June 2000 - Silicon Chip Online

Outer Front Cover
Contents
Publisher's Letter: GST and price changes
Feature: Oooh, Aaaah! - Sony's New Digital Handycam by Ross Tester
Review: PC-Controlled Blood Pressure Monitor by Ross Tester
Project: Automatic Rain Gauge With Digital Readout by John Clarke
Project: Parallel Port VHF FM Receiver by Mark Roberts
Product Showcase
Order Form
Vintage Radio: A Japanese 110V AC/DC set by Rodney Champness
Project: Li'l Powerhouse Switchmode Power Supply; Pt.1 by Peter Smith & Leo Simpson
Project: CD Compressor For Cars Or The Home by John Clarke
Review: TiePie Handyprobe HP2 by Peter Smith
Book Store
Back Issues
Market Centre
Advertising Index
Outer Back Cover

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SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. The advertiser is no longer in business: www.optionalpower.com.au Contents Vol.13, No.6; June 2000 FEATURES 4 Oooh, Aaaah! – Sony’s New Digital Handycam Bored with new video products? Take a look at Sony’s new DCR-PC100E digital handycam. OOOOOH, AAAAAH!!! – by Ross Tester 8 Review: PC-Controlled Blood Pressure Monitor Measure and track your blood pressure for a healthy heart. The results are displayed on the computer screen – by Ross Tester 77 Review: TiePie Handyprobe HP2 Oooh Aaaah! Sony’s New Digital Handycam – Page 4. It’s a storage oscilloscope, a spectrum analyser, a voltmeter and a transient recorder . . . and it all fits in the palm of your hand. Whoops! – we forgot the PC; you need that as well – by Peter Smith PROJECTS TO BUILD 14 Automatic Rain Gauge With Digital Readout It collects, measures, records and empties. Best of all, you don’t have to leave the house– by John Clarke 26 Parallel Port VHF FM Receiver Use it to monitor the 144-148MHz amateur band, the 132-144MHz band, or the 118-132MHz band – by Mark Roberts Parallel Port VHF FM Receiver – Page 26. 56 Li’l PowerHouse Switchmode Power Supply This highly efficient design can deliver from 1.23V to 40V at currents up to 1.2A – by Peter Smith & Leo Simpson 62 CD Compressor For Cars Or The Home Do you have problems listening to CDs in your car? Are the soft bits too soft and the loud bits too loud? Here’s the solution – by John Clarke SPECIAL COLUMNS 38 Serviceman’s Log We’ve still got our jobs – by the TV Serviceman Li’l PowerHouse Switchmode Power Supply – Page 56. 53 Vintage Radio A Japanese 110V AC/DC set – by Rodney Champness DEPARTMENTS 2 33 34 37 Publisher’s Letter Product Showcase Subscriptions Form Electronics Showcase 43 90 94 96 Circuit Notebook Ask Silicon Chip Market Centre Advertising Index CD Compressor For Cars Or The Home – Page 62. JUNE 2000 1 PUBLISHER’S LETTER www.siliconchip.com.au Publisher & Editor-in-Chief Leo Simpson, B.Bus., FAICD Production Manager Greg Swain, B.Sc.(Hons.) Technical Staff John Clarke, B.E.(Elec.) Peter Smith Ross Tester Rick Walters Reader Services Ann Jenkinson Advertising Enquiries Rick Winkler Phone (02) 9979 5644 Fax (02) 9979 6503 Mobile: 0414 34 6669 Regular Contributors Brendan Akhurst Louis Challis Rodney Champness Garry Cratt, VK2YBX Julian Edgar, Dip.T.(Sec.), B.Ed Mike Sheriff, B.Sc, VK2YFK Philip Watson, MIREE, VK2ZPW Bob Young SILICON CHIP is published 12 times a year by Silicon Chip Publications Pty Ltd. ACN 003 205 490. ABN 49 003 205 490 All material copyright ©. No part of this publication may be reproduced without the written consent of the publisher. GST and price changes On July 1st, Australia will change its tax system to include GST on virtually all goods and services, with some exceptions for food and financial services. For SILICON CHIP this will have the direct consequence of a 10% rise in cover price. Despite Government publicity to the contrary, there will be no offsetting reductions in our costs since under the old tax system, newspapers, books and magazines were exempt from sales tax. I hope you will continue to support SILICON CHIP in spite of the price rise to come in July. My thanks to our subscribers who have already had to bear the GST increase. Indeed, because the GST was back-dated to December 1998, we have had a GST liability on any subscription taken out since that time which ran past July 2000 (ie, 2-year subscriptions). That was a bit of a shock to us since there was no way to allow for it. By the way, the July 2000 issue should go on sale late in June, so if you purchase it on or before the 30th June, you will avoid the GST for that issue at least (hint, hint!). As far as electronic equipment and other products are concerned, some will be reduced in price and some will rise. That’s another point the Government hasn’t been keen to talk about (perhaps they don’t know?). Whether or not a product’s price rises or falls depends on the retailer’s normal profit margin. If the margin is low, as in many consumer appliances, the price will probably drop a little, because the rate of GST is less than the rate of the old sales tax. But if the profit margin is higher, the retail price after GST is applied may well be higher. In fact, it seems to me that many retailers could legally add more than 10% to their prices, especially if they are for imported goods, because of the big fall in the Australian dollar over the last 12 months. Unfortunately though, some retailers and businesses will feel constrained against this and they may well suffer in the long run. I hope not. Printing: Hannanprint, Dubbo, NSW. It’s not all black though; many businesses will benefit from the introduction of GST since it will give rise to a GST credit on inputs. And all taxpayers will benefit to some extent from the reductions in income tax. Distribution: Network Distribution Company. On the face of it though, if there is a product you want to buy and you suspect it might be dearer after July 1st, buy it now. Subscription rates: $69.50 per year in Australia. For overseas rates, see the subscription page in this issue. Once again, I hope you will continue to support SILICON CHIP as we strive to maintain a big variety of projects and present them with as much detail as possible. Editorial & advertising offices: Unit 8, 101 Darley St, Mona Vale, NSW 2103. Postal address: PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 9979 5644. Fax (02) 9979 6503. E-mail: silchip<at>siliconchip.com.au ISSN 1030-2662 * Recommended and maximum price only. Leo Simpson PCI Plug & Play Printer / Serial Cards Available in 1, or 2 port versions, these PCI bus PnP bi-directional parallel ports have an 32 byte FIFO buffer. Support is provided for DOS, Win 95 & NT. Also available, are single, dual, 4 & 8 port PCI PnP serial cards. Cat. 2618 Cat. 2687 Cat. 2619 Cat. 2688 Cat. 2620 Cat. 2616 Cat. 2617 Cat. 2674 Cat. 2678 1 Port Printer PCI 1 Port Printer ECP/EPP/SPP PCI 2 Port Printer PCI 2 Port Printer ECP/EPP/SPP PCI Serial/Parallel 2S/1P PCI 1 Port RS232 16550 PCI 2 Port RS232 16550 PCI 4 Port RS232 16550 PCI 8 Port RS232 16550 PCI $79 $83 $119 $125 $119 $69 $99 $439 $669 USB Active Extension Cable Web-Based Training - Unlimited access to all courses in Group 1 from only $14.95 per month* New courses now available! Including Windows 98, Quicken 98, Lotus Notes, Internet Tools (Netscape) and more courses on TCP / IP. *Full details at www.tol.com.au Are you ready for GST? Point-of-Sale GST Bundle Omni-Directional Laser Scanner Our Point of Sale bundle includes a Citizen parallel printer (required by Digitill & Attache) or a Citizen serial printer (required by QuickPOS), a cash drawer and our very popular CCD bar code scanner. The cash drawer (Cat 8897) connects to, and is triggered from the printer, while the scanner (Cat 8196) connects between keyboard & computer. An affordable, vertically mounted, Omni-Directional laser scanner, which is ideally suited to reading bar coded products at supermarket checkouts. Depth of field is 300mm. Extend the distance between your PC & USB peripherals with a 4.8m long cable which includes an active Point-of-Sale GST Bundle - Digitill/Attache Cat. 8903 $869 amplifer to boost the signal level. It Point-of-Sale GST Bundle - QuickPOS Cat. 8902 $869 operates in accordance with USB Specification Ver 1.1 at 12Mb/Sec. Up to 5 cables POS Customer Display This POS customer display is driven from can connect in series for extensions to 24m. USB Active Extension Cable Cat. 9115 $74 the serial port and has a vacuum fluorescent display with two lines of 20 characVGA Monitor Splitters ters. It is ergonomically designed with a Splitter modules enable 270 degree viewing angle. Choice of up to 8 monitors to simul- 11.25mm or 9mm high character display. taneousy share the infor- Cat. 8728 POS Customer Display (Pictured) $379 mation of a host computer. Cat. 8907 POS Customer Display $339 The ideal way of providing multiple displays in POS Cash Drawers & Citizen Printers training rooms, airports, stock rooms, clubs, etc. Compact Citizen docket printTwo Output Cat. 3070 $269 Four Output Cat. 3055 $336 ers are ideally suited to compliEight Output Cat. 3056 $574 ment these POS cash drawers which feature robust metal Diagnostic Cards construction casing and a pearl white ABS fascia with a slip Just plug into a vacant PCI slot deposit slot. The bill tray has adjustable dividers for 4 or 5 and turn on the computer. A compartments along with spring loaded bill clips. A sepaLED display shows a numeric error code indicating the area of the fault. By rate coin tray has adjustable dividers for up to nine comchecking the error code against the appropriate partments. The printers feature 3 lines/sec, friction feed BIOS listing, the type of fault can be identified. The with 250 bytes input buffer, metal tear bar, 2 colour printing, errorcode messages for AMI BIOS, PHOENIX paper end sensor & automatic paper load. BIOS and AWARD BIOS are listed in the manual. Cat. 3422 Cat. 3128 Diagnostic Card - PCI Diagnostic Card - ISA $89 $69 Multi I/O ISA Card Now over 300 courses to choose from Cat. 8897 Cat. 8898 Cat. 5667 Cat. 5668 POS Cash Drawer -Epson/Star /Citizen POS Cash Drawer - RS232 Citizen IDP460 Parallel Printer Citizen ISP460 Serial Printer $195 $249 $420 $420 Compact Keyboard Cat. 8521 Cat. 8573 Magnetic Card Reader - KB Wedge A bi-directional magnetic stripe reader for credit authorization terminals, POS terminals, PC’s & banking terminals. Features easy keyboard wedge installation & requires no software modification, programming of I/O devices or additional power. Multi I/O Card $50 Cat. 8403 Compact 80 Key PS/2 $73 MCR - Track 2 KB Wedge MCR - Track 2 KB Wedge PS/2 MCR - Track 2 Serial MCR - Track 1 & 2 KB Wedge MCR - Track 1 & 2 Serial MCR - Track 2 & 3 KB Wedge Cat. 8045 Cat. 8681 Cat. 8418 Cat. 8417 Cat. 8203 Cat. 8218 $349 $399 $449 $439 $449 $439 Infra Red Keyboard with Point Button A handy compact sized 88 key keyboard with integral "mouse" pointing button. It is a cordless design using infra red technology. The receiver is fitted with a PS/2 Mini DIN connector. Cat. 8750 88 Key IR Keyboard with Point Button $129 20 Key Programmable Keypad Instant access to complex keyboard functions! This 20key auxiliary keyboard makes it easy to save multiple keystrokes or complex commands to a single keystroke. Clear keycaps that are easy to remove allow you to create, apply and reapply custom legends. A versatile interface card that supports 2 FDD, 2 When desk space is at a premium an 80 key keyboard with HDD,as well as 2 16550 compatible serial ports, 1 full 101 key functionality will come in handy. It has dimenCat. 8904 ECP/EPP printer port and 1 games port. sions of only 297(W) x 152(L) x 30(D) mm. Cat. 2055 Bar Code Laser Omni-Direct. KB Wedge $1599 Bar Code Laser Omni-Direct. Serial $1699 E & OE 20 Key Programmable Keypad $269 All prices include sales tax MICROGRAM 0600 Come and visit our online catalogue & shop at www.mgram.com.au Phone: (02) 4389 8444 Dealer Enquiries Welcome sales<at>mgram.com.au info<at>mgram.com.au Australia-Wide Express Courier (To 3kg) $10 FreeFax 1 800 625 777 We welcome Bankcard Mastercard VISA Unit 1, 14 Bon Mace Close, Berkeley Vale NSW 2261 Vamtest Pty Ltd trading as MicroGram Computers ACN 003 062 100 Fax: (02) 4389 8388 Web site: www.mgram.com.au FreeFax 1 800 625 777 Oooh, aaaah! One of the advantages of working at a major electronics magazine is that equipment suppliers (or their public relations people) want you to play with their latest and greatest products (in their eyes at least), in the hope that you’ll be impressed enough to feature them in the magazine. T he downside of that is we tend to become at least a little blasé, if not downright cynical, when it comes to a number of the products we look at. It’s difficult to get excited about a new widget when you’ve seen plenty of similar widgets before – and the new model is just another variation on a theme. It’s difficult to get excited about a new technology which they claim will set the world on fire when you know full well there’s another technology just about to be released which will blow it out of the water. It’s difficult to go “ooh, aah!” over a product regardless of the PR hype which tells us we should have! Enter the Sony DCR-PC100E digital handycam. OOOOOH, AAAAAH!!!!!! We first told you about this little beauty (and little is the operative, as you’ll see shortly) back in the “Products Showcase” section of the January 2000 issue (page 53). That was written sight unseen, purely from information supplied by Sony. Even so, it sounded pretty good to us at the time and Sony must have liked what we said because not very long ago, when stock became available, they asked us if we’d like to have a play with the real thing. That’s why, not six months later, this little Sony is getting another run. We’ve had our play and we’re impressed enough to give you our “hands on” impressions. First, some background for those who might not have seen the original article. The DCR-PC100E is claimed to be the world’s first digital camera which combines both video and still photography. Of course, there are many other digital video cameras around from which you can extract a single frame and call that a still photo – but that’s always a compromise in quality. Review by ROSS TESTER The Sony camera uses the mini DV cassette format for video and still photos and/or Sony’s own “memory stick” for still photos. The memory stick supplied with the review unit was only 4MB which was somewhat limiting – only six hi-res superfine pics would fit – but we still managed to give it the once (or twice) over. Memory sticks are available up to 64MB which would fit 96 hi-res (1152 x 864 pixels) superfine images or 300+ lower resolution photos. A 256MB version is scheduled for release next year. The memory stick itself is tiny – just 50mm long, 22mm wide and a couple of millimetres thick. It plugs into a slot in the back of the camera. Speaking of tiny, so is the camera itself: 127mm high, 123mm deep and only 61mm wide (or 125mm wide with the integral colour video screen wide open). The camera is a delight to use, due not in small part to its small size and weight (650g including battery and Sony DCR-PC100E 4 Silicon Chip These three shots of God’s own country (ie Narrabeen Beach) show the camera’s still photo “zoom” capabilities: the top pic is at full wide angle, the middle at full optical zoom and the bottom at full digital zoom. tape). It’s very nicely balanced when held against the eye and is not unwieldy to use at full arm’s stretch (for example, holding above the crowd to catch a scene in front). This is made very easy by virtue of the fact that the LCD screen rotates a full 270° and opens to a full 90°. Want to get in the picture yourself? Simply turn the LCD screen so it faces forward and use the self-timer! Or use the full-function remote control unit: it will start and stop the camera, capture individual pics, adjust the zoom (wide angle to tele-photo), allow searching and much more. We were going to make a comment about how “touchy” the zoom buttons were on the camera itself – going from full telephoto to full wide angle in about half a second. That was until we discovered (OK, we eventually read the instructions!) that the zoom control was actually variable – barely touching it gives an almost imperceptibly slow zoom; the more pressure that’s applied the faster the zoom. We had been using it as basically an on/off switch, which it isn’t! Having said that, it’s a bit touchy and does take a bit of getting used to. Digital Handycam JUNE 2000 5 Two modes of zoom are offered: optical and digital. An indicator in the viewfinder shows the level of zoom with a line marking the switch-over from optical to digital. Digital zoom is often poo-pooed by the purists as it is a “synthesised” image and usually results in a noisier picture. But the photo series demonstrates the capabilities of this camera. The lens, by the way, is a Carl Zeiss 4.2 to 42mm, which equates in standard 35mm camera parlance to a 48-480mm (or 40-400mm in memory stick mode). Minimum illumination is 7 lux (equivalent to f1.8) but an infrared lamp is built in, giving the camera the ability to shoot in total darkness – zero lux – in “Nightshoot” mode. This is a pretty nifty feature for anyone interested in wildlife photo-graphy or even surveillance work. We found the Nightshoot mode very effective up to about 5m away, especially when coupled with the camera’s “slow shutter” feature. The camera offers a variety of automatic exposure (AE) programs to make life really simple for you. Or you can do the whole thing manually – including focus and exposure. Some of the AE modes offered include spotlight (for minimising glare), soft portrait (so-called “anti wrinkle!”), sports lessons (minimis- The camera’s natural light and night shots are superb: above is a typical room-level light AND shot at low resolution; the one at right was at high resolution but was also completely handheld (ie, no tripod) and at full digital zoom. Try doing that with a conventional camera! 6 Silicon Chip es shaking), beach & ski (adjusts for strong light reflection), sunset & moon (for sunsets, night shots, fireworks, etc), landscape (stops the autofocus locking onto close objects) and low lux (where there is insufficient light level). And there’s also a host of special effects you can add including sepia finish, art and even black and white! Want to add titles? There are eight presets to choose from and you can have them in any colour. Or you can key in your own if you wish. Most functions are available to both video (tape) and still (tape/memory stick) recording. One feature worth mentioning is the use of the “InfoLITHIUM” battery. This special type of lithium-ion battery exchanges data with the camera to indicate state of charge and expected battery life. Video recorder We’re going to concentrate on the still photo capabilities in this review, mainly because digital video recorders have been around for a while. That’s not to say we weren’t impressed with the video side: it is superb, offering a wide range of standard and special effects and features. The DCR-PC100E uses mini-DV cassettes (standard DV, super-8 and other formats are not usable). It pops into a door in the back of the unit. For some functions, especially search operations, a special mini-DV tape with “cassette memory” is required. Still photos as well as moving action can be recorded on the tape with an amazing array of search features provided including photo search and photo scan, searching by date, title and memory zero. Video cassette recorder The camera can also double as an advanced VCR, accepting input from either standard composite video and stereo audio (eg, a suitably equipped television set) or from S-video. The latter is particularly important has it has become the standard for high quality home video recording. What's more, because recording to the DCR-PC100E is digital, you can edit (eg insert scenes from other sources) into your tapes without re-recording the tape. Audio dubbing is also a breeze and, unlike most ordinary VCRs, the original audio track can be left intact. You can even adjust the audio balance between old and new tracks via an inbuilt mixer. Similarly, titles can be recorded onto your tapes long after recording them. Stills photography As we mentioned, we were most interested in the Sony’s stills photography capabilities so the balance of this review will concentrate on that aspect. Apart from giving you a range of special effects and options simply not possible on a standard (still) camera, a digital camera has a huge but obvious advantage: you can see what you’ve shot there and then, and if you don’t like what you have you can do it again. No waiting for the film to be developed and printed and then finding out that the bride’s eyes were closed... You can review any or all of the images recorded on the tape or memory stick and throw out the shots you don’t want. Especially in the case of the memory stick, this obviously frees memory so you can record new images. This is all possible through a very intuitive menu system accessed via a push-button panel revealed when you open the LCD screen and also via a wheel which normally controls manual exposure level (if you want it). Images can be reviewed and retained or deleted one at a time, or if you’ve really messed things up you can bulk-erase the memory stick. Once erased, though, the images are gone for all time. You don’t have a negative to fall back on! Saving to computer The other big advantage a digital camera has is its ability to interface with a computer. You don’t have to scan in pictures – they’re already in digital (jpg) format, suitable for PC or Mac. The review unit came with a serial port interface and a CD-ROM containing “Picture Gear Lite” software. As its name suggests, the interface plugs into a spare serial port on your PC. The software allows some degree of picture processing but we used it simply to download the images we’d taken and then massage the pictures in our software of choice – Adobe Photoshop. There were a couple of wrinkles when we first tried to use the interface and software. Even though it says it is compatible with Windows NT, after we (apparently) successfully installed the software, try as we might we could not establish a connection between the interface and serial port. So we moved the whole shebang to another computer containing Windows 95 and... still no joy. This time, though it was a lack of a spare serial port (you really do need that mouse!). Third time lucky? Yes! We went to yet another machine which had a spare serial port AND ran Windows 95, loaded the software once again and voila! It found the interface unit first time. To really test our luck, we then decided to try it out on a brand new Pentium III machine running Windows 2000. There was no mention of 2000 compatibility on the software but it worked perfectly nevertheless. What you see on the PC screen after connecting the serial port adaptor through Picture Gear Lite. It gives some editing and manipulation capabilities. (Incidentally, we’ve since tried it on yet another NT4 machine and this time it worked perfectly. Hmmm...) Note that you cannot erase or delete images from the memory stick in the interface unit. That’s probably a safety feature so that you can’t accidentally erase your overseas trip while down-loading! We’re not sure if we were doing anything wrong but we couldn’t get the pictures to download at anything but 72dpi – fine for viewing on screen, using on the ’net and emailing to your friends – but not for publishing. The images were 420mm wide so we resampled them to 266dpi and 120mm wide – a bit naughty, perhaps but the results are there for you to see. We understand that Sony are going to (or perhaps now have) release(d) a Memory Stick adaptor which slots into your PC’s 3-1/2in disk drive. Now that would be handy... Picture size Because the images on the memory stick are recorded with JPG compression they’re quite small. A super fine image at 1152 x 864 will be around 600 kilobytes, while at the bottom end a standard image at 640 x 480 will be just 60KB. Needless to say, you can’t enlarge a 60KB image much but for web use or emailing, small is beautiful and even smaller is even more beautiful! As we previously mentioned, with the 4MB memory stick supplied we could fit only six 1152 x 864 superfine images. But if you’re prepared to accept the lowest resolution and quality (640 x 480, standard) you can fit a very respectable 60 images. If you really need to shoot a lot of hi-res, high quality images on memory stick be prepared for a lot of downloading – or buy a larger memory stick. A 64MB memory stick will set you back around $429. Price And that brings us to the price of the unit. As we said in the January issue, the Sony DCR-PC100E is not cheap (in any sense of the word). It’s going to cost you (at the moment) around $4600. With the bottom fallen out of the dollar recently and GST commencing just a few weeks after publication of this issue, what the unit will end up costing is anyone’s guess – up or down! But if we were looking for an extremely versatile video recorder with a still camera thrown in, we’d find it hard to go past this one. Overseas travellers would find it perfect – small size, all the tricks you want and stills pictures to email back home! We said at the start one of the advantages of working at SILICON CHIP was that we get to play with new toys. We forgot to mention the disadvantage: having to give them back! SC JUNE 2000 7 DynaPulse 200M A Shock to the System? A computer-based product recently submitted for review was responsible for a hastily arranged visit to the doctor. Product Review by ROSS TESTER The product in question was a blood pressure monitoring and tracking system, using a computer for both measurement/analysis and record storage. And the reason for the reality shock was a much-higher-than-expected series of readings. What happened was that once installed we dutifully measured all Silicon Chip staff and I was at least a little perturbed to find that my own blood pressure was significantly higher than everyone else's. Further reading con- vinced me to do something about it! Of course, most people would be familiar with the blood pressure meter used by doctors and nurses. Moe correctly known as a sphygmomanometer, it involves an inflatable armband "cuff" which is pressurised to restrict the flow of blood through the arm. Blood flowing through an artery makes characteristic sounds (known as Korotkoff sounds) and the physician listens for these with a stethoscope as the pressure is released. Left: the package includes the unit itself, arm cuff, inflator bulb, serial cable, software on floppy and user manual. 8 Silicon Chip This technique for measuring blood pressure is known as the ausculatory method. With each contraction or pump of the heart, blood pressure rises and falls. The highest blood pressure, as the heart contracts, is called the systolic pressure, while the lowest blood pressure is known as the diastolic pressure. When you hear a blood pressure referred to as "120 over 80", the first figure is the systolic and the second the diastolic. Below: the only control on the unit is the air release index dial. The DynaPulse 200M also measures pressure using a pressurised cuff and arterial pulsation but uses a slightly different method called Pulse Dynamics. This is claimed to be more accurate, agreeing extremely well with pressure-sensing catheter measurements which use a catheter actually inserted into the artery itself. Setting up The hardware consists of the pressure cuff, an inflating bulb with air release screw, connecting tubing and the DynaPulse 200M unit itself. Included is a 64-page instruction manual and software. Of course, you'll need a PC with Windows 95 and a free COM port. Hands up if you've ever read an instruction book all the way through before using anything? No, we didn't think so. We skimmed over the first couple of pages and thought "enough" – and then proceeded to install the software on a computer (from a single floppy disk) and the hardware, which plugs into a vacant COM port. Apart from the fact that we had to go out and buy four AAA batteries before it worked, everything installed and loaded perfectly. (There's a first time for everything...). Taking a reading This part is even easier! Instructions are basically menu driven, as shown in our screen shots. As many "patient" names are entered as required and then the appropriate person is selected from the list. The deflated cuff is slid up the arm to just above the elbow, tightened and held in place via Velcro fasteners, as shown on screen. The "air release index" is a dial on the DynaPulse unit Finally, you are presented with the results. Those shown are at the high end for a normal, healthy person. Anything higher is an indication of hypertension. I wasn't happy when my own readings were quite a bit higher . . . itself and 4 seems about right for most people. If it's not, it will tell you! Next screen tells you to close off the air release while you pump the bulb. When the cuff has enough pressure it will tell you to stop pumping and then you wait for between 15 and 45 seconds while the unit does its measurements. During this time the pressure on the scale drops with little "blips" in time with your heartbeat. Finally, the results screen appears showing systolic, diastolic and mean blood pressures, the heart rate and two histograms – one of the heartbeat cycle and the other showing the heartbeat cycles over the full measurement period. All this information can be saved in the person's file and printed out if required. If used over a period of weeks, months or years a "trend" graph can also be produced – very handy if your physician has you on medication to lower blood pressure. The software can plot a blood pressure and heart rate trend graph. Red trace is systolic, blue is diastolic and yellow is average blood pressure. You can see at a glance if it is working! Conclusion With heart disease the biggest killer in the western world (and Australia is right up there with the worst of them), having accurate, reliable blood pressure data could be the difference between a life and death situation. It's certainly jolted me into action. I know I'm overweight – 20kg, less would be lovely! But I've basically been healthy and don't smoke and drink very little. So high blood pressure has never been top-of-mind for me. Now it is! High blood pressure, or hypertension, is believed to be a major factor in strokes, heart attacks and heart disease. It also means your heart has to work that much harder to circulate the blood around your body. There is no doubt the DynaPulse 200M does its job very well. It's easy to set up, easy to use and having the computer records available for your doctor could be very beneficial. At an RRP of $369 (pre-GST), some might think it expensive. But how SC much is your life worth? Where do you get it? The DynaPulse 200M is available from Microgram Computers, Unit 1, 14 Bon Mace Close, Berkeley Vale NSW 2261. Phone (02) 4389 8444; Fax (02) 4389 8388; website www.mgram.com.au JUNE 2000 9 SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.dse.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.dse.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.dse.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.dse.com.au Once upon a time, rain gauges were as much a part of the Aussie backyard as the outhouse. Both started disappearing about the same time – possibly because both required periodic manual emptying! Here’s a PIC-powered, fully automatic rain gauge that reads the rainfall, empties itself, stores the reading and remembers up to two months of data – without you leaving the comfort of your home. By JOHN CLARKE PIC-Powered Rain Gauge Features * Self-clearing rain sensor. * Remote monitoring. * Rainfall shown on a 3-digit display. * Max. reading of 254mm (10") per day. * Stores 61 days of rainfall data. * Settable end of day empty time. * Hold feature to prevent incorrect readings when cleaning sensor. * Reset facility to clear previous readings. * Valid data indication for previous days readings. * Battery backup for operation in a blackout. * Tamper-proof against setting changes. 