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SILICON Australia’s World-Class Electronics Magazine! UNWIRED: CHIP WIRELESS BROADBAND HAS ARRIVED! NOVEMBER 2004 ISSN 1030-2662 11 9 771030 266001 7 $ 90* NZ $ 8 75 INC GST INC GST PRINT POST APPROVED -PP255003/01272 3-STAGE AUTOMATIC BATTERY CHARGER DRIVEWAY SENTRY - Magnetic field sensor siliconchip.com.au November 2004  1 USB-UP - USB-controlled 240V power switch 42V ELECTRICS - the future of vehicle power SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings.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 Contents Vol.17, No.11; November 2004 www.siliconchip.com.au FEATURES 8 Look Mum: No Wires Want broadband Internet access without waiting for an ADSL or cable connection? “Unwired” does it without fuss – by Ross Tester 20 The New Era In Car Electrical Systems The first cars using 42V batteries are now being released. Find out what’s behind the move to higher voltages – by Julian Edgar 94 Emergency Power When All Else Fails Is this one of Stan’s wind-ups? You’d better believe it . . . just wind the handle for some emergency battery charging – by Stan Swan Look Mum; No Wires For HassleFree Broadband – Page 8. PROJECTS TO BUILD 28 USB-Controlled Power Switch Build this and automatically power up all your PC’s peripherals when you start the computer. It works via the PC’s USB port – by Jim Rowe 34 A Charger For Deep-Cycle 12V Batteries, Pt.1 That’s not a charger . . . this is a charger! If you want to charge deep-cycle 12V batteries correctly, this 16.6A unit is the way to go – by John Clarke 66 The Driveway Sentry Detect vehicles coming down your driveway and automatically open gates or sound an alarm with this reliable unit. It works just like the detectors used for traffic-lights – by Jim Rowe USB-Controlled Power Switch – Page 28. 74 SMS Controller, Pt.2 Second article tells you how to complete the circuit checks and describes how the unit is used – by Peter Smith 90 Picaxe Infrared Remote Control Here’s how to add infrared remote control to all your PICAXE-08M projects (including Rudolph) – by Clive Seager SPECIAL COLUMNS 80 Circuit Notebook (1) Low-Coolant Alarm For Falcon EF & EL Models; (2) One-Second Darkroom Ticker; (3) Simpler PC Power-Up; (4) Micro Timer With LED Readout; (5) Water Pump Monitor; (6) Reducing The Effective Mains Voltage 44 Serviceman’s Log It’s time I bought a new TV set – by the TV Serviceman 96 Vintage Radio 12V 16.6A Charger For Deep-Cycle Batteries – Page 34. Those troublesome capacitors, Pt.2 – by Rodney Champness DEPARTMENTS 2 4 65 87 89 Publisher’s Letter Mailbag Order Form Product Showcase Silicon Chip Weblink siliconchip.com.au 106 109 110 112 Ask Silicon Chip Notes & Errata Market Centre Ad Index Driveway Sentry – Page 66. November 2004  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 Editor Peter Smith Technical Staff John Clarke, B.E.(Elec.) Ross Tester Jim Rowe, B.A., B.Sc, VK2ZLO Reader Services Ann Jenkinson Advertising Enquiries Phil Benedictus Laurence Smith Benedictus Smith Pty Ltd Phone (02) 9211 9792 Fax: (02) 9211 0068 info<at>benedictus-smith.com Regular Contributors Brendan Akhurst Rodney Champness, VK3UG Julian Edgar, Dip.T.(Sec.), B.Ed Mike Sheriff, B.Sc, VK2YFK Stan Swan 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. Printing: Hannanprint, Noble Park, Victoria. Distribution: Network Distribution Company. Subscription rates: $83.00 per year in Australia. For overseas rates, see the subscription page in this issue. 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 Fixed line phones no longer a necessity This month’s feature story on “Unwired” internet access must worry anyone who has Telstra shares. Why? Because Telstra’s customers no longer need a fixed line telephone service to obtain internet access. Up till now, if you wanted internet access, whether dial-up via a 56K modem or an ADSL broadband service, you had to have a fixed line telephone service. The exceptions would be if you had cable TV, in which case you could have a cable modem for internet or you might have used a satellite internet service. For the vast majority of people though, a fixed line telephone was a necessity. Of course, if you don’t need internet access and you already have a mobile phone, you have not needed a fixed line telephone service for some time. In fact, tens of thousands of people living in rented accommodation throughout Australia have long ago opted not to bother with a fixed line service. In doing so, they avoid installation charges which are hard to justify, since they normally only require a few minutes work by a technician at the local exchange. They also avoid monthly rental charges, high STD phone charges and so on. For a person who makes very few phone calls, a prepaid mobile is definitely the way go. There are no rental charges, you only pay for the calls you make and incoming calls are free. Why bother with a fixed line telephone? This is a world-wide trend, with the number of mobile phones rapidly exceeding the number of fixed line installations. In fact, many developing countries look to be leap-frogging the large infrastructure cost of fixed lines and just adopting mobile phone services instead. In Australia, one could foresee a situation where most private individuals do not have fixed line phones – they would be confined to businesses and organisations. And then you have to factor in the concept of “Voice over IP” as described in last month’s issue – for virtually any telephone calls. Large businesses are already migrating to VOIP for long distance calls and small business and private individuals will largely follow in the future. So even if they keep their fixed line telephone systems, they will be using VOIP and ADSL to cut their long-distance phone costs. All of which does not augur well for Telstra. It has an enormous investment in its fixed line network in which it has a monopoly. But it doesn’t have a monopoly in mobile phones where it is being buffeted by intense competition by some very aggressive players. So unless there is some new development which encourages customers to take up more services involving fixed line telephones, one can only see Telstra’s fixed line revenues being severely eroded in the future. Sooner or later, and probably sooner, the investment pundits will realise this and the shares will go down accordingly. This is yet another example of the inexorable march of technology. At one time, steam engines and horseless carriages had a very big market but they fizzled to nothing. What can Telstra do? In the short term, it might like to buy Unwired Australia! Leo Simpson * Recommended and maximum price only. 2  Silicon Chip siliconchip.com.au MicroGram 8dBi Wireless LAN Antenna Best range! Better price! Top quality! Perfect for increasing the signal from an access point. Provides a suitable antenna for an access point in Infrastructure mode or Point to Multi Point mode. It is an 8dB, vertically polarised designed to operate in the 2.4GHz range. It has a 50 ohm passive feed and has a Type N female connector. Cat 11430-7 $139 Voice Activated Remote SATA Controller Add SATA drives to your PC. Cat 2872-7 $99 Issue voice commands to any device that uses an infrared remote control Cat 9180-7 $239 “It’s transfer speeds were almost uniformly excellent and remarkably consistent” PDA Keyboard Adapter Switch your standard keyboard between PDA and PC mode. Cat 9229-7 $69 PC User magazine August 2004 USB Net Phone Luminescent Keyboard This 105 key keyboard has a remarkably soft, even, luminescent back light. Cat 1008171-7 $79 Extend USB 50m Use any USB device up to 50m from a PC over inexpensive UTP cable (not included) Cat 11666-7 $105 Make free PC to PC calls, and calls to landline phones world-wide at ridiculously low rates over your internet connection. Cat 10129-7 $89 Front Access Bay Two Port KVM with Sound This 5¼" bay has USB 2.0, FireWire, Power Out, Audio In/Out and a 6 in 1 memory card reader. Cat 6765-7 $129 Allows one keyboard, monitor, and mouse to control two PCs. Includes 1.2m cables. Cat 11669-7 $139 Front Access Video Editing USB 2.0 TV Box 12.1" LCD Monitor Watch TV on your laptop or PC Cat 3527-7 $189 This tiny LCD screen is great for space critical situations. Cat 4658-7 $969 IDE RAID Controller This great capture card comes with a front access bay for easy access. Captures analogue and digital signals. Cat 23027-7 $399 Attach up to four IDE drives in RAID Cat 2886-7 $99 NEW! NEW! USB Serial Port External HD Case No serial port on your new laptop? This mini USB to serial adapter is the answer! Cat 2920-7 $54 This external case takes a 3.5" HD and connects via USB 2.0 Cat 6711-7 $129 Broadband Router/Firewall Share any broadband connection and protect your network with this router/firewall. Cat 10162-7 $129 SATA HD Rack This removable HD kit includes the tray and frame and is aluminium. Cat 6787-7 $139 NEW! FireWire 800 Card This PCI card supports both FireWire A and B with speeds up to 800Mbps Cat 2997-7 $129 Wireless PC Lock Automatically locks a PC when the user is more than 2m away from it. Cat 8545-7 $79 NEW! Optical AV Switch 802.11G PCI Card Switch between three inputs and one output. Has S-VHS, RCA, and Optical Audio. Cat 23023-7 $149 Suits both 32 and 64 bit PCI slots. A higher gain antenna can be attached. Cat 11443-7 $129 Optical to RCA Coaxial Converts two of the most common digital interfaces Toslink & RCA coaxial (S/PDIF). Cat 23006-7 $49 Wireless LAN Equipment! We’ve got the lot - antennas, cards, pigtails, converters, cables! MicroGram Computers Ph: (02) 4389 8444 FreeFax: 1800 625 777 Vamtest Pty Ltd trading as MicroGram Computers ABN 60 003 062 100, info<at>mgram.com.au 1/14 Bon Mace Close, Berkeley Vale NSW 2261 All prices subject to change without notice. For current pricing visit our website. Pictures are indicative only. See all these products & more on our website...www.mgram.com.au SHORE AD/MGRM1104 Dealer inquiries welcome MAILBAG Video formats: why bother? Jim Rowe is a braver man than I, in attempting to explain the reasons behind all those different video input configurations (August 2004), to even reasonably technically “fluent” electronics enthusiasts. I’ve given up trying to explain how and why you use the “16 x 9 scan” facility on TV sets with standard 4:3 tubes, in conjunction with the “16 x 9 output” facility on DVD players and digital set-top boxes! And nobody seems to have any idea what I’m talking about when I try to demonstrate the differences between Composite, Component and Y-C video. Even I have trouble telling the difference sometimes! There are a couple of small errors in his explanation of the use of luminance filtering in TV receivers. He states: “The problem here (in early TV sets) was that the low-pass filter ... had to have a cutoff frequency no higher than about 3.2MHz...” In fact, I have never encountered a luminance low-pass filter used in any colour TV receiver, nor is one necessary. With a proper “sync-coherent” colour subcarrier (ie, for PAL, one that is locked to precisely 283.75 times the line frequency plus half the field frequency), the visibility of the colour subcarrier on the screen is quite small. In most cases, a simple 4.43MHz tuned notch filter is all that is required, simply removing some of the dot pattern from large areas of colour. Although this leaves the chroma sidebands untouched, you really only notice these on colour bar signals and similar electronically generated patterns. The reality is, a well-designed standard PAL TV receiver will quite happily display luminance frequencies right out to 5MHz. The notch filter produces a small dropout at the colour subcarrier frequency but this is normally quite unnoticeable. This applies equally to the latest AV monsters, as to sets nearly 30 years old. (And yes, a surprising number of those old warriors are still going strong!) It is true 4  Silicon Chip that in recent years some el-cheapo TV sets have had some truly atrociously designed video output amplifiers, giving some pretty ordinary pictures, but this trend has now reversed with the proliferation of single-chip CRT drivers in even the cheapest models. Low-pass filters have to be used with VCRs on the other hand, because the colour recording and playback process involves some extremely rigorous processing to enable the recovered chroma signal to be displayed on an unmodified TV set. If any of the original chroma signals managed to get recorded along with the luminance, you would wind up with a mixture of processed and unprocessed chroma, which would produce unsightly patterning on the colour image. When VCRs were first introduced, it’s true there was simply no practical means of doing this, other than using simple low-pass filtering. Even low-end broadcast formats such as High Band U-Matic suffered from this limitation. In virtually all cases, the luminance bandwidth is flat to about 2.5MHz and then drops to zero by 3MHz. Using the “80 lines per megahertz” rule of thumb, 2.5MHz equates to about 200 lines. Although VCR playback signals have lost the subcarrier/sync coherency, the savagely reduced replay chroma bandwidth (typically ±300kHz) means that the TV set’s notch filter can effectively filter this out, so it all works happily enough. S-VHS (“Super VHS”) and the concept of Y-C signals actually dates back to a 1979 proposal by JVC for a “turnkey” portable video theatrette system that would allow currentrelease movies to be shown in remote districts. This proposal sank without a trace and S-VHS was then reinvented as a “Vi-Fi” consumer format that never really went anywhere and was finally massaged into a reasonably successful professional and low-end broadcast format! Because there is never any time when the luminance and chroma signals are mixed together during the playback process, it’s perfectly OK for the luminance signal to have residues of the original colour subcarrier in it, which means that you can record and play back a virtually full 5MHz luminance bandwidth from off-air signals. (Of course you get even better results if the luminance is recorded directly inside the camera without ever “seeing” the chroma signal, which was the basis of S-VHS camcorders). When DVD players came along, some manufacturers started to take advantage of the “S-Video” (Y-C) inputs available on some high-end TV receivers. Technically this was a mere detail: the analog luminance and chroma signals are generated separately in the MPEG decoder chips; all they had to do was divert some of these signals to the Y-C connector as well as combining them to produce a composite video output. Y-C inputs are capable of quite good results; the problem is that they were only really designed to handle the 300kHz chrominance bandwidth of VHS signals. Although a DVD player could easily provide chroma signals with a wider bandwidth, certain peculiarities of the NTSC system limit any such improvement to only 500kHz (at least without major changes to the decoder circuitry). Component video inputs on the other hand will deliver the full theoretical 1.5MHz chrominance bandwidth of NTSC signals, and in the present climate of international set design, this is the real reason TV set (and chip) manufacturers have gone for this system, even though S-Video is considerably simpler and cheaper to implement, on both ends. Otherwise S-Video would have been all there ever was! siliconchip.com.au Also, there seems to be a bit of confusion about the “Zone Plate” test signals shown in the article on the Video Enhancer and Y-C Separator. In theory, there should be no difference between the Y-C and Component input images. The reason we see a difference has more to do with the economics of DVD player design than the signal systems themselves! This is understandable if you appreciate what actually goes on in the MPEG decoder/PAL encoder chips. In an old-fashioned (20th century) analog chroma encoder, the colour difference signals are fed to a pair of analog balanced modulators to generate the two suppressed-carrier AM signals. These are then combined with the luminance signal to give composite video. In a modern DVD player, the entire modulated colour subcarrier is synthesised directly, by some very fancy software. This may not sound all that awesome, until you realize that the PAL 4.43361875MHz (and NTSC 3.579545MHz) colour subcarrier frequencies have no direct numerical relationship to the 27MHz master clock frequency most commonly used! How do they do it? Well, consider an ordinary 4.43MHz unmodulated sinewave being fed to an 8-bit analog-to-digital converter, clocked at 27MHz. What you would get is a 27MHz stream of bytes which if then decoded by a DAC would reproduce the original carrier. There would be no immediately recognisable pattern to the numeric values of the string of bytes though, because the 27MHz clock would be continually sampling at different points on the waveform. However, there is a definite mathematical relationship involved and a fast enough computer can reproduce this pattern with a suitable mathematical algorithm. From there it is a relatively simple matter to digitally multiply the samples with the values of R-Y and B-Y coming from the MPEG decoder, add the colour burst and voila: a complete modulated PAL subcarrier, direct from the DAC! While this works very well, they have to cut a few corners, and so very few (if any) DVD players produce a true broadcast-quality sync-coherent colour subcarrier. Unfortunately this siliconchip.com.au means that their wide luminance bandwidth is more prone to generating “cross-colour” artefacts. However, they can cheat somewhat; it is possible to identify and filter out just those luminance components which are most likely to cause cross-colour and that is what most manufacturers do. I can assure you, if that zone plate was generated by pointing a TV camera at an actual printed chart, the colour artefacts would be much worse! The reason why the Y-C and Component input displays look different is that in virtually all cases the luminance fed to the “Y-C” output is merely the “doctored” (pre-filtered) “Composite” luminance sans chroma! Apparently, generating a separate unfiltered “Y” signal for the “Y-C” output is simply too hard. I suspect the reason they don’t simply use the Y from the YUV output is that most DVD players also allow you the option of RGB output from the same sockets and the potential for user stuff-ups is simply too large! Keith Walters, via email. Atmel’s AVR, from JED in Australia JED has designed a range of single board computers and modules as a way of using the AVR without SMT board design The AVR570 module (above) is a way of using an ATmega128 CPU on a user base board without having to lay out the intricate, surface-mounted surrounds of the CPU, and then having to manufacture your board on an SMT robot line. Instead you simply layout a square for four 0.1” spaced socket strips and plug in our pre-tested module. The module has the crystal, resetter, AVR-ISP programming header (and an optional JTAG ICE pad), as well as programming signal switching. For a little extra, we load a DS1305 RTC, crystal and Li battery underneath, which uses SPI and port G. See JED’s www site for a datasheet. AVR573 Single Board Computer Caution on CFL driver power to TV With regard to the CFL Driver in the September 2004 issue, if it is to be used to power a TV, first understand that the power switch on the TV is designed for use on AC where any tendency to contact arcing is quenched during the zero crossings. These switches arc notoriously when switching more than about 100V DC, even on a 2-pole switch. Some TVs use a small power transformer to power the remote control receiver and CPU. This type of receiver MUST NOT be used on DC. It would seem to be a sensible idea to increase the value of the 6.8kΩ resistor to about 7.3kΩ by putting a 470Ω resistor in series with the original component. This should reduce the maximum voltage from the converter to around 335V while the unit is supplying standby power only or if the 12V line rises to say 14.5V as it could do while the battery is being charged in a vehicle. The reason for doing this is because most switch-mode power supplies work at about this value when operating from a nominal 240VAC mains This board uses the AVR570 module and adds 20 An./Dig. inputs, 12 FET outs, LCD/ Kbd, 2xRS232, 1xRS485, 1-Wire, power reg. etc. See www.jedmicro.com.au/avr.htm $330 PC-PROM Programmer This programmer plugs into a PC printer port and reads, writes and edits any 28 or 32-pin PROM. Comes with plug-pack, cable and software. Also available is a multi-PROM UV eraser with timer, and a 32/32 PLCC converter. JED Microprocessors Pty Ltd 173 Boronia Rd, Boronia, Victoria, 3155 Ph. 03 9762 3588, Fax 03 9762 5499 www.jedmicro.com.au November 2004  5 Mailbag: continued supply; higher voltages can cause premature power supply failure. The degausser can be converted to operate from DC by charging a 150nF 500V capacitor from the 335V supply through a 330Ω resistor and discharging it through the degaussing coil manually with a robust pushbutton switch. The resistor can be left connected permanently. When the coil is shunted across the capacitor, the circuit will oscillate in a decaying fashion for a short period and in so doing the flux reversals will demagnetise the CRT. The values are those I have used in the past with great success on professional portable monitors converted for battery operation. I have no idea if the values will work for the set mentioned in your article, however I see no reason why one could not experiment. Note if a new TV is modified or even if the back is removed, one is liable to void the warranty. Also fitting a manual degausser with a pushbutton switch and then using the set on the 240VAC mains would render the safety certification for operation null and void so BEWARE. Victor G Barker, VK2BTV, via email. Slander on CFLs unjustified Your editorial that CFLs aren’t economic, in the August 2004 issue, deserves a response. Until early this year I was on the body corporate of a large multi-story block of home units with 11 stair-wells that relied on artificial lighting. The cleaner, who was responsible for changing light globes, came to me asking whether it would be a good idea to fit CFLs instead of incandescent globes. We tried it. He had previously been having to replace all the bulbs at an average of every six weeks. None of the CFLs had failed at the point at which equal cost was reached; ie, purchase price plus cost of power used for both was equal. Only one CFL had failed within 48 weeks of being fitted, indicating that they met and exceeded the 8000-hour life their manufacturers claimed. In 6  Silicon Chip the end, it worked out that by using CFLs the body corporate was saving $600 per year just on the basis of globe costs and power, plus the cleaner’s time savings. I have used CFLs virtually since they came on the market and have had only one obvious premature failure. You really ought to be asking why you had the problems you did rather then slandering a good product. Secondly, I must comment on your answer in “Ask Silicon Chip” to D. K., of Innisfail, who asked whether the Smart Mixture Display would work with a diesel engine. If you were trying to be funny you should be more obvious, otherwise readers might conclude you give answers when you have no idea what you are talking about. Yes, the device will work with a diesel engine if it has an oxygen sensor but of course they don’t, for reasons that are obvious to anyone who knows the basic principles that diesel engines run on. Detecting a lean mixture on a diesel would be pointless. They run lean by design. That’s how they work. Gordon Drennan, Burton, SA. Comment: sorry Gordon, but the answer concerning the diesel motor was fair dinkum and oxygen sensors can be fitted. Properly adjusted, diesels are supposed to run lean. Many don’t. Voltage warnings supported I fully support your September 2004 editorial regarding the voltage warnings added to the projects in SILICON CHIP. Having some 45 plus years experience in electronics, I have seen (and been guilty of myself) too many accidents ending in smoke and tears. It is not only the beginner but the experienced technician and engineer that have the accidents that can put life and limb at risk. I spent the early part of this year working in an electrical safety testing lab which, excuse the pun, brought me down to earth with a thud! Me, with all the years of experience, had the basics brought home to me in no uncertain terms. Most of my time at the lab was spent testing mains voltage CFLs where the voltages could be in excess of 2500kV peak. Some voltage waveform measurements were carried out with respect to mains earth using an isolation transformer on the CRO and when measurements between output terminals were required, two isolation transformers were used, one on the CRO and one for the CFL. All this with a high-voltage probe to boot! As you correctly stated in your Publisher’s Letter, the main concern is the accidental transposition of neutral for active, which could render the earthy side of the CRO BNC connector live, with disastrous results. So big and bold warnings please. If I skipped them before, after my six months in the testing lab, I will read them now. Michael Abrams, Capalaba, Qld. Novices will make mistakes The letter by Otto S. Hoolhorst concerning unnecessary voltage warnings, in the September 2004 issue, has me a bit steamed up. To me, he appears to have no regard for safety, possibly his own but obviously not for novices. The old saying that “there are two things in life that are guaranteed, death and taxes” should have a third one added: “Novices will make mistakes”. Lots of times. That’s how we all learn. Most of us are lucky and no real harm is done. I have 30 odd years in the electronics game, both military and civilian and even now I screw up sometimes. I screw up through complacency, a novice because of lack of experience. We are only talking about a cautionary note but they are critical. A novice must be made doubly aware that incorrect actions can lead to disaster, especially with higher voltages. It’s no big deal if you let the smoke out of some component, it’s easily replaceable. But if you fry yourself in the process, maybe Otto is invulnerable but I’m sure not! Yes, that project may not really be one suitable for a novice but no doubt they will attempt to build it, if it fits a need. Therefore it’s best to err on the side of caution and safety. The thing Leo may have been too polite to mention in his “Publishers Letter siliconchip.com.au is the legal aspect. Would Otto like to be in Leo’s shoes if he has to explain to a prosecuting attorney why there was no warning that the project was potentially dangerous? Would Otto like to pay the fine/serve the time if someone died because they were not warned of potential hazards. I think not! Yet these days, a Publisher can be held accountable if an article they approved for printing is found to be a contributing factor in someone’s injury/death. Sorry Otto, those cautionary notes are there for a good reason. If they bother you that much, then too bad. Ralph Teichel, via email. Separating SMPS transformer core halves I read Keith Farmer’s letter on the subject of separating SMPS transformer core halves with much interest (Mailbag, July 2004). I have rebuilt several computer power supplies and as Mr Farmer found, not all transformers come apart after soaking in paint stripper. I found that after the paint stripper treatment, dunking the transformer in boiling water released the glue holding the core halves together. I would be reluctant to put an SMPS transformer core in a microwave oven in case the microwave energy caused high enough flux densities in the ferrite to produce an irreversible change in the magnetic characteristics. However, if Mr Farmer’s treatment worked and the power supply subsequently operated without a problem, well and good. Keith Gooley, Edinburgh, SA. Off switch is the best energy saver Your recent articles on energy conservation and compact fluorescent lighting are timely and welcome. With regard to the former, I found during an energy audit that standby loads were using 1.5kWh per day. As such, I have been promoting the “off switch” as the cheapest energy saver available for some years now. Additional benefits include lower fire risk in the home and longer appliance life. I have always been a little suspicious of the actual saving achieved siliconchip.com.au by using compact fluorescent lights. Apart from the high cost and short lifespan issues, I believe they may not be as efficient as the label indicates. At a demonstration I attended at the Central Queensland University in Rockhampton, it was shown that the power consumption of a 15W CFL was actually 35-40VA in some cases. I concur with your view on using fluorescent tube lights where possible. I find that low wattage incandescent globes, 25W & 40W, used in suitable locations for short periods are far more economical in the long term. Your advice to return CFL lights that fail prematurely is the only way we can expect product improvement. Perhaps LED lighting will be a suitable replacement in the future. Brian Bartlett, Rockhampton, Qld. CFL build quality is the key I have to agree that many CFLs die early. I have even had them fry the instant they were turned on for the first time but as one of the letters in your latest issue also mentioned, certain brands are much better than others. I have not had a Philips unit fail before around 6000 hours and have generally been very happy with them. The ones I have owned have certainly saved me a lot of money over the years. Another good brand is Osram, although they seem to be making their lamps in two places now; the cheap version comes from China while the better version still comes from Europe. You can buy the cheap ones in a pack of two for $5.99 in Coles supermarkets at the moment. And they are a nice warm white. I’m not sure how long they will run – will know that in a year or two I expect! Back when the Osram lamps were called Wotan (I believe you can still get them under that brand), they were made in Germany and were just about unkillable. I know of two people here who have Wotan lamps dating back over 10 years that are still running (one home has several lamps that age and they are all working fine). How many hours these lamps have on them is anyone’s guess, but it would be well over 10,000. Anyway, I pulled apart one of my Want really bright LEDs? We have the best value, brightest LEDs available in Australia! Check these out: Luxeon 1 and 5 watt LEDs All colours available, with or without attached optics, as low as $10 each Lumileds Superflux LEDs These are 7.6mm square and can be driven at up to 50mA continuously. •Red and amber: $2 each •Blue, green and cyan: $3 each Asian Superflux LEDs Same size and current as the Lumileds units, almost the same light output, but a fraction of the price. •Red and amber: Just 50 cents each! •Blue, green, aqua and white: $1 each. Go to www.ata.org.au and check out our webshop or call us on (03)9388 9311. Wotan lamps after I got tired of waiting it to die after three years. It had much better rated components than any Asian made unit I have seen. For instance, 550V-rated transistors compared to 400V in the cheap lamps, and a 450V filter cap compared to 350V to 400V (there is not much margin on a 350V capacitor on a 250VAC supply!). At the time I pulled it apart it had already paid for itself, despite costing $30 at the time, but had I not killed it during the disassembly then it would have saved me a lot more. So the problem is one of specification more than anything but build quality also comes into it. I had one lamp that was dead when bought, so I opened it up and found two of the tube leads touching each other. Separating them fixed it, and it is still going strong two years later. So my advice is to buy the better quality units, because like most things, you get what you pay for. Lance Turner, Templestowe Lower, Vic. SC November 2004  7 Want to go broadband anywhere . . . without waiting for ADSL or Cable connection? Look Mum: No Wires! A ustralians are amongst the world’s largest users of the Internet. These days, if you have a computer, the chances are you have an Internet connection. And chances are also that it is dial-up, sharing the phone line with your existing voice phone service. With the price of broadband ever falling, huge numbers of people have taken the plunge and signed up for one of the countless offerings available from an almost equally countless number of suppliers. 8  Silicon Chip If you have ADSL broadband, well done. As we have found, it’s not always as easy as the suppliers make it out to be. If you could get over the hurdle of ADSL availability (eg, signing up for anything on the Telstra network meant living within just a couple of kilometres of the telephone exchange) you then had to wait for Telstra to let you know that first of all your line By Ross Tester was capable of handling ADSL (and apparently there are many that aren’t, mainly due to cost-cutting installations in earlier, less-digitally-enlightened times). Then, some time (possibly weeks) later, you were informed that you had been connected to ADSL and you could plug in your broadband modem, sign up with an ISP and away you’d go. Hopefully. Many consumers have been caught out with “bargain” broadband connections, finding that the usage limits (and in some cases both upload and siliconchip.com.au downloads count) are unrealistically low. While 300 or 400MB sounds a lot for a dial-up user, it doesn’t take long to gobble that up – and then some. Most people find that when they connect the always-on broadband, usage increases dramatically (why look up a phone book when you can find the info on the net?) and the usage limits are very quickly exceeded. And that’s when some of the broadband ISPs really start earning bulk income: many ISPs charge downright exorbitant rates once you exceed your monthly limit. But that part of broadband is really another story (solutions for which we hope to look at in more detail in a future issue). Cable broadband has of course been an alternative – if (a) you could get it (and there are still vast areas which have not been “cabled”) and (b) if you could afford it. Cable broadband has, at least until recently, been significantly more expensive than ADSL. An aside: a mate of mine is an Optus cable broadband customer because ADSL isn’t available at his place. He pays about seventy dollars a month for the privilege. Not long ago, Optus magnanimously told him they were upping his limit from the current plan’s three gigabytes a month to ten. He very seldom uses any more than one gigabyte. Would they lower the monthly rate and keep him at three? Last time I saw him he was still whistling Dixie. OK, so what if you could bypass the whole ADSL/cable rigmarole and have a broadband connection literally within minutes? One that is at least competitive with Telstra/Optus offerings? And perhaps more importantly, one that doesn’t charge you extra for your excess usage? The Unwired system: in front is the Unwired “rabbit” modem, plugging into the ethernet connection on the laptop (USB versions are also available). It really is as simple as plugging in and turning on . . . providing you have wireless access. Enter Unwired If you live in Sydney, you could hardly have missed the ads for Unwired on commercial radio (OK, maybe you listen to the ABC . . .). Unwired is a one of the large number of service providers offering broadband Internet connection. But Unwired is different. As its name suggests, Unwired doesn’t rely on Telstra (or Optus cable, or any other copper) to connect you. It is totally wireless – all done via a network of 3.4GHz radio towers spread throughout Sydney, which (at the moment) cover about 90% of the population. siliconchip.com.au Unwired’s coverage of the Sydney area is pretty good, considering the topography. They cannot say how long the yellow bits will take to come on line. November 2004  9 and other key regions in Australia for service expansion. They aren’t saying when but we’d be surprised if it’s not sooner rather than later, because Unwired has a very heavy investment in the spectrum space needed to provide the service. How much investment? A cool $100 million+ is the figure being talked about. So how does it work? Run, rabbit, run: the back end of the Unwired modem shows just two sockets, one for power and one for (in this case) PC Ethernet connection. Right now there are 69 of these towers; shortly that will extend to 73 and cover closer to 95%. Note that said population, not area. There is a big difference! Of course, due to Sydney’s topography there will always be some pockets not reached but according to Unwired, these will be relatively few and far between. It’s not the same coverage as mobile phones but it’s not too dissimilar. And while it is only available in Sydney right now, Unwired has targeted Brisbane, Melbourne, Adelaide, Perth We’ve published several articles in SILICON CHIP about WiFi – digital wireless “networking” using (mainly) the 802.11b or 802.11g standards on 2.4GHz. Well, Unwired is not WiFi – although it is similar in some respects. For a start, it is significantly higher in frequency – around 3.4GHz. Wifi, via a wireless network card inside your desktop PC, or a PC card or USB stick attached to your laptop, links to a local access point, itself “hard wired” to ADSL or cable in the normal way. Hence your connection to the ’net is based on standard copper wire technology until the last little “hop” via wireless. It also depends on that access point being and staying connected. Often (usually?) you have to pay for the privilege of using it and in some cases, it can be as expensive as using an internet café! Unwired users have an entirely different type of connection – it uses a special wireless modem (often called a “rabbit” – and if you look at the photos, you’ll see why!) to connect to one of their strategically-placed towers. It doesn’t even have to be line-of-sight but it does have to be within range. They talk about a range of around 10km Setup is as simple as following the step-by-step screens that appear when you run the setup CD which comes with the modem. 