Fullscreen HTML5Med Res (??MB)HTML4

SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings.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.20, No.10; October 2007 SILICON CHIP www.siliconchip.com.au Features 10 DVD Players: How Good Are They For HiFi Audio? Dedicated audio CD players are now relatively expensive so what are the compromises in using a cheap DVD player instead? – by Mauro Grassi DVD Players: How Good Are They For HiFi? – Page 10. 18 Agilent DS05054A 4GS/s 500MHz Digital Scope Looking for a high-end digital scope? This new model from Agilent really has the goods – by Mauro Grassi Pro jects To Build 26 Oscar: Electronic Noughts & Crosses Game The first Oscar used 70 telephone relays & was as big as a fridge. The 2007 version uses a PIC micro and fits in a zippy box! – by Brian Healy 32 PICProbe: A Versatile Logic Probe This PIC-based logic probe fits inside a pen case and works down to 2.7V. Build it as your first surface-mount-device project – by Ross Purdy 40 Rolling Code Security System; Pt.1 Versatile IR unit is ideal for keyless entry and features an alarm system, two door-strike outputs and provision for up to 16 transmitters – by John Clarke 68 Simple Data-Logging Weather Station; Pt.2 Oscar: An Electronic Noughts & Crosses Game – Page 26. PIC-Based Logic Probe – Page 32. Second article has all the details on the mechanical construction, including the tipping rain bucket and the temperature sensor housing – by Glenn Pure 82 AM Loop Antenna & Amplifier Build it to improve your AM reception and to listen to long-distance AM stations you only dreamed existed – by Branko Justic & Ross Tester Rolling Code Security System – Page 40. Special Columns 63 Serviceman’s Log Fix it in the carpark! – by the TV Serviceman 92 Circuit Notebook (1) Bi-Directional Variable Speed Drive With Regenerative Braking; (2) Pea & Thimble Or 3-Card Trick; (3) Emergency Lights Controller; (4) Two Novel LED Flashers; (5) Adjustable Q For Subwoofer Equaliser 98 Vintage Radio Nazi Germany’s Peoples’ Radio (Volksempfaenger) – by Rodney Champness Departments   2   4   9 79 Publisher’s Letter Mailbag Order Form Product Showcase siliconchip.com.au 104 Ask Silicon Chip 107 Notes & errata 110 Market Centre AM Loop Antenna And Amplifier – Page 82. October 2007  1 SILICON CHIP www.siliconchip.com.au Publisher & Editor-in-Chief Leo Simpson, B.Bus., FAICD Production Manager Greg Swain, B.Sc.(Hons.) Technical Staff John Clarke, B.E.(Elec.) Ross Tester Jim Rowe, B.A., B.Sc, VK2ZLO Mauro Grassi, B.Sc.(Hons.) Photography Ross Tester Reader Services Ann Morris Advertising Enquiries Glyn Smith Phone (02) 9939 3295 Mobile 0431 792 293 glyn<at>siliconchip.com.au Regular Contributors Brendan Akhurst Rodney Champness, VK3UG Kevin Poulter 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: $89.50 per year in Australia. For overseas rates, see the subscription page in this issue. Editorial office: Unit 1, 234 Harbord Rd, Brookvale, NSW 2100. Postal address: PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 9939 3295. Fax (02) 9939 2648. E-mail: silicon<at>siliconchip.com.au ISSN 1030-2662 * Recommended and maximum price only. 2  Silicon Chip Publisher’s Letter Cheap DVD players are just that: cheap! If ever there was a great example of the march of technology rendering appliances cheaper, it has to be DVD players. Considering that it is not too many years ago that typical DVD players cost $1000 or more, today’s sub $50 price is incredible. Not only that but today’s cheap DVD players will play just about anything. Some of them would probably even play a wet beer coaster, provided they were round and fitted in the disk drawer. Well, maybe they’re not quite that capable but you get the idea. Just recently, the cheapest-ever DVD player was a Tevion brand unit from Aldi stores priced at just $39! No doubt, there are even cheaper examples available on eBay. The question which must be asked is: just how do they do it? It must mean that the factory price is incredibly low. And it is not just one factory in Asia that is doing this – there are thousands of factories right throughout Asia. Nor are these