MONO GA $229 MULTI 1/0 CARD $149 PERSONAL COMPUTER MARKETPLACE Pty Ltd -Expandable to 1MB RAM using 256K DRAM chips -Expandable to 4MB RAM using 1MB DRAM chips -Expandable to 2.5MB RAM using a combination of 256K and 1MB DRAM chips -8 or 12MHZ hardware or keyboard selectable operation -Front panel LED indicators supported -Six 16-bit and two 8-bit expansion bus slots -AMI BIDS ROMs included -Zero wait state -Selectable RAM chips speed (80 or 100 nanosecond) -80287-8 Math co-processor capability -Norton SI rating of 13.7 -Size (13" c 8.75") -Weight 12 25Ibs) $499 FREIGHT CHARGES Include S10 with order for all normal items - heavy items, e.g. monitors add S15. IBM AT COMPATIB LE 200W POWER SUPPLY -Input <at>47 -400Hz l110/240V switchable) -Output +5v<at> 20A, -5V<at> 0 5A, +12v<at> SA, -1'2:v<at> 0.5A -Plug compatible connectors -Built in fan Size 16 5"1 x 5.88"w x 6"h) P/S 150W P/S 150W BABY $199 $125 $145 COMPUTER BITS By JENNIFER BONNITCHA Display adapters - from monochrome to thunderdome Early personal computers used to blank the screen while they were performing operations but modern computers don't because they have separate circuitry including dedicated memory to drive the video monitor. This is why we have monochrome display adaptors, colour graphics adaptors and so on. The smallest IBM PC ever made had 16K of RAM. The operating system fitted into working storage but there wasn't much left for anything else. You could write simple BASIC programs but sophisticated applications such as spreadsheets, word processing, graphics and accounting simply would not fit in such a small memory area along with the operating system. During the reign of the 8-bit Apple, Tandy and Commodore computers, 64K of memory seemed ample to run many software products, A Monochrome Display adapter (MDA) drives a monochrome display in text mode using special character generator circuitry contained in the card. 82 SILICON CHIP and run them well. The announcement of IBM's 16-bit personal computer in 1981 changed all that. The IBM PC heralded a new age in both computing and the amount of memory required to run a program. As the applications became more complex, the memory requirements increased, although not at a proportional rate. Increased memory was primarily required for programs utilising colour and producing graphics (and not to mention lazy programmers writing volumes of program code). The need to produce better images brought about a rash of third party add-ons ranging from memory boards through to monitors and graphics boards. Although many types of display adapters can be used on the PC, two adapters represent a large majority of those already in use - the IBM monochrome display and printer adapter card and the colour/graphics monitor adapter. Demand by users has seen the enhanced graphics adapter become the defacto standard for screen display. The monochrome monitor supplied with the original IBM PC was a high-resolution, long-persistence green phosphor display. Longpersistence phosphors tend to prevent any flickering of the image on the screen however they also tend to prevent use of a light pen. The screen was a nominal 30cm diagonally, capable of displaying 25 lines of 80 characters using a 9 x 14 dot matrix to form the characters. An Enhanced Graphics Adapter (EGA) card supports the monochrome display, the colour display and the enhanced colour display. It can support 640 x 350 pixel resolution and display up to 64 colours. Although the position of the characters on the screen changes, their size and shape are fixed. To use the monochrome display, a Monochrome Adapter had to be installed into one of the system expansion slots. The adapter has a 9-pin video connector to which the cable from the monochrome display is attached. A second 25-pin connector. enables the connection of a printer with parallel interface to the system unit. Using connections from the monitor to the electrical outlet at the rear of the system reduces the requirements for power points to power the entire computer system and simplifies the power on/off procedure - just switch the computer on and the monitor is on too. Monochrome Display Adapter The Monochrome Display Adapter (MDA for short) drives the monochrome display in text mode using special character generator circuitry contained in the card. It contains 4000 (4K) 8-bit bytes of onboard display memory. Since the computer uses the card's memory to display screen information, the computer's Random Access Memory (RAM - the computer's thinking and working space) remains unaffected by the display of information. · Although the card allows a limited capability for drawing line and block characters, such as when Borland Sidekick is used, no true graphics capability is present. So if you want to see your work in living, breathing colour, you need the Colour Graphics Adapter (CGA). Colour Graphics Adapter The CGA card has several video interfaces as well as a light pen connector for those who cannot live without one. You can have either a 9-pin "D'' type shell RGB (Red, Green, Blue) connector for a TTL colour monitor or a composite video output via an RCA phono socket to feed a monochrome monitor. Behind the retaining bracket sits a 4-pin Berg strip for connection to an RF modulator. The modulator could then, in turn, be connected to the trusty TV however the lower resolution and bandwidth of the TV normally limits the display to 40 characters per line rather than 80 characters. These days though, few serious users would be using an IBM computer or compatible with video display via a normal TV. The CGA card permits black-andwhite (monochrome) or colour operation via a TTL colour monitor. The two basic modes of operation of the card are text (alphanumeric) and graphics (All Points Addressable - APA). Within each mode, several display character widths or pixel sizes are available for selection. Text mode differs somewhat from that of the monochrome adapter. It also contains circuitry to produce text characters on the screen, this time in colour or black and white. As already noted, you can operate the monitor in 40-character by 25-line mode if you have a low resolution monitor or TV. With a high resolution monitor, the PC can operate in an BO-character by 25-line mode. Text mode enables character blinking, highlighting and reverse video under program control. The actual characters are formed within an 8 x 8 dot box where each character is 5 x 7 dots with a 1-dot descender (lower part of letters such as "g"). The letters in this mode are different in shape and fineness from those produced by the monochrome adapter; generally the letter quality of the monochrome adapter is far superior. In total, 16 foreground and 8 background colours for each character, together with individual character blinking under program control, are suppqrted by the adapter. The CGA card contains 16,384 bytes (16K) of RAM storage. A 40-character by 25-line screen display uses 1K to store character information, while an additional 1K contains the attribute/colour information required by the screen. Since 2K of memory is required to display a 40 x 25 screen, up to eight pages or screens can be stored in the card's memory. The PC's processor allows direct addressability of the colour/ graphics card thus permitting a large degree of software flexibility for managing data on the screen AUGUST 1989 83 The Video Graphics Array (VGA) provides an analog RGB output to the monitor and can support 256 simultaneous colours from a choice of 262,144. It offers BIDS level compatibility with MDA, CGA & EGA. or a large degree of anguish for some early "clone-makers" . In graphics mode, three resolutions are available - low resolution 160 x 100 pixels (picture elements), 320 x 200 pixels (medium resolution) and 640 x 200 pixels (high resolution). The lowest resolution 160 x 100 pixels is seldom used; the medium resolution 320 x 200 mode enables each pixel to use one of four colours. One of 16 background colours may be selected and then three other colours from one of two palettes (cyan, magenta and white or green, red and brown). However the medium and high resolution modes differ in their utilisation of colour due to the fixed amount of memory available in the CGA card. In higher resolution 640 x 200 mode, the card requires all available memory to define the on or off state of each pixel and thus the display is in two colours only black and white. Differences in the way the signal is sent to the monitor and in the monitor resolution itself mean that not all colour monitors will have all colours available. Enhanced Graphics Adapter The Enhanced Graphics Adapter (EGA) card supports the monochrome display, the colour display and the enhanced colour display. In monochrome and enhanced colour display modes, the card supports 84 SILICON CHIP 640 x 350 pixel resolution with the capability to display up to 64 colours in enhanced colour display mode. Typically the EGA card may consist of several modules, depending on the manufacturer. In the case of IBM, the board consists of several modules: the extended graphics adapter (EGA) which is a full-slot board containing 64K of RAM; a graphics memory expansion card (GMEC) containing 64K of RAM which piggybacks onto the EGA; and finally a graphics memory module kit that adds an additional 128K of RAM to fill out the GMEC. The GMEC and memory module kit permit the display of 16 colours simultaneously in the enhanced resolution mode compared to four in basic EGA mode. Professional Graphics Adapter Squeezed in at this point is the Professional Graphics Adapter (PGA), a card producing analog RGB signals for the monitor which IBM released in order to allow for the display of a wider range of colours. Until this time, the MDA, CGA and EGA cards had been designed for connection only to TTL monitors. Therefore, to use a PGA card, you need a PGA monitor which will accept analog RGB signals. These are available, at a price, and are generally compatible with EGA cards too. With the release of the PS/2 range of computers, IBM introduced with them a new video display adapter, the Multi-Colour Graphics Array (MCGA - a variant of VGA) and Video Graphics Array (VGA). The immediate difference between these "standards" and their predecessors is that the graphics circuitry and associated video BIOS [Basic Input Output System) is actually present on the motherboard using custom gate array chips. In addition, new extended video modes and analog output enable support for up to 256 simultaneous colours from a choice of 262,144. The MCGA offers BIOS level compatibility with CGA monitors while VGA is jack-of-all-trades and offers BIOS level compatibility with the MDA, CGA and EGA. MCGA has four additional operating modes in addition to CGA compatibility; the first is a 320 x 200 pixel graphic mode with 256 colours from a palette of 256K colours. This is double scanned on the monitor to produce an image that is 320 dots wide by 400 high, with each of the 200 vertical dots appearing twice - one beneath the other. The second is the 640 x 480 pixel mode where the first and second graphics modes have a unity aspect ratio. This means that in the case of say a circle, the image appears circular and not elliptical as would be the case on CGA. MCGA's two text modes provide either 40 columns x 25 rows in 16 colours or 80 columns by 25 rows in 16 colours. The character size for both modes is 8 x 16 dots. VGA is basically a superset of EGA which supports many of the VGA-specific display modes such as 640 x 480 pixels in 16 colours when driven at higher frequencies. VGA also provides compatibility with the past while providing a glimpse of the future. Take a digital to analog converter chip to help drive the new analog monitors, some extra logic and a little work on the video ROM [Read Only Memory) BIOS and, hey presto, software aimed at the VGA could be adapted to suit the enhanced available EGA hardcontinued on page 99 Hew column on computer hardware SUBSCRIBE SUBSCRIBE SUBSCRIBE Have SILICON CHIP delivered direct to your door at no additional cost. Each month, we'll bring you the best and brightest electronics magazine, put together by Australia's most experienced team. • • • • • • :i J Police radar: it's not al~ ays right '} Intelligent charger for 12V gel batteries CONSTRUCTIONAL PROJECTS AMATEUR RADIO VINTAGE RADIO COMPUTER BITS THE WAY I SEE IT INFORMATIVE ELECTRONIC STORIES ~----------~-- - ------ ---------------FREEPOST* 24 Hour Fax Service (02) 982 9553 Send the coupon with your Credit Card details. 24 Hours, 7 Days a week. 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(PLEASE PRINT) Street_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ Suburb/town _ _ _ _ _ __ _ _ __ _ Postcode_ _ __ 1 year ( 12 issues) Australia □ $A42 2 years (24 issues) □ $A8 4 □ $A130 NZ & PNG (airmail) D $A65 Overseas surface mail □ Overseas airmail □ $A 1 20 □ $A130 $A62 0 $A2 4 0 Enclosed is my cheque/money order tor $ _ _ _ or please debit my □ □ Visa Card Bankcard Card No. I 1 1 111 i □ MasterCard 11111 111 1 1 Signature _ _ _ _ _ _ _ _ _ Card expiry date_ _ / __ / _ _ ~ ~ L- ------------------~---J AUGUST 1989 85 JAYCAR Nol FOR BARGAINS 5 for $1 IC SOCKETS 25% OFF SEMICONDUCTOR BARGAINS Si1e Cat Normal Price 8 14 Pl-6500 Pl-6501 ~ 2~ Pl-6502 ~ Pl-6503 32~ 20 Pl-6504 48~ 22 PI 6505 50 ~ 65 24 Pl - 06 ~ 55 7 7 28 Pl - o ~ 40 Pl-6508 7~ Standard production style sockets. PCS mount, solder tail, all tin plated Phosphor Bronze or Beryllium Copper. SAVE UP TO 9 6 ~ ~ 1 618 Type Cat Normal Price (ea) · · ' 74LS352 ZS-5352 $1.50 5 for $1 . ; 74LS109 ZS-5109 $1.25 5 for $1 ' '[ · 4528 ZC-4528 $1.95 5 for $1 . I 4538 ZC-4538 $2.65 5 for $1 4419 ZC-4419 $4.40 5 for $1 4076 ZC-4076 $1.20 5 for $1 ~ ~ 4028 ZC-4028 $1 .95 5 for $l 4024 ZC-4024 $1.18 5 for $l LM301 ZL-3301 $0.95 5 for $l Mll~IMUM PURCHASE $5 Ca:, be 5 different $1 units or any combination of $1 units adding up to $5. r 6810 RAM BARGAIN WAS $2.50 ea NO\\' $1 each Cat. ZZ-8056 COMPUTER CONNECTORS SAVE 50o/o - 112 PRICE - Sale Price 1-9 1~ 1~ 21~ 24t 10-99 13.