10  Silicon Chip The front end of the Unwired Modem showing the fold-up rabbit ear antenna plus the three indicator LEDs and power switch. (which, at 3.4GHz, is not too shabby!). Unwired is based on a proprietary (and patented) system called “MultiCarrier Beamforming Technology” (MCSB) from Navini Networks in the USA. It’s also known as Nomadic Wireless Broadband Access, bringing wireless not just to an antenna or dish on the roof (as some other systems do) but right to the user’s computer (or at least to the modem close by). To connect to Unwired, you simply plug in the modem. That’s either via a USB port or an Ethernet port, Naturally, you have to sign up to one of the Unwired plans before you can start surfing – but you can do this on line as part of the setup procedure. It’s delightfully simple to do. siliconchip.com.au depending on the type of modem purchased. The modem cost, by the way, is about $189, either on-line (direct from Unwired or via several agents) or retail from technology chain Harvey Norman. If you’re in a reception area, after a few seconds one of three coloured LEDs on the unit glows steady. You then sign up for a plan using your credit card, and you’re on line. Total elapsed time? You’d hardly have enough time to get the egg out of the fridge, let alone boil it . . . Speed Once connection is established (and we’ll look at that in a moment), there appears to be little difference between apparent speeds loading and browsing sites I was familiar with using Unwired or using ADSL/cable. Given the fact that I was using a computer which would have little if any cached sites, I was pleasantly surprised by the speed and smoothness of the wireless system. The three plans on offer run at 256/64Kbps, 512/128Kbps and 1024/256Kbps (download/upload speeds – like ADSL, Unwired is not synchronous). Unwired does not run at a constant speed; it varies according to usage of the system at any given time in much the same way as cable broadband varies: more users, lower speed. For the two weeks or so I played with Unwired, I cannot say speed ever dropped to “too low” levels, although I have read many reports of people complaining of sluggishness at certain times of the day (especially early evening). Also, I experienced none of the dropouts which have been reported in other media, although given the minimal signal strength in my area I would not have been surprised to find dropouts a problem. There have also been reports of massive variations in signal strength on different floors of the same building – one report, surprisingly, said that on the fourth floor there was no signal while on the ground floor there was. Not wireless? Believe it or not, there has been comment in the popular press (and on newsgroups) that Unwired really isn’t a wireless system because you have to connect the modem to your PC and also to a power outlet. Sheesh!! What do they want? Taking the second point first, they’re wrong, because the Unwired modem contains an internal rechargeable battery which will give you up to an hour’s connection away from a power source – as our lead photo (and front cover) shows! The other objection really doesn’t warrant a comment, except that it points up a very good reason for not having non-technical journalists And here’s the proof: the SILICON CHIP website on screen less than three minutes from the time we turned the computer on. Speeds on the service we had were commensurate with our mid-range ADSL service at the SILICON CHIP office. siliconchip.com.au What about iBurst? While we have been concentrating on Unwired, other wireless contenders have recently launched on the Australian market, or are in the process of doing so even as this issue goes to press. The most prominent of these is iBurst, backed by the large ISP Ozemail. Their Personal Broadband service was launched in late September (although it would appear that Ozemail have renamed theirs Metrowide Wireless). Unfortunately, we couldn’t look at iBurst as we have Unwired, because as yet it doesn’t have much coverage of Sydney’s Northern Beaches at all! iBurst uses a different system (Arraycom’s IntelliCell technology) to achieve a somewhat similar result. Like Unwired, it will offer broadband coverage over a wide area of Sydney (though not yet as wide as Unwired) but is already launching into interstate markets. Most of the northern Gold Coast is already on line (sorry, wrong choice of words – not on line, on wireless!) and iBurst was promising to have Brisbane, Melbourne and Canberra up and running within a matter of weeks. In fact, iBurst will offer two versions of its wireless service – one is a mobile system in the true sense of the word, capable of giving a seamless connection to a notebook computer in a car travelling at up to 50km/h. Tests we have seen haven’t been quite so good as the marketing hype suggests but still relatively good, nevertheless. Prices are relatively steep at $99/month for a 1MB per second/1GB limit service and $199 per month for a 1MB per second unlimited service. Still, if mobility is important to you, you’re probably prepared to pay the price. The second service is similar to the ADSL/cable alternative offered by Unwired – ie, portable, not mobile. Prices are more reasonable (though slightly higher than Unwired), starting at $49.95 a month for a 256KB service and $99 for a 1GB service. Ordering is via the web (www. ozemail.com.au) with modem delivery within 24 hours. Ozemail promise to have your account activated by the time you receive your modem. November 2004  11 nificant degree when the wavelength approaches the raindrop size. 3.4GHz signals have a wavelength of about 0.09 metres or 9cm, a tad larger than even Noah-sized rain. For all intents and purposes, you can use the figure of 10GHz as the minimum affected frequency (for the same reason, Ku-band [11-13GHz] satellite signals can be affected by rain while C-band [4-5GHz] are relatively immune). How well does it work? After you’ve purchased the wireless modem (about $189, which is significantly more than an ADSL/cable modem), the plans are not dissimilar to the plans offered by wired broadband ISPs. The minimum plan is $34.95 per month. talking about matters technical in the non-technical press! And now I have that off my chest . . . What affects Wireless strength? The location of the antenna can often make the difference between no signal at all and wall-to-wall signal... or anywhere in between. Because in the case of Unwired the antenna is an integral part of the modem, that means placing the modem in the most advantageous position. Filing cabinets, steel-reinforced concrete walls, aluminium-backed wall or ceiling insulation . . . even someone walking between your modem and the wireless tower (wherever that might be) can cause degradation or even total loss of signal. That’s why you might need to experiment somewhat for best signal level. It’s quite common to read reports of rock-solid signal on one side of a building and low or no signal on the other. Low signal levels mean that data speeds are reduced or sometimes data disappears and the link drops out. The USB or Ethernet (crossover) cables supplied with the modem are only a couple of metres in length. But you might need to place the modem (say) on the other side of the room for best signal strength. The Ethernet modem would be the best option here because you can buy significantly longer cables (many 12  Silicon Chip metres long) which will have little apparent effect (if any at all) on your system speed. Naturally, your system will need an Ethernet card for this to be practical – either on-board, as most late-model desktops and laptops are, or an add-in Ethernet card (fortunately now VERY cheap!). The USB option, on the other hand, does limit you to a fairly short distance. You can buy USB extension cables but your maximum is just a couple of metres more. Otherwise you would have to start looking at amplifiers – our advice is to stick with the Ethernet version. Is Wireless affected by rain? Mmm – good question. There’s a lot of discussion about this point, with some saying it is (a little) and some saying it isn’t at all. Because wireless signal strength DOES vary significantly due to any number of factors, we believe that rain might often be the innocent victim – eg, signal strength’s down a bit today. Yep, it’s raining. Therefore it must be the rain causing it. (Corollary: the bank robber was described as having blue eyes and blonde hair. There’s a blue-eyed blonde. He must be a bank robber . . .). The truth is (at least according to many satellite websites that we’ve looked at) that rain normally only starts affecting radio signal to any sig- Here’s where we came across the first stumbling block. Unwired’s marketing people suggested we try the system “both at home and in the office” because they were selling Unwired as suitable for both home use and small office use. OK, first thing I did was had a look at the Unwired coverage map on their website. Like many ADSL/cable websites you can type in your street name and suburb and you’ll get a map showing availability (www.unwired. com.au/availability/current.php). I did – type my street name in, that is. Aaaaaagh!!!! Not in the service area. Strike one. (Of course I tried – just one street away I managed excellent reception. One lousy street!). I have seen several comments about being able to use Unwired well outside their “official” service area. But not in my case. So I thought I’d try the SILICON CHIP office and typed in the address. Aaaaagh!!!! Strike two. In fact, the whole of the Mona Vale area, one of the major retail, business and industrial centres of the Northern Beaches, is not covered. That was a surprise. When I raised this anomaly with the people from Unwired, they informed me that there was a site available for a tower which would solve the problem for both areas. But thus far they had been stymied by some misguided tree-hugging souls who maintained that those electromagnetic thingies would make them glow in the dark or something. (So they used their mobile phones to call all their friends to the protest . . .) No strike three! What to do? Fortunately, my “home away from home”, Narrabeen Beach Surf Lifesaving Club, was in an area with coverage (it is in a pink area on the Unwired website map). siliconchip.com.au So – down to the club, plugged the modem into the Ethernet socket on the club’s PC, turned it on and . . . no signal. You can tell whether you have signal by the three LEDs on the front of the unit. Green means a very strong signal, orange a strong signal and red a good signal. Flashing red means no signal. As advised in the setup, I moved the modem slightly closer to a window and, joy of joys, the LED stopped flashing – “good” signal. Elsewhere in, and outside, the club (away from the foil-covered roof insulation), the signal was green – excellent. The setup via the supplied CD was, thankfully, a doddle and I was on the net literally three minutes from when I turned the PC on – including entering the password and user names which Unwired had thoughtfully provided. Mr or Mrs Average Citizen would get their password and user names when they first log on and purchase their plan. Unwired in use Quite simply, I found using Unwired broadband very similar in performance to the two other broadband services I regularly use: ADSL here at SILICON CHIP and cable at home. Regrettably, I wasn’t in a position to do any actual speed tests (I was about to but the trial period ran out!) but purely by observation, I would have to say I was pretty happy with the way Unwired broadband behaved. That feeling was further backed up when one of my colleagues here at SILICON CHIP took the Unwired modem home for a few days. He’s in the north-western suburbs of Sydney and reported an instant “green” signal (excellent level) when he plugged in Unwired and no problems whatsoever with surfing the ’net. Unlike me, he is close enough to the exchange to theoretically get ADSL but suffers from the Telstra “pair gain” bogey so it’s back to the “incompatible infrastructure” excuse. Though Foxtel cable is available in his street, given his success with Unwired, he’s pretty firmly convinced which way he is going to go. Is Unwired safe? A few moments ago, I made somewhat flippant comment about electromagnetic radiation. But is that a concern with the Unwired system? siliconchip.com.au Given the fact that Unwired is “up there” on 3.4GHz (much higher than mobile phones, WiFi or even microwave ovens!) AND the fact that you have a device emitting e-m radiation very close to where you are working, perhaps it is something to be wary of. Where I was being sarcastic was in objections to electromagnetic radiation from Unwired towers: sure, transmitted energy levels will be higher but the inverse square law tells me that the radiation at ground level would be diminished to virtual background levels. Having said that, I would be wary about having an Unwired modem in close proximity to where I’m sleeping (and let’s face it – a lot of kids would have their PC, ergo their Unwired modem, on a desk next to their bed). In fact, I’d want to keep the distance between it and me as far as practical. Even Unwired themselves have a warning with the modem that it should not be used within 20cm of a person. It’s probably more of a “protect your butt” clause than anything else but it’s something to keep in mind. Do you really need a phone line any more? Many of Sydney’s (and, obviously, Australia’s) young, mobile population live in rented accommodation which may or may not include a phone line. Even if it does, there’s the cost and hassle of having the phone connected, rent to pay, not to mention (in the majority of cases) the inconvenience of a different phone number when you move. That’s why so many people have given away the fixed phone line, instead relying on their mobiles to stay in touch. If and when they move, their phone number goes with them. And there’s no re-connection fee, line rental, bond, whatever. Now even that is set to change as we enter the Wireless Broadband era. Last month we featured Voice Over IP, (VoIP), explaining how it could dramatically lower your phone bills – especially if you were on broadband. Unwired is broadband. You are already paying for the connection (without time constraints) so why not use Unwired in conjunction with a Netphone or headset on your PC to make ALL your “phone” calls. Hey, this could even replace mobile phones! Admittedly, calls are costed by time but if you’re not one to sit on the phone for hours, it is a completely viable option. As we pointed out last month, quick local calls can even cost less than what you currently pay. Long distance is where VoIP really starts to shine. So there it is: a new service which we believe will revolutionize not just the way we surf the net but the way we use our telecommunications systems and infrastructure. For more information, visit www. unwired.com.au SC COMING NEXT MONTH Satellite TV reception – the downside of Unwired Those who remember the first (VHF) television bandplan implemented in Australia will remember that it was a total debacle, with channels 3, 4 and 5 bang-smack in the middle of the international FM broadcast station allocation. “It’s OK,” they said at the time. “Australia doesn’t have any FM radio stations. . .” Not then, we didn’t. It’s taken the best part of fifty years to unscramble those particular eggs. Believe it or not, the Government has done it again, with wireless broadband. Our satellite TV writer, Garry Cratt, will tell how the powers-that-be have managed to auction off chunks of the international C-band Satellite TV spectrum for data communications. The net result is that people who have gone to considerable expense to set up their own C-band receiving systems (dishes, LNBs, receivers and so on) are now complaining long and loud about wireless broadband. The spread of frequencies is again right on top of many of their favourite satellite signals and in this case, Goliath wipes out David every time. “Too bad” say the authorities. “You’re not supposed to be watching overseas satellite television programs anyway. . .” In some cases, the problems can be cured, or at least eased, as Garry explains next month. November 2004  13 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: dicksmith.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: dicksmith.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: dicksmith.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: dicksmith.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: dicksmith.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: dicksmith.com.au The GM Silverado/Sierra hybrid is a full-sized pickup truck. Unlike the Toyota Crown, it doesn’t use an electric motor as a traction motor or for mechanically powering accessories when the engine is not running. Instead, it uses a conventional 5.3-litre V8 and 4-speed automatic transmission with a 14kW, 3-phase induction AC starter/ generator sandwiched between the transmission and the engine. Energy storage is by a 36V lead-acid battery. [GM] The New Era in Car Electrical Systems The first cars using the new 42V standard are now being released. So why the move from 12V and what are the implications for the design of higher voltage car electrical systems? By JULIAN EDGAR B ACK IN OUR JULY 2000 issue, we briefly looked at the way in which vehicle electrical systems are changing. The use of high-output alternators and 42V electrical systems were being mooted as technical solutions to the ever-increasing electrical power demands in cars. What’s happened since? Well, in a few words – a lot! Toyota in Japan currently sells a car with a 42V electrical system, while GM in the US is this year releasing a 42V pickup truck – and some organisations are already using pre-delivery vehicles. New technical standards are being developed to cover everything from 42V battery terminal and fuse 20  Silicon Chip design to the colour-coding of 42V wiring. Automotive component suppliers have developed 42V alternators, starter motors, circuit breakers and other components. Some are predicting that by 2010 as many as half of all vehicles will use 42V electrical systems. In 20 years, the forecasts suggest that all cars will use this voltage. Even more interesting is the relationship developing between “mild” petrol/electric hybrids and 42V electrical systems. Throw in the increasing availability of mains power in cars (yes, that’s right – in the USA you can now have a factory-fitted mains power socket in your car!) and the whole area of car electrical systems is undergoing a change of a magnitude never seen before. Power-hungry cars The trends in automotive technology can be summarised as: • Better fuel economy • Reduced exhaust emissions • Improved safety • Better comfort and convenienc Each of these has implications for the load placed on car electrical systems. For example, improvements in fuel economy can be gained by applying systems such as automatic engine stop/start capabilities, electricallyassisted acceleration from a standstill, electric engine cooling pumps and fans, and electric power steering and air-conditioning. Also being thoroughly investigated is the electromechanical operation of engine valves. While it could bring about significant increases in engine power and efficiency, this approach looks likely to be electrically power hungry, with estimates of up to 2.4kW peak loads on a six-cylinder engine. siliconchip.com.au Table 1 • • • • • Daimler Chrysler Renault/Nissan General Motors Peugeot/Citroen Ford • • • • • Fiat BMW Toyota VW/Audi Honda Car manufacturers in North America, Europe and Japan currently developing 42V cars Reductions in emissions can come from electrically heated catalytic converters (some cars already have these), while dynamic safety can be improved by the use of active electric power steering, active suspension and high-powered electric de-icing of glass. Finally, increasing comfort and convenience can lead to the use of electrically heated and cooled seats, electrically heated steering wheels, high-end sound systems, in-car computers, navigation systems and the provision of mains-power sockets. Even without including electrical propulsion, components supplier Delphi expects the growth in electrical loads in cars to be 5% per year over the next 20 years. If electric propulsion is included, that estimate rises to 8% per year. Fig.1 shows the past and estimated future increases in car power demands. The consumer acceptance of the latest model Toyota Prius – this year Toyota expects to sell 50,000 in the USA alone – has given car manufacturers the confidence to start thinking seriously about incorporating electricassist into otherwise conventional designs. These so-called “mild hybrids” use electric assistance only in certain conditions. For example, in a mild hybrid, the petrol engine is turned off whenever the vehicle is stationary. The electric motor then helps the car accelerate as the petrol engine re-starts. The gains in fuel economy are not as great as in high-voltage full hybrids but the manufacturing and development costs are much lower. This acceptance of mild hybrids makes the rate of growth in electrical power demand likely to be close to Delphi’s 8% per year estimate. 42V systems Prior to 1955, vehicles used 6V elecsiliconchip.com.au Fig.1: past and estimated future increases in car power demands (note the logarithmic vertical axis). The massive increase in electrical power loads is seeing a move to 42V systems. [Delphi] ACCESSORIES BELT STARTER (INITIAL START) PULLEY MAGNETIC CLUTCH ENGINE GEAR MOTOR/GENERATOR (MG) INVERTER 36V BATTERY DC/DC CONVERTER DRIVE WHEELS 12V BATTERY ECU CONTROL UNIT Fig.2: the mild hybrid Toyota Crown is the first car in the world to feature the new 42V standard. It uses a 3kW 3-phase AC synchronous motor/ generator in conjunction with a 147kW petrol engine. The transmission is a conventional 5-speed automatic. The motor/generator, which is larger than a conventional starter motor but not as large as the traction motor used in a full hybrid, charges a 20Ah 36V battery via a water-cooled inverter. [Toyota] trical systems. However, recognition in the US that higher ignition energy would be required for the high compression V8s then being introduced prompted the adoption of a higher voltage system. In addition, the introduction of higher power headlights, radios and higher-powered starter motors were all showing the limitations of the 6V system. 12V systems – using 13.8V regulation – were then introduced, with most manufacturers achieving the transition within two years. November 2004  21 STARTER MOTOR/ GENERATOR CONTROL UNIT 12V BATTERY OIL PUMP 36V BATTERY Fig.3: in the Toyota Crown, the 12V battery is charged via a DC/DC converter and the 36V battery from the generator inverter. Both batteries are mounted over the rear axle of the car in the forward section of the boot. [Toyota] 36V VALVE REGULATED LEAD ACID BATTERY INVERTER, ECU DC-DC CONVERTER MG AT OIL PUMP ELECTROMAGNETIC CLUTCH Fig.4: the use of an electromagnetic clutch allows the Toyota’s motor/generator (MG) to drive the accessory belt even when the engine is off. By engaging the clutch, the motor generator can start the engine and even help propel the car. [Toyota] The increasing power demand of current cars has now caused a similar situation to develop – a higher voltage is needed. However, the situation isn’t quite the same – there are far more devices of vastly greater sophistication working on the current 12V standard than there were working on 22  Silicon Chip 6V in 1955. The new standard is termed a 42V system. That is, battery voltage is 36V with the bus regulated at 42V. Basing the standard on the 42V running-car voltage, rather than the 36V lead-acid battery voltage, was done to cater for future developments that might displace lead-acid batteries and traditional charging systems. One benefit of increasing the voltage to 42V is a reduction in wiring gauges. A current mid-size car has a wiring loom that weighs 35kg or more and contains 2km of wire, 1000 cut leads and 300 connectors. With the potential for loads of many kilowatts (the catalytic converter heating in the BMW 750iL requires a short-term power of 17kW!), the current flow required at 13.8V becomes very high indeed. As a result, conductor sizes are large, adding cost and weight. Increasing the voltage reduces the current flow and so smaller conductors can be used. In addition to reducing conductor size, adopting a 42V standard allows the development of powerful combined starter/generators, more compact and powerful electric motors, and other actuators that are smaller, have a lower mass and improved performance. Table 3 shows some of the benefits of adopting 42V systems. Another advantage of the higher voltage is in the field of semiconductors. The cost of semiconductor switches, which are expected to be used very widely in cars, depends on the current and voltage ratings of the device. The current-handling capability is related to the semiconductor’s area, while the voltage rating is tied to the device’s thickness and doping profile. A reduction in required current capability results in a smaller chip area, decreasing costs. For example, an electric powersteering controller may need to handle a power of 600W. At 14V with an assumed electronic efficiency of 85%, the switch is required to handle 50A. However, at 42V the required current handling drops to less than 17A, reducing the cost of the powerdependent components by 60%. But why just 42V? If reductions in conductor and electric motor size are the criteria, why not use 500V, say, as does the current model Toyota Prius? There was widespread consensus that the new voltage standard should be sufficiently low to ensure the personal safety of those that come in contact with it. During the development of the new standard, the Society of Automotive Engineers performed an in-depth study of the research that had been carried out on human tolerance to electrical shocks. The society concluded that protection against direct contact siliconchip.com.au Toyota Crown Running Modes The petrol engine switches off whenever the car is stationary. On restart, the electric motor/generator drives the car and starts the engine. In normal driving the petrol engine propels the vehicle. If battery charge is low, the electric motor/generator is used to charge the battery. During braking or any other time that the fuel supply to the engine is cut, the electric motor/generator regeneratively brakes and so charges the battery. When the vehicle is stopped, the engine is turned off and the electric motor/generator powers the accessories such as the air-conditioning compressor. [Toyota] was not required if the voltage did not exceed 65V DC, including ripple. Subsequently, the German standards body VDE reduced this to 60V. The specification of 42V systems suggests that a maximum bus voltage of 55V is permitted during dynamic overvoltage conditions. Table 1 shows car manufacturers in North America, Europe and Japan currently developing 42V cars, while Table 2 lists the automotive component suppliers currently developing 42V components. The first 42V cars The first two cars featuring 42V technology are mild hybrids that run dual 12/42V electrical systems. The Toyota Crown mild hybrid has been produced in small numbers in Japan siliconchip.com.au since 2001 and initial deliveries of the General Motors Silverado/Sierra hybrid twins are occurring now, with full sales to begin later this year. (1). The Toyota Crown Mild Hybrid: the Crown uses what Toyota dubs a “Toyota Hybrid System – Mild”, or THS-M. Fig.2 shows its layout. A belt-driven motor/generator comprising a 3kW 3-phase AC synchronous motor is used in conjunction with a 147kW 3-litre in-line 6-cylinder petrol engine. The transmission is a conventional 5-speed automatic. The motor/generator, which is larger than a conventional starter motor but not as large as the traction motor used in a full hybrid, charges a 20Ah 36V battery via a water-cooled inverter. The motor/generator is used to: • restart the stopped engine (initial starting is by a conventional 12V starter motor). • help drive the vehicle when moving away from a standstill. • generate all electrical power. • provide regenerative braking on deceleration. • drive engine auxiliaries when the engine is stopped. The 12V battery is charged via a DC/DC converter. Both batteries are mounted over the rear axle of the car in the forward section of the boot (Fig.3). The motor/generator, which is located where a conventional belt-driven alternator normally would be, is able to drive the accessories with the petrol engine stopped because in this mode a magnetic clutch is used to decouple the accessory belt drive system from the engine. November 2004  23 Just some of the parts developed for the mild hybrid Toyota Crown (clockwise from top left): the engine; 36V battery; inverter & electronic control unit; and electric motor/generator. Fig.4 shows an overview of the engine bay. In stop/start urban conditions, fuel consumption is improved by about 15%. (2). GM Silverado/Sierra hybrid the GM Silverado/Sierra hybrid is a full-sized pick-up truck. Unlike the Toyota Crown, the GM mild hybrid does not use the electric motor as a traction motor or for mechanically powering accessories when the engine is not running. It uses a conventional 5.3-litre V8 and 4-speed automatic transmission – the design criteria required that an existing GM engine be used and that the transmission had only minor modifications for its new hybrid vehicle role. Overall driveline length also needed to remain the same as non-hybrid versions. In order that these criteria could be met, the starter/generator (GM call it simply the ‘electric machine’ - EM) is inserted between the engine and the transmission, with the torque converter being reduced in diameter to create the space. To overcome problems of excessive heat resulting from a smaller torque converter, the transmission control strategy is revised to allow Table 2 • • • • • • • • • Bosch Motoral SPS Aisin Motoral AIEG Continental Teves Siemens VDO Delco Remy America Infineon Delphi Table 1 •• Daimler • Yazaki Chrysler •• Renault/Nissan • Denso •• General Motors • Valeo •• Peugeot/Citroen JCI (Johnson Controls)• •• Ford • Visteon Fiat BMW Toyota VW/Audi Honda • Lear Car manufacturers in North America, Europe and Japan currently developing • Varta 42V cars • Magneti Marelli Some of the automotive component suppliers currently developing 42V components. Delphi, for example, state that they can now provide a complete 42V generation, conversion, storage, distribution and usage system. 24  Silicon Chip earlier-lock-up of the torque converter clutch. The EM is then used to reduce poor driveability resulting from this early lock-up. The EM is a 14kW, 3-phase induction motor. The rotor is bolted to the engine’s crankshaft and surrounds the torque converter. This approach allows the crankshaft’s bearings to support the rotor. The stator is located around the rotor and is supported by an assembly positioned by existing dowels projecting from the rear of the engine block. It is clamped between the transmission and the engine. The stator is watercooled via a thermostat-controlled feed from the engine coolant system. Changes made to the transmission included the use of a unique bellhousing and flex-plate and an alteration to the hydraulic valve body that allows the transmission to drive the engine (and so the EM) on over-run in second and third gears. In addition, a small electric pump is used to provide hydraulic pressure within the transmission until the transmission pump is rotating quickly enough to provide normal working pressures. The GM mild hybrid uses these strategies to reduce fuel consumption: • deceleration fuel cut-off much more frequently used, with the EM smoothing the resulting torque fluctuations. • automatic engine stop during stationary and very low speed vehicle operations. • lower speed torque converter lockup clutch engagement. • regenerative braking. A 42V electro-hydraulic power steering pump replaces the traditional engine-driven unit, while air conditioning requirements with the engine stopped are met by “careful management of refrigerant capacity already in the system prior to the stop”. The traditional starter motor is deleted. 42V challenges The change in such a universal and long-standing car standard as 12V has some major challenges – technical and financial. Taking the latter first, why should customers feel any urge to pay more for a car that has a 42V electrical system? General Motors puts it like this: “A 42V system is only an enabler. It is not something that consumers will be willing to pay for directly – so it absolutely must deliver the capabilisiliconchip.com.au MAINS OUTLETS General Motors see the inclusion of 110VAC power sockets in their mild hybrid pick-up truck as a major selling point of hybrid technology. The circuits are protected by ground fault detection and up to 14kW is available. ties and features that customers desire and value.” The company suggests examples of such customer-desirable features are mains-power outlets, new entertainment systems, electrically heated windscreens, fast heating and cooling systems and “by-wire” chassis and engine controls. They also suggest the thinner wiring looms and smaller components will provide space for more features likely to appeal to the consumer. The fuel economy achieved by 42V combined starter/generator systems will also have immediate consumer appeal. It’s for customer justification reasons that GM has highlighted the availability of mains power (there are four outlets!) in its promotion of the Silverado/Sierra hybrid. General Motors delivered its first hybrid pick-up truck on May 3, 2004. The mild hybrid uses a combined electric motor/generator and boasts 10-12% improved fuel economy. The car is only the second to use the new 42V standard. [GM] 12V/42V possibilities What about cars where a 42V electrical system is introduced in conventional engine form? As with the two hybrid cars that we’ve looked at, it’s very likely that cars will continue to have both 42V and 12V systems for some time to come. In fact, it is suggested that incandescent lighting will stay at 12V because of bulb durability issues associated with the automotive use of higher voltages. Three 12V/42V architectures are likely to be used: • Single voltage generation and single voltage energy storage – a 42V alternator charges a 36V battery which services 36V loads, with a DC/DC converter used to charge a 12V battery siliconchip.com.au The GM mild hybrid control system incorporates an inverter to generate 110VAC mains power (four mains power outlets are provided on the truck), a DC/DC converter to operate the 12V loads and an inverter that operates the starter/generator. [GM] that services 12V loads; • Dual voltage generation and single voltage energy storage – a dual 14V/42V alternator charges two separate systems, one 12V and the other 36V; • Dual voltage generation and dual voltage energy storage – a dual 14V/42V alternator charges a dual 12/36V battery. In all cases the inclusion of 42V car systems poses challenges in controlNovember 2004  25 Table 3 Current Technology Benefits of 42V Architecture Electric power steering More power, improved fuel economy Electric brakes Redundant power supplies Power windows, power seats, power hatchback lifts Reduced size and mass of motors; more efficient operation Heated catalytic converter Lower emissions; quicker light-off time Heating, ventilation, air-conditioning blower motors and cooling fans Greater efficiency; smaller/lighter units; flexible packaging Mobile multimedia More power available for video, mobile phones, navigation systems, audio amplifiers, fax machines Water pumps Improved efficiency; longer service life Selected engine management system components (eg, exhaust gas recirculation valves, ignition systems, control actuators) Reduced size and mass; increased performance Fuel pumps Reduced size and mass Heated seats Faster heating, more efficient operation; increased power The benefits to current automotive electrical technology of adopting a 42V system. [Delphi] ling arcing and corrosion, especially in the presence of contaminants like salt water. (An example? – consider a boat trailer’s electrical system that can be under water quite frequently!) Another “real-world” problem is the use of jumper leads. To prevent people with 42V cars attempting to jump-start 12V vehicles, 42V vehicles will have non-accessible batteries and use a dedicated jump-starting connection with a unique, fused connector. 42V jumper leads will be specific to the application and incorporate microprocessor control. One proposal sees the use of 42V jumper-leads occurring in the following manner: • Connect terminations to each car or car and boost pack. • Units activates (wakes up) and checks polarity – both LEDs flash. • LED flashes red if either or both batteries are reversed. • Low current circuit is activated and checks for conductivity. • If all is OK then green LED flashes. • Switch is pushed and internal relay is activated – green LED on. • Relay is opened if either battery is disconnected – green LED flashes. • If both batteries are below 36V or either battery is below 18V, relay will Super-Capacitors For 42V Systems Super-capacitors suitable for 42V automotive systems are being developed. These capacitors can be used to meet peak loads and then be recharged over a period from an existing battery or at a fast rate through regenerative braking. A 10kJ, 42V super-capacitor has sufficient energy to operate the combined starter/generator of the 5.7-litre V8 GM Silverado/Sierra hybrid for two consecutive engine starts (the engine starts in 0.3–0.5 seconds). Compared with a lead-acid battery, a combined super-capacitor-battery prolongs battery service life with its ability to handle high recharge/discharge events typical of a mild hybrid car. However, at this stage super-capacitor costs remain high when compared with traditional battery technology. 26  Silicon Chip Suppliers have already developed a complete range of 42V automotive components. Here are two 42V compatible bimetallic circuit breakers, available in 5 - 30 amp ratings. [First Technology] not activate – red LED on. Fuses also need redesigning. Testing was carried out of normal 12V blade-type fuses on 42V and it was discovered that when subjected to overload, terminals could melt away (probably through arcing) and the plastic fuse housing was subjected to intense heat, resulting in carbonisation and melting. New 42V fuses use polyamide housings and feature a slightly different shape to 12V fuses, preventing 12V/42V fuse inter-changeability. Circuit breakers suitable for 42V operation are already available. Wiring standards also need to be upgraded. The current proposal is that all 42V wiring is coloured amber. Because of the potential problems of arcing, all 42V terminal connections will need to be correctly seated and locked. More sealed connectors will be used. Note that not all wiring will be reduced in conductor size – in many cases those wires that are 0.35mm2 will remain that size even when working on 42V, as this is the minimum size for mechanical durability. Conclusion While it was initially thought that the first 42V cars would be luxury cars with very high electrical power loads, mild hybrids have beaten them to the punch. In addition, a report that Daimler Chrysler has put 42V system development on hold appears to be a temporary setback for that company. However, over the next few years a wide range of cars will appear with 12V/42V systems and as they become common, it won’t be long before dediSC cated 42V cars appear. siliconchip.com.au 0 $2 T S LL JU R A IS FO TH OF WG1 NEW 200W WIND GENERATOR These are serious 3 phase 200W wind generators with blades spanning 2.2M. They are designed to start operating in low air speeds (around 11kph) while being robust enough to withstand strong gales. They are rated at 200W <at> 25kph with a max. of 250W. Each generator is supplied with a 3 Phase rectifier and a Meter box. One of the meters measures the battery voltage, the other measures the charging current. These generators output 3 phase (sine) and our optional new charger kit will enable you to charge banks of batteries. For more information and instructions see our website. We have suitable 5.5M mast at no extra cost, but would require an engineering certificate. A disclaimer form needs to be completed, signed, and mailed back to us before the order can be processed. Please call/email for more information. 12V / 200W WIND GENERATOR: (WG1A) $699 24V / 200W WIND GENERATOR: (WG1B) $699 NEW Toshiba BATTERY PACKS 4 X 4 800 mAh Ni-MH cell battery packs. These cells are as long as a AA cell and as thick as a AAA cell. New in original packaging. (2D0060) 4 packs for $5 NEW SAFT BRAND 500mAh AA NICAD CELLS These French made high quality cells come with solder tags attached. (2D0061) 5 for $2 110-240VAC 50/60Hz to 24V <at> 1A POWER SUPPLIES This small 94 X 63 X 28 fully enclosed housing has 1.8M output cable with a four pin DIN style plug and a STD (NEW) DC MOTORS: common figure 8 mains 4 brush, 4 magnet, 16 pole. 11 tooth input socket, mains lead sprocket to suit a chain pitch around not supplied. New in 7mm. Double ball bearing for long original packaging. (KC24)Only $4 each life. Mounting bracket with 4 treaded NEW LARGE COLOUR LCD Hitachi LMG9200XUCC holes 6mm X 1mm (M6) 100mm Dia. These high resolution colour LCDs are brand new laptop x 80mm L (+ shaft) Shaft: 27mm x displays. There are not easy to connect to or to drive. 8mm (8mm x 1.25mm. (M8) 2kg. 200W 24VDC, 11.0A, 2750 RPM, $30 (SC200) A Internet search showed lots of info. (LGM) $15 each 300W 24VDC, 16.4A, 2650 RPM, $36 (SC300) NEW BRIGHT 5mW 635nm VISIBLE LASER MODULE This module emits an orange/red beam which is more SPEED CONTROLLERS visible and brighter than the 650-670nm modules. Speed controller modules for the 24V motors we stock. Consists of a visible laser diode, diode housing, APC They come with a diagram. These units require a 4K7 or (automatic power control circuit) driver, and collimation 5K pot & a 2k7 resistor (not supplied) to replace the lens all factory assembled in one small module. Requires original throttle. ~4.5V to operate and consumes approx. 50mA. Overall CONTROLLER (SPC150) UP TO 150W/24V dimensions of unit are 8mm dia. by 13mm.$11 (LM1) See throttles on our website MOTORS: $14 OXG1- cross generating optic $0.55 CONTROLLER (SPC350) OLG1 - line generating optic $0.55 UP TO 350W/24V NEW 6VDC LUXEON LED DRIVER KIT MOTORS: $24 This kit is designed to drive 1-3W from 4-6V, PB12 (NEW) 12V / 12AH GELL CELL BATTERY: usable down to 3V! Measuring 150mm L X 94mm H X 95mm W and weigh Shown actual size approx. 4100g. If you are looking for a charger check out $5.90 . (K216) our (SCC12) and (SCC24) mains powered chargers. (NEW) 12V / 24V CHARGERS: PICAXE-08M MICROCONTROLLER CHIP These chargers charge at a fast rate reducing the current This is the new version that has in-built tunes. with the rise in charge but should not be left indefinitely. $4.70 Check our web site for more PICAXE chips. Charging figures from a quick test were 2.5A charge <at> SUPER PRICES ON NEW UHF MODULES 11V, 2A charge <at> 12.4V and 0.4A charge <at> 14.9V. Cheap home automation with these new miniature UHF 12VDC CHARGER: modules.Band width limited to 240VAC - 12VDC <at> 1.2kbs. 2300mA: (SCC12) $17 (TX434) $9 (RX434LC)$9 24VDC CHARGER: 240VAC - 24VDC <at> POWERFUL DC MOTORS / GENERATORS: The 200W motors are the same as used in our scooters. 1300mA: (SCC24) $17 They are very powerful for there size, 24V use, but produce lots of torque at 12V. They start rotating at only COMING SOON 0.5VDC. These motors make great generators . When 30mW+ GREEN driven at a low speed with a cordless drill they produced 6V open circuit, 5V <at> 5A & 4V <at> 8A; Very reasonable LASER HEADS. Requires a constant freight costs to most Australian capitals. DANGER!!! current source only, (NEW) 100W DC MOTOR: For experienced typical 500mA<at>1.8V 100W output as used in our laser users only small scooter. 24VDC. Rated speed: 2300 RPM Rated current: 6.0A Measures: 67mm X 97mm LOW INTRODUCTORY PRICE $350!!! (+ shaft) Shaft: 8mm "D" shaped end Also coming. complete laser light show kit using these with cir-clip groove. Weight: Approx. 1.1kg. $22 (SC100) laser heads. 2.2M (NEW) CHARGER / DISCHARGER + 40 Ni-MH CELLS New in original box with instructions. This unit was designed to charge and discharge NI-CD & NI-MH mobile phone batteries of 4.8V, 6.0V and 7.2V. Operates from 12-24V DC input. Features include processor control & multi stage charge indicator. Includes cigarette lighter lead, 12V / 1A DC plugpack (worth around $30) & instructions for modifications for higher voltages. All of this plus 10 packs of Toshiba 4 cell pack 1.2V <at> 800mAh NI-MH Batteries. Each cell measures 10mm x 50mm (same length as AA & same diameter as AAA batteries). Pack size: 12.5mm x 64mm x 48mm. (ZA0100PK) $20 REDUCED PELTIER DEVICE PRICES!!! Dim: 40 x 40 x 4mm. GP1 4.0A Device / D T 65° / Qmax 42W, $10 GP2 6.0A Device / D T 65° / Qmax 60W: $13 GP3 8.0A Device / D T 65° / Qmax 75W: $16 NEW ELECTRIC BIKE Size: 1130 x 390 LY N O 00 $3 x 1000mm Brake: hand brake, rear wheel drum brake. Battery capacity: 12AH, 24V. Battery charger: 240V Motor power: 200W. Charging period: 4-5 hours. Speed: 20km/h. Range: 15km. Wheels: inflatable. Frame: painted steel. Weight: 21kg. Maximum load: 100kg. Forget waiting for trains and busses that don't come, the regulations on the NSW RTA website indicate that they can be ridden under the same rules as a bicycle. Come complete with batteries, lights and charger. $300 (SC3) More info on these and more items on our website. ELECTRIC BIKES/SCOOTERS SC1 (NEW) 100W ELECTRIC SCOOTER: This portable light weight IAL scooter folds up for easy EC carrying and storage. Ideal SP EW N CE Christmas gift for the kids. I Features variable speed PR 94 $ control and hand lever style brake. Material: aluminium & steel painted with lacquer. Brake and throttle can be swapped from side to side. Telescopic handlebars to suit most riders. It comes complete with mains charger and batteries. Unlike a lot of others these have Australian electrical approvals including C-TICK. Speed: 12km/h Motor: 100W Battery: 2x 12V, 4.5A Range: 10-15km G.W: 10kg N.W: 8kg Size: 740 x 130 (deck) x 930mm. www.oatleyelectronics.com Suppliers of kits and surplus electronics to hobbyists, experimenters, industry & professionals. Orders: Ph ( 02 ) 9584 3563, Fax 9584 3561, sales<at>oatleyelectronics.com, PO Box 89 Oatley NSW 2223 OR www.oatleye.com major credit cards accepted, Post & Pack typically $7 Prices subject to change without notice ACN 068 740 081 ABN18068 740 081 SC_OCT_04 Tired of having to switch the power to your PC’s peripherals on and off manually, as well as switching the PC itself? Here’s a simple way to make life easier by having the PC control the power to its peripherals automatically via one of the USB cables. There’s only a handful of components involved and they can be built right inside a low-cost multi-way power distribution board. USB By JIM ROWE UP A USB-controlled Power Switch M ost of the first generation of personal computers had an ‘IEC’-type 240V outlet on the back of the box, which provided power switched by the PC’s own power switch. This allowed you to control the power to the computer’s monitor, printer and other peripherals simply by plugging in a power distribution board to this outlet and plugging the peripheral power cords into the distribution board outlets. The power switch on the front or side of the PC then controlled everything, which was very neat and convenient. Unfortunately this handy switched power outlet disappeared from later models, presumably because it became harder to implement when PC manufacturers changed over to softwarecontrolled power supplies. So, with most newer PCs, if you wanted to control everything with a single switch, you’ve been forced to use a power distribution board with its own master power switch. There is a way to get true singleswitch operation, though, if you’re using a recent model PC with at least one USB port (and that means just about any PC made in the last few years or so). This is to control the power fed to the peripherals using an electronic switch triggered by low-voltage DC from the PC itself, via its USB port. The electronic switch then turns the peripherals on when the PC is turned on, and turns them off when it’s turned off. Here’s the completed project, mounted (in this case) inside a Kambrook KPB6 Powerboard. One outlet is sacrificed in this version to accommodate the USB-UP PC board and a label is fitted over the unused outlet. 