machines short on features. Not only will they play all sorts of disk formats, they usually also have a digital display, optical and digital outputs, Dolby 5.1 digital output and volume control via the infrared remote control. But when you open these machines up, there is not much inside their very light and often quite flimsy chassis. You have the plastic disk player itself, the switchmode power supply and a small PC board carrying one large VLSI chip and otherwise packed with surface-mount devices. If one of these machines fails, it will not be worth getting it repaired – it will go straight to the tip. Even machines which fail during warranty won’t be repaired. Such repairs would cost far more than the retail value of the machine. So what is the downside? Until recently, apart from the ever-growing heap of electronic junk going to the tip, we had not been aware of any downside. Then we became aware of the downside when I purchased that self-same Tevion machine to replace quite an old CD player that I had in my study. When I hooked it up to my equally venerable Harman Kardon AM/FM stereo receiver, I noted that the player sounded OK but certainly not like a really good CD player. But when I switched across to the AM broadcast band while still leaving the DVD player on, I noticed that the entire AM broadcast band was blotted out. Hmm. There must be quite a lot of radiated hash, I thought. So I picked up a portable radio and yes, there was a great deal of interference. That was bad enough but then I switched across to FM and was staggered to find that the FM reception was blotted out as well. In normal circumstances, blotting out FM reception is no easy feat. If you wanted to deliberately blot out all FM reception in a limited area, you would have to put out a very strong signal in order to overcome the “capture effect” of a standard FM tuner. But now we have a simple answer – just use a cheap DVD player and amplify the RF rubbish radiated by its audio outputs. This also makes nonsense of any EMC checks that may have been made on this player for C-tick or any other compliance testing The rest of this story starts on page 10 of this issue and while our survey of DVD players is very limited, it does clearly demonstrate that you still get what you pay for. In other words, if you buy a cheap DVD player, don’t expect it to give you hifi quality sound. The same caution might also apply to the video performance of these cheap players although we are inclined to think that since they all tend to use a standard jungle chip inside them, they probably all give quite reasonable performance in that regard. However, we would not suggest that you spend a lot of money on an expensive plasma or LCD TV or an LCD video projector and then team it up with a cheap DVD player. That would be a waste of money! Leo Simpson siliconchip.com.au For all those innovative, unique, interesting, hard to find products Device Extenders Description 11683-7 3627-7 3628-7 3441-7 11625-7 11662-7 11812-7 USB Extender to 60m over LAN cable DVI Extender to 15m over LAN Cable DVI Extender to 45m over LAN Cable VGA Extender to 130m over LAN Cable Console Extender to 80m over Standard Cables Console Extender to 150m over LAN Cable Wireless TV/Video Sharer to 100m (2.4Ghz) Price Cat 3441 $99 $169 $269 $399 $179 $399 $79 Cat. No. Price 1008265-7 Wireless VGA Adapter (802.11g based) 17115-7 LGA775 Motherboard with ISA Slots 15156-7 USB to VGA Adapter USB Converters Cat. No. 2729-7 2685-7 2920-7 2929-7 2853-7 2907-7 23025-7 Description USB to Parallel – DB25 USB to Parallel - Centronics USB to Serial (RS232) 1 Port USB to Serial (RS232) 8 Port USB to RS422/485 1 Port USB to RS422/485 4 Port USB to 5.1 Sound Adapter PC Switches Cat. No. 11667-7 11668-7 11658-7 11670-7 11659-7 11657-7 12049-7 Description Cat 2685 $59 $35 $59 $459 $249 $560 $45 Cat 2929 Cat 23025 Cat 11667 Price Console Share Switch – 2 Users share 1 PC KVM Switch 2 Port with Cables – PS/2 KVM Switch 2 Port with Cables & Audio - USB KVM Switch 4 Port with Cables & Audio – PS/2 KVM Switch 4 Port with Cables & Audio - USB Cat 11668 KVM Switch 16 Port – PS/2 USB Manual Switch – 4 Port Cat 11657 $139 $75 $85 $110 $135 $799 $39 23055-7 23054-7 23003-7 23032-7 23002-7 23003-7 3438-7 Description HDMI 2 Port Switch with Remote Control Cat 23032 HDMI 4 Port Switch with Remote Control AV Switch 3 Port with S-VHS/RCA & RCA/Optical AV HD Switch 3 Port with Component & RCA/Optical Optical Audio Switch – 4 inputs & 2 outputs Optical Audio Switch – 3 inputs & 1 output AV Switch RCA – 4 inputs & 2 outputs Cat 3438 9287-7 9521-7 9526-7 Description Price Cat 9287 Cordless Pen Mouse Cordless Pen Mouse with Laser Pointer Remote Control - Voice Activated & Programmable! 