~ 16~ 1~ 21~ ~ ~ 3~ 34~ 3~ 52~ 52~ 34~ 49\l 49\l MACIIINED AfflCRAFf GRADE ALUMINIUM FLASIILIGIIT What an excellent product. It measures 145mm long and runs off - 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 glove box 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 directly imported these and can offer them at the amazing price of only $9.95. Spare bulbs available for only $1 .50 (Cat. ST-3002) Cat. ST-3000 ONLY $9.95 MAGNI.,YING GLASS Magnify the savings you make by buying at Jaycar! Also good for checking small components as well. Every toolbox should have one. L~ns 35mm dia .. handle 40mm long. Cat. OM-3500 iD ies not 111l1gnify our 1' ices s.i her!) Turn Your Surplus Stock Into CashU Jaycar will purchase your surplus stocks of components and equipment CALL GARY JOHNSTON OR BRUCE ROUTLEY (02) 747 2022 lllJBBER J<'EE'I' BAllGAIN Centronics IDC LINE SOCKET Cat. PS-0896 ~ Cat Price $9.95 .~ _ LESS 50% $4.98 ~>::::S · , 10+ $4.50 ea . ~ Centronics IDC PLUG Cat. PP-0892 Cat Price $8.50 LESS 50% $4.25 10+ $4.00 ea 25D8 FEMALE 90% Cat. PS-0845 AUTOMATIC TELEPHONE DIVERTER 0 This device will divert an incoming 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 and telephone leads. Double adaptor Cat. YT-6020 $4.95 may be required. Cat. YT-6510 NORMALLY $249 SPECIAL $229 * Cat Price $6.95 LESS 50% $3.48 10+ $3.20 ea 15D8 FEMALE 90% ,.:.;-;;.;T-u"'i:rRA.soMC' Cat. PS-0826 !l :J.EANER Cat Price $3.50 l.ESS 50% $1. 75 10+ $1.50 ea Cat. HP-0828 SAVE $20 DIGITAL 400 MIP AC CLAMPl\lETER This is a direct import 0.5' LCD clamp meter with rugged hard vinyl carry case and an exceptionally low price - especially when you realise it has digital hold I The unit is overload protected. has a carrying lanyard and is moulded in a high impact dark grey plastic case. SEE 1989 catalogue page 37 for full specifications. Cat. QM-1570 CAT PRICE $139.95 NOW ONLY $119. SAV $2 ',, DIGITAL MUI,TIMETER "'ITU EVERYTHING This really Is the all singing, all dancing DMM. Jay car•s direct bnport saves you nt0ney again Just look at the featuress ■ ■ ■ Frequency counter Temp measurement Transistor tester ■ Capacitance tester ■ Diode tester ■ Continuity buzzer ■ Data hold ■ 20 amp current ■ 28 ranges Cat. QM-1 450 The Sensational 30 Piece Engineers~ Driver Set Here's what you get: 5slotted bits 0-1 , 3-4, 5-6, 8-10, 12 ■ 5 Hex bits 3/32' , 5/64' , 7/64', 1/8', 8/64' ■ 4 Phillips bits No. 0, 1, 2 & 3 ■ 4 Square Recess bits No. 0, 1, 2 & 3 ■ 6 Tone 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 it's all housed in a sealable tough plastic case. Cat. TD-2000 ■ $19.95 CAR NEGATIVE ION GENER ATOR .~ow you can have all the benefits of your home ioniser in your car. This great Jaycar direct import is durable, stylish and compact, measuring only 110mm in total length. It simply plugs directly into the lighter socket in your car, it can generate large amounts of negative ions for purifying the air, and some ozone for eliminating odour. Jaycar's direct importing cuts out the middleman and saves you money. ONLY $169 SPECIAL OFFER ONLY $34.95 Cat YX-2910 FM STEREO TRANSMITTER .. MINI MITTER" Ref: Silicon Chip October 1988 T~is fantastic project enables you to transmita signal IN s·,'EREO over the FM band. The range is limited to about 20 metres or so, so it's not a nuisance to anyone else. It uses a single 1.5V AA (penlight) cell which lasts for ages. Just imagine! You can listen to your CD player on your FM headphone receiver while washing your car! You can play your Walkman CD player over the car stereo - no wires! The possibilities are endless! Set up your own micro FM radio station! The Jaycar kit includes the hard-to-get Rohm BA1404 chip and the CORRECT 38kHz crystal even harder to get! All other parts included as well. Cat. KC-5041 ONLY $34.95 240 volt - SAVE $50 Cat. YX-2905 ONLY $29.95 00000 smEN MADNESS Another distress stock purchase whic h -ves you lots of nt0ney. This time two sirens. SCR EAIUER HORN We used to sell this unit years ago for $35. Today, it would cost about double that. Ideal for car alarms and home burglar alarms. It's very loud, the specs say 112d8, but we think it's louder than that. It has a nylon case and the noisemaker is a nylon 4' speaker. It's weatherproof and operates from 6-12 volts. Current drain 2 amps and the frequency is 1200-l SOOHz oscillating. Supplied with mounting bracket. Size: 110 x 100mm SPECIAL IC AND CRYSTAL FOR MINI MITTER rn AVAILABLE SEPARATELY 6A-1404 Trans IC Cat. ZL-3995 $6.75 38kHz Mini Crystal Cat. RQ-5299 $885 NEGATIVE ION GENERA.TOR GIVEAWAY PRICE· ONLY $25 ea Cat. LA-5262 ~~~~~~~ PERSONAL DATABA.NW CAl,CULATOR 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. It also has a spa;ial security code, so those private phone numbers can't be retrieved by anyone but you. Other features include: NORMALLy $39.95 ■ ~uto power off SAVE $ 5 ■ sd1t feature 1 ■ 0digitcalculator ■ Includes battery We have ser.n these for as 'lluch as $7H.95, but with our direct import we can offer them for· half that price Cat. QM-7200 ONLY $34.95 ** * * LARGE PIEZO SCUEAt,IER J\Jot unlike our tweety pie, this unit is larger (80 x 105mm) and is noused in a zinc die cast body. This is rare, as most these days are plastic. Sound level is 124d8. Operating vol tage 6-1 2 volts. current drain 3S0mA Ideal for car and home burglar alarms. Normally worth about $39. A bargain at $25. Cat. LA-5265 ONLY $25 *** 12 VOl,T ILI,UMINA.TED BEZELS Another surplus scoop purchase These bezels are identical to the expensive rectangular illuminated switches for car alarms, except that there is no switch. Quality European brand Arrow Hart. Normally worth $16 each. Complete with globe. Yellow Cat. SL-2670 rectangular Orange Cat. SL-2671 rectangular Green Cat. SL-2673 rectangular Yellow Cat. SL-2675 square Yell ow Cat. SL-2673 round ONLY $3.95 ea 10+ $3.50 •• LIGHTNING - STATIC ARRESTOR Every ham and CB operator needs one or two of these. PL259 connector with lug for earth. NORMALLY $3.95 ONLYZFOR$1 Cat. PP-0692 C ',r ...~. .,_ ~ ~ _...:v.,···i./ ?' , ~-:-(-?'. /:.. ,,,, I.11£?·:·; '. ,. '. ' ., -" Non School/Non Government Accounts Manufacturers! Open an account with Jaycar! Find out more by calling in to any Jaycar store or call (02) 747 2022 or send us a Fax (02) 744 0767 - or write I We will send you an acount application form by return. It's that simple! DIGITAi, 'l'IIEll~IOIUETER Forget the mercury type thermometers - this new digital mooel will measure body temps from 32-43°C. Simply push the button and place the thermometer in the mouth or under the arm. A beep tells you when it has stabilised. We have seen these for as much as $29.95 - Jaycar's direct import saves you money. Cat. QM-6300 $12.95 6 PIECE TEST LEAD SET FEATURES ■ Erase up to 9 chips at a time ■ Chip drawer has conductive foam pad ■ Mains powered ■ High UV intensity at chip surface ensures I ■ Engineered to prevent UV expos ■ Long UV tube life Cat. XE-4950 li . onsists of 2 leads with screw sockets one ach end and attachments screw in. 4 x alligator ips, 4 x 2mm pin tips, 4 x banana plugs, 2 x pade lugs. All colour coded red a $99.50 i' './ i1 '.) i, !, · A great way to never be out of that odd component & save a packet ('cuse the pun!) at the same time. 1/4\V Resistors 5% t_;_ ~- AB These beautifully crafted rack cab,ne ·&. ·,,~;;:a~~:11:t~fi I' ' · p) will give your equip bi' ,,, ' nm EASY WAY TO BUY OUR COMPONENTS a!".. • -·· . . . • Assorted colours and lengths of popular wire for wire wrapping. Cat Colour Pack WW-4312 Blue 100 WW-4314 Green 100 WW-4316 Red 100 Length 3.5 inches WW-4332 Blue 100 WW-4338 Red i ength 5.5 inches SAVE$3 ONLY $3.95 pkt , 1 construction. Removable top a m panels. :! Natural or black finish. All dimensions conform to International 1 standards. Ventilated lid. Deluxe brush finish anodised front panel. Side Elevation: D= 254mm; C• internal chassis height B mounting bolt centres. Cat Finish A B C Ea +5 HB-5411 Natural 44 34 38 $65 $62 HB-5413 Natural 88 57 82 $75 $71 HB-5415 Natural 132 89 $90 126 $85 HB-5410 Black 44 34 $65 38 $62 HB-5412 Black 88 57 82 $85 $80 HB-5414 Black 132 89 126 $95 $90 .?:- 7 different packs SAVE $22.55 a.,er buying individual parts. Each pack contains 10 of each value • TOTAL 120 RR-1690 -1, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8. 8.2 RR -1691 -10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82 RR-1692 · 100, 120, 150,180,220,270,330,390,470,560,680,820 RR-1693 -1k, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 82k RR-16!14-101c, 12.15, 18,22,27,33,39,47,56,68,821< RR-1 695. 100!<, 120, 150,180,220,270,330,390,470,560,680, 820k RR-1696 -1M. 1.2. 1.5, 1.8, 2.2, 2.7. 3.3, 3.9, 4.7, 5.6, 6.8, 8.2, 10M 11301 . & 1• Freezer Spray Cat. NA-1000 $6.95 ONLY $3.95 per pack Buy 1 pack of each (820 resistors) for only $19.95 - SAVE $7.70 Pot Lu.be C,1 RR-1697 $7.95 l} r= ' 1/ Cat. NA-1010 $6.95 ea Pack 1. 0.001, 0.0012, 0.0015, 0.0018, 0.0022 C,,t. RC-5000 P,i::k 2. 0.0027, 0.0033, 0.0039, 0.0047, 0.0056 C,,t. RC-5001 Pack 3. 0.0068, 0.0082. 0.01. 0.012, 0.015 Cat. RC-5002 Pock 4. 0.018, 0.022, 0.027, 0.033, 0.039 C~t. RC-5003 Pack 5. 0.047, 0.056, 0.068, 0.082, 0.1 Cat . RC-5004 $9.95 CERAMICS - 8 different paeks 10 of each value in each ack • total 60 units Pack 1. lpF, 1.2, 1.5, 1.8, 2.2, 2.7 Cat. RC-5390 P3r~ 2. 3.3pF, 3.9, 4.7, 5.6, 6.8, 8.2 Ca:. RC-5391 $6.95 Park 3. lOpF, 12, 15, 18,22,27 Ca,. RC-5392 Dust Cleaning Solvent Cat. NA-1004 $6.95 Another surplus stock purchase. Save a fortune over normal prices. Limited quantities. Be quick. ~ Cat Each 10+ • 16way PP-0952 $1.95 $1.65 20 way PP-0953 $2.20 $2.00 . 26 way pp.0954 $2.20 $2.00 ·· • 34 way PP-0955 $2.40 $2.20 DESOLDER TOOL Incredibly strong suction. One hand operation• automatic tip cleaner action. Supplied with Teflon tip. Given A1 review by Electronics Australia. Cat. TH-1820 Pack 4. 33pF, 39, 47, 56, 68, 82 Cat. RC-5393 Packs. lOOpF, 120,150,180,220,270 Cat. RC-5394 SAVE Pack 6. 330pF, 390,470,560,680,820 Cat. RC-5395 ONLY $1 Par.k 7. 0.001uF, 0.0022. 0.0033, 0.0047, 0.0056, 0.0068 C<.t. RC-5396 [Pack 8. 00082uF, 001, 0.022, 0.033, 0.047 ~t RC-5397 DELUXE 111.,ACKRACK CABINETS WITH HANDLES Conductive ·. Varnish $8.95 - ·1/ 10 of each value in each ack · Cat. NA-1012 $7 .50 $.l4.50 Quality and design functionability at a down to earth price. Give your equipment a real 1st class appearance. Removable top and bottom panels, black finish with high quality brushed anodised front panel. Handles and rubber feet supplied, along with screws, nuts, etc. to assemble. SEE CATALOGUE FOR ALL DIMENSION DETAILS· page 46 Front panel width• 305mm Cat HB-5380 $39.50 5+ $36.50 ea Front panel width - 401 mm Cat. HB-5381 $49.50 5+ $46.00 ea Front panel width • 481 mm Cat. HB-5382 $49.50 5+ $46.00ea Cat. HB-5383 $65.00 5+ $61.00 ea Cat. HB-5384 $75.00 5+ $70.00 ea CYCLIC (Endless Loop) TAPE PLAYER As featured in Silicon Chip March 1008 Simply record a message onto the unit (microphone not supplied) and you can have a message from 15-30 seconds long repeated continuously or when necessary. Built-in amplifier· only needs a speaker. Dimensions 70(W) x 56(D) x 45{H)mm Weight 86 grams Cat. YT-2720 :'111111~~"'1 NORMALLY $29.95 SAVE $4 <at> :::.:5 VfflEO LEADS Less 50% - 1/'2 PRICE BNC-PL259 1.5 metres Cat. AV-6512 CAR REMOTE CONTROL DOORLOC~G 4 Door Car Power Door Lock Kit PC BOARDS VERO TYPE STRIP Alpha numeric grid, pre-drilled 0.9mm, 2.5mm spacing 95mm wide x 3 handy lengths. 95 x 76mm Cat. HP-9540 $2.25 9f x 152mm Cat. HP-9542 $3.50 Cat HP-9544 9Jx 303mm $6.50 This kit consists of 2 master solenoids and 2 remote (masters for the front doors). Full wiring harness for all 4 solenoids. Also includes controller relay circuit (Cat. LR-8835 $26.95) which will adapt to our remote controller (LR-8820) so the system can be remote controlled. Cat. LR-8830 $169.50 Cat. Price $8.95 LESS 50%$4.48 PL259-PL259 1.5metre Cat. AV-651 4 Cat. Price $7.95 LESS 50% $3.98 RCA-PL259 ~:t.mA:::516 ~ Cat. Price $5.95 LESS 50% 2.98 \fireless Receiver/Trans mitter Separate Door Lock Actuators :1 you own a 2 or 3 door vehicle buy the items below for power 'ocking and remote control operation. Uaster Door Lock Actuator CIIEMISTRY Ferric Chloride Available in 2 sizes, easy storage, easy to use. childsafe plastic bottles. Directions for use supplied on the bottles. 200 grams - makes 1 litre Cat. NC-4251 $4.95 400 grams - makes 2 litres Cat. NC-4252 $7.95 Fitted with 5A microswitch which can be used to power slave dctuators. Supplied with comprehensive kit of hardware fittings to connect to door lock hardware. Dimensions 145(L) extended body x 28(W) x62(D)mm. Cat. LR-8832 $38.95 This product consists of a receiver module and two key fob transmitters. A press of the button on the transmitter causes 1 of the 2 output wires on the receiver to go momentarily 'high' with respect to -1 2V. This is used normally to control Cat. LR8830 4 door power lock kit. It can be used to turn car alarms on and off. Supplied with wiring directions. Cat LR-8820 $99.50 Designed for opening boots, and rear doors, etc. Complete with hardware. Cat. LR-8834 $46.95 Ammonium Slave Door Lock Actuator Power Lock Relay Persulphate Similar to above but no microswitch. Use for passenger door on 2 door car, if you only want drivers door to unlock like other doors. Cat. LR-8833 This relay will operate any of the solenoids used in above units Key operation or remote (with LR-8820) Cat. LR-8835 The alternative to Ferric Chloride. Mix contents (4tl0 grams) woth 1.5 Im s of hot water to etch ,, , , co~per board approx 500 sq/cm. ~ "-~"' Supplied in child safe bottle. Cat. NC-4254 ...,. '7;>-·- $36.95 $6.95 I•ORTASOL PORTABLE GAS SOLDERING moN STILL ONLY $39.95 A brilliant new concept In soldering ■ No cords, batteries or bottles ■ . rl Hard working, up to 60 minutes continuous use II Refills in seconds, uses standard Butane gas lighter fuel ,I Made in Ireland ~at. TS-1420 HEAD OFFICE 115 Parramana Road Concord 2137 Telephone (02) 747 2022 Telex 72293 FACSIMILE (02) 744 0767 **** !ilft~~~~~~~~=:::i1 Tips to suit 1mm Cat. TS-1421 $15.95 2.4mm Cat. TS-1422 $15.95 Heavy duty, tip temp up to 400°C l l Adjustable temp - equivalent to 10-60 watts rI No lea_kage current to sens1t1ve c1rcu1ts $29.95 : ;• • ~ ~0 : -; ; :: JP ~ ~ : ~IUl__ ,- , ; ·,· • • • ~ ~ l _ : _ :~;:--;: __ ;;'.:~~::~~::==-----11. MAIL ORDERS P.O. Box 185 Concord 2137 HOn.lNE 02 7471888 POST & PACKING $lO-S24 99 $ 3.75 FOR ORDERS ONLY S25 - $49.99 S 4·50 $50 - ~.99 $ 6.50 TOLLAlEE (008) 022 888 OVER $100 $8.00 ROAD FREIGHT ANYWHERE IN AUSTRAUA $13.50 MAIL ORDER VIA YOUR 1'.f SYDNEY · CITY PARRAMATTA CONCORD HURSTVILLE 117 York St 102) 267 1614Mon-Fri 8.30 - 5.30 Thurs 8.30 pm - Sat 9 - 12 355 Church St (Cnr Victoria Rd) (02) 683 3377 Mon-Fri 9 - 5.30 Thur~ R.30 pm - Sat 9- 4pm 115 Parrarnatta Rd (02) 745 3077 Mon-Fri 8.30-530- Sat8.30-12 121 Forest Rd (02) 570 7CXXJ Mon-Fri 9 - 5.30 Thurs 8.30 pm - Sat 9 - 12 GORE Hill BURANDA QlD MELBOURNE-CITY SPRINGVALE VIC 188 Pacific Hwy (Cnr. Bellevue Ave) (02) 439 4799- Mon-Fri 9 - 5.30 Sat 9 - 4pm 144 Logan Rd (07) 393 0777 Mon-Fri 9 - 5.30 Thurs 8.30 - Sat 9 - 12 Sh~ 2. 