14 Silicon Chip T his fully automatic rain gauge does not require emptying and will store 61 days of rainfall readings. Rainfall is shown on a 3-digit LED display and you can monitor this without going outside. A traditional rain gauge consists of a container with a measurement scale down the side wall. The idea is that the rain gauge is mounted on a post right away from the influences of buildings (fence posts were typically used but paling fences alter wind patterns too much). Rain falls, a certain amount enters the container, it starts to fill and you read the result off the scale in either millimetres or inches and points. Those old enough to remember inches and points will also remember that there are 100 points to the inch – sort of a pre-decimal decimal, if you like. A point of rain isn’t much – just a short shower, really, while an inch of rain is usually several hours of steady rain. (Sydney’s annual rainfall is about fifty inches or so; the recent outback floods were reported to result from 8-10 inches in a couple of days). These days we use millimetres and, of course, there are 25.4mm to the inch. However, we digress: back to our old-fashioned rain gauge. While accurate and reliable, it suffers from the disadvantage of requiring emptying on a daily basis and manual recording of the rainfall if you want a record. A better mousetrap rain gauge? A more useful rain gauge would be one which did not require the constant daily maintenance and which could be monitored remotely. Also it would be ideal if the rain gauge could log, or remember, previous days rainfall up to several weeks in the past. This would allow the unit to be left unattended for extended periods without loss of the rainfall information. The SILICON CHIP Rain Gauge has these features and more. Ours uses a microcontroller to not only record the rainfall each day but to remember it. The rain sensor mechanism itself is housed in a short length of 90mm PVC stormwater pipe. The rainfall measurement from this is brought via suitably long wiring to the display unit which is housed in a small plastic case. The display unit comprises a 3-digit display for the readings and a row of rectangular LEDs to indicate the current display function or mode. Three pushbutton switches access the many features of the rain gauge unit. It is powered from a DC plugpack and has a battery backup to ensure operation in a blackout. The normal setting of the rain gauge displays the current day’s rainfall and this is indicated by the “Rainfall Today” LED. This reading is updated as more rain falls. You can access the previous day’s rainfall by pressing the Down switch. This will now be indicated by the “Previous Days” LED and the 3-digit display will alternate between showing the day selected and the current day’s rainfall. The display switches at a 0.78s rate giving you sufficient time to read the values. The next previous day will be shown at the second pressing of the Down switch and up to 60 days past can be selected. The Up switch provides the means to return to the “Rainfall Today” display. Indication of the previous days is referenced to the current day (today) so that a -1 on the display means the day before today (ie, yesterday). Similarly a -2 means two days before today. The -60 indication is therefore 60 days before today. It provides us with a total of 61 days of rainfall information. This rain gauge would have been useful for Noah. He would have been able to keep a record of the forty days and forty nights rainfall during the flood, all while he was sitting back watching videos and surfing the ’net The “works” end of the Rain Gauge shown in cutaway format. Rain enters through the mesh at top and is funnelled (literally) into the pivoted container. When the weight of the water in the container is high enough it flops over and a tongue attached to the container interrupts a phototransistor circuit, registering a pulse. The opposite half of the container then starts to fill in the same manner. The emptied rain then drains away through the bottom of the unit. inside the ark. OK, that’s a fib: all the video stores were flooded out! At the end of each day, the “today’s rainfall” tally is transferred to the previous day’s log (today -1) and the same goes for the rainfall information for all the other days past. For example the today -1 rainfall is transferred to today -2 with the today -2 information transferred to today -3. The today -60 information is lost since the today -59 rainfall tally is JUNE 2000 15 Fig.1 (left): the PIC microcontroller does all the work in the Rain Gauge. It accepts input pulses from sensor 1, processes the information and drives the LED displays. moved into that day’s location. Note that during the first 61 days of use, past days rainfall information may not be correct since the rainfall may not have been recorded for that day. In fact, when you first install 16 Silicon Chip the Rain Gauge, all the previous days readings from today -1 up to today -60 will not have been logged. After each day the next previous day’s readings will become valid as they are transferred to that day’s log. The Rain Gauge includes an “Invalid Data” LED indicator to circumvent any confusion over which data has been recorded and which data has not been counted by the rain gauge. The Rain Gauge includes a clock and an empty time setting facility. The clock is set at the current time and the empty time setting is selected for when you want the day’s reading to be stored. For example, if you would normally check a traditional rain gauge at say 7am then you can set the empty time to this. Alternatively, you can set the empty time to midnight so that a true daily reading is obtained. Or you could choose any other time. The rainfall will be counted over a 24-hour period, starting and finishing at the empty time. The empty time represents the start and finish of the day, so far as the rain gauge is concerned. The clock and the empty time are 24 hour types and only show the hours and tens of minutes. Thus the time and empty time can only be set in 10 minute increments. The display will show 033 for 3:30am, 120 for 12:00 (midday) and 121 for 12:10. Midnight is indicated as 240 for 24:00. The clock and empty time are set by pressing the Mode switch to select the required function, while the up and down switches are used to set the time. The indicator LEDs for “Set Time” and for “Set Empty Time” show which particular display is selected. The Mode switch also selects the Hold/Reset function. This is indicated by the associated Hold/Reset LED. With this selection any rainfall detected by the rain sensor will not be counted. This feature is useful for when the rain gauge sensor is being cleaned or if a sprinkler is placed near the sensor, causing false rainfall detection, or for any other reason. A Reset can be made when the Up switch is pressed and the Hold/Reset function is selected. The reset clears the current days rainfall tally and resets the “invalid data” indicator function so that it shows for previous days starting from today -1. Previous days’ rainfall values are not cleared Fig.2: follow this diagram when building the PC board. You could substitute burglar alarm or other cable for the link between the main unit and the remote sensor. The wiring to the DC socket suits positive-tocentre plugpacks. Reverse this wiring if your plugpack is negative-to-centre. but only indicated as invalid. You will need to reset the rain gauge after it has been fully tested and before commissioning it in use. The setting functions are tamper-proof meaning that it is not possible to change them unless the Mode switch is pressed, which can only be done using a small probe inserted into the case. The design has been optimised to make sure that rainfall data is not lost easily. As mentioned before, the rain gauge has battery backup so that it keeps operating in a blackout. However, if the battery backup is not used or the batteries go flat, the most data you can lose is the blackout time plus up to 10 minutes depending on when the blackout occurs. This is because the current time, the empty time, today’s rainfall and the previous days’ rainfall are stored in a permanent memory which is not lost on power down. The time and today’s rainfall count are updated into this type of memory every 10 minutes while the previous days’ data and the invalid data counter are updated at the empty time. 3 are tied together. The LEDs within DISP4 are tied to the “b”, “a”, “f”, “g”, “e” and “d” segments respectively To drive one of these displays one of the RA0, RA1, RA2 or RA3 lines is brought low. If RA0 is brought low, for example, transistor Q4 will be switched on and allow power to the common anode connection of the LEDs in DISP4. Any low outputs on RB1-RB7 will light the corresponding LED in the display, DISP4. After this display is lit for a short time, the RA0 output is taken high and the RA2 line is brought low to drive Q1 and display DISP1. The new 7-segment data on the RB1-RB7 outputs is presented to this display. Similarly, the RA3 and RA1 lines are brought low to drive DISP2 and DISP3 respectively. The Mode, Down and Up switches (S1, S2 & S3) are monitored at the RA4 input. These switches also connect to the RA2, RA1 & RA3 outputs respectively. Normally the RA4 input is held high via the 10kΩ resistor connecting to the 5V supply. When a switch is closed, it will pull the RA4 input low. IC1 can test which switch is closed by knowing that if RA4 is low when RA2 is low then it is the Mode switch that is closed. A closed Down switch will show a low on RA4 when RA1 is low and a closed Up switch will Circuit details Fig.1 shows the Rain Gauge circuit. IC1 is the microcontroller which forms the basis of the circuit with the displays, switches and rain sensor input attached to it. The LED displays, DISP1-DISP4, are driven directly from the RB1-RB7 outputs of IC1 via 150Ω limiting resistors. All of the segments on DISP1, 2 and The completed PC board sitting inside its case. Note that the vertical PC board guides have been filed away to a depth of 13mm from the top – this allows the board to sit in position without screws. The four tapped spacers stop the board from moving when the lid is in place. JUNE 2000 17 Parts List For Rain Gauge 1 PC board, code 04105001,107 x 62mm 1 Rain Gauge front panel label, 124.5 x 62mm 1 plastic case, 130 x 67 x 44mm 1 3mm transparent red Perspex or Acrylic sheet, 56 x 18mm 2 AA cells (alkaline or NiCd/NiMH) 1 2 x AA cell holder 1 DC panel socket 1 9V DC 300mA plugpack 1 SPST tactile switch (S1) (Jaycar Cat. SP-0730 or equiv.) 2 PC-mount snap-action keyboard switches (S2,S3) 1 3.2768MHz parallel resonant crystal (X1) 1 18-pin DIL socket 4 M3 x 9mm tapped brass standoffs 5 M3 x 6mm screws 1 M3 nut 1 small rubber grommet 7 PC stakes 1 100mm length of 0.8mm tinned copper wire 2 50mm lengths of medium duty hookup wire 1 10m length of 3-way (or 4-way) cable Semiconductors 1 PIC16F84P microcontroller programmed with RAINA.HEX* (IC1) 3 LTS542A 7-segment common anode LED displays (DISP1-DISP3) 1 DIL 10-LED (red) bargraph (DISP4) (Jaycar Cat. ZD-1704 or equiv.) 1 photo-interrupter (sensor 1) (Jaycar Cat. Z-1901 or equiv.) 1 7805 5V 1 A regulator (REG1) 4 1N4004 1A diodes (D1-D4) 4 BC328 PNP transistors (Q1-Q4) Capacitors 1 100µF 16VW PC electrolytic 2 10µF 16VW PC electrolytic 2 0.1µF MKT polyester 2 15pF NP0 ceramic Resistors (0.25W, 1%) 1 100kΩ 1 10kΩ 1 1kΩ 4 680Ω 1 220Ω 7 150Ω Mechanicals The rain detector unit itself is relatively simple to make up – follow the photographs and the drawings and you should have no problems. Most of the mechanical parts are made by cutting up a standard (83 x 54 x 31mm) jiffy box and using offcuts from a 90mm stormwater pipe and end caps. The rain water enters the unit via a funnel which directs it into a divided water container mounted on a pivot. When one side of the container fills, the weight of the water causes it to tip, emptying its water load in the process. The other side now fills and tips the container back again. A lug attached to the container passes through a photo interrupter every time the unit tips and this is recorded as 1mm of rain. The unit is calibrated with a simple screw adjustment to set the water container tip angle. The entire assembly is housed inside 90mm stormwater pipe with drilled-out end caps on each end. The ends are covered in flyscreen wire to prevent spiders entering and fouling the mechanism with their webs. Rain sensor * If you wish to program your own PIC, raina.hex and raina.asm are available to download from the SILICON CHIP website, www.siliconchip.com.au Parts For The Rain Sensor 1 180mm length of 90mm PVC stormwater pipe 2 90mm UPVC endcaps 1 plastic jiffy box, 83 x 54 x 31mm 4 M3 x 25mm brass screws 2 M3 x 25mm Nylon screws 2 M3 x 12mm Nylon screws 4 M3 x 6mm brass screws 12 M3 brass screws 10 M3 Nylon or brass washers 4 untapped 4BA brass spacers, 6mm long 1 plastic funnel, 86mm diameter (or 90 x 180mm galvanised sheet and 12.5mm diameter x 15mm copper tubing) 2 90mm diameter aluminium or brass flyscreen wire 1 small rubber grommet 1 100mm long cable tie 1 neutral cure Silicone sealant (roof and gutter type) 1 tube super glue 18 Silicon Chip show a low on RA4 when RA3 is low. The rain sensor (sensor 1) consists of an infrared LED and phototransistor housed in the one package. There is a slot in the package to allow a vane to pass and block the light beam to the phototransistor. Normally, the vane is out of the slot and the light from the LED passes to the phototransistor, switching it on. This means that the voltage at IC1’s RB0 input is low. As the weight of water causes the container to flip over, the vane enters the slot and the light is blocked. This turns the phototransistor off and the RB0 input goes high via the 100kΩ pullup resistor. The 0.1µF capacitor suppresses noise on this input. The transition from a low to a high is acknowledged by IC1 as a count from the sensor. The vane quickly leaves the slot as the container continues to flip over, allowing the light from the LED to turn the phototransistor back on again and pulling the RB0 input low once again. It stays in this state until the container is once again flipped over. Crystal X1 provides the oscillator component for IC1 which runs at 3.2768MHz. This frequency is divided down four times by the microprocessor for its internal operation. Another internal counter further divides this by 512, resulting in a frequency of 1600Hz which multiplexes the displays. Further division provides us with a pulse once every ten minutes which updates the system clock. Power Power for the circuit is derived from a 9V DC plugpack which supplies the 5V regulator REG1 via a reverse-polarity protection diode D1. The 100µF capacitor at the input to REG1 decouples the supply, while the 10µF capacitor at the output provides protection against oscillation of the regulator. The normal regulator output of 5V is increased by about 0.6V due to diode D2 between the regulator’s ground terminal and ground. This increase in voltage at REG1’s output is brought back down again by diode D3. This diode isolates the regulator output from the 3V battery supply, while yet another diode (D4) isolates the 5V supply from the 3V battery. If the regulator is powered, D3 conducts and supplies power to IC1. Diode D4 will be reverse biased due to the higher voltage on its cathode compared to its anode and so the 3V battery will not supply current. If you wish to use rechargeable batteries (2 x NiCd or NiMH giving 2.4V), the 220Ω resistor can be used to provide a trickle charging current. If power to the plugpack fails due to a blackout, D4 will be forward biased and the 3V battery supplies IC1 with standby power. Construction We’ll start the construction with the electronic section of the Rain Gauge. This is built onto a PC board coded 04105001 and housed in a plastic The front panel (above) can be photocopied and used as is and/or used as a drilling template for the top of the case. Use the PC board pattern (below) to check commercial boards or to photographically make your own board. case measuring 130 x 67 x 44mm. A front-panel label is glued to the lid of the case and the LED displays are visible through a transparent red Perspex or Acrylic window in the case lid. Begin construction by checking the PC board for shorts between tracks or any breaks in the copper connections. Compare the PC pattern with the published artwork to be sure it is correct. Now check the hole sizes. The corner mounting holes and regulator tab mounting hole should be 3mm in diameter. The PC stakes should be a Resistor Colour Codes No. Value  1 100kΩ  1 10kΩ  1 1kΩ  4 680Ω  1 220Ω  7 150Ω 4-Band Code (1%) brown black yellow brown brown black orange brown brown black red brown blue grey brown brown red red brown brown brown green brown brown 5-Band Code (1%) brown black black orange brown brown black black red brown brown black black brown brown blue grey black black brown red red black black brown brown green black black brown tight fit into their respective holes. Install the PC stakes first, followed by the resistors. Use the resistor colour code table as a guide to their value. Alternatively use a digital multimeter to measure each one. Note that the 220Ω resistor should only be installed if you intend to use rechargeable cells for the battery backup. Insert and solder in the diodes next, making sure that they are oriented correctly. The 7-segment LED displays must be installed with the decimal point on DISP1-DISP3 facing toward the switches. DISP4 should be installed with the label side towards IC1. You can now install the IC socket with its pin 1 oriented as shown. Don’t install the microcontroller just yet. Capacitor Codes Value IEC Code EIA Code 0.1µF 100n 104 15pF 15pF 15 JUNE 2000 19 The capacitors can go in next, using the capacitor code table as a guide to their values. The electrolytic types, which are positioned on their sides as shown in the photographs, must be oriented correctly, with the positive lead placed as shown on the wiring diagram. Similarly, the crystal is placed on its side and is secured at its free end using a short length of tinned copper wire soldered to the PC board and crystal body. CI 20 Silicon Chip A D Now install the PC stakes at the external wiring points. The switches can then go in, taking care to ensure that the flat sides of S2 and S3 are oriented as shown. S1 must be installed so that the leads are oriented as shown. This switch should normally be an open circuit between the bottom and top pins. Transistors Q1-Q4 can be inserted with their height level with the top of the displays. REG1 is mounted Fig.3: these drawings, in conjunction with the photographs, show how the various components are fashioned from a “Jiffy” box. Start with the box (without lid) and carefully make three cuts with a hacksaw where shown. Most of piece “A” becomes the water container itself while that end of the box (“C”) becomes the vane which triggers the photo transistor. The pillars and guides which need to be removed can be either broken off and filed neat or, if you are particularly careful, melted away with a soldering iron and then filed neat. Note that on the “A” piece, only one set of guides and one pair of pillars are removed – the rest are used! Similarly, on the support stands (“B” pieces), one pillar portion remains – this forms the support for the bearing shaft through which the water container pivots on Nylon screws inside untapped spacers. horizontally with the leads bent down 90° so they can be inserted into their respective holes. The tab is secured with a small M3 screw and nut. The corner mounting holes are used to mount the 9mm tapped standoffs above the PC board and are secured with M3 screws. The PC board is mounted in the case by cutting the integral guides on either side of the case so that their top edges are 13mm from the top. This will allow the PC A C BII E Fig.4: the Jiffy box lid is not wasted – most of it (“D”) becomes the vertical divider between the two halves of the water-measuring container (shown below glued in place with the two adjustment screws in position). One of the two offcuts (“E”) becomes the mount for the LED/ phototransistor assembly. board to slide into the case and be held in place by the standoffs when the lid is attached (see photograph). Drill a hole in the end of the case for the rubber grommet required for the rain sensor lead and at the other end for the DC socket. The leads from the PC board to the DC socket, the battery holder and to the rain sensor can now be run as shown in Fig.2. We used three wires from a length of 4-wire telephone cable for the connection between the sensor unit and the electronics. Other suitable cable would be alarm cable or twin conductor shielded cable with the shield being used for the earth connection. Use the front panel artwork as a guide to drilling the holes for the switches and display cutout. This cutout is drilled and filed so that the red Perspex or Acrylic window is a tight fit. A tiny drop of super glue may help hold it in place if it is not a tight fit. Attach the front panel label and cut out the holes in this with a sharp knife. Figs.5a & 5b: how the various pieces go together to make the tipping bucket. These two drawings show the same assembly – the top view shows the assembly side-on, while the bottom drawing is a sectional view (ie, rotated 90°). Testing Connect the DC plugpack and test that there is a nominal 5V supply between pins 5 and 14 of IC1’s socket. If the voltage is between 4.5V and 5.5V, the plugpack can be removed and IC1 installed. Apply power again and check that the display lights and shows 0 with the Rainfall Today LED lit. Press the Down switch and you should obtain a display which alternates between a -1 and a 1. The -1 refers to the day selected and the 1 is the initial preset rainfall data. The Previous Days LED should now be alight as well as the “Invalid Data” LED. Pressing the Down switch again will have the display show a -2 and a 2. Press the switch repeatedly to check that you can access all the previous 60 days (-60). Each day should have rainfall data equal to the selected day: day -59, for JUNE 2000 21 BII D A A BI C BII E LED/Phototransistor Assembly 90mm Pipe Cap Here’s how the completed bucket/sensor assembly should look. Again, we have labelled the various components to agree with Figs.3 & 4 to make life easy. Note how the vane (C) swings through the LED/phototransistor without any restriction. example, will have rainfall data of 59. Now press the Mode switch and select the Set Time function as indicated by its associated LED. It should show 120 for 12:00 midday. It may show a later time if you have left the rain gauge on for more than 10 minutes. Press the Mode switch and the Set Empty LED should light and the display will show 240 for 24:00 midnight. Adjust this time with the down switch so that it shows the same time as the Set Time display. Now press the Mode switch once to obtain the Hold/ Reset LED and “- - r” display and press it again to obtain the Rainfall Today display. Now press the Down switch and the -1 day should now have 0 as its rainfall. The “Invalid Data” LED will not be lit. The -2 day should have a 1 for its rainfall. The “Invalid Data” will show for this and remaining days. Each other previous day should have a rainfall that is a value one less than the day’s absolute value. For example, the 22 Silicon Chip -60 day should have 59 as its rainfall. This demonstrates the end of day transfer of data from one day to the previous day. The input counter can be checked by momentarily contacting the GND (E and K connections of sensor 1) to the collector terminal (C for sensor 1). The Rainfall Today display should show 1, then 2, etc for each contact, incrementing from 0 to 254. The next count will be three dashes, indicating overrange. You can clear this data by returning to the Hold/Reset mode and then pressing the Up switch to reset. The display will show “rES” indicating that it has reset. Returning to the Rainfall Today Mode will show a 0 in the display. Return to the Hold/Reset mode and trigger the counter as before. Return to the Rainfall Today selection to check that the rainfall display is still at 0. The Hold feature therefore prevents any rainfall counting. When setting the time, the 10 minute counter is reset whenever the Up or BI D E Another view of the complete assembly looking almost straight down. The double-sided water container is perfectly balanced, brought that way by adjusting the screws at the top in and out as required. Down switch is pressed. This means that the time begins from the time set and it will be a full 10-minutes before the time increments. So to obtain the correct time you must press the switch at the time when your reference clock shows a 10-increment. In practice, this means that the time should be set when the minutes on the clock you are setting it against changes from either a 9 to a 10; eg 19 to 20, 39 to 40, etc. This does not apply to setting the empty time which can be set without regard for the current time. The current time is compared with this empty time and when they are equal, the microcontroller moves the daily rainfall data along by one day. Rain detector As mentioned, many of the parts for the rain detector are made from parts cut from a plastic case measuring 83 x 54 x 31mm. Part of the base of the case is used as the water container, with the lid providing the divider between the two sides. An end of the case is used to make a vane for the sensor 1 detector, while the other end of the case makes up two support stands for the water container pivot. One end of the lid makes a mounting plate for the photodetector (sensor 1). Fig.3 and Fig.4 show how the parts are cut from the lid and base of the case. The base is cut so that some of the integral slots in the side become the centre of the water container. The end marked (C) is cut off as shown and the pillars removed on the water container section. File the sawn edges Rain enters the top of the 90mm pipe via a protective insect screen. This is thin enough to be gripped by the cap, shown removed here. You can make your own funnel, as we did, or simply cut the top off a small funnel so it forms a tight fit in the pipe. Secure it in place with silicone sealant. to a smooth finish. The support stands are made by cutting the (B) side of the box into the sizes shown. Remove one of the pillars from each support stand (B’ and B’’). The vane (C’) can be cut to shape as shown. Cut the lid to size and remove the small flanges on the divider section (D). The section marked (E) is to mount Sensor 1. You will need to file the two edges of the divider (D) to 50mm wide so that it slides neatly into the side slots of the water container. We rounded the bottom section of the divider so that the base of the container will be curved slightly. This is not strictly necessary and can be left straight. The divider is glued into the water container with super glue. To do this, first slide the divider in place and run the glue around the edges to secure it. The glue sets very fast on this plastic so do not run glue in place before inserting the divider or the slots will become clogged with set glue. The vane is glued to the underside of the water container central to and at right angles to the divider. Draw a pencil line down the centre of the underside of the container to mark the position for the vane. Now run some super glue along the 45mm long edge of the vane and attach it to the container in position. Hold it in position until the glue sets. The pivots for the water container need to be 12mm down from the sides as shown in Fig.5 and in the centre of the divider. Drill holes so that the 6mm long spacers insert as a tight fit with about 0.5mm of spacer protruding at each side of the water container. You will need to seal the edges of the divider and ends of the spacers inside the water container with a smear of silicone sealant to prevent water from escaping. The photodetector, sensor 1, can be mounted onto the (E) mounting plate using two Nylon screws and brass nuts. The sensor is mounted central to the mounting plate. Secure this mounting plate in the centre of a 90mm stormwater end cap using brass screws and nuts. Drill mounting holes in the support stands B’ and B” as shown in Fig.3. Drill out the pillars so that the M3 Nylon screws will form a shallow thread when screwed in place. Mount the support stands 69mm apart along the same centre line as the sensor 1 mounting plate using brass screws and nuts. Screw in the Nylon screws through the pillars in the support stands and cut them to protrude by 5mm from the inside edge of the support stands. Drill holes for the M3 x 25mm screws on the top of the divider. These are best drilled slightly undersize so that the screw will cut a thread in the hole. Place the 6mm spacers in position as shown using nuts to hold Fig.6: here’s how we fashioned the funnel from a small piece of thin galvanised iron. Alternatively, you could use a suitable plastic funnel and cut the top off so it measured 86mm across. Similar to the top, the bottom is protected against spiders and other insects by a screen. Make sure the holes are big enough to allow the water to drain away immediately. them in place. The second screw does not have the spacers. Assemble the unit with the water container pivoting on the Nylon screws by gently prising the support stands outward to allow the screws to be inserted into the water container’s bushings. Check that the vane passes through the sensor slot without fouling. You may need to trim this piece for best clearance. Note how many washers you will need on each side of the pivots so that the vane swings through the centre of sensor 1’s gap. Install these in place. Adjust the top screws on the divider so that the tendency of the water container to fall to either side from upright is not biased in one direction or the other. Mark out where the end stop screws need to be installed in the end cap so that the top of the screw end will catch the underside of the water container for each side. Note that these screws will need to be offset from centre to prevent fouling the vane. Drill the holes for these end stop screws slightly undersize so that the thread will be cut into the plastic. This will allow easier adjustment. The nuts are simply used to lock the screw in place after the adjustment is set. Also drill holes for the rubber grommet for the wire entry and large holes to allow the water to flow out. Cut the 90mm-diameter stormwater pipe 180mm long and cut out the inside of one of the end caps so that it has an 86mm diameter hole. The 86mm diameter is important in the JUNE 2000 23 calibration process – it must be peramount of water. because of the water inertia rather fectly round and it must be exactly How do you get exactly 5.8ml of than its weight. The calibration can 86mm. be checked by counting the number water? By far the easiest way is to use This endcap becomes a cover to a 10ml syringe (hypodermic) without of tilts. hold on the wire mesh over the end the needle, of course. Your local pharFor example, one litre (1000ml) of of the pipe. macist or doctor might be able to give water should tip the water container you one once he or she has disposed 172 times (1000/5.8 = 172). It is probA funnel can be modified by cutably easier to wire up the sensor to the ting a slightly larger plastic funnel to of the pointy bit in their sharps bin. circuit and attach the 90mm pipe and 86mm outside diameter or you can These syringes are graduated to fashion your own using galvanised 0.1ml so you can get the right amount funnel assembly, so that the number iron sheet and a 15mm length of easily – and it’s easy to put the water of tilts can be counted on the display. 12.5mm copper pipe. It is folded so the exactly where you want it, too. After wiring the sensor you will two straight edges are placed together need to cover the connections with Adjust the end stop screws so and the 5mm flange is soldered to the silicone sealant. This will prevent that the water tips both sides of the back of the funnel. The copper tubing container with the 5.8ml quantity of corrosion and also prevent the water is soldered to make an outlet at the water. Screw the end stops higher making contact between collector funnel base. and emitter of the detector transis(clockwise) so that the amount of tilt Overall height is about 85mm. The is less if you need more than the 5.8ml tor, which may prevent the sensor outlet from a plastic funnel may need of water to tip it. Screw the end stop from detecting the swing of the vane to be cut shorter to prevent it catching screws anticlockwise to lower the reliably. the divider. endstops if you require less than the Secure the end stop screws with 5.8ml of water to tip. the lock nuts and insert the 90mm The funnel is secured inside the diameter flyscreen inside the bottom tube with some silicone sealant apThe top weights on the divider will plied around the inside top edge of need to be changed if you cannot ob- end cap. Secure with some dobs of the funnel and pipe. Place the 90mm tain an adjustment with the end stops silicone sealant. diameter flyscreen on top of the pipe that calibrates the tipping correctly. Installation and place the opened end cap in position. Wait for the The rain gauge sensor can sealant to cure. be supported using standard 90mm downpipe fittings or Current consumption: 30-60mA with a 12V DC input, Calibration even with heavy-duty cable 3mA when powered by 3V battery. ties or galvanised wire and First of all, we need to 2 2 Rain gauge collection area: 5808mm (or 5.8cm ). attached to a free standing determine how much water Volume collected per mm of rain: 5.80884ml (cc). post or one protruding above (ie, rain!) entering the gauge a fence. represents 1mm. You will Measurement resolution: 1mm. recall we said it was imporIt will need to be located Rainfall accuracy: Depends on calibration adjustment tant to get the end-cap cutout away from trees and similar (can be set to within 1% plus 1 digit). exactly an 86mm dia meter rain obstructions for the best Clock accuracy: ±10.5 minutes per year unadjusted. circle. This is the figure we accuracy. It should also be use to calibrate the gauge. several metres away from walls and solid fences to Rainfall is measured in If the water container tips too early prevent it from being in a rain shadow millimetres which simply means the depth of the rain which gathers (ie, before the full quantity of water or even a rain funnel. has been poured), then the weights in a specific area where there is no The clock accuracy depends on are not sufficient and you will need run-off or no run-in. To work out the the actual crystal frequency. These rainfall, all you need to know is the to add more weight. have a tolerance of ±20ppm which Try adding two more 6mm spacers area. Our area is of course an 86mm means that the clock could be some on the second screw and secure with 10 minutes fast or slow at the end of diameter circle. two nuts in the same way as the first one year. This should be adequate The area of a circle is represented screw. If the amount of water required for the rain gauge, however, it could by π times the radius squared (πr2). be readjusted each year if necessary. The radius is, of course, half the dia to tip the water container is more than the 5.8ml, you will need to reduce meter so that is 43mm. Therefore the Alternatively you can use a 22pF collection area is πr2 or 3.14159 x the weight. trimmer capacitor in place of the Try removing both of the 6mm 432 = 5808 square mm. For 1mm of 15pF fixed capacitor between pin 16 spacers. Make sure that you use the of IC1 and ground. The crystal can rain, the volume is 5808 cubic mm same weight on either side of the di- then be trimmed to 3.2768MHz using or 5.8ml. vider to maintain the balance of the a frequency meter or by trial and error You can initially calibrate the rain tilting action. testing over a period of time. sensor by slowly pouring in 5.8ml Best calibration results can now be (or cc) of water directly into one side Note that a probe on the oscillator obtained by again slowly pouring in of the water container without the pins will affect the crystal frequency a large quantity of water. Note that – it is best to place a low capacitance 90mm pipe and funnel installed over if you pour the water in too fast you (10:1) probe on pin 15 (OSC2 input) the unit. Check that each side of the SC water container tips at exactly this will cause the water container to tilt for least frequency change. • • • • • • 24 Silicon Chip Specifications Address http://www.oatleyelectronics.com Ph ( 02 ) 9584 3563 or 9584 3564 PO Box 89 Oatley NSW 2223 Fax 9584 3561 e-mail orders: sales<at>oatleyelectronics.com 1st FOR AUSTRALIAN MADE KITS DEVELOPED IN AUSTRALIA!!! 650nm VISIBLE LASER DIODE MODULE: Visible laser diode, diode housing, driver circuit, and collimation lens all factory assembled in one small module. Features an automatic power control circuit (APC) driver, Requires 3 to 4.5V <at> approx 50mA. Overall dimensions: 12mm X 34mm long. Bright enough for a Laser Light Show: (LM2) $8 SWITCH MODE POWER SUPPLY: Modern design compact (145 x 80 x 50mm), totally enclosed in a perforated metal case (black box shown in the white case). 240V AC in, 12V DC <at> 2A and 5V DC <at> 5A out. The power supply is installed within a flat PC type white powder coated metal box (380 x 365 x 55mm). Weight is 3.6kg: (PS5C) $20 COMPUTER POWER SUPPLY: New complete PCB assembly only. Overall dimensions are 45 x 108 x 200mm. Switchable 120/ 230V AC input. DC outputs are +5V<at> 6A, +12V<at>1A, -12V<at>1A, -5V<at>1A. Circuit provided, RU approval. Modern design. Mains input - Not for the inexperienced ! Be quick: (PS6) 4 for $24 LL A SM NEW PRODUCTS CMOS CAMERAS SUPER MICRO B/W mm Low light (0.2 Lux) 60 X Low intro price $120 mm Ask for plus free VHF 17 modulator with any camera purchase. B/W SUGAR CUBE m 4m (AND NOW AVAIL ABLE X1 6 1 IN COLOUR) 6X E1 Z SIZED CAMERA I S DRAWN ACTUAL SIZE The smallest monochrome camera we have offered yet. They don’t have the greatest resolution but are very small and only draws 10mA <at> 5V (a 9V bat. + regulator would run one of these for days) Camera in its own plastic housing plus free VHF modulator and suitable power adaptor for special intro price B/W...$90 COLOUR $160 CHECK OUT “CAMERAS” ON OUR WEB SITE FOR MORE DETAILS SIMPLE PIC PROGRAMER KIT BARGAIN: (Ref: SC March 1999) Learn to program your own 16F84 / 16F83 / 16C84 micro-controllers the easy way with this simple kit that just plugs into your PC's printer port and uses these (NEW) ProLine PS/2 MOUSE: small, cheap but powerful chips. Kit includes Ergonomically shaped for construction details, PCB and all on-board comfort. Supports plug & components, D25 connector and a PIC16F84 play. 600dpi.Comes IC. The NOPPP software that is required is not in its original box. A free inc. but is available on the net. (K128) mouse pad is supplied See bellow for with every mouse: $10 cable bargain.... PIC16F84BIG TRANSFORMERS 04P IC: Brand new military grade transformers in $12 EACH original wooden packing cases. 39KVA, 3 phase 440V Primary, 2 secondaries, 24v center tapped PROFESSIONAL PIC PROGRAMER KIT: at 326A, Electrostatic shield & Earth. All This is kit of parts uses Bojan Dobaj’s P16PRO secondary connections are bolted and strapped software to program all 8, 18, 28 & 40 pin DIP by heavy links (could be re-configured) 540mm serial PIC's. Parallel programmed PIC'sX600mm X 300mm. Weighs approx. 300Kg. 16C5X are not supported. The P16PRO $390 software runs under DOS, WIN 3.1 or 95/98. Don’t confuse these programming methods (NEW) HIGH VOLTAGE CAPACITORS: with the serial and parallel PC ports. The These military quality capacitors software needs to be downloaded from the are a rare find. They are 500pF / Oatley Website & registered for a small fee. 30kVDC and measure 81mm We supply 8, 18 & 40 pin IC sockets. Quick & long x 29mm diameter. The easy construction. PIC chips not inc. These are connections are via screw the PIC's that this kit will program: I2C5XX, terminals on each end : $9 each I6C67X, I2CE67X, 14000, I6C61, 715, 62, 62A, R62, 63, 64, 64A, R64, I6C65, 65A, 66, 67, ATX PC POWER SUPPLY: 620, 621, 622, 710, 71, 711, 72, 73, These NEW 90W LITEON Brand power PICI6C73A, 74, 74A, 76, 77, F83, R83, 84, supplies include logic level controlled mains F84, R84, PICI6C923, 924, 642, 662. For 64 switch and have pin PIC's - 16C92x & 17Cxxx - you will need an the following outputs adaptor from Microchip or make your own. +5V <at> 10A, -12V <at> (K129) $27...Just add $10 for a DB25 cable (25 0.2A, +12V <at> 1.5A, pins straight through). Valued at around $40 +3.3V <at> 6A. Input is 100-240V AC <at> 50KEYCHAIN LASER 60Hz via an IEC socket. POINTER 650nm: Has internal fan. Unit Supplied in a small metal weighs 1.3kg and measures cylindrical case that is 140 x 150 x 85mm: (PATX1) $15 fitted with a keychain. Powered by three LR44 WE HAVE FRESH STOCKS batteries (supplied): OF NEW 12V / 7Ah GEL (LPM2) $10 BATTERIES Priced at a fraction of their (NEW) PACKARD BELL KEYBOARD: real value. 65mm (W) X Standard 105-key Keyboard with a blue colour 150mm (L) X 94mm (H),with coded PS/2 plug. New & in original packaging. suitable trickle charger. $25 Weight is approximately 1.3kg: (099969) $12 ALSO WINDOWS KEYBOARDS AMP / HOUR CHARGER KIT: AVAILABLE, NEW BUT DUSTY $12 Just set the required current; 0.1, 0.3 or 0.5A and the time. Charger shuts off automatically Charges any cell or battery from 0 - 15V. Kit inc. PCB & all on-board components, suitable surplus box, knob, switches, timer, label & plugpack: (K144) $18 HOUSED VIDEO CAMERAS $32... 