28  Silicon Chip siliconchip.com.au PLEASE NOTE: This project involves opening and modifying a mains powerboard. Do not attempt this project unless you are experienced in mains wiring and construction. Contact with the mains can cause severe injury or death. Never work on a power board with the plug in an outlet, let alone turned on. ALSO: While the original powerboard is rated at 10A, 240V (2400W) the modifications made limit the total loading to around 700-750W, or 3A. This limit should be more than adequate for the intended application: switching computer peripherals. Forgive the mess of cables: normally these would of course be behind or under the desk, out of sight. But then we wouldn’t be able to show you the USB-UP powering the monitor, amplified speakers, external IDE/ USB disk, printer, even a phone charger . . . The electronic switch needs to be optically isolated, so there’s no risk of 240VAC getting back into the low voltage circuitry of the computer via the USB port. But a high-voltage optocoupler neatly solves that problem. In this article we’ll show you how to build a USB-controlled electronic power switch right inside a low-cost power distribution board, for maximum safety and convenience. How it works When a PC is powered up, +5V DC appears on pin 1 of each of its USB port sockets. We simply tap off a few milliamps from this convenient source of 5V DC, to trigger a 240V Triac via an optocoupler. The Triac therefore switches power to your peripherals whenever the PC is powered up. The circuit is shown in Fig.1. A pair of standard USB sockets, CON1 and CON2, allow the circuit to be connected in series (ie, daisy-chained) with any normal USB peripheral cable. All of the USB connections go ‘straight through’, so the added circuitry is essentially transparent as far as USB communication is concerned. The connections to the USB port are to pin 1, the +5V line, and pin 4, the ground (0V) line. Across the two we connect the input LED of OPTO1, an MOC3021 opto-isolated Triac driver, with a 220W resistor in series to limit the current to 15mA – just sufficient to ensure reliable triggering. The optical isolation inside the MOC3021 is rated to withstand voltage ‘spikes’ of up to 7.5kV peak, which reduces the risk of flashover to a very low level. The 470W and 390W resistors and the 47nF ‘X2’ rated capacitor ensure that when OPTO1 is triggered on it in turn switches on the BT137F Triac, at very close to the zero crossings of every 240V AC power half-cycle. Finally, a series combination of a 10nF capacitor and a 39W resistor is connected directly across the Triac to form a ‘snubber’ circuit. This protects the Triac against spurious triggering caused by mains spikes or switching spikes produced by inductive loading of some of the peripheral device power supplies. Construction We have a designed a small PC board which fits into typical 6-way distribution boards like the Jaycar/Powertech MS4031 or the Kambrook KPB6. The Jaycar Powerboard has the advantage of having room inside the case for mounting without “surgery” and also contains spike and noise suppression; however it is more expensive than the Kambrook Powerboard. The only way to fit the PC board inside the Kambrook unit is to sacri- The alternative power board from Jaycar, the Powertech MS4031. It is more expensive than the Kambrook but does not need any “surgery” to fit the USB-UP PC board inside (so you retain all six outlets) and also has very worthwhile surge/spike protection built in. siliconchip.com.au November 2004  29 WARNING: WIRING & COMPONENTS IN THIS AREA ARE AT 240V MAINS POTENTIAL WHEN THE CIRCUIT IS OPERATING. CONTACT MAY BE LETHAL! 220Ω OPTO1 MOC3021 1 390Ω 2 47nF 275VAC X2 CLASS 4 MAINS ACTIVE IN TRIAC1 6 λ 470Ω 10nF 275VAC X2 CLASS A1 BT137F G 39Ω A2 MAINS ACTIVE OUT CON2 USB SKT TYPE A CON1 USB SKT TYPE B 1 Vbus 4 GND USB IN FROM PC 2 D– 2 3 D+ 3 1 4 USB OUT TO PERIPHERAL BT137F USB-up POWER SWITCH SC 2004 A2 A1 G Fig.1: the circuit diagram shows that the USB connectors are wired “straight through” so USB devices connected are unaffected. The circuit steals a few milliamps from the USB to turn on a fully isolated triac and thus the powerboard. fice one of the six outlets and mount the board in its place. We’ll explain how shortly. The PC board measures 48 x 43mm and is coded 10111041. The board has rounded cutouts in two adjacent corners, to allow them to be fitted between pillars inside typical distribution boards. Fitting the components to the PC board shouldn’t present any problems if you follow the overlay/wiring diagram carefully. Just make sure you fit the two USB sockets in the correct positions, as they are different in terms of their pin layout. Take care with OPTO1 and TRIAC1, to fit them the correct way around. The Triac body is held down against the PC board using a 6mm M3 machine screw and nut. Before mounting the PC board in a typical 6-way distribution board, you have to open up the board by removing the ‘tamper proof’ screws which fasten the upper and lower halves together. These screws can usually be removed fairly easily using a matching hex-shank bit from one of the multi-bit sets available from many electronics suppliers and bargain stores. Or you can make your own “tamper proof screw” screwdriver by filing a small (2mm or so deep) notch in the centre of a spare flat-bladed screwdriver of suitable size. Once you have the board opened, there will be a different procedure, depending on whether you are installing the PC board into the Jaycar/ Powertech MS4031 or the Kambrook KPB6. Let’s talk about the Jaycar distribution board first. Jaycar MS4031 Powerboard You can see the general arrangement from the internal photos which were taken inside a Jaycar MS4031 board. There is just enough open area in the end of these units to fit the PC board assembly. Making the connections is as follows: the short brown wire connecting the ‘Active’ bus bar of the six outlet sockets to the original RFI filter board (at the cord entry end of the case) is removed, and replaced with a 300mm length of similar brown 250VAC-rated wire running from the existing RFI filter board down to one of the mains MAINS ACTIVE OUT MAINS ACTIVE IN 10111041 10nF 14011101 275V AC 470Ω 47nF 275VAC USB IN CON1 3 2 4 1 39Ω 390Ω OPTO1 MOC 3021 220Ω TRIAC1 BT137F CON2 4 1 3 2 USB OUT Fig 2 (left): the PC board overlay, with the PC board pattern itself shown at right. In the centre is the completed PC board for comparison. 30  Silicon Chip siliconchip.com.au Parts List – USB-UP 1 PC board, code 10111041, 48 x 43mm 1 6-way power distribution board (see text) 1 Type B USB socket, PC-mounting (CON1) 1 Type A USB socket, PC-mounting (CON2) 3 25mm x M3 Nylon machine screws (Kambrook) or 9mm 6G self-tappers (Jaycar) 1 6mm M3 metal screw 4 M3 nuts & lockwashers Semiconductors 1 MOC3021 opto-isolated Triac driver 1 BT137F 600V/8A isolated-tab Triac STEP-BY-STEP: Modifying the Kambrook powerboard The Jaycar powerboard is similar but note the differences as explained in the text! After checking (twice!) that the powerboard is not plugged in to an outlet, remove the back and identify the active (brown) wire between the overload switch and the active bus (left pic). Cut this wire at both ends and remove it. Capacitors 1 47nF 275V ‘X2’ rated metallised polypropylene 1 10nF 275V ‘X2’ rated metallised polypropylene Resistors (0.25W 1%) 1 470W 1 390W 1 220W 1 39W connections on the new USB switch board. Then an additional 30mm length of the same wire is used to connect the second mains connection on the switch board to the adjacent ‘other end’ of the long brass strip forming the Active contacts of the outlet sockets. The board is mounted in the end of the case using three 9mm long 6G self-tapping screws, which mate with pillars already moulded into the inside of the upper part of the case.The only work required on this part of the case is to trim down a couple of these pillars to the same height as the shortest original one, so they form a stable support trio. This can be done quite easily using a sharp hobby knife. The Triac body is held down against the PC board using a 6mm M3 machine screw and nut. At the opposite end of the powerboard, cut the Active, Neutral and Earth bus bar straps immediately after the fifth outlet. Remove these, then cut away the plastic supports for the sixth outlet. Grind them down until they are nearly level with the case body. Cut away the appropriate slots for the USB sockets, using the drawing below as a guide. Fill in the empty outlet holes with silicone sealant. Drill the three 3mm holes in the bottom of the case to accept the three Nylon mounting screws. The completed project in the top of the Jaycar powerboard (immediate right) and the bottom of the Kambrook powerboard (far right). The Jaycar version is by far the easier to make. siliconchip.com.au November 2004  31 UPPER HALF ALL DIMENSIONS IN MILLIMETRES 11.5 10 2.5 12 18 24 14.0 JAYCAR POWERBOARD LOWER HALF SIDE VIEW UPPER HALF END VIEW ALL DIMENSIONS IN MILLIMETRES 11.5 12 18 24 10 14.0 KAMBROOK POWERBOARD REMOVE LIP ONLY LOWER HALF SIDE VIEW END VIEW These diagrams should assist you with the USB slot cutouts. At the top are the cutouts for the Jaycar powerboard with the Kambrook powerboard below. It will be necessary to make cutouts for the USB connectors in the lower half of the case. A slot is cut in the end of the case half to clear the Type A output socket, while a square hole is cut in the side for the Type B input socket. I found it fairly easy to cut the slot using jeweller’s files, but it was necessary to drill some holes in the side to ‘start off’ the rectangular hole. The idea is to work slowly and carefully, so you don’t make either cutout any larger than is necessary to clear the two sockets. That’s about it. After fitting the USB switch board into the case and making the two connections, you can reassemble the case again using either the original ‘tamper proof’ screws or some ordinary self-tappers. Kambrook 6-way powerboard The procedure in the Kambrook power board is different because there is no space at the end as in the Jaycar example. To make space, we cut the brass connecting strips between the fifth and sixth 3-pin sockets and discarded them, then removed all of the plastic contact supports for the 3-pin socket. The easiest way to do this is to carefully break out small pieces with a pair of pliers, then smooth the whole lot with a rotary grinder. To be sure, to be sure, we filled the now-vacant 3-pin socket holes with some silicone sealant to make sure nothing could be put into the holes. The other main difference between the Kambrook and Jaycar boards is that we found it much easier to mount the PC board in the base of the Kambrook unit (rather than the top as was used in the Jaycar board). The reason for this is that there is a continuous plastic barrier strip moulded into the base of the Kambrook unit which turned out to be 9mm high – the same height as the mounting spacers we used. So there was no need to cut away any of this barrier – the PC board sits on top of it, held in place by the three Nylon screws, nuts and 9mm spacers. The Nylon screws need 3mm holes. After you’ve drilled the three holes and removed any burrs, push the Nylon screws through from the outside, fit metal spacers, then the PC board. The same square cutouts need to be made to give access to the USB sockets; in the Kambrook power board matching cutouts are needed in the lip on the bottom section. In some ways, the cutouts are easier on the Kambrook case top. We simply cut down the required amount using a hacksaw blade (see diagrams for distances), then bent the waste back and forth with a pair of pliers until it snapped off. One piece snapped off nice and cleanly but Murphy’s law ensured that the other needed cleaning up with a fine file. Because the slots in the base are so shallow, the same fine file can be used to make them. Once the slots are cut and the screw-holes drilled, the board can be installed and wired up. A label is then fitted to the case to block off the slots for the now Here’s the Kambrook powerboard, completed but not yet screwed back together. 32  Silicon Chip siliconchip.com.au unused 3-pin socket. The original ‘tamper proof’ case assembly screws can be re-used again if you wish, or replaced with normal 6G selftapping screws. Using your USB power board Putting your USB power board to work is easy. All that you need to do is connect the USB ‘upstream’ socket (on the side) to one of the USB ports on your PC, using a standard USB connection cable. The power leads of your peripheral devices then plug into the distribution board’s outlets, so their power is controlled by it. Just bear in mind the Finally, the powerboard closed up again, immediately before we fitted the label over the now-unused sixth outlet. You can see the difference between the two types of USB socket in this photo. The label is shown below left, same size. USB-UP USB-Controlled Mains Switch 240 Volts, 700 Watts MAX SILICON CHIP 750W (3A) total loading. If you have USB leads from peripheral devices already plugged into all of the PC’s USB ports, that’s no problem. Simply remove one of them from a USB port socket, and plug the lead from the USB Power Switch into that socket. The lead from the peripheral can now be plugged into the output or ‘downstream’ socket on the Power Switch, so it’s reconnected to the same USB port. And Bob’s your uncle! Your peripherals will now be automatically turned on and off with the computer. SC THE AMATEUR SCIENTIST Two incredible CDs with over 1000 classic projects from the pages of Scientific American, covering every field of science... See the review in the October 2004 issue (read on line at www.siliconchip.com.au) SOL Arguably THE most AMAZING collection of scientific projects ever put together! This is version 2, Science Fair Edition from the pages of Scientific American. As well as specific project material, the CDs contain hints and tips by experienced amateur scientists, details on building science apparatus, a large database of chemicals and so much more. “A must for every science student, science teacher, science lab . . . or simply for those with an enquiring mind . . .” ONLY 49 $ 00 PLUS $7 Pack and Post 1st Shipment:OUTD SO Use the handy order form Exclusive in SILICON 2nd Shipment:OULTD on page 65 of this issue, or SOLD www.siliconchip.com.au call (02) 9979 5644 (bus hrs) Australia to: CHIP OUT 3rd Shipment: 4th Shipment Due This Month. Order now to avoid disappointment! siliconchip.com.au November 2004  33 Pt.1: By JOHN CLARKE A charger for deep-cycle 12V batteries If deep cycle batteries are not properly charged, they will never be able to deliver their full capacity and their life will be greatly reduced. You can’t use a generalpurpose 12V car battery charger. This 3-step charger is specially designed for deep cycle batteries and will charge at up to 16.6A. D EEP CYCLE BATTERIES are expensive and are designed for a long life. If properly charged and looked after, they should last 10 years or more. Their chemistry is quite different from that of car batteries and if you use a charger intended for car batteries, you will definitely not get their maximum capacity. 34  Silicon Chip Furthermore, if deep cycle batteries are consistently under-charged, they will have a short life. By compari­ son, car batteries are seldom charged above 70% of their capacity but they are designed for “shallow” discharge. If they are subjected to frequent deep discharge, they will have a very short life. Deep cycle battery manufacturers specify that their batteries should be charged up to a fixed value called the “cyclic voltage”. Once the battery is charged to this level, the voltage must be reduced to the “float” voltage and then it can be left permanently connected to the charger. Continuous charging at the cyclic voltage will damage the battery. The cyclic voltage is usually different for each type of lead acid battery. For example, standard lead acid batteries should be charged to 14.2V and floated at 13.4V, while Gel-Cell (Sealed Lead Acid) batteries should be charged to 14.1V and 13.3V respectively. These voltages are for a battery temperature of 20°C. At higher temperatures, the voltages must be reduced and the amount of compensation is also dependent on siliconchip.com.au battery chemistry. Typically, lead acid batteries require a temperature compensation of -20mV/°C while Gel-Cell batteries require -25mV/°C compensation. Clearly, a low-cost charger has no means for setting the required cyclic voltage and nor can it provide the float voltage setting or temperature compensation for these voltages. Our new charger provides a 3-step charge cycle comprising an initial bulk charge, an absorption phase and then a float charge. A separate equalisation charge mode is available after the absorption phase, if required. Equalisation is important for deep-cycle batteries and should be run three to four times a year. Our charger includes an LCD that shows charging mode and temperature plus battery voltage and charging current. The display can be set to show the battery amp-hour (Ah) setting, battery type and whether equalisation has been selected. Fig.1: this graph shows the battery voltage during charging. There are three steps to the charging cycle: an initial bulk charge, an absorption phase and then a float charge. An optional equalisation charge phase is also available for deep-cycle batteries. Battery capacity A charger must not supply too much charging current to the battery. The optimal charging current is related to the capacity of the battery and its internal chemistry. Our charger sets the initial charge to 25% of the battery’s amp-hour (Ah) capacity. For example, for a 40Ah battery, the initial charging current will be 10A. For higher capacity batteries, the charging current will be limited to 16.6A, the maximum that the charger can deliver. During the initial charging phase, the display shows BULK on the top line, while the second line shows the temperature, voltage and current. For example, the display might show 26 Deg C, 14.2V and 15.0A. The °C reading is measured by an external temperature probe, normally placed on the battery case. The voltage and current readings are the battery terminal voltage and the charging current, respectively. During bulk charge, battery voltage will gradually rise from an initial 12V (or whatever the initial no-load voltage is) towards the cyclic voltage. The battery voltage is continuously monitored and the charger detects when it reaches the cyclic voltage threshold. The cyclic voltage is the value selected for the particular battery type and is compensated with respect to temperature. siliconchip.com.au Fig.2: the battery current during charging. The charging current is maintained at 25% of Ah during the bulk charge and then tapers off during the absorption phase. It is then fixed at 5% of Ah during the (optional) equalisation process. When the battery reaches the float voltage, a small charging current maintains it at this level. When the battery reaches the cyclic voltage, the charger switches over to the absorption phase. This is shown as ABSORPTION on the display, while the second line continues to show temperature, voltage and current. During this phase, the cyclic voltage is maintained by adjusting the current. The initial stages of the absorption phase maintain the charging current at a similar value to that during the bulk charge. However, as time goes on, the current will be reduced so as to maintain the constant cyclic voltage across the battery. This reduction in current is an indication of battery charge so that when the current falls to around 2% of charge, the battery can be considered to be around 90% charged. At this point, the charger switches to float or equalisation. Equalisation sets the current to 5% of the battery Ah and charges for an- other three hours. Equalisation breaks down sulphation on the plates and thus extends the life of the battery. It also makes sure that each cell within the battery is fully charged, to equalise the cells. During this phase, the display shows EQUALISATION and also shows the temperature, voltage and current. The battery voltage is likely to rise above 16V during this phase and this will cause the display to show --.-V. The maximum battery voltage is restricted to the setting of the over-voltage limit. Equalisation should be run only a few times per year since it will reduce battery capacity if used too often. Finally, the charger switches to float and the display shows FLOAT. This takes place at a lower voltage to that of the absorption phase and is temperature compensated. The battery is then left connected to the charger to further November 2004  35 Main Features • Suitable for 12V lead acid bat• • • • • • • • • • • teries LCD shows charging phase and settings Temperature, voltage and current metering 3-step charging Optional equalisation phase Battery temperature compensation 16.6A charge capacity Initial trickle charge when battery voltage is low 4 preset battery chemistry settings 2 adjustable specific battery settings (can be set for 6V batteries) Correction for voltage drop across battery leads Wide battery capacity range (4-250Ah) in 18 steps increase the charge by a few percent and also to prevent self-discharge. The entire charging process is shown in the accompanying graphs (Fig.1 & Fig.2). Fig.1 shows the battery voltage during charging while Fig.2 shows the battery current. As shown in Fig.2, the charging current is maintained at 25% of Ah during the bulk charge and then tapers off during the absorption phase. It is then fixed at 5% of Ah during the (optional) equalisation process. The current subsequently normally drops to near zero immediately after absorption (or equalisation) and then the battery drops to its float voltage level. This may take some considerable time. When the battery reaches the float voltage, a small charging current maintains it at this level. Note that Gel-Cell (SLA) and AGM batteries can accept a higher charge rate than the 25% of Ah delivered by the charger. To achieve this, the Ah setting on the charger can be increased to a value that is about 1.6 times the actual Ah of the battery. For example, for a 40Ah battery you can use the 60Ah setting. This will increase the current to about 40% of Ah during bulk charge. In addition, the point at which the charger switches from the absorption phase to 36  Silicon Chip float charge will increase by the same proportion – ie, from 2% to about 3% – but should be of no consequence. The equalisation current will also be increased by a factor of 1.6. As a result, if equalisation is selected, the Ah reading should be set to the correct value. Note that there is no point in increasing the Ah setting for batteries that are above 40Ah in capacity because the charger can only deliver a maximum of 16.6A, as noted above. Safeguards There are various safeguards incorporated into the charger to prevent possible damage to the battery. First, at the beginning of bulk charge, the battery voltage is checked to see if it is above 10.5V. If it is below 10.5V, the charging current is limited to 2% of the selected Ah value, until it rises to a level where it is safe to apply 25% of Ah current. Note that there is a facility to charge a 6V battery and the equivalent safety threshold is then 5.2V. Second, the duration of the absorption phase is not just set by a timer, as in some commercial designs. A timer on its own would not prevent the absorption phase re-running for the duration again should the battery be recharged before it has been discharged. Excessive recharging at the cyclic voltage will cause grid corrosion in the battery, leading to reduced battery life. So as well as timeout, our charger incorporates a low current detection set at 2% of the battery Ah, at which point float charge is initiated. This feature means that if the battery is recharged before it is discharged, the bulk charge and absorption phase will be short and float charge will happen almost immediately. In addition, equalisation will not occur unless it is selected manually. As a further precaution, if the battery temperature rises above 40°C, equalisation will not occur after the absorption phase, even if it is selected. Similarly, if the battery temperature rises above 40°C during equalisation, the charger will switch over to float mode. Finally, if the battery voltage rises above the over-voltage setting, the charger will switch off and show BATTERY ? on the display. User settings When the charger is switched on, the display prompts the user to select the battery settings: Ah, battery type and whether equalisation is required. Selecting Ah (battery capacity) sets the correct charge rate. The display shows BATTERY AMP HOUR on the first line and <200Ah>, for example, on the second line. At this stage, the charger is not delivering current and the desired battery Ah is set using the “<” and “>” switches. The second battery setting is the battery type and should also be selected or checked by pressing the set switch again. The display now shows BATTERY TYPE on the first line and <LEAD ACID>, for example, on the second line. The battery type can be selected using the “<” and “>” switches to change the settings. For example, the Gel-Cell, AGM, Calcium/ Lead, Specific #1 or Specific #2 batteries could also be selected. The third battery setting is for equalisation. Pressing the set switch will have the display show EQUALISATION on the first line and <OFF> on the second line. Pressing either the “<” or “>” switch will change this to <ON>. Equalisation will then occur after the absorption phase. Charging will not begin until the start switch is pressed. If the battery is not connected, the charger will not place any voltage on the battery clips. This prevents any sparking at the terminals when connecting the battery while the charger is switched on. Note that after charging has started, the switches become locked so that the settings cannot be changed. This feature will prevent any tampering with the settings during charging. The set switch will only operate if it is pressed before 25% of Ah current is reached. If the switch is pressed during this time, charging will cease. Charging can then be restarted with the start switch. A jumper can be removed from within the charger for automatic starting when power is applied. Automatic starting is a useful feature in the event that the charger is only ever used on one particular battery. Should the battery settings require changing, the set switch can be pressed as soon as power is applied to bring up the battery settings on the display. Again, this will prevent charging until the start switch is pressed. Another jumper must be removed from within the charger in order make changes to the Specific #1 and Specific siliconchip.com.au Fig.3: the block diagram of the charger. The power transformer feeds 18VAC to bridge rectifier BR1 and the resulting unfiltered DC is fed via a power controller circuit to the battery via fuse F2. The power controller is controlled by a PIC microcontroller (IC5), in conjunction with IC3, IC4 and IC1b. #2 battery parameters. This prevents tampering with the parameters. Should the battery clips be removed from the battery terminals during bulk charging, the charger will either go to the absorption phase or charging will stop and the display will show BATTERY ?. The charger will then need to be switched off and on again using the mains switch to initiate the original charging phase. Fail-safe protection has been incorporated for battery temperature compensation. If the temperature probe is not connected or has gone open circuit, then the battery temperature is assumed to be 40°C. This reduces the cyclic and float voltages to prevent damage to the battery, even in high ambient temperatures. The display also shows two dashes (--) in place of the temperature reading, to indicate a fault in the temperature reading. Finally, the circuit is protected against reverse battery connection by a 20A fuse. Charger protection A 3A slow-blow fuse protects against failures in the mains transformer and the charger circuit, while the abovementioned 20A fuse protects against output short circuits. Fan cooling for the heatsink is provided, with siliconchip.com.au a thermostat cutting in and switching the fan on when the temperature rises above 50°C. If this cooling system fails, a second thermal cutout set at 70°C shuts down the charger. Over-voltage and over-current limiting are also provided, via the circuit itself and via software control. The software is arranged to switch off the charger if the output goes above 16V during normal charging (except during equalisation) or the charging current rises above 20A. An over-current fault will cause the display to show <OFF>. The over-voltage and over-current thresholds are set using trimpots, to 17V and 18A respectively. Voltage sensing When charging a battery, it can be difficult to obtain an accurate reading of the voltage right at the battery terminals. This is because there will be a voltage drop along the leads due to the current flow. Some battery chargers overcome this problem with separate voltage sensing leads but unless the leads are moulded together, they can be a nuisance and become tangled. Reserve Capacity Some battery manufacturers use the term reserve capacity (RC) to specify battery capacity and this is distinct from the more readily understood amp-hour (Ah) rating of the battery. The two specifications are not directly interchangeable. The Ah capacity refers to the current that can be supplied over time (in hours) and is usually specified over a 20-hour period. So a 100Ah battery should supply 5A for 20 hours, by which time the battery voltage will be down to 10.5V. At higher currents, the capacity will be less than 100Ah due to increased losses within the battery. Reserve capacity (RC) is specified in minutes. It specifies how many minutes the fully-charged battery can deliver 25A before the voltage drops to 10.5V. For example, a battery with an RC of 90 will supply 25A for 90 minutes (1.5 hours). This can be converted to Ah by multiplying RC (in this case 90) by the current (25A) and then dividing by 60 to convert from minutes to hours. Thus a battery with an RC of 90 has a capacity of 37.5Ah. In practice, the Ah capacity would be considerably higher if measured at the 20-hour rate. November 2004  37 38  Silicon Chip siliconchip.com.au Fig.4: the power section of the 3-Step Battery Charger. The output from the bridge rectifier (BR1) supplies the power controller which consists of transistors Q1-Q5. This circuit is controlled by op amp IC1b, in turn controlled by IC2a, IC2b and microcontroller IC5 (see Fig.5). For our battery charger, we use a pseudo remote sensing technique to do away with the need to have separate sensing leads. This method calculates the voltage drop produced by the charging current and subtracts this from the voltage measured inside the charger (it assumes a certain resistance in the battery leads and the current sensing resistor). The result is a very close approximation of the true voltage at the battery terminals. Specific battery parameters As mentioned, the Specific #1 and Specific #2 battery selections can be adjusted to suit particular battery types. The parameters that can be altered are the cyclic voltage, the float voltage and the temperature compensation. The cyclic voltage and float voltages can be obtained from the manufacturer and must be specified at 20°C (68°F). In order to change these parameters, jumper JP2 must be removed from inside the charger. When this is done and power is applied, the charger function will be off and the display will show SPECIFIC #1 on the first line and then 14.3V CYCLIC 20 Deg C on the second line. This is the initial cyclic voltage set for the Specific #1 battery at 20°C. You can then change the cyclic voltage using the “<” and “>” switches in 100mV steps over a range from 0.0V to 15.7V. Note that this range also allows charging a 6V battery. Pressing the set switch will cause the display to show the float voltage for the Specific #1 battery type. This will initially be 13.3V and can be set in 100mV steps over a range of 0.0V to 15.7V. Pressing the set switch again will show the temperature compensation value for the Specific #1 battery. Initially, the display will show -36mV/ Deg C. This can be changed in 1mV steps from 0mV/°C to -63mV/°C using the “<” and “>” switches. Pressing the set switch again will show the cyclic and float voltages and the temperature compensation value for the Specific #2 battery. Adjusting these is the same as changing the Specific #1 settings. When adjustments are complete, JP2 can be replaced inside the charger for normal operation. Block diagram Fig.3 shows the block diagram of the charger. The power transformer feeds siliconchip.com.au Temperature Compensation The temperature compensation required by manufacturers is usually shown as a graph of voltage versus temperature. You need to convert this to mV/°C. To do this, take the difference between the voltages at two different temperatures and divide by the temperature difference. For example, a battery graph may show the cyclic voltage at -10°C to be 15V and at 40°C it may 14.2V. So (14.2 - 15)/50 is -16mV/°C. Some graphs of batteries show the 18VAC to bridge rectifier BR1 and the resulting unfiltered DC is fed via a power controller to the battery via fuse F2. Should the battery be connected the wrong way around (reverse polarity), bridge rectifier BR2 will conduct and blow the 20A fuse (F2). The power controller section is itself controlled by a PIC microcontroller (IC5), in conjunction with IC3, IC4 and IC1. Circuit description The circuit for the 3-Step Battery Charger is split into two sections – Fig.4 (Power) and Fig.5 (Control). This is a linear design rather than switchmode. We opted for this approach in order to use more readily available components and to simplify construction, without the need for specialised high-frequency transformer assemblies, coils and high-frequency capacitors. A linear circuit is not as efficient as a switchmode design but it is easier to build and is more rugged. Also, much of the heat generated by the charger is due to losses in the main bridge rectifier and this would be much the same, regardless of whether we had used a switchmode or a linear design. Looking at Fig.4 (Power) first, the power transformer is a 300VA toroidal type feeding 18VAC to the bridge rectifier which then supplies the power controller which comprises transistors Q1-Q5, connected as a compound emitter follower. Q1 is a power Darlington and it drives the commoned bases of four TIP3055 NPN power transistors (Q2-Q5). These power transistors each have 0.1Ω emitter resistors to help equalise the load current. float temperature compensation to be slightly different to the cyclic compensation. In this case, the compensation will need to be a compromise between the two values. Note that it may be possible to obtain a better value, that is closer to the requirements for both voltages, if the graph is interpreted over a smaller temperature range, consistent with the temperature conditions under which you would expect to be using the charger. In operation, the emitters of transistors Q2-Q5 “follow” the voltage applied to the base of Q1 (hence the term “compound emitter follower”). Adjusting the base voltage on Q1 controls charging so that the higher the voltage on Q1’s base, the more the power transistors conduct and the greater the current into the battery. The 220nF capacitor between the base and collector of Q1 prevents bursts of oscillation that would otherwise occur as the transistors begin to conduct on each cycle of the pulsed DC voltage from the bridge rectifier. Op amp IC1b supplies the base current to Q1 via a 3.3kΩ limiting resistor. This amplifier has a gain of 6.6 to multiply the control voltage range at pin 5 from 0-5V to 0-33V. The 30V supply to IC1b and its limited output swing does restrict the range to more like 0-28V but this is more than enough to fully drive the output transistors. The 1µF capacitor across the 5.6kΩ feedback resistor provides rolloff above 28Hz to prevent op amp IC1b from oscillating. A 70°C thermostatic switch, TH2, provides over-temperature protection. This is mounted on the main heatsink and when it closes (when the temperature exceeds 70°C), it shunts base drive from IC1b to ground and this stops the charger from supplying current to the battery. Note that IC1b’s output is prevented from being directly shorted by a 3.3kΩ current limiting resistor. Current monitoring The charging current flow is measured by amplifying the voltage produced across a 0.005Ω resistor (R1) November 2004  39 40  Silicon Chip siliconchip.com.au Fig.5: the control section is based on PIC microcontroller IC5. It works in conjunction with IC3, a 4051 analog 1-of-8 selector which monitors the battery voltage, current and temperature (via Sensor 1). IC4 converts the selected analog data from IC3 into 8-bit serial data which is then processed by the microcontroller. The microcontroller produces the control signal for IC1b, drives the LCD module and processes the inputs from switches S1-S4. using IC1a which has a gain of 44. Filtering is included at the input and across the feedback path for IC1a, to convert the pulsating charge current to an average value. Hence, the 10μF capacitor at pin 3 filters the current by rolling off signal above 16Hz, while the 10μF capacitor across the 43kΩ feedback resistor rolls off frequencies above 0.37Hz. IC1a’s output is applied to pin 2 of the over-current comparator, IC2a, via a voltage divider comprising two 22kΩ resistors and a 100µF filter capacitor. The non-inverting input, pin 3, is connected to trimpot VR2. VR2 is adjusted so that IC2a’s output goes low when the charge current goes above 18A. When IC2a’s output goes low, it pulls pin 5 of IC1b low. This causes pin 7 of IC1b to go low, removing the drive to Q1 and to the battery. Over-voltage protection The battery voltage is monitored at point A on the circuit – ie, at the junction of the four 0.1Ω resistors (for Q2-Q5) – and fed via a voltage divider to pin 6 of comparator IC2b. This is compared to a reference voltage on pin 5, from the wiper of trimpot VR1. This is set so that IC2b’s output goes low when the battery voltage goes above 17V. The low output of IC2b will shut down the drive to Q1, as before. Note that IC2a and IC2b are comparators with open-collector outputs. When their outputs are off, they do not affect the drive to pin 5 of IC1b. Note also that when the output of IC2a or IC2b goes low to stop the drive to Q1 (via IC1b), the over-current or over-voltage condition will cease. As a result, the relevant comparator output will go open circuit again to restore the drive to Q1’s base. If the fault still exists, drive will again be removed and so this cycle will continue – ie, the charger will cycle on and off at a slow rate. Zener diode ZD3 provides a 5.1V reference supply for trimpots VR1 and VR2 and this is further reduced by a 3.3kΩ resistor so that each trimpot has a nominal 0-3V range. DC supply rails The 25V supply for IC2 and the fan is derived from the rectified output of BR1 via diode D1. This rail is filtered using a 2200µF 50V capacitor. Diodes D2 and D3 form a voltage doubler which is fed from the AC input siliconchip.com.au Specifications Bulk Charge: constant current charge at 25% of Ah. Absorption Phase: constant voltage charge at cyclic voltage until current drops to 2% of Ah or timeout of 2.5 hours (which ever comes first). Float Charge: constant voltage charge at float voltage. Equalisation: optional after absorption phase. Constant current at 5% of Ah for three hours. Equalisation switched off if temperature rises above 40°C. Battery Ah Settings: 4, 8, 12, 16, 22, 24, 30, 40, 60, 80, 90, 100, 125, 150, 175, 200, 225 & 250Ah. Battery Type: Lead Acid, Gel-Cell (Sealed Lead Acid or SLA), AGM (Absorbed Glass Mat) and Calcium Lead, plus adjustable settings with Specific #1 and Specific #2 battery selection. Lead Acid Parameters <at> 20°C: cyclic 14.2V, float 13.4V, compensation -20mV/°C. Gel-Cell Parameters <at> 20°C: cyclic 14.1V, float 13.3V, compensation -25mV/°C. AGM Parameters <at> 20°C: cyclic 14.4V, float 13.3V, compensation -36mV °C. Calcium/Lead Parameters <at> 20°C: cyclic 15.0V, float 13.8V, compensation -20mV/°C. Adjustable parameters (Specific #1 and #2): cyclic 0.0V to 15.7V in 100mV steps, float 0.0V to 15.7V in 100mV steps, compensation 0mV/°C to -63mV/°C in 1mV steps (changed with JP2 out). Low Battery Voltage Detection: 10.5V for 12V battery (5.2V for 6V battery). Low Battery Charge Current: 2% of Ah. Temperature Compensation: operates from -10°C to 99°C (voltage fixed at -10°C setting for temperatures below this). Open Circuit Temperature Probe Default: compensates assuming 40°C. Display shows (--). Temperature Measurement: display shows from –9°C to 99°C in 2°C steps. Temperatures below –9°C show as a LO. Temperatures above 99°C shown as (--). Display refreshes reading every 0.2 seconds. Voltage Measurement: from 0-16.0V with 100mV resolution. Display shows --.