45 A'Beckett St City (03) 663 2030 Mon-Fri 9- 5.30 Fri 8.30- Sat 9- 12 887-889 Springvale Road Mulgrave (03) 547 1022 Nr Cnr. Dandenong Road Mon-Fri 9- 5.30 Fri 8.30 - Sat 9 - 2 11 THE WAY I SEE IT 11 By NEVILLE WILLIAMS HDTV: don't hold your breath but DAT could be a goer! The passing of time has served only to confirm my earlier opinion that the market is not ready for HDTV - high definition television. But a new development on the copyright front may signal the release of DAT (digital audio tape) recorders to consumers worldwide. In the April issue, I reprinted a letter from W .G. of Wentworthville, NSW, lamenting the fact that despite all the talk about high definition television, wider screens, 3D images and so on, modern-day TV systems are still shackled to the CCIR standards adopted in the 1950s and subsequently "set in concrete" by the PAL colour system in the 1970s. Said W.G: " Unless we break out somewhere along the line, we'll carry the whole antiquated box and dice into the next century!" And again: "If we continue to perpetuate the present standards by locking more and more services into them, they'll still be entrenched long after many or us have ceased to care". In responding to W.G's letter, I admitted to sharing his interest in emerging technology but not his impatience to see it adopted in the near future. 3D TV, in particular, was "a big yawn" , still bogged down in the developmental stage after decades of research. New technology would undoubtedly be adopted, I said, when it is " right for the situation" when the providers are convinced that there is something in it for them and when consumers either 90 SILICON CHIP need or want it, or are open to persuasion. Right now, we have difficulty enough putting our existing technology to best use, as illustrated by the problems of local redeployment into the UHF band and hassles about the MAC format, both here and overseas. A 6000-word letter This exchange prompted one of the longest and best written letters I have ever received from a reader. The writer, Keith Walters of Lane Cove, NSW, says that he's had multi-level experience in the television industry. Starting out in domestic TV servicing, he later specialised in repairing home VCRs. From there he moved into the "professional" video field, " sitting more or less between broadcast and home video". He subsequently became a technician in a broadcast video production facility, gravitating from that into his present position looking after the electronics of high tech film camera equipment. With that background, he feels that he can reasonably claim to know what he is talking about. Why should I question that claim? The initial 5 pages of his 13-page letter effectively support what I had to say in the April issue! The remainder focusses on an apparent presumption by the original correspondent, W.G., that the television industry could readily cope with the adoption of new standards, if only they/we had the mind to do so. Keith Walters - K.W. for short - insists that there is more to it than a few interim converters; that there are major technological barriers between present practices and the requirements of true high definition, wide-screen TV. That division helped resolve my dilemma as to how best to cope with a 6000-word letter. The answer: split it in two, and use the respective sections in successive issues, thereby leaving room for other current topics. Are we ready for HDTV? With W.G. firmly in his sights, Keith Walters says: "I am sick of hearing about the imminent arrival of HDTV and/or conspiracy theories as to why we haven't got it already. Personally, I don't believe that present day technology is up to the task of implementing HDTV in mass produced form. Even if it was, there are serious doubts about whether the public would show enough interest to cope with the chicken-and-egg stage. "The assumption is often made that, because wide-screen formats have been successful in cinemas, it must automatically follow that the same will apply to TV. There are serious flaws in this argument. "Most of the progress evident in movie-making techniques has been in response to threats posed by other entertainment media. "Silent films gave way to talkies, partly to win back audiences stolen by radio broadcasting. Similarly, the threat of competition from TV broadcasts in the '30s and '40s (in the USA) spurred the perfection of colour cinematography. Again, the threat of colour TV in the '50s promoted the introduction of wide screen formats. "What is often overlooked in a discussion of this type is the exC.fllent level of compatibility between all these developments. For the movie theatres, introducing the innovations wasn't too painful an exercise. "I don't know whether it was practical to convert earlier silent projectors to handle sound but even if the theatre owner had to buy or lease a new projector and sound system, the cost wasn't all that crippling. After all, they still used the same building, screen, seats, popcorn machines etc as before. And they no longer had to pay someone to play the piano! Alas, I can remember · Perhaps I can butt in here, as one who has the dubious advantage of being old enough to have seen the silent/talkie transition in close-up. Without labouring the point, I doubt that struggling picture show ownen, in rural areas would have been impressed at the time by talk of compatibility between the respective technologies. Many of them were glad enough to have two (not one) reasonably reliable silent projectors with which to put on a weekly or biweekly show without breaks between the 1000-foot reels. For them, acquiring and installing two sound projectors would certainly have been a painful, if not a crippling, exercise. Some had to settle for discarded projectors traded in by city theatres. And yes, others acquired sound head assemblies which had to be installed, somehow, between the bottom film gate and the take-up spool. These measures worked, mainly because a lot of the old-time Digital Stereo Colour TV Set from Akai Released late last year, this new colour TV receiver from Akai features digital signal processing, Teletext, an FST (flatter, squarer tube) stereo sound and 20 watts per channel audio power output. Two models are available: the 63cm CT2570 and the 70cm CT2870. proprietors and operators were bush mechanics on the side. And don't forget that projectors, adapted for sound, had also to be provided with constant speed drive to combat wow and flutter. And, down in the "auditorium", many of the old halls had to be provided with a proper ceiling or otherwise treated to suppress the worst of the echoes and prevent the sound from being drowned out by rain on the iron roof! I concede the point you're trying to make, K.W. but your observations a bout silent/talkie compatability sound a lot more convincing in 1989 than they would have done in 1929. But back to your letter: "With the introduction of colour features in the mid '30s there was no problem at all. They were released on the same 35mm format as black and white movies. Perfect compatibility. Wide-screen movies "Finally, with the wide-screen formats in the '50s, the camera manufacturers had come up with the anamorphic principle. In this, the 7:3 aspect ratio wide-screen image is deliberately distorted by the camera lens so that it fits on to a standard 4:3 film frame. A corresponding lens on the projector restores it to the correct aspect ratio. "Everything else remains the same, so the theatre owner only needs a new lens for the existing projector and a wider screen to enjoy the benefits of the new format. If the owner was unwilling to provide a wider screen, a different lens again allowed the wider format pictures to fit a standard screen, with reduced picture height but greater picture sharpness. '' Anamorphic 7: 3 movies had become pretty well standard by the early '60s and little has changed since then. Multi-channel Dolby sound is about the only worthwhile improvement in all that time and l doubt that many people even notice the difference". AUGUST 1989 91 THEWAYI SEE IT - CTD Here again, I feel that K.W. is short-changing reality by equating compatibility to an appropriate choice of lenses. In the auditorium, new large screens represented a considerable outlay and the cost was multiplied if the proprieter felt obliged to provide remote controlled masking for wide and conventional prints and for on-screen adverts. As a further complication, the existing projection light source could well prove inadequate for the larger screen, necessitating changes in the lamphouse. Frequently, large theatres with ornate prosceniums could not install wider screens without major reconstruction and expense. Some, like Sydney's now defunct "Regent", had to dismantle their "Mighty Wurlitzer" to gain extra width. Certainly, as K.W. suggests, theatres had the option of retaining the original picture width and reducing the height but it was very much a short-term expedient. Now back to Keith Walters: I-Max and Omnimax "What about I-Max and Omnimax and the other spectacular formats? My opinion is much like yours: interesting but not of any real entertainment value once the novelty wears off. It's fun going for a simulated roller coaster or helicopter ride but have you ever seen how ridiculous a close-up ,of a human face looks on one of those giant screens? "The principal reason for their lack of mainstream success is incompatibility - there's just no economical way your average cinema could adapt to one of these outlandish formats. "As for the movie studios, the cost of these developments over the years hasn't been prohibitive, either. Re-equipping for sound was probably the biggest step but not all that costly when you consider all the other equipment and personnel needed to produce even a low budget picture. "Equipment has never been a major cost component in making a film. Nowadays, camera equipment is nearly always hired; in fact, Panavision equipment is only available on that basis. The cost difference between shooting anamorphic for cinema release and 4:3 for television is generally quite small. The shots may have to be framed more carefully and wider sets built but these are not major problems". I grant that K.W. is much closer than I am to film production, but I nevertheless wonder whether film producers would see equipment needs in quite the same light. Overstated or not, his key theme is that technological evolution in the cinema industry, from B&W silents to wide-screen colour talkies, has been facilitated by a high level of compatibility and manageable costs. Lack of that vital ingredient stands in the way of IMax and Omnimax. In the case of television, standards have evolved to what we cur- .,.