12V DC / 13W COMPACT FLUORESCENT These CFL's must not ELECTROLYTIC CAPACITOR TUBE: be installed in 240V AC sockets. (Edison Screw), centre positive. BARGAIN Quality brand ideal for power supply projects. Equivalent to a 75W incandescent lamp. 180mm long, 47mm 32mm X 16mm, 7mm lead spacing. maximum base diameter: $1ea or 10 for $7 (CFL12) $25 OVER 100 OF KITS ON OUR WEB ACN 068 740 081 PCB DESIGN AND PRODUCTION SERVICE CALL OR E-MAIL ”BRANKO” VERY COMPETITIVE PRICES FOR MORE DETAILS ON THESE AND MORE KITS SEE OUR WEB SITE major cards with ph. & fax orders, Post & Pack typically $6 CCD B/W IN SWIVEL CASE $99 PCB VIDEO CAMERAS B/W CCD CAMERAS $89 pinhole (60deg.), 92 deg,120 deg. add $10 for 150 deg. ASK FOR A FREE VHF MODULATOR AND PLUG PACK WITH EACH CAMERA Check out our “new look” web site for more products. Amazing cheap super bargains in our bargain corner & many other items that we can not fit on this page Prices subject to change Jwithout notice UNE 2000 25 ACN 068 740 081 ABN18068 740 081 SC_MAR_00 This neat little FM receiver is controlled by your PC and tunes the 144-148MHz amateur band. Alternatively, just by changing the software, you can use it to tune the 132-144MHz band for weather satellite frequencies or, with just a few hardware changes, the 118-132MHz band. PC-controlled VHF FM receiver Design by MARK ROBERTS, VK2GND I F YOU’RE LOOKING for a basic FM receiver capable of monitoring the 144-148MHz amateur band, this unit should do the job quite nicely. It’s all built on a PC board measuring just 90 x 74mm and plugs into your PC’s parallel port via a DB25 male-to-female printer cable. An on-screen display lets you control the receiver and does away with expensive hardware such as meters, digital displays and tuning knobs. You don’t even need to house the device in a case if you don’t want to, although a low-cost plastic case to protect the circuit would probably be the way to go. Fig.1 shows the on-screen display that’s used to “drive” the VHF Receiver. There’s really not much to it! The top half is dominated by the large digital frequency display and a tuning meter, while between these are three memory preset buttons and a large vertical fine-tuning “knob”. The bottom half of the display carries a Power button, a coarse tun- 26 Silicon Chip ing “knob” and squelch and volume slider controls. You tune the unit in 5kHz, 10kHz or 100kHz steps, either by dragging the tuning “knob” with the mouse or by clicking the Up and Down arrows on either side. Clicking anywhere on the circumference of the knob will also tune the receiver to that spot. The 5kHz, 10kHz or 100kHz tuning steps are selected by clicking the large buttons immediately to the right of the tuning knob. Clicking the top button toggles between the 10kHz and 100kHz tuning steps, while clicking the (misnamed) Help button selects 5kHz tuning steps. One nice feature of the unit is its ability to automatically scan the frequency band. Just click the Scan button, and the receiver automatically scans up the band, incrementing at the selected frequency steps. This scanning automatically stops when the received signal strength exceeds the squelch control setting. The functions of the Squelch and Volume controls are self-explanatory. As you’ve no doubt guessed, they are also adjusted using by dragging them with the mouse. As you drag the squelch control, the level is indicated by a dark-brown “bar” on the meter, so that you can instantly see the squelch setting in relation to the signal level. Finally, there are three memory buttons for you to store your favourite channels. All you have to do is tune to the required frequency, click the Read button and click the desired memory preset button (Ch-1, Ch-2 or Ch-3) and voila! ... the frequency is programmed in. Block diagram Fig.2 shows the block diagram of the VHF 144-148MHz FM Receiver. It’s built around a Motorola MC13135 radio IC, which is virtually a complete narrowband FM radio on a single chip. It drives an LM386 audio amplifier stage via a 4051 8-stage analog multiplexer, the latter providing the volume control function. Quite a lot of circuitry is packed into the MC13135, includ ing two local oscillators, a varicap tuning diode, two low-noise mixer stages, a high-gain limiter, a demodulator and a received signal strength indicator (RSSI) – see Fig.5. However, the first local oscillator isn’t used in this design as its maximum frequency is only about 100MHz. Instead, our circuit uses an external VCO (voltage con trolled oscillator) which is controlled by a PLL (phase locked loop). In operation, the PLL compares a divided-down VCO signal with a reference signal and, based on the phase error, produces a tuning voltage for the varicap diode inside the MC13135. The varicap diode sets the VCO frequency, which is pulled into lock with the divided reference. The analog-to-digital (A-D) converter stage is there simply to monitor the received signal strength and the external power supply rail. It converts these analog voltages to digital values so that they can be processed by the software and displayed by the onscreen instrument panel. The signal strength meter indi cates the RSSI in analog fashion, while the supply voltage is indicated in the bottom righthand corner of the meter. Dual conversion Before moving on to the circuit description, let’s take a closer look at the MC13135 receiver IC. This is a “dual conver sion” receiver and basically Fig.1: this is the on-screen virtual instrument panel that’s generated by the VHF FM Receiver software. You tune the unit (in 5kHz, 10kHz or 100kHz steps) by dragging the tuning knobs or by clicking the Up and Down arrows. functions just like a conventional superhet but with one important difference. A conventional superhet receiver has only one local oscillator and this is mixed (or heterodyned) with the incoming FM signal to produce an intermediate frequency (IF). This IF signal is then amplified and filtered before being demodulated to recover the desired audio signal. This is referred to as a single conversion and the IF is typically 10.7MHz for FM receivers and 455kHz for most AM receivers. By contrast, a dual conversion receiver has two local oscillators (LO), two mixers and two intermediate frequencies. The first LO is mixed with the incoming signal to produce an IF of 10.7MHz. This is then ampli- fied and mixed with the second LO operating at 10.245MHz to produce a second IF of 455kHz (ie, 10.7MHz 10.245MHz = 455kHz). Dual conversion receivers are commonly used for narrowband FM reception, where the deviation is typically only ±5kHz (as compared to ±75kHz for commercial FM radio stations). Circuit details OK, now let’s take a look at the main circuit diagram (Fig.3). The incoming RF signal is picked up by the antenna and fed to first mixer input (pin 22) of IC3 via C4 and an LC filter network. This filter is tuned using trimmer capacitor VC1, while C6 (22pF) sets the bandwidth. Transistor T1 forms the external local oscillator. This voltage con- Fig.2: the VHF FM receiver is controlled via the parallel port of a PC. A dual-conversion FM receiver chip (IC3) forms the heart of the design and this is tuned using a PLL and external voltage controlled oscillator (VCO). JUNE 2000 27 28 Silicon Chip 2000 SC DB1 R7 2.7k R14 1M 18 4 2 A1 12 16 GND VAG 5 VHF FM RECEIVER 7 6 5 4 3 +5V 16 C B A +5V 13 R23 1.5k C18 56pF C17 120pF Y1 14 R22 2k C20 .01F 12 4 VCC1 R20 5.6k Y5 5 R19 6.8k DECOUP2 DECOUP1 1stMIXOUT 1stMIXIN2 1stMIXIN1 Y6 2 E Z VEE Y7 4 8 7 6 3 AMPOUT AMPIN- AUDIO AMPIN+ RSSI QUADIN 2ndMIXIN GND R18 3.3k 8 GND 19 VCC2 IC3 MC13135 2ndMIXOUT LIMITIN 2ndLOB 2ndLOE VARICAPa VARICAPc 1stLOB 1 Y4 IC4 4051B Y3 11 10 7 9 6 5 23 24 1 R21 2.7k C19 .01F 4 2 R8 2.7k 15 Y2 3 1 XTAL2 10.245MHz F1 455kHz CERAMIC FILTER C33 0.1F Y0 VDD R24 1.2k 9 8 R4 2.7k R16 12k +5V 1 9 13 10 1 C26 .01F 11 11 A0 R6 39k TP1 10 12 R12 56k C15 0.47F R11 2.7k R13 100k T2 MPSH10 R17 560 E C C16 22pF 14 K IC1 MC145041 R5 330k GND VDD +5V 13 B T1 MPSH10 A10 A9 A8 A7 A6 A5 A4 A3 A2 SCLK DIN DOUT CS 20 VDD +5V 14 R25 2.7k OSCOUT OSCIN VREF 2 PDOUT 4 FIN E C10 120pF R9 560 IC2 MC145170-2 CLK ENB DIN C8 8.2pF B C +5V 17 LED1 17 3 A 16 9 15 2 REF LM385Z-2.5 _ + 10 C12 3-12pF 7 6 1 5 6 XTAL1 8MHz E2 470F 16VW 7 C11 68pF E4 10F 16VW +5V C7 22pF R10 C9 100k 56pF 8 5V DC INPUT _ + D1 IN4001 L3 C14 330pF +5V G 2 3 1 S D _ + ADJ CATHODE LM385Z F3 455kHz QUAD COIL L1 C6 22pF 2N7000 E B C MPSH10 D G S +5V C4 10pF R15 12k C29 .001F 2 3 4 1 IC5 LM386 6 +5V 7 SPEAKER 8 E3 470F 16VW 5 C2, C13, C23, C25, C28, C34, C35, C116 ALL 0.1F +5V F2 10.7MHz CERAMIC FILTER V1 5-60pF C21 120pF T3 2N7000 R1 16k C22 0.1F R3 1k C27 .01F C3 .01F +5V C24 0.1F 16 15 17 14 12 13 18 20 21 22 ANTENNA Fig.3 (facing page): the full circuit diagram of the VHF FM Receiver. The dual conversion receiver (IC3) is tuned by the external VCO (IC2) and the PLL (IC1). The demodulated audio output appears at pin 17 and drives audio amplifier IC5 via IC4 which functions as the volume control. trolled oscillator (VCO) is tuned by the varicap diode between pins 24 & 23 of IC3, along with C14 and inductor L3. The output appears at T1’s emitter and is fed to the LO input (pin 1) of IC3 via C16 where it is mixed with the received RF signal. In operation, the VCO runs at between 154.7MHz and 158.7MHz (ie, 10.7MHz higher than the received frequency), depending on the capacitance of the internal varicap diode. After mixing with the antenna signal, the first IF at 10.7MHz is filtered by ceramic filter F2 and then fed to pin 18 (mixer 2) of IC3 where it is mixed with the second local oscillator. The second local oscillator operates at 10.245MHz, as set by crystal XTAL2 and its associated capacitors. As a result, the second IF is at 455kHz and this is filtered using ceramic filter F1 which has a bandwidth of 12.5kHz. This second filter limits any out-of-band noise and increases the selectivity. Following F1, the signal is fed to an internal limiting circuit and then to a quadrature demodulator. F3 is the external quadrature coil and is tuned during the adjustment procedure to 455kHz using a ferrite slug. The recovered audio signal appears at pin 17 of IC3 and is fed via R3 & C22 to the top of a resistive divider network (R18-R24). The eight steps of this resistive divider are fed to the Y0-Y7 inputs of the 4051 analog multiplexer (IC4) which we’re using as the volume control. This IC is controlled by a 3-wire interface from the PC’s parallel port (LPT1). The control signals are applied to the binary control inputs at pins 11, 10 & 9 (designated A, B & C) of IC4 and select which of the eight input channels is switched through to the output at pin 3. Basically, IC4 functions as a single-pole 8-position switch. It selects one of the possible eight signal levels and applies it to pin 3 of the following LM386 audio amplifier stage (IC5). Parts List 1 PC board, 90 x 74mm 1 PC-mount DB25 male connector 1 455kHz ceramic filter, 12.5kHz bandwidth (F1; see text) 1 10.7MHz ceramic filter 1 8MHz crystal (Xtal1) 1 10.245MHz crystal (Xtal2) 1 5-65pF trimmer capacitor (V1) 1 3-13pF trimmer capacitor (C12) Semiconductors 1 MC145041 8-bit A-D converter (IC1) 1 MC145170-2 PLL synthesiser (IC2) 1 MC13135 dual conversion FM receiver (IC3) 1 4051B 8-channel analog multiplexer (IC4) 1 LM386 audio amplifier (IC5) 2 MPSH10 VHF NPN transistors (T1,T2) 1 2N7000 N-channel MOSFET (T3) 1 1N4001 diode (D1) 1 LM385/2.5 2.5V reference (REF) 1 miniature LED (LED1) Inductors L1 5T of 0.7mm ECW on 3mm former L3 5T of 0.7mm ECW on 3mm former F3 455kHz quadrature coil (F3) IC5 operates with an AC gain of 20 by virtue of its internal feedback components. The amplified output appears at pin 5 and is coupled to the loudspeaker via a 470µF capacitor. Tuning The tuning for the receiver is controlled by IC2 which is a Motorola MC145170 PLL frequency synthesiser. Its internal reference oscillator operates at 8MHz due to crystal XTAL1, although this can be “tweaked” slightly using trimmer capacitor C12. This reference frequency is divided down by an internal 15-stage counter to either 100kHz, 10kHz or 5kHz, depending on the required tuning steps. Emitter follower T2 buffers the VCO output and feeds the signal to the FIN input of IC2 via C10. We won’t go into all the inner workings of the Capacitors 2 470µF 16VW electrolytics (E2, E3) 1 10µF 16VW electrolytic (E4) 1 0.47µF ceramic (C15) 11 0.1µF ceramic (C2, C13, C2225, C28, C33-35, C116 5 .01µF ceramic (C3, C19-20, C26-27) 1 .001µF ceramic (C29) 1 330pF (C14) 1 120pF (C10, C17, C21) 1 68pF (C11) 1 56pF (C9, C18) 1 22pF ceramic (C6-7, C16) 1 10pF ceramic (C4) 1 8.2pF ceramic (C8) Resistors (0.25W, 1%) 1 1MΩ (R14) 1 330kΩ (R5) 2 100kΩ (R10, R13) 1 56kΩ (R12) 1 39kΩ (R6) 1 16kΩ (R1) 2 12kΩ (R15, R16) 1 6.8kΩ (R19) 1 5.6kΩ (R20) 1 3.3kΩ (R18) 1 2.7kΩ (R4, R7, R8, R11, R21, R25) 1 2kΩ (R22) 1 1.5kΩ (R23) 1 1.2kΩ (R24) 1 1kΩ (R3) 1 560Ω (R9, R17) MC145170 here; suffice to say that the VCO frequency is divided down using a 16-stage counter. The phase of the divided VCO signal is then compared to the divided reference signal to generate an error voltage at the pin 13 phase detector output (PDOUT). This voltage is filtered using a low-pass filter made up by R11, R12, C15 and C26. This then becomes the tuning voltage and is applied to the varicap diode inside IC3 via R13. What happens in practice is that the PLL tunes the VCO so that its divided frequency exactly matches the divided reference frequency – either 100kHz, 10kHz or 5kHz. Controlling the PLL The PLL is itself controlled by a 3-wire interface from the parallel port to pins 5 (DIN), 6 (ENB) and 7 (CLK). JUNE 2000 29 C9 L3 C14 TP1 Fig.4: follow this parts layout diagram to build the 144148MHz and 132-144MHz versions of the VHF FM Receiver. The component side of the PC board is shown in grey, while the underside pattern is in blue. The corre sponding control outputs on the parallel port are pins 8, 7 & 6. DIN is the serial data input and the number of bits clocked in determines which registers are accessed to set the division ratios for the internal 15-stage and 16-stage counters. Pin 7 is the clock (CLK) input to the MC145170, while pin 6 (ENB) is the enable input. When pin 6 of IC2 is taken low, the data on pin 8 of the parallel port is clocked into the DIN input to set the division ratios for the This photograph shows the completed PC board assembly and will assist you to identify the parts. The parts that have to be changed for the 118-132MHz version (C9, C14 and L3) are indicated with red arrows. counters. OK, now that might all sound terribly complicated in theory but in reality, it’s quite simple. To set the tuning steps, the data on the parallel port (as generated by the software in response to user inputs) sets the appropriate division ratio for the 15-stage counter. Let’s say that we want 100kHz steps. In that case, we have to divide the 8MHz reference frequency by 80. If we want 10kHz or 5kHz steps, then we have to divide by 800 or 1600 respectively. Now let’s say that we want to tune the receiver to 146MHz and that we have selected 100kHz steps. To receive this frequency, the VCO must be tuned to 156.7MHz (ie, 10.7MHz higher) and so the 16-stage counter must be set so that it divides 156.7MHz down to 100kHz exactly; ie the counter must be set to divide by 1567. If we now select a frequency of 146.1MHz, the software sets the Table 1: Resistor Colour Codes  No.  1  1  2  1  1  1  2  1  1  1  1  1  1  1  1  1 30 Silicon Chip Value 1MΩ 330kΩ 100kΩ 56kΩ 39kΩ 16kΩ 12kΩ 6.8kΩ 5.6kΩ 3.3kΩ 2.7kΩ 2kΩ 1.5kΩ 1.2kΩ 1kΩ 560Ω 4-Band Code (1%) brown black green brown orange orange yellow brown brown black yellow brown green blue orange brown orange white orange brown brown blue orange brown brown red orange brown blue grey red brown green blue red brown orange orange red brown red violet red brown red black red brown brown green red brown brown red red brown brown black red brown green blue brown brown 5-Band Code (1%) brown black black yellow brown orange orange black orange brown brown black black orange brown green blue black red brown orange white black red brown brown blue black red brown brown red black red brown blue grey black brown brown green blue black brown brown orange orange black brown brown red violet black brown brown red black black brown brown brown green black brown brown brown red black brown brown brown black black brown brown green blue black black brown 16-stage counter to divide by 1568 and the tuning voltage generated on pin 13 of the PLL “pulls” the VCO into lock so that it now runs at 156.8MHz. A-D converter IC1 is an 8-bit A-D converter with 11 analog input channels (A0-A10). It is used here to monitor the received signal strength and the external supply voltage. As shown, the RSSI output from IC3 appears at pin 12 and is fed to pin 14 which is the non-inverting input of an internal op amp. The buffered output appears at pin 16 and is fed via R4 to the A0 (pin 1) input. Similarly, the supply voltage is sampled using R5 and R6 and the divided voltage applied to the A1 input. An LM385Z-2.5 (REF) sets the reference voltage to 2.5V on pin 14 of the A-D converter (IC1). The latter is controlled via a 3-wire interface from the PC to pins 15, 17 & 18, while the data is clocked out of pin 16 and applied to pin 10 of the parallel port. Transistor T3 is used to mute the receiver. This transistor is controlled via pin 5 of the parallel port and turns on to mute the audio from IC3 as required. Finally, pin 9 of the parallel port controls the power indicator LED (LED 1) via R7. This is turned on and off via the power switch on the front panel. Table 2: Capacitor Codes            Value IEC Code EIA Code 0.47µF 470n 474 0.1µF 100n 104 .01µF 10n 103 .001µF 1n 102 330pF 330p 330 120pF 120p 120 68pF 68p 68 56pF 56p 56 22pF 22p 22 10pF 10p 10 versions. Start the assembly by installing all the resistors, the capacitors and the ICs. Table 1 shows the resistor colour codes, while Table 2 shows the codes for the MKT polyester and ceramic capacitors. It’s also a good idea to check each resistor on a digital multimeter, just to make sure you have identified it correctly. Keep all component leads as short as possible, to avoid stray capacitance and inductance effects. Next, install the three transistors (T1-T3), followed by the ICs which should be are directly soldered to the PC board. Take care to ensure that these parts are all orientated correctly and don’t get them mixed up. In particular, note that T3 is a 2N7000 MOSFET, while T1 & T2 are MPSH10 bipolar types. Now for the two inductors (L1 and L3). These are both made by winding five turns of 0.7mm enamelled copper wire (ECW) onto a 3mm former (eg, a 3mm drill bit). After winding each coil, slide it off the drill bit, scrape away the enamel from its leads and push it all the way down onto the PC board before soldering. The turns should be evenly spaced so that each coil is about 9mm long. Now complete the assembly by installing the two ceramic filters (F1 & F2), the two crystals, the quadrature coil (F3), the trimmer capacitors (V1 & C12), the DB25 connector and the power supply terminal block. You can also install pin headers for the loudspeaker and antenna connections. Note that if you want to receive weather satellite pictures on 136MHz, ceramic filter F1 (455kHz) should have a bandwidth of 50kHz (these filters are available from Jaycar and Dick Smith Electronics). 118-132MHz version In addition to changing the software, three component changes are Power Power for the circuit is derived from an external 5V supply. This supply must be well regulated; eg, by using a 5V 3-terminal regulator. Note that a 5V plugpack isn’t good enough, since its regulation will be quite poor. Diode D1 is there to provide shortterm reverse polarity protection. A 100mA fuse should be included in the supply line if the supply isn’t short-circuit proof. Typically, you could use a 9V AC or DC plugpack or 9V battery to the regulator. Fig.5 shows a suitable circuit, with an optional LED power indicator. Construction Building the VHF FM Receiver sure is a lot easier than understanding how it works. All the parts, except for the loud speaker, are mounted on the PC board and the alignment is easy. Fig.4 shows the assembly details for the 144-148MHz and 132-144MHz Fig.5: the MC13135 radio IC is virtually a complete narrowband FM radio on a single chip. It’s a dual conversion receiver with two local oscillators (LO), two mixers and two intermediate frequencies (IFs). It also includes a varicap tuning diode, a high-gain limiter, a demodulator and a received signal strength indicator (RSSI). JUNE 2000 31 Fig.5: this simple regulator circuit will let you power the receiver from a 9V AC plugpack. Alternatively, you could use a 9V DC plugpack or a battery pack to directly feed the 7805 regulator and eliminate the four rectifier diodes. required if you want to tune from 118-132MHz: change C9 to 22pF; change C14 to 1500pF; and use six turns for coil L3. These parts are all in the VCO and the component changes are necessary so that it now tunes over its new range from 128.7MHz to 142.7MHz. Software The software runs under Windows 95/98 but not under Windows 3.1x. The main software version covers the range from 144-148MHz and is provided with the kit (see panel). Range updates for 132-144MHz and 118-132MHz bands are also available and can be downloaded free of charge from the SILICON CHIP website at www.siliconchip.com.au or from Softmark’s website at www.ar.com. au/~softmark Note that there are three range updates to choose from: 144vhf.zip for the 144-148MHz band; 132vhf.zip for the 132-144MHz band; and 118vhf.zip for the 118-132MHz band. You install the main program by running setup.exe. This will install the various files into a folder named C:\Program Files\FM-Receiver (you can change this if you want to) and install the necessary entries in your Start menu. To install the range updates, first unzip the file, then run the “.exe” file. Note that the updates only work if you have the main program installed on your computer. Test & alignment Connect the receiver to your PC and to a loudspeaker, apply power from an external 5V DC source (eg, batteries), Note To keep costs low, the interface to the parallel port has been kept very simple, with no surge protection fitted for the external circuitry. For this reason, we suggest that you use a short cable (say less than 1-metre long) to connect the VHF FM Receiver to the parallel port. In addition, you should always apply power to the VHF FM Receiver first, before booting the computer and loading the software. The reverse order applies when switching off – ie, turn off the computer first before removing power from the receiver. Where To Buy The Parts A full kit of parts for this design is available from Softmark, PO Box 1609, Hornsby, NSW 2077. Phone/fax (02) 9482 1565; email softmark<at>ar.com.au Full kit (hardware and software; specify CD-ROM or floppy disks)....................... $85 Payment by cheque or money order only. Please add $6 for postage. Range updates can be downloaded free of charge from the Softmark website at www. ar.com.au/~softmark or you can download from the SILICON CHIP website at www. siliconchip.com.au Note 1: the above prices do not include GST which comes into force on 1st July, 2000. Note 2: copyright of the software and PC board associated with this project is owned by Softmark. 32 Silicon Chip then boot the computer and run the software. The software will ask you which parallel port you wish to use (either LPT1 or LPT2), after which you turn the on-screen display on by clicking the power button. Assuming that everything is working OK, the first step in the alignment procedure is to adjust coil L3 so that the VCO tunes the required range. To do this, adjust the tuning so that the on-screen display reads 146.000MHz and stretch (or squeeze) L3 so that the voltage at test point TP1 is 2V (see photo for location of test point). Now tune the receiver across its entire range. The voltage at TP1 should vary from about 0.2V at 144MHz to about 4.0V at 148MHz. It should never be at 0V or at 5V. Similarly, for the other two frequency ranges, simply tune to the centre of the band and adjust L3 for 2V at TP1. The next step involves adjusting L1 and trimmer capacitor V1. This involves tuning to a station that you can receive and adjusting these two components for maximum signal strength, as indicated on the meter. Initially, you should try setting V1 to mid-position; if you find that V1 is at the end of its travel for maximum signal level, try adjusting L1. Alternatively, you can use a VHF signal generator if no on-air stations are available. Don’t connect the generator directly to the receiver though. Instead, attach a 200mm antenna to the generator’s output and attach a similar length of wire to the antenna input of the receiver. Adjust V1 and L1 as described above. Next, the quadrature coil (F3) should be adjusted for best audio quality. You will probably find that the ferrite slug will be just proud of the top of the can but note that this adjustment isn’t particularly critical. Frequency calibration Trimmer capacitor C12 provides the frequency calibration. To do this, tune to a station or repeater of known frequency and adjust C12 so that the indicated frequency is correct. Alternatively, if you have an accurate frequency meter, you can adjust C12 so that the reference frequency is exactly 8MHz. Note that you will have to use a sniffer probe to pick up the oscillator signal, as a direct connection will provide enough loading to shift the frequency one way. SC PRODUCT SHOWCASE Marantz announce four new DVDs Three new high-performance DVD players have recently been released while a new entry-level model is due later this year. The Marantz Reference Series DV-18 is designed for the ultimate video and audio performance. It’s THX Ultra certified and features 10-bit/27MHz video D/A conversion, component video outputs and 96/24 audio capability. It is also equipped with Dolby Digital and DTS and has a full complement of viewing options and interactive capabilities offered by the DVD-Video format, including multiple camera angles and aspect ratios. Retail price is $2490. The $1790 DV7000 is similar but not part of the reference series, while the $1299 DV4000 is designed for spectacular home theatre video and surround sound audio quality. The entry-level DV3100 is expected to retail for around $1000. All Marantz DVD players also play back video CD and CD-R. D-BUS remote connection allows linkage to other Marantz components for inte- Oxley amateur radio field day The annual field “day” for the Oxley Region Amateur Radio Club Inc will be held on the Queen’s Birthday weekend, 10 and 11 June, at the Sea Scout Hall, Buller St Port Macquarie. Always a much-anticipated event amongst amateur operators from the Oxley region (and much further afield), the field day will feature amateur-oriented events, displays and demonstrations - and you could win a year’s subscription to SILICON CHIP! Field day opening times are 1.30 on Saturday and 8.30 on Sunday. For more information, contact the secretary, Alan Nutt, on (02) 6582 3557 or email anut<at>oze-mail.com.au An interesting case (or two)… Looking for somewhere to put all those bits and pieces? We reckon these two new component storage boxes from Jaycar are a real bargain! Both are priced at just $9.95, made from plastic and for that you get either a large (370 x 280 x 65mm), single sided case with 24 compartments, a flip-top lid and handle; or a smaller (290 x 305 x 70mm) double-sided case with 32 compartments (22 one side, 10 the other), two flip-top lids and a carry handle. In both cases (no pun intended!), some of the internal dividers are removable to give you larger, fewer compartments. If that’s still not enough space, we believe a little surgery on the fixed dividers would have the sizes and shapes desired. The lids are nearly transparent so you can see what’s inside before opening up. Apart from components, the cases would be ideal for small-ish test instruments (or large if you remove some dividers). The larger box is cat. HB-6314 while the smaller is cat. HB6315. You can see these storage boxes at any Jaycar electronics store and many of their dealers. They can also be ordered from Jaycar mail order (02 9743 5222) or web site (www. jaycar.com.au). grated system operation while features such as parental control, slow motion, freeze frame, multi-speed forward and reverse scan, chapter and track search functions are all standard. Marantz audio equipment is available at better sound and video outlets. For more information or the dealer closest to you, contact Jamo Australia on 1800 24 24 26. Compact digital scale At just 130 x 80mm, the new digital Pocket Scales from Dick Smith Electronics are just that: able to fit in a (well, OK large) pocket. They can measure up to 100g with 1g resolution – and with simple and fast calibration, they’re sure to find many uses in the home, office, business and industry. They feature a large, easy-toread LCD screen and are very easy to use. A carry pouch and set of batteries are included. The Cat Y-5039 Compact Pocket Scales are priced at $199 and are available from all Dick Smith Electronics stores, DSE PowerHouse stores, DSE Direct Link mail order (1300 366 644) or via the website at www.dse.com.au PLEASE NOTE Any prices mentioned in this issue are current for this issue only. The introduction of GST in Australia on July 1 will have an influence on many prices, particularly on items which are currently tax exempt. For prices after July 1, please contact the company concerned. JUNE 2000 33 B BEF UY RE JUNO E & AV 30 OID G S *o *on T n tth !ucc*t he esse ep prro od du tss o YOUR DETAILS Order Form/Tax Invoice Silicon Chip Publications Pty Ltd ABN 49 003 205 490 PRICE GUIDE- Subscriptions on nly ly Your Name________________________________________________________ (PLEASE PRINT) Organisation (if applicable)___________________________________________ Address__________________________________________________________ (all subscription prices INCLUDE P&P and GST) Please state month to start. Australia: 1 yr ....................$A69.50 1 yr + binder .....................$A83 NZ (air): 1 yr .....................$A77 Overseas (surface): 1 yr ....$A85 Overseas (air): 1 yr ...........$A125 PRICE GUIDE- Other products (GST is NOT included: GST will be added to all orders received after 30 June 2000) _________________________________________________________________ Postcode_____________ Daytime Phone No. ( )_____________________ Email address (if applicable) ___________________________________________ Method of Payment:  Cheque/Money Order  Bankcard  Visa Card  Master Card 2 yrs .....................$A135 2 yrs + 2 binders ..$A159 2 yrs .....................$A145 2 yrs .....................$A160 2 yrs .....................$A250 *BACK ISSUES in Stock: 10% discount for 10 or more issues. Australia: $A7 ea (including p&p by return mail) NZ: $A8 ea (inc p&p by air); Elsewhere: $A10 ea (inc p&p by air). *BINDERS: BUY 5 or more and get them postage free. (Available in Aust. only.) ..........................$A12.95 ea (+$5.00p&p). *SOFTWARE: $7.00 per item (project) plus $3.00 p&p per order within Australia, $5.00 p&p per order elsewhere. (Most software is available free on www.siliconchip.com.au). *ZOOM EFI TECH SPECIAL $A8.95 inc p&p Aust/NZ, $11.95 inc p&p elsewhere *COMPUTER OMNIBUS: $A12.50 inc p&p Australia; NZ/Asia/ Pacific $A15.95 inc p&p (air); elsewhere $18.95 inc p&p (air). Card No. *SILICON CHIP/JAYCAR WALLCHART: Unfolded (in mailing tube): $A9.95 including p&p (Australia only) – unfolded version not available elsewhere. Folded: $A5.95 inc p&p within Australia; elsewhere $A10 inc p&p Card expiry date Signature_____________________________ *BOOKSHOP TITLES: Please refer to current issue of SILICON CHIP for currently available titles and prices as these may vary from month to month. SERVICES# SUBSCRIBERS QUALIFY FOR 10% DISCOUNT ON ALL SILICON CHIP PRODUCTS AND SERVICES* #except subscriptions/renewals and Internet access Item Price Qty Item Description P&P if extra Total Price Total $A TO PLACE YOUR ORDER 34 Silicon Chip Phone (02) 9979 5644 9am-5pm Mon-Fri Please have your credit card details ready OR Fax this form to (02) 9979 6503 with your credit card details 24 hours 7 days a week OR Mail this form, with your cheque/money order, to: Silicon Chip Publications Pty Ltd, PO Box 139, Collaroy, NSW, Australia 2097 06-00 “Y” Adaptors from Microgram Ever needed to run two monitors – or even two keyboards – from one PC? Perhaps you have a notebook and want to use and external keyboard and mouse but only have one PS-2 port? These, and other combinations of computer peripherals, are made simple with this range of “Y” adaptors. Each adaptor is supplied with instructions and all necessary leads, in some cases extra leads for alternative socket arrangements (eg, the dual keyboard adaptor has leads to suit both 5-pin and 6-pin sockets). There are five products in the range, with their names suggesting their application: “Y-mouse” dual PS/2 mouse adaptor (Cat 15090 <at> $119), “Y-mouse” PS/2 keyboard & mouse adaptor (Cat 15093 <at> $179), “Y-mouse” USB keyboard & mouse adaptor (Cat 15094 <at> $149), “Y-see 15W CLASS A AMPLIFIER 80VA for single channel monoblock 240:2x21V/1.9A 160VA for amplifier as published 240:2x21V/3.8A 160VA low flux design + flux band 240:2x21V/3.8A 160VA low flux design + flux band 240:2x42Vct/1.9A ULTRA LOW THD 100W AMPLIFIER 160VA for single channel monoblock 240:2x35V/2.25A + 2x50V/0.1A 300VA for dual channel amplifier 240:2x35V/4.5A + 2x50V/0.1A $35.45 $42.50 $65.90 $74.40 $50.70 $60.45 500W MONO AMPLIFIER, as published 800VA two” dual monitor adaptor (Cat 15092 <at> $229) and “Y-key-key” dual keyboard adaptor (Cat 15091 <at> 119). For more information contact Microgram Computers, Unit 1, 14 Bon Mace Close, Berkely Vale NSW 2261. Phone (02) 4389 8444, Fax (02) 4389 8388, email info<at>mgram.com.au, website www.mgram.com.au Grab a bargain at Rall Electronics Rall Electronics are currently holding a one-off sale of used electronic test instruments and production equipment. Items on offer include a 1GHz oscilloscope, a 100MHz digital oscilloscope, an optical power meter and a 20MHz oscilloscope for $295 (normally sells for $500+). Other gear available, all on a first-come, first-served basis, includes gauss meters, TOROIDAL TRANSFORMERS FOR SILICON CHIP AMPLIFIERS geiger counters, protocol analysers, RF power meters, multimeters, signal generators, insulation testers, modulation meters, frequency counters, oscilloscopes, power supplies and many more interesting instruments. Everything must be sold. For more details, visit the Rall Electronics’ website: www.rall.com.au, or call (02) 9489 2745. 