-V above 16V. Display refreshed every 0.2 seconds. Current Measurement: from 0-25.5A with 100mA resolution. Display readings refreshed approximately every 1 second. Fan Cut In Temperature: 50°C. Fan Cut Out Temperature: ~40°C. Over-Temperature Cutout: 70°C. Hardware Over-Voltage Limit: adjustable. Hardware Over-Current Limit: adjustable. Software Monitored Over Voltage Limit: 16V at charger output (not operational during equalisation). Software Monitored Over Current Limit: 20A. November 2004  41 This is the view inside the prototype. Most of the parts are mounted on three PC boards: a power board, a control board and a display board which mounts vertically behind the front panel. The assembly details are in Pt.2, next month. of the bridge rectifier via a 22µF capacitor. The voltage across the following 220µF capacitor is then limited to 30V by series-connected zener diodes ZD1 & ZD2 and a 10Ω resistor. Note that the two zener diodes are rated at 5W because the peak current through them is too high for 1W devices. The 10Ω resistor in series with the zener diodes is included to reduce the peak current. Why use a zener diode shunt rather than an adjustable 3-terminal regulator (such as an LM317) to obtain the 30V rail? Because the wide range of transformer loading means that an LM317 could not do the job. By the way, the reason we need a 30V supply for IC1 is so that IC1b can drive the base of Q1 above the 25V peak voltage of the unfiltered DC supplying the power transistors. The heatsink cooling fan is powered 42  Silicon Chip from the 25V supply rail via a 56Ω 5W resistor when ever the 50°C thermostat switch is closed. The 56Ω resistor reduces the fan supply to around 12V when the fan is running. Control circuit Fig.5 shows the control circuit which comprises IC3, IC4, PIC microcontroller IC5, the LCD module and associated components. IC3 is a 4051 one-of-eight analog switch. In our circuit, we use only three of the eight inputs. One selects the battery voltage at pin 2, the second selects the current signal at pin 1 and the third takes the temperature signal at pin 13. The voltage input comes from the positive battery terminal via 22kΩ and 10kΩ resistors which divide by a factor of 0.31. Voltages above 5V at pin 2 are clamped using D4, while voltages below 0V are clamped using D5. The latter is required to protect IC3 against reverse battery connection. The current signal comes directly from the output of IC1a (see Fig.4) via a 10kΩ series resistor. Battery temperature is measured using an LM335 (Sensor 1). This provides an output that is a nominal 10mV/°C. The offset voltage at 0°C is typically 2.73V. Trimpot VR3 divides the Sensor 1 output so the voltage can be set to vary by 9.8mV/°C. This adjustment is required to cater for individual variations in the output of these devices. The temperature, voltage and current signals to IC3 are selected by using the B and C inputs at pins 10 and 9, respectively. When the B and C inputs are set to 0V, the temperature signal (pin 13) is selected. When B is low and C is high, the current signal (pin 1) is selected and when B and C are both high, the voltage signal (pin 2) is selected. The selected signal is fed to IC4, an 8-bit analog-to-digital (A/D) converter. IC4 produces serial data at its pin 6 siliconchip.com.au output and this is fed to the RA4 input (pin 3) of PIC microcontroller IC5. The RA2 and RA3 lines from IC5 drive the clock and chip select inputs on IC4. IC5’s internal oscillator runs at 4MHz. This gives a timebase accuracy of about 2%, which is more than adequate for this application. LCD & pushbuttons The LCD module is driven from the RB4-RB7 outputs of IC5, while control over the display is provided by driving the Register Select (RS) and Enable (E) inputs at pins 4 and 6 respectively. The RB4-RB7 data lines also connect to switches S1-S4. When a switch is closed and its data line is high, it can pull the RA6 input (pin 15) high. Diodes D7-D9 are included to prevent the data lines from being shorted should more than one switch be pressed at a time. The RB0 and RB2 inputs provide the jumper options (JP1 and JP2). Normally, these inputs are pulled high via internal pullup resistors and pulled low if the relevant jumper is installed. JP1 is removed for auto start and JP2 is removed for the parameter change. In response to its stored software, IC5 produces a pulse-width modulation (PWM) output at pin 9. This swings between 0V and 5V at about 4kHz, with a duty cycle ranging from 100% (fully high at 5V) through to zero (fully low at 0V). By filtering this waveform, the resulting output will be a DC voltage which can be varied in steps of around 5mV (ie, 10-bit resolution). The filtering is provided by a 10kΩ resistor and 1µF capacitor and this becomes the control voltage fed to IC1b on the power circuit of Fig.4. The control circuit runs from a 5V supply derived from an LM317 adjustable regulator (REG1). It is fed from the +25V rail via a 330Ω resistor which reduces power dissipation in the regulator. Trimpot VR4 is set so that the output voltage is as close to 5V as possible. This calibrates the voltage and current readings measured by IC3. The chassis and circuit ground are connected together via a 470nF capacitor, included to shunt any noise signals present on the supply. Next month, we will give the full parts list, assembly details and set-up SC procedure. Looking For More Info? For more information on battery charging, readers can refer to “Motorhome Electrics – And Caravans Too!” by Collyn Rivers. We reviewed this in the February 2003 issue of SILICON CHIP. In this book, Collyn spells out the desirable charging methods for lead-acid batteries. Specifically, he makes note of the requirement to compensate charging with respect to temperature and with respect to battery chemistry. In Australia, temperature compensation is a mandatory requirement for a quality charger. This is because we have a wide range of temperatures across the continent and into Tasmania. Typically, temperatures can extend from the minus figures through to well above 40°C in the shade. The book is available from the Caravan & Motorhome Books, PO Box 3634, Broome, WA 6725. Stunning new Lumiled indoor/outdoor LED light fitting range D HIGH BRIGHTNESS D LONG LIFE D FULLY DIMMABLE D ENERGY EFFICIENT The range of LUMILED downlight fittings shown here have been designed for domestic, display, marine, mobile home and caravan applications. All fittings use Lumileds, which are: - Long life (typical 100,000 hours) - High efficiency, low power, low voltage - Vibration proof ARE BOTH ROOF, P R E H T WEA ERSIBLE! M SUB The OPLLBL series Black powder coated. The OPLLBR series Solid Brass. Both the OPLLBL and OPLLBR series are stand-alone types, for use either indoors or outdoors, are fully weatherproof and able to be fully submerged for pond application. The OPLLGW series White powder coated. This series is a ceiling type gimballed fitting and require a 57mm diameter cutout (MR11 size). Visit us at: www.prime-electronics.com.au PRIME ELECTRONICS siliconchip.com.au The OPLLFG series Gold outer rim with chrome inner finish. This series is a ceiling type fixed fitting and require a 51mm diameter cutout (MR11 size). The OPLLGC series Brushed Stainless Steel finish. This series is a ceiling type gimballed fitting and require a 57mm diameter cutout (MR11 size). The OPLLGG series Brushed Gold Finish This series is a ceiling type gimballed fitting and require a 57mm diameter cutout (MR11 size). Email us: sales<at>prime-electronics.com.au BRISBANE 22 Campbell Street Bowen Hills QLD 4006 Telephone: (07) 3252 7466 Facsimile: (07) 3252 2862 SOUTHPORT 11 Brickworks Cntr, Warehouse Rd Southport QLD 4215 Telephone: (07) 5531 2599 Facsimile: (07) 5571 0543 SYDNEY 185 Parramatta Road Homebush NSW 2140 Telephone: (02) 9704 9000 Facsimile: (02) 9746 1197 November 2004  43 SERVICEMAN'S LOG It’s time I bought a new TV set! It’s really time I got myself a new TV set and threw the old one out. Then again, maybe not – my rare 9-year-old set recently came in handy when an identical set came in for repair. My own personal TV at present is a 1995 Philips 32PW977/75 (GFL2.2A chassis) which is a fully-featured widescreen set. The reason I own it is that it has an annoying intermittent contrast level problem which over the years successive technicians – including myself – have failed to repair. However, the general consensus is that it’s the picture tube that’s causing the problem and this is far too expensive to replace. Most of the time though, the picture is perfectly acceptable to watch and it 44  Silicon Chip only plays up occasionally. Recently, I had an identical set come in for repair. This was somewhat surprising, as this fully-imported model is as expensive as it is rare. The fault with this particular set was no picture. When removing the back from this set, you must remember to unscrew and remove the sub-woofer cover first. That’s because the connecting lead is rather short and you can otherwise end up ripping it out of the PC board. This set, commensurate with its features, has a lot of electronics on board. This meant that the easiest way for me to locate the problem area was to initially try swapping modules with my own set. I did this and it didn’t take long to trace the problem to the CRT socket board (R). With my board in this set, the picture was excellent and the intermittent contrast fault did not move over from my set. An examination of the faulty board soon revealed that R3273 (10Ω) which supplies the 200V rail was open circuit, as was R3272 which supplies the 12V rail. The circuit shows the latter to be 6.8Ω but the set had an 18Ω unit fitted (by the factory) in this location. The reason these two fusible resistors had failed was because all three TDA6111AQ/N3 output ICs (7230, 7240 & 7250) were short circuit to ground. I ordered and replaced all these parts and then fitted the board to my own set to test it. Surprisingly, the intermittent low contrast problem I previously had was now suddenly permanently low contrast. What’s more, when I swapped the boards over, my set was still permanently suffering from low contrast. My next step was to check the BC-INFO (Beam Current) line. This measured 5.2V, which is roughly what it is supposed to be. However, the EHTINFO line (beam limiting from the flyback transformer) measured 0V and a quick check with an ohmmeter indicated that this line was short circuited directly to the chassis ground. Now this line also goes directly to the CRT aquadag and disconnecting the lead (plug R35) from this to the CRT socket indicated that the short was actually between the tube and chassis. As a result, I disconnected all the earth leads between siliconchip.com.au Items Covered This Month • • • • • • Philips 32PW977/75 TV set (GFL2.2A chassis) JVC video cassette recorder JVC AV-28S4E TV set (MXIV chassis) Telefunken SDX290 Hitachi HMV-8300 Stereo Amplifier NAD 317 Stereo Amplifier the chassis and the picture tube (in fact, all the leads I could see) but the meter still showed a short circuit between the aquadag and the chassis. How could this be? To the naked eye, the tube looked completely isolated from the TV chassis but the meter was telling me the opposite. As a result, I cast my net wider and examined the CRT mounting brackets and the loudspeakers but nothing immediately caught my eye. I then went through the motions of completely isolating everything from the front shell of the cabinet and the TV chassis. I unplugged the righthand set of loudspeakers while watching the meter – no change. However, when I unplugged the lefthand set of speakers, the short suddenly cleared. So how was this possible if there is absolutely no connection between siliconchip.com.au the tube and the speakers? Well, of course there had to be. The set has two elliptical speakers on each side plus a tweeter and the tweeters are connected via a 4.7µF 50V bipolar capacitor. And as I subsequently discovered, the lefthand side capacitor was tucked down hard between the speakers and the tube, with one of its leads touching the rim-band of the tube. Moving the capacitor just a fraction was enough to clear the short (the impedance of the tweeter is only 6Ω to ground), which accounted for why it was intermittent. Reconnecting everything brought the EHT-INFO line up to 9V for zero beam current (black) and 5V for 3mA (peak white). And the contrast was now strong and steady. Just why the other set destroyed its video amplifier IC is hard to determine, as the picture tube measured perfectly (no intermittent shorts) with the analyser. One possible reason is that the SCAVEM board shorted against the CRT socket panel. This board is held on with a plastic band around the CRT neck and this band fractures with age and heat. The slow JVC video An old friend of mine brought in his beloved JVC video complaining about intermittent no or slow rewind. Having done many of these over the years, I said I could fix it for him. The problem is caused by dried-up grease in the idler clutch assembly and the fix is easy: remove the old grease, clean the area, re-lubricate the assembly and reassemble everything. To do this, I first had to remove the deck, which isn’t difficult, after which November 2004  45 Serviceman’s Log – continued the job was quite straightforward apart from reconnecting a couple of the connectors. However, I was amazed to find when I switched it on afterwards that there was no display. This was because when I had re-inserted one of the worn flat ribbon cables, one of the conductors had bent back and shorted out. That was easily fixed but then I noticed that the playback picture was snowy, as though the heads were faulty or worn. I was sure I hadn’t damaged the heads in any way but the envelope waveform on the CRO was awful – so I quickly replaced the heads with those from another machine but the problem remained the same. Feeling somewhat miffed by this, I pulled the deck out again and examined the head assembly. And when I removed the head amplifier plug, I noticed that not all the pins were level – one was sitting 1mm lower than the others. Examining this more closely, I found it had been pushed through the board and broken the solder land to the copper (the solder is all that holds it 46  Silicon Chip in place). I resoldered it and pushed the pin through before using hot melt glue to keep it in place. I then reassembled everything and this time it all worked fine. What I should have done in the first place was sell my mate a new video. I never learn. The old JVC set I was called out to a 1994 JVC AV28S4E (MXIV chassis), its owner complaining of intermittent (at first) and now no vertical deflection (horizontal white line) before the set went dead. Now I had never seen this model before but fortunately managed to bludge a circuit off a mate of mine before calling around. I wouldn’t normally have agreed to a house call on a 10-year-old set such as this but logistics and hunger forced me to have a go. The only advice my friend (a JVC technician) gave me when he lent me the circuit was watch for the on/ off switch shaft which, apparently, is really easy to break when the set is in the service position. It didn’t take long to work out why the set was dead. Q521 (BU508AFI) – the line output transistor – was short circuit and of course I didn’t have one with me. I could go back to the workshop and get one but in the end I decided to take the chassis with me. I ordered and fitted the correct transistor when it arrived but I had no idea as to why the original transistor had failed. Nor did I know what was causing the vertical deflection problem. Examining the chassis, I noticed that C543 – a 2200µF 16V electrolytic capacitor – looked suspect. Its heatshrink covering had been shrunk by excessive heat and so it was replaced. This is the main smoothing capacitor for the 12V rail. Of course, the flyback transformer could also have failed but my shorted turns meter suggested it was OK. I then checked for and soldered miscellaneous dry joints, especially around the crystals to the jungle IC (IC201), which can cause intermittent drive pulses and destroy the line output transistor as in other JVC models. I also found a dry joint underneath some glue at the junction of C508 and C509, which are part of the AFC filter circuits. And I replaced filter capacitor C514 (10µF 50V), which is on the 15V supply to the horizontal drive transformer. Now what to do about the vertical deflection stages? I decided to play safe and change anything that might be likely to cause a problem. After all, the parts are cheap and the labour isn’t, so now was the easiest time to change everything in sight. As a result, I replaced IC441 (TDA 3654) and electrolytic capacitors C443, C444, C446, C448, C467 and C542 – ie, all the electrolytics in the vertical output stage. When I returned with the chassis, I managed to refit everything back together again without breaking the power switch. And because of space restrictions and the need to refit AV leads, I had to completely reassemble the set and fit it back into its entertainment centre before switching it on. It really was a relief to see the set come on with a fully-scanned picture. However, after a few minutes, I did notice a problem – one colour was missing, which was annoying. When I removed the back again, I found that this was due to a dry joint on the CRT siliconchip.com.au panel to one of the output transistors. Resoldering this finally restored the set to full operation. The dead Telefunken I sold a secondhand Telefunken SDX290 (Thompson ICC7000+) TV set some years ago to Frank Rogers, a young man in his late twenties who works in the city. Recently, he phoned to say his set had died and just prior to that he could hear “crackling” and smell acrid smoke. From his description it sounded like the flyback transformer had failed, especially as he lived near the beach. He didn’t want to spend much on it (have you ever met anyone wanting to spend money on repairs?), so I suggested he bring the set in and I would check it out. Frank jumped at this and said he would be round directly. Well, actually he didn’t “rock up” for a couple of hours (and he just lives around the corner) but when he did, his face was a picture – a mixture of sheepishness and anger. Apparently, he had had an accident on the way here. He had placed the set in the back of his station wagon and in his eagerness to get here had reversed really quickly down his driveway before stopping to turn and drive up the road. The problem was that in his haste, he hadn’t closed the tailgate properly. So when the car stopped abruptly, the set didn’t. As a result, the tailgate opened and the set tumbled out onto the road! Being of solid Teutonic construction, the cabinet didn’t break but both it and the tube sustained deep scratches. And that meant that Shauna, his wife, no longer wanted his pride and joy back in their lounge room, so he donated the wreck to me. Being curious, I removed the back and checked the set out. The flyback transformer was OK but the horizontal coupling capacitor – CW01 0.68µF 250V (mounted on sub-board DFH7070) – had failed big time. Replacing it fixed the picture and sound perfectly but nothing could be done about the deep scratches. I tried asking a few local glaziers about polishing out the scratches on the front of the picture tube but no-one would touch it with a barge pole – they wouldn’t even look at it. This is a perennial problem for me as often I get tubes with scratches and as yet, I haven’t found a satisfactory method of buffing them out. Of course, I didn’t phone Frank back to tell him that the cost of the repair would have been quite minor – that really would have been rubbing salt into an already gaping wound. Silicon Chip Binders $12. REAL VALUE A T 95 PLUS P& P H S ILICON C HIP logo printed in gold-coloured lettering on spine & cover H Buy five and get them postage free! Standards conversion A Panasonic TV from Brazil came in to be modified so that it would work in Australia. In the old parlance, CCIR System M is a mixture of American and European TV systems. It uses the American channel frequencies and spacing, plus 525 lines and 60Hz, and the German PAL-D colour system. Its usable voltage range is from 100V to 250V AC. Modifying it to work in Australia (System B/G) is fairly straightforward until you get to the colour system. In Brazil, the sub-carrier is 3.576MHz, whereas we are 4.43MHz, so we had no colour. Changing the ceramic filters for the RF, IF and decoder section was relatively siliconchip.com.au Price: $A12.95 plus $7 p&p per order. Available only in Australia. Buy five & get them postage free! Just fill in the handy order form in this issue; or fax (02) 9979 6503; or ring (02) 9979 5644 & quote your credit card number. Silicon Chip Publications, PO Box 139, Collaroy 2097 November 2004  47 Serviceman’s Log – continued easy but trying to get the jungle IC to lock into colour finally defeated us, as it requires changes to the microprocessor and EEPROM to switch the multiplier/divider connected to the 16MHz reference crystal. In the end, the work-around was to get a digital set top box with colour difference outputs that could plug into the DVD input sockets. Dead Hitachi amplifier A dead 1997 Hitachi 200 watt “Dynaharmony” series E amplifier (HMV8300) was brought in for repair. The reason it was dead was because the protection circuit had been enabled, as the left channel had a 15V DC output offset voltage. The power supply was giving the correct voltages at ±39V, ±95.8V, 14.7V and 10.6V. Careful measurements using a multimeter then revealed that R711 (100Ω) was open circuit. Unfortunately, replacing it and then powering up this big amplifier with a 100W light globe in series with the AC input didn’t fix the problem. This time, the offset voltage was -4V but at least the globe didn’t light up, so there didn’t appear to be any major faults that could cause catastrophic damage. Further measurements using a multimeter then showed that R710 measured 1.5kΩ, whereas it should have been 100Ω. Hoping that this would solve the riddle, I replaced it and switched the amplifier on – forgetting to put the safety globe in circuit. Big mistake – after the smoke had cleared, I found I had blown Q714, Q715 and Q710, all expensive output transistors. When I got back to square one again, I switched on but this time with the globe in place. The output offset was still at -4V and the globe showed that too much current was being drawn. I then found that the output stage bias was too high, at 200mV instead of 10mV. As a result, I took a closer look at the Bias Control/Idle Current Adjust area of the circuit. And I hit pay-dirt – a 12V zener diode (CR721L) on the other side of the board was short circuit. Replacing this finally fixed the amplifier. 48  Silicon Chip While I was at it, I decided that it would be a good idea to also examine the righthand channel of the amplifier. This revealed that the same two resistors were also high in this channel, even though it was still fully functional. My theory is that the lefthand channel’s 100Ω fusible resistors are what caused the zener diode to fail. As a result, they were replaced in the righthand channel as well, to ensure long-term reliability. Another audio amplifier Another 1997 amplifier, this time an English-made 80-watt NAD 317 (worth about A$1200), was also brought in. And like the Hitachi unit, it too had a protection problem. In this case, the protection circuit was being triggered due to a 6V DC output offset in the lefthand channel. Unfortunately, this time I had no circuit diagram, which meant it was going to be difficult, but at least I had one good channel to compare it with. I began by checking the power supply. This revealed unregulated ±90V rails which were then regulated down to ± 55V, 52V and -12V. These figures all seemed perfectly reasonable at the time. The DC offset for the righthand channel was 0V which is correct, while and the lefthand channel was at +6V as previously stated. My next step was to check all the transistors and I even replaced the small signal transistors in case of intermittent noise due to breakdown. However, this made no difference and I finally realised that I needed the circuit diagram to make further progress. As a result, I ordered the service manual and when it arrived, I immediately realised that the power supply voltages were incorrect – even though one channel was still working correctly. There should have been ±52V rails instead of +52V and -12V. From this information, I found a 100Ω resistor (not marked on the circuit) that was open circuit. This had probably failed due to a large number of leaky capacitors in the power supply (around 20, in fact). I replaced all these and for a while did have sound coming out of the amplifier but then the slow muting circuit cut in intermittently. I spent a very long time trying to fix this new fault and get this simple circuit to work. The circuit uses IC202 (TA7317) and its output at pin 6 drives, via two thermistors, a relay and Q208 (2SC2240). This, in turn, drives Q207 (2SA970) via a time-constant capacitor (C222), then Q206 and Q205. These then drive the “Protect-On” LED and muting transistors Q101 and Q102 – ie, the muting transistors for each channel. The problem lay around Q207, which was being randomly switched on. This transistor appeared to be still on even when there was only 0.07-0.055V varying between its base and emitter. However, hitting any component with freezer would make the circuit work. In the end, I replaced all the components in this circuit and it still kept playing up! Even replacing or shorting Q208 made no difference. It’s the economy, stupid After spending a prodigious amount of time trying to resolve this problem, it reached the stage of being well beyond economic repair. As a workaround, I simply removed the slow switch-on muting circuit transistor (Q207), resulting in a slight audible click when the amplifier was turned on or off. This wasn’t really a big deal and at least the rest of the amplifier now worked! Sometimes you just have a bad hair day – this was one! It’s funny how simple circuits are often more troublesome than complex ones. Of course, it’s possible that the transistors, which have a GR suffix, may require higher gain than the ones I fitted and this may SC be critical in this circuit. siliconchip.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 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. 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Books: Aust. $10 per order; NZ: $AU12 per book; Elsewhere $AU18 per book OR PAYPAL (24/7) OR Use PayPal to pay silicon<at>siliconchip.com.au PHONE – (9-5, Mon-Fri) Call (02) 9939 3295 with your credit card details OR MAIL This form to PO Box 139, Collaroy NSW 2097 November 2004  65 *ALL ITEMS SUBJECT TO AVAILABILITY. PRICES VALID FOR MONTH OF MAGAZINE ISSUE ONLY. ALL PRICES IN AUSTRALIAN DOLLARS AND INCLUDE GST WHERE APPLICABLE. 11/04 The Driveway Sentry By JIM ROWE Here’s a low cost, easy to build and install sensor system for detecting moving vehicles like cars, trucks, tractors or other farm machinery. It can also be used to detect the opening and closing of metal gates and roller doors. U nlike other sensing systems that use light, heat or ultrasonic sound waves to detect motion, the Driveway Sentry operates by sensing small changes in the Earth’s magnetic field – the same magnetic field that is sensed by a compass. Since cars, trucks and similar vehicles contain a significant amount of ferrous metal (iron, steel etc), they inevitably produce small temporary 66  Silicon Chip changes in the Earth’s magnetic field when they move into or through an area. That’s how the Driveway Sentry detects them, using a special high-sensitivity shielded remote sensor unit. Because it doesn’t generate any sensing fields of its own, the Driveway Sensory produces no environmental pollution of any kind; it’s quite ‘clean’. Also, because it only senses moving iron and steel objects like vehicles, it is much more selective than other kinds of sensor. This makes it immune to false alarms from birds, dogs, cats, sheep, cattle and other animals, falling tree branches, rain and snow, people walking past and so on. At the same time it can be used to detect the movement of vehicles which siliconchip.com.au MAIN FEATURES Exit Delay: Allows the system to be switched to non-sensing ‘sleep mode’ for a period of about six minutes, to allow the owner’s vehicle to exit from the property without activating the Driveway Sentry. At the end of the Exit Delay period, the system returns to its movement sensing mode. Test Button: Allows the system to be manually triggered into ‘movement detected’ alarm mode, without having to drive a vehicle past the remote sensing unit. This makes system adjustment much easier and more convenient. be disabled if you prefer the system to respond silently. onds and a maximum of about 25 seconds. Relay Contacts: The Driveway Sentry control box includes a DPDT relay with two sets of changeover contacts. These are activated when the system detects movement, allowing the Sentry to be connected to security systems, telephone diallers, radio transmitters and so on. It can also be used to control mains lighting, electric gates or other equipment, via an external mains-rated relay. Probe Sensitivity Control: Allows the sensitivity of the Sentry’s remote sensing unit to be adjusted over a wide range, so it can be set for reliable vehicle (or gate or door) movement detection without being too sensitive and susceptible to false alarms. Piezo Buzzer: Produces a high-pitched sound to attract your attention when movement is detected. This sound can Alarm Duration Control: Allows the duration of the system’s ‘movement detected’ alarm mode to be adjusted between a minimum of two sec- contain very little ferrous metal – like aluminium trailers, boats and caravans - simply by attaching a strong magnet to the underside of their frame. The magnet ensures that if they’re moved past the Driveway Sentry’s remote sensor unit, the Earth’s magnetic field will be disturbed locally and the system will activate. The Driveway Sentry can also be used to detect the opening or closing of a ferrous metal gate, or a roller door made from the same material, simply by placing the remote sensor unit in the appropriate position. It can even be used to detect the opening and closing of non-ferrous (ie, timber or aluminium) gates or roller doors, again simply by attaching a magnet to them. In short, the Driveway Sentry has a multitude of motion-sensing uses around the home, farm or industrial facility. By the way, the remote sensor unit doesn’t have to be mounted directly under the driveway or gateway, so there’s no need to cut a trench in your concrete drive. It’s sufficiently sensitive to detect moving vehicles within a range of about 3-5 metres, so it will work quite well when buried in a shallow trench alongside the driveway or gateway. The system operates from 12V DC and draws very little current: less than 30mA when ‘armed’ and waiting, and no more than 70mA when it senses movement and is ‘alarmed’. This means it’s very economical and can easily be operated from a 12V battery and/or solar power, as an alternative to an AC plugpack supply. The Driveway Sentry has been developed by Jaycar Electronics, and as a result the kit will only be available from Jaycar. Low Power Consumption: Operates from 12V DC power, with a low current drain and power consumption – less than 70mA (0.84 watts), even in ‘movement detected’ alarm mode. This means that the system can be operated from a 12V battery and/or solar power in rural and other remote situations. Because the project’s remote sensing unit uses a special construction and involves many thousands of turns of fine wire, this will be supplied pre-built and sealed in a waterproof housing with 30m of special shielded cable attached. This should be sufficient to connect the sensor back to the Driveway Sentry in most home or business situations. However if you need to monitor vehicle movement much further away from your house or office (say at a remote entrance gate or machinery shed), its alarm outputs can be connected back to your main security system via a VHF or UHF radio link. How it works The heart of the Driveway Sentry is its remote sensor, which as we said has many thousands of turns of fine wire wound on a long rod of ‘soft’ iron. He’s the Sentry you don’t have to pay, feed or even be nice to . . . but he’s ready and rearing to go 24 hours a day! This photo shows the control box and behind that, the sensor which is buried in the ground alongside your driveway. siliconchip.com.au November 2004  67 68  Silicon Chip siliconchip.com.au 2004 SC  K A 7 IC3c IC3b 14 ZD1 16V 1W A K 1nF 10 4 C B E PN100 10nF 11 RS 27k 12 13 11 10k 10k 330nF 9 CT +1.4V K K A K B K A 9 10 560Ω 16V ZENER A 1N4004 A 1N4148 8 Vss IC3a 3 +6V 1nF 1k 100nF O13 3 2 1 +1.4V BALANCE VR1 1k 10T 33k IC4 4060B IC3d 100nF 68Ω 68Ω 10 RT 16 Vdd MR 470k 12 IC3: 4011B A K K A D1,D2: 1N4148 DRIVEWAY SENTRY LEDS 100nF 8 S2 5 6 100k 9 D3 1N4148 A K EXIT DELAY 100k C1 G C2 30m SCREENED 2-CORE CABLE FARADAY SHIELD SENSOR COIL E C 8 Q1 PN100 220k 2 7 6 220 µF 25V 5 3 100nF 8 A LED1 POWER K D4 1N4004 1 IC2 7555 4 100nF +3.0V 1k 220k ALARM DURATION 47 µF 25V RBLL 47k CON1 12V DC IN VR3 500k EXIT DELAY λ LED2 470nF 470k IC1c 4 IC1: LM324 K λ A 1k 12 13 11 IC1d 470 µF 25V IN OUT GND E C A B +6V E C 7 TRIGGER IC1b 100nF RELAY1 100Ω 47 µF 16V Q2 PN100 K 180k 5 6 68k PIEZO BUZZER 100Ω Q3 PN100 – + REG1 7806 4.7k +11.4V B TEST S1 +4.4V 1k PROBE SENSITIVITY D5 1N4004 10k 14 VR2 500k LK1 BUZZER ON/OFF 4.7k 470nF +6V OUT GND IN 7806 NO COM NC NO COM NC +11.4V S2 EXIT DELAY ZD1 C2 G COM NC NO NO NC COM C1 NO NC POWER 100Ω 1k PIEZO BUZZER + 16V 10k 68Ω 1nF 100nF 4148 D1 D2 4148 68Ω 1k NO REG1 7806 47 µF a level where they are capable of being applied to IC1b, which compares them with a reference voltage of +4.4V from the voltage divider formed by the 68kW and 180kW resistors. When the peak value of the amplified sensor signals exceeds the +4.4V reference level, the output of comparator IC1b switches low. This negative-going pulse is used to trigger IC2, a 7555 timer IC configured as a one-shot. The output of IC2 (pin 3) then switches high, for a time period set by the RC time constant connected to pins 6 and 7. Trimpot VR3 allows you to adjust this alarm duration time between about two and 25 seconds. When IC2 triggers on, it switches on transistor Q3 and operates the relay. The relay contacts can then be used CON1 LED1 + 470 µF 25V 1N4004 COM ALARM TIME 33k 10k Q2 PN100 100Ω NC COIL LK1 100nF MKT 100nF NO 47k 100k 100nF LED2 NC RELAY1 4.7k BUZ/NOBUZ 560Ω Q1 PN100 Q3 PN100 D4 VR3 500k EXIT DELAY 1k 470nF 1k IC2 7555 4011B 10k 100nF 100nF 100k 4148 D3 100nF 27k 470k + 47 µF LL + 330nF IC3 100nF VR1 PROBE SENSITIVITY 10nF MKT IC4 4060B IC1 LM324 D5 1N4004 NC 470k 220k 4.7k 1k 180k 68k 220k 4002 C NO 1nF 100nF 220 µF COM This makes the coil very sensitive to small changes in the Earth’s magnetic field, of the type produced by a vehicle moving nearby. As a result of the magnetic field changes, the coil generates tiny low frequency AC voltages, and it’s these that are fed back to the Control Box via twin shielded cable. They are then amplified and used to trigger the alarm circuit. Because the sensor coil also tends to pick up a significant amount of electrical noise and mains hum, it must be fitted with a Faraday shield. This is a thin sheet of metal foil encasing the coil, providing it with an electrostatic shield (without also forming a shorted turn). The shield is connected back to the Control Box ground via the cable screening braid. The full circuit is shown in Fig.1. Inside the box, the small voltages induced in the sensor coil are amplified by about 470 times in a DC amplifier stage using IC1c – one section of an LM324 quad op-amp. Because of the high gain, this stage is provided with fine manual control over bias balancing, using 10-turn trimpot VR1. Diodes D1 and D2, along with zener diode ZD1 are used to protect IC1c from blocking or damage caused by induced voltage ‘spikes’. The output from IC1c is further amplified by IC1d, configured as an AC amplifier stage with gain adjustable between about 5 and 500 times using trimpot VR2. This brings the peak amplitude of the amplified sensor coil signals up to siliconchip.com.au 470nF YRTNES YAWEVIRD VR2 500k S1 TEST 100nF + Fig. 1 (left): the complete circuit diagram, and Fig.2 (right): the PC board overlay. As you can see, various size piezo buzzers can be accommodated on this board. Note the comments about the relay in the text: neither its contacts nor the PC board tracks are rated to handle 240VAC – however, it can be used to switch an external 240VAC rated relay. SENSOR COIL CONNECTIONS RELAY CONTACTS A RELAY CONTACTS B NOMINAL 12VDC INPUT to switch power to a siren, turn on security lights or trigger your main security system. At the same time, the high level on pin 3 of IC2 can be used to turn on transistor Q2 which controls the small piezo buzzer mounted in the Driveway Sentry control box. If you don’t want this internal buzzer to sound, it can be disabled by moving link LK1 over to the earthy side. Note that pushbutton switch S1 can be used to temporarily ground the positive input of comparator IC1b. This forces the output of IC1b low, triggering IC2 in the same way as a signal peak from IC1d. So S1 provides a handy Test function, allowing you to do things like adjust the alarm duration without The completed PC board, as mounted in the jiffy box. November 2004  69 Parts List – Driveway Sentry 1 PC board, code DRIVSENT, 133 x 83mm 1 Jiffy box, UB1 size (158 x 95 x 53mm) 1 Magnetic Sensor potted coil assembly (Jaycar) 1 12V DPDT relay, 5A contact rating 1 piezo buzzer 2 DPDT pushbutton switches (S1,S2) 3 3-way terminal blocks, PC-mounting 1 2.5mm concentric power connector, PC-mounting 1 3-pin SIL header strip, with jumper shunt 1 19mm square U-shaped heatsink 4 M3 tapped spacers, 25mm long 4 M3 machine screws, 9mm long countersunk head 5 M3 machine screws, 9mm long round head 1 M3 hex nut and star lockwasher Semiconductors 1 LM324 quad op amp (IC1) 1 7555 CMOS timer (IC2) 1 4011B quad NAND gate (IC3) 1 4060B binary counter (IC4) 1 7806 +6V regulator (REG1) 3 PN100 NPN transistors (Q1,Q2,Q3) 1 16V 1W zener diode (ZD1) 1 5mm green LED (LED1) 1 5mm red LED (LED2) 3 1N4148 silicon diodes (D1,D2,D3) 2 1N4004 1A silicon diodes (D4,D5) (SOIL) REMOTE SENSOR IN SHALLOW TRENCH ALONGSIDE DRIVEWAY 1 68kW 2 4.7kW WHERE TO GET THE KIT: This project was designed and developed for Jaycar Electronics, who own the copyright to the circuit, PC board and illustrations. A kit of parts will be available exclusively from all Jaycar Electronics stores shortly after this issue goes on sale. The kit (KC5402) has all components listed above, including the unique sensor coil and retails for $179.00 including GST. Contact your nearest Jaycar Electronics store or visit www.jaycar.com.au 70  Silicon Chip SOIL USED TO COVER SENSOR, HIDING IT AND CABLE DRIVEWAY Capacitors 1 470mF 25V RB electrolytic 1 220mF 25V RB electrolytic 1 47mF 16V RB electrolytic 1 47mF 25V RBLL electrolytic 2 470nF MKT polyester 1 330nF greencap or MKT 8 100nF multilayer monolithic ceramic 2 100nF MKT 1 10nF MKT 2 1nF disc ceramic Resistors (0.25W 1%) 2 470kW 2 220kW 1 180kW 2 100kW 1 47kW 1 33kW 1 27kW 3 10kW 4 1kW 1 560W 2 100W 2 68W 1 1kW trimpot, horizontal 10-turn (VR1) 2 500kW trimpots, horizontal (VR2,3) The remote sensor, potted inside its PVC pipe protective cover. Don’t try to remove it – the chances are very high that you will damage or destroy it! The drawing below shows how the sensor can be located in a trench alongside the driveway – you don’t have to cut a hole in the concrete to use the Driveway Sentry. having to drive a vehicle near the remote sensor unit. All of the remaining circuitry around IC3 and IC4 is used to provide the Driveway Sentry’s ‘exit delay’ function. This operates quite simply by holding the reset pin (pin 4) of IC2 low for a fixed period of about six minutes, after power is first applied to the Driveway Sentry or after pushbutton S2 is pressed at any later time. With its reset pin held low, IC2 is prevented from triggering during that time, allowing you to drive out in your own vehicle before the Sentry is re-armed. The exit delay circuit consists of a simple R-S flipflop using IC3b and IC3c, two of the gates in a 4011B quad NAND gate. When power is first applied or when S2 is pressed, the flipflop is switched into its reset state (pin 4 low), by the temporary low on pin 8. This low is applied to the reset pin (12) of IC4, a 4060B oscillator/14-stage binary divider IC. IC4 is thus allowed to begin oscillating and counting. This proceeds for around six minutes, after which IC4’s pin 3 (output O13) finally drops to the low logic level. This negative-going edge is coupled via the 10nF capacitor back to pin 6 of IC3b, which switches the flipflop back into its set state. In this state pin 4 goes high, holding IC4 in its reset state and stopping its oscillator and counter. At the same time, gates IC3d and IC3a (used as inverters) apply a logic high to the reset pin of IC2, allowing it to be triggered again. So the Driveway Sentry is re-armed. Notice that during the exit delay time, there is a logic high on pin 10 of IC3c, the lower flipflop gate. This is used to turn on transistor Q1, which allows current to flow through LED2. This LED is therefore only illuminated during the exit delay period. The power supply section of the Driveway Sentry is straightforward. Diode D4 provides reverse polarity protection on the 12V DC input, while regulator REG1 provides siliconchip.com.au a stable +6V supply for all of the electronics apart from the relay. LED1 gives indication that the Driveway Sentry has +12V power and is operating. Construction Apart from the remote sensor unit, all of the Driveway Sentry’s components and circuitry are mounted on a small PC board measuring 133 x 83mm and coded DRIVSENT. It is mounted in a standard UB1 jiffy box measuring 158 x 95 x 55mm, which forms the control box. The remote sensor unit connects to it via the 30m shielded cable. Since the remote sensor unit will be supplied fully built up, you will only have to wire up the control box - ie, fit the components to the PC board. This should be quite straightforward if you use the PC board overlay diagram (Fig.2) and the internal photo as a guide. Begin assembly by fitting the two wire links to the board. These are near IC2 in the centre and they are both 0.4” long (so you can use ‘0W’ dummy resistors if you prefer). Also fit the three-way SIL header strip for LK1 at this time – it goes between IC2 and the relay location. Then fit the three 3-way terminal blocks, which go on the right-hand end of the board. The 2.5mm DC input socket can be fitted as well, down in the lower right-hand corner. Now fit the resistors. Follow these with the smaller unpolarised capacitors, then the larger unpolarised and polarised capacitors. Make sure you fit the latter with the correct orientation, as shown in the overlay diagram. Note that there are two different 47mF electrolytics: one a low leakage (RBLL) type, usually in a