~~.;r..i;it:.1;: 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 rently have: PAL/SECAM/NTSC colour, complete with stereo sound, domestic VCRs and video cameras. But a huge and little appreciated compatibility gap stands between this and high definition, wide screen and 3D on both the receiving and transmitting side. Says K.W: Writing off TV sets "One thing that particularly annoys me about these self-appointed champions of new TV standards is the way they conveniently underestimate the working life of the average TV set - like so many accountants, depreciating its value down to zero over a few years for tax purposes. "For most viewers, the purchase of a new TV set is a significant investment and its working life is whatever length of time it continues to display a watchable picture, without involving unacceptable maintenance costs. "And what do I mean by a watchable picture? Anyone who has had practical experience in TV servicing will know the kind of pictures people are prepared to tolerate. In fact, absolutely optimum pictures are a rarity. Are all these people demanding higher TV standards? I think not. "And don't let's forget VCRs. Normal PAL broadcast video has a theoretical luminance bandwidth of over 5MHz. A good camera in a well lit studio will achieve this easily; many will better 8MHz. On a good receiver, 5MHz will give a very pleasing picture indeed. "On the other hand, standard VHS and Beta VCRs, of which over 300 million have been sold, have a usable luminance bandwidth of just over 2.5MHz - with a new tape in a near-new machine. Rental movies fall short of this. "If the viewing public were really dissatisfied with the results obtainable from our present system at its 5MHz best, it's hard to imagine how they could put up with the markedly inferior pictures delivered by the average 2.5MHz (or less) VCR. They do watch them, of course, and so do I. Larger TV pictures ••As for the demand for larger 92 SILICON CHIP screen sizes, surely if people were that desperate for larger pictures, they'd all buy 63cm or larger screen sizes. But that isn't what happens; 48cm and 51cm types seem to be more popular at present". Yes, K.W., many viewers do currently prefer smaller receivers but whether that can be interpreted as a long-term rejection of anything more pretentious is another matter. Such an assumption would ignore the "Jones factor" - the urge to keep up with the neighbours when they install a wall-mounted HDTV screen with accompanying surround sound. We mustn't overlook the power of marketing when theorising about what we are likely to "want" next year or the one after. How else do you think 300-million viewers decided, during the past decade, that they simply had to have a VCR? And how was it that compact discs swept LPs aside while audiophiles were still debating their merits? At this point, Keith Walters turns his attention to HDTV production technology which, he claims, is simply not understood by most people who write to and for technical magazines. If they did, they'd have taken more account of the fundamental disparity between composite colour on which our present system relies and component colour, which is the true basis of HDTV. They'd certainly have been less outspoken about the imminent adoption of HDTV. "As far as I am aware", he says, "no Australian TV network is even remotely interested in HDTV, apart from reading about it in professional trade journals". While K.W. would probably have picked up these vibes from his technical connections, two startling but hitherto confidential reports have just surfaced concerning the financial status of the three major Australian commercial networks. ("Our TV networks face big cash crisis" - the Sydney Sun-Herald, June 4, 1989). Accompanying graphs show an approximate 3:1 decline in share values for all three over the past two years, raising a large question mark over the billion-dollar "goodwill" ingredient in their respective balance sheets. · Faced with huge capital debts, ever-rising programming costs and involvement in the Federal Government's UHF/aggregation plans, TV broadcasters need a technological revolution like we need a hole in the ozone layer! But enough about television for this issue. Get up and got for DAT? Unlike HDTV, the DAT system is technically ready for the world hifi market but to date, has been released only in Japan because of conflict over software copyright. As a piece of gee-whiz technology DAT appears to work well - too well, in fact, for the compact disc manufacturers. They worry about DAT's capacity to make illicit multigeneration digital copies of their best releases, sonically indistinguishable from the original. Faced with the imminent release of DAT recorders a few years back, CD and software suppliers manag- IREECON '89 is The Convention ■ ■ MELBOURNE where the present - the future - and beyond come together. IREECON is for EVERYONE within the profession of electronics. SEPTEMBER 11 ·15, 1989 An electronics exhibition SHOWCASE not to be surpassed anywhere ■ ■ see the very latest equipment from electronic companies in the know, showing a VARIETY of technologies not available at one time under one roof at any other exhibition in Australia. You've seen the rest NOW see the BEST IREEC®n • CONVERGENCE HIGHLIGHTED • IREECON '89 incorporates a WEALTH OF FIRSTS for both exhibition .trade visitors and lecture program delegates. Those FIRSTS listed below are just the beginning - just take into account the countless FIRSTS on the exhibition floor. A significant AW ARD will be given for the best paper presented by a young engineer ■ ■ exhibitor product promotion presentations are open to everyone FREE of charge ■ ■ a technical lecture program which will open a window on the world of the 1990's and beyond. '~--.,_•i·•t B .~ l The Commercial Institution Unit o f 3, Radi 2 New o a ndMcLean Electroni St cs ( PO Engineers Box 79) Australia Edgecliff NSW 2027 (02)327.4822 - Fax (02)327.6770 - Publ x AA21822 (Quote User No. SYl35) t MONDAY, SEPTEMBER 11 - FRIDAY, SEPTEMBER 15, 1989 t A UG UST 1989 93 Multi-standard TV from Sony Sony offers a range of large-screen TVs that can handle multiple TV standards. The KV-2100WX is a 53cm model that is compatible with no less that 15 colour TV standards around the world. ed to win an undertaking from DAT manufacturers not to provide the facility to make a digital copy of any signal with a sampling rate of 44. lkHz. This would at least prevent consumers from making a direct digital/digital dubbing from compact disc to DAT cassette. DAT decks released to the Japanese domestic market conform to this agreement. It is still possible to make a DAT copy of a compact disc using the normal analog output from CD player and few would be able to pick the difference between it and a digital/digital dub. But theory insists that double DIA-AID processing must cause some degradation, even if negligibly small. Disc manufacturers could only hope that this niggling reservation, coupled with the high cost of DAT equipment, would encourage the public to buy original discs rather than rely on taped copies. It certainly seems to have had that effect in Japan, with Japanese DAT sales well down on what equipment manufacturers believe they would otherwise have been. With a question mark hanging over a 94 SILICON CHIP the future of DAT software, they see little point in releasing the equipment on the world market. The industry as a whole must undoubtedly accept some of the blame for the chronic disregard of copyright which is at the root of the present impasse. Illicit copying emerged as a major problem with the appearance of the compact cassette but after years of lipservice to copyright, manufacturers are currently offering dual decks and other facilities to make dubbing easier than ever! They can hardly complain if the public fails to see a moral difference between copying LPs and precorded cassettes onto compact cassette, and copying CDs on to DAT. Perhaps one should add: or on to recordable blank CDs, if and when these become a commercial proposition. A possible compromise Seeking a way around the problem, Philips have come up with with what they call "Solocopy". It involves restoring the 44. lkHz record/sampling rate to DAT decks but with a special provision: when recording at this frequency, a Solocopy deck would automatically insert into the data stream an extra bit of code - or a "flag". It would appear on the tape copy but would not compromise the sound in any way. Any attempt to duplicate the 44. lkHz DAT tape would be frustrated, however, because the flag would automatically abort the tape/tape re-copying process. Solocopy would permit the owner of a compact disc to make a digital copy of his own discs for his own use - which Philips, as a software/equipment supplier, regards as a reasonable expectation. But if a copy is made for a friend, that friend will not be able to provide a further copy for a further friend, thereby overcoming the problem of multi-generation digital dubbing. The scheme requires the fuli cooperation of disc suppliers, however, because if all DAT decks on the market were equipped with Solocopy, CD manufacturers would only have to insert the abort flag into the original data stream and DAT owners would be right back to where they currently don't want to be in Japan - an analog sourced copy or nothing. On the other hand, if disc suppliers do accept Solocopy, it might just get things moving for DAT on the international market. Equipment manufacturers would hopefully release the decks and well-heeled enthusiasts might buy them knowing that, one way or another, they could assemble a collection of high quality digital tapes. With decks on the market able to play 44.lkHz digital tapes, software suppliers may then be willing to implement what has always been their ultimate intention to release DAT recordings made from the same basic masters from which compact discs are currently sourced. Solocopy would then provide the same restraint on illicit copying as it would for compact discs: owners could copy an original DAT tape but copies of copies would not be possible. It's a compromise, but maybe, just maybe, one that could resolve the present impasse. ~ ******************* : BRAND NEW !! : NRP72 7.2V NICAD RACING PACK BATTERY Suits most Tamiya and other brand remote control cars, toys and models SPECIFICATIONS: Voltage: 7.3 volts Charging Current: 130mA Nominal Capacity: 1300mAH Charging Time: 15 hours S15025....................$39.95 NBC5 RACING PACK BATTERY QUICK CHARGER Fast charger for 7.2V Nickel Cadmium batteries • Input: 12V DC cigarette lighter - fuse protected • Output: standard racing pack lead and terminal to suit " NCRP72" and Tamiya 7.2V batteries • 0 to30 minute timer - standard fast charge is 15 minutes for "NCRP72" and other 7.2V batteries * ** •• • *• * *• *• * ** * PRODUCTS MULTI-CHIP PROGRAMMER CARD Model LP-A1 Module : Multi-Chip Good for programming • SAAM TEST 6116-62256 EPROM 8 BIT ICs • 2716-27512, 2716A-2751 2A, 27012-27012, 27C16-27C51 2, 2804-5,8064, 28256-52813 o • EPROM 16 BIT ICs , ' 271024, 27102, 27210 (,· • MCS-48 series of ICs 8741-8750, 8748-8748H, 8749-8749H • MCS-51 series of ICs. 8751-8752 X1 8020 ...... .. ..... 0nly 1' MIDI INTERFACE CARD - DS/401 The MIDI DS-401 Card is the PC standard MIDI interface that runs most popular PC music programs for sequencing, recording, composing, music print ing , patch editing , music instruction and many other applications. • Socketed EPROM for easy user replacement • 1/3 length (short) card will flt in any computer accepting standard expansion card , including laptops • Including "Y" cable, external connector box to tra nsport is unnecessary Run all programs designed for the Roland MPU-401 architecture At an Un believable price! * * ** . * $575 X181 64....... .. ........ $1 95 * * ** * ** * ** * *** * * ** * * 1·9 10+ $11 .95/Pk $10.95/Pk AA SIZE NICAD Nominal Voltage : 1.2V 450mAH Charging : 500mA, 15hrs S15020 1-9 10+ 100+ $3.95 $3.75 $3.50 CSIZE NICAD Nominal Voltage: 1.2V 1,200mAH Charging : 120mA. 15hrs S15021 1-9 10+ $11 .95 $10.95 D SIZE NICAD Nominal Voltage : 1.2V 1,200mAH Charging : 120mA, 15hrs S15022 1-9 $11 .95 • 41256•80ns U48262 ........ .......... $14.95 • 41256-100ns ROYEL SOLDERING STATION The all solid-state heat sensor and control unit allows the selection of the appropriate soldering tip idling temperature. The very high-powered element (relative to the size of the tool) will replenish heat drained from the tip during each soldering operation and will recover the tip tempreture moments after the tip is lifted. • Zero voltage switching • Zero tip potential • Au x ground connection • For soldering irons• CT6 (3mm Tip), CT7 (5mm Tip) T12570 ..................... $215 JUMP WIRE KIT (KS-350) Contains: 14 kinds of length from 0.1" to 5" with different colors 011278 ...... ............ $19.95 10+ $10.95 9V SQUARE TYPE NICAD Nominal Voltage: 9V 100mAH Charging : 14 hours at 10mA Note : equivalent brands may be supplied S15023 1-9 10+ $24.95/Pk $23.95/Pk 011264 ....................... $69 U48260 .................. $14.30 -- • 1MB•100ns U48265 ........ ............... $35 • Can be used directly to inject a signal into logic circuits without removing IC • Compatible with TTL, DTL, RTL HTL, MOS and CMOS ·• ·e··_--. :..r.··~1: . 0 11274.................. $42.95 . .. . .. RODIRVING ELECTRONICS All sales tax exempt orders and wholesale inquiries to : • Large display 4 1/2 dgt 0.5" height LCD with maximum reading of 19999 • Autom atic polarity."-" display fo r negative input • High over-load protection for all ranges • Over load display, the highest digit " 1" or ··-1 " alone glows • Power consumption 20mW approx. • Dimension & weight = 162 x 86 x28mm and 200g approx 01 1266 ..................... $199 SYDNEY: 74 Parramatta Rd. Stanmore 2048 Phone : (02) 519 3134 Fax: (02) 519 3868 MELBOURNE : 48 A·Beckett St Phone : (03) 663 6 151 NORTHCOTE : 425 High St . Phone : (03) 489 8866 ADELAIDE : (Eleclronic Discou nters) 305 Morphett St. Adelaide Phone : (08) 2 12 1799 MAIL ORDER & CORRESPONDENCE : P.O . Box 620 . CLAYTON 3 168 Order Hotline : 008 33 5757 (Toll free. strictly orders only) Inquiries : (03) 543 7877 Telex : AA 15 1938 Fax: (03) 543 2648 RITRONICS WHOLESALE : 56 Renve r Road , Clayton . 