240:2x57V/7A $134.50 All prices include WST. Freight extra. HARBUCH ELECTRONICS PTY LTD Ph 02 9476 5854 Fx 02 9476 3231 US Standards on CD Global Info Centre has released the American Society of Testing and Materials’ entire 75 volumes of standards, for the first time on CD-ROM. The 2000 edition of the Book of Standards contains new and significant revisions to existing standards along with specification documents, test methods, classifications etc. CD ROM provides a compact alternative to storing 75 volumes of text and, more importantly, provides easier access to the information. Contact IHS Australia Pty Ltd, Locked Bag 7, Eastwood NSW 2133. Freephone 1800 062 299, Freefax 1800 817 716, email gic<at>ihs.com.au Free “DriveWay” microcontroller development software from Motorola Developers using the 8-bit 68HC05 microcontroller family can now automatically build device drivers, boot and glue code that meet their precise specifications through an easy-to-use point and click Interface following the release of “DriveWay” software by Motorola and Aisys. The free DriveWay software, available for download from http:// mcu.motsps.com, enables the fast and easy integration of peripheral devices into designs and eliminates the need to learn the internals of each 68HC05 MCU derivative, resulting in faster development of higher quality applications. The key benefits of the Drive- Way software include an automatic assembly code generation for initialization code that automatically produces highly-tuned, fully-tested and documented code in minutes for each on-chip peripheral, while eliminating software, driver and initialisation software defects. Designers can now concentrate on generating their application code instead of the MCU configuration saving valuable development time. Another benefit is the point and click feature for setting up peripheral devices. In developing initialisation code and device driver interfaces, programming time can be reduced from weeks to minutes. DriveWay software is also de- signed to quickly confirm that an MCU can be configured for a specific application or suggest an appropriate one. It does this by selecting one 68HC05 from a group of 68HC05 MCU derivatives. In a matter of minutes, designers will be able to determine which 68HC05 provides the best solution. The first release of DriveWay software, available now, supports the most popular 68HC05 MCUs. Later this year, Motorola will be releasing DriveWay software for the 68HC08 and other MCU architectures. For further information or downloading visit the Motorola website nominated above. JUNE 2000 35 Aussie DesignMark award to Power Tower Elsafe Aust r a l i a ’s P o w e r Tower, a clever stowaway unit designed to provide worktop access to power and data, was awarded an Australian Design-Mark at the recent Australian Design Awards in Sydney. By pulling the grommet lid up on the unit, access can be gained to up to four GPOs or two GPOs and four data circuits. Multiple power and data cables are neatly hidden away. Products which receive this award are judged on their functionality and how it relates to ergonomics, aesthetics, creativity, originality, safety and environmental considerations. Manufacturing (construction and use of materials), price, packaging and marketability are also taken into account. Over two years in development, the Power Tower was also awarded “The Product Most Likely to be Commercially Successful” award at the commercial furniture industry’s bi-annual awards. For more information on the Power Tower, contact Elsafe Australia on (02) 9975 7422; fax (02) 9975 4733. New Shure UHF wireless microphone receiver With the planned withdrawal of most VHF radio microphone frequencies to make way for digital TV, a new high-performance Shure UHF wireless microphone receiver from Jands Electronics is timely. The UP4 Portable UHF Receiver offers over 100 easily-selectable frequencies in a sturdy package designed for on-road use. It comes in an extruded aluminium chassis with a mounting box of solid aluminium alloy which allows battery changes without removing the receiver. A single 9V battery gives up to 10 hours of continuous operation. The unit has microprocessor-controlled predtictive diversity which anticipates dropouts before they NI’s worldwide measurement conference Want to escape Australia preOlympics? National Instruments might have just the place for you: Austin, Texas, the venue of its worldwide conference on computer-based measurement and automation. “NIWeek 2000 – Get Connected” takes place from August 16 - 18 at the Austin Convention Centre. We’re not sure about the mathematics of three days making a week but NIWeek is designed for engineers and 36 Silicon Chip scientists involved with measurement and automation applications, systems integrators and developers, instrument manufacturers and members of the NI Alliance Program. Eighty measurement and automation vendors will also show their wares in a major exhibition. If you’re interested, contact National Instruments for a copy of their INWeek 2000 CD which explains all. Call (03) 9879 5166, fax (03) 9879 6277, email genevieve.hitchens<at>ni.com Thin PC boards Cordless phone headset A lightweight headset, specifically intended for 900MHz and 2.4GHz “long range” cordless phones, is available from Dick Smith Electronics stores. With an adjustable ear-piece and boom microphone, the headphone plugs straight into many brands of cordless phones including many Uniden, Panasonic, Telstra and DSE models with a “stereo” 2.5mm socket. It automatically creates a “hands free” cordless phone for added flexibility in this latest generation of cordless phones which are superior in most respects to the lower frequency, and therefore shorter range, cordless phones which have been available for some years. Being digital transmissions, eavesdropping via a scanner is said to be impossible. While not suggested in the material occur and also has tone key circuitry to block other RF signals and noise squelch to prevent noise bursts. It is compatible with Shure’s UC and U series of UHF transmitters which include body-pack, lavalier and handheld mic options. And while on the subject of Jands Electronics, the company has recently acquired the agency for Stanton Magnetics, a US manufacturer of premium DJ products. They are a market leader in cartidges and stylii but also offer turntables, mixing consoles, headphones and CD players. For more information contact Jands Electronics on (02) 9582 0909; fax (02) 9582 0999. supplied by DSE, we imagine that a headset of this type might have many applications apart from cordless phones - radio communications (including amateur radio) being one such possibility. However, you’re on your own with these uses! Priced at $28.50, the Cat F-7032 Cordless Phone Headset is available from all Dick Smith Electronics stores, DSE PowerHouse stores, DSE Direct Link mail order (1300 366 644) or via the website at www.dse.com.au Computronics Corporation have available a range of PC board material presensitised with positive photo-resist which is ideal for in-house prototypes. Of particular note are their thin blanks, down to just 0.6mm thick. In the range is single and double-sided fibreglass blanks with 1oz copper, from 0.6mm to 1.6mm substrates, with each 150 x 300mm sheet separately packed with an additional light-tight cover over the surface. There is also an ultra-thin 0.4mm substrate doublesided fibreglass board, a 1.6mm, 2oz copper fibreglass board and a 1.6mm, 1oz phenolic single-sided board. For more information contact Computronics Corporation, Locked Bag 20, Bentley Business Centre, WA 6983. Phone (08) 9470 1177, Fax (08) 9470 2844, website www.computronics. com.au/tools LECTRONICSHOWCASELEC at CHEAP CHEAP CHEAP PRICES! ICs, LCD Displays,Transistors, Diodes, Leds, Books, Connectors, Switches, Transformers, Fans, Relays, Speakers,Terminals, Resistors, Buzzers, Leads, Knobs, Batteries, Computer Accs. etc. FOR A FREE MONTHLY MAILER PLEASE CONTACT ROCOM ELECTRONICS EMC Technologies' internationally recognised Electromagnetic Compatibility (EMC) test facilities are fully accredited for emissions, immunity and safety standards. EMC Technologies Melbourne: (03) 9335 3333 Sydney: (02) 9899 4599 Email: sales<at>rocom.com.au NEW! HC-5 hi-res Vi deo Distribution Amplifier DVS5 Video & Audio str Di ibution Amplifier Five identical Video and Stereo outputs plus h/phone & monitor out. S-Video & Composite versions available. Professional quality. SALE SURPLUS TEST EQUIPMENT HANDBOOKS & SERVICE MANUALS STORE ADDRESS: 56 RENVER ROAD, CLAYTON VIC. 3168 POSTAL ADDRESS: BAG 620 CLAYTON SOUTH, VIC. 3169 PH (03) 9543 7877 FAX (03) 9543 4871 ELECTRONIC COMPONENTS SURPLUS For broadcast, audiovisual and film industries. Wide bandwidth, high output and unconditional stability with hum-cancelling circuitry, front-panel video gain and cable eq adjustments. 240V AC, 120V AC or 24V DC Frequency Counters,CRO’s, PSU’s, Generators, DVM’s, etc, by HP, Tektronix, Fluke and others. Details at: www.rall.com.au email: rall<at>tpg.com.au RALL ELECTRONICS VGS2 Graphics Splitter High resolution 1in/2out VGA splitter. Comes with 1.5m HQ cable and 12V supply. Custom-length HQ VGA cables also available. Check our NEW website for latest prices and MONTHLY SPECIALS www.questronix.com.au Email: questav<at>questronix.com.au Video Processors, Colour Correctors, Stabilisers, TBC’s, Converters, etc. QUESTRONIX 3990 FULL RANGE $ ELECTROSTATIC Now you can afford the legendary clarity, transparency, depth and precision of an electrostatic speaker. The new Vass ELS-5 is a full range electrostatic speaker, able to faithfully reproduce frequencies from 40Hz-20kHz. • 5 Year Warranty • Wide range of custom finishes. • Individually hand built & tested. 1/42-44 Garden Bvde, Dingley 3172 Pyramid subwoofer Ph 03 9558 0970 Fax 03 9558 0082 separately available email: vass<at>hotkey.net.au All mail: PO Box 548, Wahroonga NSW 2076 Ph (02) 9477 3596 Fax (02) 9477 3681 Visitors by appointment only Do you want YOUR product or service showcased to Australasia's most important electronics marketplace? CALL ME: RICK WINKLER on (02) 9979 5644 and let me explain how cost effective the SILICON CHIP ELECTRONICS SHOWCASE can be for YOU! MicroZed Computers GENUINE STAMP PRODUCTS FROM Scott Edwards Electronics microEngineering Labs & others Easy to learn, easy to use, sophisticated CPU based controllers & peripherals. PO Box 634, ARMIDALE 2350 (296 Cook’s Rd) Ph (02) 6772 2777 – may time out to Mobile 0409 036 775 Fax (02) 6772 8987 http://www.microzed.com.au Most Credit Cards OK New semis from Linear Technology REC Electronics (02 9638 1888; www.rec.com.au) have added a number of new Linear Technology semiconductors, to their range: • LTC1606 – 16-bit 250ks/s analog-digital converter which converts ±10V signals from a single 5V rail • LTC1757 – said to be the smallest, most accurate RF power amplifier controller for single and dual-band GSM/PCS cellular phones • LTC2424/2428 – 4 and 8 channel 20-bit A-D converters with single-cycle settling. • LTC1668 – 50Ms/s 16-bit DAC with 87dB spurious free dynamic range and ±1.5LSB DNL. • LTC1662 – dual 10-bit rail-to-rail voltage output DAC with only 1.5uA supply current • LTC1771 – high efficiency stepdown DC/DC controller with 10uA quiescent current and 90% efficiency 1mA to 1A+. • LTC 1706-81/82 – 5-bit voltage programmer ICs to digitally set the output SC voltage of DC/DC converters. JUNE 2000 37 SERVICEMAN'S LOG We’ve still got our jobs It’s interesting to look back over the last 25 years to see how the different designs of TV sets and video recorders have fared with age. In particular, it’s interesting to note which designs really survived. When the first batch of imported colour TV sets hit the Australian market in March 1975, there was fierce competition between the local brands (HMV, Healing, Pye, Philips, Kriesler) and those from the UK and Japan. Indeed, there was a huge shake up as one outsider, Rank Arena (a UK/Japanese consortium), offered a modified NEC NTSC chassis which made major inroads into the established market. In addition, many new brands were either fully imported or assembled from kits in brand new factories. There was also a lot of rebadging. National started with its M4 series which had plug-in mod u les and 38 Silicon Chip was built in Penrith. Sharp had an 18-inch model which was a monster to repair, while General produced a highly success ful 14-inch portable before moving into larger models later on. Hitachi and Sony also started off with good portables. Most of the Japanese-derived sets were modified NTSC sets and were built like battleships. Some of these sets are still working now, 25 years later. The locally-designed and built sets were based on European designs which, although highly successful in their countries of origin, were not so successful here – despite being significantly upgraded for Australian standards. AWA/Thorn started with a modified 3K5 chassis from the UK. In the UK, they produced millions of these but out here they weren’t as reliable as their Japanese counterparts. When AWA/Thorn subsequently started their Mitsubishi-designed G and K chassis, I well remember a service technician meeting at which the Mitsubishi Service Manager began by stating “Well, Gentlemen, you will all soon be out of a job”! He was wrong, of course, but from simple monochrome sets that broke down up to three times a year, we have progressed to sets that we consider poor if they break down once in three years. However, the quality of soldering is as bad today as it was then and faulty joints are still very common. Yet, in the computer industry, they are almost unheard of – no doubt due to the widespread use of plated-though holes on the PC boards. The early video recorders used piano key controls and came with a multiplicity of belts, tyres and rollers. As a result, they required a belt kit replacement every few years. Nowadays, everything is microprocessor controlled but the decks use flimsy plastic gears. Many faults these days are due to customer abuse, to which a lot of modern equipment is much less tolerant. Those technicians who work with only one brand become very quick at fixing them but often they miss the bigger picture. By contrast, technicians who work on many brands are able to appreciate why some circuits are more reliable than others and often substitute more rugged components or make other modifications to troublesome circuits. Modifications are also issued by the manufacturers but fitting them to a set that is, say, over five years old is often unnecessary (unless safety is involved). After all, if the set has lasted that long, the original circuit could not have been all that bad. Alternatively, there have been cases where the manufacturer has produced modifications only to change them again and again. NEC did this with the earlier series of Daewoo TV chassis, eventually issuing a chart of modifications appropriate for a range of serial numbers within the same model series. Akai is very responsive to problems in their equipment and their service agents are sent copies of service bulletins on all their products. For example, in the SX series video recorders, from the late 80s/early 90s, they were quick to pick up a problem with the fluorescent displays going dark or failing altogether. This was due to the failure of two electrolytic capacitors in the DC-to-DC converter which supplied a -35V rail. Akai VS765 VCR I had such a case recently involving Fig.1: part of the DC-DC converter which supplies a -35V rail and a 4V rail in the Akai VS765 VCR. Transformer L404 is on the left and L405 to its right. one of the SX series, an Akai VS765. Mrs Brady had brought it in with the classic no display fault. The voltages on the fluoro segments were very low, with the normal -35V supply from plug WP1-1 down to about half its correct value. Replacing the usual culprits – C446 and C447 – with 100µF 25V capacitors restored the voltage but not the display. When I measured the display’s filaments, I found that there was continuity but no 4V across them. Once again, it was back to the weird little DC-DC converter Akai is so fond of. I checked D416 and D417 and also the secondary track for cracks but everything looked OK. By this stage, I was rather puzzled as it was hard to understand why the -35V rail was OK but not the 4V rail. I subsequently wasted a lot of time chasing red herrings, such as replacing D416 and D417 with RB-100AT types and fitting a 2.2Ω 0.5W resistor in series with C447. I also wasted a lot of time checking all the other supply rails and the fluorescent display itself out of circuit, but was getting nowhere. In desperation, I started pulling out each component, testing it and Sets Covered This Month • • • • • Akai VS765 VCR. Toshiba Bazooka Model 3408H 80cm TV set. Teac MV1480MkII TV/VCR. Panasonic NV-HD100A VCR. Sharp VC-H85X Hifi VCR. replacing it. As always, these parts are the most difficult to reach and I confess that I acquired a lot of pleas ure from cutting out a piece of plastic from the main case underneath the bottom cover (where it wouldn’t be noticed) to provide better access to the PC board. Finally, my agony was over when I removed transformer L404 and found that its primary was open circuit – due to corrosion from our favourite brown goo inside the can. The reason I couldn’t measure it previously in circuit was because L405, a 1.8mH choke, is in parallel with it, masking the fault. A new transformer restored the fluorescent display and my sanity. Good news & bad The Strathfields had good news and bad news. The bad news was that they had an 80cm Toshiba TV set that needed fixing. The good news was that it was a height/linearity problem, a fault that I’m quite familiar with. More specifically, there are two bright ly coloured 2.2µF electros that spill their insides in many Toshiba sets and cause this problem. This job entailed a house call to attend the Toshiba monster, appropriately called the “Bazooka” (no kidding) Model No. 3408H. I didn’t have a service manual but I felt that this would be in the bag within half an hour. Silly me! The set was sensibly placed in a large rumpus room with good access and lighting. I switched it on and confirmed the fault. I had brought along a small army of electrolytic capacitors because some models use JUNE 2000 39 Serviceman’s Log – continued C372 (0.47µF). The latter in particular was leaky but this didn’t completely fix the problem though it was a lot better and even Mrs Strathfield, who was watching, was impressed. As I was replacing the two previous capacitors, I noticed a 2.2µF electrolytic, underneath the IC, on the copper side of the board, between pins 3 and 15. This had apparently been changed during production at the factory from its drilled and punched position, marked C372, to where it was now. When I removed it, I also noticed that its insides had spilt onto one of the copper tracks and corroded it. Cleaning it all up, repairing the corroded copper and replacing this capacitor finally fixed the fault. Naturally, I was relieved that I managed to get that problem sorted out in situ, as no doubt was Mrs Strathfield. At the same time, due to the intermittent nature of the original fault, I was concerned that it might recur in the weeks and months to follow. Fortunately it didn’t bounce and while going through my Toshiba service manuals back at the workshop, I found a circuit for similar models (3418DA/2529SM) which confirmed that I had done the right thing. Teac TV/VCR different values. Everything was looking good, although the chassis was unfa miliar compared with anything I had seen before. Now all I had to do was find the two culprits which should be designated C303 (1µF) and C317 (2.2µF) in small but different coloured heatshrink plastic cases. The former should be near pin 31 of the large 64-pin jungle IC (IC501, TA8659N). The latter should be near the vertical output stage (pin 2 of IC303, AN5521). I found C317 fairly quickly, although its heatshrink colour was dark brown or black, which doesn’t stand out as well as in previous models. Anyway, I was half-way there. All I had to do was find C303 and replace it but this was where I came unstuck. Though IC501 was a 64-pin jungle IC, it was now a TA8783N and pin 31 was not connected! Furthermore, an extra 16-pin IC, designated IC371 40 Silicon Chip (TA-8739P), had been added and I had no idea what this device was for! It was also about this time that I was informed that the fault was intermittent; that after it had been on for about 10 minutes it would often come good and stay like that. This was not good news because how would I know when it was fixed if it was intermittent? By now I was becoming increasingly pessimistic that I could fix this one on the spot. My guess was that Toshiba, in its wisdom, had scrubbed the pin 31 function of IC502 and substituted IC371 instead, as part of and parcel of some new system. I fished out the freezer and started hitting the small electros around IC371. Fortunately, I was rewarded immediately by all sorts of vertical deflection activity, which suggested that I might be on the right track. I found and replaced C374 (120µF 25V) and My next story involves a Teac MV1480MkII TV/VCR combination that arrived by courier with no note – not even a name and address and certainly no fault marked. I waited a day or so to see if its owner would contact me but no one did. Anyway, when I had a moment I put it up on the bench and switched it on. The set came on for a few moments and then switched itself off (I could hear the click from the relay). However, while the set was on, the picture and sound were both good. I removed the back and the first thing to catch my eye was the sheer volume of dust on the inside. After blowing it all out with the compressor, I located the mains input and relay on a sub board, on the lefthand side looking from the rear. Fortunately, I did have a service manual and I established that the relay switched the AC power to the TV monitor section of the set. I also established that there was no feedback from the separate self-contained TV PC board that might contain some sort of safety circuit, nor was any part of it used to power the VCR or relay circuits. So I wasn’t looking for a fault in the TV set but rather in the relay circuit or possibly the VCR. The relay was controlled by two transistors, which required two conditions to be met for it to switch on. First, the power switch had to tell the VCR main microprocessor to switch on the relay. Second, the 12V rail had to be there. Both these condi tions were being met for a short while but measurements soon indicated that both disappeared simultaneously after about 30-60 seconds. For a while, I suspected that the two transistors might be faulty and spent some time checking them. However, this seemed unlikely, as the set switched on and off repeatedly in exactly the same manner which told me that something else was instructing the microprocessor to turn the set off. This wasn’t good news – access to the microprocessor is quite difficult and involves removing the Funai VCR deck and all its boards. I was about to do this when I noticed that a videocassette was still inside the machine, so I tried to eject it. However, despite actually making a lot of promising noises, it was unable to perform any function before the set switched off. I really needed the tape out before I could disassemble the machine, so I wound the cassette carriage ejector pulley by hand until it was out. I wasn’t sure what the loading motor would do now – after all, the carriage was now up but the mode select switch would remember it as being down. In view of this, I decided to power up the set to see what would happen. I reasoned that it would be best to deal with any loading logic problems immediately, before things got out of hand. Fortunately, the VCR only gave a few whirring sounds from its gears before settling down and stopping. There was hardly any major movement. The interesting thing was that the set now stayed on and was still on five minutes later. Being rash, I decided to tease the VCR gods by re-inserting the same tape and seeing if I could recreate the fault. But I couldn’t make it misbehave – the set stayed on and the tape played flawlessly. So what actually happened? Well, it’s one of those boring old stories I rarely write about – the belts were old and worn and prone to slipping. The mechanism had jammed in noman’s-land and the microprocessor had switched the set off – elementary, my dear Watson. Strangely, the owner still hasn’t phoned but I’m quoting for a new belt kit and a couple of hours work. Panasonic VCR Some time ago, I reported on a Panasonic NV-HD100A VCR that had noise on standard playback (SP) but was OK on long play (LP). I cleaned the heads but that made no difference and finally diagnosed, located and repaired a hairline fracture in the solder on pins 1, 2 and 3 of plug P502 of the head amplifier. I discovered this by wobbling the head amplifier in situ until the picture came good. Resoldering the joints appeared to fix the problem because I left it on soak test for days before the client picked it up and everything was perfect. I didn’t think any more about it until just over three months later, when the owner phoned to complain that it was doing the same thing again. It was the same old routine emotive story that I’ve heard many times – the fault was exactly same and they had hardly used it, etc, etc. So why did they wait until it was out of warranty to report it? I didn’t press the point and as my policy is to always give the customer the benefit of the doubt, I told them to return the set and I would check it out. They came in the next day and I checked it out in front of them, fully expecting it to be some other symptom that they were not astute enough to identify. My arrogance was quickly crushed when I discovered that it was indeed exactly the same fault as before. Just in case, I removed the covers and cleaned the heads and it was still crook. I then wiggled the head amplifier and the fault came good. Well, these people had a point; I would have to investigate further and they would have to leave it with me. How could a resoldered faulty joint or fracture break again? It definitely wasn’t possible and there had to be some other explanation. I took the head amplifier out of the K chassis mechanism/deck and examined it more carefully under a magnifying lamp. I was pleased to see that there were definitely no more P.C.B. Makers ! • • • • • • • • • If you need: P.C.B. High Speed Drill P.C.B. Guillotine P.C.B. Material – Negative or Positive acting Light Box – Single or Double Sided – Large or Small Etch Tank – Bubble or Circulating – Large or Small U.V. Sensitive film for Negatives Electronic Components and Equipment for TAFEs, Colleges and Schools FREE ADVICE ON ANY OF OUR PRODUCTS FROM DEDICATED PEOPLE WITH HANDS-ON EXPERIENCE Prompt and Economical Delivery KALEX 40 Wallis Ave E. Ivanhoe 3079 Ph (03) 9497 3422 FAX (03) 9499 2381 • ALL MAJOR CREDIT CARDS ACCEPTED Silicon Chip Binders REAL VALUE AT $12.95 PLUS P&P  Heavy board covers with 2-tone green vinyl covering  Each binder holds up to 14 issues  SILICON CHIP logo printed on spine & cover Price: $A12.95 plus $A5 p&p each (Australia only) Just fill in & mail the handy order form in this issue; or fax (02) 9979 6503; or ring (02) 9979 5644 & quote your credit card number. JUNE 2000 41 Serviceman’s Log – continued were not only faulty but had the same fault. Because of this, he felt that he should get a discount for bulk repairs but I felt the opposite. In the end, we agreed that we would wait until I had diagnosed the fault(s). He described the sets as “dead and whistling”. The first one I looked at was doing precisely that and the whistling was coming from the switchmode power supply cage on the righthand side. Removing the power supply from the rest of the VCR was difficult as it is hard to get it past the top PC board. Eventually, my persistence paid off and I finally got it onto the bench and removed its covers. The main suspect suspect joints but where to from here? The head amplifier plugs into the lower head drum assembly PC board, which carries the static coils of the rotary transformer. I hoped these weren’t open circuit – being a hifi VCR, their cost would exceed the price of a new VCR. How would I explain that? Next, I removed the entire cylinder (upper and lower assembly), after first removing the antistatic wiper and auto head cleaner on the top. There are only three screws underneath to release the mechanism, plus the plugs and sockets. With the assembly upside down on the bench and with its cover removed, I could now clearly see a row of suspect joints, especially along the plug sockets. In fact, the entire board was poorly soldered and even the rotary transformer winding termina tions looked crook. I reworked the entire board very carefully, then reassembled and tested the deck. Once again everything was working properly and after soak testing it, I returned the set to its owners at no charge. That’s not all I thought that that would be the end of this saga but they were back on the phone just six weeks later. As before, they trotted out the familiar routine, complaining that it was exactly the 42 Silicon Chip same fault as before, that the set had never been right, etc, etc. I cut them off at the pass by telling them that if they brought it in, I would look at it straight away. Surely lightning couldn’t strike twice at the same spot, I thought. They were around in the blink of an eye and although they were icily polite, I sensed that something was different. When I tested the machine, it turned out that the tape was jamming inside. So much for their complaint that it was “doing the same thing as before”. I removed the cover and there, staring right back at all of us, was a cassette label stuck over the idler in the centre at the bottom of cassette carriage. I pulled it out with a pair of pliers and, without comment, passed it to the more vocal of the pair. I then connected the VCR to a TV set, put in a cassette, made a recording and played it back right in front of them. Bashfully, they took their machine and, with tails between their legs, made for the exit. As a PS to this story, I have had similar faulty joint experiences with this type of failure on two subsequent K chassis Panasonic VCRs, so this may be a common problem. Sharp hifi VCR Mr Andriotti has no less than two Sharp VC-H85X hifi VCRs and both It didn’t take long to identify a leaky 47µF 16V electrolytic (C913) as the main suspect. Refitting the power supply into the VCR took longer than replacing the capacitor but eventually it was back in and the set returned to life. I checked all the functions and everything worked OK, except that rewind was slow towards the end. I put this down to belts and decided that they should be replaced, subject to haggling with Mr Andriotti. I reached for the next VCR and plugged it in but it burst into life immediately. I decided to look at the power supply anyway and C913 was even more leaky that its sister in the first machine. I replaced it but when it came to checking the set’s functions, it was worse than the previous one. I removed the base cover to check the state of the reel idler belt and discovered that it was worn. In addition, the capstan motor plastic pulley was cracked and slipping. Armed with these facts, I sought out Mr Andriotti and after some light banter, we settled on an amicable deal which involved changing the belts and tyres and gluing the pulley. As it happened, when I checked the first VCR, the same plastic pulley was also cracked. By the way, I am fairly certain that this pulley is now available as a spare part, although it is not in the service manual except as part of the capstan motor assembly. It’s possible that the replacement is similar to the Mit subishi one – a brass pulley which costs an arm and a leg. Gluing it seemed to be the cheapest SC way. CIRCUIT NOTEBOOK Adding LED indication to 12V trickle charger LED1 is connected in series with the base of Q3 and it is fully alight when the battery is being charged at high current. As the current reduces, LED1 reduces in brightness but not markedly so. When the battery comes up to full charge at about 13.8V or so, LED2, in series with Q1’s collector, comes on to indicate that the circuit is now in trickle mode. The original 2.2kΩ collector resistor for Q1 has been reduced to 1kΩ to provide a little more current _ through LED1. Even so, LED1 will not glow as brightly as LED2. Also LED2 still glows dimly when the circuit is in trickle mode, to indicate that a small charge current is flowing. This modified version of the 12V trickle charger and a 24V version is now available from Altronics Distributors in Perth. The catalog numbers are K-4225 (12V version) and K-4226 (24V version). Phone 1 800 999 007. SILICON CHIP PLUG IN AND MEASURE NEW 0.47F TO BATTERY + The 12V trickle charger published in the October 1998 issue of SILICON CHIP has the virtue of simplicity in that you can permanently hook it up to a battery and it will keep it in good condition. However, it doesn’t give any indication as to whether it is fully charging or trickling. That problem can be solved with the addition of two high brightness LEDs and a change to one resistor value. We have published the full circuit for convenience. Rs 0.47 5W 100 22F 25VW 1k LED1* CHARGING LED2* FLOAT Q1 BC557 * HIGH BRIGHTNESS RTN introduces the TiePie HANDYPROBE HP2 - 2.2k Q2 BC639 0.22F ~ + _ ~ B1 400V 6A STORAGE OSCILLOSCOPE SPECTRUM ANALYSER VOLTMETER TRANSIENT RECORDER a powerful, 8-bit 20MHz virtual measuring instrument for the PC. Genuine PARALLAX BASIC Stamps PHYTEC Rapid Development Tools ELAB Application Specific Chips BS1, BS2 & the new BS2-SX. OEM chipsets for high volume applications. OZ-made BS Development board for all the BASIC Stamps T1 CASE also available thru Jaycar nationwide (25 convenient locations) RobotOz in WA (08) 9243 4842 EARTH NEUTRAL 240V AC Convince yourself: download the demo software from www.tiepie.nl Other fine products from RTN include: All BASIC Stamps stocked: 15V 15V ACTIVE F1 0.5A SB RTN: S R 20 YEA NCE EXPERIE TRONIC IN ELECTROL CON 2.2k 1.8k 39k Q3 BD139 Q4 2N3055 500mV -- 400V 0 -- 20MHz 8-bit New Serial port driven LCD modules. 2*16 and 2*40 types available. Software control over backlit, etc... FREE CD-ROM catalog now available - includes 85MB of data on our products (03) 9338 3306 email: nollet<at>mail.enternet.com.au http://people.enternet.com.au/~nollet RTN Phone/Fax JUNE 2000 43 +6V 100k 100k .01F 10k 1N4148 3 .01F 1 2 + + - 6 7 100k 100k SPEED CONTROL INPUT VOLTAGE 9 6 2 11 5 10k 7 10 4 10k + + 13 - 14 12 + - 4 1 - IC2 LM358 470 1W D1-D4 4x 1N4001 3 1 5 .01F 150 15V 470F 15V + SCR2 REG1 7806 IN OUT +6V GND 470F 470F EARTH Low-cost logic indicator for PICs +6V IC1 This simINPUT 4069 ple, low cost (PROBE) 14 1 2 circuit was 7 developed to 150 monitor the inputs and outputs of PIC LED1 processors and oth er digital chips. It LED2 uses a 4069 hex inverter with a pair of inverse-parallel connected LEDs between the input and output of each inverter. As the inverter’s output is always the opposite to its input, red LED1 will turn on if the input is low (ie, output is high) and green LED2 if the input is high (ie, output low). The 150Ω resistor limits the current but remember that this current must also flow out of (source) or into (sink) the device output being measured. For a 5V supply the current will be limited to around 20mA. You could also use a bi-colour LED instead of separate LEDs. Craig Rodgers, Camperdown, NSW ($25) 44 Silicon Chip IC3 555 2x C106D1 T1 NEUTRAL 2 IC4 MOC3020 SCR1 240V AC 8 .01F D2 BYV26E 0V=MAX SPEED 6V=MIN SPEED F1 ACTIVE 0.5A SB 6 3 + 4 7 5 .01F 10k IC1 LM339 VR1 10k 8 8 10k 10k VR2 10k TO MOTOR VR1: SET MIN DUTY CYCLE MOTOR CUTOUT VR2: SET MAX DUTY CYCLE ACTIVE NEUTRAL EARTH Speed controller for 240VAC universal (brush-type) motors This circuit was designed to control a coil winder driven by a 240V sewing machine motor. Typically, these universal brush motors are controlled by a half-wave SCR circuit but this circuit uses two inverse parallel connected SCRs to provide full wave control and thereby a wider speed range. A Triac was not used because the motor inductance causes a lagging current which can prevent these devices from turning off reliably at the end of each mains half-cycle. The circuit works as follows: one half of the quad comparator IC1 acts as a zero-crossing detector, with inputs from both sides of the power transformer secondary winding. The outputs of the two comparators concerned are sawtooth waveforms synchronised with each mains half cycle. The other half of the quad comparator compares these sawtooth waveforms with the input DC voltage and the output, at pins 13 & 14 is a series of pulses which triggers IC3, a 555 timer connected as a monostable, via IC2. IC2, a dual op amp, is used in conjunction with trimpots VR1 and VR2 to set the minimum and maximum duty cycle of the pulse train fed to pin 4 of IC3. IC3’s output at pin 3 drives opto-coupler IC4 and this triggers the two inverse connected SCRs. An interesting wrinkle in the circuit is the inclusion of diode D2 in series with the gate drive to the two SCRs. This was needed to prevent erratic triggering at very short (less than 30%) or very long (more than 85%) duty cycles and this appears to give optimum speed control with typical sewing machine motors. The speed is controlled by a DC input variable between 0 and 6V from a potentiometer (not shown) or possibly from a feedback signal derived from a tachometric circuit for automatic speed control. Herman Nacinovich Gulgong, NSW. ($50) SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au VINTAGE RADIO By RODNEY CHAMPNESS, VK3UG A Japanese 110V AC/DC set Japan was exporting valve radios by the late 1950s and early 1960s, although still struggling to recover following its defeat in World War 2. The standard of the exported radios at that time was mediocre and we often looked down our noses at the sets. How times have changed! “They’ll never make radios as good as we do”, was the familiar catch-cry in those days. Famous last words! The Japanese now make some of the best radio equipment in the world and Japanese electronic equipment now fills our living rooms, work places and cars. The big difference back in the 1950s and 1960s was that Japan was then a cheap labour country, so the radios were cheap to import. A friend had a badly damaged JapaBelow: front view of the Japanese 110V AC/DC receiver circa 1960 with hand-drawn dial calibrations and stick-on labelling. nese radio set that was no use to him. Did I want it? “Yes please”, I said. Being an inquisitive fellow, I wanted to see what I could find out about it. Unfortunately, quite a bit of the cabinet had been broken and the back panel, knobs and decorative front panel were missing – hence the stick-on Dymo® labelling and handdrawn dial calibrations shown in the photograph. In fact, one whole end of the cabinet with one loudspeaker was completely broken away (the set uses two 100mm speakers, one at each end of the cabinet. It had obviously fallen and not bounced at all well off the floor! I was interested to see how the receiver would perform as I hadn’t seen this model before. I have no idea what brand the set is though, due to the fact that so many bits are missing and there’s no chassis labelling. I glued the cabinet back together with plumbers blue plastic cement. I don’t recommend it but this was only going to be a rough job to see how a Japanese radio of this era performed. The set was then given the once over and any minor components considered likely to create trouble were replaced. 