8551-7 9549-7 1008258-7 8751-7 12v DC Input ATX Power Supply 300W 24v DC Input ATX Power Supply 450W Handheld Trackball with Laser Pointer – Cordless Mini Keyboard with Integrated Touchpad 2459-7 2462-7 6988-7 6913-7 eSATA PCI Express (PCIe) 1 Port eSATA Card PCI 2 Port eSATA Card SATA 2.5” HD to eSATA & USB Combo Enclosure SATA 3.5” HD to eSATA & USB Combo Enclosure $319 $399 $139 $139 Cat 15156 1008319-7 SATA to eSATA Backplane – 2 Port 1008241-7 eSATA Cable 1m Price $115 $169 $89 $99 $118 $89 $89 3683-7 3692-7 2403-7 2402-7 2401-7 ExpressCards Digital TV Tuner Digital & Analogue Hybrid TV Tuner Firewire 1394A 2 Port Gigabit Ethernet eSATA 2 Port $50 $94 $65 $85 $18 $14.50 Cat 8751 USB Microscopes USB Microscope Basic USB Microscope with Microtouch USB Microscope with Microtouch Trigger USB Microscope PLUS with Measurement USB Microscope with Microtouch & Measure $129 $149 $389 $549 $649 $179 Cat 1008265 3626-7 3685-7 3686-7 3687-7 3688-7 AV Switches Cat. No. What’s New? Cat 11683 Cat. No. Cat 6913 $239 $269 $295 $359 $499 $149 $169 $129 $119 $119 Cat 3626 Not sure what product you need? Call us today for friendly advice! 1800 625 777 www.mgram.com.au Cat. No. 9514-7 9510-7 9493BLK-7 1008149-7 1008178-7 8264-7 5839BLK-7 9512BLK-7 5551-7 5751-7 9338-7 Gadgets Description Price POS Bundles Basic Point Of Sale Bundle Premium Point Of Sale Bundle Cat 8264 Barcode Scanners USB Barcode Scanner - CCD USB Barcode Scanner - Laser Bluetooth Cordless Barcode Scanner - CCD Assorted Hardware Magnetic Card Reader Track 1, 2 & 3 – PS/2 Thermal Receipt Printer - Parallel Cash Drawer – RJ12 (Connects to receipt printer) Mini Label Printer – 54mm Wide Zebra LP2844 Label Printer – 104mm Wide Cheque Reader – PS/2 Cat 1008178 $799 $999 $189 $359 $599 $139 $569 $179 $239 $659 $718 Cat. No. Description 3655-7 1168-7 3527-7 3102-7 2726-7 2737-7 6741-7 2874-7 2959-7 1248-7 2457-7 8933-7 15141-7 6885-7 USB EPROM Programmer Car PC 12v – 1Ghz 512Mb 80Gb WinXP USB 2.0 Analog TV Tuner & Video Capture VGA to Video Converter with VGA Pass-through PCMCIA 2 Port Serial Adapter PCMCIA to Parallel Adapter IDE to Compact Flash Adapter – Front Access Independent RAID Server – Dual IDE HD with Hot Swap Independent RAID Server – Dual SATA HD with Hot Swap Windows CE Based Terminal with Wyse Emulation PCIe to ExpressCard Adapter USB Macro Keypad – 20 Key Programmable USB Macro Stick – 16 Key Programmable USB to PCMCIA for Wireless Broadband Cards 32-bit Cat 6741 Cat 5751 Cat 2726 MicroGram Computers Unique IT Solutions Price Cat 2874 $499 $1659 $119 $149 Cat 1168 $269 $269 $99 $569 Cat 3527 $599 $699 $109 $299 Cat 3102 $199 $299 Cat 2457 Cat 1248 1800 625 777 ask<at>mgram.com.au www.mgram.com.au All prices subject to change without notice. For current pricing visit our website. Pictures are indicative only. SHORE AD/MGRM1007 Point of Sale ask<at>mgram.com.au MAILBAG Letters and emails should contain complete name, address and daytime phone number. Letters to the Editor are submitted on the condition that Silicon Chip Publications Pty Ltd may edit and has the right to reproduce in electronic form and communicate these letters. This also applies to submissions to “Ask SILICON CHIP” and “Circuit Notebook”. LM4562 distortion test method is flawed Your article on measuring distortion in the LM4562, published in the August 2007 issue, tries to validate a flawed test technique used by National Semiconductor. I recently debunked this in my online forum at: http://ska-audio.com/Forum/YaBB. pl?num=1185394996/0#0 I also detailed this back in 1992 through