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Road Freighl. bulky and lragile items will be ch arged at differen t rates. Errors and omissions excepted. Prices and specifications subject to change . IBM' . PC' xr. AT" . a, e registered 1rademark.s ot In1ern at1 onal Bus ine ss Machines "Apple Is a re g1s te1 ed tradema rk Teflon · Is a r eg istered tradema1k ot Dup o nt · □ e nontes 1eg 1s te r ed 1rademarlo.s o!the1rres pect1ve owners [ES] VISA SILICON CHIP PRODUCT REVIEW - - - - - - - - - - - - - - - - - - - - The Metrix MX52 5000-count multimeter about those features it doesn't have rather than try and list all those it does have. Really, there is only one facility it doesn't have and that is the ability to measure capacitance. In a unit of this price range, capacitance measurements probably should be included but it does have a lot of other worthwhile peeled off to reveal the battery. features. We liked the battery compartParticularly noteworthy features ment. With most multimeters you are true RMS indication for AC have a 9V battery which is a poor voltage measurements, dB readings fit inside the compartment and fitfor relative AC voltage measureted with a snap connector having ments, frequency readings up to leads which are liable to break off. 500kHz, resistance measurements In the Metrix though, the compartup to 40 megohms and the 50-step ment fits the battery like a glove bargraph. and it has integral battery contacts Normal measurement mode is - no snap connector to fiddle with. auto-ranging although you can How often do you have to change · manually select a particular range the battery anyway? Estimated life by pressing the Range button. The is 500 hours but naturally this can MX5 2 has a whole host of annunvary depending on the pattern of ciators to suit the various measurement modes; these all come on use and the type of battery (alkaline momentarily in a self-test routine or carbon-zinc). One good point is that the meter turns itself off when you first turn the instrument on. automatically after 30 minutes if There is even a range where no you haven't made a measurement in annunciators are displayed. Selthat period. You don't realise how ected by the rotary switch, the good this feature is until you have ADP range has a full scale capabiliexperienced it - it saves a lot of ty of 500mV. It is intended for use batteries. with temperature probes, shunts, An equal amount of ingenuity has tachometers and other accessories been brought to bear in the design where the normal annunicators of the case of the Metrix. As would be inappropriate. already noted, the unit is totally sealed and the case is cunningly Bargraph designed to clip together. The 50-point bargraph has three Measurement modes separate modes of operation, all As with a number of top with an update rate of 10 times per multimeters available now, the second, which is about equivalent Metrix MX52 has more measureto the best response of an analog ment modes than you can shake a meter. Normally the bargraph stick at. It will take you quite a works like the pointer on an typical while to become familiar with all analog meter, moving rapidly up the modes. and down the 50-point scale to inIn some ways it is easier to talk dicate fluctuating values. In the market for a new all-singing all-dancing multimeter? How about this rugged new Metrix MX52 made by ITI Instruments in France? It is a 5000 count instrument incorporating a bargraph and featuring frequency, dB and RMS AC measurements. Metrix is a new name to the Australian market but it is part of the giant European conglomerate ITT. This new DMM is actually designed and manufactured in France where some unusual thinking has been brought to bear in its facilities and overall presentation. 5000 count, eh? This is a far cry from the normal 2000 count (actually 1999) of a typical 3 ½ digit multimeter. This means that for readings up to 4999 this multimeter gives 4-digit resolution. That can be quite handy in many situations. The MX52 is quite a hefty instrument as multimeters go, in both size and weight. It measures 189 x 82 x 40mm and weighs 500 grams. Combine that with the rubber feet on the rear of the case and it is not prone to being easily dragged off your workbench. Want to change the battery? Most multimeters have a compartment with a clip-out cover for access to the battery but the MX52 is totally sealed for high voltage isolation, even in wet environments. This means you just can't open up a compartment on the back. Instead, you first have to remove the "Secur'x" plastic fitting which normally locks the test leads into the sockets. Then you remove the tilting bail fitment and use it to lever off the plastic escutcheon which fits over the range selector switch. Under this lies the battery compartment seal which can be 96 SILICON CHIP The Metrix MX52 is a rugged 5000 count instrument with a host of features for the professional and serious user. It can measure frequency, dB and RMS AC voltages and also includes a 50-point bargraph display. In Zero mode, the bargraph acts like a centre-zero meter while in Zoom mode, the bargraph has a gain of 5-times for more sensitive indication of fluctuations . are memorised whilst displaying the current value. Finally, the Memory mode allows up to five values to be stored using the STD key and recalled with the RCL key. Digital display Logic mode The digital display can be operated in one of four modes. The Normal mode is what you would expect (ie, the actual value is indicated) while the Relative mode indicates the difference from a reference value which is stored when you press the REL button. The bargraph remains in the absolute value mode to show the actual value. Metrix call this the Live Trend Mode. In the Surveillance mode (LIM) the minimum and maximum values The logic function displays LO, HI and OPEN for digital circuits. It also has an audible tone facility which gives a high modulated (4kHz) beep for HI logic and a lower modulated beep (2kHz) for the LO condition. This feature is quite handy but it is not able to follow logic states which change at more than about once a second. The threshold voltage for the HI to LO logic transitions is 1.3V. Accuracy As with all other multimeters, the MX52 is most accurate for DC voltage measurements and less accurate for AC measurements, particularly as the signal frequency rises. For DC voltage, the accuracy is ± 0.1 % plus 1 digit. For AC voltage with signal frequencies between 40Hz and lkHz, the accuracy is ± 0.75% plus 2 digits; between lkHz and 5kHz it is ± 1. 7 % plus 2 digits and between 5kHz and 20kHz, the accuracy is ± 3 % plus 2 digits. DC current accuracy is ± 1 % plus 1 digit except for the 500µA, 50mA and 5A ranges where the accuracy is ± 1.2% plus 2 digits. AC current accuracy is ± 1.5% plus 2 digits from 40Hz to 400Hz; ± 2.5% plus 2 digits for 400Hz to lkHz and ± 3 % plus 2 digits from lkHz to 5kHz. For resistance measurements, the accuracy is ± 0.3% plus 2 digits except for the 5MO range where it is ± 0.5 % plus 1 digit and the 40MO range where it is ± 2 % plus 2 digits. Frequency measurements can be made from 10Hz up to 500kHz with an accuracy of 0.05% plus 1 count. The resolution, however, is limited since there are only four digits available on the display. By the way, all the above accuracies are with respect to the reading rather than the range full scale. So DC measurements are ± 0.1 % of the reading. dB measurements are accurate to ± 0.3dB from - 30dB to + 60dB. Conclusion Well, what more can we say. Once you become familiar with the instruction book which must be carefully read to understand how the various functions are brought into play, the MX52 works very well. It is obviously a well-made instrument and it is backed by a full 4-year warranty for parts and labour. Recommended retail price of the MX52 is $430.92 including sales tax. For further information and the address of your nearest dealer, contact Elmeasco Instruments Pty Ltd, PO Box 30, Concord, NSW 2137. Phone (02) 736 2888. ·~ AUGUST 1989 97 I PRODUCT SHOWCASE I cessory packs which give you more drills, wire brushes, cutting wheels and grinding wheels of various shapes. These are all useful if you are involved in any sort of modelling activity and you need to do drilling, polishing, engraving and so on. Our sample unit sells for $69.50 and came from Geoff Wood Electronics Pty Ltd, 229 Burns Bay Road, Lane Cove West, NSW 2066. Phone (02) 428 4111. Black rack cases with handles Arlec Supertool & accessories If you are working on printed circuit boards, the Arlec Supertool is very useful for drilling holes or cutting tracks. If that was the end of the story it would be a very handy unit but it also has a lot of accessories which add greatly to its usefulness. As it stands, it is supplied with a 12V DC plugpack, 4 high speed steel drills, 3 milling cutters, a small wire brush, a small emery wheel, 6 pencil erasers and a number of different sizes of collet chucks. You can also buy additional ac- High intensity siren for burglar alarms This high intensity piezoelectric alarm uses a re-entrant horn to give a quoted sound intensity of 120dB (presumably at a distance of 1 metre) for a DC input of 12 volts. Current consumption is 300 milliamps. Inside the housing, the unit has its own oscillator and drive circuitry and it produces a warble tone. The unit would be excellent for an indoor alarm or inside a car however it might not be loud or penetrating enough if used underneath the bonnent of a car. 98 SILICON CHIP Overall dimensions are 100mm wide by 85mm deep. Priced at $24.50, the unit is available from Altronics, 174 Roe Street, Perth, WA 6000. Phone (09) 328 1599. Jaycar has a range of five well finished black rack cabinets of aluminium construction. They have anodised front panels while the remaining panels are painted in matt black. Three of the cabinets are the standard 481 mm (19 inch) wide and the two larger of these have ventilation slots at the sides. The smaller cabinets are 401mm and 305mm wide respectively. The cases range in price from $39.50 for the smallest unit to $75 for the largest. In these days of high metalwork costs, these prices are quite reasonable. Weatherproof pH monitor This weatherproof pH monitor features totally sealed construction, including membrane switches, and is suitable for measurements in conjunction with an alarm or in industrial processes. The instrument Polystyrene capacitors YES Made here in Australia? YES Made Special to Type? features two control or alarm setpoint relays, an isolated 4-20mA recorder output, and an optional RS232 or RS485 serial data output. For further information, contact Amalgamated Instrument Co Pty Ltd, PO Box 134, Terrey Hills, NSW 2084. Phone (02) 450 1744. Cordless soldering iron from Scope YES Where From? Allied Capacitors Australia Alli~~ 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 1OpF 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. Interested? Call us now on: (02) 938 4690 OR Cut out and post this coupon to Post Office Box 740 Brookvale, N.S.W. 2100 This fancy looking cordless soldering iron is designed and made in Australia. It has a 60 watt rating and is powered from two nickel cadmium cells. On a full charge, it is capable of making between 40 and 140 solder joints. For further information, including prices and charger options, contact Scope Laboratories, PO Box 63, Niddrie, Vic. 3042. Phone (03) 338 1566. Portable hard disc plugs into your PC Many businesses must be concerned that so many of their valuable company records are locked up in the hard disc of one of their computers. It would be so easy for a ------------I 1 Yes, I am interested in your capacitors. Please post me details of the following values: I ... /.. .VDC... /. I Name I Add ress VDC ... / ... VDC ... /. VDC (Please print) -------------L~~~~~~~~~-~J ware, provided software commands were routed through the operating system. In text mode, the character size for VGA is 9 x 16 dots, thus producing a resolution similar to that of enhanced EGA cards, but not in the same way nor using the same range of colours. Using, for example, the PS/2 Display Adapter, a PC or AT can use all of the features of the VGA. While VGA is not as advanced as perhaps expected or wanted, it does provide good compatibility at the BIOS level with previous display adapters. The advances include a greater range of colours, however performance has not increased substantially. As with monitors, the evolution continues. ~ thief to break in and steal the machine and then all the confidential records would be either lost (if not fully backed up every day) or possibly made available to competitors. Now there is a viable solution available with Portadisk. This is a standard NEC 40 megabyte hard disc that fits into the normal 5¼-inch spacing on any PC XT, AT or 386 computer. When you go home, you just use the key to unlock the disc and unplug it - just like the removeable car radios now available from some manufacturers. The Portadisk comes with keylock and cabling and is easy to fit. The hard disc controller on most computers can support a second drive. Portadisk comes with a 3-month warranty and a 14-day money back guarantee. The introductory price is $1090 including sales tax. For further information contact Electronic Solutions, PO Box 426, Gladesville NSW 2111. Phone (02) 906 6666. Computer Bits ctd from page 84 AUGUST 1989 99 NEWPRODUCTS-CTD Stainless steel handtools from Jaycar Pictured are samples of a range of stainless steel handtools now stocked by Jaycar. All have cushioned plastic handles and they are spring-loaded for easy handling. Our picture shows a pair of side cutters and a pair of smooth grip long-nose pliers. Both are priced at $12.95. Also in the range is a combination wire-stripper, cutter and pliers which is well priced at $7.95. They're available at all Jaycar stores and stockists. Com£ortable headphones from Altronics Over the past few years there has been a revolution in headphone design but the emphasis has been on very small light phones which can often be fiddly to adjust and wear. These new headphones from Altronics are somewhat larger than the phones sold for use with portable cassette players but smaller than full size phones. They have non-removeable padded earpieces and the plastic headband is adjustable for comfortable listening. Nominal impedance of the phones is 45 ohms in each channel and they are quite sensitive, due to the use of samarium cobalt magnets in the earpieces. For convenience, the phones are supplied with a 6.5mm stereo jack and a 6.5mm to 3.5mm jack adaptor. They sound very good but without the very deep bass of circumaural phones (ie, those with a flexible seal right around the ears). Recommended retail price is $39.50. They are available from Altronics, 17 4 Roe Street, Perth, WA 6000. Phone (09) 328 1599. TV TEST EQUIPMENT --~- (AUSTRALIAN MADE) SHORTED TURNS TESTER Built in meter to check EHT transformers including split diode type, yokes and drive transformers. $78.00 + $3.00 p&p HI-VOLT AGE PROBE Built in meter reads positive or negative 0-50kV. For checking TVs , microwave ovens. $84.00 + $5.00 p&p. 1 l " TELE-TEST TUBE TESTER & REJUVENATOR Removes cathode grid shorts & rejuvenates picture tube. Suitable for all colour tubes 1 2 months warranty $420.00 + p&p. TV TUNER REPAIRS PYE LMD31 Turret repair only. . . $18.00 + $2.00 PHILIPS (ELC 2060) repair & exchange. . $17.00 + PHILIPS (UV 461) repair only ............ $18.00 + PHILIPS Turret repair & exchange . . . . $18.00 + AWA MITS Varicap repair only . . . .. . . .. . .. $18.00 + p&p p&p p&p p&p p&p Cheque, Money Order, Bankcard or MasterCard Y.V.TuNERs) 100 SILICON CHIP 216 Canterbury Road, Revesby, NSW 2212. Phone (02) 77 4 1154 Miniature digital switches with LED bacl<lighting These miniature pushbutton digital switches are available with either red, yellow or green LEDs for backlighting the numbers. The positive (increment) and negative (decrement) buttons are also backlit so that the switches can be operated in pitch dark if need be. The switches are small: only 18mm high and 6mm wide (per switch unit) and employ snap-in mounting. Switch rating is up to lO0mA at 28 volts DC with initial contact resistance of 200 ohms maximum. For further information, contact IRH Components, 32 Parramatta Road, Lidcombe, NSW 2141. Phone (02) 648 5455. ~ R. F. DEVICES PTY. LTD. SPECIALISTS IN INSTRUMENTATION & CALIBRATION "WHERE SERVICE IS NOT JUST SERVING" ... 20 MHz DUAL TRACE OSCILLOSCOPE QUALITY MUL TIMETERS AT AFFORDABLE PRICES KT-8801 • • • • • • LARGE LCD DISPLAY LOGIC TEST CAPACITANCE TEST TRANSISTOR TEST COUNTER INCLUDES SOFT CASE $115.41 $870.00 - INCLUDING: KT-8105 • COMPONENT TESTER • PROBES & ACCESSORIES • SALES TAX • • • • • • • OTHER BANDWIDTHS (15,35MHz) etc. AVAILABLE. ENQUIRE NOW 4 ½ DIGITS 0 OHM ADJUSTMENT CAPACITANCE TEST TRANSISTOR TEST QUARTZ CLOCK HIGH ACCURACY INCLUDES SOFT CASE $181.00 KT-8205 • • • • • • • ELDITEST SERIES 1000 MODULAR TEST PROBES • • • • UNIQUE " PLUG IN " MODULAR DESIGN ALL PARTS AVAILABLE SEPARATELY WEST GERMAN QUALITY & PRECISION ALL ACCESSORIES INCLUDED Type Part No. Attenuation ETS 1001 ETS 1002 ETS 1003 90 001 90 002 90 003 ETS 1011 ETS 10 12 ETS 1013 9001 1 900 12 90 0 13 1X 1X 1X 10 10 10 X X X 9011 1 901 12 90 11 3 1X 1X 1X / / / 10 10 10 X X X C (pF) Bandwidth (MHz) Risetime (nsec) Cablelength (m) PRICE $ same as Scope 45 70 100 20 15 10 15 20 30 1.2 2.0 3.0 10 10 10 15.0 16.5 19,5 100 80 60 3.0 4.0 5.0 1.2 2.0 3.0 48.24 61.20 67.68 57.48 81.72 89.28 1.2 2.0 3.0 55.80 105.48 114.12 1X ETS 111 1 ETS 1112 ETS 11 13 $184.00 Input Impedance R(MQ) 4 ½ DIGITS 0 OHM ADJUSTMENT TRANSISTOR TEST COUNTER QUARTZ CLOCK HIGH ACCURACY INCLUDES SOFT CASE 10 same 10 as 10 Sco pe 10 R. F. DEVICES PTY. LTD. SUITE 1A, 9 LYN PARADE, LURNEA, NSW 2170. X 1X 55 75 100 10 X 16 18 20 1X 10 X 1x 10 15 10 5 100 80 60 35 50 70 3 5 7 TOLL FREE: (008) 02 367 4 TELEPHONE: (02) 607 8811 FACSIMILE: (02) 607 3763 TELEX: 127948 X * ALL PRICES INCLUDE SALES TAX. * ENQUIRE ABOUT OTHER QUALITY TEST EQUIPMENT. * DISTRIBUTORS REQUIRED IN OTHER STATES. SUBJECT TO CHANGE WITHOUT NOTICE. VISA Diners Club lnrernariona/' PT.22: TIIE BENEFITS OF MODERN 3-PHASE ELECTRIC LOCOS THE EVOLlITION OF ELECTRIC RAILWAYS Up until very recently, the series DC motor has been king for electric traction. It has very high starting torque and will run over a wide speed range. But ultimately the series DC motor will be replaced by the more efficient 3-phase induction motor. By BRYAN MAHER Three-phase induction motors in electric locomotives are not new. They were used as far back as the 1890s and were traction supplied from 3-phase overhead trolley wires. But the only way to control their speed was by pole switching. This was clumsy, made for very jerky acceleration and would only let the loco operate efficiently at a few fixed speeds. So while a few countries persisted for some time with 3-phase traction, notably Italy (see Pt.8, SILICON CHIP, June 1988), all electric and diesel electric locos have used series DC motors which are relatively easy to control in speed and torque. Some locos have used low frequency AC to feed the series traction motors (notably the 25Hz US system) but whether the traction motors have used AC or DC, they all have the drawback of using brushes and either commutators or sliprings. Series motors for traction are also are large and very heavy. Their brushes and commuators require considerable maintenance and the ingress of moisture, dirt and brake dust to the motors causes lots of problems. Heavy traction motors also place a limitation on maximum operating speeds. Part of the motor weight hangs on the wheelset axle and this unsprung weight degrades the bogie riding quality over track undulations. Another big disadvantage of series DC traction motors is low efficiency at low speeds - they draw very large currents while the actual power being developed is quite low. This is a particular problem in diesel electric locomotives because the diesel engine has to run at high speeds to generate the high currents required at starting. This means that the alternator must be over dimensioned to deliver those very high starting currents. 3-phase squirrel cage motors Invented in 1888 by Nikola Tesla, squirrel cage AC induction motors have the highest power to weight ratio of any electric motor. Moreover, the rotor has a very simple construction, consisting of a simple laminated silicon steel core with slots carrying bare copper bars, all short-circuited together at both ends (very similar to a squirrel cage, hence the name) and with no insulation. Since the rotors are very robust INDUCTION MOTORS ARE very simple in construction as these photos of a stator and rotor show. Since there are no brushes, no commutator or sliprings, and virtually no insulation on the rotor, the motor is utterly reliable and the only maintenance required is infrequent bearing replacement. 102 SILICON CHIP and · have no brushes and no commutators they suffer very little damage from vibration and are virtually maintenance-free. Rotor faults are rare in 3-phase AC squirrel cage motors because of their simplicity of construction, whereas the incidence of breakdown in the armatures of DC motors is much higher because of their complex electrical structure. Rotating magnetic field The 3-phase currents supplied to the stator coils of an induction motor set up a rotating magnetic field in the air gap between stator and rotor (the stator is so-named because it is stationary). This rotating magnetic field spins at the so-called "synchronous speed" which is proportional to the supply frequency, and inversely proportional to the number of stator poles. For example, for a 2-pole motor on 50Hz supply the "synchronous speed" is 3000 RPM while in a 2-pole motor on 25Hz supply the magnetic field rotates at 1500 RPM. An induction motor always spins a little slower than the rotating magnetic field. Typically, a 2-pole motor on 25Hz supply at full load runs at 1450 RPM, only 3.3 % slower than synchronous speed. At no load such a motor can run as fast as 1495 RPM. Motor torque/speed The torque developed by a squirrel cage motor depends on the difference between actual rotor speed and synchronous speed. Fig.1 shows the example of a 2-pole motor on 25Hz supply. Maximum torque and best efficiency occurs at a speed about 3% less than synchronous speed. In effect then, induction motors run at a virtually constant speed. For stationary motors, as in factories and workshops, this is ideal for driving drills, grinders and other machinery. But for traction motors in locomotives the requirement is controlled variable speed with high starting torque at low speeds. Clearly, induction motors on a fixed frequency supply present big problems for traction use. 3-phase locomotives THIS MODERN DIESEL 3-PHASE shunting locomotive is made by Brown Boveri. Shunting locos require very high starting tractive effort and the 3-phase inverter drive system is ideal for this, giving fuel savings of more than 30%. a more or less constant speed on a fixed frequency AC supply, the obvious need for locomotive use is a variable frequency supply which would let them run at any desired speed. Using a 2-pole motor as an example, a very high running speed could be attained with the AC supp- ly set at 50Hz; half that speed at 25Hz, one quarter with a 12.5Hz AC supply and so on. For starting, where the highest torque is required, we could use an AC frequency as low as 1Hz or 2Hz. Maximum torque would then be exerted at zero rotor speed - ideal for starting a train. +TORQUE WORKING POINT ORIVING MOTORING ORIVE SUP ZERO TORQUE L-- - - ----1..!.45-00---J/ - 1 = 5 5 = 0 - - - - -- SP-EE - O-(R~PM-) 1500 RPM=/ SYNCHRONOUS SPEED BRAKE I sup-ni-~ WORKING POINT BRAKING - TORQUE FIG.1: THE TORQUE VERSUS SPEED characteristic of a typical 3-phase induction motor, this one being a 2-pole version operating from a 25Hz supply. Note that the motor operates efficiently over a very narrow rev range. If the speed is to be varied, so must the input frequency. Since induction motors do run at AUGUST 1989 103 THIS POWERFUL GERMAN LOCO uses 3-phase inverter drive and is rated at 5600kW (7500hp). Using a Bo-Bo axle arrangement, it weighs only 84 tonnes and yet generates a starting tractive effort of 340kN. As well, with a low frequency AC supply, the motor efficiency remains high even at very low rotor speeds. Though these facts have been well known for many years, the problem was how to achieve a variable frequency AC power supply with a capacity of several megawatts or more. The French railways made a creditable attempt with their class CC1400 electric locomotives of which 20 were built between 1955 and 1959. Though these showed the way for 3-phase traction, they were unsuccessful because the only way to achieve a variable frequency AC supply in 1955 was by a variable speed motor-alternator set carried in the locomotive. The advent of high power silicon controlled rectifiers (SCRs) opened the way to the design of DC-AC inverters which could produce 3-phase outputs with an approximate sinewave shape. These could work at any frequency depending only on the rate at which the SCRs are triggered. There was just one catch with the early high power thyristors. For locomotive use inverters of two to 10 megawatts rating are re104 SILICON CHIP quired and until about 1980 the highest available power thyristors were all too slow in response for inverter service. Nowadays, in their locomotives, the ASEA-Brown Boveri Company uses GTOs (gate turn-off SCRs) rated at between 2000 and 3000 amps and 2kV to 4.5kV, with switch-on times of 5-15µs and a current rise time of 500A/µs. The use of a single large GTO for each phase is preferred over multiple semiconductor devices in parallel for reasons of cost, weight and space. Traction circuit As outlined in previous articles in this series, typical electric locomotives operate from a single phase high voltage AC overhead supply of either 11, 15, 25 or 50kV at frequencies of either 16.6, 25, 40, 50 or 60Hz, depending on the system used in various countries. In every case a transformer steps the high voltage supply down to a convenient voltage of around 500V AC. This is then rectified and fed to the traction motors. The motors themselves are controlled in speed by varying their field currents or by varying their DC supply voltage. In a locomotive with 3-phase traction motors the high voltage step-down transformer and rectifier are still required but in this case the DC supply is regulated to a constant voltage. This voltage feeds a DC-to-AC 3-phase bridge inverter which uses 6 large fast GTOs, 6 large free-wheel diodes and associated trigger components. The general circuit arrangement is shown in the diagram of Fig.2. The 3-phase AC supply provided by the inverter drives all traction motors in parallel. The frequency of this AC thereby determines the motor speed and this is directly variable by the driver's speed controller. Either 4 motors in a Bo-Bo locomotive or 6 motors in a Co-Co machine are used. Starting voltage Well, now we have a 3-phase inverter system which will let the induction motors run at any speed but there is another problem. Because the current of an induction motor also depends on inductive reactance [which is proportional to frequency), it will tend to draw a lot more current when the frequency is lowered. That's just what we don't want. HIGH VOLTAGE, SINGLE PHASE AC OVERHEAD LINE +2kVOC REGULATED BUS HARMONIC FILTERS OC-AC 3-PHASE INVERTERS 3-PHASE VARIABLE FREQUENCY MOTOR BUS 6xGTO OVDC BUS RAIL ALL TRACTION MOTORS IN PARALLEL FIG.2: THE ELECTRICAL CONFIGURATION of a 3-phase electric locomotive. The high voltage single phase supply is stepped down in the main transformer, rectified and regulated to 2kV DC and then fed to the solid state 3-phase inverter. The inverter output is continuously variable to frequencies of less than 1Hz. This allows the induction motors to generate very high starting effort, while only drawing modest currents. , - - 3~~~TB[Ri~~ii ~ POL YPHASE THYRISTOR BRIDGE RECTIFIER + 2kvDc REGULATED Bus DC-AC 3-PHASE INVERTERS 3-PHASE VARIABLE FREQUENCY BUS OVOC BUS ALL TRACTION MOTORS IN PARALLEL FIG.3: IN A DIESEL 3-PHASE electric loco, the inverter effectively decouples the alternator from the traction motors and lets the diesel engine operate at the optimum speed for minimum fuel consumption. The alternator can be smaller too, because it does not have to supply very high current at starting. So at the same time as the AC frequency is reduced to achieve low speed, the voltage at the motors must also be reduced. This is achieved by pulse-width modulation of the GTOs. Thus at low speed the whole system is operating on reduced voltage and hence greatly reduced power, while still being able to produce high tractive effort. This means that the efficiency of the locomotive is high even at the lowest speeds. This important characteristic is in stark contrast to all other types of locomotive drives using commutator motors on either DC or single phase AC. Ideally, railway systems would like a single locomotive class having both high speed and high power so that one class can handle all jobs from heavy freight to express passenger. The older ideas of separate passenger and freight loco classes is inefficient in terms of