110/117V AC/DC operation I laboriously traced out the circuit and found that it operates from 110/117V AC/DC (and that means be careful). Well, I got it up and running on both the broadcast and shortwave bands. The shortwave band tunes from 3.8-12MHz and is very much an afterthought, as there is only one adjustment for that band (and minimal adjustments for the broadcast band). Despite the lack of adjustments in the front end, it appears to be well JUNE 2000 53 Rear view of Japanese 110V AC/DC receiver. The 240V-to-110V transformer was fitted at the end of the cabinet near the power lead in. Do not touch AC/DC sets unless you are very experienced and know exactly what you are doing – they can be very dangerous. aligned, with good sensitivity. The manufacturer really did do a good job of getting the prewound coils right, so that few adjustments are needed. With a few more adjustments, the radio would no doubt work even better. The circuit diagram is quite standard, even allowing for the fact that it is an AC/DC set. The valves all use 0.15A heaters and are strung in series across the 110/117V mains. The valve line-up is as follows: 12BE6, 12BD6, 12AV6, 50C5 and 35W4. Note that the first two numbers indicate the voltage of the heater. The 50C5, a 7-pin miniature type, gets extremely hot. Its heater dissipates 7.5W compared to 3W for the 6AQ5/6V6GT and that’s even before the plate and screen dissipation is taken into account. The 50C5 is designed to work quite well with between 110-130V DC on the plate and screen. from the grid to the bottom of the fist IF coil secondary. The 470kΩ potentiometer in the AGC line functioned as a crude volume control. The first audio stage is quite conventional, as is the audio output stage. The main points of interest here are the use of a 50C5 and the unbypassed 160Ω cathode resistor which gives some degeneration. As an aside, some of the audio circuitry is enclosed in a small hybrid block of components. This method of reducing the time to wire sets wasn’t used for long. Instead, radios using PC boards and individual components proved much more popular. The main drawback was that if one component became faulty, it was not always easy to isolate, As a result, the components in the hybrid circuit were usually all replaced and the unit thrown in the rubbish bin. Converter Power supply The converter stage uses the 12BE6. This is a standard pentagrid converter and uses a tapped coil in the cathode for the oscillator. The aerial coil arrangement is also standard but very austere, with few adjustments as mentioned earlier. The intermediate frequency (IF) amplifier is a basic 455kHz system using a 12BD6 which is a 7-pin miniature valve similar to a 6BH5. The 12AV6 is used as the detector stage and this has its two diodes strapped together. The AGC line runs The power supply is the conventional half-wave rectifier system used in AC/DC sets. Incidentally, if the set is used on DC, it is necessary to make sure the above-chassis input lead is positive otherwise the set won’t work (yes, the valves light up but the valves get no high tension (HT) voltage). Because a half-wave rectifier is used, the filter capacitors for the HT rail are larger than normal at 30µF each (all three of them) to reduce the ripple. Any interference on the mains is poorly filtered using just two .01µF 54 Silicon Chip capacitors. The chassis of the set can be earthed as it is not directly connected to either side of the mains. Instead, the “earthy” side of the mains (ie, the Neutral) runs around the chassis as a wire bus and is connected to the chassis via one of the .01µF capacitors. However, this set does have one potential “bitie” and that’s the earth terminal of the phono input which is connected to one side of the mains. Just imagine this braided earth lead going up to the earthed metal work of the turntable! If the active side of the mains was on the “earthy” side of the input (ie, the active and Neutral were transposed), this could be lethal. How manufacturers ever got away with such things is beyond me! This model set was imported into Australia as a 110V receiver. So how was it used here? Well, in Australia, it was converted to 240V AC by fitting a 240V-to-110V power transformer into spare space in the cabinet. It was roughly fitted I might add but at least it made the set safe as far as shocks from the phono earth terminal were concerned. Summary This radio is reasonably typical of the standard of receivers manufactured in Japan at that stage. I had a Lafayette HE-30 receiver of the same general vintage and while it was better than this set, it isn’t all that much better. Japan is now light years ahead of that mediocre standard, as we all know. In summary, this was a rough and ready set but it is stable and works quite satisfactorily. However, I wonder how well it would go in an electrically noisy environment with virtually no noise filtering on the mains input. It’s an interesting little set – part of the history of the era – but it certainly isn’t one of my favourites. Safe servicing AC/DC sets Although AC/DC sets were quite common in America and in Europe, we in Australia and New Zealand have been rather wary of dealing with “hot” chassis sets. However, they were produced in small numbers in Australia and New Zealand to suit some of the small townships that had DC power only but which might be converted to AC later on. These sets were also bought by people who shifted around and could not be sure if the next town they were going to had AC or DC power. Some of the last valve portables also were “hot” chassis sets, having one side of the mains connected to chassis when they were used on mains in lieu of batteries. The first comment to be made in regard to servicing such sets is be careful – exercise extreme caution and double check everything. Do not touch these sets unless you are very experienced and know exactly what you are doing – they can be death traps. Depending on the circumstances, there really isn’t a great deal of difference between grabbing the chassis of a “hot” chassis set and earth at the same time as grabbing 400V DC HT in a receiver and chassis earth. The effects can be identical – death. So be careful with all receivers. They can be lethal if you are careless. With an AC/DC set, first check which pin of the mains plug goes to chassis or, if it is a better designed set, to the negative bus that is insulated from the chassis. Make absolutely sure that it is the Neutral that goes to the bus or to the chassis. Also, check the capacitor that goes between the chassis and the negative bus in the receiver. This should have a rating of 250V AC working and must be in good order (in fact, it’s probably best to replace it, just to make sure). However, never assume that the chassis will be at Neutral potential when plugged into just any power point. If the power point is wired incorrectly (eg, Active and Neutral transposed), the chassis could be live (and that includes the pot shafts)! Additionally, even if you are quite sure that the set is wired in a safe manner, use a rubber mat to stand on and don’t touch any parts, including the chassis, while the set is on (the chassis will only be safe to touch if it is actually connected to mains Earth). Many people use a 240V-to-240V isolation transformer to be even more certain. A core balance detector such as recommended in Vintage Radio for May 1998 is cheap insurance. One thing that cannot be done is to run the set with a valve missing. That’s because the valve heaters are wired in series and if one valve is out of the set, all the heaters go out. This means that it isn’t possible to test the output stage with the other valves removed as can easily be done with receivers using parallel wired heaters. Another problem is wiring in dial lamps (this set has none). They cannot simply be wired in series with the heaters, as these have low resistance at switch on (ie, when cold) and draw a heavy current. If you did connect them in this manner, the dial lamps would light up brightly – for a few seconds – and then expire. So how did the set manufacturers overcome this problem? In the case of the radio featured here, a dial lamp could be wired between pins 4 and 6 of the 35W4 valve. The voltage drop across this portion of the 35W4 heater will be nominally correct for a 6-8V 150mA dial lamp. Note however that the socket would need to be well insulated to ensure there were no shorts or shocks, as both sides of the socket would be at virtually full mains voltage above the chassis or negative bus. High-voltage valves In Australia, we did not have the range of high-voltage valves that were available in America and Europe. As a result, although the valve heaters were wired in series, the voltage drop across them was much less than 240V. Resistors wired in series with the heaters accounted for the rest of the voltage drop and often, in a higher quality set, a barreter or current regulator would be used as well. A barreter consisted of an iron-wire resistor mounted in a glass bulb containing hydrogen. This device gave a constant current for a wide range of applied voltages. For example the 161 has a constant ELECTRONIC VALVE & TUBE COMPANY The Electronic Valve & Tube Company (EVATCO) stocks a large range of valves for vintage radio, amateur radio, industrial and small transmitting use. Major current brands such as SOV-TEK and SVETLANA are always stocked and we can supply some rare NOS (New - Old stock) brands such as Mullard, Telefunken, RCA and Philips. Hard to get high-voltage electrolytic capacitors and valve sockets are also available together with a wide range of books covering valve specifications, design and/or modification of valve audio amplifiers. PO Box 487 Drysdale, Victoria 3222. Tel: (03) 5257 2297; Fax: (03) 5257 1773 Mob: 0417 143 167; email: evatco<at>mira.net New premises at: 76 Bluff Road, St Leonards, Vic 3223 current of 0.16A through it for applied voltages of 100-200V. This was handy, as it meant that the huge inrush current through cold heaters was avoided and dial lamps could be wired in series with the mains (provided a 6.3V dial lamp had less than 6.3V across it to ensure long life). Additionally, there was no need for a voltage tapping for different voltages between 200V and 250V - the current regulator took care of all of this. A 240V set using 0.15A heaters required about 36W for the heaters and series resistors. The HT circuit probably required a further 12-15W, making a total of about 50W - typical of even AC-operated receivers of that particular era. However, for some strange reason, a few manufacturers used 0.3A heaters, which meant that the heater and series resistors used 72W before any HT current was taken into account. These would have been cosy sets to operate in the middle of winter, as the inside of the case really did get quite hot. By contrast, the receiver described in this article only used about 22W SC from a 110-117V mains supply. JUNE 2000 55 Li’l PowerHouse A new 40V/1A switchmode power supply with LCD readout Is your old power supply so old it has germanium transistors? Maybe it has Dymo® labels on the front panel and a fabric-covered power cord? Er, does it use a copper oxide rectifier? If you have an ancient power supply, now is the time to give it the heave-ho and get this up to the minute design. By PETER SMITH & LEO SIMPSON 56 Silicon Chip T HIS NEW POWER SUPPLY has a big power output for its size. It can give DC voltages up to 40V and the output current can be as much as 1.2A, depending on the voltage setting. And it can be varied right down to less than 1.5V while still giving out 1.2A. This is great for testing battery circuits that operate at 1.5V, 3V or whatever. In times past when we have looked at doing a compact power supply, the natural approach would be to produce an analog design with an analog meter on the front panel. An example of this was our dual tracking 18.5V supply published in the January 1988 issue. The analog approach has the virtue of simplicity and it gives good results. But that’s in the past. And it is boring. Nowadays we can do a lot better with a switchmode design. It is more efficient so big heatsinks are unnecessary and you can get a higher maximum DC voltage output for a given secondary voltage from the power transformer. And you can get a lower minimum DC voltage at full current with having problems with the high power dissipation of a conventional series regulator. In fact, this circuit will have losses of less than 10W (including transformer losses) under worst case conditions, meaning that it does not need any heatsink apart from that provided by the back panel of the case. By contrast, if we had gone to a conventional regulator using the same power transformer, it would have losses (ie, heat) of around 30W when delivering 1.5V at 1.2A and it would need a fairly substantial finned heatsink on the rear of the case. Another good feature of the design is the low level of ripple and hash in the output, and this is not always the case with switchmode designs. We have achieved this with critical attention to the circuit layout and two stages of LC filtering. Digital panel meter The new supply has a 3.5-digit LCD panel to monitor the voltage or current, as selected by a toggle switch. As well, you can set the current limit by pressing a button on the front panel and then rotating the knob closest to the LCD panel. A 10-turn potentiometer lets you precisely set the output voltage which can be done before you connect the output load by means of the load switch. In addition, there is a LED on the front panel, just next to the “set current” knob, to indicate when an overload occurs. The supply is protected against short circuits by the way. The voltage vs current characteristic is shown in the graph of Fig.1. As it shows, the supply will deliver 1.2A over the range from less than 1.5V to 30V. At higher voltages, the available current drops off because the transformer is only rated at 30VA which means that it could only deliver 1A at 30V if the circuit had no losses at all. In fact, we are over-rating the transformer to get 1.2A at 30V but it Fig.1: the voltage vs current characteristic of the supply. It is capable of delivering 1.2A over the range from 1.23V to 30V. Beyond that, the current falls off due to the transformer regulation. quite good too. In fact, apart from the output noise and ripple, the perfor mance is actually a little better than our previous 40V 3A power supply published in the January & February 1994 issues. Based on switcher Fig.2: how a switching regulator operates. When S1 is closed and S2 is open, current flows to the load via L1 which stores energy. When S1 opens and S2 closes, the energy stored in L1 maintains the current through the load until the switches toggle again. does not appear to be a problem – the transformer appears to be conservatively rated at 30VA. At 40V, the output current from the prototype supply was around 160mA which is pretty respectable for a small supply. As shown in the specifications panel, the load regulation of the circuit is excellent and the line regulation is The circuit is based on the National Semiconductor LM2575HVT high voltage adjustable switchmode voltage regulator. This is almost identical to the switcher chip used in the 40V/3A power supply mentioned above. However, this new 40V/1A circuit is not simply a cut-down version of the 1994 design; apart from the use of the switcher chip, it is different in a number of aspects. Let’s have a brief look at how the switcher works. Fig.2 shows how a switching regulator operates. In operation, S1 and S2 operate at high speed and are alternately closed and opened. These two switches control the current flowing in inductor L1. When S1 is closed and S2 is open, the Main Features • • • • • • • • • • • Output voltage continuously variable from 1.23V to 40V Output current of 1.2A from 1.23V to 30V LCD panel meter for voltage & current 10-turn pot for precise voltage adjustment (optional) Adjustable current limit LED current overload indication Output fully floating with respect to mains earth Load switch Low output ripple Short circuit and thermal overload protection Minimal heatsinking JUNE 2000 57 Fig.3: a basic regulator using the LM2575 switcher IC. In this circuit, a switching transistor takes the place of S1 in Fig.1 and diode D1 takes the place of S2. The output voltage is set by the ratio of R2 & R1 which feed a sample of the output voltage back to an internal comparator. current flows to the load via inductor L1 which stores up energy. When S1 subsequently opens and S2 closes, the energy stored in the inductor maintains the load current until S1 closes again. The output voltage is set by adjusting the switch duty cycle – the longer S1 is closed and the current flows through it, the higher will be the output voltage. Fig.3 shows a complete voltage regulator based on the LM2575 IC. It is a 5-pin device which requires just five extra components to produce a basic working circuit. Its mode of operation is the same as that described in Fig.2 except that here an internal switching transistor is used for S1, while an external diode (D1) is used for S2. What happens in this case is that when the transistor is on, the current flows to the load via inductor L1 as before and diode D1 is reverse-biased. When the transistor subsequently turns off, the input to the inductor swings negative (ie, below ground). D1 is now forward-biased and so the current now flows via L1, through the load and back through D1. The output voltage is set by the ratio of R2 and R1 which form a voltage divider across the output (Vout). The sampled voltage from the divider is fed to pin 4 of the switcher IC and then to an internal comparator where it is compared with a 1.23V reference. This sets Vout so that the voltage produced by the divider is the same as the reference voltage (ie, 1.23V). Apart from the comparator and the switching transistor, the regulator IC Specifications Minimum no load output voltage........................................................ 1.23V Maximum no load output voltage.......................................................... 40V Output current............................................................................... see Fig.1 Current limit range.................................................................. 10mA to 1.2A Current limit resolution........................................................................10mA Line regulation..............................0.1% for a 10% change in mains voltage Voltmeter resolution..........................................................................100mV Current meter resolution.......................................................................1mA Meter accuracy......................................................................2% plus 1 digit Load regulation no load to 1A <at> 24V.......................................................................1.2% no load to 1A <at> 12V.......................................................................1.5% no load to 1A <at> 6V.........................................................................1.8% no load to 1A <at> 3V.........................................................................3.3% Output noise and ripple 3V to 24V <at> 1A............................................................ 25mV p-p (max) 58 Silicon Chip also contains an oscillator, a reset circuit, an on/off circuit and a driver stage with thermal shutdown and current limiting circuitry. The incoming supply rail is applied to pin 1 of the IC and connects to the collector of the internal switching transistor. It also supplies an internal regulator stage for the rest of the regulator circuit. In essence, the LM2575 uses pulse width modulation (PWM) to set the output voltage. If the output voltage rises above the preset level, the duty cycle from the driver stage decreases and throttles back the switching transistor to bring the output voltage back to the correct level. Conversely, if the output voltage falls, the duty cycle is increased and the switching transistor conducts for longer periods. The internal oscillator operates at 52kHz ±10% and this sets the switching frequency. In theory, this frequency is well beyond the limit of audibility but in practice, a faint ticking noise may be audible due to magnetostrictive effects in the cores of the external inductors. One very useful feature of the LM2575 is the On/Off control input at pin 5. This allows the regulator to be switched on or off using an external voltage signal and we have used this to provide the adjustable current limiting feature, as we shall see later on. Circuit details Fig.4 shows the full circuit of the new power supply. Transformer T1 is supplied with mains power via fuse F1 and power switch S1. Its 30VAC secondary is JUNE 2000 59 2000 10F 16VW +5.1V C- 1 5 -5.1V 10F 16VW LED A K -5.1V -5.1V 4 x 0.1F GND 3 LM2575 4 IC5 ICL7660 8 V+ 2 5 C+ OUT 0V 30V D1-D4 1N4002 100 100 2 3 4 VR3 10k 6 1 4 100k 100k 1 2 1 OUT 1k 100k 2 2 1 6 5 2 3 5 METER ZERO VR5 100k 1 4 IC4 TL071 7 +5.1V -5.1V 6 S4: 1 - MEASURE CURRENT 2 - SET CURRENT 1M 100k 100k 1M 330pF 5 8 7 2 300 RFH 9 10 ROH 11 DP3 .8.8.8 6 1M 27k VOLTS CAL VR4 5k 0.1F 63VW 13 2 1 V- V+ S3b 2 1 + EARTH _ OUTPUT 1.23-40V 1A +5.1V CASE 0.1F 250VAC 0.33F 63VW LOAD S2 DP1 Q0570 DIGITAL PANEL METER 1 INLO COM RFL INHI 4 IC3b LM393 470 8 2 x 47F 63VW + LM336-2.5 REF1 _ D6 1N4148 3 *SEE TEXT *R1 0.005 L2 47H OVERLOAD LED1 3 x 470F 63VW 1k S3: 1 - MONITOR CURRENT 2 - MONITOR VOLTAGE 7 4.7k 680 5W L1 470H D5 MBR360 IC3a LM393 +2.5V +5.1V 5 100k S4a 2 S3a 3 FB ON/ GND OFF IN IC1 LM2575HVT-ADJ CURRENT LIMIT VR2 1k S4b OP77GP 0.1F 1.5k CURRENT CAL -5.1V IC2 7 330F 63VW 15k 2 x 2200F 50VW VOLTAGE ADJUST VR1 50k 40V/1A ADJUSTABLE POWER SUPPLY _ + ADJ LM336Z 10F 16VW +5.1V 100F 16VW ZD1 5.1V 1W 1k 5W CASE POWER S1 250VAC T1 M6672L Fig.4: the circuit is based on IC1, the LM2575 switcher controller. It runs at around 50kHz and the resultant DC output is filtered with inductors L1, L2 and the associated capacitors. IC2 & IC3 provide the current limit feature while IC4 drives the LCD panel meter. SC E N 240VAC A F1 500mA Parts List 1 PC board, code 04106001, 171 x 127mm 1 M6672L 30V 30VA mains transformer 1 DPDT 250VAC 6A plastic rocker switch with neon indicator (S1) 2 S1345 DPDT miniature toggle switches (S2,S3) 1 DPDT momentary pushbutton switch (S4) 1 LCD panel meter (Altronics Q-0570) 1 M205 panel-mount safety fuse-holder (F1) 1 500mA M205 fuse 1 470µH toroid inductor (L1) 1 47µH toroid inductor (L2) 1 TO-220 insulating bush and washer 2 15mm knobs 3 captive binding post terminals (1 red, 1 green, 1 black) 1 cordgrip grommet for mains cable 1 13-way 2.54mm SIL header plug (for connection to panel meter) 4 3.2mm solder lugs 22 PC stakes Hardware for pre-punched metal case 1 pre-punched metal case 3 M4 x 10mm screws 4 M4 nuts 2 M4 internal star washers 8 M3 x 6mm screws 1 M3 nut 1 M3 flat washers 4 10mm tapped spacers Hardware for plastic instrument case 1 plastic case, 200 x 155 x 65 mm (W x D x H) with metal front and rear panels (Altronics Cat. H-0481F & H0484F) 2 M3 x 10mm screws 1 M3 x 15mm countersunk screw 5 M3 nuts 1 M3 flat washer 4 M3 internal star washers 2 M4 x 10mm screws 2 M4 nuts 2 M4 flat washers 4 self-tapping screws (to mount PC board) Semiconductors 4 1N4002 1A 100V diodes (D1-D4) 60 Silicon Chip 1 MBR360 3A Schottky diode (D5) (SR306 or 31DQ06 also suitable) 1 1N4148 small signal diode (D6) 1 LM2575HVT-ADJ high voltage switchmode controller (IC1) 1 OP77GP op amp (IC2) 1 LM393 dual comparator (IC3) 1 TL071 op amp (IC4) 1 ICL7660 switched capacitor voltage inverter (IC5) 1 LM336Z-2.5 voltage reference (REF1) 1 1N4733 5.1V 1W zener diode (ZD1) 1 3mm red LED with bezel (LED1) Resistors (0.25W, 1%) 3 1MΩ 2 1kΩ 6 100kΩ 1 1kΩ 5W 1 27kΩ 1 680Ω 5W 1 15kΩ 1 470Ω 1 4.7kΩ 1 300Ω 1 1.5kΩ 2 100Ω Potentiometers 1 50kΩ 16mm linear pot (VR1) OR 1 50kΩ multi-turn linear pot 1 1kΩ 16mm linear pot (VR2) 1 10kΩ horizontal trimpot (VR3) 1 5kΩ horizontal trimpot (VR4) 1 100kΩ horizontal trimpot (VR5) Capacitors 2 2200µF 50VW PC electrolytic 3 470µF 63VW PC electrolytic 1 330µF 63VW PC electrolytic 1 100µF 16VW PC electrolytic 2 47µF 63VW PC electrolytic 3 10µF 16VW PC electrolytic 1 0.33µF 63VW MKT polyester 6 0.1µF 63VW MKT polyester 1 0.1µF 250VAC MKT polyester 1 330pF MKT polyester Wire and cable 1 2-metre 250VAC mains lead with 3-pin plug 1 600mm length of green/yellow mains wire 1 200mm length of 13 way ribbon cable 1 60mm length of 0.4mm enamelled copper wire Miscellaneous Cable ties, heatshrink tubing, heatsink compound, solder, hook-up wire. full-wave rectified using diodes D1D4 and filtered using two paralleled 2200µF 50VW elec trolytic capacitors. The resulting 42V DC supply is applied to the switching regulator (IC1). The additional 330µF capacitor connected between pins 1 & 3 of IC1 is included to prevent circuit instability and is mounted as close to the IC as possible. Diode D5, inductor L1, the three 470µF capacitors and potentiometer VR1 form the basic switchmode power supply block (see Fig.4). D5 is a 3A Schottky diode which has been specified instead of a conventional fast recovery diode because of its low forward voltage drop. As a result, there is very little heat dissipation within the diode and this leads to increased efficiency. The output from IC1 feeds directly into L1, a 470µH induc tor. The 10-turn potentiometer VR1 and its associated 1.5kΩ resistor provide voltage feedback to pin 4 of IC1, to set the output level. When VR1’s resistance is at 0Ω, the output from the regulator (pin 2) is equal to 1.23V. This output voltage increases as the resistance of VR1 is increased. The 680Ω 5W resistor connected across the regulator output discharges the three 470µF capacitors to the required level when a lower output voltage is selected. 2nd filter circuit Inductor L2 and its associated 47µF and 0.1µF capacitors provide a second stage of filtering to further attenuate the switching frequency ripple. The resulting filtered voltage is then applied to the output terminals via load switch S2. Additional filtering is applied at this point using a 0.33µF capacitor across the terminals and a 0.1µF capacitor between the negative terminal and the case. Current limiting The current sense resistor (R1) is wired into the negative supply rail adjacent to inductor L2 and consists of a short length of 0.4mm enamelled copper wire. The voltage developed across it is multiplied by 200 using op amp IC2, so that IC2’s output delivers 1V per amp of load current. IC2 is specified as an OP77GP which has the required low input offset voltage (typically 50µV) and a very low input bias current (typically Despite the relative circuit complexity, the power supply is easy to build. This view shows the prototype PC board for the supply, with all parts in place. The full assembly details will be published in next month’s issue. 1.2nA – that’s nanoamps!) This is necessary to ensure that IC2’s output is at 0V when no current is flowing through R1. Because its inputs operate at close to ground potential (ie, 0V), IC2 must be powered from balanced positive and negative supply rails. The +5.1V rail for IC2 (and for the remaining ICs) is derived from the output of the bridge rectifier via a 1kΩ resistor and 5.1V zener diode ZD1. For the negative rail we use IC6, an ICL7660 switched capacitor voltage converter which operates at 10kHz to provide a -5.1V supply. Comparator stage IC3a monitors the output voltage from IC2 and compares this with the voltage on its inverting input, as set by the current limit control VR2. This 1kΩ potentiometer and its associated 1kΩ resistor form a voltage divider network which is connected across the 2.5V reference, REF1. In operation, VR2 sets the voltage on pin 6 of IC2 at between 0V and 1.25V, corresponding to current limit settings of 0-1.25A. Because IC3a is an open collector device, its output at pin 7 is connected to the +5.1V rail via a 4.7kΩ pull-up resistor. If the voltage at the output of IC2 is greater than that set by VR2, pin 2 of IC3a is pulled high by this resistor. This also pulls pin 5 of IC1 high and switches off the regulator to provide current limiting. At the same time, pin 2 of IC3b is pulled high via diode D6 and so pin 1 switches low and LED1 lights to indicate current limiting or an overload condition. When the current subsequently falls below the preset limit, pin 7 of IC3a switches low again and the regulator turns back on. Thus, IC3a switches the regulator on and off at a rapid rate to provide current limiting. The 1MΩ resistor and 330pF capacitor at pin 2 of IC3b provide a small time delay so that LED1 is powered continuously during current limiting. Digital panel meter The LCD panel meter we’re using for this circuit has simpler interfacing requirements than those we have used in the past. It requires a +5V supply which comes from ZD1 and the resistors across its pins 5,6,7 & 8 configure it to read 2V full scale (or 1.999V to be precise). Op amp IC4 is connected as a unity gain amplifier with level shifting to provide for an offset at the input of the LCD panel meter. The non-inverting input (pin 3) of IC4 takes its DC input from switch S3 and S4 (current limit set) to monitor the current or voltage output. The current monitoring is simple because the output of op amp IC2 is 1V per amp, as already discussed. For the voltage output, we use a voltage divider consisting of a 27kΩ and 300Ω resistors in series with 5kΩ trimpot VR4 which is used for calibration. The second pole of switch S3 selects the decimal points on the LCD panel meter so that it can read up to 1.999A in current mode and 199.9V in voltage mode. In practice, the maximum reading will be around 1.2A in current mode and 40.0V in voltage mode. This means that we have more meter resolution in current mode than in voltage mode. More resolution could be obtained by range switching for the panel meter but we wanted to keep the circuit as simple as possible. Next month we will present the full constructional details of the power SC supply. JUNE 2000 61 Squash dem highs, boost dem lows Do you have problems listening to CDs in your car? Are the soft parts too soft and the loud parts too loud? This CD Compressor will solve that problem. It reduces the dynamic range of the signal while still maintaining the very clean sound of CDs. You can also use it when dubbing CDs onto cassettes or feeding them through a PA system. By JOHN CLARKE 62 Silicon Chip C OMPACT DISCS give great sound quality but they can be a problem in a car. The loud bits can be too loud and the soft bits can be lost in the general cabin noise from the engine, the road and wind roar. To solve the problem you need to “compress” the dynamic range of the signal so that the loud parts are not quite so loud and the soft parts are not nearly so quiet. In operation, the CD Compressor continuously adjusts the signal level by amplifying the quiet passages and attenuating the louder passages, so that the overall volume is much more constant. The degree to which the signals are amplified and attenuated can be adjusted to suit the ambient noise. One problem with many CD compressors is that they can give increased noise at the lower signal levels because of the increased gain. This problem is largely avoided in this design because it features a “downward expander” which reduces the gain below a certain adjustable threshold point. As a result, noise is considerably reduced compared to compression without the downward expansion. Tape recording A CD compressor is also a boon when you want to dub your CDs onto cassettes. Although it’s possible to copy them direct without using a compressor, the results are often quite poor – most cassette decks can only really handle a dynamic range of about 40dB and that is far less than many CDs; low level signals will be lost in the background noise, while loud passages will be distorted as the signal is clipped by the saturation Main Features • • • • • • • • • Compact size Stereo operation Adjustable compression ratio Downward expander to reduce noise at low levels Fast attack rate to prevent overload Slow decay rate for low distortion Low noise operation Mute facility & bypass switch 12V automotive (DC) or AC plugpack supply limit of the tape. Generally, only a mild amount of compression is required to give a huge improvement in the recording quality. In effect, the compressor reduces both the noise and the distortion. The noise is reduced because low-level signals are amplified to a level above the noise floor produced by the tape. At the same time, the distortion is reduced because high-level signals are attenuated to prevent tape saturation. PA systems and mood music An audio compressor is also a “must-have” item when you want to provide low-level “mood” or background music at a dinner party. Or maybe you want to pipe music into a restaurant via the PA system. Again, the problem is the same – all those people eating and talking provide a high noise level and the soft passages of the CD get completely drowned out. With a CD compressor, the music can heard all the time without being too obtrusive in the louder passages. The SILICON CHIP CD Compressor is housed in a small slimline plastic case which can be easily fitted into a car or attached to a lounge-room hifi system. In has two rotary controls to adjust the amount of compression (or compression ratio) and the volume. The compression adjustment range is from 1:1 (no compression) all the way up to 3:1. At high compression ratios, the volume is relatively constant and the dynamic range is very narrow, so that the compressor behaves like an automatic level control (ALC). The volume control adjusts the output level by about 15dB. Also on the front panel are three toggle switches, labelled “In/Out”, “Mute” and “Power”. As implied, the In/Out switch switches the compression in or out, while the Mute switch is used to “kill” the signal at the outputs if required. Block diagram Fig.1 shows the block diagram for the CD compressor. It uses two voltage controlled amplifiers (VCAs) – one for each channel – plus several amplifier and control blocks. IC1 is the VCA for the left channel while IC2 is the VCA for the right channel. These stages are basically variable gain amplifiers, their gain at any one instant depending on the voltage applied to their control inputs. As a result, an audio signal applied to their inputs can be amplified or attenuated, depending on the control voltage. Note that both the left and right channel VCAs use the same control Fig.1: block diagram of the CD Compressor. The left and right channel signals are fed to separate voltage controlled amplifiers (VCAs) which continuously vary their gain to compress the output signals. The control voltage for the VCAs is derived by mixing the inputs and then feeding them to precision rectifier and logarithmic amplifier stages. JUNE 2000 63 Fig.2: the top waveform in this scope shot shows a 1kHz input signal. It begins as a 250mV signal and then “bursts” to 1V RMS, representing a 12dB range. The lower trace shows the compressor’s output at 2:1 compression ratio. The attack time is about 5ms and is the time taken for the burst signal to settle to its compressed level. voltage, so that their gains track each other. Following each VCA is an amplifier stage (IC3b & IC3c) and a volume control (VR1a & VR1b) to set the output level. Let’s now briefly describe how the control voltage is derived. As well as passing to the VCA inputs, the signals at the left and right channel inputs are also fed to mixer amplifier IC3a to produce a composite mono signal. This signal is then fullwave rectified and the resultant waveform fed to a logarithmic amplifier stage based on op amps IC4c & IC4d and transistors Q1 and Q2. The signal output from this stage is the logarithm of the rectified signal at its input. From here, the signal is buffered (IC5a) and filtered, with a capacitor used to store the average value and produce a smooth DC voltage. The attack rate for the filter is set by resistor R1, while the decay rate is set by R2. The logarithmic (log) amplifier stage is included for two reasons. First, the gain of the VCAs changes in logarithmic fashion if they are controlled using a linear control voltage. However, that’s not what we want here. Instead, we want the VCAs to provide a linear gain response and this is achieved by controlling them with a logarithm of the composite input signal level. 