case with an orange coloured sleeve, and the other a standard RB type in a black sleeved case. The low leakage unit goes near IC2 in the centre of the board, while the standard electro goes just to the left of REG1. Next mount the three trimpots, the relay and the piezo buzzer. Note that the PC board provides multiple holes for the buzzer, to cope with different buzzer pin spacings. The two pushbutton switches can be fitted after this, but you may need to slightly enlarge the PC board holes for these with a jeweller’s file, to allow their lugs to pass through the board sufficiently for soldering. Begin fitting the semiconductors siliconchip.com.au The completed PC board mounted in a UB1 Jiffy Box. Note the hole and slot cut in the ends of the box – the hole (right) is for the plugpack mains adaptor, while the slot allows the wiring from the sensor unit and the wiring to external alarm/ controlled devices to enter the box. by adding the various diodes, making sure you fit them in the correct locations and with the correct polarity. Then fit the three transistors, watching their orientation also. Follow these with REG1, which is mounted horizontally with a 19mm U-shaped heatsink. Its three leads are bent downwards 6mm from the device body and soldered underneath. The regulator body is held firmly down in contact with the heatsink using a 9mm long M3 machine screw with a star lockwasher and M3 nut. The four DIL ICs are fitted next, making sure you fit each one the correct way around as shown in the overlay diagram. As three of the ICs are CMOS, take the usual precautions to minimise the risk of electrostatic damage. Use an earthed soldering iron, and ideally earth yourself before picking up these devices. Also solder their supply pins to the PC board pads first, before soldering the other pins. The final components to fit are the two LEDs, which are both 5mm types. The green LED fits in the LED1 position just below the relay, while the red LED fits in the LED2 position just above pushbutton S2. Both mount vertically with the lower surface of their body 20mm above the board, so they will protrude through matching holes in the box front panel when it’s assembled. They are also both orientated with their ‘flat’ side downwards, and their longer anode lead towards the top of the board. Your Driveway Sentry board assembly should now be complete, and ready for testing. Testing and setup For the initial testing, there’s no need to connect the remote sensor unit to the PC board assembly. Just connect a 330W resistor temporarily between terminals C1 and C2 at upper right on the board, as a passive ‘stand in’. Then connect a plugpack or another source of 12V DC to CON1, the board’s DC input connector at lower right. If all is well, both LEDs should immediately light – LED1 because power is present and LED2 because the exit delay timing circuit has already begun counting. LED2 should remain on for about six minutes after power-up, just as it should do after you press button S2. Next, connect a DMM to pin 8 of IC1, and measure the voltage. It should be between +2.5V and +3.0V. If it isn’t inside this range, adjust trimpot VR1 until it is. Now set trimpot VR3 to about midrange and check that link LK1 is in the ‘buzzer on’ position. Also wait until LED2 is off, showing that the exit delay circuit has timed out. Then press Test button S1, which should make the relay operate and the buzzer sound. If the buzzer operating time is not to your liking – ie, it’s too short or too long – this can be changed quite easily by adjusting trimpot VR3. The adjustNovember 2004  71 A couple of keyhole slots cut in the rear of the Jiffy Box makes it easy to mount the box on a wall. Naturally, these need to be cut before the PC board is installed in the box. ment range is from about two seconds up to about 25 seconds. The only other adjustment to be made to the Driveway Sentry is to vary the sensitivity of the sensor probe. This is done in much the same way as for the alarm duration, but by adjusting trimpot VR2. The adjustment must be done later though, when the system has been installed and the remote sensor unit connected. For the present, simply set VR2 to its midrange position. Final assembly The final step in building the Driveway Sentry is to fit the PC board assembly inside the main part of the box. It mounts via four 25mm long M3 tapped spacers, using four 9mm long M3 countersink head screws to fasten the spacers in the box, and four 9mm long M3 round head screws to attach the PC board. When the board is mounted inside the box the pushbuttons will protrude through matching holes in the front panel, as will the two LEDs. The Probe Sensitivity (VR2) and Alarm Duration (VR3) trimpots can also be adjusted using a small screwdriver through their labelled adjustment holes. A 10mm diameter hole in the righthand end of the box allows the 12V DC cable to enter, while an adjacent rectangular slot allows entry of the various sensor unit and relay contact cables. As you can see from the diagram of Fig.3, the rear of the box has two elongated holes to allow the completed control unit to be mounted on a wall using two 8G x 25mm self-tapping screws or similar. The screws should be fitted to the wall exactly 100mm apart, in horizontal alignment and 72  Silicon Chip screwed in with their heads only 2.5mm away from the wall. Mount the control box in a position where it’s unobtrusive, yet easy to access so you can press the Exit Delay button before leaving. Locating the sensor The remote sensor unit is housed in a sealed plastic tube 50mm in diameter and 370mm long. It’s designed to be placed in a shallow trench alongside your driveway, so that it’s out of sight while still being near any vehicles moving on the driveway. If there’s a steel-framed gate at the driveway entrance, you can mount the remote sensing unit under the area where the gate is swung open, so it will detect the gate being moved as well as a moving vehicle. Note that the remote sensing unit doesn’t have to be mounted directly under the driveway, because it’s quite sensitive. So there’s no need to cut a trench in your concrete drive – just bury the sensor a small distance down in a lawn or garden bed alongside the drive. The sensor is connected back to the control unit via its attached 30m long screened cable. The two inner wires of the cable connect to terminals C1 and C2, while the earthing screen connects to the centre ‘G’ terminal. There’s no need to dig a deep trench for the probe. It only needs to be about 100mm below the surface, where it should be hidden and protected from damage. The cable can be run back to the nearest building in a narrow trench of about the same depth. Sensitivity adjustment Once the sensor unit has been fitted in position and connected back to the control unit, you’re ready to make the final adjustment: probe sensitivity. As explained earlier this can’t be done using the Test button; it can only be done using a vehicle moving along the driveway, or someone opening or closing the gate or roller door for you. Trimpot VR2 is turned clockwise to make the probe more sensitive, or anticlockwise to make it less sensitive. The best setting is where the probe reliably detects the smallest moving vehicle likely to enter or leave via the driveway, without being more sensitive than this. If you simply adjust VR2 for maximum sensitivity (ie, fully clockwise), the Driveway Sentry may then be prone to giving ‘false alarms’ due to passing radio transmitters or mobile phones, or during electrical storms. Putting it to use When the Driveway Sentry is ‘armed’ and detects movement, it immediately produces an alarm sound from the buzzer and operates the relay. The relay contacts can be connected to another security system, so that when the relay operates this can initiate further action like triggering a loud siren, dialling a security firm, dialling your own mobile phone or whatever action you choose. Please note that the relay contacts in the Driveway Sentry control box are NOT rated for switching 240V AC mains power. So if you want to have the Sentry turn on high power floodlights or other mains-operated equipment when it detects vehicle or gate movement, you’ll need to do this via a second external relay with mains-rated contacts (or a mains-rated solid state relay). The Driveway Sentry’s relay contacts can activate the external relay, to control the mains-powered lighting or equipment. Jaycar can supply a mains-rated solid state relay which would be quite suitable for this: the SY-4080, which can switch up to 3A at 240V (ie, 720W). The main external connection options for the Driveway Sentry are illustrated in the diagram of Fig.3. As you can see it’s very easy to hook the Sentry up to a larger security system, using a length of two-wire cable. One wire connects to either COM terminal on the control box, and the other wire to either the NO (normally open) or NC (normally closed) terminal in the siliconchip.com.au CONNECT CORRESPONDING CONTACT PAIRS COM NC NO COM NC NO INPUTS 2 PHONE LINE 12VDC NC COM NO NO COM NC 1 TRIG PHONE DIALLER SECURITY SYSTEM DRIVEWAY SENTRY A DRIVEWAY SENTRY CONNECTING TO A SECURITY SYSTEM SOLID STATE RELAY NO NC COM B CONNECTING TO A PHONE DIALLER ESR2102400300 3–32 VDC INPUT 4 – + 3 MAINS PLUG & CABLE 3A 240VAC OUTPUT 2 1 ACTIVE (BROWN) WIRE TO FLOODLIGHTS OR SIREN, ETC DRIVEWAY SENTRY 0V C CONNECTING TO A SOLID-STATE RELAY FOR SWITCHING MAINSPOWERED LIGHTS, ETC. EARTH (GRN/YELLOW) WIRE +12V NEUTRAL (BLUE) WIRE INSULATE THESE RELAY PINS AND JOINTS WITH HEATSHRINK SLEEVING OR SIMILAR EARTH NEUTRAL ACTIVE (BROWN) WIRE ACTIVE Fig. 3: connecting the Driveway Sentry to various external devices. same group – depending on the security system input you connect it to at the other end. If the security system input expects NO contacts, connect to the NO terminal; if it expects NC contacts, connect to the NC terminal. Connecting the Sentry up to a phone dialler is just as easy. Again you simply use a two-wire cable, connecting it to a COM terminal and either of the matching NO or NC terminals depending on the type of contact action needed to trigger the dialler. When you want to connect the Driveway Sentry so it can switch on external floodlights or a high-power siren powered by the mains, this can be done by connecting one of the Sentry’s relay contact sets so that it can operate an SY-4080 solid state relay, or some other relay rated to switch 240V power. As you can see, the positive input (control) terminal of the solid state relay is connected to the +12V supply, while its negative input is connected to the NO terminal of the Sentry contacts. The COM terminal of the same set of contacts is then connected to 0V, so the solid state relay will be operated (turned on) when the Driveway Sentry detects a moving vehicle or gate. The solid state relay’s output connections are then used to switch 240V power to your siren or floodlights, etc. SC siliconchip.com.au 8G x 25mm SCREWS (WALL) 1 OFFER LARGE ENDS OF HOLES IN BOX REAR UP TO SCREWS, THEN SLIDE BOX DOWN TO FASTEN IT 2 DRIVEWAY SENTRY CONTROL BOX FRONT PANEL Fig.4: mounting the Driveway Sentry on a wall. November 2004  73 Control equipment from anywhere, any time, using SMS and an old Nokia mobile phone! – By Peter Smith SMS Controller Pt.2 L ast month, we described the circuit for the SMS Controller and gave the assembly details. This month, we tell you how to complete the circuit checking and describe how the unit is used. Having carried out the power supply checks described last month in Part 1, the next step is to check out the serial interface and the microcontroller. First, disconnect the power and insert IC1 and IC3 into their sockets. If the microcontroller needs to be programmed, then you should do that next. Refer to the “Microcontroller Programming” panel for more details on this. Next, install jumper shunts on JP4-JP7. These should always be in place when the inputs (IN1 - IN4) are not connected, otherwise the micro’s 74  Silicon Chip port pins will be “floating” in an indeterminate logic state. Conversely, remove all jumper shunts from JP1-JP3 if installed earlier and apply power. The “Comms Error” LED (LED1) should illuminate, while all other LEDs (except the “Power” LED) should be off. This indicates that the micro cannot communicate with the phone, which of course isn’t connected yet. However, it does tell us that the micro is doing what it should. Note: the very first time you apply power, all red LEDs may come on for one second and then go out, with just the “Comms Error” LED remaining on. This sequence indicates that the micro has automatically erased its on-board EEPROM, ready for programming. If you get a different result, the problem is most likely due to one or more pins of the micro having missed their sockets and bent underneath the chip. If bent pins aren’t the problem, then check out the oscillator circuit, consisting of crystal X1 and the two 22pF capacitors. If you have access to an oscilloscope, you can observe the operation of the oscillator on pin 18. In addition, check the voltage on the micro’s RESET input (pin 9). This pin should measure close to +5V during normal operation, going low only during power up and power down. The final step involves a quick checkout of the RS232 interface circuit. Measure the voltage between pin 2 of IC4 and ground and pin 6 of IC4 and siliconchip.com.au ground. You should get around +9.5V and -9.3V, respectively. These voltages are generated by the MAX232’s internal charge pumps, in conjunction with the four 1µF capacitors. If your board passes all the tests, you can now connect the data cable between your board and phone. Note that’s it’s a good idea to power off both devices when connecting and disconnecting this cable. Suitable case If desired, the completed module can be housed in a “UB1” size plastic jiffy box or similar, with a slot cut in the side of the box to accommodate the terminal block wiring. The mobile phone must be positioned at least 50cm from the controller and associated wiring so that RF energy from its antenna doesn’t interfere with the circuit operation. This is very important! If this separation cannot be attained in your application, then the controller must be housed in a metal case or shielded from the phone with a large metal plate. Alternatively, both the 5110 & 6110 models support connection of an external antenna, which would allow good separation and improve signal strength in some areas. Operational basics System operation is quite straightforward – when any of the digital inputs change state, the controller sends a pre-programmed SMS message to the nominated mobile number. Conversely, when you want to turn any of the outputs on or off, you send a message to the controller. The messages used in both directions are programmed during the setup procedure. This allows the use of messages related to the task at hand. For example, you might want to assign the message “pump” to turn on the first output and “nopump” to turn it off. This means that you don’t need to remember which output the pump is connected to or which state (high or low) is on or off. The controller also recognises a number of unique messages, called “in-built commands”, that can be sent from another mobile to program the system during setup, as well as modify system behaviour during normal operation. A summary of all these commands appears in Table.2. Before we look at how to set up the siliconchip.com.au On the 3310 model, the serial interface is accessible through a hole in the rear of the case, underneath the battery. The data cable is terminated with a plastic head assembly that includes a set of spring-loaded contacts as well as tabs to retain the battery that it partly displaces. controller, let’s look at each command in detail. In-built commands ACKON – this command forces the controller to respond to every message that it receives. If a received message is deemed valid, the controller responds with “OK”. If a message is unknown, the response is “bad cmd”. ACKOFF – the opposite of ACKON. All further acknowledgments are disabled. CHARGE{number} – this command allows you to modify the battery charging parameters, dependent on the model of phone in use. For the 5110 & 6110, the {number} value defines the battery level at which the on-board charger is switched on. Only values between 0 and 4 are valid. A value of 4 instructs the controller to continually charge the phone and is therefore not recommended. The default level is 1. For the 3210 & 3110, a timed charge/ discharge scheme is used instead, as battery level information is not available to the controller. The {number} value defines the charge time in minutes, with the discharge time being fixed at 8 hours. Only values between 10 and 240 are valid. The default charge time is 40 minutes. COUNT – Use this command to get the total number of messages sent and received by the controller, as well as the firmware version number. The returned message is in the format “r=nnnnn s=nnnnn v=nn.nn”, where “r” and “s” are the total number of received and sent messages, respectively. DIS{string} – in some situations, you may not want to be informed when a particular input changes state but still want to receive notification on the remaining inputs. An example of this might be when one sector of an alarm system is faulty and has been isolated. Using this command, you can disable notification on either or both states of any input. For example, suppose a message of “SECTOR1ALARM” is programmed to be sent when an input goes low and a complementary message of “SECTOR1IDLE” is programmed to November 2004  75 The 3210 interface is also accessible under the rear cover but unlike the 3310, there’s no need to remove the battery. Once in place, the connector and cable extend at right angles from the rear of the phone, which may make mounting awkward in some cases. be sent when it returns high. To stop receiving these messages each time the input toggles, you could send the commands “DISSECTOR1ALARM” followed by “DISSECTOR1IDLE”. EN{string} – the opposite of DIS{string}, this command reinstates notification on the input and state designated by {string}. LOGIN{pass} – essentially, this command tells the controller your current mobile phone number. You don’t actually need to enter the number, as it’s automatically gleaned from the incoming message. All messages are forwarded to the mobile phone that sent the last LOGIN command, which remains valid until another LOGIN or LOGOUT command is received. If a password had been set, it must immediately follow the LOGIN command. An exception to this is in programming mode (JP3 in), where password checking is not performed. LOGOUT – this command disables all outgoing messages. It’s wise to send this command to the controller before you switch off your phone. If your phone’s battery goes flat, or it’s stolen or misplaced, use a friend’s phone to first LOGIN and then LOGOUT. If you don’t, a malfunctioning system could see you rack up a phone bill of astronomical proportions – a compelling reason to use only a prepaid plan for the phone connected to the controller (see panel in Pt.1)! PASS{string} – sets a new password of 1-8 characters long. Passwords longer than 8 characters elicit a “bad pass” response. The initial password is programmed during the setup procedure. Once set, it can be changed at any time but only from the currently logged-in phone (see LOGIN command). Table 2: Command Summary Command Function ACKON Enable acknowledge messages ACKOFF Disable acknowledge messages CHARGE{number} Modify battery charge level (5110 & 6110) or charge time (3210 & 3310) COUNT Get SMS sent & received counters & firmware version number DIS{string} Disable state change messages on input defined by {string} EN{string} Enable state change messages on input defined by {string} LOGIN Enable message transmissions to your current mobile number LOGOUT Disable further message transmissions to your mobile PASS{string} Set new password to {string} (8 characters max.) STAT Get snapshot of digital inputs & open-collector outputs The following commands are valid only in programming mode (JP3 in): IN{n}{L}{message} Define the message the controller sends when input {n} goes low IN{n}{H}{message} Define the message the controller sends when input {n} goes high OUT{n}{L}{message} Define the message you send to drive output {n} low OUT{n}{H}{message} Define the message you send to drive output {n} high OUT{n}{P}{message} Define the message you send to pulse output {n} low Here’s a summary of the commands recognised by the controller. The curly braces are used here for clarity and should not be included in your messages. Note: do not use spaces after command words. 76  Silicon Chip siliconchip.com.au A complete lineup of the supported models, from left to right: 5110, 6110, 3210 and 3310. STAT – returns the current state of the digital input and open-collector output ports. The displayed format is “XXXX YYYYYYYY”, where “X” and “Y” are “H” for logic high or “L” for logic low. The input port is displayed first, followed by the output port, with the most-significant bits (IN4 & OUT8) displayed first. For the output port, an “H” (high) indicates the driver is switched off, whereas an “L” (low) indicates it in on. Note that external circuits may invert this logic. A response from the STAT command looks like this: “HHLH HLHHHHHH”. In this case, IN2 is low and IN1, IN3 & IN4 are high. On the output side, OUT7 in on (low) and all other drivers are off (high). The following commands operate only in programming mode (JP3 in): IN{n}{L}{message} – defines the message that will be sent by the controller when input {n} goes low. For example, suppose you’ve connected a switch to the first input (IN1), as shown in Fig.7(b). When the switch is closed, the input changes state from a logic high (+5V) to a logic low (0V). To receive the message “SWITCH CLOSED”, the required command would be IN1LSWITCH CLOSED. Of course, you can use any message you like, as long as it’s no more than 16 characters long. siliconchip.com.au IN{n}{H}{message} – defines the message that will be sent by the controller when input {n} goes high. Using the previous example, to receive the message “SWITCH OPEN” when the first input (IN1) changes from a logic low to a logic high, the required command would be: IN1HSWITCH OPEN. OUT{n}{L}{message} – defines the message that you send to the controller to drive output {n} low. For example, suppose you’ve connected a relay to OUT1, as shown in Fig.6(a). A low on this output grounds one end of the relay coil, switching it on. Assuming you want to use the message “RELAY ON”, the required command would be OUT1LRELAY ON. OUT{n}{H}{message} – defines the message that you send to the controller to drive output {n} high. From the previous example, to switch the relay off with the message “RELAY OFF”, the required command would be OUT1HRELAY OFF. OUT{n}{P}{message} – defines the message that you send to the controller to pulse output {n}. When the controller receives this message, the specified output will be driven low for one second, after which it returns high. Again from the previous examples, to pulse a relay on OUT1 using the message “PULSE RELAY”, the required command would be OUT1PPULSE RELAY. It’s important to note that when any output is defined as a “pulsed” output, you cannot also define it with the OUT{n}{L} or OUT{n}{H} commands. Message syntax Messages used in the “IN” and “OUT” commands can be composed from any characters in the available repertoire but the total length must be limited to 16 characters. Longer messages are automatically truncated. Spaces can be used in the body of messages but not adjacent to the command or password strings (ie, DO NOT use spaces after command words). In addition, all user-defined messages, including the password, are case sensitive. This is a trap for the unwary; “PUMP ON” and “pump on” are not the same message! Inbuilt commands, on the other hand, are not case sensitive. Finally, your messages must not start with the in-built command words ACKON, ACKOFF, CHARGE, COUNT, DIS, EN, LOGIN, LOGOUT, PASS or STAT. Example setup Let’s look at a fictitious system setup so that you can see how it all works. The specifications for this system are as follows: • All commands to the controller must be acknowledged. • The system is to be password proNovember 2004  77 LED Indicators Five LEDs are provided to indicate system status; four red (LED1 - LED4) and one green (LED5). The red LEDs indicate error conditions, so during normal operation, none of them should be on. LED1 – Comms Error: when illuminated, this LED indicates a controller to phone communications problem. Normally, it comes on for 6 seconds after power on and then goes out. If it doesn’t go out, check for problems with the controller to phone cable connection. In addition, check that phone security (PIN) has been disabled and that the phone comes up ready for use at power on. LED2 – No Service: indicates that the phone is not registered within the mobile network (check signal strength) or that an outgoing message has been disallowed. The latter is typically due to an empty pre-paid account. tected. The initial password will be “REDDWARF”. • A relay is connected to OUT1, as shown in Fig.6(a). The relay controls a pump motor. • The relay is to be switched on by sending “PUMP ON” to the controller. • The relay is to be switched off by sending “PUMP OFF” to the controller. • A switch is connected to IN1, as shown in Fig.7(b). The switch detects water level in a tank. • When the switch closes, we want to receive the message “TANK OVERFLOW”. • When the switch opens, we want to receive the message “LEVEL NORMAL”. We start in programming mode by installing a jumper on JP3 and powering up. After the “Comms Error” LED goes out (about 6 seconds), we can send our programming commands from a second mobile phone, as follows: LOGIN (the green LED illuminates) ACKON PASSREDDWARF OUT1LPUMP ON OUT1HPUMP OFF IN1LTANK OVERFLOW 78  Silicon Chip Note that although your service provider will block outgoing messages when an account expires, most still allow inbound messages for a certain length of time. LED3 – Send Error: when illuminated, the controller has failed to send one or more messages. This can be caused by a variety of problems, including mobile network overload, momentary signal dropout, an empty pre-paid account, phone malfunction or an intermittent controller to phone connection. LED4 – Delete Error: indicates that the controller cannot delete a message from SIM memory. Cycle the phone power to correct this problem. If the error persists, then there may be a problem with the SIM card or phone. LED5 – In Use: this LED comes on when you login to the system and goes out when you logout. IN1HLEVEL NORMAL This completes the programming, so JP3 must now be removed, returning the system to operating mode. We can now control the pump by “SMSing” the following messages to the controller: PUMP ON (switch the pump on) PUMP OFF (switch the pump off) If our imaginary tank overflows and the switch closes, we’ll receive the message: TANK OVERFLOW When the level subsides and the switch opens, we’ll receive the message: LEVEL NORMAL Now suppose we don’t want to receive the “LEVEL NORMAL” message again. Instead, we only want to be informed when there is an overflow. We can disable the “LEVEL NORMAL” notification by sending: DISLEVEL NORMAL To later reinstate notification, we’d send: ENLEVEL NORMAL To change the password to “STARGATE” and disable acknowledgments, we could send: PASSSTARGATE ACKOFF To log out of the system and prevent further messages being sent by the controller: LOGOUT (the green LED goes out) Finally, note that all future logins will require the current password, as follows: LOGINSTARGATE Each command is sent as a separate message. After the ACKON command, the controller will acknowledge all subsequent commands; you should wait until you receive these before sending the next command. Although you don’t need acknowledgments turned on, it’s the only way to be certain that the controller has received and processed your commands. This is much more important during normal operation, when you’re far from the controller and can’t see what’s happening. The password and all user-programmed messages are stored in the micro’s EEPROM, so you only need to program the system once. The same goes for the output port state. If a power failure occurs, the last state will be automatically reinstated when power is restored. You can reprogram the system at any time simply by repeating the steps outlined above. When you redefine a message for any input or output, the old message is automatically overwritten. If you’d like to start from scratch, then all of the previously programmed messages can be deleted in one operation by erasing the microcontroller’s EEPROM. This is achieved by powering off and installing a jumper on JP1. When you power up again, all four red LEDs come on to indicate that erasure is complete. Note that this operation also wipes the password and all other parameters, including the “SMS sent” and “SMS received” counters. Finally, you can erase just the password by powering off and installing a jumper on JP2. At the next power on, the password will be erased. Be sure to remove JP2 when done, otherwise the PASS command will have no effect! Security While it’s not strictly necessary to program a password during setup and testing, we recommend that you do so before “going live”. A password is an effective way of preventing someone else taking control of the module without your knowledge. siliconchip.com.au Microcontroller Programming If you’re building this project from a kit, then the microcontroller (IC1) will have been programmed and you can ignore the following information. Alternatively, if you’ve sourced all the components separately, then you’ll need to program the microcontroller yourself. A 10-way header (CON5) has been included on the PC board for connection to an “in-system” type programmer. We described a suitable low-cost programmer in the October 2001 edition of SILICON CHIP. Kits for the programmer are currently available from Altronics (Cat. K-2885), on the web at www.altronics.com.au. Note that if you are using this particular programmer, the “Atmel AVR ISP” software described in the instructions is no longer available. A suitable alternative, named “PonyProg”, is available free from www. lancos.com. Set up PonyProg for the “AVR ISP (STK200/300)” parallel port interface as described in the included documentation for compatibility with the programmer. Some readers may also be familiar with the more recent “AVR ISP Serial Programmer”, described in the October 2002 edition. This newer programmer will do the same job but connects to your PC via a serial (rather than parallel) port. Kits for this programmer are available from Jaycar Electronics (Cat. KC-5340) – see www.jaycar.com.au As published, the AVR ISP Serial Programmer can successfully program the AT90S8515 microcontroller. However, to program many of the newer generation micros, including the ATMega8515, the code in the programmer’s on-board micro must first be updated. An update is available from the SILICON CHIP web-site. Once you have a suitable programmer, together with the necessary cables and Windows software to drive Once you’ve successfully logged in, the controller will only accept messages from your mobile phone number. Messages from all other numbers are simply ignored. An exception to this is the LOGIN command itself, which can siliconchip.com.au it, all you need to complete the job is a copy of the microcontroller program for the SMS Controller. This can be downloaded from our web site in a file named “SMS.ZIP”. “SMS.ZIP” contains the file “SMS. HEX”, which needs to be programmed into the micro’s program (FLASH) memory. Just follow the instructions provided with the programmer and software to complete the task. Fuse bits We’ve specified either AT90S8515-8 or ATMega8515-16 microcontrollers for this project. Although it has many improvements over its predecessor, the ATMega8515 is a pin-for-pin replacement for the AT90S8515. In fact, we’ve tested this project with both devices to ensure compatibility. The only additional requirement when using the ATMega8515 is to ensure that the fuse bits are correctly programmed (see Figs.10 & 11). The default fuse settings in the AT90S8515 are OK and should not be altered. The AT90S8515 & ATMega8515 Fig.10: if you’re programming your own ATMega8515 micro, you must also program the fuse bits. Here’s how they’re configured in AVR Prog, as used with the AVR ISP Serial Programmer. Once you’ve set all of the options exactly as shown, click on the “Write” button. micros are both stocked by Jaycar. The ATMega8515 is also available from Dontronics, on the web at www. dontronics.com Fig.11: the parallel port programmer (October 2001) uses PonyProg, which has an entirely different fuse configuration menu. Again, copy this example and hit the “Write” button. Don’t be tempted to experiment with different fuse settings unless you know exactly what you’re doing, as certain combinations can render the micro inoperable! be issued from any mobile number at any time, regardless of whether you’re already logged in or not. This allows you to regain control of the system using a second phone should your SC current phone be lost or stolen. Credits Thanks go to the gnokii team, who kindly published details of their work with the Nokia serial bus protocols. You’ll find their web site at: www. gnokii.org November 2004  79 CIRCUIT NOTEBOOK Interesting circuit ideas which we have checked but not built and tested. Contributions from readers are welcome and will be paid for at standard rates. Low coolant alarm for Falcon EF & EL Many vehicles have some sort of coolant high-temperature warning gauge or lamp. However, a water level switch is the best detector of sudden coolant loss, if catastrophic engine damage is to be avoided. Ford Falcon GLi EF and EL models have provision for installation of a low-coolant sensor in the surge tank. The Fairmont and Fairlane, which have the sensor as standard, operate an instrument panel warning light via the instrumentation computer. However, to retrofit this to other models, a simple electronic interface is required. The proprietary Ford magnetic level switch (Fig.2) measures 180Ω at correct (high) water level and 1380Ω at low water. These resistances are too high to operate typical automobile 85Ω relay coils, which draw about 150mA at 13.8V DC. To solve this problem, a simple transistor circuit can be used to One-second darkroom ticker An audible 1-second ticker is 80  Silicon Chip buffer the output from the level switch, as shown in Fig.1. D1 ensures that the circuit does not prematurely trigger with high battery voltages, while LED1 provides low water indication. The latter should be sufficiently bright under most daylight conditions. Q1 & Q2 can be any general-purpose small-signal switching transistors. Modern vehicles perform a selfcheck of the warning lights when the ignition is first switched on. Ideally, a fail-safe test of the water level circuit should also occur but in this case, the magnetic switch is always closed. That’s the reason for pushbutton “test” switch S2 – it turns Q1, Q2 and LED 1 on when pressed to show that the circuit is working. It’s not fail-safe but satisfactory if you remember to occasionally press the switch. All components except the LED and S2 can be built on a tag strip, which can then be mounted behind the clock panel. The panel facia is drilled to take a suitable rubber grommet or bezel to accommodate the LED. The circuit operates from 10-15V, which is taken from the fused side of the ignition circuit. The Ford sensor kit includes an “O” ring seal and locking nut. Before removing the proprietary electrical connector, thoroughly test the sensor and circuit by moving the float up and down. This is important, as Ford will not refund a damaged or modified unit! Obviously, the surge tank has to be drained below the threaded mounting point and a hole cut through this existing mount with a hole saw. Take care not to damage the threads. Retrieve all swarf to prevent pipe blockages. Refill with correct coolant and check for leaks under normal engine working conditions. Warning: header and surge tanks operate at pressures in excess of 100kpa (15psi) and up to 125°C using 33% Glycol coolant! Robert Gott, Toowoomba, Qld. ($30) easier to use in the darkroom than a visible clock. It enables the photographer to watch what he or she is doing when making test strips or the final print, rather than watching the clock. This device provides those ticks and is easily constructed. Begin by extracting the circuit board from a discarded quartz clock and disconnect the coil. The accompanying circuit shown at left can then be connected to the coil pads. The coil outputs are normally “high”, pulsing “low” for 30ms every two seconds in an alternate fashion. The two diodes (D1 & D2) perform an “OR” function, pulling the base of Q1 low briefly once every second. Each low pulse switches Q1 off and Q2 on, briefly sounding the piezo buzzer. And there’s your 1-second ticker! A. J. Lowe, Bardon, Qld. ($30) siliconchip.com.au CONTRIBUTE AND WIN! We pay good money for each of the “Circuit Notebook” contributions published in SILICON CHIP. But now there’s an even better reason to send in your circuit idea: each month, the best contribution published will win a superb Peak Atlas LCR Meter valued at $195.00. So don’t keep that brilliant circuit secret any more: sketch it out, write a brief description and send it to SILICON CHIP and you could be a winner! You can either email your idea to silchip<at>siliconchip.com. au or post is to PO Box 139, Collaroy, NSW 2097. Simpler PC power-up Here is an even simpler alternative to the auto power-up of ATX PCs mentioned in the June 2004 issue; it requires no parts at all! In ATX PCs, the motherboard controls the power supply by switching the “PS_ON” signal high (+5V) to enter standby mode or low (0V) for normal operation. The “PS_ON” signal appears on pin 14 of the motherboard’s power supply connector, as shown on the accompanying diagram. To prevent the power supply from entering standby mode, the “PS_ON” signal can be strapped permanently low. This can be achieved by cutting the track leading to pin 14 of the connector on the motherboard. A wire link can then be soldered between siliconchip.com.au pin 14 and pin 15 (“COM”) of the connector. If you don’t want to modify your motherboard, you may be able to remove the respective pin from the rear of the power supply connector housing and splice it into one of the “COM” return wires. Obviously, this will disable standby functionality completely, including front-panel power button control. This is great for auto power-up of servers on resumption of power after a UPS low-battery shutdown. I have my file server in the roof at home and this saves getting the ladder out after the all too frequent power failures. Before getting the tools out, it pays to check that your motherboard does not already have provision for automatic power-up when mains power is applied. This might be in the form of a jumper or settings in the BIOS, as detailed in “Mailbag” on page 4 of the September 2004 issue. Tarek Heiland, via e-mail. ($20) November 2004  81 Circuit Notebook – continued Micro timer with LED readout This circuit measures short duration events ranging from 10µs to 655ms, in 10µs increments. It has two logic-level (TTL) inputs that can be used to measure the high or low time of a pulse, or the time difference between two pulses. Applications include measuring the execution time of a microcontroller program, the time difference between output signals in a circuit, or the changeover time in switches & relays. It is particularly useful for measuring one-off events that can be difficult to catch on a scope. The circuit uses three 7-segment common-cathode LED displays for the readout. Two individual LEDs indicate whether the reading is in microseconds or milliseconds, with the software automatically selecting the correct range. The circuit requires +5V at approx. 25mA in standby and 100mA with all 18 segments turned on. In 82  Silicon Chip many cases, this can be sourced from the circuit under test. A PICAXE microcontroller measures the length of high-going pulses applied to pin 11. This pin is driven by the output of a 74LS86 XOR gate (IC2a). Two 74LS04 inverters (IC1a & IC1f) feed the XOR gate and act as buffers for the two inputs. Additionally, one of the inputs had a second inverter that can be switched in or out of the circuit with S2. Timing starts as soon as the signals applied to the two inputs differ, generating a high-going pulse on pin 11 of the micro. When both inputs again match, timing stops and the pulse length is displayed. Timing is also terminated if the pulse width exceeds the maximum measurement period (0.65s). When only one input is required, the signal should be applied to input 2 and input 1 grounded. LED3 indicates the state of the signal on the PICAXE input. Prior to the measurement, it should be off. If not, toggle switch S2 to invert the signal. The switch therefore allows the measurement of both high and low-going pulses. Referring now to the program listing, the PICAXE pulsin command is used to measure the pulse high time, which is stored in the variable word w5. This part of the program loops until a value greater than zero is detected. Measurement is in 10µs steps, so when the number 1 is returned, it corresponds to a time of 10µs. Be aware that a 43µs pulse will be read as a 4 and displayed as 40µs. This loss of precision only occurs in measurements under 1ms. Measurements over 1ms are correct. When a pulse is detected, w5 is tested to see if it is greater than 99 (990µs). If not, simple division splits the first 2 digits into b1 and b2. The “µs” indicator (LED2) is then turned on by setting pin 13 (portc 2) low. If the value is greater than 99, the software jumps to the “ms:” section. First, the “ms” indicator (LED1) is siliconchip.com.au turned on by setting pin 13 (portc 2) high. Next, a check is made to see if w5 is less than 99ms. If so, there must be a decimal place, so the decimal point is turned on (portc 3). Division of the returned value occurs, with the results in b1, b2 and b3. If w5 is greater that 99ms, then the “high_ms:” routine is executed. The value in w5 is divided by 1000, placed in b0, and the first two digits divided into b1 and b2. To get the third digit, b0 is multiplied by 1000 and placed in w4. Again, the results are returned in variables b1-b3. Finally, the results from the “decode:”, “ms:” or “high_ms:” sections are displayed on the readout by the “display:” routine. This part of the program loops back on itself, so that the last measurement is held on the display until the reset switch (S1) is pressed. Seven of the PICAXE-18X’s dedicated output pins (out1 - out7) are used to drive the segments in each of the displays via 150Ω currentlimiting resistors. The value for each digit is stored in the variables b1, b2 & b3, as described above. Using the lookup command, the program converts these values into a binary pattern needed to illuminate the correct segments. The result is then written to the output port using the pins command. As the anode pins of all three displays share the same seven output lines, a multiplexing technique is used to sequentially enable each display for 3-5ms at a time. This is achieved in the circuit by turning on transistors Q1, Q2 & Q3 in turn, grounding the common-cathode pins of the displays. Three portc output pins drive the transistors via 1.8kΩ biasing resistors. A secondary use for this circuit and software is as the basis for any project where 7-segment readouts need to be driven by a PICAXE. This is achieved simply by omitting the input circuit and indicator LEDs. Also, delete the program lines prior to the “display:” routine. In its present form, the “display:” routine will drive three 7-segment displays, though a fourth is easily added. Brett Cupitt Ashfield, NSW. ($60) siliconchip.com.au 'Pulse length measurement and display for PICAXE-28X 'Registers,b10,b11 (w5) = pulse length 'b5 = 7 segment display, segment config data 'b0 = temporary/working register 'b1-b4 = digits to be displayed; b1=MSB, b3=LSB init: let w5=0 'clear w5 value measure: pulsin 0,1,w5 if w5>0 then decode: goto measure: 'pulse length measure routine 'read pulse length on input 0 into w5 'if we have a reading, process it 'loop if no value decode: if w5>99 then ms: low portc 2 let b1=w5/10 let b2=w5//10 let b3=0 goto display: 'are we measuring us or ms 'if its a value in ms, go to ms section 'OK, its a value in us, turn us LED on 'MSB '2nd digit 'LSB 'now display it ms: high portc 2 if w5>9999 then high_ms high portc 3 let b0=w5/100 let b1=b0/10 let b2=b0//10 let b3=w5//100/10 goto display: 'turn ms LED on 'is it a big or little number? 