plant usage. Now, with 3-phase induction motors able to operate over a very wide range of speeds, and with very high starting tractive effort, one loco class is possible. As an example of this, consider the E120 class 5600kW Bo-Bo locomotive on the German Federal Railway. It is equally suited to pull- ing a 2700 tonne freight train on gradients up to 5 o/o and speeds up to 80km/h or pulling fast passenger trains weighing 550 tonnes on gradients up to 2.5% and speeds up to 200km/h. All this is possible without changes to gear ratios. Thus, this loco is able to do the work of previous 6-axle freight locos or high speed 4-axle passenger locos. The 3-phase induction motors are considerably lighter than series DC traction motors of the same power ratings and they can deliver higher tractive effort without the time/ temperature limits of DC motors. AUGUST 1989 105 THIS INTERESTING AMERICAN locomotive is diesel powered but can also be electrically powered via a 3-rail system. The 3-phase inverter drive system allows the engine to run at low speed while still giving very high tractive effort. DC locomotives And what about DC electric railways where the overhead supply is 1500V DC such as in New South Wales? Three-phase traction motors can still be used. For this application a circuit similar to Fig.2 is used without the transformer and bridge rectifier. Instead the DC overhead line voltage is fed via a DC chopper thyristor to provide the regulated DC voltage supply for the GTO DCAC 3-phase inverter. Three-phase motors follow as before. The reason the DC overhead supply cannot be directly connected to the inverter is that the inverter must run from a regulated supply. In DC overhead systems, the line voltage varies widely depending on train loadings and distance from the substation. The future use of 3-phase traction motors thus opens up the prospect of locos with even higher tractive effort than the 86-class locos featured in last month's episode, without the need to deliver the extremely high starting currents of thousands of amperes. Diesel electric Where 3-phase traction motors are applied to diesel electrics using 106 SILICON CHIP this inverter system, big advantages apply. The electrical system is the same as described above except that the diesel engine, alternator and thyristor rectifier bridge provide the DC supply. Fig.3 shows the details. Besides being ideal for high speed diesel electric locomotives, this system has outstandingly high efficiency at starting and very low speeds. The 3-phase inverter system effectively decouples the diesel engine and alternator from the traction motors. This brings about a number of advantages apart from those already mentioned. Since the diesel-powered alternator no longer has to provide very high starting currents for the traction motors, it does not have to be as large or as heavy, for a given total output rating. Not only that but the system can be designed so that the diesel engine operates at a speed which gives the optimum specific fuel consumption for a given tractive effort. This is a particular advantage in shunting locomotives and can lead to fuel savings of more than 30%. Power factor In electric locos with 3-phase motors, this system can also be used to correct the total locomotive power factor. This in turn means less voltage drop and power loss in the overhead line, thus reducing the size and cost of the trackside transformers required. In large railway systems, this power factor improvement reduces costs all the way back to the power station itself. Wheel slip/slide Fig.1 also points up a unique advantage of 3-phase traction motors in the very steep slope from maximum torque at full speed to zero torque at slightly higher speed. This crucial fact implies that all the 3-phase motors in a locomotive are automatically forced to run at the same speed, since they are all supplied at the same frequency (at any one setting of the driver's speed controller). Should one wheel set lose traction and attempt to run faster than the others, that traction motor can never run faster than synchronous speed. So uncontrolled wheel slip is impossible. This excellent characteristic is far in advance of older locomotives using DC traction motors. It results in greatly reduced wear on the wheels and rails. When all the advantages of 3-phase variable frequency induction motors are added up, we have an ideal locomotive. No other motor system can provide full torque at standstill without damage. However, the catalog of advantages is not quite finished. Regenerative braking In contrast to locomotives running from a high voltage AC supply and using DC series motors, locos using 3-phase motors (as in Fig.2) can apply full regenerative braking without contactors, switches or any change in connections. The inverter system needs to be modified with additional SCRs but when this is done, regeneration can feed power back into the high voltage supply wire. The moment a train tends to run under gravity or momentum above the speed called for by the driver's controller, the motor immediately becomes an asynchronous alternator. The power generated is fed back via the inverter and thyristor bridge to the transformer where it is stepped up to overhead line voltage. This regenerative action has a braking effect on the train, right down to zero speed. THREE-PHASE TRACTION MOTORS are also ideal for use in diesel-electric locomotives. This Di-4 type loco from the Norwegian State Railways uses a CoCo axle arrangement and is rated at 2450kW. As an alternative, the power produced from regenerated power can be dissipated in braking resistors or used for heating on passenger trains. Our photos show some of the many applications of locomotives using 3-phase traction motors. Both diesel electric and electric locos in all sizes from shunters to main line high power machines have fully validated the concept. Acknowledgements The author thanks Lars Persson, Paul Bennet, ASEA-Brown Boveri, ASEA and ABB Journals for data, photos and permission to publish.~ ABOVE: A COMPLETE 3-phase inverter with a rating of 1420kVA (dimensions in millimetres). With four of these connected in parallel, a loco of 4450kW (6000hp) can be powered. Right: induction motors do not slip, even if the track is deliberately oiled. This is because the motors can never run at more than synchronous speed. AUGUST 1989 107 ASK SWCON CHIP Got a technical problem? Can't understand a piece of jargon or some electronic principle? Drop us a line and we'll answer your question. Write to: Ask Silicon Chip, PO Box 139, Collaroy Beach, NSW 2097. UHF switch has too much range I have made three UHF remote switches for car alarms (as described in the March 1988 issue) for my parents' cars and because all three have the same code, we have problems. When we go to turn one alarm on or off, the vehicle parked beside it sometimes turns off or on as well. Is there any way I can detune the transmitter so it is not so powerful and only has a range of 30cm to 50cm? I realise I could put them on different codes but since any one of us may drive any of the three vehicles, we would each need to carry two or three transmitters. (K.W., Townsville, Qld). • Over the last 12 months or so we have had quite a lot of correspondence on the UHF remote switch and many of the letters have complained of insufficient range. Problem with Speakerphone I am writing to ask for help with the Speakerphone kit published in the September 1988 issue of SILICON CHIP. When the volume control is turned all the way up, the dial tone is barely audible. Also, the microphone provided with the kit has only two terminals yet the wiring diagram indicates three wires going to the microphone! {A.W., Bansia Park, SA). • The first thing you should do is go back over your work and carefully check all the resistor values around the MC34018 IC. Some of those resistor values are quite critical. For example, if you substitute a 4. 7k0 resistor for the 4.3k0 resistor on pin 26 {RXO), you'll get exactly the symptoms described in your letter. 108 SILICON CHIP Yours is the first complaining of too much! Have you thought of swapping yours for some of the faulty ones built by other readers? Seriously though, it is an easy matter to reduce the range but we would not do it by detuning the transmitter. Instead, detune the receiver by rotating the slug L1 so that the transmitter has to be brought closer to trigger the unit. Coolant level alarm circuit I would like to comment on the letter from G.H. in the June issue of SILICON CHIP. Being a mechanic by trade, I too have seen motors ruined by a lousy water hose or fan belt. I have a few comments about your reply. First, the alternator warning light usually gets ignored by Mr Average. The fact that it says BAT or CHG or has a battery pictured does little to If that doesn't solve the problem, check the circuit around Q4. This circuit couples the received signal from the phone line to the receive input {pin 27) and to the receive level detector {pin 7) on the MC34018. Of course, the problem could also be due to a bad solder joint. The microphone you have been supplied with is OK - just wire it in as per the circuit diagram. If you look closely at the back of the microphone, you will probably find that one of its terminals is connected to the metal case. This terminal goes to the 2.2k0 resistor while the other terminal goes to pin 21 (VB) of IC1. A 3-wire connection is made to the microphone only if one of the terminals isn't earthed. In that case, an extra lead is run from the microphone case to the earth track as shown on the wiring diagram. worry most motorists if the car is still running. Second, the temperature rise in hot weather can be awfully fast without the water pump and fan working. When the temperature rises, water (coolant) pours out of the radiator cap and into the reservoir if fitted. So monitoring the reservoir level won't work in all cases. Hoses can blow and even welch plugs can blow out sometimes. Manufacturers love selling new parts at extortionate prices so we would have to wait forever to see a complete engine monitoring system. A fan belt monitor could be made to detect the presence of AC from the alternator windings. This monitor could sound a buzzer for 30 seconds before shutting down the engine by cutting power to the ignition. Perhaps even monitoring the under-bonnet temperature rise would do the trick. Or how about an oil temperature monitor. Here is a suggestion for a project. I have never seen a decent engine analyser - just the usual tacho, dwell and volt types. Why not design a machine around a small b&w TV set. This should give onscreen readout of tacho, dwell, volts and the HT as for the commercial units. (A.G., Nanango, Qld). • Your comments on the loss of water from car radiators puts a different complexion on the subject. We'll have a look at the situation a bit further down the track. Thanks also for your suggestion for an engine analyser. In£ormation on loop systems As far as I'm aware, the usual practice for loop systems is to make a single loop from figure-8 lighting flex and connect the ends to make two (electrical) turns. You can drive the loop how ever is convenient, the power required Tachometer won't work with high energy ignition C 1k TO POINTS TO POINTS --------------CHASSIS Fig.1: basic impulse tachometer circuit. It's operation is explained in the text. I recently installed a high energy ignition system on my car (an MG-A), as described in the May 1988 issue of SILICON CHIP. I am very happy with the system but now the Smiths impulse tachometer does not work. The instrument makers I have spoken to about this problem say the tachometer needs a new board, if they can get one (which is doubtful) at a cost of $120. Do you have any idea how to get around this problem? If it is not able to be fixed, maybe a warning should be placed on the kits to this effect. (V.B., Beaumaris, Vic). • Before explaining the problem, let's first consider the basic circuit for a typical impulse tachometer. Fig.1 shows for a 250-seat loop being between 10-30 watts. One word of warning though - don't place a dynamic microphone within the loop. Supersonic feedback tends to frizzle most amps to a crisp! Obviously the more turns the better and telephone-type cable may well be an economical alternative. I've used 3-pair telephone cable buried underneath a steel reinforced floor for a small (70 seat) section of a hall, and driven that with about 3 watts. Lastly, if you're using a 100/70 volt line line setup and your loop impedance (essentially the DC resistance) is around 2n don't despair - simply connect it between the an and 16Q taps. (J.L., Gosnells, WA). Fig.2: this simple circuit can be used to drive an impulse tachometer circuit when electronic ignition is used. the details. It uses a zener diode to clip the high voltage pulses from the points. The clipped pulses are then differentiated by a series capacitor and fed to a bridge rectifier and meter. In the High Energy Ignition System, the points act only as a switch and transistor Ql takes over the arduous job of switching the coil current. This means that your impulse tachometer must now be connected across Ql instead of across the points (ie, to the negative side of the coil). If the tachometer still does not respond, it may be because it relies partly on the primary resonance in the coil after each spark. Because the coil is reenergised at between 1 and 2 milliseconds after the beginning of each spark, this primary resonance does not occur. The way around this problem is to add an interface circuit between the points and your impulse tachometer. Fig.2 shows our suggested circuit. It uses the primary winding of a small mains transformer, type PF 2851 or equivalent. This is switched by an MJE340 transistor (Q2}. The coil voltage is limited by the .033µ,F capacitor connected between the collector and emitter of Q2. Q2 is