64 Silicon Chip Fig.3: the top trace of this scope shot shows the falling edge of the tone burst signal depicted in Fig.2. The lower trace shows the output from the compressor and also indicates the decay time; ie, the time taken for the level to settle after the sudden drop in input signal level. This decay time is about 30ms. The second reason is so that the filter following the log amplifier can provide a linear dB response over time. Without the log amplifier, the filter would take a long time to settle after a large drop in signal level at the input but would be much faster for small reductions in signal level. The log amplifier helps to ensure a linear filter response for both large and small signal level changes. Following the filter stage, the signal is again buffered (this time using IC5b) and then fed to a “threshold and ratio control” block (IC5c, IC5d, Q5, VR6 & VR7). This stage sets the compression ratio (ie, the amount of compression) and passes the control voltage on to the VCAs. Circuit details Refer now to Fig.4 for the circuit details. It uses two Analog Devices SSM2018 VCAs (IC1 & IC2) which have excellent noise and distortion figures. There are also 12 op amps but these are contained in just three TL074 quad op amp packages so it’s not as complicated as it looks. Before we go further, some readers might wonder why we did not use another Analog Devices chip, the SSM2120 or SSM2122, to do virtually the whole circuit instead of using quite a few separate op amps. The answer is that we would have liked to have taken that approach but the SSM2120/2122 chip has been discontinued. Note also that there are two versions of our new CD Compressor circuit, one for use with an AC plugpack and the other for use with a 12V DC supply; ie, suitable for cars. Fig.4 shows the AC version, with the values shown in brackets for the DC version. The left and right channel VCA circuits are identical, so we’ll consider only the left channel. As shown, the left audio input signal is applied to pins 6 & 4 of IC1 via a 10µF bipolar capacitor and an 18kΩ series resistor. This resistor and the 15kΩ resistor between pins 3 & 14 set the gain of the VCA to 0.83 when the control input at pin 11 is at 0V. However, for the 12V DC version, the gain is reduced to 0.31 to prevent clipping with the maximum 2V input signal from a CD player. The 47pF capacitor between pins 5 & 8 is included to compensate the amplifier and prevent instability. Similarly, the capacitor between pins 3 & 14 provides high frequency rolloff. Trimpot VR2 provides adjustment for “control feedthrough”. This is set to minimise any control signal feedthrough from pin 11 to the pin 14 output of the VCA. As an aside, the feedthrough has already been laser-trimmed on the chip by the manufacturer but some further improvement can usually be achieved using the trimpot. The 120kΩ (68kΩ) resistor at pin 12 sets the quiescent current for the class-B output stage at pin 14. Again, the IC is laser-trimmed at the factory, in this case to obtain the best distortion characteristics when the current into pin 12 is 95µA. This means using a 120kΩ resistor when the supply is ±12V (as for the 12V AC-powered version) or a 68kΩ resistor when the circuit is powered from a 12V DC supply (±6V). The compressed audio output signal appears at pin 14 of IC1 and is fed to op amp IC3b. This stage is wired as an inverting amplifier with potentiometer VR1a in the negative feedback loop between pins 8 & 9. This pot allows the gain to be adjusted between -1 and -5.55 and basically functions as a volume control by setting the output level. Following IC3b, the signal is coupled to the output via a 100Ω resistor, a 10µF capacitor and a set of relay contacts. The relay is included to provide muting at switch-on and also to allow the user to mute the output at any time. The associated 10kΩ resistor to ground provides a charging path for the 10µF capacitor. VCA control OK, so much for the VCAs and the audio output stages. Let’s now take a look at how the control voltage is derived for the VCAs. Actually, there’s quite a lot of circuitry involved here, involving no less than nine op amp stages: IC3a, IC4a-IC4d and IC5a-IC5d. IC3a is the mixer which combines the left and right channel audio signals. As shown on Fig.4, these signals are both fed to the pin 2 inverting input via a 10µF capacitor and series 10kΩ resistor. IC3a operates with a gain of -1.5 for the AC-powered version and -0.33 for the 12VDC version. The higher gain of the AC-powered version means more signal for the following stages and this gives better compression control. The feedback capacitor between pins 1 & 2 of IC3a rolls off its response above about 19kHz. The output appears at pin 1 and is AC-coupled to the precision rectifier which comprises IC4a, IC4b and diodes D1 & D2. This stage operates as follows. When the input signal goes positive, pin 1 of IC4a goes low and forward biases D2. As a result, the gain is set Parts List 1 PC board, code 01106001, 133 x 103mm 1 ABS instrument case, 140 x 110 x 35mm 1 front panel label, 131 x 31mm 1 DPDT toggle switch (S1) 2 SPDT toggle switches (S2,S3) 2 12V reed relays (relays 1 & 2) 2 16mm black knobs 1 4-way RCA socket strip 1 2.5mm DC socket 1 10kΩ 16mm dual-gang log pot (VR1) 5 20kΩ horizontal mount trimpots (VR2-VR6) 1 10kΩ 16mm linear pot (VR7) 1 500mm length of 0.8mm tinned copper wire 1 300mm length of red mediumduty hookup wire 1 300mm length of black mediumduty hookup wire 12 PC stakes Semiconductors 2 SSM2018P VCAs (IC1,IC2) 3 TL074, LF354 quad op amps (IC3-IC5) 1 7555 CMOS timer (IC6) 2 BC549 NPN transistors (Q1,Q2) 1 BC547 NPN transistor (Q3) 1 BC557 PNP transistor (Q4) 6 1N914, 1N4148 diodes (D1-D6) Capacitors 1 470µF 25VW electrolytic 1 220µF 50VW electrolytic 8 10µF 63VW electrolytics 9 10µF bipolar electrolytics 1 1µF 16VW PC electrolytic 2 0.1µF MKT polyester 1 680pF ceramic 3 560pF ceramic 1 390pF ceramic to -1 by the 20kΩ input and 20kΩ feedback resistors. The output signal appears at the anode of D2 and is fed to the inverting input (pin 13) of IC4b via a 10kΩ resistor. IC4b operates with a gain of -2 for this signal path, as set by the 20kΩ feedback resistor and the 10kΩ input resistor. This means that the overall gain of the signal through IC4a & IC4b is -1 x -2 = +2. However, there’s a complicating factor here. Pin 13 of IC4b is also fed 1 330pF ceramic 2 47pF ceramic 1 10pF ceramic Resistors (0.25W, 1%) 4 10MΩ 2 18kΩ 1 1MΩ 15 10kΩ 1 470kΩ 2 4.7kΩ 1 100kΩ 2 3.9kΩ 1 47kΩ 6 2.2kΩ 1 33kΩ 3 1kΩ 1 22kΩ 6 100Ω 4 20kΩ Extra parts for AC plugpack version 1 12V AC or DC 300mA plugpack 1 7812 +12V regulator (REG1) 1 7912 -12V regulator (REG2) 2 1N4004 1A diodes (D7,D8) 1 470µF 25VW electrolytic capacitor 1 10µF 16VW PC electrolytic capacitor 1 560pF ceramic capacitor 2 330pF ceramic capacitor 2 1MΩ 0.25W 1% resistors 2 120kΩ 0.25W 1% resistor 3 15kΩ 0.25W 1% resistor Extra parts for 12V DC version 1 16V 1W zener diode (ZD1) 1 .0022µF MKT polyester capacitor 2 .001µF MKT polyester capacitor 2 470kΩ 0.25W 1% resistors 2 5.6kΩ 0.25W 1% resistors 1 4.7kΩ 0.25W 1% resistor 1 3.3kΩ 0.25W 1% resistor 2 2.2kΩ 0.25W 1% resistors 1 100Ω 0.25W 1% resistor 1 10Ω 0.25W 1% resistor directly with the mixer signal via a second 20kΩ resistor and so operates with a gain of -1 for this signal path. Adding the two gains therefore gives us a total gain of +1 for positive-going signals. When the input to the precision rectifier swings negative, D1 is forward biased and clamps pin 1 of IC4a to 0.6V (ie, one diode drop) above ground. This effectively disables IC4a and so IC4b simply amplifies the output of IC3a with a gain of -1. Because JUNE 2000 65 66 Silicon Chip Fig.4: the circuit diagram for the CD Compressor. IC1 & IC2 are the VCAs and these drives op amps IC3b & IC3c. Most of the rest of the circuit is used to produce the control voltage for the VCAs. JUNE 2000 67 Fig.5: follow this wiring diagram to build the 12V AC-powered version. This is the version to build if you don’t intend using the unit in a car. the input signal is negative, the signal at pin 14 is positive. As a result, pin 14 of IC4b always swings positive and op amps IC4a & IC4b together operate with an absolute gain of 1. This means that the stage operates as a precision full-wave rectifier. Trimpot VR4 adjusts the offset voltage at pin 12 of IC4b. It is set so that the full-wave rectified output is symmetrical for both positive and 68 Silicon Chip negative input swings, at low signal levels. Op amps IC4c and IC4d comprise the logarithmic amplifier referred to earlier in the block diagram description. This cir cuit is based on the inherent logarithmic relationship between the collector current and the base-emitter voltage of a bipolar transistor. As can be seen, transistor Q2 is connected as a grounded base amplifier. It forms part of the negative feedback loop for op amp IC4d, along with the 10kΩ and 1kΩ feedback resistors and the base-emitter junction of transistor Q1. Q2’s collector operates with a constant current of 12µA via the 1MΩ (470kΩ) resistor connected to the positive supply rail. This sets Q2’s base-emitter voltage to a fixed value. By contrast, Q1’s base-emitter voltage depends on the collector current Table 1: Capacitor Codes           Value IEC Code EIA Code 0.1µF 100n 104 .0022µF 2n2 222 .001µF 1n0 102 680pF 680p 681 560pF 560p 561 390pF 390p 391 330pF 330p 331 47pF 47p 47 10pF 10p 10 which flows via the 3.9kΩ resistor at pin 9 of IC4c. And that, in turn, depends on the output level from IC4b in the precision rectifier. IC4d’s output depends on the difference between the base-emitter voltage of Q2 and the base-emitter voltage of Q1. It also depends on the gain of this stage which is set by the 10kΩ and 1kΩ feedback resistors connected to Q1’s base. Q1’s collector current varies with the input voltage and this affects its base-emitter voltage in a logarithmic fashion. This means that IC4d’s pin 7 output will be the log of the input. It will be at 0V when the currents through the collectors of Q1 and Q2 are equal at 12µA. Trimpot VR5, along with op amp IC4c, allows the offset voltages to be A compact, low-profile instrument case houses the PC board (AC-powered version shown). Note the use of shielded cable to wire the input sockets. removed and ensures that the log amplifier operates correctly over several decades of signal level. Note that this type of log amplifier will have a temperature dependent output since the base-emitter voltage of a transistor varies by about 2mV/°C. This variation is compensated for by the reverse temperature characteristics of the two VCAs (IC1 & IC2). Attack and decay Following the log amplifier, the control signal is filtered using IC5a, Table 2: Resistor Colour Codes  No.  4  3  3  2  1  1  1  1  4  2  3  15  2  3  2  1  8  3  7  1 Value 10MΩ 1MΩ 470kΩ 120kΩ 100kΩ 47kΩ 33kΩ 22kΩ 20kΩ 18kΩ 15kΩ 10kΩ 5.6kΩ 4.7kΩ 3.9kΩ 3.3kΩ 2.2kΩ 1kΩ 100Ω 10Ω 4-Band Code (1%) brown black blue brown brown black green brown yellow violet yellow brown brown red yellow brown brown black yellow brown yellow violet orange brown orange orange orange brown red red orange brown red black orange brown brown grey orange brown brown green orange brown brown black orange brown green blue red brown yellow violet red brown orange white red brown orange orange red brown red red red brown brown black red brown brown black brown brown brown black black brown 5-Band Code (1%) brown black black green brown brown black black yellow brown yellow violet black orange brown brown red black orange brown brown black black orange brown yellow violet black red brown orange orange black red brown red red black red brown red black black red brown brown grey black red brown brown green black red brown brown black black red brown green blue black brown brown yellow violet black brown brown orange white black brown brown orange orange black brown brown red red black brown brown brown black black brown brown brown black black black brown brown black black gold brown JUNE 2000 69 Fig.6: this is the wiring diagram for the 12V DC-powered version. Take care to ensure that all parts are correctly placed and that the polarised parts go in the right way around. transistors Q3 & Q4, resistors R1 & R2 and capacitor C1. At first glance, this may appear to be an op amp driving a complementary emitter follower but in fact it is more like an active filter which controls the attack and decay times for the compressor. In practice, R1 and C1 provide the attack time while R2 and C1 set the decay time. When the voltage on pin 12 of IC5a is greater than the voltage across C1, pin 14 goes high and turns on tran70 Silicon Chip sistor Q3. This rapidly charges C1 via Q3’s 1kΩ emitter resistor (ie, via R1). The rate of charge depends on the difference between the voltage at pin 12 and the voltage across C1. If the difference is small, then the current through R1 will also be small and C1 will charge relatively slowly. Conversely, if the difference is large, there will be more voltage across R1 and C1 will charge at a faster rate. The idea behind this is to prevent overload when rapid, large signal changes occur. At the same time, it prevents sudden gain changes in the VCA for small changes in signal level. The discharge cycle for C1 is quite different to the charging cycle. When the signal at pin 12 of IC5a goes lower than the voltage across C1, pin 14 goes low. Q3 now turns off and Q4 turns on and discharges C1 via the 1MΩ resistor connected to the nega tive supply rail. Because C1 is only one or two volts above or below ground at most, the discharge occurs in a relatively linear region of the exponential charge/ discharge curve. As a result, we get an equivalent linear rate of change in gain (in dB) for the two VCA’s. IC5b amplifies the voltage on C1 by a factor of two and applies the resultant signal to trimpot VR7 – the ratio control potentiometer – via a 22kΩ resistor. The signal on the wiper of this pot is the control signal and this is applied to the pin 11 control inputs of the two VCAs (IC1 & IC2). In operation, VR7 allows the control voltage to be adjusted from 0V where there is no compression through to the maximum control voltage where the compression is about 3:1. Downward expander IC5c and IC5d make up the “downward expander” circuit. IC5c monitors the control voltage from IC5b at its inverting (pin 6) input and a threshold voltage set by VR6 is fed to its non-inverting (pin 5) input. Its output appears at pin 7 and drives unity gain buffer stage IC5d which has diode D5 in the negative feedback loop. When the control voltage from IC5b is above the threshold voltage on pin 5, pin 7 of IC5c is low and so is pin 8 of IC5d. Diode D5 will therefore be reverse-biased and so IC5d’s output has no effect on the control voltage applied to the VCAs. However, if IC5b’s output voltage dips down to the threshold voltage, pin 7 of IC5c begins to go high. IC5d’s output also starts going high and this forward biases D5 which pulls the control voltage applied to VR7 high via a 2.2kΩ resistor. In practice, this means that the control voltage applied to VR7 can not drop below the set threshold. What happens is that if pin 6 of IC5c continues to go low, IC5d pulls the control voltage on VR7 even higher. As a result, the gain at very low signal levels is further reduced with a consequent reduction in noise. Muting IC6, switch S2 and relays 1 & 2 form the muting circuit. This circuit automatically mutes the signal at switch-on and switch-off to prevent unwanted noise and also allows the user to manually switch the muting in. Let’s see how this all works. Performance Of Prototype Compression Ratio: adjustable from 1:1 to 3:1 Distortion: .04% THD at 100Hz to 10kHz with 1V input and 1:1 compression; .08% THD at 1kHz; .06% at 10kHz; 1.6% at 100Hz with 1V input and 2:1 compression Temperature Drift: 1dB change over a 40°C temperature variation (worst case maximum compression) Frequency Response: -3dB at 10Hz and 22kHz into 4.7kΩ load (worst case maximum volume setting) Attack & Decay Times: 5ms & 30ms – see oscilloscope traces (Figs.2 & 3) Frequency Response: -3dB <at> 10Hz and 22kHz Separation Between Channels: 88dB <at> 100Hz; 67dB <at> 1kHz; 50dB <at> 10kHz 12VDC version Signal-To-Noise Ratio: 92dB wrt 2V 20Hz to 20kHz bandwidth (96dB A-weighted) at 1:1 compression; 82dB wrt 2V 20Hz to 20kHz bandwidth (87dB A-weighted) at 2:1 compression and 1mV (-66dB) downward expansion threshold; 71dB and 82dB A-weighted at 100µV (-86dB) downward expansion threshold Compression Linearity: within 1dB over an 80dB range at 2:1 compression Signal Handling: 2.16VAC RMS before clipping with 13.8V supply and minimum volume setting (worst case at 1:1 compression) 12VAC version Signal-To-Noise Ratio: 100dB with respect to 2V 20Hz to 20kHz bandwidth (103dB A-weighted) at 1:1 compression; 85dB wrt 2V 20Hz to 20kHz bandwidth (90dB A-weighted) at 2:1 compression and 1mV (-66dB) downward expansion threshold; 80dB and 85dB A weighted at 100µV (-86dB) downward expansion threshold Compression Linearity: within 1dB over an 85dB range at 2:1 compression Signal Handling: 2.2VAC RMS before clipping and minimum volume setting (worst case at 1:1 compression) When power is applied, the pin 2 trigger input of IC6 is initially pulled low via a 1µF capacitor. As a result, pin 3 is high, the relays are off and no audio signals appear at the outputs (ie, the signal is muted). The 1µF timing capacitor now charges via a 470kΩ resistor. When the voltage across it reaches 2/3Vcc (ie, 2/3rd of the supply voltage), pin 3 goes low and turns on the relays. This closes the relay contacts and allows the audio signals to pass through to the output sockets. The circuit can be manually muted at any time by closing switch S2. This quickly discharges the 1µF capacitor to below 1/3Vcc via a 100Ω resistor and so pin 3 switches high and turns off the relays. Similarly, the contacts of S1b close when the power switch is turned off to perform the same job. Diode D5 quenches any high voltage spikes that would otherwise be generated when the relays turn off, to prevent damage to IC6. Power supply As mentioned earlier, power for the CD Compressor can come from either a 12VAC plugpack or a 12V DC supply as in a car. We’ll look at the AC-powered version first, which is shown at bottom lefthand corner of Fig.4. Power from the 12VAC plugpack is switched via S1 to half-wave rectifiers D8 and D7. D8 provides a nominal +17V supply rail, while D7 provides a -17V rail. These rails are then filtered using 470µF capacitors and regulated to +12V and -12V using 3-terminal regulators REG1 and REG2. JUNE 2000 71 AUDIO PRECISION GAIN AMPL(dBV) vs AMPL(Vrms) 10.000 12 FEB 100 00:40:22 0.0 -10.00 -20.00 -30.00 -40.00 -50.00 -60.00 -70.00 -80.00 300u 1m 10m The 12V DC supply circuitry is shown at the bottom righthand corner of Fig.4. 12V is applied via power switch S1 and a 10Ω decoupling resistor. Zener diode ZD1 clamps any spike voltages above 16V, a necessary precaution when using an automotive power supply rail. A half-supply ground is derived using IC3d. The 2.2kΩ resistors at pin 5 split the 12V supply in half, with decoupling provided by a 10µF capacitor. This gives us nominal +6V, 0V (at the midpoint) and -6V rails. The 0V rail is buffered using op amp IC3d and its output connects to the earth rail. The 100Ω resistor at the output isolates the op amp from capacitive loads. Construction Construction is straightforward, with most of the parts assembled onto a PC board coded 01106001. This is fitted into a compact plastic case measuring just 140 x 110 x 35mm high. Start by checking the PC board for any etching defects by comparing it with the published pattern (Fig.8). This done, check that the four corner mounting holes are drilled to 3mm and that the two half-moon cutouts have been made on either side of the board to clear the mounting bosses in the case. It may also be necessary to enlarge the holes for the two potentiometers and for the PC stakes at the external wiring points. Fig.5 shows the parts layout diagram for the AC-powered version 72 Silicon Chip 0.1 1 2 Fig.7: this graph shows the input versus output characteristics of the compressor at three different compression ratios. The horizontal axis represents the input signal level, ranging from 300µV to 2V (a level change by a factor of 10 represents 20dB). The vertical axis is the corresponding compressor output with the volume set at maximum. The steepest sloping line is for 1:1 compression. This is simply a straight line and shows a 10dB increase in signal output level for every 10dB increase at the input (ie, the signal is not compressed). The central line shows the 2:1 compression slope and this provides a 5dB change in signal for a 10dB input change. Note that the downward expansion point is set at about 1.5mV (62dB below 2V) and the signal is reduced at a rapid rate for input levels below this. The remaining curve shows the 3:1 compression slope, where the signal is reduced to a 20dB range for a 60dB input. only, while the DC version is shown in Fig.6. We recommend that you build the AC version if you don’t intend using the CD Compressor in a car. Start the assembly by installing all the wire links and the ICs. Make sure that the ICs are all correctly oriented and that the correct device is used in each location. The resistors can be installed next. Most of these are mounted end-on to save space, which means that you will have to bend one of their leads through 180° so that they go through the holes in the board. Table 2 shows the resistor colour codes but it’s also a good idea to check them on a multimeter, just to make sure. Now install the transistors and diodes, followed by the capacitors and trimpots. Note that the electrolytic capacitors marked BP or NP are not polarised and can be installed either way around. Finally, complete the board assembly by installing the two PC-mount pots, the relays and PC stakes at the external wiring points. Take care with the two pots; VR1 (Level) is a 10kΩ log type, while VR7 (Ratio) is a 10kΩ linear type. Case preparation Work can begin on the front panel, using the label as a template for drilling out the holes. You will need to make five holes, three for the toggle switches and two for the pot shafts. The rear panel requires holes for the 4-way RCA socket panel and the power socket. Note that the centre-line for the RCA sockets is located 8mm down from the top edge of the rear panel, to allow room for the wiring. This means that the top edge of the RCA socket panel requires trimming, so that it doesn’t interfere with the lid. Once all the drilling has been completed, attach the front panel label, then mount the rear-panel hardware. This done, cut the pot shafts to match the knobs, then fit the front panel over them and slide the entire assembly into the case. The PC board can then be secured using self-tapping screws into the matching pillars in the base. Finally, mount the toggle switches on the front panel and complete the wiring, as shown in Fig.5 or Fig.6. Note that shielded cable is used for the signal inputs between the RCA sockets and the PC board but the signal outputs and all other wiring can be run using light-duty hookup wire. Do not forget to solder a length of tinned copper wire along the RCA socket earth tabs, as shown. It’s also necessary to earth the body of the volume control pot using a short length of tinned copper wire back to an adjacent PC stake. Scrape away the plating on the pot body using a sharp utility knife before soldering to it. Testing Now for the smoke test. First, check your work carefully, then apply power, connect the negative lead of your multimeter to the COM stake on the PC board and check the supply voltages. If you built the AC-powered version, there should be +12V on pin 2 of IC1 & IC2, pin 4 of IC3-IC5 and on pins 4 Fig.8: these are the full-size artworks for the front panel and the PC board. Check your board carefully for etching defects before installing any of the parts. & 8 of IC6. Alternatively, there should be +6V present on all these pins for the 12V DC version. The negative supply can be checked now. There should be -12V (-6V for the DC version) on pins 10 & 16 of IC1 & IC2 and on pin 11 of IC2-IC5. IC6 should have 0V on pin 1 for the 12VAC version and -6V for the 12VDC version. If everything checks out so far, set VR6 fully clockwise and set all the remaining trimpots to their midpoint positions. This done, switch your multimeter to read in millivolts DC and attach the probes between pin 1 of IC4a and pin 14 of IC4b. Adjust VR4 so that the reading is as close to 0mV as possible under no-signal conditions (ie, do not apply any audio signals to the inputs). This sets the precision rectifier so that it gives a symmetrical output for both positive and negative signal swings at low levels. Now connect your multimeter be- tween pin 7 of IC4d and ground and adjust VR5 anticlockwise until the voltage suddenly jumps negative to about -10V (-5V for the 12VDC supply version), then back off slightly until the meter shows a voltage of about -1V to -2V – ie, rotate the pot anticlockwise to find the point where it exactly jumps fully negative and then rotate the pot back very slightly from this point. The dynamic range for the log amplifier is now at maximum. VR6, VR2 and VR3 are set by testing the unit with a CD player and audio amplifier. To do this, connect the leads from the CD player to the left and right inputs and connect the outputs from the compressor to the amplifier. Now set the ratio control fully clockwise, apply power and adjust VR6 anticlockwise so that any background noise is reduced to an acceptable level. Next, toggle the In/Out switch between its two settings and check for noise clicks in the loudspeakers when this is done (you may need to turn the volume up on the amplifier to hear any clicks). Adjust VR2 (left channel) and VR3 (right channel) to minimise any clicking noises that you do hear when the In/Out switch is toggled (this adjustment minimises the control feedthrough into the audio signal). Using it In use, the compression ratio should generally be set to the minimum possible before low-level signals are lost in the background noise. Some readers may also wish to alter the attack and decay times for the compressor. As mentioned earlier, resistor R1 (1kΩ) sets the attack time, while R2 (1MΩ) sets the decay rate. Generally, a fast attack time is recommended to prevent transient overload of the signal. At the same time, a slower decay rate is recommended to minimise distortion. If the decay rate is too slow, you may find that the sound has a characteristic “pumping” effect due to the gain increasing too slowly after shutting down on a transient signal. This pumping action is more prevalent with high compression ratios. To increase the decay time, increase R2’s value and to decrease the decay time, reduce R2. Similarly, the attack time can be increased by increasing R1. Note that increasing the compression ratio will also reduce the volume because the louder passages are attenuated. The overall level can be restored SC using the volume control. JUNE 2000 73 SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au Speaking from experience, I know that troubleshooting electrical/electronic equipment in the field can be a real pain in the proverbial. Lugging large, supposedly “portable” and usually expensive pieces of test equipment around the country can really test the nerves – as well as the muscles. Could this be the answer? TiePie HANDYPROBE HP2 Review by PETER SMITH T HE HIGH COST of portable test equipment also means that many companies cannot afford to outfit each engineer with his or her own gear. If you have a problem in Sydney but the gear’s in Perth, too bad – the problem has to wait and the customer might not be understanding... TiePie Engineering, a Dutch company which specialises in computer controlled measuring equipment, has come up with a unique solution to this field service dilemma in the Handyprobe 2. The Handyprobe 2 incorporates a storage oscilloscope, spectrum analyser, voltmeter and transient recorder all in a package that fits in the palm of your hand! The probe plugs into the parallel port of any PC and in conjunction with DOS or Windows software provides a comprehensive range of data acquisition functions. It is powered directly from the parallel port connection (no external supply or batteries are required) so is ideally suited for use with laptop computers. In fact, the probe together with its integral cable could easily TiePie engineering slide into a spare spot in most laptop bags. With an input range of 0.5V to 400V full scale and a maximum sampling speed of 20MHz (TiePie also produce 1,2,5 and 10MHz versions), the Handyprobe can handle just about anything you can throw at it. Here are just a few “typical” applications suggested by TiePie: serial data communications, TV signals, power inverters, industrial production machines, office equipment, sensor readings (eg, temperature, pressure and humidity), line measurements, inrush currents, line distortion, sound and vibration analysis, trend measurements, and once-only disturbance detection measurements. Instrument settings can be saved and restored from disk at will, saving time on-site and perhaps reducing the required level of operator training. To keep the cost down, TiePie have provided only single-channel acquisition in the Handyprobe 2. As with most storage ‘scopes, the Handyprobe includes a reference channel that can be used to compare a stored measurement with a second (live) measurement, so a second channel is usually not required. As mentioned above, the Handyprobe 2 software runs under both DOS and Windows. PC hardware requirements are minimal - the basic DOS version will run on an 80286 or even 8088-based (IBM-XT) PC. The Windows version requires a 486DX2-66 or faster processor with at least 8MB of RAM. TiePie recently released 32-bit versions of their software for Windows 95/98 and Windows NT and this is what we used for our review. Walking the dog The newer 32-bit software wasn’t supplied with our review package, so we downloaded it from TiePie’s web site at www.tiepie.nl Installation was a piece of cake and took about five minutes. An additional driver is required if you’re running Windows NT 4 (or JUNE 2000 77 It’s not quite plug’n’play – it’s plug’n’work! The TiePie Handyprobe HP2 is definitely all business . . . but it’s a pleasure to use. Shown here are the instrument itself, software and instruction manuals. Windows 2000) and this can also be downloaded from the same site. Launching the Handyprobe 2 software displays a floating toolbar on the Windows desktop (see Fig.1). The toolbar provides access to all four of the available instruments, as well as to basic program settings (see Fig.2). The ’scope, voltmeter and spectrum analyser instruments can all be active simultaneously, whereas the transient recorder must run independently. Let’s take a look at each of the instruments and their capabilities in a little detail. Note that we’ve provided more detail on the oscilloscope and voltmeter instruments, as these will likely be of most interest to our readers. Storage oscilloscope TiePie boast that their instruments are “plug and measure”. This is, of course, one of the benefits of a totally software-controlled instrument, and we were keen to try it out. We connected the probe to our trusty Silicon Chip Sine/Square Wave Generator, activated the oscilloscope and hit the Auto SET button. In less than a second the input was scaled nicely (both horizontally and vertically) and correctly triggered (see Fig.3). Auto SET places the instrument in auto-ranging mode, so for many simple measurements you may not need to do any setup at all. All instrument settings are available from the main toolbar via pulldown menus, with many often-used settings also controllable with single-keystroke shortcuts. Vertical axis The CH1 pull-down menu provides access to all vertical axis settings. Input sensitivity ranges from 0.5V to 400V full scale, configurable from the Sensitivity selection (see Fig.4). A l t e r n a t i v e l y, hitting the F5/F6 keys clicks over Fig.1: the instrument toolbar provides a convenient way of activating the instruments. All except the transient recorder can be active simultaneously. 