'decimal point on 'get the 1st 2 digits 'MSB '2nd 'LSB 'now display it high_ms: let b0=w5/1000 let b1=b0/10 let b2=b0//10 let w4=b0*1000 let w4=w5-w4 let b3=w4/100 'get 1st 2 digits 'get MSB 'get 2nd digit 'calculate the 1000’s 'take these away from the total 'the hundreds are left, get the MSB display: 'start of data display routine lookup b3,($7e,$0C,$B6,$9E,$CC,$DA,$FA,$0E,$FE,$DE),b5 low portc 6 'turn off MSB let pins=b5 'output 7 segment display sequence high portc 4 'turn on LSB pause 6 'hold for 6ms lookup b2,($7e,$0C,$B6,$9E,$CC,$DA,$FA,$0E,$FE,$DE),b5 low portc 4 'clear LSB let pins=b5 'output 7 segment display sequence high portc 5 'turn on 2nd digit pause 4 'hold for 4ms lookup b1,($7e,$0C,$B6,$9E,$CC,$DA,$FA,$0E,$FE,$DE),b5 low portc 5 'turn off 2nd digit if b1=0 then display: 'blank leading zeroes let pins=b5 'output 7 segment display sequence high portc 6 'turn on MSB pause 4 'hold for 4ms goto display: 'cycle November 2004  83 Circuit Notebook – continued Jeff M is this monegal winner onth’s Peak At of the las L Meter CR 84  Silicon Chip siliconchip.com.au Water pump monitor ' Water Pump Controller v1.00 ' PICAXE-08 This circuit is designed to stop a fresh water pump from running too long. When you live on the land, your water supply is stored in tanks and you tend to be more vigilant about water use. If, for example, a pipe ruptures or a tap is left open, loss of pressure in the line will cause the pump to start. If the owner does not know this or is away, then the pump could empty a full tank within a short time. The project was conceived when a water pipe burst while I was away for the weekend. Luckily, a neighbour noticed the water spout and shut the pump off. If the tank had emptied that would have been bad enough but the cost of a burnt-out pump would have been much worse. Another use is as a timer for watering the garden. Pick a time and turn on the tap. This unit will shut off the pump and sound an alarm at the end of the selected time. Perhaps you have teenagers that like to take long showers. Set the time to 10 minutes and watch them complain! Five different times are available and these can be altered to suit your needs by editing the microcontroller program. To reset the pump after a time out, simply press the reset button for two seconds. The circuit works by detecting the vibrations from the pump while it is running. When the pump starts, a timer is started and after the set time has elapsed the pump will be shut off and an alarm sounded. If the pump you have is quite powerful, pressure in the line can build up high enough to stop the pump. If a tap is still open, the pump will start again when the pressure drops. The software takes all this into consideration and is not fooled by the pump switching on and off. The pump must be off for more than 20 seconds for the program to reset the timer and think that the tap has been closed. A PICAXE-08 microcontroller runs the whole show. It knows the pump is running because a piezo sensor is physically mounted on the pump. Motor vibrations excite the piezo sensor, generating a small AC voltage across its terminals. This signal is amplified continued next page start: symbol cntr = b2 symbol time = w0 symbol pump = 2 symbol bell = 0 symbol reset = pin3 siliconchip.com.au one: time = 900 return begin: low pump cntr = 0 main_lp: if pin4 = 0 then run goto main_lp run: pause 2000 if pin4 = 1 then main_lp gosub read_time 'make sure pump is enabled 'clear the “pump off time” counter 'if pin 4 goes low the pump is running 'debounce the pump for 2 seconds 'if pin4 = 1 then false start 'read the “time set switch” time_loop: time = time - 1 if time = 0 then alarm if pin4 = 1 then is_pump_stopped 'pump off for > 20 secs? cntr = 0 goto all_ok is_pump_stopped: pause 100 if pin4 = 0 then all_ok cntr = cntr + 1 if cntr = 20 then begin 'pump debounce delay 'if pump still on the continue 'count seconds pump is off 'if > 20 secs put system in standby all_ok: pause 1000 goto time_loop alarm: high pump loop: pulsout bell,50 pause 300 pulsout bell,50 if reset = 0 then begin pause 3000 goto loop 'disable the pump 'sound the buzzer 'sound the buzzer again 'if reset switch pressed, reset system 'This routine looks at the select time switch (S1) 'and loads required value into “time” variable read_time: readadc 1,b0 if b0 > 30 then four time = 5400 return four: if b0 > 55 then three time = 2700 return three: if b0 > 83 then two time = 1800 return two: if b0 > 110 then one time = 1200 return November 2004  85 Circuit Notebook – continued Reducing the effective mains voltage Would you like to use a particular power transformer in an amplifier or some other project you’re building but its secondary voltage is just a little too high? Or perhaps you have an imported piece of equipment with a power transformer rated for a mains voltage of 220V, so it gets too hot and bothered running from 240V? It’s easy to solve these and similar problems by using a standard off-the-shelf low voltage transformer as a DIY autotransformer, to reduce the effective mains voltage fed to your equipment. The idea is to connect some or all of the secondary winding of the extra transformer in series with the mains voltage fed to your equipment, with its polarity chosen so that its voltage subtracts from the 240V input (see circuit A). Here a standard transformer with a 12V-0-12V secondary winding is connected with the full secondary in series with the active output lead, so the effective output voltage becomes 240V - 24V, or 216V. This exact arrangement would be fine for any application where you need to reduce the mains voltage for equipment by about 10%, to make its power transformer run cooler or to bring its secondary voltage down so your power supply electros can be run within their ratings. Of course, if you don’t need to reduce the mains voltage by a full 10%, you could use only half the secondary winding connected in series with the active output lead. This will give an output voltage of 240V - 12V, or 228V (a reduction of 5%). Or you could use a transformer with a multi-tapped secondary voltage, which would allow you to reduce the output voltage in steps of 1.5V or 3V. When you’re choosing the transformer for this kind of use, make sure that its secondary winding is rated to handle the full-load primary current of the main power transformer in the equipment it’s to be used with. So if your amplifier has a 300VA power transformer, for example, its full-load primary current will be around 1.25A (300/240V). In this case, you’d pick a mains-reduction transformer with a secondary winding rated to handle 1.5A or 2A and with a voltage equal (or close) to the mains voltage reduction you want. Can you use the same kind of transformer to step up the effective mains voltage by 10% or so? Yes, simply by connecting its secondary winding (or a part of it) in series with the active mains lead with its polarity reversed, so the secondary voltage adds to the output instead of subtracting. This is illustrated in circuit B, where the same transformer is connected with half its secondary in series, to add 12V to the mains input and deliver an output of 252V. Note that because both of these circuit configurations use the additional transformer as an autotransformer, they do not provide any isolation. For safety reasons, fit the transformer in a sturdy metal box, and connect both the box and the transformer frame to mains earth. SILICON CHIP. 86  Silicon Chip Water pump monitor: continued from page 85 by op amp IC2a, which is set for a gain of about 85. From here, the signal is rectified by a diode pump circuit and then compared with the voltage on the wiper of VR1 by op amp IC2b. When the voltage on pin 5 exceeds that on pin 6, the output of the op amp swings high, turning on Q3. This turns on the LED and pulls pin 3 of the micro (IC1) to a logic low level via D4. Next, the micro reads the voltage on pin 6 as selected by S1. As this pin is an ADC (analog-to-digital converter) input, the voltage read will vary according to the position of the switch. The result is used by the program to select one of five times from a look-up table stored in memory. The pump “run” timer now starts and if the signal on pin 3 remains low (pump on) for longer than the selected time period, the micro drives pin 7 high to switch on Q2, sounding the alarm. More importantly, it also drives pin 5 high, switching on Q1 and energising the relay, which in turn opens the normally-closed contacts to disconnect the pump motor. To reset the pump, just press the reset button (S2). The pump will now start again because there will be no pressure in the line. Once pressure has built up again the pump will stop, assuming you have turned off the offending tap or fixed the fault with the lines. The five selectable times are determined by the number stored in the “time” variable. Each unit equals one second. For example, to set a time of 30 minutes, the number 1800 would be used. As it stands, the program has been set for 90, 45, 30, 20 and 15 minutes. When mounting the piezo sensor, make sure that it is physically touching the pump. Most pumps have removable end plates. The disc can be inserted between the end plate and the pump body. Any single-plate piezo transducer can be used for the job. Many piezo transducers come with a plastic surround. Remove the disc by prising it out of the surround before mounting. Oatley Electronics sells discs that are ideal for this application. Jeff Monegal, North Maclean, Qld. siliconchip.com.au PRODUCT SHOWCASE New look “ergonomic” digital multimeters Tenma have released a new range of ergonomic and modern-looking digital multimeters. The range includes the 72-7720 (pictured), a full function multimeter offering a variety of ranges for every service application and meeting 1000V CAT II standards. A rugged overmoulded housing stands up to the daily rigors of field service use and large backlit LCD display is easily read from several feet away. Measurements include AC/DC voltage, AC/DC current, resistance and capacitance. The 3-1/2 digit, 1999- count display features 22mm digits for easy at-aglance reading. Additional features include continuity buzzer, data hold, full icon display, sleep mode and low battery display. Standard test leads are included, along with separate short leads for accurate capacitance checking, a 9V battery and owners manual. The multimeter is distributed by Farnell InOne (order code 743-0582). Contact: Farnell InOne PMB 6, Chester Hill NSW 2162 Tel: 1300 361 005 (NZ 0800 90 80 80) Website: www.farnellinone.com World’s first large-screen OLED display Seiko Epson Corporation has used its original inkjet printing technology to successfully develop the world’s first large-screen (40-inch) full-color organic light-emitting diode (OLED) display prototype. Self-luminescent OLED displays, which offer outstanding viewing characteristics, including high contrast, wide viewing angle and fast response times, are widely seen as the leading candidate for the next generation of thin, lightweight displays. One of the major obstacles to their realisation, however, has been the difficulty of forming organic layers on large-sized TFT (thin film transistor) siliconchip.com.au substrates. Epson has been actively working to develop and commercialise next-generation OLED displays. The company, a leader in inkjet printers, has developed an original inkjet process for depositing organic layers on large-size TFT substrates. By establishing an OLED display manufacturing system and process that can handle oversized substrates, Epson has beaten a path to large-size OLED displays, as well as to lower cost small and medium-sized panels cut from larger TFT substrates. Epson believes that the characteristics of OLED displays make them the ideal device for entertainment applications, whether in equipment for the road or living room. The company is gearing up towards commerial production in 2007. Contact: Seiko Epson Corp Locked Bag 2238 North Ryde BC1670 Tel: (02) 8899 3666 Fax:(02) 8899 3777 Website: www.epson.co.jp Hard-to-find wireless LAN adapters/pigtails Microgram has a range of normally-hard-to-get adapters and pigtails for wireless LAN applications. Included are: Reverse SMA to type N female adapter (Cat No. 15154-14, rrp $27.00). Connects the majority of access points directly to low-loss (LMR-400) antenna cable I.Pex MHF to N female pigtail (Cat No. 9191-14; rrp $35.00) These connects a mini PCI 802.11a/g card to an N female connector. Consists of an I.PEX MHF series plug, also known as U.FL (Hirose), to N female bulkhead mount. Male N to reverse F MMCX pigtail (Cat No. 9219-14; rrp $30.00) – connects 200mw PCMCIA wLAN cards to low loss (LMR-400) antenna cable. Wireless RF adapter set (Cat No. 9211-14 RF; rrp $239). Need an RF adapter? Make the one you need. There are two by 16 different connectors that can be assembled in any combination. Contact: Microgram Computers 1/14 Bon Mace Cl, Berkeley Vale 2261 Tel: (02) 4389 8444 Fax: (02) 4389 8388 Website: www.microgram.com.au AUDIO MODULES broadcast quality Manufactured in Australia Harbuch Electronics Pty Ltd 9/40 Leighton Pl. HORNSBY 2077 Ph (02) 9476-5854 Fx (02) 9476-3231 November 2004  87 Preamp kit, sinewave inverter from DSE Dick Smith Electronics have submitted their version of the Balanced Mic Preamp with 3-band equaliser (August 04 SILICON CHIP). The kit is quite different in appearance from that published – it’s housed in a black instrument case, for example – but is electrically identical. The case is silk-screened and prepunched front and back, making assembly very simple and giving a very professional result. The kit (K7219) retails for $59.87 The other item of note is a 300W True Sinewave Inverter (M5113) which, as its name suggests, supplies 230V AC, 50Hz from a 12V DC source. Many cheap inverters provide chopped or modified DC output – and many electronic devices do not like this one little bit! The output of this inverter however is a true sinewave (very close to that of a normal mains supply). It will therefore operate most 240V equipment (within its 300W output limit). It has two standard 240V outlets on the front panel. The high-efficiency inverter has overload protection and low battery warning. It retails for $294.00 and is available from all DSE stores, PowerHouse stores and via on-line and mail orders. Contact: Dick Smith Electronics (all stores) Reply Paid 500, PO Box 500, Regents Park DC NSW 2143. Tel: 1300 366 644 Fax: (02) 9642 9155 Website: www.dse.com.au 88  Silicon Chip Special offer on Altronics pro-quality cans Altronics distributors were so happy with the quality and performance of their new CD-90 studio quality headphones they sent us a pair to try out . . . and they do live up to their claims. As well as being exceptional performers, suitable for use as studio monitors or high fidelity music appreciation, these lightweight ’phones are extremely comfortable, with earpieces that can swivel through both axes. With Neodymium magnets in the 50mm drivers, they have a frequency response of 100Hz to 30kHz with a rated SPL of 100dB. Nominal impedance is 32W. For November and Dec e m b e r, A l t r o n i c s stores and mail/online orders are offering these headphones (Cat C9014) at a special price for SILICON CHIP readers: $90.00 instead of the usual $99.00. Don’t forget to tell them you saw the ’phones in SILICON CHIP! Contact: Altronics Distributors Box 8350, Perth Business Centre 6849 Tel: 1300 797 007 Fax: (08) 9428 2187 Website: www.altronics.com.au European-styled LCD TVs from Baumann Meyer It’s not a name you’d instantly recognise but for the past few years Baumann Meyer has been building a reputation as a supplier of stylish and technologically advanced LCD televisions to the Australian market. The company has now released what is arguably the most stylish and distinctively European looking 66cm (26inch) widescreen (1280 x 768 pixels) LCD television - the DT-2600. In airbrushed aluminium surrounds, the new Baumann Meyer DT-2600 LCD television features a 96 channel multizone analog tuner, plus matching SD set top box to receive the best in both analog and digital transmissions. The DT-2600 has a 500:1 contrast ratio and enhanced brightness (450cd) that translates into picture detail and colour brilliance that makes for the most realistic and natural picture colour available. The built-in 12W stereo amplifier can be set for stereo, pseudo stereo and surround via its 2-channel output. Video features include, Teletext, Digital Action Freeze, Picture-in-Picture mode, and PC compatibility. For connection to the latest in a/v equipment, the DT-2600 offers RGB via SCART, Component, S-Video, Composite video/audio and RF. With its centre of gravity strategically centred to offer a very stable footprint, it’s suitable for coffee table and side table placement as well as wall mounted. Available at selected retailers, the DT-2600 has a recommended retail price of $3999 (includes digital Set Top Box). The DT-2600 is just one in the range of Baumann Meyer’s lifestyle LCD TVs. Other models include the 80cm (32 inch) widescreen at $4999 for release in October, the 51cm (20 inch) WTP20B2 at $1850, and the 38cm (15 inch) WTP-15B2 at $950. Contact: Baumann Meyer PO Box 594, Balgowlah NSW 2093 Tel: 1300 656 369 Fax: (02) 9977 6007 Website: www.baumannmeyer.com.au siliconchip.com.au SILICON CHIP WebLINK How many times have you wanted to access a company’s website but cannot remember their site name? Here's an exciting new concept from SILICON CHIP: you can access any of these organisations instantly by going to the SILICON CHIP website (siliconchip.com.au), clicking on WebLINK and then on the website graphic of the company you’re looking for. It’s that simple. No longer do you have to wade through search engines or look through pages of indexes – just point’n’click and the site you want will open! Your company or business can be a part of SILICON CHIP’s WebLINK . For one low rate you receive a printed entry each month on the SILICON CHIP WebLINK page with your home page graphic, company name, phone, fax and site details plus up to 50 words of description– and this is repeated on the WebLINK page on the SILICON CHIP website with the link of your choice active. Get those extra hits on your site from the right people in the electronics industry – the people who make decisions to buy your products. For information, call BENEDICTUS SMITH Pty Ltd today on (02) 9211 9792 JED designs and manufactures a range of single board computers (based on Wilke Tiger and Atmel AVR), as well as LCD displays and analog and digital I/O for PCs and controllers. JED also makes a PC PROM programmer and RS232/RS485 converters. Jed Microprocessors Pty Ltd We endeavour to provide a range of technical books of interest to the Radio Amateur as well as electronics enthusiasts, at competitive prices. Special discounts are offered to WIA members. We are the only bookshop of this type in Australia. Tel:(02) 9689 2417 Fax: (02) 9633 1525 Our website is updated daily, with over 5,500 products available through our secure online ordering facility. Features include semiconductor data sheets, media releases, software downloads, and much more. For everything in radio control for aircraft, model boats and planes, etc. We also carry an extensive range of model flight control modules including GPS, altitude and speed, interfaces, autopilot and groundstation controllers. More info on our website! JAYCAR JAYCAR ELECTRONICS ELECTRONICS Tel: Tel: 1800 1800 022 022 888 888 WebLINK: www.jaycar.com.au WebLINK: www.jaycar.com.au TeleLink Communications Wireless Institute of Australia (VK2) Tel: (03) 9762 3588 Fax: (03) 9762 5499 WebLINK: jedmicro.com.au We specialise in providing a range of Low Power Radio solutions for OEM’s to incorporate in their wireless technology based products. The innovative range includes products from MK Consultants, the world-renowned specialist manufacturer. Tel:(07) 4934 0413 Fax: (07) 4934 0311 WebLINK: telelink.com.au WebLINK: wiansw.org.au/bookshop/ Silvertone Silvertone Electronics Electronics Tel:(07) 4639 1100 Tel/Fax: (02)Fax: 9533(07)4639 3517 1275 WebLINK: www.silvertone.com.au WebLINK: silvertone.com.au 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°. Av-COMM Pty Ltd Tel:(02) 9939 4377 Fax: (02) 9939 4376 Tel:(02) WebLINK: avcomm.com.au WebLINK: avcomm.com.au A 100% Australian owned company supplying frequency control products to the highest international standards: filters, DIL’s, voltage, temperature compensated and oven controlled oscillators, monolithic and discrete filters and ceramic filters and resonators. Hy-Q International Pty Ltd Tel:(03) 9562-8222 Fax: (03) 9562 9009 WebLINK: www.hy-q.com.au . Elexol offers SILICON CHIP readers 10% discount on I/O USB add-on boards Last month we introduced SILICON CHIP readers to the new range of USB modules from Elexol. The Elexol USBIO24 V3 is the second generation of a low-cost integrated module for the input and/ or output of digital signals from a computer system by connection to the USB port. The USB port also supplies power to the module. siliconchip.com.au Elexol now also have a range of add-on boards for the I/O module, significantly extending an already very versatile system. Included in the range are an opto-isolated input board, aconnector/LED board, a switch/push button board and a 50-pin IDC connector board. All can be viewed on the Elexol website, www. elexol. com.au/IO_Modules, along with their specifications. Even more importantly, if you order any of these boards via their online store and quote the code SIL1104, Elexol will give you 10% off for the month of November. While you’re on line, check out Elexol’s other goodies! Contact: Elexol Pty Ltd PO Box 5972, Bundall Qld 4217 Tel: (07) 5574 3988 Fax: (07) 5574 3833 Website: www.elexol.com.au November 2004  89 Here’s how to add infrared remote control to all your PICAXE-08M projects! PICAXE infrared remote control By Clive Seager I N THE SEPTEMBER 2004 issue, we showed you how to assemble “Rudolph the Red-Nosed Reindeer”. Rudolph is a simple Christmas decoration with flashing LEDs that can play a variety of tunes, including mobile phone ring tones. As promised, this month we assemble the infrared remote transmitter and add the receiver components to Rudolph’s PC board. Before we describe how to assemble the various pieces, let’s first take a look at the basics of infrared transmission on the new PICAXE-08M. Infrared remote control The PICAXE-08M includes two commands for sending and receiving data over an infrared link. The infraout command sends data on pin 7, whereas the infrain2 command receives data on pin 3. Data is transferred using a simple modulation technique based on the well-documented Sony Infrared Remote Control System (SIRCS) protocol. The SIRCS protocol uses a 38kHz modulated infrared signal consisting of a start bit (2.4ms) followed by 12 data bits (7 data bits and 5 device ID bits). Logic level “1” is transmitted as a 1.2 ms pulse, logic ‘0’ as a 0.6ms pulse. Each bit is separated by a 0.6ms gap (see Fig.1). When used within Sony production devices, the 5 device ID bits represent the type of equipment (1 = TV, 2 = video, 26 = DVD, etc). The 7 data bits represent different commands (1 = channel 2, 2 = channel 3, 16 = channel up, 20 = mute, etc). Within this PICAXE project the Sony-allocated commands are not relevant, but a full list is provided in the PICAXE manual for those interested in controlling their own Sony hardware! Fig.1: basics of the SIRCS protocol, showing the composition of each serial transmission. A logic “1” is represented by a 1.2ms burst of the 38kHz carrier, whereas a logic “0” is represented by a shorter 0.6ms burst. Each bit is separated by a gap of 0.6ms. 90  Silicon Chip Sending data To transmit infrared data, the PICAXE command is: infraout device,data For example, to send the Sony command “TV - mute”, the command would be infraout 1,20. Note that device should always be 1 when used in PICAXE projects and data can only be between 0 and 127, as the SIRCS protocol only specifies 7-bit capability. The full program for the transmitter is shown in Fig.6. As infrared signals are easily corrupted, the data is actually sent 10 times to increase reliability. This matches commercial remote controls that tend to transmit the data at 45ms intervals whilst the button is held down. Note that the program uses codes “1”, “2” and “3” for the three switches, but you can edit these to any number between 0 and 127. This would be useful when you want to control multiple units in the same room, using different data commands for each unit. Building the transmitter As hinted at in September, the various tunes played by Rudolph can be triggered remotely using an infrared transmitter. This simple project uses a PICAXE-08M micro, three pushbutton switches and an infrared LED to make a complete hand-held remote, the circuit for which appears in Fig.2. A second visible LED is included for user feedback. siliconchip.com.au Parts List 1 infrared PC board 3 miniature pushbutton switches (S1 - S3) 1 battery clip 1 3 x AA battery holder 1 8-pin IC socket Semiconductors 1 PICAXE-08M (IC1) 1 Vishay TSOP4838 infrared receiver IC 1 5mm yellow LED (LED) 1 5mm infrared LED (IRLED) Capacitors 1 4.7µF 16V PC electrolytic Fig.2: circuit diagram for the simple infrared transmitter. As no serial link socket is provided, the PICAXE chip must first be plugged into the “Rudolph” PC board (described in September 2004) for programming. Resistors (0.25W 5%) 3 10kΩ 2 330Ω Also required (not in the kit) Rudolph kit (part no. AXE107S) PICAXE Programming Editor software (v4.1.0 or later) PICAXE download cable (part no. AXE026) 3 x AA alkaline cells Obtaining kits & software The design copyright for this project is owned by Revolution Education Ltd. Complete kits (Part No. AXE108S) and/or the Vishay infrared receiver (Part No. LED020) for this project are available from authorised PICAXE distributors – see www.microzed.com.au or phone Microzed on (02) 6772 2777. The PICAXE Programming Editor software can be downloaded free of charge from www.picaxe. co.uk or ordered on CD (part no. BAS805). Fig.3: the overlay diagram for the infrared remote transmitter. Install the wire link (under IC1) first, then all the other parts, making sure that the IC socket is around the right way. Assembly is very straightforward and should only take a few minutes. Begin by installing a wire link in the position indicated by a dotted line on the overlay diagram (Fig.3). An off-cut resistor leg is ideal for the job. Note that as an IC socket will be mounted over the link, it must be lying flat on the PC board before soldering. Install all of the resistors, switches and IC socket next, making sure that you have the notched (pin 1) end of the socket around the right way. Install the two LEDs next, noting that the infrared LED (IRLED1) leads must be bent at 90 degrees so that it points away from the PC board (see siliconchip.com.au Fig.4: transmission range can be increased by adding an external transistor circuit to drive the infrared LED. photo). Make sure that you have the flat (cathode) sides of the LEDs oriented correctly. The infrared LED may be supplied in either a “black” or “water clear” epoxy package. Finally, solder the battery leads to the positions indicated after threading through the adjacent hole. Note that the board runs from a 4.5V (3 x AA) battery pack – do not connect a 9V PP3 battery! To reduce overall size, a serial link socket is not provided on the transmitter PC board. Therefore, the PICAXE08M chip must be programmed on the main Rudolph PC board and then transferred to the transmitter board. After assembly and programming, November 2004  91 pin and the LED, as shown in Fig.4. Fig.5: any PICAXE-08M can receive infrared remote control signals with the addition of just a few components, as shown here. you can check transmitter operation by looking at the infrared LED “end-on” through a webcam or digital camera (such as a mobile phone camera). Although the LED is not visible to the naked eye, these camera are sensitive to infrared light and so the infrared LED will display a faint glow on the camera screen whilst operating. Extending transmitter range A 330Ω resistor is used in series with the infrared LED to limit current flow from the PICAXE port pin to an acceptable level. This gives a transmission range of about 4-5 metres, which should be enough for most users. However, infrared LEDs can typically be driven with a much higher current, thus extending the potential transmission range. If you need the maximum possible range, then a transistor driver circuit can be added between the PICAXE infrared output Fig.6: Transmitter Program Listing ' Wait until switch press main: if pin1 = 1 then tx_1 if pin2 = 1 then tx_2 if pin3 = 1 then tx_3 goto main Legs Versus Pins tx_1: let b1 = 1 goto tx_ir 'Code 1 tx_2: let b1 = 2 goto tx_ir 'Code 2 tx_3: let b1 = 3 goto tx_ir 'Code 3 In PICAXE BASIC, “pin” refers to a logical input or output port number, not a physical pin. Conversley, physical pins are referred to in the PICAXE documentation as “legs”. Confused? We’re not surprised. When describing a PICAXE circuit, SILICON CHIP will continue to refer to physical pins as “pins”, just as we do for all our projects. We’ll leave the legs for the organic world! (Editor.) ' Transmit code 10 times for increased reliability tx_ir: high 4 'visual LED on for user feedback for b2 = 1 to 10 'send infrared code 10 times infraout 1,b1 pause 45 next b2 low 4 'LED off goto main 92  Silicon Chip Receiving data The infrared receiver portion of the “Rudolph” circuit from last month is reproduced in Fig.5. Any PICAXE08M project can receive infrared remote control signals with the additional of these four components. A Vishay TSOP4838 infrared receiver IC demodulates the 38kHz carrier wave to give a logic output. It also contains filters to suppress noise signals from devices such as fluorescent lights. The block diagram of the receiver is shown in Fig.8. To receive infrared data, the PICAXE command is simply: infrain2 This command waits for a valid input signal and then stores the data in a variable named “infra”. This variable can then be used to play different tunes, as shown in the full receiver program in Fig.7. As the PICAXE-08M uses the standard SIRCS protocol, the receiver will also work with commercial “universal” style infrared remote transmitters. These are widely sold as “one-for-all” replacements for use with home audio and video equipment. All you need to do is program them with one of the Sony-compatible equipment codes from the supplied list of manufacturers codes. Rudolph upgrade Only two parts remain to be added to the Rudolph PC board. The receiver IC is soldered into the “IR” position, with the leads bent over so that it lies flat on the board. A 4.7µF capacitor is also added to filter the supply, noting that the positive lead goes in as indicated by the “+” marking on the overlay diagram. The 330Ω and 4.7kΩ resistors should already be installed on the board, as they were part of the original assembly. Finally, reprogram Rudolph with the BASIC code listed in Fig.7, which adds the necessary infrared remote control functions. That done, you should be able to choose between three tunes using the buttons on your remote control board! Summary With a minimum of external components and the new infraout and infrain2 commands, you can add remote control capability to all of your siliconchip.com.au Fig.7: Receiver Program Listing ' ***** main loop ***** main: infrain2 'debug infra 'wait until infrared signal 'optional display on screen for testing Silicon Chip Binders REAL VALUE AT $12.95 PLUS P & ' ***** play tune ***** 'play tune depending on light level if infra = 3 then play_xmas if infra = 2 then play_rudolf if infra = 1 then play_jingle goto main play_jingle: P 'internal tune Jingle Bells play 1,3 goto main play_silent: play 2,3 goto main 'internal tune Silent Night play_rudolf: 'internal tune Rudolf The Red Nosed 'Reindeer play 3,3 goto main play_xmas: These binders will protect your copies of S ILICON CHIP. They feature heavy-board covers & are made from a dis­ tinctive 2-tone green vinyl. They hold up to 14 issues & will look great on your bookshelf. H 80mm internal width 'external ring tone tune 'We Wish You a Merry Xmas tune 3, 4,($22,$27,$67,$69,$67,$66,$24,$24,$24,$29,$69,$6B,$69,$67, $26,$22,$22,$2B,$6B,$40,$6B,$69,$27,$24,$22,$24,$29,$26,$E7,$22, $27,$67,$69,$67,$66,$24,$24,$24,$29,$69,$6B,$69,$67,$26,$22,$22, $2B,$6B,$40,$6B,$69,$27,$24,$22,$24,$29,$26,$A7,$22,$27,$27,$27, $E6,$26,$27,$26,$24,$E2,$29,$2B,$69,$69,$67,$67,$02,$22,$22,$24, $29,$26,$E7) goto main H SILICON CHIP logo printed in gold-coloured lettering on spine & cover H Buy five and get them postage free! Price: $A12.95 plus $A7 p&p per order. Available only in Aust. Silicon Chip Publications PO Box 139 Collaroy Beach 2097 Or fax (02) 9979 6503; or ring (02) 9979 5644 & quote your credit card number. Use this handy form Enclosed is my cheque/money order for $________ or please debit my  Bankcard  Visa    Mastercard Card No: _________________________________ Fig.8: this diagram reveals the basic functional blocks within the TSOP4838 infrared receiver. As well as the actual PIN (photo) diode, it includes amplifier, discrimination and demodulation circuits to reconstruct the original digital data, which appears on the “OUT” pin. Card Expiry Date ____/____ Signature ________________________ Name ____________________________ Address__________________________ PICAXE-08M projects. “Rudolph the Red-Nosed Reindeer” demonstrates siliconchip.com.au how it all works, and might even be a party favourite come Christmas! SC __________________ P/code_______ November 2004  93 Is this one of Stan’s wind-ups? Emergency power, when all else fails... B ack in the 20th century, it used to be said that you really knew you were a parent when battery costs for your kid’s toys exceeded monthly power bills. Fortunately, recent spectacular improvements in rechargeable technology now offer cost-effective secondary batteries and chargers – and at keen prices. NiMH “AA” cell energy capacities have near tripled from 750mAh to well over 2000mAh since the year 2000. It’s assumed you’ll have a nearby mains outlet for recharging – but many occasions arise (commuting in a peakhour train maybe) when you’re away from such facilities but with hi tech toys crying for a top up. Such an occasion arose recently, when bad weather meant a mate on a weekend walkabout, hunting in a nearby but isolated NZ mountain region became hut-bound for nearly a week – trapped by a flooded river. Although warm and dry indoors, the batteries in his mobile phone, radio and torch all progressively ran flat. Even his digital camera, intended for the 12-pointer deer he’d hoped to shoot, gave up! Perhaps a solar panel would have helped, although the scudding winter rain clouds, which caused the flood in the first place, rather hinted otherwise. In despair at his “Joule less” plight, he even took to the old trick of warming batteries in the oven and chewing their outer casings to persuade a few more electrons to flow… At least he had an ultra bright white LED torch! Let’s face it – these efficient lighting devices have been one of the most benevolent developments in 94  Silicon Chip by Stan Swan Above: the Benex Dynamo Torch, from Jaycar, which forms the basis of our emergency power plant. Below, winding the handle produces the power to charge the batteries. siliconchip.com.au The opened-up torch, showing where we “tapped in” to the rectified dynamo supply (blue arrows). It’s not difficult to do and the full functions of the torch are retained. Of course any neat output socket could be used but simple red and black banana types were found most versatile – space inside the torch just allows for these – and likely to be the most useful with cold hands or broken connectors. The torch’s existing lighting circuitry remains quite unchanged, so naturally it still operates as a very bright and ergonomic LED torch. Performance? decades. But even they typically only offer 80 hours on “lite” mode – perhaps a week of evening use if half charged. Yes, all very inconvenient – but fortunately just as Search and Rescue were being briefed the lost hunter reappeared. Improvise . . . or starve! Back at civilisation, the challenge was put to me: “Fix me up a reliable charger, or no venison next trip”. A past SILICON CHIP article on modified disk drive generators sprang to mind but their output looked limited to LED lighting only. Additionally, bush tramping demands near-bullet-proof devices, otherwise rain and mud may rule over fine engineering. Marine emergencies further throw their own brand of cruelty and inconvenience… Short of carrying in a generator, PV panel and SLA gel cell, rigging a thermocouple to the fireplace or poking a wind turbine above the bush line, just what other ready approaches exist to generate a few crucial watts? Digital smoke signals? output of a good half amp. Impressive, although perhaps rather optimistic unless the LEDs are pulsed and actually draw less current! Disassembly of the torch revealed a sturdy brushed geared electric motor, measured as providing about 9V DC at some 200-300mA to a simple 12V lamp dummy load. While not 0.5A, this output (say 6V <at> 0.25A) hence satisfies the magical 1W energy budget our emergency quest demands. A 4-diode rectifier bridge on the lamp’s PC board ensures unidirectional generator output (along with two 0.6V voltage drops), and soldering across two diodes readily allows external connections to be made. For even more efficiency you could replace the four diodes with suitably rated Schottky diodes, with their much lower (~0.1V) forward voltage drop. However, these devices are fairly expensive. Many mobile phones and UHF transceivers now idle at just a few milliamps on squelched receive, so almost a 50:1 energy benefit could result. Typically, a minute’s winding (about all you’d get away with on a peakhour train before dirty looks develop!) should extend reception by about half an hour. Outgoing transmissions will be power hogs, so text messages may be the best energy investment (although a “minutes winding for a minutes talk” may be tolerable in an emergency). As a bonus the 5V or so delivered by this modified “1 Watt Wonder” can also charge up to four normal AA or AAA NiMH/NiCds. You need to appreciate charging maths – dead flat cells, of say 1200mAh capacity, will need hours of unrealistic winding to bring to full charge. But even five minutes may be enough to persuade your digital camera to snap that trophy shot, find your dropped car keys, phone your mates or – phew – call the rescue chopper. SC I see the light! Here’s where I got lucky: a call to Jaycar Electronics revealed a Swiss-designed BENEX Dynamo LED torch – Cat ST3337 – amongst their superb lighting range, priced around $AU30. Aside from the torch’s normal multiple 15,000mCd lighting options, a sturdy handle folds out to hand charge the unit’s internal 3.6V Li-Ion battery. Claims that “1 minute wind-up = 30 minutes lighting” imply a 30:1 charge/ discharge ratio, so that a 20-30mA drain LED may indicate a dynamo siliconchip.com.au We found a pair of banana sockets (polarised of course) with matching banana plugs gave the best result. There’s room inside the torch for a variety of small sockets. November 2004  95 Vintage Radio By RODNEY CHAMPNESS, VK3UG Those troublesome capacitors, Pt.2 Some vintage radio receivers are far more tolerant of leaky capacitors than others. It all depends on the circuit configuration and the role of each individual capacitor. L AST MONTH, WE LOOKED at the problems paper capacitors can cause in vintage radios, often because they have become electrically leaky. Paper capacitors are troublesome and require replacement more often than other components, although perhaps not as often as many people believe. We also looked at the Healing R401E, a vintage radio receiver that can operate successfully with quite leaky capacitors. This month, we take a look at the Healing 505E, which isn’t quite so forgiving. The Healing 505E As shown in Fig.2, this set is quite different to its older brother. We’ll start by considering capacitors C5 and C12. These are screen bypasses and the leakage across C12 should not be less than 20 x R4 (ie, 20 x 100kΩ) which is equivalent to 2MΩ. If C12’s resistance is much less than this, the voltage on the 6BA6’s screen will be noticeably less than intended and the performance of the set will suffer. By contrast, C5’s leakage can be somewhat greater (less resistance), as R2 is only 22kΩ. C4 (the AGC bypass) is supplied with AGC voltage via R7 (1MΩ) and both the 6BE6 and 6BA6 valves receive back bias via a combination of R7 and R8. If C4 were to become leaky to any extent, the bias on the valves would A high-voltage tester is necessary for testing capacitor leakage resistance. 