driven by Ql which merely inverts the signal from the points. While we have bench tested this circuit, we have not actually tested it with an impulse tacho. Give it a try and let us know how it works out. excessive noise can do to their hearing. (E.C., Fairy Meadow, Wide range sound level meter NSW). I would like to see a constructional project for a sound level meter with progressive dB calibrations from O to 160dB. It should have the most important features associated with expensive commercial units, namely flat and Aweighted responses. It should also be portable and small enough to be hidden from doormen in a concert situation, as they don't take kindly to these devices. I know this is a bit demanding but it would surely be a popular project among readers. I am concerned at the ever increasing sources of loud noise being generated in our society and would like to make people aware of what • We agree that the level of noise produced by many rock bands and discos is really excessive but you're a game man if you are going into a concert to point out how loud it is to the patrons - they go there to be bombarded. Indeed many people think that unless the music is loud enough to drown out everything then the sound system isn't any good. , As far as the idea of a sound level meter is concerned, we are a bit wary of such a project. For a start we don't think that such a huge measurement range is necessary or practical. After all, anything over 120dB is painful. Calibration would AUGUST 1989 109 Problem with UHF remote switch I recently built the UHF Remote Switch, as described in the March 1988 issue, and combined it with the car burglar alarm described in the previous February 1988 issue. It all went together quite well except for one aspect. I found that I could turn the burglar alarm on with the remote control but I could not turn it off unless I waited for five minutes or so. A friend of mine then suggested that I short out the lOµF capacitor associated with the "Off" output for the remote switch. I did so and it worked like a charm and I could switch the alarm on and off at will, as quickly as I liked. Is this a legitimate modification? Also, when I was checking out the UHF remote switch, I checked the voltage output from the 8V 3-terminal regulator and my As you can see, the 20-channel stereo equaliser is featured in this very issue of SILICON CHIP. digital multimeter gave a reading of 10.5 volts. I thought I must have blown the regulator so I bought and fitted a new one but the new one measured the same. My mate's multimeter measured the voltage at exactly + 7.99 volts so it looks like my digital meter is cactus. Is it worth repairing and how do I go about it? (P.B., Penrith, NSW). • Yes, that is a good modification to make to the UHF remote switch. The capacitor needs time to discharge before you can turn the alarm off and with hindsight, the capacitor is not needed. As far as your multimeter is concerned, don't despair. We would lay "London to a Brick" that the battery in your meter is flat. Try a new battery in it and then make comparison measurements with your friend's meter. A lot of multimeters will give exaggerated voltage readings when their batteries go flat, while still appearing to work normally. Replacement for electronic ignition I also present a big problem. We also doubt whether we could design a unit which would perform better for the price, than Tandy's sound level meter which currently retails for under $60. It will measure up to 126dB and has A and C weighted responses. Speakerphone not loud enough Some months ago I built the Hands-Free Speakerphone fl'.om a Jaycar kit. I must say that it has been a great help around my small office. However, lately people who ring in complain that it sounds like I'm "down a well" or that the sound at their end is very faint. Do I have a microphone problem? I filled the back with plasticene in some heatshrink tubing as your article suggested and also reversed the connections to the microphone (at the board) in case it was possible to wire it back to front, but the hard-to-hear condition persists. All voltages are OK (as shown in the article) and the receive section 110 SILICON CHIP is fine - loud and clear. Incidentally, when I switch the unit on after answering an incoming call, I get what I imagine is bad acoustic feedback from the speaker if the volume control is advanced beyond half way. This persists until I hang up the handset to use the Speakerphone only. I have learned to live with this by keeping the volume down initially but I mention it in case it may give you a clue. Congratulations on your magazine. As a hifi buff I look forward to your 20-channel stereo equaliser. (P.S., Qld). • Your Speakerphone is working exactly as it should. A feedback howl or whistle is quite normal if the telephone handpiece is offhook. You can reduce the echo effect as far as the party at the other end of the line is concerned by placing the Speakerphone on a piece of thick carpet or felt. If need be, you can increase the transmit gain by reducing the resistor on pin 2 of the MC34018 IC to 30kn. This can easily be achieved by shunting the existing 91k0 resistor with 47k0. The electronic ignition system in my Mitsubishi Sigma has failed and the cost of a replacement electronic module is close to $150 which has rather horrified me. I was wondering if I could adapt the high energy ignition system published in the May and June 1988 issues to my car. I have a real problem though, because my car uses a reluctor pickup and I'm not sure how to install a Hall Effect pickup. Can you help? • The May 1988 issue carried two pages of technical data on the Motorola MC3334P IC and this included a circuit featuring a reluctor pickup. We understand that a number of readers have used this circuit to do what you want to do; ie, replace a dud ignition in their car. Apparently, it works like a charm. The reluctor circuit also has the advantage of a dwell optimisation feature which reduces the power dissipation in the coil at low engine speeds. The circuit can be accommodated on the printed board published in the May 1988 issue. Why disconnect the battery lead? Like your correspondent D.A. of Finden, SA (SILICON CHIP, June 1989), I too have puzzled over the need to disconnect the live battery lead when charging the battery in a car using an external charger. My guess is that this stems from the fact that it is common practice to connect the charger to the battery cable lugs. A faulty connection between one of the battery cable lugs and its battery terminal post could result in the peak no-load voltage of the charger being applied to the car's electrical system. (J.E., Bullcreek, WA). • Yes, that sounds like a reasonable explanation, particularly for older cars. However, the electronic equipment in most modern cars should be able to withstand around 20V without damage. ~ December 1987: 100W Power Amplifier Module; Passive lnfrared Sensor; Universal Speed Control and Lamp Dimmer; 24V to 12V DC Converter. February 1988: 200 Watt Stereo Power Amplifier; Deluxe Car Burglar Alarm; End of File Indicator for Modems. March 1988: Remote Switch for Car Alarms; Telephone Line Grabber; Endless Loop Tape Player. April 1988: Walkaround Throttle for Model Railroads; pH Meter for Swimming Pools; Slave Flash Trigger; Headphone Amplifier for CD Players. May 1988: Optical Tachometer for Aeromodellers ; High Energy Ignition for Cars ; Ultrasonic Car Burglar Alarm . June 1988: Stereo Control Preamplifier; Breakerless Ignition For Cars; MegaFast Nicad Battery Charger. July 1988: Fitting a Fuel Cut-Off Solenoid; Booster for TV & FM Signals; The Discolight Light Show. August 1988: Remote Chime/Doorbell; High Performance AC Millivoltmeter; Getting the Most Out of Nicad Batteries. September 1988: Hands-Free Speakerphone; Switchmode Charger for 1 2V Gel Batteries; Vader Voice. October 1988: Stereo FM Transmitter; High Performance FM Antenna; 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: 1 20W PA Amplifier; Diesel Engine Sound Generator; Car Antenna/Demister Adaptor; SSB Adaptor for Shortwave Receivers. January 1989: Line Filter for Computers; Proximity Detector for Cars; How to Service Car Cassette Players. February 1989: Transistor Beta Tester; Minstrel 2-30 Loudspeaker System; LED Flasher for Model Railways. March 1989: LED Message Board; 32-Band Graphic Equaliser; CD Compressor; Amateur Band FM Receiver. April 1989: Auxiliary Brake Light Flasher; Telephone Bell Monitor/Transmitter; LED Message Board Pt.2. May 1989: Electronic Pools/Lotto Selector; Synthesised Tom-Tom; Biofeedback Monitor For PCs; Simple Stub Filter For Suppressing TV Interference. June 1989: Touch-Lamp Dimmer; Passive Loop Antenna For AM Radios; Universal Temperature Controller; Understanding CAO Probes. July 1989: Exhaust Gas Monitor; Extension for Touch-Lamp Dimmer; Mains Hum Sniffers; Ultrasonic Car Burglar Alarm . Note: stocks of December 1987 & February 1988 are now very low. November 1987 and January 1988 are now sold out. ~ .---------------------------------- + -- 7 Use this handy form to order your back copies Please send me a back issue for: D December 1987 □ February 1 988 □ March 1988 □ April 1988 □ May 1988 □ June 1988 D November 1 988 □ September 1 988 D February 1989 □ October 1 988 D April 1989 □ July 1988 □ August 1988 □ December 1 988 D January 1989 □ May 1989 □ June 1989 □ March 1989 D July 1989 Enclosed is my cheque/money order for $ _ _ ____ or please debit my □ Bankcard □ Signature _ _ _ _ _ _ _ _ _ _ Card expiry date_ _ / __ / _ _ Name__________ ______________ _ □ Visa Card MasterCard Price: $A5.00 each (includes postage). Overseas orders add $A 1 .00 per issue for postage. NZ & PNG orders are sent by air mail. Detach and mail to: SILICON CHIP PUBLICATIONS Stree..__ _ _ _ _ _ __ __________ ______ PO BOX 139 COLLAROY BEACH Suburb/town _ _ _ __ _ _ _ _ _ _ _ _ Postcode_ _ _ _ NSW 2097 L _____________________________________ (PLEASE PRINT) I AUGUST 1989 l I J 111 T CEN'l Cash in your surplus gear. Advertise it here in Silicon Chip. CLASSIFIED ADVERTISING COUPON Advertising rates for this page: Classified ads - $7.00 for up to 15 words plus 40 cents for each additional word; Display ads (casual rate) - $20 per column centimetre (max . 10cm). Print your advert on a separate sheet of paper and send it with this form and your payment to Silicon Chip Classifieds, PO Box 139 , Collaroy Beach , NSW 2097. Fax: 982 9553. Name ........ ... .. .. .. ..... . .. .. .. ... .. ........ ... .... .. . .. ..... .. ............. . Address ......... .... ..... ... .. .. . .. . Postcode Suburb/Town .. Enclosed is my cheque or money order for $ Bankcard O Visa Card D MasterCard . ......... or please debit my 0 Card No I I I Signature ...................... .. .......... ..... ...... ................ Card expiry date ...... ./ .... .. ./ FOR SALE BUILD YOUR OWN LED Moving Message board. $ 7 5 for a 4-character display experimenter's short form kit and $1 50 for 16 characters. Kit consists 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. RADFAX 2: HI-RES WEATHER fax, Morse and RTTY receive program for MEMORY CHIPS D RAM PRICES AT 4th July 1989 Type 256 150ns -120ns -1 00ns -70ns 1Mb x 1-1 00ns -80ns 1Mb Simms 1MB x 8-1 00ns x 8-100ns x 8.80ns Suitability X7's Al's 386's 20MHz AT-386 Supers Price ex tax $6.60 $6.90 $8.00 $11.50 $22.50 $23.75 PS2's Mac Fast 386's $280.00 $267.50 $305.00 Discounts on large orders Sales Tax add 20% PELHAM Tel (02) 427 0011 Fax (02) 428 5460 112 SILICON CHIP IBM PC/XT/AT on 360K 5.25-inch floppy plus full documentation. Needs 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 $35 each plus $3 postage . Only from Michael Delahunty, 42 Villiers Street, New Farm , Old 4005. Phone (07) 358 2785. PRACTICAL ELECTRONICS, 1 9801988 inclusive. Everyday Electronics, Talking Electronics (130 magazines). Magazine holders, cost $7 .50 each (8). $95 the lot. Phone (03) 434 2945. EPROM PROGRAMMER for Commodore 64 . Programs 2716 to 27512 EPROMS . Plugs into user port, uses intelligent algorithms, LED function indicators. Software included . $220. Phone (02) 670 3700. WANTED WANTED TO BUY: North Star Advantage. Phone Robert Armstrong (049) 59 2400. WANTED: WIRELESS WEEKLY and Listener In magazines, radio service magazines, Practical Wireless cigarette cards . Contact Orpheus Radio Museum, RSD 898, Ballarat 3352. Advertising Index Adi lam Electronics ....... ....... IFC Allied Capacitors ... .. .. .. ......... 99 Altronics .. ...................... 72-75 Arista Electronics .... ..... .. .... .. 21 Bose Australia .... .... ............. 33 Dauner Electronics ............. . 65 David Reid Electronics .. .. . 53-60 Dick Smith Electronics ..... 38-45 Electronic Solutions ....... ..... 4 ,5 Elmeasco .. .. .. .. . .. .. .. .. .. .. .. . OBC Esckay Printernet .. .. ............ 7 9 Geoff Wood Electronics ..... .. . 67 Gold star .. .. . .. . .. .. .. .. . .. .. .. .. .. .. 1 7 Hycal Instruments .. .... .......... 65 IREE .. .... .... .... .... .... ..... .. ..... 93 Jaycar Electronics ......... . 22-25 86-89 J.V. Tuners .... .... .. ............. 100 PC Marketplace ...... ........ 80,81 Pelham ........ .. .. .. ... .. .. ... ..... 112 Power-sonic Corp .. ... .......... IBC RCS Radio .. ... ....... .... .. ........ 92 RF Devices .. ..... .. ...... ...... . 101 Rod Irving Electronics .. .. . 13 ,95 W)A ........ .. ... .. ...... .. ..... ....... 69 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 . THE HOMEBUILT DYNAMO by Alfred T. Forbes ISBN 0-9597743-0-4 Reviewed in S.C. October, 1988. $ABS including air mail post. (Brochure $AS refundable) Trade enquiries welcome. Todd-Forbes Publishing, PO Box 3919, ~::' Auckland 1, - '%! New Zealand. 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. PD/DE 1l1ff~~//III////II//II//////IIIII//////III// /IIII////////I/I//Q///ll//lll////lllli~111111'!!i s DNIC' 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