78 Silicon Chip to the next lowest/highest setting - a bit like using that rotary switch on CRT-based oscilloscopes. Measured values can be enlarged or reduced using the “Software Gain” function – TiePie calls this vertical axis magnification. A closely related function called “Software Offset” applies a positive or negative bias to the vertical axis. Once again I was reminded of the conventional ‘scope and the equivalent “position” knob (got to kick that habit). Both the Software Gain and Offset can also be changed directly on the display by clicking and dragging points on the vertical axis – great Fig.2: settings common to all instruments are accessible from the toolbar. Although not mentioned in the text, instrument calibration data can be defined on the Hardware tab. Fig.3: the “oscilloscope”. Comment balloons provide an easy way of annotating waveforms before printing. feature! The Units of measure, Units of gain and Units of offset functions provide for custom vertical axis marking and scaling, making tailoring for specific measuring tasks quite simple. For example, suppose you have a temperature probe whose output changes by 1V for every 10 degrees of temperature change. By setting the Units of measure to “Degrees C” and Units of gain to “10”, the vertical axis displays temperature change directly in degrees. Other options on this menu allow choices of true or inverted signal, and either AC or DC signal coupling. Horizontal axis Unlike its more conventional analog cousin, the digital scope’s timebase is dependant on both the rate at which the incoming signal is sampled and how many samples are stored and subsequently displayed across the horizontal axis. The Handyprobe 2 has a maximum sampling rate of 20 million samples/ second and a memory depth (also called record length) of 32,760. Both the sample rate and record length are configurable from the Timebase pulldown menu (see Fig.5). Naturally, the Handyprobe software automatically adjusts the time/ div values along the horizontal axis when the sample rate and record length are changed. Also accessible from the Timebase menu are two options that allow closer examination of any part of the acquired signal. Record View Gain provides horizontal axis magnification, whereas Record View Offset allows display of a particular section Fig.4: manually setting the input range. of the record. Note the scroll bar directly below the horizontal axis – this provides a much more convenient way of panning through the record than manually entering the Record View Offset. After fiddling with the software gains and offsets for a while to get my test signals to look the way I wanted, I started to wish there were an easier way – and there is! A “zoom” button on the toolbar allows you to select a region of the display that you would like to examine, and the correct gains and offsets are automatically applied to both the horizontal and vertical axes to make it all happen. A feature in digital ‘scopes that I’ve often found useful is their ability to display a number of samples prior to triggering. On the Handyprobe, the number of pre-trigger samples can be set an- Table 1: TiePie Handyprobe 2 Hardware Specifications Input channels 1 analog A/D converter: resolution conversion time effective data throughput 8 bits, 0.39% 50ns 1M, 2M, 5M, 10M or 20 Mega samples/sec (depending on model) Analog input: sensitivity maximum voltage impedance coupling accuracy bandwidth 0.5V to 400V full scale 500V 1MΩ / 30pF AC/DC 1% ± 1 LSB DC to 2MHz Trigger system: level adjustment resolution pre-trigger post-trigger 0 - 100% of full scale 0.39%, 8 bits 0 - 32768 samples (0 - 100%) 0 - 32768 samples (0 - 100%) Maximum sample rate 1, 2, 5, 10 or 20M samples/sec (depending on model) Memory 64K words Interface PC-compatible parallel port (LPT1, 2 or 3) Cable length 1.8m Power Derived from LPT port Dimensions 22 x 125 x 43mm (H x L x W) Weight 260 grams JUNE 2000 79 Fig.5: selecting the sample frequency (or rate) from the Time base menu. The faster the sample rate, the less time it takes to fill an entire record. As shown here, at 10kS/sec the record is filled in just 100ms. ywhere from zero to the maximum record size. A second scroll bar at the bottom of the display allows this value to be changed instantly. Triggering As expected, the Handyprobe includes variable level triggering on a rising or falling slope. Slope position, level and hysteresis can all be set from the Trigger pull-down menu. Easier still, these values can be changed by clicking and dragging the trigger symbol next to the vertical axis - too easy! Auto level triggering is also selectable; when active an “A” is visible next to the trigger symbol. Noisy signals and glitches Noisy signals can be “cleaned up” by using Handyprobe’s signal averaging feature. A number of user-definable samples (4 - 256) is taken and the results are averaged, removing unwanted noise. Spotting a glitch on a real-time display is often impossible - but TiePie have the bases covered here, too. Envelope mode keeps a record of the highest and lowest samples since last reset and compares these values to each successive sample. When a sample that exceeds either of these limits is detected, a vertical line is drawn on the display at that point and the value is stored as the new lowest (or highest). Envelope mode can be reset at any user-definable measurement interval – or it can run indefinitely. you want for a particular measuring task, you can save those settings to disk for later reuse. And there is no limit to the number of settings files you can create, either. Another indispensable feature allows waveforms (both live and reference channels) to be saved on disk for later examination. This would also be handy for record keeping or documentation, especially when combined with the hardcopy feature (see below). Data files can be saved either in binary or ASCII format, allowing further processing by other applications. Waveforms can also be saved to disk automatically using the Auto Disk feature. This feature copies the Fig.6: movable cursors provide detailed measurement information. The cursors can even be set to automatically find zero crossing points. contents of live memory to disk after each complete record acquisition. With careful setup of the trigger system, this feature could be used to wait for and capture unusual signal excursions, such as the dreaded glitch! A limitation with the naming of Auto Disk files allows a maximum of only 999 files to be created in a single session (the last three digits of filenames are automatically assigned numbers 1 - 999). This is not a problem for most applications but seems an unnecessary limitation nevertheless. Accurate measurements A variety of useful measurements can be made quickly and easily by using mouse-moveable cursors. These are enabled from the Cursors pull-down menu and once enabled, a dialog box appears, listing all the Saving settings & waveforms The good news is that once you’ve got the instruments set up the way 80 Silicon Chip Fig.7: comparing a previously acquired signal (shown in red) with a live signal. If desired, the reference signal can be automatically scaled to match the live signal. Fig.8: example hardcopy output. We sent our output to a Postscript file rather than a real printer, allowing us to import it into just about any application. measurements made at the current cursor positions (see Fig.6) Reference memory OK, so we said that the record length (memory depth) is 32K, but the specs table (see Table 1) lists 64K – where’d the other half go? As we mentioned earlier, digital ‘scopes usually contain reference memory - an area of memory that is used to temporarily store a copy of live memory for comparative purposes. Clicking the “Copy to Ref” button on the toolbar transfers a copy of the current live memory contents to Fig.9: the voltmeter alone could make the TiePie Handyprobe an indispensable instrument for all service personnel. reference memory (also called the reference channel). Clicking on the “Ref1” button displays the reference channel (see Fig.7) along with the current live channel, if active. shape and colour are customisable, too. As shown in our example, a longer (up to 3 line) comment can also be added to the top right of the printout. Hard copy As with all the other instruments in the package, TiePie have done their best to make the voltmeter as functional as possible. Data is presented to the user in a similar manner to a conventional digital voltmeter (DVM), and includes triple displays with bargraphs (see Fig.9). The input signal can be either AC or DC coupled, with a range of between 0.5 and 400V full scale. Autoranging is also supported. Each display is independently configurable via the Settings pull-down menu. Measurements can be made in true RMS, peak-to-peak, mean, maximum, minimum, dBm, power, crest, frequency, duty cycle or moment value (see Fig.10). Amps, Kilograms, Degrees C and Watts are just a sample of the various Units of measure that can be selected to ease the strain on the grey matter. And of course, displayed values can be scaled to suit by changing the Units per measurement unit value. Quick “go-no go” tests can be made by configuring the Set high value and Set low value entries appropriately. This function is also useful for monitoring a signal for out-of-range conditions, depending on how the sound settings (see Fig.11) are configured. To reduce the obvious duplication of settings between instruments, Tie- A faithful copy of the displayed waveform can be made at any time by using the Print feature (see Fig.8). Comments can be added anywhere on the display area with the aid of user-definable comment balloons. Balloons can have arrows that point wherever you like (see our “Clipping” balloon example on Fig.3). Balloon Fig.10: all three of the voltmeter displays are independently configurable. And you can store all your favourite settings on disk. Voltmeter JUNE 2000 81 Fig.12: Measurements can be made at intervals of between 1 and 300 seconds, with the results stored on disk or sent to the printer. Fig.11: testing between limits is made easier with audible feedback. Here we can set the actual tones used and select either PC speaker or sound card as the playback device. Pie have slaved many of the settings together. For example, the voltmeter actually uses the record length and post-trigger samples from the oscilloscope. If either the oscilloscope or spectrum analyser is active though, their settings override the voltmeter settings as the voltmeter has lowest priority. The frequency range setting is an exception to this rule, as changing it in the voltmeter affects all other instruments. TiePie have included a “use scope frequency” setting to avoid potential frustration! The voltmeter takes 200 samples of the input signal at the selected frequency range for each measurement. Without going into any detail, we note that the selected range is critical to obtaining an accurate measurement. An Auto frequency option has been included on the Settings menu that eliminates the guesswork. In common with all other instru- ments, the voltmeter can be set to either measure continuously or perform one-shot measurements at the press of a button. An addition recording function on this instrument allows measurements to be made at intervals of between 1 and 300 seconds, with the results stored on disk. This function is configured from the Acquisition pull-down menu (see Fig.12). Spectrum analyser If you work with filters, amplifiers, oscillators, mixers, modulators, or detectors, you need a spectrum analyser. Whereas oscilloscopes display signals in the time domain (which is fine for determining amplitude, time and phase information) spectrum analysers display signals in the frequency domain. The frequency domain contains certain information that is just not Fig.13: the spectrum analyser instrument really expands the usefulness of the package. 82 Silicon Chip visible in the time domain. To borrow several examples from the Handyprobe user manual: 1. A sine wave may look good in the time domain, but in the frequency domain harmonic distortion is visible. 2. A noise signal may look totally random in the time domain, but in the frequency domain one frequency may be dominantly present. 3. In the frequency domain it is easy to determine carrier frequency, modulation frequency, modulation level and modulation distortion from an AM or FM signal. Fig.13 shows what a 200kHz square wave looks like on the spectrum analyser. Square waves are (theoretically) composed of an infinite number of harmonics, some of which you can see on the left and right of the 200kHz peak. Without going into complicated explanations, suffice to say that the Handyprobe software uses Fast Fourier Transforms (FFT) to calculate the spectral components of the sampled signal. Errors are introduced during this conversion process, and by using one of several FFT windowing techniques selectable from the Settings pull- Fig.14: TiePie have included important window functions for the spectrum analyser. Fig.15: Don’t like the type of horizontal axis offered? Change it! down menu these can be reduced to a minimum (see Fig.14). Vertical axis With two exceptions, all vertical axis settings are the same as on the oscilloscope instrument. In fact, key settings such as sensitivity and triggering are slaved between instruments to make setup a little easier. Of course, they can also be individually controlled if necessary. The spectrum analyser instrument adds an option for either a linear (volts) or logarithmic (decibels) vertical axis scale, and removes the Units of measure option. Horizontal axis The frequency axis pull-down menu provides access to all horizontal axis settings. In a similar manner to the oscilloscope, both the sampling frequency and record length can be set here. Also of interest is the Axis Type setting (see Fig.15). Measuring harmonics An important feature of this instrument is its ability to measure Total Harmonic Distortion (THD). This is set up and displayed from the Measure pull-down menu. The number of harmonics used to calculate the THD is user definable and the results can be displayed in decibels or as a percentage (see Fig.16). As with the oscilloscope, cursors are provided for easy waveform measurement (see Fig.17). A multitude of other features match those that we have already described for the oscilloscope in- Fig.16: to measure THD, simply set the number of strument. These in- harmonics to use in the calculations and hit the “go” lude display zoom- button. ing, signal averaging, copying live to used also mean that other instruments reference memory, saving waveforms cannot be active when the transient to disk, hardcopy output and saving/ recorder is active. restoring instrument settings. Many features of this instrument are common to those found on the Transient recorder oscilloscope and spectrum analyser, If you need to measure slowly so we’ll concentrate mainly on the changing signals over a period of unique ones here. time, the transient recorder is the Recording speed instrument of choice (see Fig.18). Unlike the other instruments in Sampling time can be set anywhere the package, the transient recorder from 0.01 second to 500 seconds (see is direct registering. This means that Fig.19), with a complete record variait displays each measurement as it ble from 1 to 32,760 samples. is made, rather than waiting for an The recording process can be inentire record to be acquired. This terrupted at any time and the results is necessary because at the lowest saved to disk or printed. It is also sample rate, it can take up to 189.6 possible to have the recorder run days to fill a record! The different measurement and display techniques Fig.17: once again, the cursor readout makes measurements easy. Fig.18: the transient recorder instrument. Here we’ve used the Units of measure and Units of gain settings to simulate a thermocouple reading in thousands of °C. JUNE 2000 83 an arbitrary waveform generator (AWG) instrument. Software for the TiePieSCOPE is practically identical to the Handyprobe, notwithstanding the additional support for the second channel and the AWG. We’ve included a screen shot of the AWG just to wet your appetite (see Fig.20)! Where to get more information – and it! Fig.19: setting the transient recorder measure speed. continuously and automatically save to disk at the end of each complete record acquisition. Note that at very high measuring speeds, TiePie state that some data samples may be lost due to the overhead of disk access. During recording, the display can be set to roll left as the trace reaches the rightmost edge of the screen – a great feature that reminds me of mechanical chart recorders with their drums and pens. Data gathered from the recorder will most often be used for documentation purposes, so the vertical axis customisation features really shine in this instrument. Pre-defined choices for the units of measure include Volt, Amp, Degree C, Degree F, Watt, Percent, Meter, Kilogram, Newton, Coulomb, Bar and Hertz. If you can’t find what you want in that lot you can define your own in five characters or less. Text balloons of variable shape, size and colour can be positioned anywhere on the display, and colour printer output is supported, too! A sample rate of at least 10 times the signal frequency is widely accepted as the minimum that is required to provide reasonable signal reconstruction, which means that the useable bandwidth of the oscilloscope and spectrum analyser (for the 20M samples/sec version) is around 2MHz under most conditions. Need more speed? If the Handyprobe 2 sounds great but you need more bandwidth or another channel, TiePie also offer the TiePieSCOPE HS801. This instrument is not quite as portable as the Handyprobe, but it adds a second channel, has five times the sample rate (100M samples/sec) and includes Hardware specifications Table 1 lists the key Handyprobe 2 hardware specifications. The input resolution is listed as 8 bits, 0.39%, with an accuracy of 1% ± 1 LSB. The sample rate used to measure any signal must be at least twice its frequency to prevent false readings (called “aliasing”). This rule applies to all the instruments except the transient recorder. 84 Silicon Chip Fig.20: here’s a glimpse of the TiePie HandyProbe’s “big brother”, the $2450 HandyScope and (inset) its arbitrary waveform generator. Self-running demos and complete user manuals for the Handyprobe 2 and TiePieSCOPE are available for free download from Tiepie’s web site at www.tiepie.nl. Our review unit came from the Australian distributors of TiePie Engineering products,Melbourne-based RTN, phone/fax (03) 9338 3306; email nollet<at>enternet.com.au. Pricing The 10MHz TiePie HP2 (as reviewed) currently has a recommended price of $740 including sales tax. A 20MHz version sells for $810. Note that these prices are almost certain to change next month with the introduction of the GST but also due to currency fluctuations. Current prices are based on $AU1=$US0.6 but at press time the Aussie dollar had fallen below that rate and the chances are it will go lower. A phone call to RTN will give you the latest pricing. The TiePie HP2 carries a 12 month warranty and most servicing is carSC ried out locally. Own an EFI car? Want to get the best from it? Youll find all you need to know in this publication LAST CHANCE ORDER BEFORE JUNE NEW NEW NEW NEW AUDIO POWER AM DESIGN HANDBOOK INDUSTRIAL BRUSHLESS SERVOMOTORS From one of the world’s most respected audio authorities. The new 2nd edition is even more comprehensive, includes sections on load-invariant power amps, distortion residuals, diagnosis of amplifier problems, and much more. 368 pages in paperback. Designed as a guide for professionals and a module text for electrical and mechanical engineering students. A step-by-step approach covering construction, how they work, how the motor behaves and how it is rated and selected. 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Published 1997. $ 9295 $ NEW NEW NEW NEW 5995 $ Your Name_________________________________________________ PLEASE PRINT Address ___________________________________________________ ___________________________________ Postcode_______________ Daytime Phone No. (______) __________________________________ STD Email___________________<at>_________________________________  Cheque/Money Order enclosed OR  Charge my credit card –  Bankcard  Visa Card  MasterCard Signature____________________Card expiry date PLUS P&P (if applic): $.............. _ TOTAL$ AU.................... ALL TITLES SUBJECT TO AVAILABILITY. PRICES VALID UNTIL 30 JUNE 2000 ONLY. PRICES DO NOT INCLUDE GST E BEFORE GST! E 30 AND SAVE $10% WANT TO SAVE ANOTHER 10%? SILICON CHIP SUBSCRIBERS AUTOMATICALLY QUALIFY FOR A 10% DISCOUNT ON ALL BOOK PURCHASES! (To subscribe, see page 65) UNDERSTANDING TELEPHONE ELECTRONICS THE ART OF LINEAR ELECTRONICS By Stephen J. Bigelow. 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Widely regarded as the standard text on EMC, this book provides all the information necessary to meet the requirements of the EMC Directive. It includes chapters on standards, measurement techniques and design principles, including layout and grounding, digital and analog circuit design, filtering and shielding and interference sources. The four appendices give a design checklist and include useful tables, data and formulae. 299 pages, in soft cover at $95.00. 95 $ Add $A5.00 per book – Orders over $100 P&P free in Australia. NZ: Add $A10 per book, $A15 elsewhere 24 95 $ DIGITAL ELECTRONICS– A PRACTICAL APPROACH $ By Eugene Trundle. First published 1988. Second edition 1996. 55 P&P 80 By Lilian Hobbs. First published 1996. Second edition 1999. Eugene Trundle has written for many years in Television magazine and his latest book is right up to date on TV and video technology. The book includes both theory and practical servicing information and is ideal for both students and technicians. 382 pages, in paperback, at $55.00. $ $ This practical handbook from one of the world’s most prolific audio designers has been updated and amended to make it the leading practical source of information for those interested in linear electronics and its applications, particularly in the world of audio design. 348 pages, in paperback, at $80.00. DESIGNING INTERNET HOME PAGES MADE SIMPLE AUDIO ELECTRONICS By John Linsley Hood. First published 1993. NEW SECOND EDITION 1998. Provides all the information and software that is necessary for a PC user to install and use the freeware Linux operating system. It details, setp-by-step, how to obtain and configure the operating system and utilities. It also explains all of the key commands. The text is generously illustrated with screen shots and examples that show how the commands work. Includes a CDROM containing Linux version 1.3 and including all the interim updates, basic utilities and compilers with their associated documentation. 257 pages, in paperback, at $85.00. 85 $ POST TO: SILICON CHIP Publications, PO Box 139, Collaroy NSW, Australia 2097. OR CALL (02) 9979 5644 & quote your credit card details; or FAX TO (02) 9979 6503 JUNE 2000 87 Silicon Chip Back Issues August 1992: Automatic SLA Battery Charger; Miniature 1.5V To 9V DC Converter; 1kW Dummy Load Box For Audio Amplifiers; Troubleshooting Vintage Radio Receivers; The MIDI Interface Explained. October 1992: 2kW 24VDC - 240VAC Sinewave Inverter; Multi-Sector Home Burglar Alarm, Pt.2; Mini Amplifier For Personal Stereos; A Regulated Lead-Acid Battery Charger. January 1993: Flea-Power AM Radio Transmitter; High Intensity LED Flasher For Bicycles; 2kW 24VDC To 240VAC Sinewave Inverter, Pt.4; Speed Controller For Electric Models, Pt.3. September 1988: Hands-Free Speakerphone; Electronic Fish Bite Detector; High-Performance AC Millivoltmeter, Pt.2; Build The Vader Voice. December 1990: 100W DC-DC Converter For Car Amplifiers; Wiper Pulser For Rear Windows; 4-Digit Combination Lock; 5W Power Amplifier For The 6-Metre Amateur Transmitter; Index To Volume 3. April 1989: Auxiliary Brake Light Flasher; What You Need to Know About Capacitors; 32-Band Graphic Equaliser, Pt.2; The Story Of Amtrak Passenger Services. January 1991: Fast Charger For Nicad Batteries, Pt.1; Have Fun With The Fruit Machine; Two-Tone Alarm Module; LCD Readout For The Capacitance Meter; How Quartz Crystals Work; The Dangers of Servicing Microwave Ovens. May 1989: Build A Synthesised Tom-Tom; Biofeedback Monitor For Your PC; Simple Stub Filter For Suppressing TV Interference; The Burlington Northern Railroad. July 1989: Exhaust Gas Monitor; Experimental Mains Hum Sniffers; Compact Ultrasonic Car Alarm; The NSW 86 Class Electrics. February 1991: Synthesised Stereo AM Tuner, Pt.1; Three Low-Cost Inverters For Fluorescent Lights; Low-Cost Sinewave Oscillator; Fast Charger For Nicad Batteries, Pt.2; How To Design Amplifier Output Stages. September 1989: 2-Chip Portable AM Stereo Radio (Uses MC13024 and TX7376P) Pt.1; High Or Low Fluid Level Detector; Studio Series 20-Band Stereo Equaliser, Pt.2. March 1991: Remote Controller For Garage Doors, Pt.1; Transistor Beta Tester Mk.2; A Synthesised AM Stereo Tuner, Pt.2; Multi-Purpose I/O Board For PC-Compatibles; Universal Wideband RF Preamplifier For Amateur Radio & TV. October 1989: FM Radio Intercom For Motorbikes Pt.1; GaAsFet Preamplifier For Amateur TV; 2-Chip Portable AM Stereo Radio, Pt.2; A Look At Australian Monorails. April 1991: Steam Sound Simulator For Model Railroads; Remote Controller For Garage Doors, Pt.2; Simple 12/24V Light Chaser; Synthesised AM Stereo Tuner, Pt.3; A Practical Approach To Amplifier Design, Pt.2. November 1989: Radfax Decoder For Your PC (Displays Fax, RTTY & Morse); FM Radio Intercom For Motorbikes, Pt.2; 2-Chip Portable AM Stereo Radio, Pt.3; Floppy Disk Drive Formats & Options; The Pilbara Iron Ore Railways. May 1991: 13.5V 25A Power Supply For Transceivers; Stereo Audio Expander; Fluorescent Light Simulator For Model Railways; How To Install Multiple TV Outlets, Pt.1. January 1990: High Quality Sine/Square Oscillator; Service Tips For Your VCR; Phone Patch For Radio Amateurs; Active Antenna Kit; Designing UHF Transmitter Stages. July 1991: Loudspeaker Protector For Stereo Amplifiers; 4-Channel Lighting Desk, Pt.2; How To Install Multiple TV Outlets, Pt.2; Tuning In To Satellite TV, Pt.2. February 1990: A 16-Channel Mixing Desk; Build A High Quality Audio Oscillator, Pt.2; The Incredible Hot Canaries; Random Wire Antenna Tuner For 6 Metres; Phone Patch For Radio Amateurs, Pt.2. September 1991: Digital Altimeter For Gliders & Ultralights; Ultrasonic Switch For Mains Appliances; The Basics Of A/D & D/A Conversion; Plotting The Course Of Thunderstorms. March 1990: Delay Unit For Automatic Antennas; Workout Timer For Aerobics Classes; 16-Channel Mixing Desk, Pt.2; Using The UC3906 SLA Battery Charger IC; The Australian VFT Project. October 1991: Build A Talking Voltmeter For Your PC, Pt.1; SteamSound Simulator For Model Railways Mk.II; Magnetic Field Strength Meter; Digital Altimeter For Gliders, Pt.2; Military Applications Of R/C Aircraft. April 1990: Dual Tracking ±50V Power Supply; Voice-Operated Switch (VOX) With Delayed Audio; 16-Channel Mixing Desk, Pt.3; Active CW Filter; Servicing Your Microwave Oven. June 1990: Multi-Sector Home Burglar Alarm; Build A Low-Noise Universal Stereo Preamplifier; Load Protector For Power Supplies; Speed Alarm For Your Car. July 1990: Digital Sine/Square Generator, Pt.1 (covers 0-500kHz); Burglar Alarm Keypad & Combination Lock; Build A Simple Electronic Die; A Low-Cost Dual Power Supply; Inside A Coal Burning Power Station. August 1990: High Stability UHF Remote Transmitter; Universal Safety Timer For Mains Appliances (9 Minutes); Horace The Electronic Cricket; Digital Sine/Square Generator, Pt.2. September 1990: A Low-Cost 3-Digit Counter Module; Build A Simple Shortwave Converter For The 2-Metre Band; The Bose Lifestyle Music System (Review); The Care & Feeding Of Nicad Battery Packs (Getting The Most From Nicad Batteries). November 1991: Build A Colour TV Pattern Generator, Pt.1; A Junkbox 2-Valve Receiver; Flashing Alarm Light For Cars; Digital Altimeter For Gliders, Pt.3; Build A Talking Voltmeter For Your PC, Pt.2; Build a Turnstile Antenna For Weather Satellite Reception. December 1991: TV Transmitter For VCRs With UHF Modulators; Infrared Light Beam Relay; Colour TV Pattern Generator, Pt.2; Index To Volume 4. January 1992: 4-Channel Guitar Mixer; Adjustable 0-45V 8A Power Supply, Pt.1; Baby Room Monitor/FM Transmitter; Experiments For Your Games Card. March 1992: TV Transmitter For VHF VCRs; Thermostatic Switch For Car Radiator Fans; Coping With Damaged Computer Directories; Guide Valve Substitution In Vintage Radios. February 1993: Three Projects For Model Railroads; Low Fuel Indicator For Cars; Audio Level/VU Meter (LED Readout); An Electronic Cockroach; 2kW 24VDC To 240VAC Sinewave Inverter, Pt.5. March 1993: Solar Charger For 12V Batteries; Alarm-Triggered Security Camera; Reaction Trainer; Audio Mixer for Camcorders; A 24-Hour Sidereal Clock For Astronomers. April 1993: Solar-Powered Electric Fence; Audio Power Meter; Three-Function Home Weather Station; 12VDC To 70VDC Converter; Digital Clock With Battery Back-Up. June 1993: AM Radio Trainer, Pt.1; Remote Control For The Woofer Stopper; Digital Voltmeter For Cars; Build A Windows-Based Logic Analyser. July 1993: Single Chip Message Recorder; Light Beam Relay Extender; AM Radio Trainer, Pt.2; Quiz Game Adjudicator; Windows-Based Logic Analyser, Pt.2; Antenna Tuners – Why They Are Useful. August 1993: Low-Cost Colour Video Fader; 60-LED Brake Light Array; Microprocessor-Based Sidereal Clock; Southern Cross Z80-Based Computer; A Look At Satellites & Their Orbits. September 1993: Automatic Nicad Battery Charger/Discharger; Stereo Preamplifier With IR Remote Control, Pt.1; In-Circuit Transistor Tester; +5V to ±15V DC Converter; Remote-Controlled Cockroach. October 1993: Courtesy Light Switch-Off Timer For Cars; Wireless Microphone For Musicians; Stereo Preamplifier With IR Remote Control, Pt.2; Electronic Engine Management, Pt.1. November 1993: High Efficiency Inverter For Fluorescent Tubes; Stereo Preamplifier With IR Remote Control, Pt.3; Siren Sound Generator; Engine Management, Pt.2; Experiments For Games Cards. December 1993: Remote Controller For Garage Doors; Build A LED Stroboscope; Build A 25W Audio Amplifier Module; A 1-Chip Melody Generator; Engine Management, Pt.3; Index To Volume 6. January 1994: 3A 40V Variable Power Supply; Solar Panel Switching Regulator; Printer Status Indicator; Mini Drill Speed Controller; Stepper Motor Controller; Active Filter Design; Engine Management, Pt.4. February 1994: Build A 90-Second Message Recorder; 12-240VAC 200W Inverter; 0.5W Audio Amplifier; 3A 40V Adjustable Power Supply; Engine Management, Pt.5; Airbags In Cars – How They Work. March 1994: Intelligent IR Remote Controller; 50W (LM3876) Audio Amplifier Module; Level Crossing Detector For Model Railways; Voice Activated Switch For FM Microphones; Engine Management, Pt.6. April 1994: Sound & Lights For Model Railway Level Crossings; Discrete Dual Supply Voltage Regulator; Universal Stereo Preamplifier; Digital Water Tank Gauge; Engine Management, Pt.7. May 1994: Fast Charger For Nicad Batteries; Induction Balance Metal Locator; Multi-Channel Infrared Remote Control; Dual Electronic Dice; Simple Servo Driver Circuits; Engine Management, Pt.8. April 1992: IR Remote Control For Model Railroads; Differential Input Buffer For CROs; Understanding Computer Memory; Aligning Vintage Radio Receivers, Pt.1. June 1994: 200W/350W Mosfet Amplifier Module; A Coolant Level Alarm For Your Car; 80-Metre AM/CW Transmitter For Amateurs; Converting Phono Inputs To Line Inputs; PC-Based Nicad Battery Monitor; Engine Management, Pt.9. October 1990: The Dangers of PCBs; Low-Cost Siren For Burglar Alarms; Dimming Controls For The Discolight; Surfsound Simulator; DC Offset For DMMs; NE602 Converter Circuits. May 1992: Build A Telephone Intercom; Electronic Doorbell; Battery Eliminator For Personal Players; Infrared Remote Control For Model Railroads, Pt.2; Aligning Vintage Radio Receivers, Pt.2. July 1994: Build A 4-Bay Bow-Tie UHF Antenna; PreChamp 2-Transistor Preamplifier; Steam Train Whistle & Diesel Horn Simulator; Portable 6V SLA Battery Charger; Electronic Engine Management, Pt.10. November 1990: Connecting Two TV Sets To One VCR; Build An Egg Timer; Build A Low-Cost Model Train Controller; 1.5V To 9V DC Converter; Introduction To Digital Electronics; A 6-Metre Amateur Transmitter. June 1992: Multi-Station Headset Intercom, Pt.1; Video Switcher For Camcorders & VCRs; IR Remote Control For Model Railroads, Pt.3; 15-Watt 12-240V Inverter; A Look At Hard Disk Drives. August 1994: High-Power Dimmer For Incandescent Lights; Microprocessor-Controlled Morse Keyer; Dual Diversity Tuner For FM Microphones, Pt.1; Nicad Zapper (For Resurrecting Nicad Batteries); Engine Management, Pt.11. ORDER FORM Please send thethe following back issues: Please send following back issues: ____________________________________________________________ Enclosed is my cheque/money order for $______or please debit my: ❏ Bankcard ❏ Visa Card ❏ Master Card Signature ___________________________ Card expiry date_____ /______ Name ______________________________ Phone No (___) ____________ PLEASE PRINT Street ______________________________________________________ Suburb/town _______________________________ Postcode ___________ 88 Silicon Chip Note: prices include postage & packing Australia ....................... $A7.70 (incl. GST) Overseas (airmail) ............................ $A10 ✂ Card No. Detach and mail to: Silicon Chip Publications, PO Box 139, Collaroy, NSW, Australia 2097. Or call (02) 9979 5644 & quote your credit card details or fax the details to (02) 9979 6503. Email: silchip<at>siliconchip.com.au September 1994: Automatic Discharger For Nicad Battery Packs; MiniVox Voice Operated Relay; Image Intensified Night Viewer; AM Radio For Weather Beacons; Dual Diversity Tuner For FM Microphones, Pt.2; Engine Management, Pt.12. November 1996: Adding A Parallel Port To Your Computer; 8-Channel Stereo Mixer, Pt.1; Low-Cost Fluorescent Light Inverter; How To Repair Domestic Light Dimmers; Build A Multi-Media Sound System, Pt.2; 600W DC-DC Converter For Car Hifi Systems, Pt.2. October 1994: How Dolby Surround Sound Works; Dual Rail Variable Power Supply; Build A Talking Headlight Reminder; Electronic Ballast For Fluorescent Lights; Build A Temperature Controlled Soldering Station; Electronic Engine Management, Pt.13. December 1996: Active Filter Cleans Up CW Reception; Fast Clock For Railway Modellers; Laser Pistol & Electronic Target; Build A Sound Level Meter; 8-Channel Stereo Mixer, Pt.2; Index To Volume 9. December 1998: Protect Your Car With The Engine Immobiliser Mk.2; Thermocouple Adaptor For DMMs; A Regulated 12V DC Plugpack; Build Your Own Poker Machine, Pt.2; Improving AM Radio Reception, Pt.2; Mixer Module For F3B Glider Operations. November 1994: Dry Cell Battery Rejuvenator; Novel Alphanumeric Clock; 80-Metre DSB Amateur Transmitter; Twin-Cell Nicad Discharger (See May 1993); How To Plot Patterns Direct to PC Boards. January 1997: How To Network Your PC; Control Panel For Multiple Smoke Alarms, Pt.1; Build A Pink Noise Source (For Sound Level Meter Calibration); Computer Controlled Dual Power Supply, Pt.1; Digi-Temp Monitors Eight Temperatures. January 1999: The Y2K Bug & A Few Other Worries; High-Voltage Megohm Tester; Getting Going With BASIC Stamp; LED Bargraph Ammeter For Cars; Keypad Engine Immobiliser; Improving AM Radio Reception, Pt.3; Electric Lighting, Pt.10 December 1994: Dolby Pro-Logic Surround Sound Decoder, Pt.1; Easy-To-Build Car Burglar Alarm; Three-Spot Low Distortion Sinewave Oscillator; Clifford – A Pesky Electronic Cricket; Remote Control System for Models, Pt.1; Index to Vol.7. February 1997: Cathode Ray Oscilloscopes, Pt.6; PC-Controlled Moving Message Display; Computer Controlled Dual Power Supply, Pt.2; Alert-A-Phone Loud Sounding Alarm; Control Panel For Multiple Smoke Alarms, Pt.2. January 1995: Sun Tracker For Solar Panels; Battery Saver For Torches; Dolby Pro-Logic Surround Sound Decoder, Pt.2; Dual Channel UHF Remote Control; Stereo Microphone Preamplifier. March 1997: Driving A Computer By Remote Control; Plastic Power PA Amplifier (175W); Signalling & Lighting For Model Railways; Build A Jumbo LED Clock; Cathode Ray Oscilloscopes, Pt.7. February 1999: Installing A Computer Network (Network Types, Hubs, Switches & Routers); Making Front Panels For Your Projects; Low Distortion Audio Signal Generator, Pt.1; Command Control Decoder For Model Railways; Build A Digital Capacitance Meter; Remote Control Tester; Electric Lighting, Pt.11. February 1995: 50-Watt/Channel Stereo Amplifier Module; Digital Effects Unit For Musicians; 6-Channel Thermometer With LCD Readout; Wide Range Electrostatic Loudspeakers, Pt.1; Oil Change Timer For Cars; Remote Control System For Models, Pt.2. April 1997: Simple Timer With No ICs; Digital Voltmeter For Cars; Loudspeaker Protector For Stereo Amplifiers; Model Train Controller; A Look At Signal Tracing; Pt.1; Cathode Ray Oscilloscopes, Pt.8. March 1995: 50 Watt Per Channel Stereo Amplifier, Pt.1; Subcarrier Decoder For FM Receivers; Wide Range Electrostatic Loudspeakers, Pt.2; IR Illuminator For CCD Cameras; Remote Control System For Models, Pt.3; Simple CW Filter. April 1995: FM Radio Trainer, Pt.1; Photographic Timer For Darkrooms; Balanced Microphone Preamp. & Line Filter; 50W/Channel Stereo Amplifier, Pt.2; Wide Range Electrostatic Loudspeakers, Pt.3; 8-Channel Decoder For Radio Remote Control. May 1997: Teletext Decoder For PCs; Build An NTSC-PAL Converter; Neon Tube Modulator For Light Systems; Traffic Lights For A Model Intersection; The Spacewriter – It Writes Messages In Thin Air; A Look At Signal Tracing; Pt.2; Cathode Ray Oscilloscopes, Pt.9. June 1997: PC-Controlled Thermometer/Thermostat; Colour TV Pattern Generator, Pt.1; Build An Audio/RF Signal Tracer; High-Current Speed Controller For 12V/24V Motors; Manual Control Circuit For A Stepper Motor; Cathode Ray Oscilloscopes, Pt.10. May 1995: Build A Guitar Headphone Amplifier; FM Radio Trainer, Pt.2; Transistor/Mosfet Tester For DMMs; A 16-Channel Decoder For Radio Remote Control; Introduction to Satellite TV. July 1997: Infrared Remote Volume Control; A Flexible Interface Card For PCs; Points Controller For Model Railways; Simple Square/ Triangle Waveform Generator; Colour TV Pattern Generator, Pt.2; An In-Line Mixer For Radio Control Receivers. June 1995: Build A Satellite TV Receiver; Train Detector For Model Railways; 1W Audio Amplifier Trainer; Low-Cost Video Security System; Multi-Channel Radio Control Transmitter For Models, Pt.1. August 1997: The Bass Barrel Subwoofer; 500 Watt Audio Power Amplifier Module; A TENs Unit For Pain Relief; Addressable PC Card For Stepper Motor Control; Remote Controlled Gates For Your Home. July 1995: Electric Fence Controller; How To Run Two Trains On A Single Track (Incl. Lights & Sound); Setting Up A Satellite TV Ground Station; Build A Reliable Door Minder. September 1997: Multi-Spark Capacitor Discharge Ignition; 500W Audio Power Amplifier, Pt.2; A Video Security System For Your Home; PC Card For Controlling Two Stepper Motors; HiFi On A Budget; Win95, MSDOS.SYS & The Registry. August 1995: Fuel Injector Monitor For Cars; Gain Controlled Microphone Preamp; Audio Lab PC-Controlled Test Instrument, Pt.1; How To Identify IDE Hard Disk Drive Parameters. September 1995: Railpower Mk.2 Walkaround Throttle For Model Railways, Pt.1; Keypad Combination Lock; The Vader Voice; Jacob’s Ladder Display; Audio Lab PC-Controlled Test Instrument, Pt.2. October 1995: Geiger Counter; 3-Way Bass Reflex Loudspeaker System; Railpower Mk.2 Walkaround Throttle For Model Railways, Pt.2; Fast Charger For Nicad Batteries; Digital Speedometer & Fuel Gauge For Cars, Pt.1. November 1995: Mixture Display For Fuel Injected Cars; CB Transverter For The 80M Amateur Band, Pt.1; PIR Movement Detector; Dolby Pro Logic Surround Sound Decoder Mk.2, Pt.1; Digital Speedometer & Fuel Gauge For Cars, Pt.2. December 1995: Engine Immobiliser; 5-Band Equaliser; CB Transverter For The 80M Amateur Band, Pt.2; Subwoofer Controller; Dolby Pro Logic Surround Sound Decoder Mk.2, Pt.2; Knock Sensing In Cars; Index To Volume 8. January 1996: Surround Sound Mixer & Decoder, Pt.1; Magnetic Card Reader; Build An Automatic Sprinkler Controller; IR Remote Control For The Railpower Mk.2; Recharging Nicad Batteries For Long Life. March 1996: Programmable Electronic Ignition System; Zener Diode Tester For DMMs; Automatic Level Control For PA Systems; 20ms Delay For Surround Sound Decoders; Multi-Channel Radio Control Transmitter; Pt.2; Cathode Ray Oscilloscopes, Pt.1. April 1996: Cheap Battery Refills For Mobile Telephones; 125W Audio Power Amplifier Module; Knock Indicator For Leaded Petrol Engines; Multi-Channel Radio Control Transmitter; Pt.3; Cathode Ray Oscilloscopes, Pt.2. May 1996: Upgrading The CPU In Your PC; High Voltage Insulation Tester; Knightrider Bi-Directional LED Chaser; Simple Duplex Intercom Using Fibre Optic Cable; Cathode Ray Oscilloscopes, Pt.3. June 1996: BassBox CAD Loudspeaker Software Reviewed; Stereo Simulator (uses delay chip); Rope Light Chaser; Low Ohms Tester For Your DMM; Automatic 10A Battery Charger. July 1996: Installing a Dual Boot Windows System On Your PC; Build A VGA Digital Oscilloscope, Pt.1; Remote Control Extender For VCRs; 2A SLA Battery Charger; 3-Band Parametric Equaliser; Single Channel 8-bit Data Logger. August 1996: Electronics on the Internet; Customising the Windows Desktop; Introduction to IGBTs; Electronic Starter For Fluorescent Lamps; VGA Oscilloscope, Pt.2; 350W Amplifier Module; Masthead Amplifier For TV & FM; Cathode Ray Oscilloscopes, Pt.4. September 1996: VGA Oscilloscope, Pt.3; IR Stereo Headphone Link, Pt.1; High Quality PA Loudspeaker; 3-Band HF Amateur Radio Receiver; Cathode Ray Oscilloscopes, Pt.5. October 1996: Send Video Signals Over Twisted Pair Cable; Power Control With A Light Dimmer; 600W DC-DC Converter For Car Hifi Systems, Pt.1; IR Stereo Headphone