96  Silicon Chip be reduced. As a result, they would work harder and the set could become unstable and oscillate. Basically, if C4 is leaky, the voltage across R7 increases. If the leakage is bad enough, little AGC bias will be applied to the two valves and this will cause distortion and other problems. In fact, I have always considered the AGC bypass capacitor to be a very important. In this case, it should have a minimum leakage resistance of 20 x (1 + 1)MΩ, or 40MΩ (R7 and R8 are both 1MΩ resistors). My practice is to replace the AGC capacitor without even testing it and I like it to have a leakage resistance of at least 100MΩ. In fact, I usually replace AGC bypasses with 50V disc ceramic capacitors. They are reliable and easily hidden under other components. An interesting fault We now come to capacitor C15 which couples the audio from the detector to the first audio stage (6AV6). The maximum voltage across this capacitor will be no more than about 20V and yet it is rated at 600V! Note also that the grid resistor (R11) for the 6AV6 is a 10MΩ unit. Why so high you might ask? The answer is that the valve itself develops contact potential bias and the desired bias is obtained by connecting a 10MΩ resistor from grid to earth/cathode. However, such a high resistance means that the leakage across C15 must be around 200MΩ or more, if the valve bias is not to be upset. Note that most multimeters will be struggling to measure this amount of resistance. This is a very high impedance part of the receiver circuit. OK, I’ve said that the voltage across this capacitor is no more than around 20V and that’s with a very strong station tuned in. An interesting fault siliconchip.com.au Fig.1: unlike the Healing R401E, the circuit operation of the 505E model is easily upset by leaky capacitors. shows up when this capacitor is moderately leaky. With a relatively weak station, everything appears to be normal – the volume increases as the volume control is advanced. However, when a strong station is tuned in, the volume decreases as the volume control is advanced and it may even completely disappear as the control is rotated to maximum. Now that is an interesting fault! Let’s see how this occurs. As shown on Fig.1, the volume control (R6) wiper taps off a variable amount of audio and negative voltage relative to earth. This variable negative voltage is applied to the bottom end of C15, while the top end has around -1V on it relative to earth (ie, the contact potential bias). Now let’s assume that the voltage developed at the top of R6 (relative to earth) is -15V and that the wiper is at this position (ie, maximum volume). Further, let’s say that the leakage resistance across C15 is RL. In operation, RL siliconchip.com.au and R11 will act as a voltage divider across R6. As a result, the voltage at the junction of C15 and R11 is [R11/ (RL + R11)] x -15V. OK, now let’s assume that C15’s leakage resistance (RL) is 50MΩ. By plugging this figure into the above equation, we get [10MΩ/(50MΩ + 10MΩ)] x -15V = -2.5V. If this is added to the existing -1V contact potential bias, it means that the there could be as much as -3.5V of bias on the 6AV6. In practice, however, the voltage will be probably be somewhere between -2.5V and -3.5V. But even -2.5V is enough to cut off a 6AV6 in this circuit, resulting in no output on a strong signal at “full” volume! In fact, even 100MΩ of leakage resistance in C15 will dramatically alter the operating conditions of the 6AV6. Second audio coupler Capacitor C19 – the audio coupler Disc ceramic capacitors are ideal for use as AGC bypasses. They are reliable, have very low leakage and easily hidden under other components. between the plate of the 6AV6 and the grid of the following 6BV7 – also needs to have quite low leakage (ie, high resistance). This is necessary for the 6BV7 to work correctly. Resistor R13 is 470kΩ, so by my normal rule of thumb, C19 must not November 2004  97 Photo Gallery: General Electric Duette Manufactured in 1934 by AWA, the “Duette” was a 5-valve reflexed superhet receiver that was electrically equivalent to the AWA Radiolette Model 27. The valve line-up was as follows: 78 RF amplifier, 6A7 frequency changer, 6B7 reflexed IF/audio amplifier/detector/ AVC rectifier, 42 audio output and 80 rectifier. Photo: Historical Radio Society of Australia, Inc. have less than 20 times this resistance to be satisfactory – ie, about 10MΩ. However, in this case, the rule breaks down. Let’s find out why. First, the plate of the 6AV6 is at about +70V and, assuming that C19 has a leakage resistance of 10MΩ, this means that +3.3V will be developed across R13 (this is calculated using the same formula listed above). This means that with -4.5V of bias on the 6BV7’s grid and +3.3V R13, the 6BV7 will have around -1.2V of bias. In reality, it will actually be higher than this, as the valve will draw excessive current through the back bias network. As a result, both the power supply and the 6BV7 will be considerably overloaded and expensive 98  Silicon Chip fireworks could easily occur. So my rule of thumb of allowing a resistance of 20 times the value of any resistor associated with the capacitor is seriously in error in this case - just as it was with the coupling capacitor to the first audio grid. Even if the leakage resistance were 200 times the value of R13, the voltage developed across R13 would still be +0.33V, which is enough to slightly upset a high-gain short grid base valve such as the 6BV7. As a result, in this location, I expect to see at least 100MΩ of leakage resistance. You can now see why I am rather paranoid about the condition of the audio coupling capacitors. Other critical capacitors C18, a 400V mica capacitor, is intended to filter out most of the remaining 455kHz energy in the audio amplifier. Mica capacitors are usually quite reliable but when they do play up, they can be difficult to fault-find. In this position, the usual effect is a “crackle” in the sound. Tested with a normal multimeter, it may show no leakage resistance and its capacitance may be at the marked value. However, a high-voltage tester will often detect abnormal and varying leakage resistance across the capacitor. C23 from the plate of the 6BV7 to earth has the normal HT voltage applied across it plus the peak audio voltage. This means that this capacitor needs to be rated much higher than the circuit’s HT voltage and about double this voltage is the recommended figure. As a result, a 600V paper capacitor is usually fitted here. If its leakage resistance is relatively low, this capacitor can get quite hot and can go short circuit. C17 is the RF bypass across the HT line and has the full HT DC voltage applied across it at all times. Theoretically, it can be very leaky and still function OK. However, if a capacitor is too leaky, it will behave as though there is also a resistor inside its case. As a result, it will heat up and this can have a cumulative effect – as it gets hotter, its resistance drops and so it gets even hotter. This can easily develop into a runaway scenario and the capacitor needs to be replaced “pronto”. A word of caution is needed here. Before checking whether a capacitor has become warm to the touch, do the following things for your safety: (1.) Turn the set off and remove the power plug from the power point (if the set is left connected to the power point, 240VAC could still be lurking in the receiver waiting for an unwary finger to touch it!); (2.) Make sure that the high-tension (HT) voltage has disappeared (check the HT line with your multimeter). Only then can you can put your “pinkie” on the insulated case of the capacitor to check whether it has become warm or not. A time-honoured technique is worthy of mention here – when probing around the inside of a set, keep one hand in your pocket. This is particularly important when using a test instrument on a live receiver. Finally, C22 in the tone control circuit can be quite leaky and will siliconchip.com.au VALVES AUDIO HI-FI AMATEUR RADIO GUITAR AMPS INDUSTRIAL VINTAGE RADIO We can supply your valve needs, including high voltage capacitors, Hammond transformers, chassis, sockets and valve books. WE BUY, SELL and TRADE SSAE DL size for CATALOGUE Polyester capacitors come in all sorts of sizes and voltage ratings. They have low leakage (although not as good as polystyrene types), are generally very reliable and can be easily hidden inside the cases of defunct paper capacitors. have little effect on the operation of the control. In summary, unlike the older R401E model, the Healing 505E generally cannot tolerate leaky paper capacitors. The audio coupling capacitors in particular are critical and these and a number of others need to be carefully tested. In some cases, it even pays to replace them as a matter of course. Replacement capacitors A 1nF (.001µF) capacitor must have a lot less leakage current through it than, say, a 270nF (0.27µF) capacitor. My rule of thumb is that no paper capacitor should have less than 2MΩ leakage resistance, while a 1nF capacitor should have at least 1020MΩ minimum leakage resistance (as should other similar low-value capacitors). However, it does depend on just where it’s going to be used in the circuit. Some brands of capacitors were more prone to leakage than others. Ducon capacitors in the 1940s, 1950s and early 1960s were notorious for becoming leaky. UCCs were also sometimes leaky but more commonly became intermittent. By contrast, the older Chanex capacitors seem to be more reliable and some of the “moulded mud” AWAs were OK as well, although many split their cases. So what caused some brands of capacitors from certain periods to have a bad reputation? Frankly, I don’t know, although I do have some thoughts on siliconchip.com.au the matter. Perhaps someone who was employed in that part of the industry could enlighten me. The Philips polyester capacitors that came onto the market in the early 1960s were a quantum leap forward as a replacement for the paper capacitors. Their reliability and low leakage is well known, although I had a polyester unit unexpectedly blow up just recently. There was smoke every-where from it and the resistor that also burnt out when it failed (it went off like bunger). However, that’s just something that happens sometimes and polyester capacitors really are very reliable. There is no doubt that valve radios would have carried on for much longer if they had been available much earlier (ie, when the radios were manufactured). ELECTRONIC VALVE & TUBE COMPANY PO Box 487 Drysdale, Vic 3222 76 Bluff Rd, St Leonards, 3223 Tel: (03) 5257 2297; Fax: (03) 5257 1773 Email: evatco<at>pacific.net.au www.evatco.com.au Testing capacitors There are two test procedures that will usually sort good paper capacitors from the bad ones. A check of the resistance between the two terminals of the capacitor is one such test. However, a normal multimeter will not give a reliable indication of the leakage resistance, as the applied voltage will be no higher than around 9V. Instead, it must be done using a high-voltage tester. Altronics have such a high-voltage tester as a kit (Cat. K-2555) and the price is quite reasonable. It can test capacitors for leakage at either 500V or 1000V and is invaluable for test- ing nearly all capacitors other than electrolytics. A high-voltage test will usually show up any capacitor with a leakage resistance of 200MΩ or less. 200V capacitors can be tested on the 500V range, as they usually have a peak rating well in excess of their normal operating voltage. Similarly, 400V units can be tested at 500V, while 600V (or 630V) capacitors can tested at 1000V. Heat also has quite an effect on the leakage resistance of a capacitor. Some November 2004  99 earth when the capacitor was used as a bypass – or alternatively, the end that should connect to the lower impedance part of the circuit. Why was that? Well, the band indicated the pigtail lead that was connected to the capacitor’s outer foil. This outer foil (when earthed) acts as a shield, thereby reducing RF radiation when the capacitor is used as a bypass or filter. Summary A selection of mica capacitors. Mica capacitors are usually quite reliable but when they do play up, they can be difficult to fault-find. time ago, I salvaged all the paper capacitors from an old valve b&w TV set. To test them, I first heated them in an oven to about 70°C then checked them using a conventional ohmmeter. Did I get a shock – they had all tested OK when cold but it was an entirely different story after they came out of the oven. I ended up throwing the lot in the bin. By contrast, the polyester capacitors I had salvaged from the same set were quite OK. Checking in-situ Checking capacitors in-situ (eg, in an old radio) involves first lifting one end of each capacitor in turn before checking it with the high-voltage tester. They can also be heated with a hair-drier so that they are warm (but not hot) and the checks repeated. You will soon discover whether a capacitor is worth leaving in the set or not. A larger-value capacitor acting as (say) an HT RF bypass can be left in the set after passing a leakage test. It can then be reconnected, after which the set can be switched on and the HT voltage checked. If the HT is OK, wait a few minutes, then switch the set off and disconnect it from the mains. Finally, check that the HT rail has disappeared (use a multimeter) before checking the HT bypasses and electrolytic capacitors to see if any are warm. If they are, it signals that the units are too leaky and need replacing. Why the high voltage? As mentioned earlier, the Healing 505E uses several high-voltage paper capacitors in relatively low-voltage sections of the circuit. The reason for this is that the high-voltage units had better insulation and therefore less leakage (ie, higher resistance) than low-voltage types. As a result, highvoltage capacitors were used where low leakage was critical to the set’s performance. By the way, I have also found that paper capacitors have less leakage when only a low voltage is applied across them. As the voltage across them increases, so does their leakage. “Earthy” end A selection of polystyrene capacitors made by Ducon. Polystyrene capacitors have extremely low leakage. 100  Silicon Chip Paper capacitors often had a (black) band at one end of the capacitor. This indicated the end that should go to (1.) The leakage resistance of a paper capacitor depends on the voltage across it, its voltage rating, its capacitance and its temperature. (2.) The circuit position dictates how leaky a paper capacitor can be and still be considered satisfactory. Audio coupling capacitors and AGC bypasses, in particular can have very little leakage, with a leakage resistance of around 100MΩ or more being the minimum acceptable resistance. This is to ensure that there is little or no alteration to the operating conditions of the part of the circuit they connect to. By contrast, bypass capacitors can be quite leaky (a cathode bypass can be down to several kilohms in some cases and still operate satisfactorily). However, I recommend a minimum resistance of around 2MΩ for these capacitors. (3.) A capacitor’s leakage resistance will reduce (ie, the current through it will increase) when used in a set due to internal heating, particularly if the capacitor is relatively leaky. I consider a leakage resistance of at least 1-2MΩ to be the minimum for a large paper capacitor but this should considerably higher for low-value capacitors. (4.) The circuit design will dictate how leaky the paper capacitor can be in certain location for the receiver to operate normally. Note the comparison between the Healing 505E and the Healing R401E described last month. (5.) To ensure authenticity, keep at least some non-critical paper capacitors in a set. A good trick is to remove the internals of paper capacitors and fit polyester capacitors (which are physically smaller) inside the cases of the old capacitors. That’s it on the subject of paper capacitors. We’ll cover electrolytic, mica and other lesser-known capacitors in a future article a little further SC down the track. siliconchip.com.au siliconchip.com.au November 2004  101 Silicon Chip Back Issues November 1994: Dry Cell Battery Rejuvenator; Novel Alphanumeric Clock; 80-M DSB Amateur Transmitter; 2-Cell Nicad Discharger. April 1989: Auxiliary Brake Light Flasher; What You Need to Know About Capacitors; 32-Band Graphic Equaliser, Pt.2. April 1992: IR Remote Control For Model Railroads; Differential Input Buffer For CROs; Aligning Vintage Radio Receivers, Pt.1. May 1989: Build A Synthesised Tom-Tom; Biofeedback Monitor For Your PC; Simple Stub Filter For Suppressing TV Interference. 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. July 1989: Exhaust Gas Monitor; Experimental Mains Hum Sniffers; Compact Ultrasonic Car Alarm; The NSW 86 Class Electrics. September 1989: 2-Chip Portable AM Stereo Radio Pt.1; High Or Low Fluid Level Detector; Studio Series 20-Band Stereo Equaliser, Pt.2. 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. October 1989: FM Radio Intercom For Motorbikes Pt.1; GaAsFet Preamplifier For Amateur TV; 2-Chip Portable AM Stereo Radio, Pt.2. 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. 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. March 1993: Solar Charger For 12V Batteries; Reaction Trainer; Audio Mixer for Camcorders; A 24-Hour Sidereal Clock For Astronomers. January 1990: High Quality Sine/Square Oscillator; Service Tips For Your VCR; Active Antenna Kit; Designing UHF Transmitter Stages. 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. 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. April 1990: Dual Tracking ±50V Power Supply; Voice-Operated Switch With Delayed Audio; 16-Channel Mixing Desk, Pt.3; Active CW Filter. June 1990: Multi-Sector Home Burglar Alarm; Build A Low-Noise Universal Stereo Preamplifier; Load Protector For Power Supplies. July 1993: Single Chip Message Recorder; Light Beam Relay Extender; AM Radio Trainer, Pt.2; Quiz Game Adjudicator; Antenna Tuners – Why They Are Useful. 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. August 1993: Low-Cost Colour Video Fader; 60-LED Brake Light Array; Microprocessor-Based Sidereal Clock; 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. September 1990: 3-Digit Counter Module; Simple Shortwave Converter For The 2-Metre Band; Taking Care Of Nicad Battery Packs. December 1993: Remote Controller For Garage Doors; LED Stroboscope; 25W Audio Amplifier Module; A 1-Chip Melody Generator; Engine Management, Pt.3; Index To Volume 6. 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. 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. September 1991: Digital Altimeter For Gliders & Ultralights; Ultrasonic Switch For Mains Appliances; The Basics Of A/D & D/A Conversion. October 1991: 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. 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; A Talking Voltmeter For Your PC, Pt.2. December 1991: TV Transmitter For VCRs With UHF Modulators; IR Light Beam Relay; Colour TV Pattern Generator, Pt.2; Index To Vol.4. March 1992: TV Transmitter For VHF VCRs; Thermostatic Switch For Car Radiator Fans; Valve Substitution In Vintage Radios. ORDER FORM April 1995: FM Radio Trainer, Pt.1; Balanced Mic Preamp & Line Filter; 50W/Channel Stereo Amplifier, Pt.2; Wide Range Electrostatic Loudspeakers, Pt.3; 8-Channel Decoder For Radio Remote Control. 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. 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. March 1991: Transistor Beta Tester Mk.2; A Synthesised AM Stereo Tuner, Pt.2; Multi-Purpose I/O Board For PC-Compatibles; Wideband RF Preamplifier For Amateur Radio & TV. March 1995: 2 x 50W 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. June 1993: AM Radio Trainer, Pt.1; Remote Control For The Woofer Stopper; Digital Voltmeter For Cars. 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. January 1991: Fast Charger For Nicad Batteries, Pt.1; Have Fun With The Fruit Machine (Simple Poker Machine); Two-Tone Alarm Module; The Dangers of Servicing Microwave Ovens. February 1995: 2 x 50W 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. May 1995: 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. 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 1990: Connecting Two TV Sets To One VCR; Build An Egg Timer; Low-Cost Model Train Controller; 1.5V To 9V DC Converter; Introduction To Digital Electronics; A 6-Metre Amateur Transmitter. January 1995: Sun Tracker For Solar Panels; Battery Saver For Torches; Dual Channel UHF Remote Control; Stereo Microphone Pre­amp­lifier. April 1993: Solar-Powered Electric Fence; Audio Power Meter; ThreeFunction Home Weather Station; 12VDC To 70VDC Converter. July 1990: Digital Sine/Square Generator, Pt.1 (0-500kHz); Burglar Alarm Keypad & Combination Lock; Build A Simple Electronic Die; 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. December 1994: 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. August 1995: Fuel Injector Monitor For Cars; Gain Controlled Microphone Preamp; How To Identify IDE Hard Disk Drive Parameters. September 1995: Railpower Mk.2 Walkaround Throttle For Model Railways, Pt.1; Keypad Combination Lock; Jacob’s Ladder Display. October 1995: 3-Way Loudspeaker System; Railpower Mk.2 Walkaround Throttle For Model Railways, Pt.2; Nicad Fast Charger. 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 1994:90-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. November 1995: Mixture Display For Fuel Injected Cars; CB Trans­verter For The 80M Amateur Band, Pt.1; PIR Movement Detector. December 1995: Engine Immobiliser; 5-Band Equaliser; CB Transverter For The 80M Amateur Band, Pt.2; Subwoofer Controller; Knock Sensing In Cars; Index To Volume 8. January 1996: Surround Sound Mixer & Decoder, Pt.1; Magnetic Card Reader; Automatic Sprinkler Controller; IR Remote Control For The Railpower Mk.2; Recharging Nicad Batteries For Long Life. April 1996: 125W Audio Amplifier Module; Knock Indicator For Leaded Petrol Engines; Multi-Channel Radio Control Transmitter; Pt.3. May 1996: High Voltage Insulation Tester; Knightrider LED Chaser; Simple Intercom Uses Optical Cable; Cathode Ray Oscilloscopes, Pt.3. June 1996: Stereo Simulator (uses delay chip); Rope Light Chaser; Low Ohms Tester For Your DMM; Automatic 10A Battery Charger. April 1994: Sound & Lights For Model Railway Level Crossings; 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. June 1994: 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. July 1996: VGA Digital Oscilloscope, Pt.1; Remote Control Extender For VCRs; 2A SLA Battery Charger; 3-Band Parametric Equaliser;. August 1996: 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; 600W DC-DC Converter For Car Hifi Systems, Pt.1; IR Stereo Headphone Link, Pt.2; Multi-Channel Radio Control Transmitter, Pt.8. July 1994: Build A 4-Bay Bow-Tie UHF TV Antenna; PreChamp 2-Transistor Preamplifier; Steam Train Whistle & Diesel Horn Simulator; 6V SLA Battery Charger; Electronic Engine Management, Pt.10. August 1994: High-Power Dimmer For Incandescent Lights; Dual Diversity Tuner For FM Microphones, Pt.1; Nicad Zapper (For Resurrecting Nicad Batteries); Electronic Engine Management, Pt.11. September 1994: Automatic Discharger For Nicad Batteries; MiniVox Voice Operated Relay; AM Radio For Weather Beacons; Dual Diversity Tuner For FM Mics, Pt.2; Electronic Engine Management, Pt.12. October 1994: How Dolby Surround Sound Works; Dual Rail Variable Power Supply; Talking Headlight Reminder; Electronic Ballast For Fluorescent Lights; Electronic Engine Management, Pt.13. November 1996: 8-Channel Stereo Mixer, Pt.1; Low-Cost Fluorescent Light Inverter; Repairing Domestic Light Dimmers; 600W DC-DC Converter For Car Hifi Systems, Pt.2. December 1996: Active Filter For CW Reception; Fast Clock For Railway Modellers; Laser Pistol & Electronic Target; Build A Sound Level Meter; 8-Channel Stereo Mixer, Pt.2; Index To Vol.9. January 1997: How To Network Your PC; Control Panel For Multiple Smoke Alarms, Pt.1; Build A Pink Noise Source; Computer Controlled Dual Power Supply, Pt.1; Digi-Temp Monitors Eight Temperatures. February 1997: PC-Con­trolled Moving Message Display; Computer Please send the following back issues:________________________________________ Enclosed is my cheque/money order for $­______or please debit my:  Bankcard  Visa Card  Master Card Card No. Signature ___________________________ Card expiry date_____ /______ Name ______________________________ Phone No (___) ____________ PLEASE PRINT Street ______________________________________________________ Suburb/town _______________________________ Postcode ___________ 102  Silicon Chip 10% OF SUBSCR F TO IB OR IF Y ERS OU 10 OR M BUY ORE Note: prices include postage & packing Australia ............................... $A8.80 (incl. GST) Overseas (airmail) ..................................... $A10 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 siliconchip.com.au Controlled Dual Power Supply, Pt.2; Alert-A-Phone Loud Sounding Telephone Alarm; Control Panel For Multiple Smoke Alarms, Pt.2. 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. 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. May 1997: 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; TV Pattern Generator, Pt.1; Audio/RF Signal Tracer; High-Current Speed Controller For 12V/24V Motors; Manual Control Circuit For Stepper Motors. July 1997: Infrared Remote Volume Control; A Flexible Interface Card For PCs; Points Controller For Model Railways; Colour TV Pattern Generator, Pt.2; An In-Line Mixer For Radio Control Receivers. 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. October 1997: 5-Digit Tachometer; Central Locking For Your Car; PCControlled 6-Channel Voltmeter; 500W Audio Power Amplifier, Pt.3. November 1997: Heavy Duty 10A 240VAC Motor Speed Controller; Easy-To-Use Cable & Wiring Tester; Build A Musical Doorbell; Replacing Foam Speaker Surrounds; Understanding Electric Lighting Pt.1. December 1999: Solar Panel Regulator; PC Powerhouse (gives +12V, +9V, +6V & +5V rails); Fortune Finder Metal Locator; Speed Alarm For Cars, Pt.2; Railpower Model Train Controller, Pt.3; Index To Vol.12. January 2000: Spring Reverberation Module; An Audio-Video Test Generator; Parallel Port Interface Card; Telephone Off-Hook Indicator. November 2002: SuperCharger For NiCd/NiMH Batteries, Pt.1; Windows-Based EPROM Programmer, Pt.1; 4-Digit Crystal-Controlled Timing Module; Using Linux To Share An Optus Cable Modem, Pt.1. March 2000: Resurrecting An Old Computer; 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. December 2002: Receiving TV From Satellites; Pt.1; The Micromitter Stereo FM Transmitter; Windows-Based EPROM Programmer, Pt.2; SuperCharger For NiCd/NiMH Batteries; Pt.2; Simple VHF FM/AM Radio; Using Linux To Share An Optus Cable Modem, Pt.2. May 2000: Ultra-LD Stereo Amplifier, Pt.2; LED Dice (With PIC Microcontroller); Low-Cost AT Keyboard Translator (Converts IBM Scan-Codes To ASCII); 50A Motor Speed Controller For Models. June 2000: Automatic Rain Gauge; Parallel Port VHF FM Receiver; Switchmode Power Supply (1.23V to 40V) Pt.1; CD Compressor. July 2000: Moving Message Display; Compact Fluorescent Lamp Driver; Musicians’ Lead Tester; Switchmode Power Supply, Pt.2. September 2000: Swimming Pool Alarm; 8-Channel PC Relay Board; Fuel Mixture Display For Cars, Pt.1; Protoboards – The Easy Way Into Electronics, Pt.1; Cybug The Solar Fly. April 2003: Video-Audio Booster For Home Theatre Systems; Telephone Dialler For Burglar Alarms; Three PIC Programmer Kits; PICAXE, Pt.3 (Heartbeat Simulator); Electric Shutter Release For Cameras. October 2000: Guitar Jammer; Breath Tester; Wand-Mounted Inspection Camera; Subwoofer For Cars; Fuel Mixture Display, Pt.2. May 2003: Widgybox Guitar Distortion Effects Unit; 10MHz Direct Digital Synthesis Generator; Big Blaster Subwoofer; Printer Port Simulator; PICAXE, Pt.4 (Motor Controller). December 2000: Home Networking For Shared Internet Access; White LED Torch; 2-Channel Guitar Preamplifier, Pt.2 (Digital Reverb); Driving An LCD From The Parallel Port; Index To Vol.13. June 1998: Troubleshooting Your PC, Pt.2; Universal High Energy Ignition System; The Roadies’ Friend Cable Tester; Universal Stepper Motor Controller; Command Control For Model Railways, Pt.5. July 1998: Troubleshooting Your PC, Pt.3; 15W/Ch Class-A Audio Amplifier, Pt.1; Simple Charger For 6V & 12V SLA Batteries; Auto­ matic Semiconductor Analyser; Understanding Electric Lighting, Pt.8. August 1998: Troubleshooting Your PC, Pt.4; I/O Card With Data Logging; Beat Triggered Strobe; 15W/Ch Class-A Stereo Amplifier, Pt.2. September 1998: Troubleshooting Your PC, Pt.5; A Blocked Air-Filter Alarm; Waa-Waa Pedal For Guitars; Jacob’s Ladder; Gear Change Indicator For Cars; Capacity Indicator For Rechargeable Batteries. October 1998: 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; A Turbo Timer For Cars; Build A Poker Machine, Pt.1; FM Transmitter For Musicians; Lab Quality AC Millivoltmeter, Pt.2; Improving AM Radio Reception, Pt.1. December 1998: Engine Immobiliser Mk.2; Thermocouple Adaptor For DMMs; Regulated 12V DC Plugpack; Build A Poker Machine, Pt.2; Improving AM Radio Reception, Pt.2; Mixer Module For F3B Gliders. February 2003: PortaPal PA System, Pt.1; SC480 50W RMS Amplifier Module, Pt.2; Windows-Based EPROM Programmer, Pt.3; Using Linux To Share An Optus Cable Modem, Pt.4; Fun With The PICAXE, Pt.1. March 2003: LED Lighting For Your Car; Peltier-Effect Tinnie Cooler; PortaPal PA System, Pt.2; 12V SLA Battery Float Charger; Little Dynamite Subwoofer; Fun With The PICAXE, Pt.2 (Shop Door Minder). January 1998: 4-Channel 12VDC or 12VAC Lightshow, Pt.1; Command Control For Model Railways, Pt.1; Pan Controller For CCD Cameras. May 1998: 3-LED Logic Probe; Garage Door Opener, Pt.2; Command Control System, Pt.4; 40V 8A Adjustable Power Supply, Pt.2. January 2003: Receiving TV From Satellites, Pt 2; SC480 50W RMS Amplifier Module, Pt.1; Gear Indicator For Cars; Active 3-Way Crossover For Speakers; Using Linux To Share An Optus Cable Modem, Pt.3. August 2000: Theremin; Spinner (writes messages in “thin-air”); Proximity Switch; Structured Cabling For Computer Networks. November 2000: Santa & Rudolf Chrissie Display; 2-Channel Guitar Preamplifier, Pt.1; Message Bank & Missed Call Alert; Protoboards – The Easy Way Into Electronics, Pt.3. April 1998: Automatic Garage Door Opener, Pt.1; 40V 8A Adjustable Power Supply, Pt.1; PC-Controlled 0-30kHz Sinewave Generator; Understanding Electric Lighting; Pt.6. October 2002: Speed Controller For Universal Motors; PC Parallel Port Wizard; Cable Tracer; AVR ISP Serial Programmer; 3D TV. February 2000: Multi-Sector Sprinkler Controller; A Digital Voltmeter For Your Car; Safety Switch Checker; Sine/Square Wave Oscillator. December 1997: Speed Alarm For Cars; 2-Axis Robot With Gripper; Stepper Motor Driver With Onboard Buffer; Power Supply For Stepper Motor Cards; Understanding Electric Lighting Pt.2; Index To Vol.10. February 1998: 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. September 2002: 12V Fluorescent Lamp Inverter; 8-Channel Infrared Remote Control; 50-Watt DC Electronic Load; Spyware – An Update. January 2001: How To Transfer LPs & Tapes To CD; The LP Doctor – Clean Up Clicks & Pops, Pt.1; Arbitrary Waveform Generator; 2-Channel Guitar Preamplifier, Pt.3; PIC Programmer & TestBed. February 2001: An Easy Way To Make PC Boards; L’il Pulser Train Controller; A MIDI Interface For PCs; Build The Bass Blazer; 2-Metre Groundplane Antenna; The LP Doctor – Clean Up Clicks & Pops, Pt.2. March 2001: Making Photo Resist PC Boards; Big-Digit 12/24 Hour Clock; Parallel Port PIC Programmer & Checkerboard; Protoboards – The Easy Way Into Electronics, Pt.5; A Simple MIDI Expansion Box. April 2001: A GPS Module For Your PC; Dr Video – An Easy-To-Build Video Stabiliser; Tremolo Unit For Musicians; Minimitter FM Stereo Transmitter; Intelligent Nicad Battery Charger. May 2001: 12V Mini Stereo Amplifier; Two White-LED Torches To Build; PowerPak – A Multi-Voltage Power Supply; Using Linux To Share An Internet Connection, Pt.1; Tweaking Windows With TweakUI. June 2003: PICAXE, Pt.5; PICAXE-Controlled Telephone Intercom; PICAXE-08 Port Expansion; Sunset Switch For Security & Garden Lighting; Digital Reaction Timer; Adjustable DC-DC Converter For Cars; Long-Range 4-Channel UHF Remote Control. July 2003: Smart Card Reader & Programmer; Power-Up Auto Mains Switch; A “Smart” Slave Flash Trigger; Programmable Continuity Tester; PICAXE Pt.6 – Data Communications; Updating The PIC Programmer & Checkerboard; RFID Tags – How They Work. August 2003: PC Infrared Remote Receiver (Play DVDs & MP3s On Your PC Via Remote Control); Digital Instrument Display For Cars, Pt.1; Home-Brew Weatherproof 2.4GHz WiFi Antennas; PICAXE Pt.7. September 2003: Robot Wars; Krypton Bike Light; PIC Programmer; Current Clamp Meter Adapter For DMMs; PICAXE Pt.8 – A Data Logger; Digital Instrument Display For Cars, Pt.2. October 2003: PC Board Design, Pt.1; JV80 Loudspeaker System; A Dirt Cheap, High-Current Power Supply; Low-Cost 50MHz Frequency Meter; Long-Range 16-Channel Remote Control System. November 2003: PC Board Design, Pt.2; 12AX7 Valve Audio Preamplifier; Our Best Ever LED Torch; Smart Radio Modem For Microcontrollers; PICAXE Pt.9; Programmable PIC-Powered Timer. June 2001: Universal Battery Charger, Pt.1; Phonome – Call, Listen In & Switch Devices On & Off; Low-Cost Automatic Camera Switcher; Using Linux To Share An Internet Connection, Pt.2; A PC To Die For, Pt.1. December 2003: How To Receive Weather Satellite Images; Self-Diagnostics Plug For Cars; PC Board Design, Pt.3; VHF Receiver For Weather Satellites; Linear Supply For Luxeon 1W Star LEDs; MiniCal 5V Meter Calibration Standard; PIC-Based Car Battery Monitor; PICAXE Pt.10. July 2001: The HeartMate Heart Rate Monitor; Do Not Disturb Tele­phone Timer; Pic-Toc – A Simple Alarm Clock; Fast Universal Battery Charger, Pt.2; A PC To Die For, Pt.2; Backing Up Your Email. January 2004: Studio 350W Power Amplifier Module, Pt.1; HighEfficiency Power Supply For 1W Star LEDs; Antenna & RF Preamp For Weather Satellites; Lapel Microphone Adaptor For PA Systems; PICAXE-18X 4-Channel Datalogger, Pt.1; 2.4GHZ Audio/Video Link. August 2001: DI Box For Musicians; 200W Mosfet Amplifier Module; Headlight Reminder; 40MHz 6-Digit Frequency Counter Module; A PC To Die For, Pt.3; Using Linux To Share An Internet Connection, Pt.3. September 2001: Making MP3s; Build An MP3 Jukebox, Pt.1; PCControlled Mains Switch; Personal Noise Source For Tinnitus; Directional Microphone; Using Linux To Share An Internet Connection, Pt.4. February 2004: PC Board Design For Beginners, Pt.1; Simple Supply Rail Monitor For PCs; Studio 350W Power Amplifier Module, Pt.2; Fantastic Human-Powered LED Torches; Shorted Turns Tester For Line Output Transformers; PICAXE-18X 4-Channel Datalogger, Pt.2. March 2004: PC Board Design For Beginners, Pt.2; Build The QuickBrake For Increased Driving Safety; 3V-9V (or more) DC-DC Converter; ESR Meter Mk.2, Pt.1; PICAXE-18X 4-Channel Datalogger, Pt.3. January 1999: High-Voltage Megohm Tester; A Look At The BASIC Stamp; Bargraph Ammeter For Cars; Keypad Engine Immobiliser. November 2001: Ultra-LD 100W/Channel Stereo Amplifier, Pt.1; Neon Tube Modulator For Cars; Audio/Video Distribution Amplifier; Build A Short Message Recorder Player; Useful Tips For Your PC. March 1999: Build A Digital Anemometer; DIY PIC Programmer; Easy-To-Build Audio Compressor; Low-Distortion Audio Signal Generator, Pt.2. December 2001: IR Transceiver For PCs; 100W/Ch Stereo Amplifier, Pt.2; Pardy Lights Colour Display; PIC Fun – Learning About Micros. April 2004: PC Board Design For Beginners, Pt.3; Loudspeaker Level Meter For Home Theatre Systems; Shut That Mutt (Electronic Dog Silencer); Smart Mixture Display For Cars; ESR Meter Mk.2, Pt.2; PC/ PICAXE Interface For UHF Remote Control. January 2002: Touch And/Or Remote-Controlled Light Dimmer, Pt.1; A Cheap ’n’Easy Motorbike Alarm; 100W /Channel Stereo Amplifier, Pt.3; Build A Raucous Alarm; FAQs On The MP3 Jukebox. May 2004: Amplifier Testing Without High-Tech Gear; Component Video To RGB Converter; Starpower Switching Supply For Luxeon Star LEDs; Wireless Parallel Port; Poor Man’s Metal Locator. February 2002: 10-Channel IR Remote Control Receiver; 2.4GHz High-Power Audio-Video Link; Touch And/Or Remote-Controlled Light Dimmer, Pt.2; Booting A PC Without A Keyboard; 4-Way Event Timer. June 2004: Dr Video Mk.2 Video Stabiliser; Build An RFID Security Module; Fridge-Door Alarm; Courtesy Light Delay For Cars; Automating PC Power-Up; Upgraded Software For The EPROM Programmer. 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. March 2002: Mighty Midget Audio Amplifier Module; 6-Channel IR Remote Volume Control, Pt.1; RIAA Pre­-­Amplifier For Magnetic Cartridges; 12/24V Intelligent Solar Power Battery Charger. July 2004: Silencing A Noisy PC; Versatile Battery Protector; Appliance Energy Meter, Pt.1; A Poor Man’s Q Meter; Regulated High-Voltage Supply For Valve Amplifiers; Remote Control For A Model Train Layout. July 1999: Build A Dog Silencer; 10µH to 19.99mH Inductance Meter; Audio-Video Transmitter; Programmable Ignition Timing Module For Cars, Pt.2; XYZ Table With Stepper Motor Control, Pt.3. April 2002:Automatic Single-Channel Light Dimmer; Pt.1; Water Level Indicator; Multiple-Output Bench Power Supply; Versatile Multi-Mode Timer; 6-Channel IR Remote Volume Control, Pt.2. August 2004: Video Formats: Why Bother?; VAF’s New DC-X Generation IV Loudspeakers; Video Enhancer & Y/C Separator; Balanced Microphone Preamp; Appliance Energy Meter, Pt.2; 3-State Logic Probe. 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. May 2002: 32-LED Knightrider; The Battery Guardian (Cuts Power When the Battery Voltage Drops); Stereo Headphone Amplifier; Automatic Single-Channel Light Dimmer; Pt.2; Stepper Motor Controller. September 2004: Voice Over IP (VoIP) For Beginners; WiFry – Cooking Up 2.4GHz Antennas; Bed Wetting Alert; Build a Programmable Robot; Another CFL Inverter. September 1999: 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. June 2002: Lock Out The Bad Guys with A Firewall; Remote Volume Control For Stereo Amplifiers; The “Matchless” Metal Locator; Compact 0-80A Automotive Ammeter; Constant High-Current Source. October 2004: The Humble “Trannie” Turns 50; SMS Controller, Pt.1; RGB To Component Video Converter; USB Power Injector; Remote Controller For Garage Doors & Gates. October 1999: 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. July 2002: Telephone Headset Adaptor; Rolling Code 4-Channel UHF Remote Control; Remote Volume Control For The Ultra-LD Stereo Amplifier; Direct Conversion Receiver For Radio Amateurs, Pt.1. November 1999: Setting Up An Email Server; Speed Alarm For Cars, Pt.1; LED Christmas Tree; Intercom Station Expander; Foldback Loudspeaker System; Railpower Model Train Controller, Pt.2. August 2002: Digital Instrumentation Software For PCs; Digital Storage Logic Probe; Digital Therm./Thermostat; Sound Card Interface For PC Test Instruments; Direct Conversion Receiver For Radio Amateurs. 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. 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. siliconchip.com.au PLEASE NOTE: issues not listed have sold out. All other issues are in stock. We can supply photostat copies from sold-out issues for $8.80 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 can be downloaded free from our web site: www.siliconchip.com.au November 2004  103 ALL S ILICON C HIP SUBSCRIBERS – PRINT, OR BOTH – AUTOMATICALLY QUALIFY FOR A REFERENCE $ave 10%ONLINE DISCOUNT ON ALL BOOK OR PARTSHOP PURCHASES. CHIP BOOKSHOP 10% (Does not apply to subscriptions) SILICON For the latest titles and information, please refer to our website books page: www.siliconchip.com.au/Shop/Books PIC MICROCONTROLLERS: know it all SELF ON AUDIO Multiple authors $85.00 The best of subjects Newnes authors have written over the past few years, combined in a one-stop maxi reference. Covers introduction to PICs and their programming in Assembly, PICBASIC, MBASIC & C. 900+ pages. PROGRAMMING and CUSTOMIZING THE PICAXE By David Lincoln (2nd Ed, 2011) $65.00* A great aid when wrestling with applications for the PICAXE See series of microcontrollers, at beginner, intermediate and Review April advanced levels. Every electronics class, school and library should have a copy, along with anyone who works with PICAXEs. 300 pages in paperback. 2011 PIC IN PRACTICE by D W Smith. 2nd Edition - published 2006 $60.00* by Douglas Self 2nd Edition 2006 $69.00* A collection of 35 classic magazine articles offering a dependable methodology for designing audio power amplifiers to improve performance at every point without significantly increasing cost. Includes compressors/limiters, hybrid bipolar/FET amps, electronic switching and more. 467 pages in paperback. SMALL SIGNAL AUDIO DESIGN By Douglas Self – First Edition 2010 $95.00* The latest from the Guru of audio. Explains audio concepts in easy-to-understand language with plenty of examples and reasoning. Inspiration for audio designers, superb background for audio enthusiasts and especially where it comes to component peculiarities and limitations. Expensive? Yes. Value for money? YES! Highly recommended. 558 pages in paperback. Based on popular short courses on the PIC, for professionals, students and teachers. Can be used at a variety of levels. An ideal introduction to the world of microcontrollers. 255 pages in paperback. PIC MICROCONTROLLER – your personal introductory course By John Morton 3rd edition 2005. $60.00* A unique and practical guide to getting up and running with the PIC. It assumes no knowledge of microcontrollers – ideal introduction for students, teachers, technicians and electronics enthusiasts. Revised 3rd edition focuses entirely on re-programmable flash PICs such as 16F54, 16F84 12F508 and 12F675. 226 pages in paperback. AUDIO POWER AMPLIFIER DESIGN HANDBOOK by Douglas Self – 5th Edition 2009 $85.00* "The Bible" on audio power amplifiers. Many revisions and updates to the previous edition and now has an extra three chapters covering Class XD, Power Amp Input Systems and Input Processing and Auxiliarly Subsystems. Not cheap and not a book for the beginner but if you want the best reference on Audio Power Amps, you want this one! 463 pages in paperback. DVD PLAYERS AND DRIVES by K.F. Ibrahim. Published 2003. $71.00* OP AMPS FOR EVERYONE By Bruce Carter – 4th Edition 2013 $83.00* This is the bible for anyone designing op amp circuits and you don't have to be an engineer to get the most out of it. It is written in simple language but gives lots of in-depth info, bridging the gap between the theoretical and the practical. 