Link, Pt.2; Build A Multi-Media Sound System, Pt.1; Multi-Channel Radio Control Transmitter, Pt.8. Machine, Pt.1; FM Transmitter For Musicians; Lab Quality AC Millivoltmeter, Pt.2; Setting Up A LAN Using TCP/IP; Understanding Electric Lighting, Pt.9; Improving AM Radio Reception, Pt.1. March 1999: Getting Started With Linux; Pt.1; Build A Digital Anemometer; 3-Channel Current Monitor With Data Logging; Simple DIY PIC Programmer; Easy-To-Build Audio Compressor; Low Distortion Audio Signal Generator, Pt.2; Electric Lighting, Pt.12. April 1999: Getting Started With Linux; Pt.2; High-Power Electric Fence Controller; Bass Cube Subwoofer; Programmable Thermostat/ Thermometer; Build An Infrared Sentry; Rev Limiter For Cars; Electric Lighting, Pt.13; Autopilots For Radio-Controlled Model Aircraft. May 1999: The Line Dancer Robot; An X-Y Table With Stepper Motor Control, Pt.1; Three Electric Fence Testers; Heart Of LEDs; Build A Carbon Monoxide Alarm; Getting Started With Linux; Pt.3. June 1999: FM Radio Tuner Card For PCs; X-Y Table With Stepper Motor Control, Pt.2; Programmable Ignition Timing Module For Cars, Pt.1; Hard Disk Drive Upgrades Without Reinstalling Software; What Is A Groundplane Antenna?; Getting Started With Linux; Pt.4. July 1999: Build The Dog Silencer; A 10µH to 19.99mH Inductance Meter; Build An Audio-Video Transmitter; Programmable Ignition Timing Module For Cars, Pt.2; XYZ Table With Stepper Motor Control, Pt.3; The Hexapod Robot. August 1999: Remote Modem Controller; Daytime Running Lights For Cars; Build A PC Monitor Checker; Switching Temperature Controller; XYZ Table With Stepper Motor Control, Pt.4; Electric Lighting, Pt.14; DOS & Windows Utilities For Reversing Protel PC Board Files. October 1997: Build A 5-Digit Tachometer; Add Central Locking To Your Car; PC-Controlled 6-Channel Voltmeter; 500W Audio Power Amplifier, Pt.3; Customising The Windows 95 Start Menu. September 1999: Automatic Addressing On TCP/IP Networks; Wireless Networking Without The Hassles; Autonomouse The Robot, Pt.1; Voice Direct Speech Recognition Module; Digital Electrolytic Capacitance Meter; XYZ Table With Stepper Motor Control, Pt.5; Peltier-Powered Can Cooler. November 1997: Heavy Duty 10A 240VAC Motor Speed Controller; Easy-To-Use Cable & Wiring Tester; Build A Musical Doorbell; Relocating Your CD-ROM Drive; Replacing Foam Speaker Surrounds; Understanding Electric Lighting Pt.1. October 1999: Sharing A Modem For Internet & Email Access (WinGate); Build The Railpower Model Train Controller, Pt.1; Semiconductor Curve Tracer; Autonomouse The Robot, Pt.2; XYZ Table With Stepper Motor Control, Pt.6; Introducing Home Theatre. December 1997: Build A Speed Alarm For Your Car; Two-Axis Robot With Gripper; Loudness Control For Car Hifi Systems; Stepper Motor Driver With Onboard Buffer; Power Supply For Stepper Motor Cards; Understanding Electric Lighting Pt.2; Index To Volume 10. November 1999: USB – Hassle-Free Connections TO Your PC; Electric Lighting, Pt.15; Setting Up An Email Server; Speed Alarm For Cars, Pt.1; Multi-Colour LED Christmas Tree; Build An Intercom Station Expander; Foldback Loudspeaker System For Musicians; Railpower Model Train Controller, Pt.2. January 1998: Build Your Own 4-Channel Lightshow, Pt.1 (runs off 12VDC or 12VAC); Command Control System For Model Railways, Pt.1; Pan Controller For CCD Cameras; Build A One Or Two-Lamp Flasher; Understanding Electric Lighting, Pt.3. February 1998: Hot Web Sites For Surplus Bits; Multi-Purpose Fast Battery Charger, Pt.1; Telephone Exchange Simulator For Testing; Command Control System For Model Railways, Pt.2; Build Your Own 4-Channel Lightshow, Pt.2; Understanding Electric Lighting, Pt.4. April 1998: Automatic Garage Door Opener, Pt.1; 40V 8A Adjustable Power Supply, Pt.1; PC-Controlled 0-30kHz Sinewave Generator; Build A Laser Light Show; Understanding Electric Lighting; Pt.6; Jet Engines In Model Aircraft. May 1998: Troubleshooting Your PC, Pt.1; Build A 3-LED Logic Probe; Automatic Garage Door Opener, Pt.2; Command Control For Model Railways, Pt.4; 40V 8A Adjustable Power Supply, Pt.2. December 1999: Internet Connection Sharing Using Hardware; Electric Lighting, Pt.16; Index To Volume 12; Build A Solar Panel Regulator; The PC Powerhouse (gives fixed +12V, +9V, +6V & +5V rails); The Fortune Finder Metal Locator; Speed Alarm For Cars, Pt.2; Railpower Model Train Controller, Pt.3. January 2000: Spring Reverberation Module; An Audio-Video Test Generator; Build The Picman Programmable Robot; A Parallel Port Interface Card; Off-Hook Indicator For Telephone Lines; B&W Nautilus 801 Monitor Loudspeakers (Review). February 2000: Build A Multi-Sector Sprinkler Controller; A Digital Voltmeter For Your Car; An Ultrasonic Parking Radar; Build A Safety Switch Checker; A Sine/Square Wave Oscillator For Your Workbench; Marantz SR-18 Home Theatre Receiver (Review); The “Hot Chip” Starter Kit (Review). June 1998: Troubleshooting Your PC, Pt.2; Understanding Electric Lighting, Pt.7; Universal High Energy Ignition System; The Roadies’ Friend Cable Tester; Universal Stepper Motor Controller; Command Control For Model Railways, Pt.5. March 2000: Doing A Lazarus On An Old Computer; Ultra Low Distortion 100W Amplifier Module, Pt.1; Electronic Wind Vane With 16-LED Display; Glowplug Driver For Powered Models; The OzTrip Car Computer, Pt.1; Multisim Circuit Design & Simulation Package (Review). July 1998: Troubleshooting Your PC, Pt.3 (Installing A Modem And Sorting Out Problems); Build A Heat Controller; 15-Watt Class-A Audio Amplifier Module; Simple Charger For 6V & 12V SLA Batteries; Automatic Semiconductor Analyser; Understanding Electric Lighting, Pt.8. April 2000: A Digital Tachometer For Your Car; RoomGuard – A Low-Cost Intruder Alarm; Build A Hot wire Cutter; The OzTrip Car Computer, Pt.2; Build A Temperature Logger; Atmel’s ICE 200 In-Circuit Emulator; How To Run A 3-Phase Induction Motor From 240VAC. August 1998: Troubleshooting Your PC, Pt.4 (Adding Extra Memory To Your PC); Build The Opus One Loudspeaker System; Simple I/O Card With Automatic Data Logging; Build A Beat Triggered Strobe; A 15-Watt Per Channel Class-A Stereo Amplifier. September 1998: Troubleshooting Your PC, Pt.5 (Software Problems & DOS Games); A Blocked Air-Filter Alarm; A Waa-Waa Pedal For Your Guitar; Build A Plasma Display Or Jacob’s Ladder; Gear Change Indicator For Cars; Capacity Indicator For Rechargeable Batteries. October 1998: CPU Upgrades & Overclocking; Lab Quality AC Millivoltmeter, Pt.1; PC-Controlled Stress-O-Meter; Versatile Electronic Guitar Limiter; 12V Trickle Charger For Float Conditions; Adding An External Battery Pack To Your Flashgun. November 1998: The Christmas Star (Microprocessor-Controlled Christmas Decoration); A Turbo Timer For Cars; Build A Poker May 2000: Building the Ultra-LD Stereo Amplifier, Pt.2; Build A LED Dice (With PIC Microcontroller); A Low-Cost AT Keyboard Translator (Converts IBM Scan-Codes To ASCII); 50A Motor Speed Controller For Models; Dolby Headphone – Five Channels Of Surround Sound; What’s Inside A Furby. PLEASE NOTE: November 1987 to August 1988, October 1988 to March 1989, June 1989, August 1989, December 1989, May 1990, June 1991, August 1991, February 1992, July 1992, September 1992, November 1992, December 1992, May 1993 and March 1998 are now sold out. All other issues are presently in stock. For readers wanting articles from sold-out issues, we can supply photostat copies (or tear sheets) at $7.00 per article (includes p&p). When supplying photostat articles or back copies, we automatically supply any relevant notes & errata at no extra charge. A complete index to all articles published to date is available on floppy disk for $10 including p&p, or can be downloaded free from our web site: www.siliconchip.com.au JUNE 2000 89 ASK SILICON CHIP Got a technical problem? Can’t understand a piece of jargon or some technical principle? Drop us a line and we’ll answer your question. Write to: Ask Silicon Chip, PO Box 139, Collaroy Beach, NSW 2097. How to vary spring reverb time I have built two of the reverb units described in the January 2000 issue into a single enclosure for my band co-member and we are quite impressed with the performance. The only issue we have is that for vocal use, the reverb length is too long, thereby muddying the sound. Is there a simple mod which will address this problem ? I guess what I’m after is a “reverb duration” control. (J. S., via email). • The reverb delay is fixed by the springs and cannot be adjusted easily. You could try reducing the length of the springs but that brings the risk of permanently damaging the unit. Optical fibre project suggestions There is a lot of debate at present regarding mobile phone radiation. Even the hands-free kits are suspected of channelling radiation into the ear and possibly being worse than not using them. How about a project which uses a fibre link between the phone and the hands-free earpiece How to avoid blowing the bass barrel I’m presently building my second Bass Barrel subwoofer (as described in the August 1997 issue) but this time I’m making it from MDF board. Why? Cos I blew the first one up! And since I had put it all together with Liquid Nails there was not much chance of pulling it apart to change the drivers! I drove the original one with one channel of a stereo integrated amp (at least 120W into 4Ω) and I think it was a bit much! What is the nominal rating of the barrel? And what size amplifier module would you suggest? 90 Silicon Chip and microphone? With no wires there would be nothing to conduct the RF emissions. I realise there would be challenges with power and size but I’m sure something could be achieved. (I suppose a cheaper option is to put a ferrite choke in the cable somehow.) A related project suggestion is for a fibre-optic stereo transmitter/receiver. For example, my CDs are in the house but I’m doing some work in the shed. Wouldn’t it be great to be able to listen to them there? I figure a fibre-optic cable from the house to the shed, an appropriate transmitter plugged into the amplifier (line-out probably), a receiver in the shed plugged into a second amplifier (line-in). There would then be no worries with earth loops or long speaker cables or induced noise, etc A neat extra (which would considerably increase the cost no doubt) would be to make it duplex so that using a remote control in the shed, I could control the CD player which is in the house (similar to what you can do with B&O gear which I would love to own but cannot afford). And how about an opto-isolator for modem lines so that they don’t have to be unplugged from the modem every time it looks like a storm? (M. B., via email). • It does seem possible that the lead for the hands-free mobile phone kit could act as a “counterpoise” and thereby contribute to stronger radiation of the mobile signal. An optical fibre solution would be tricky and would require a separate battery supply as well. Your alternative suggestion of a choke in the lead could be a simple and effective solution. As far as your CD player is concerned, the most effective solution would be to use its optical output (if it has one) and feed it to a D/A converter in your shed. However, while it could be done, the cost is likely to be more than the price of a portable CD player – you can buy them for around $125 now. And as far as an optical isolator for phone lines is concerned, it would only remove the lightning protection issue from the modem to the isolator; after all, the isolator would still need a mains supply and it is the potential difference between the phone lines and the mains supply which blows modems. I have built the Altronics sub-woofer controller as well and would like to build a small amplifier inside it to make it a self-contained unit. I am thinking of using the 50W stereo module described in the February 1995 issue and then using one channel to drive each speaker as the Altronics controller can provide in-phase and out-of-phase outputs. I would rather have the amplifier a bit too big than too small. (D. A., via email). • We would suggest that you feed no more than 50W into the Bass Barrel system. If you drive each speaker with 50W you will blow it for sure. I am currently upgrading my hifi system and I am looking at upgrading to a surround sound system. As a kit builder I am wondering if SILICON CHIP is going to do a decoder for Dolby analog, digital or other in the near future, or whether this sort of technology is beyond the scope of a kit. I have had a look for the “Dolby Pro Logic Surround Sound Decoder Mk.2” kits but have been unable to source this particular project. (D. H., via email). • Our last Dolby project was in November & December 1995 and the project has now been discontinued. Since then Dolby decoders have dropped markedly in price and so another Dolby decoder project would not be viable. Dolby decoder kit wanted Speed control won’t regulate Could you please help me with a problem with the motor speed control published in the June 1997 issue? I purchased a kit and had no trouble with it until I damaged it (my fault). Rather than spend time fixing it, I purchased another kit and built it. However, it won’t regulate more than a couple of volts. In the test sheet they show pin 16 of the IC at +12V but in the circuit diagram it shows pin 16 grounded; the other readings seem close. Can you help please? (J. D., via email). • Pin 16 of IC1 should be at ground as shown on the circuit. The mention of pin 16 being at 12V is a misprint and should say that pin 12 is at 12V. You can test the circuit by measuring voltages. There should be +12V at pin 12, +5V at pins 14 & 15. Check that there is not a short between the drain and source pins of the Mosfets Q3 and Q4. Pin 13 of IC1 should be at ground. Check also that the voltage at the wiper of VR1 can be adjusted from 0V to 5V. Data logger interface I am looking for a data logger to connect to the anemometer kit published in the March 1999 issue of SILICON CHIP. I bought and built a data logger kit (2V - 20V input) but need a way to read the pulses emitted from the reed switch on the anemometer into a frequency with an analog output so that I can take a sample every hour or so. The reason for this is that I am involved in a student assignment to collect wind speed data from a site to gauge its suitability for a wind generator. I thought some sort of frequency counter with an analog output (meter) would do but have been unable to find one that reads pulses into frequency so far. (D. D., via email). • The anemometer comprises a reed switch activated by a rotating magnet. A frequency meter does actually convert the pulses applied to its input into a frequency measurement. It does this by counting the pulses over a set period of time of, for example, one second. This would mean that the number of pulses is the frequency in Spring reverb sounds dead I have purchased and constructed a Spring Reverb as described in the January 2000 issue of SILICON CHIP. Generally, I found that the spring reverb effect is subjectively quite good and ‘sweet’ sounding. However, there seems to be a serious problem with the unit when used for my purposes. I play a guitar through the unit (guitar into input of unit, output of unit to amplifier input) and have found that I get a “dead” sound from the unit; my guitar seems to lose highs and dynamics. Note that this occurs even when I turn the reverb effect off which means that I am only really going through the final op amp/mixer. I have checked the frequency response of the unit with some test equipment (pink noise source and 1/3-octave band analyser) and have found it to be very good, as specified in the article. The guitar frequency range doesn’t really go above 10kHz so I cannot see how this would be a problem. Given this, I cannot explain why the unit Hz. So you do not need a unit to convert the pulses from the reed switch into a frequency which is then applied to the analog frequency meter. We would suggest using the National Semiconductor LM2917 chip to do the whole conversion for you. It will convert the pulses from the reed switch into a voltage. We used an LM2917 in the Gear Change Alarm published in the September 1998 issue of S ILICON CHIP and the values used in that circuit would probably suit your application. Data for the device can be obtained from the National Semiconductor linear data book or search the web for data from the National Semiconductor site. Knight Rider LEDs don’t switch direction I built the Knight Rider from the May 1996 issue and it’s not switching direction. I see that the circuit diagram shows pins 5 & 6 on IC 3 at sounds like it is cutting out highs and making the guitar sound dead. I can only assume that it has something to do with the transient/dynamic response of the unit. The guitar is a very dynamic instrument; when you hit the strings hard you get sparkly loud highs. Possibly, it is something to do with mismatched input or output impedances. Note that the pickups in my guitar have something like 10kΩ output impedance. Is there anything you can suggest which might help me out? Note also that I have found some information on this type of spring reverb on a website at http://members.tripod.com/~roymal/reverb. htm (J. A., via email). • The dead sound from your Spring Reverb module could be due to the loading effect of the level pot VR1. Check that it is actually 50kΩ in value. If it is not high enough, it could cause problems. You could also use a 100kΩ type instead. Also try changing the .0039µF capacitor value to something smaller. +12V but the PC board ties them to pins 3 & 8 and they are all at ground. Please explain. (S. D., via email). • The J and K inputs to IC3 are shown tied high on the circuit but they are actually tied low on the PC board. This has no effect on the circuit operation. However, you are on the right track to finding the problem with your Knightrider circuit, since it is the IC3 flipflop which changes the direction of the LEDs. Check your board for shorts between tracks, particularly near IC3. Check also that each LED is inserted with the correct polarity, particularly the LEDs at each end. The outputs driving these end LEDs at pin 11 and pin 15 of IC4 switch the flipflop (IC3) so the direction changes on each LED sweep. Flexible I/O cards for PCs I am building the I/O interface kit that was published in the July 1997 JUNE 2000 91 Snubber burnout in fluorescent inverter I have built and operated two of the high efficiency inverters for fluorescent lamps, published in the October 1993 issue. They have operated for the past 18 months but in January this year the 22Ω resistor in the snubber circuit went up in smoke at turn on. I did no more than take the fitting apart to fix it and it still works. In November I bought three more of these kits and assembled two, with the 22Ω resistor in one lasting only a few hours and it no longer works. The other now refuses to go after not being used for a couple of weeks. These later kits use a different toroidal core (T2) to the previous ones and they run very hot; ie, burn issue. However, there seems to be problem with getting the input from the hardware. Could it be because of the program (Basic listing) problem? I followed all the instructions and I can use the output part of the hardware with success. (H. H., via email). • If the relays can be operated from the computer listing, then the address selection for IC1 would appear to be correct. The same address selection is used for the reading of data at the IC3 and optocoupler inputs. So therefore the software appears to run correctly. Perhaps you have a problem on the PC board. Check that diodes D1-D8 are installed the correct way around and that the optocouplers are working. A low on an input should select a high at the corresponding collector output of the optocoupler. This volt- your fingers. Up until this stage I have been impressed with their performance. Can you advise? (M. F., via email). • The 22Ω resistor in the snubber could be changed to a 0.5W rating if you find that it does not last past 18 months of use. Your later kits with a different toroid for T2 are not likely to work properly since the characteristics of this core determine how the circuit operates. Unless the toroid has the same saturation and inductance factor, the oscillator frequency will not be consistent with the design. This will alter the frequency of drive to the fluorescent tube and alter the tube current. We can only recommend the RCC12.5/7.5/5 3F3 ring core for T2 as described in the parts list. age should also be at the respective Data input (D0-D7) of IC3. Is there a hazard with leaded solder? Of late my doctor friend passed me an article concerning the health hazard of workers in industry doing soldering work. The article covers lead poisoning. As we know solder contains lead. In most cases it is 40 percent lead and 60 percent tin. I have the following questions in mind. Is there a risk involving soldering work? The fumes released from soldering generally contains flux. Do the fumes also contain lead vapour with it? My guess is there isn’t since lead is a heavy metal. The only thing we MUST remember to do is after soldering work is to wash our hands clean, to prevent contamination when we handle food. To be safe why don’t we switch to using lead free solder? I found leadfree cored solder has 99.3 percent tin and 0.7 percent copper alloy. It has a melting point of 227°C. Dick Smith Electronics have it available (Cat N-1628). Will the electrical joints using this type of solder be as good as 60/40 tin/lead alloy solder? I found solder joints using lead free solder to be not as shiny. Why is this so? Is it because tin is not as shiny as lead? Is this effect just cosmetic or does it have an effect on the tensile strength of the soldered joints? One way to test this is to solder a piece of cable to a copper base and use a strain gauge to test the pull strength of the solder joints. Have you experimented with this sort of test? Finally, has SILICON CHIP published an article in regard to the risk involving soldering work? (M. O., via email). • We have not done an article on the risks of lead in solder and we are inclined to the view that they are very low. It seems that the main reason for the push for lead-free solder comes from Europe where they want to keep lead out of community land-fills. Furthermore, we have the view that lead in solder is probably as much a health risk as lead in dental amalgam (ie, extremely low). Most dentists don’t believe amalgam is a risk. Having said that, you should use a fan to blow the fumes away while soldering; depending on how hot your soldering iron is, there could be some lead in the vapour and yes, you should definitely wash your hands after soldering. We have not done any work involvSC ing lead-free solder. WARNING! SILICON CHIP magazine regularly describes projects which employ a mains power supply or produce high voltage. All such projects should be considered dangerous or even lethal if not used safely. Readers are warned that high voltage wiring should be carried out according to the instructions in the articles. When working on these projects use extreme care to ensure that you do not accidentally come into contact with mains AC voltages or high voltage DC. If you are not confident about working with projects employing mains voltages or other high voltages, you are advised not to attempt work on them. Silicon Chip Publications Pty Ltd disclaims any liability for damages should anyone be killed or injured while working on a project or circuit described in any issue of SILICON CHIP magazine. 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. SILICON CHIP also disclaims any liability for projects which are used in such a way as to infringe relevant government regulations and by-laws. Advertisers are warned that they are responsible for the content of all advertisements and that they must conform to the Trade Practices Act 1974 or as subsequently amended and to any governmental regulations which are applicable. 92 Silicon Chip DON’T UTER COMP MISS OMNIBUS THE ’BUS! www.siliconchip.com.au SILICON CHIP’S 132 Pages 9 $ 95 * ISBN 0 95852291 X 780958 522910 IN LINCLUDES FEA U TUR X E A collection of computer features from the pages of SILICON CHIP magazine Hints o Tips o Upgrades o Fixes Covers DOS, Windows 3.1, 95, 98, NT o RT Do you feel a little “left behind” by the latest advances and developments in computer hardware and software? Don’t miss the bus: get the ’bus! THIS IS IT: The computer reference you’ve been asking for! SILICON CHIP's Computer Omnibus is a valuable compendium of the most-requested computer hardware and software features from recent issues of SILICON CHIP magazine - all in one handy volume. Here's just a sample of the contents: Troubleshooting your PC: what to do when things go wrong NO Choosing, installing and taming computer networks AVA W Upgrading and overclocking CPUs DIRE ILABLE C Hard disk drive upgrades, tune-ups and tips SILIC T FROM Windows 3.1, 95, 98 and NT tips and tricks ON just $ CHIP The Y2K Bug - and how to swat it 125O* INC All about Linux GST & P& P And much more!!! ORDER NOW: Use the handy order form in this issue or call (02) 9979 5644, 9-5 Mon-Fri with your credit card details. * Price includes GST 09 9780958522910 09 9 MARKET CENTRE Cash in your surplus gear. Advertise it here in Silicon Chip. FRWEEBE YES! Place your classified advertisement in SIL- ICON CHIP Market Centre and your advert will also appear FREE in the Classifieds-on-the-Web page of the SILICON CHIP website, www.siliconchip.com.au And if you include an email address or your website URL in you classified advert, the links will be LIVE in your classified-on-the-web! S! D E I F I S C LAS EXCLUSIVE TO SILICON CHIP! CLASSIFIED ADVERTISING RATES Advertising rates for this page: Classified ads: $11.00 (incl. GST) for up to 12 words plus 55 cents for each additional word. Display ads: $27.50 (incl. GST) per column centimetre (max. 10cm). Closing date: five weeks prior to month of sale. To run your classified ad, print it clearly in the space below or on a separate sheet of paper, fill out the form & send it with your cheque or credit card details to: Silicon Chip Classifieds, PO Box 139, Collaroy, NSW 2097. Or fax the details to (02) 9979 6503. Taxation Invoice ABN 49 003 205 490 _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ Enclosed is my cheque/money order for $__________ or please debit my ❏ Bankcard ❏ Visa Card ❏ Master Card Card No. Signature ________________________ Card expiry date______/______ Name _____________________________________________________ Street _____________________________________________________ Suburb/town _________________________ Postcode______________ 94 Silicon Chip FOR SALE RAIN BRAIN AND DIGI-TEMP KITS: 8 station sprinkler controllers, 60 channel temp monitor uses DS1820s over 500 metres. Has PC Data logging. Mantis Micro Products, http://www.home.aone.net.au/mantismp ELECTRONIC/MECHANICAL DESIGN AND CONSTRUCTION: we offer a complete design service for electronic and mechanical devices. Most work is done in house and you deal directly with the designers. No job is too small and can be to prototype or “turn key” stage, in one offs or for future production. Simply send us an email at vladimir<at> u030.aone.net.au with your questions or requirements and we will get back to you. WEATHER STATIONS: Windspeed & direction, inside temperature, outside temperature & windchill. Records highs & lows with time and date as they occur. $420.00 complete plus sales tax if appli cable. Optional rainfall and PC interface. Used by Government Departments, farmers, pilots, and weather enthusiasts. Other models with barometric pressure, humidity, dew point, solar radiation, UV, leaf wetness, etc. Just phone, fax or write for our FREE catalogue and price list. Solar Flair/Ecowatch ph: (03) 5968 4863 fax: (03) 5968 5810, PO Box 18, Emerald, Vic., 3782. ACN 006 399 480. KITS KITS AND MORE KITS! Check ‘em out at www.ozitronics.com PCBs for all older magazine projects can be obtained from 0408-613-300 or http://www.cia.com.au/rcsradio C COMPILERS: everything you need to develop C and ASM software for 68HC08, 6809, 68HC11, 68HC12, 68 HC16, 8051/52, 8080/85, 8086, 8096 or AVR: $155.00 each. Macro Cross Assemblers and Disassemblers for above CPUs + 6800/01/03/05, 6502 and 68HC12 for $78. Debug monitors: $78 for 6 CPUs. All compilers, XASMs and monitors: $480. 8051/52 Simulator (fast, now incl. 80C320): $78. Try the C-FLEA Virtual Machine for small CPUs, build a “C-Stamp”. Demo desk: FREE. All prices + $5 p&p. Atmel Flash CPU Programmer: Handles the 89Cx051, 89C5x and 89Sxx series, and the new AVRs in both DIP and PLCC44. Also does most 8-pin EEPROMs. Includes socket for serial ISP cable. $199, $37 tax, $10 p&p. SOIC adaptors: 20-pin $90, 14-pin $85, 8-pin $80. Credit cards accepted. GRAN TRONICS PTY LTD, PO Box 275, Wentworthville 2145. Ph (02) 9896 7150; Fax (02) 9631 1236; or Internet: http://www.grantronics.com.au LOWER G$T PRICES from June 1 ! DON’T wait until JULY ! Visit allthings.com.au for LOWER G$T prices. BULLET CAMERAS $110 with 2 YEAR WARRANTY * Mono DOME CAMERAS 420 Line $63 * 380 Line $92 * 450 Line $117 with 5 YEAR WARRANTY & BLEMISH FREE CCD * with SONY CCD $95 * COLOUR DOME CAMERAS 420 Line $90 * 400 Line DSP $177 * 450 Line $186 * 440 Line $215 with 5 YEAR WARRANTY & BLEMISH FREE CCD * 600 Line DSP $201 * PINHOLE MODULE IN PIR DETECTOR $144 * COLOUR DSP PIN PCB in PIR CASE $189 * MINI 36 mm x 36 mm $87 * 420 Line $108 with 5 YEAR WARRANTY & BLEMISH FREE CCD * DSP COLOUR $172 * FOUR Channel Switchers $101 * QUAD 1024 x 512 $226 * COLOUR QUAD $520 * Auto / Manual Scanners $147 * REMOTE PAN & TILT $311 * VIDEO TRANSMITTERS $160 * TRANSMITTER BOOSTERS $180 * MULTIPLEXER 4 Ch $829 * DIGITAL PC VIDEO RECORDING SOFTWARE & PCI CARD $119 * PROFESSIONAL REMOTE DIAL-UP & PAGING SOFTWARE & PCI CARD $249 * REMOTE STANDALONE DIAL-IN/OUT Systems (no PC required) from $899 * PINHOLE PCB MODULES $77 * COLOUR DSP $169 * DIY PLUG-IN 20 metre AV Cable & Adaptor Sets suit all Cameras from $30 * PLUS LOTS of NEW PRODUCTS * LOWER PRICES * UP TO 5 YEARS WARRANTY * VISIT: allthings.com.au NOW ! T: 08 9349 9413. SOLAR PANELS: 120 watt $995.00, 80 watt $650.00, 60 watt $510.00, 40 watt $395.00 (all with 25 year guarantee). UNBREAKABLE PANELS: ROLA Australia (08) 8270 3175 www.bettanet.net.au/GTD Silvertone’s RC Receiver Still the best little performer available! MP3-CD Player: $699 Plays standard CDs & MP3s as well. Plays MP3 CDs made with a CD writer. Up to 2200 songs per CD. Car adapter available. ROLA 15U & 15UX: $325 Size: 15" (380mm). Freqency response: 30-3,000Hz (15U); 30-12,000Hz (15UX). Power handling: 250 watts RMS. SPL: 97db/1 metre. FS (resonant frequency) 30Hz. Satellite TV Reception International satellite TV reception in your home is now affordable. Send for your free info pack containing equipment catalog, satellite lists, etc or call for appointment to view. We can display all satellites from 76.5° to 180°. Still only $129.50 AM or $149.50 FM. May be used with most ppm transmitters. This and many other radio control products available from: Silvertone Electronics, PO Box 580, Riverwood 2210. Phone/Fax (02) 9533 3517. www.silvertone.com.au AV-COMM P/L, 24/9 Powells Rd, Brookvale, NSW 2100. Tel: 02 9939 4377 or 9939 4378. Fax: 9939 4376; www.avcomm.com.au Need prototype PC boards? We have the solutions – we print electronics! Four-day turnaround, less if urgent; Artwork from your own positive or file; Through hole plating; Prompt postal service; 29 years technical experience; Inexpensive; Superb quality. Printed Electronics, 12A Aristoc Rd, Glen Waverley, Vic 3150. Phone: (03) 9545 3722; Fax: (03) 9545 3561 Call Mike Lynch and check us out! We are the best for low cost, small runs. Positions At Jaycar We are often looking for enthusiastic staff for positions in our retail stores and head office at Rhodes in Sydney. A genuine interest in electronics is a necessity. Phone 02 9743 5222 for current vacancies. 64 watt $550.00, 42 watt $420.00, 32 watt $340.00, 11 watt $190.00, 5 watt $120.00, 1.25 watt $80.00. WIND GENERATORS: 400 watt $950.00. INVERTERS: sinewave inverters, inverter/chargers, mod. Sinewave inverters, call with requirements. AUSTRALIA WIDE DELIVERY (Free on orders over $500.00). TASMAN ENERGY: (03) 6362 3050 Fax (03) 6362 3054. tronic equipment. Free delivery. Order now: 0410 739 317. RAINBOW POWER COMPANY – Solar Panels 80W $595, Batteries, Inverters, Regulators, Rebates Available – call (02) 6689 1430. PERSON WITH EXPERIENCE / APTITUDE able to fault find & repair PCBs – without diagrams. GENEROUS PKG NEG. Tel John<at>AER (03) 9482 4958 0415 305 470. CAMERAS TOP QUALITY - DIY PAK 4 COLOUR Cameras, Switcher, Power SPECIAL $785 – Colour Camera/ AUDIO $159 – Colour DOME $159 – WATERPROOF camera $189 – NIGHT-VISION camera $120 – WIRELESS transmitter $65 – Bug detector $245. Best prices on security & elec- KIT ASSEMBLY ANY KITS assembled/repaired: professional, speedy service. Phone Neville Walker (07) 3857 2752. WANTED Circuit Ideas Wanted Do you have a good circuit idea? We pay up to $60 for contributions to Circuit Notebook. Silicon Chip Publications, PO Box 139, Collaroy, 2097. JUNE 2000 95 Silicon Chip Binders Keep your copies safe, secure and always available with SILICON CHIP binders: they’re cheap insurance! Advertising Index REAL VALUE AT $12.95 PLUS P &P  Heavy board covers with 2-tone green vinyl covering Altronics................................. 74-76 Av-Comm Pty Ltd.........................95 Dick Smith Electronics........... 10-13 Electronic Valve & Tube Co..........55  Each binder holds up to 14 issues so that you can include catalogs EMC Technologies.......................37  SILICON CHIP logo printed in gold-coloured lettering on spine & cover Harbuch Electronics....................35 Emona Instruments...................IBC Instant PCBs................................95 Jaycar ................................... 45-52 Price: $12.95 plus $5 p&p each (available Aust. only) Kalex............................................41 Order by phoning (02) 9979 5644 & quoting your credit card number; or fax the details to (02) 9979 6503; or mail your order with cheque or credit card details to Silicon Chip Publications, PO Box 139, Collaroy, NSW 2097. Kits-R-Us.....................................95 Microgram Computers...................3 MicroZed Computers...................37 Oatley Electronics........................25 DON’T MISS THE ’BUS Do you feel left behind by the latest advances in computer technology? Don’t miss the bus: get the ’bus! Includes articles on troubleshooting your PC, installing and setting up computer networks, hard disk drive upgrades, clean installing Windows 98, CPU upgrades, a basic introduction to Linux plus much more. Optional Power..........................IFC www.siliconchip.com.au SILICON CHIP’S 132 Pages 9 $ 95 * ISBN 0 95852291 X 09 9780958522910 09 9 780958 522910 COMPUTER OMNIBUS IN LI CLUDE FEA NU S TUR X E A collection of computer features from the pages of SILICON CHIP magazine Printed Electronics...................... 95 Questronix...................................37 Rall Electronics............................37 REC Electronics......................OBC Robotoz.......................................37 Rocom Electronics.......................37 R.T.N............................................33 Hints o Tips o Upgrades o Fixes Covers DOS, Windows 3.1, 95, 98, NT NO W o AVA DIRE ILABLE C SILIC T FROM ON just $ CHIP 125O INC ORDER NOW: Use the handy order form in this issue or call (02) 9979 5644, 8.30-5.30 Mon-Fri with your credit card details. Silicon Chip Back Issues....... 88-89 Silicon Chip Binders....................96 RT P&P Note: price does not include GST which applies from 1st July, 2000. Silicon Chip Bookshop........... 86-87 SC Computer Omnibus...............93 Silicon Chip Subscriptions...........34 Silvertone Electronics..................95 HELP SAVE THE NIGHT SKY! We are losing our heritage of starry night skies. Poor, inefficient outdoor lighting is causing glare and “light pollution”. This wastes energy and increases greenhouse gas emissions. You can help by joining SYDNEY OUTDOOR LIGHTING IMPROVEMENT SOCIETY (SOLIS). SOLIS aims to educate and inform about quality outdoor lighting and its benefits. We also lobby councils, government and other bodies to promote good lighting practice. SOLIS meetings are held third Monday night of each month at Sydney Observatory. Individual membership is $20 pa. Donations are also welcome. Cheques payable to “SOLIS c/- NSAS”, PO Box 214, West Ryde 2114. Email: tpeters<at>pip.elm.mq.edu.au 96 Silicon Chip Solar Flair/Ecowatch....................94 Vass Electronics..........................37 _____________________________ PC Boards Printed circuit boards for SILICON CHIP projects are made by: • RCS Radio Pty Ltd. Phone 0408- 613-300. • Marday Services, PO Box 19-189, Avondale, Auckland, NZ. Phone (09) 828 5730. SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.emona.com.au