281 pages, A guide to DVD technology and applications, with particular focus on design issues and pitfalls, maintenance and repair. Ideal for engineers, technicians, students of consumer electronics and sales and installation staff. 319 pages in paperback. by Sanjaya Maniktala, Published April 2012. $83.00 Thoroughly revised! The most comprehensive study available of theoretical and practical aspects of controlling and measuring EMI in switching power supplies. Subtitled Exploring the PIC32, a Microchip insider tells all on this powerful PIC! Focuses on examples and exercises that show how to solve common, real-world design problems quickly. Includes handy checklists. FREE CD-ROM includes source code in C, the Microchip C30 compiler, and MPLAB SIM. 400 pages paperback. By Garry Cratt – Latest (7th) Edition 2008 $49.00 Written in Australia, for Australian conditions by one of Australia's foremost satellite TV experts. If there is anything you wanted to know about setting up a satellite TV system, (including what you can't do!) it's sure to be covered in this 176-page paperback book. See Review Feb 2004 SWITCHING POWER SUPPLIES A-Z PROGRAMMING 32-bit MICROCONTROLLERS IN C By Luci di Jasio (2008) $79.00* PRACTICAL GUIDE TO SATELLITE TV See Review March 2010 ELECTRIC MOTORS AND DRIVES By Austin Hughes & Bill Drury - 4th edition 2013 $59.00* This is a very easy to read book with very little mathematics or formulas. It covers the basics of all the main motor types, DC permanent magnet and wound field, AC induction and steppers and gives a very good description of how speed control circuits work with these motors. Soft covers, 444 pages. NEWNES GUIDE TO TV & VIDEO TECHNOLOGY By KF Ibrahim 4th Edition (Published 2007) $49.00 It's back! Provides a full and comprehensive coverage of video and television technology including HDTV and DVD. Starts with fundamentals so is ideal for students but covers in-depth technologies such as Blu-ray, DLP, Digital TV, etc so is also perfect for engineers. 600+ pages in paperback. RF CIRCUIT DESIGN by Chris Bowick, Second Edition, 2008. $63.00* The classic RF circuit design book. RF circuit design is now more important that ever in the wireless world. In most of the wireless devices that we use there is an RF component – this book tells how to design and integrate in a very practical fashion. 244 pages in paperback. AC MACHINES By Jim Lowe Published 2006 $66.00* Applicable to Australian trades-level courses including NE10 AC Machines, NE12 Synchronous Machines and the AC part of NE30 Electric Motor Control and Protection. Covering polyphase induction motors, singlephase motors, synchronous machines and polyphase motor starting. 160 pages in paperback. PRACTICAL VARIABLE SPEED DRIVES & POWER ELECTRONICS Se e by Malcolm Barnes. 1st Ed, Feb 2003. $73.00* Review An essential reference for engineers and anyone who wishes to design or use variable speed drives for induction motors. 286 pages in soft cover. Feb 2003 BUILD YOUR OWN ELECTRIC MOTORCYCLE PRACTICAL RF HANDBOOK by Carl Vogel. Published 2009. $40.00* by Ian Hickman. 4th edition 2007 $61.00* A guide to RF design for engineers, technicians, students and enthusiasts. Covers key topics in RF: analog design principles, transmission lines, couplers, transformers, amplifiers, oscillators, modulation, transmitters and receivers, propagation and antennas. 279 pages in paperback. Alternative fuel expert Carl Vogel gives you a hands-on guide with the latest technical information and easy-to-follow instructions for building a two-wheeled electric vehicle – from a streamlined scooter to a full-sized motorcycle. 384 pages in soft cover. *NOTE: ALL PRICES ARE PLUS P&P – AUSTRALIA ONLY: $10.00 per order; NZ – $AU12.00 PER BOOK; REST OF WORLD $AU18.00 PER BOOK To Place Your Order: INTERNET (24/7) PAYPAL (24/7) eMAIL (24/7) www.siliconchip. com.au/Shop/Books Use your PayPal account silicon<at>siliconchip.com.au silicon<at>siliconchip.com.au with order & credit card details FAX (24/7) MAIL (24/7) Your order and card details to Your order to PO Box 139 Collaroy NSW 2097 (02) 9939 2648 with all details PHONE – (9-5, Mon-Fri) Call (02) 9939 3295 with with order & credit card details You can also order and pay for books by cheque/money order (Mail Only). Make cheques payable to Silicon Chip Publications. ALL TITLES SUBJECT TO AVAILABILITY. PRICES VALID FOR MONTH OF MAGAZINE ISSUE ONLY. ALL PRICES INCLUDE GST ALL S ILICON C HIP SUBSCRIBERS – PRINT, OR BOTH – AUTOMATICALLY QUALIFY FOR A REFERENCE $ave 10%ONLINE DISCOUNT ON ALL BOOK OR PARTSHOP PURCHASES. CHIP BOOKSHOP 10% (Does not apply to subscriptions) SILICON For the latest titles and information, please refer to our website books page: www.siliconchip.com.au/Shop/Books PIC MICROCONTROLLERS: know it all SELF ON AUDIO Multiple authors $85.00 The best of subjects Newnes authors have written over the past few years, combined in a one-stop maxi reference. Covers introduction to PICs and their programming in Assembly, PICBASIC, MBASIC & C. 900+ pages. PROGRAMMING and CUSTOMIZING THE PICAXE By David Lincoln (2nd Ed, 2011) $65.00* A great aid when wrestling with applications for the PICAXE See series of microcontrollers, at beginner, intermediate and Review April advanced levels. Every electronics class, school and library should have a copy, along with anyone who works with PICAXEs. 300 pages in paperback. 2011 PIC IN PRACTICE by D W Smith. 2nd Edition - published 2006 $60.00* by Douglas Self 2nd Edition 2006 $69.00* A collection of 35 classic magazine articles offering a dependable methodology for designing audio power amplifiers to improve performance at every point without significantly increasing cost. Includes compressors/limiters, hybrid bipolar/FET amps, electronic switching and more. 467 pages in paperback. SMALL SIGNAL AUDIO DESIGN By Douglas Self – First Edition 2010 $95.00* The latest from the Guru of audio. Explains audio concepts in easy-to-understand language with plenty of examples and reasoning. Inspiration for audio designers, superb background for audio enthusiasts and especially where it comes to component peculiarities and limitations. Expensive? Yes. Value for money? YES! Highly recommended. 558 pages in paperback. Based on popular short courses on the PIC, for professionals, students and teachers. Can be used at a variety of levels. An ideal introduction to the world of microcontrollers. 255 pages in paperback. PIC MICROCONTROLLER – your personal introductory course By John Morton 3rd edition 2005. $60.00* A unique and practical guide to getting up and running with the PIC. It assumes no knowledge of microcontrollers – ideal introduction for students, teachers, technicians and electronics enthusiasts. Revised 3rd edition focuses entirely on re-programmable flash PICs such as 16F54, 16F84 12F508 and 12F675. 226 pages in paperback. AUDIO POWER AMPLIFIER DESIGN HANDBOOK by Douglas Self – 5th Edition 2009 $85.00* "The Bible" on audio power amplifiers. Many revisions and updates to the previous edition and now has an extra three chapters covering Class XD, Power Amp Input Systems and Input Processing and Auxiliarly Subsystems. Not cheap and not a book for the beginner but if you want the best reference on Audio Power Amps, you want this one! 463 pages in paperback. DVD PLAYERS AND DRIVES by K.F. Ibrahim. Published 2003. $71.00* OP AMPS FOR EVERYONE By Bruce Carter – 4th Edition 2013 $83.00* This is the bible for anyone designing op amp circuits and you don't have to be an engineer to get the most out of it. It is written in simple language but gives lots of in-depth info, bridging the gap between the theoretical and the practical. 281 pages, A guide to DVD technology and applications, with particular focus on design issues and pitfalls, maintenance and repair. Ideal for engineers, technicians, students of consumer electronics and sales and installation staff. 319 pages in paperback. by Sanjaya Maniktala, Published April 2012. $83.00 Thoroughly revised! The most comprehensive study available of theoretical and practical aspects of controlling and measuring EMI in switching power supplies. Subtitled Exploring the PIC32, a Microchip insider tells all on this powerful PIC! Focuses on examples and exercises that show how to solve common, real-world design problems quickly. Includes handy checklists. FREE CD-ROM includes source code in C, the Microchip C30 compiler, and MPLAB SIM. 400 pages paperback. By Garry Cratt – Latest (7th) Edition 2008 $49.00 Written in Australia, for Australian conditions by one of Australia's foremost satellite TV experts. If there is anything you wanted to know about setting up a satellite TV system, (including what you can't do!) it's sure to be covered in this 176-page paperback book. See Review Feb 2004 SWITCHING POWER SUPPLIES A-Z PROGRAMMING 32-bit MICROCONTROLLERS IN C By Luci di Jasio (2008) $79.00* PRACTICAL GUIDE TO SATELLITE TV See Review March 2010 ELECTRIC MOTORS AND DRIVES By Austin Hughes & Bill Drury - 4th edition 2013 $59.00* This is a very easy to read book with very little mathematics or formulas. It covers the basics of all the main motor types, DC permanent magnet and wound field, AC induction and steppers and gives a very good description of how speed control circuits work with these motors. Soft covers, 444 pages. NEWNES GUIDE TO TV & VIDEO TECHNOLOGY By KF Ibrahim 4th Edition (Published 2007) $49.00 It's back! Provides a full and comprehensive coverage of video and television technology including HDTV and DVD. Starts with fundamentals so is ideal for students but covers in-depth technologies such as Blu-ray, DLP, Digital TV, etc so is also perfect for engineers. 600+ pages in paperback. RF CIRCUIT DESIGN by Chris Bowick, Second Edition, 2008. $63.00* The classic RF circuit design book. RF circuit design is now more important that ever in the wireless world. In most of the wireless devices that we use there is an RF component – this book tells how to design and integrate in a very practical fashion. 244 pages in paperback. AC MACHINES By Jim Lowe Published 2006 $66.00* Applicable to Australian trades-level courses including NE10 AC Machines, NE12 Synchronous Machines and the AC part of NE30 Electric Motor Control and Protection. Covering polyphase induction motors, singlephase motors, synchronous machines and polyphase motor starting. 160 pages in paperback. PRACTICAL VARIABLE SPEED DRIVES & POWER ELECTRONICS Se e by Malcolm Barnes. 1st Ed, Feb 2003. $73.00* Review An essential reference for engineers and anyone who wishes to design or use variable speed drives for induction motors. 286 pages in soft cover. Feb 2003 BUILD YOUR OWN ELECTRIC MOTORCYCLE PRACTICAL RF HANDBOOK by Carl Vogel. Published 2009. $40.00* by Ian Hickman. 4th edition 2007 $61.00* A guide to RF design for engineers, technicians, students and enthusiasts. Covers key topics in RF: analog design principles, transmission lines, couplers, transformers, amplifiers, oscillators, modulation, transmitters and receivers, propagation and antennas. 279 pages in paperback. Alternative fuel expert Carl Vogel gives you a hands-on guide with the latest technical information and easy-to-follow instructions for building a two-wheeled electric vehicle – from a streamlined scooter to a full-sized motorcycle. 384 pages in soft cover. *NOTE: ALL PRICES ARE PLUS P&P – AUSTRALIA ONLY: $10.00 per order; NZ – $AU12.00 PER BOOK; REST OF WORLD $AU18.00 PER BOOK To Place Your Order: INTERNET (24/7) PAYPAL (24/7) eMAIL (24/7) www.siliconchip. com.au/Shop/Books Use your PayPal account silicon<at>siliconchip.com.au silicon<at>siliconchip.com.au with order & credit card details FAX (24/7) MAIL (24/7) Your order and card details to Your order to PO Box 139 Collaroy NSW 2097 (02) 9939 2648 with all details PHONE – (9-5, Mon-Fri) Call (02) 9939 3295 with with order & credit card details You can also order and pay for books by cheque/money order (Mail Only). Make cheques payable to Silicon Chip Publications. ALL TITLES SUBJECT TO AVAILABILITY. PRICES VALID FOR MONTH OF MAGAZINE ISSUE ONLY. ALL PRICES INCLUDE GST 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; or send an email to silchip<at>siliconchip.com.au USB interface for PICs I would like to know a good starting point for interfacing a PIC-based project to a USB port? I understand how to do the serial port with a PIC as there are only a few lines and the protocol isn’t too tricky. Is there some snazzy chip that will do most of the protocol with a little bit of set-up from the PIC? (M. S., via email). • If all you need is a high-speed USB serial connection, the FT245BM and FT232BM devices from FTDI are the way to go. Check out their web site at www.ftdichip.com for more information. To make life even easier, these chips are available mounted on small plug-in modules that include all the necessary support logic, including the USB socket. You’ll find examples at www.elexol.com.au/USB_Modules and www.dontronics.com, who also stock the FDTI chips. If your needs are more specific, then Microchip offer the PIC16C745 & PIC16C765 with in-built USB ports. Alternatively, you could opt to interface your micro to one of many singlechip USB peripherals. A good place to start looking is www.beyondlogic.org Headlight as WiFi reflector I have a question regarding the article about “WiFry: Cooking Up 2.4 GHz Antennas” in the September 2004 issue. You say to use a parabolic shaped cooking scoop. Could a car headlight, with the glass removed do the same job? I’m pretty sure they are the correct shape and you could just replace the globe with the USB “dongle” and that would be it. I’m not sure if the reflective material in the headlight is enough but I guess it could be lined with foil? (D. L., Rye, Vic). • Provided the headlamp reflector is circular, it is a fair bet that it will be a paraboloid and therefore suitable for a WiFi antenna. The headlight metallisation should also work as a satisfactory reflector at 2.4GHz. On the other hand, most irregularly shaped headlight reflectors result in asymmetric light beams so they might not work as well with WiFi. Transformer for 6-channel amplifier I wish to build six 50W amplifier modules (SILICON CHIP, January & February 2003) for use in a home theatre system. These would be coupled with the 6-channel volume controller from the March & April 2002 issues. I am looking to build only one power supply for the six modules but the question arises, what capacity should my power transformer be? (W. N., Kurrajong, NSW). • You need a single transformer with a rating of at least 300VA. Unfortunately, the closest readily available transformer is the Altronics M-5530 300V 30V-0-30V. This could be reduced by RFID module: installation security concerns I have recently purchased the RFID module (SILICON CHIP, June 2003) and have successfully assembled and tested it. This is an excellent device, with many possible uses and was easy to construct and use. However, there are areas where it may be improved. First, the Reader Module could be closer to the outer panel (of whatever container is used) to maximise the operational range. At present, this is limited by the height of the output connectors. Second, in the case of an external installation, the security of the door strike function is considerably reduced by the exposure of the connector terminals. It would be a simple matter for anyone who is “tech savvy” and attempting entry 106  Silicon Chip to jumper terminals until the strike was activated. The fact that an alarm is triggered (if present) may not deter a serious attempt. The time allocated for door opening is about five seconds, which seems too short. It could be doubled to about 10 seconds without decreasing security very much. In my situation I only need the door strike function, but the unit needs to be installed externally. I intend removing the connectors and hard-wiring the outputs to inline insulated bullet connectors, which will connect to the external cabling behind the PC board. The Reader Module will be placed as close as possible to the outer panel by lowering the higher components. The initialising can be done pre-installation (on the bench). (K. M., via email). • We can’t see how security of the door strike is reduced by the exposure of the connector terminals. Even if the module was completely encapsulated, the wiring would still be open to tampering. The door strike “on” time is indeed set to five seconds. If you are knowledgeable about AVR microcontrollers and have access to a programmer, you can increase this time by altering the relevant parameter in the source code (RFID.ASM) and reassembling it. Look under the heading “CONSTANTS”. There you’ll find a line that reads: .equ LOCK_ON_TIME =10 The maximum possible “on” time is 16 seconds – ie, change 10 to 32. siliconchip.com.au using a 12V 2A transformer (Altronics M-256L) in auto-transformer reduce mode, to reduce the input voltage to the 300VA transformer. The method is explained in this month’s Circuit Notebook item on page 86. Alternatively, you could get one custom wound to 28V-0-28V from Harbuch Electronics, Phone (02) 9476 5854. Reconnecting an LCD to a PC board I have a talking clock radio that I rather like. Unfortunately, when I recently dismantled it to clean the switch contacts, the LCD detached itself from the circuit board and the attaching rubber strip of microconductors. This has caused me great distress considering how I will repair the connection. Is my only solution to get out the microscope and some conductive epoxy glue and try to repair it? Or am I able to purchase a replacement LCD mounted on a board that I can solder? (D. V., Newcastle, NSW). • You should be able to sandwich the elastomeric strip back between the PC board and the LCD and it should all go again. Controller for 10-channel remote I have brought and made up a 10-channel IR remote receiver kit from the February 2002 issue. I called Jaycar to get a kit to build a controller for it but they said they don’t have one. I would like to know if there is such a kit or the wiring diagram, etc. (G. M., Moura, Qld). • There is no kit for the controller. As outlined in the article, the circuit is designed to work with just about any pre-programmed remote that can control a satellite receiver. Have another look at the article. Class-H amplifiers switch supply rails It has come to my attention that some audio push/pull amplifiers have an extra switching transistor next to the main output transistors. Now having built a few amplifiers and studied electronics, I simply do not know what this extra transistor does. After looking at the old ETI-480 100W amplifier and a couple of other different amplifier siliconchip.com.au Extending a video monitor connection I wish to locate my computer screen an increased distance from the computer chassis. The required cable length is of the order of seven to eight metres. Can the average video card drive the signals this far? If not, can multiplexers/repeaters be used for the faster signals; ie, the R, G and B lines. Also, what type of cable would be required and are there any other issues involved with the increased distance? Alternatively, can the keyboard and mouse be extended by same distance? (E. R., Rye, Vic). • We’re not aware of the maximum cable length for such a connection but believe that it would vary con- modules, I cannot see how a switching transistor could possibly be used. Is it a different way of biasing the output transistors? • You are probably referring to ClassH amplifiers (originally developed by Hitachi) which switch the output stages to higher supply rails to enable much higher short-term power. Have a look at the Mighty Midget power amplifier in the March 2002 issue. This used class-H. Courtesy light delay for cars I have built and tested the Courtesy Light Delay kit as described in the June 2004 edition of SILICON CHIP. I have installed it into my 1989 Mitsubishi Magna Station Sedan (12V, negative earth). This model is fitted with a small light on the dashboard to show when the doors have not been properly closed. The kit passes all tests when the motor is off; ie, the interior lights switch off after a delay of about 35 seconds or when the car lights are activated. My problem is that after the delay period upon entering the car, the interior lights then come on and dim to a lesser degree continuously while the motor is running and I am driving. Switching on the parking lights of course solves the problem. When the car is parked and the motor is off, all is OK. I have disconnected the tail-light siderably from manufacturer to manufacturer. We’d suggest initially trying the hookup using one or two good quality monitor extension cables (available from most computer resellers). If the results are unsatisfactory, then you have a couple of options. You could purchase a purposebuilt SVGA video extender, such as the “Belkin OmniView”. These are available from various computer resellers in Australia. For a do-it-yourself solution, check out the “Video & Pulse Distribution Amplifier” described in the December 1997 edition of “Electronics Australia”. connections to the kit but the problem is still there. By disconnecting all four wires to the kit the interior lights work perfectly, as was always the case. This has me confused and I would greatly appreciate any help you can offer. (R. C., via email). • The circuit should not be triggered while the door switches are open. Capacitor C1 needs to be discharged fully via a closed door switch before the circuit can be triggered when the switch opens. To solve your problem, you could connect the “to tail lights” terminals to the ignition supply. In this way, the courtesy lights would be held off via the optocoupler pulling the gate of Q1 to the source terminal. Switching whine from speed controller I am using a 12V Motor Speed Control, as described in the June 1997 issue of SILICON CHIP, on a vehicle windscreen wiper motor. I get a high pitched noise from the motor (and others) when power is supplied through the control unit. This does not occur if 12V power is supplied direct to the motor. Any ideas on what is causing the noise and how to get rid of it? (G. O., via email). • All switch-mode speed controls cause motor whine. If your car has electric windows, you will probably hear some whine just as the motors November 2004  107 Playmaster 300W amplifier hums & thumps I’m hoping someone can shed some light on a couple of problems I have with a power amplifier for a 500W subwoofer. It’s from the April 1995 issue of “Electronics Australia”. Ever since I built it six years ago, it has had a weird quirk: about one minute after switching power off, the attached speaker starts thumping. It starts off slowly (around two thumps per second) and loudly (about 10mm speaker excursion) and over the course of five minutes the thumping speeds up (maybe six thumps per second) and dies off. Somewhere in the middle, the thumping seems to switch to double-time. The amplifier also has a “clipping” LED on the front panel, which is meant to show if you’re driving the amplifier too hard. During its thumping routine, the LED flashes in time with the thumping. Yes, I have checked for animals and small people trapped in the box! The other quirk may be related – loud humming. Not when a source come to a stop. The noise is caused by the high-frequency switching signal which applies DC to the motor. You may be able to reduce the noise by altering the frequency a little. Try replacing the 10kΩ resistor at pin 6 of IC1 with a 20kΩ trimpot in series with a 4.7kΩ resistor. Then adjust the trimpot for the least noise from the motor. Studio 350 fried resistors I have built a Studio 350 amplifier module (SILICON CHIP, January & February 2004) and upon powering it up, I found that the voltage readings across the speaker terminals were nearly equal to the output voltage of the power supply. I have checked all the board parts and connections three times and can find no faults with the construction. Later, as I was trying to adjust the voltages to zero as described, the resistors in the area of the audio input (Q2, 108  Silicon Chip is plugged in but only when you touch the signal terminal of the input RCA lead with a finger. I don’t know what frequency the hum is (no oscilloscope) but it sounds low, like a truck horn. It might be 50Hz but I don’t really know what 50Hz sounds like. The humming is quieter if you touch the shielding of the RCA lead with the same finger or if you touch the amplifier case with your other hand. Is this expected/normal? As I said, it only happens under these conditions. The amplifier operates noiselessly and as expected when plugged into my preamp and playing music. Thanks very much for any insight! (C. C., via email). • The hum is probably due to instability in the Mosfet output stages; they’re probably oscillating at 100MHz or more (you can check that with an FM radio). Check all the Mosfet gate capacitors. The slow oscillation could be related to the above; ie, motorboating. Perhaps some of the bypass capacitors on the supply rails are open-circuit. Q3) fried, damaging the board surface somewhat. Can you suggest what to do next? (P. C., via email). • Our guess is that you have swapped a pair of transistors or you have an open-circuit solder connection somewhere. Replace the fried resistors and power up the board again, with the resistors across the fuseholders, and check each transistor for a base-emitter voltage of about 0.7V. An incorrect reading indicates a fault in the transistor or its associated components. Dr Video has dark rectangle I have just finished building the Dr Video kit (SILICON CHIP, June 2004) and I have a dark rectangle block in the top lefthand corner of the screen. Any ideas? (S. J., via email). • It sounds as if your vertical blanking pulse circuit (around IC6b, IC6c and IC5b) is generating a pulse longer than the correct 1.1ms. This is probably due to within-tolerance compo- nent variations, so we suggest you try replacing the 8.2nF capacitor with one of 6.8nF or 5.6nF. This should remove the “dark rectangle”. Volume control for valve preamp I have a question regarding the Valve Preamp For Hifi (SILICON CHIP, February 2004). In the article you place the volume pot after the preamp. I was wondering if it could be placed before the preamp and would this change performance in any way? (R. D., Doncaster, Vic). • There are arguments for and against putting the volume control in front of a preamp. Putting it in front means you reduce the chance of overload but it also means the signal to noise ratio of the final signal may not be as good. Energy Meter can measure to 15A Why did you limit your Energy Meter (SILICON CHIP, July & August 2004) to only 10A? I want to measure my air conditioner. How could I modify your design to go to (at least) 15A, please? (P. B, Turramurra, NSW). • The Energy Meter was limited to 10A because this is the maximum rating of a general purpose mains outlet (GPO). You can still use the meter to measure 15A if your GPO, the fuse and power cords are rated for this. It would be wise to bypass the relay for 15A measurements, to prevent damaging the relay contacts. Otherwise, the meter can operate at 15A (3600W) without any software or hardware changes. Micromitter’s filter is faulty The last time I was in Australia, I purchased an FM Micromitter kit (SILICON CHIP, December 2002) in Brisbane. I have now built the kit and have a problem – there is very little RF output. I looked at the Rohm website and found an Application Circuit for the BH1417F chip employed in the kit. It shows a 1nF DC blocking capacitor between the chip output and the GFWB3 filter. The data indicates that there should be typically (Vcc - 1.9) volts on pin 11. In my version there was no voltage on pin 11 because pin 1 of the filter has siliconchip.com.au DC continuity to ground. I have fitted a 1nF capacitor and the unit now works correctly, with about 3.1V on pin 11. However, I wondered afterwards if the filter input is actually pin 3, which does not have DC continuity to ground and perhaps I could have just reversed the filter on the board. Have you encountered this problem before. (D. D., Cheltenham Spa, UK). • There should be no need to have a DC blocking capacitor before the filter as the filter is capacitive. Perhaps your filter has a fault, causing DC to flow to ground. No secret code for LED marking Like many readers I have been experimenting with a variety of LEDs. Given the state of my workbench, I now have quite a random collection – all unmarked! Is there any way of finding out LED characteristics from scratch? And is there any logical reason why manufacturers refuse to mark LEDs with type numbers (or have I missed some secret inscription)? After all, if transistors were unmarked where would we be? (J. B., Dalton, NSW • Short of testing all your LEDs with a low-voltage DC source, there is no way of knowing their characteristics. And if you can find the “secret way” of LED marking, please let us know and we will pass it on to the world at large! 240V halogens still have UV output I know you never were too keen on 12V down-lighting with inefficient hot transformers but have you seen the new 240V halogens that K-mart and other chains now sell? They are glass encased, so no UV radiation and are rated at 50W. I am wondering if these kinds of halogens are OK to use with normal light dimmers. Mine dim OK but I am worried if I am reducing the life of the halogens that may need to run hot like other halogens. • 240V halogens have been available for some time but we are not aware that the types you refer to have zero ultra-violet output. Given the very high filament temperatures, that seems highly unlikely. In any case, using a dimmer with any halogen has the effect of reducing their efficiency as well as reducing life. Also 240V halogens tend not to last as long as 12V types because their much higher resistance filament is nowhere near as rugged. Fridge causes TV interference I have a new GE fridge which creates TV interference. There are waves across the screen which vary depending on the fridge motor speed. How can this be fixed? (B. C., via email). • First, you must determine the mechanism of the interference. Is the interference visible on all channels? If so, it is possible that the motor’s magnetic field is directly affecting the picture tube. Is the fridge close to the TV? If so, the cure is to move the TV away from the fridge. On the other hand, if the interference is present only on one channel then the source is possibly some electronic circuit within the fridge. If so, it may well be a fault since consumer Notes & Errata Programmable Robot, September 2004: there is an error in the circuit diagram of Fig.1 on page 65, concerning the programming cable socket (CON1). Earth should go to the tip of the 3.5mm socket, while the junction of the 22kΩ & 10kΩ resistors goes to the ring. The sleeve connection is correct, as is the PC board layout on page 66. Garage Door Controller, October 2004: some readers want to use smaller motors with this kit and Oatley Electronics has advised that if R22 and R17 are changed to 82kΩ, the current is adjustable from 0-4A. Initially, set trimpots VR1 and VR2 to their centre positions, as the circuit may prematurely trip at the most sensitive settings. Video Formats: Why Bother?, August 2004: a number of readers have asked where the PAL DVD test disc mentioned in the article can be obtained. Sanity currently stock the disc, on the web at www. sanity.com.au or phone 1300 722 121. Ask for the “Digital Video Essentials” DVD. Universal Power Supply Board, August 1988: the 1000µF capacitor in Fig.8 (parts layout) is shown with reversed polarity. equipment is supposed to meet EMC standards. We would then make a complaint to the distributor, or in the SC first instance, to the retailer. 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. siliconchip.com.au November 2004  109 MARKET CENTRE Cash in your surplus gear. Advertise it here in Silicon Chip. CLASSIFIED ADVERTISING RATES Advertising rates for this page: Classified ads: $22.00 (incl. GST) for up to 20 words plus 66 cents for each additional word. Display ads: $36.00 (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. Alternatively, fax the details to (02) 9979 6503 or send an email to silchip<at>siliconchip.com.au 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______________ Phone:_____________ Fax:_____________ Email:__________________ 110  Silicon Chip FOR SALE Logbox and FieldLogger universal input dataloggers sPlan Windows electronic schematic software and Sprint Layout Windows PCB layout software are feature packed but low in price Labjack USB Data Acquisition Module features 8 12bit analog inputs, 20 digital I/O, 2 analog outputs and high speed counter. Free software, Labview driver and ActiveX component. DAS005 Parallel Port Data Acquisition Module features 8 12bit Analog inputs, 4 Digital I/Ps & 4 Digital O/Ps. Free windows software and source code. Pixel Programmable Controller with 4 analog inputs, 8 digital inputs and 8 relay outputs. Can use a 28A or 28X Picaxe. Programmed in basic or Flow chart. 2, 4 & 8 Relay Modules suitable for TTL and Open Collector Outputs. Programmers for Atmel and PIC microcontrollers. Stepper Motor and Servo Motor controller kits. Switch Mode and Linear Power Supplies and DC-DC converters. Full details and credit card ordering available at www.oceancontrols.com.au RCS RADIO/DESIGN is at 41 Arlewis St, Chester Hill 2162, NSW Australia and has all the published PC boards from SC, EA, ETI, HE, AEM & others. Ph (02) 9738 0330. sales<at>rcsradio. com.au, www.rcsradio.com.au 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°. 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 siliconchip.com.au ELNEC IC PROGRAMMERS Universal and specialised models High quality Realistic prices Large range of adaptors Free regular software updates Windows 95/98/Me/NT/2k/XP GRANTRONICS PTY LTD PO Box 275, Wentworthville. 2145. Ph: 02 9896 7150 New New New Foam surrounds,voice coils,cones and more Original parts for Dynaudio,Tannoy and others Expert speaker repairs – 20 years experience Australian agents for products Trade welcome – email for your user ID Phone (03) 9647 7000 Mark22-SM Slimline Mini FM R/C Receiver speakerbits.com.au www.grantronics.com.au TAIG MACHINERY Micro Mini Lathes and Mills From $489.00 • • • • • 6 Channels 10kHz frequency separation Size: 55 x 23 x 20mm Weight: 25gm Modular Construction Price: $A129.50 with crystal Electronics Stepper motors: 200 oz in $89.00, 330 oz in $110.00 Digital verniers: 150mm $55.00, 200mm $65.00 59 Gilmore Crescent (02) 6281 5660 Garran ACT 2605 0412269707 NIXIE TUBES, including IN-18 with 40mm digits and IN-17 with 8mm digits. Also see my nixie clock kit, just $140 including tubes! 5mm superbright LEDs from 35 cents each. New 12mm superbright LEDs! Huge 4-inch, 4 digit green LED clock displays just $32. Other great stuff including Russian components. www.ledsales.com.au DIRECTIONS to find information about semiconductors, projects, valves and more, referenced in Silicon Chip 90-04, EA 86-94, most TE, some ETI. Easyfind groupings on CD-ROM. Requirements: PC or MAC capable of opening web pages from CD. AUD$15.00 includes postage Australia wide. Ian Mullins, 174 Pinnacle Drive, Condon, 4815. PIC/AXE PROJECT PCBs for home automation and robotics, POWERMATE energy meter. Your home DVD, YH Technical Manual, Nixie Clock. All OZ designs. info<at>techbits.com.au, www. techbits.com.au PHILIPS N1700 VCR: have several to dispose of with spares and tapes. Adelaide, SA. Phone (08) 8255 0025 BUY FROM HONG KONG, PAY IN OZ. Get many common components direct from Hong Kong but pay in Oz. www. kitsrus.com/bits.html siliconchip.com.au PATENT LICENCES USA, Aust. for sale. Electronic machine vibration tester. Manufacture to untapped market. Phone AH (03) 5979 8303. PO Box 580, Riverwood, NSW 2210. Ph/Fax (02) 9533 3517 email: youngbob<at>silvertone.com.au Website: www.silvertone.com.au 2.4 GHz WiFi Antennas  PCBs MADE, ONE OR MANY. Any format, hobbyists welcome. Sesame Elec­tronics (02) 9593 1025. sesame777<at>optusnet.com.au http://sesame_elec.tripod.com S-Video . . . Video . . . Audio . . . VGA distribution amps, splitters, standards converters, tbc’s, switchers, cables, etc, & price list: www.questronix.com.au ImageCraft C Compilers: 32-bit Windows IDE and compiler. For AVR, 68HC­08, 68HC11, 68HC12, 68HC16. from $330.00 Atmel Flash CPU Programmer: Handles the 89Cx051, 89C5x, 89Sxx in both DIP and PLCC44 and some AVR’s, most 8-pin EEPROMS. Includes socket for serial ISP cable. $220, $11 p&p. SOIC adaptors: 20 pin $132.00, 14 pin $126.50, 8 pin $121.00. Full details on web site. Credit cards accepted. GRANTRONICS PTY LTD, PO Box 275, Wentworthville 2145. (02) 9896 7150 or http://www.grantronics.com.au KITS KITS AND MORE KITS! Check ’em out at www.ozitronics.com           Web: Email: Tel: Fax: Also Available Panel Antennas Ceiling Antennas Low Loss 50 ohm cable Connectors Pigtails Access Points Masts Amplifiers Power over Ethernet External Enclosures www.freenet-antennas.com sales<at>freenet-antennas.com +61 (8) 9319 3275 +61 (8) 9319 1720 STOCK REDUCTION SALE: Every Friday 12pm to 5pm. Electronic components, switches, LEDs, displays, enclosures, connectors, crystals, relays, neons and many more. At Switches Plus Components, Unit 1 - 2 Sibthorpe Street, Braeside, Victoria. Phone (03) 9587 4044. November 2004  111 Do You Eat, Breathe and Sleep TECHNOLOGY? Opportunities for full-time and part-time positions all over Australia & New Zealand Jaycar Electronics is a rapidly growing, Australian owned, international retailer with more than 39 stores in Australia and New Zealand. Our aggressive expansion programme has resulted in the need for dedicated individuals to join our team to assist us in achieving our goals. We pride ourselves on the technical knowledge of our staff. Do you think that the following statements describe you? Please put a tick in the boxes that do: Knowledge of electronics, particularly at component level. Assemble projects or kits yourself for car, computer, audio, etc. Have empathy with others who have the same interest as you. May have worked in some retail already (not obligatory). Have energy, enthusiasm and a personality that enjoys helping people. Appreciates an opportunity for future advancement. Have an eye for detail. Why not do something you love and get paid for it? Please write or email us with your details, along with your C.V. and any qualifications you may have. We pay a competitive salary, sales commissions and have great benefits like a liberal staff purchase policy. Advertising Index Alternative Technology Assoc........7 Altronics........................ loose insert Send to: Retail Operations Manager - Jaycar Electronics Pty Ltd P.O. Box 6424 Silverwater NSW 1811 Email: jobs<at>jaycar.com.au Av-Comm...................................110 Jaycar Electronics is an equal opportunity employer and actively promotes staff from within the organisation. Eco Watch..................................112 Dick Smith Electronics........... 14-19 Elexol...........................................47 Evatco..........................................99 Grantronics.................................111 WEATHER STATIONS: windspeed & direction, inside temperature, outside temperature & windchill. Records highs & lows with time and date as they occur. 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 catalog and price list. Eco Watch phone: (03) 9761 7040; fax: (03) 9761 7050; Unit 5, 17 Southfork Drive, Kilsyth, Vic. 3137. ABN 63 006 399 480. WANTED WANTED TO BUY: original Philips 12inch bass speaker. It’s used in the ETI 4000 speaker kit. (08) 8087 2592. WANTED: CIRCUIT DIAGRAM for AWA Pilotphone IX marine radio, plus display in good order. Also, control head for Philips FM900 series radio. Phone (03) 6427 9340. Harbuch Electronics.....................87 Hy-Q International........................89 Instant PCBs..............................112 Jaycar ..................49-64,89,112,IFC WANTED: EARLY HIFI’S, AMPLIFIERS, Speakers, Turntables, Valves, Books, Quad, Leak, Pye, Lowther, Ortofon, SME, Western Electric, Altec, Marantz, McIntosh, Goodmans, Wharfedale, Tannoy, radio and wireless. Collector/Hobbyist will pay cash. (02) 9440 1267. johnmurt<at>highprofile. com.au KIT ASSEMBLY NEVILLE WALKER KIT ASSEMBLY & REPAIR: • Australia wide service • Small production runs • Specialist “one-off” applications Phone Neville Walker (07) 3857 2752 Email: flashdog<at>optusnet.com.au JED Microprocessors................5,89 Microgram Computers....................3 MicroZed Computers...............45,89 Oatley Electronics........................27 Ozitronics..............................45,111 Prime Electronics.........................43 Quest Electronics..................89,111 RCS Radio.................................110 RF Probes....................................99 Silicon Chip Back Issues.... 102-103 Silicon Chip Binders.....................47 Silicon Chip Bookshop....... 104-105 SC Car Projects Book................101 NOW AVAILABLE FROM Silicon Chip Subscriptions...........65 Silvertone Electronics................111 Speakerbits................................111 www.siliconchip.com.au Taig Machinery...........................111 Telelink Communications....89,OBC VAF Australia..............................IBC Project Reprints – Limited Back Issues –Limited One-Shots If you’re looking for a project from ELECTRONICS AUSTRALIA, you’ll find it at SILICON CHIP! We can now offer reprints of all projects which have appeared in Electronics Australia, EAT, Electronics Today, ETI or Radio, TV & Hobbies. First search the EA website indexes for the project you want and then call, fax or email us with the details and your credit card details. Reprint cost is $8.80 per article (ie, 2-part projects cost $17.60). SILICON CHIP subscribers receive a 10% discount. We also have limited numbers of EA back issues and special publications. Call for details! visit www.siliconchip.com.au or www.electronicsaustralia.com.au 112  Silicon Chip WIA..............................................89 ____________________________ PC Boards Printed circuit boards for SILICON CHIP projects are made by: RCS Radio Pty Ltd. Phone (02) 9738 0330. Fax (02) 9738 0334. siliconchip.com.au Legendary VAF Speakers now even better *conditions apply Rolling Stone Magazine said “The ultimate in high fidelity performance with the best bass in the world” DVD Now said “They are the best speakers I have ever heard” Best Buys Home Theatre said “We have yet to hear a system that sounds as good” Now with a 30 day in home money back guarantee, 10 year manufacturer’s guarantee and up to $250 worth of cables and accessories at no extra charge. . . better hurry! After 30 years, still affordable and still directly shipped from VAF to you, anywhere on earth! FreeCall 1800 818 882 www.vaf.com.au