the letters column of Wireless World when Burr-Brown used much the same technique. It gives great marketable figures but it’s not good technique. Now NS have adopted it. The test uses a full unity gain CM signal then effectively divides it by 100 along with the feedback-affected circuit distortions. Do I have a better way? Well, the scaling method will work OK with inverting mode. Do a x-100 test and divide it for the x1 figure, which in this case will likely be very low. The x100 result could be compared with A different solar hot water system experience I was bemused to read the article in the August 2007 issue “How to Cut Your Greenhouse Emissions Part 2”; bemused because my experience with solar hot water is so different. I happen to live just inside the tropics in the light green-shaded area in the map on page 10, the 75-80% zone. Two years ago I had a solar hotwater system installed at home when the aged electric system gave up the ghost. I opted for a marginally larger capacity model than the minimum recommended, as the additional cost was less than 10% at the time. I also opted to move from offpeak electricity, with its minimum monthly charge, to standard tariff (costs more per kWh but no minimum charge) and only switch on the booster when needed. There’s 4  Silicon Chip the existing test result. If there is any difference it could be CM distortion but it would need to be in the same order of magnitude to show. In short, the dominant distortions in an op amp are common mode distortion, which doesn’t generally change greatly with level, and the loop distortion reduced by negative feedback. To use a technique that assesses total distortion in a x100 loop with a x1 common mode signal, and divides the result by 100 for a unity gain distortion result, devalues the CM distortion 100 times as it is already x1 as measured. Common mode distortion is often the baseline THD of op amps over much of the audio range when operated in non-inverting mode, the loop distortion falling with increasing feed­ back to just above the open loop pole frequency. Your measured figure of predominantly 2HD at 0.0025% could well be the x1 CM distortion not x-100 loop no reticulated gas supply here, so gas boosted wasn’t an option. Having now lived with solar hot water for two years, I can report on how often I’ve had to switch on the electric booster. The answer is once during winter in 2006 for two hours, and twice during winter 2007 for four hours total. We had only one lukewarm shower experience during those two years due to my not turning the booster on early enough. The only behavioural modification for the household, post solar, was evening rather than morning showers. Cold water washing was already the norm. Do I recommend solar hot water to friends and neighbours? Of course! And No, I don’t work in the plumbing or solar hot water industries. Ross Dannecker, Rockhampton, Qld. distortion. The test is invalid – but great for low figures! Greg Ball, Banksia Beach, Qld. Comment: Your letter has been thought provoking to say the least. We were not aware of your debunking. Did BurrBrown or National Semiconductor ever reply to your criticism? But triggered by your letter, try as we might, we cannot work out any way to measure or estimate CM distortion. The CMRR (common mode rejection ratio) of the LM4562 is -120dB which means that if the op amp has a closed loop gain of say, +20dB, the CM gain will be -100dB. Even if you then apply the maximum permissible CM signal of 20V P-P, the resulting output will only be 0.2mV P-P which is hardly enough to measure or estimate any likely CM distortion. Looking at it another way, if we assume that CM distortion is 10% (ie, really bad), then the CM distortion component of a THD measurement for an LM4562 op amp circuit with a gain of say +10dB, is going to be around -130dB or .00003%. Which is in the ball-park of our measurements! Incidentally, we are not saying that your debunking of the distortion measuring method is wrong but in the case of the LM4562, the difference may simply be academic. Nor do we understand, if the method is inappropriate for a non-inverting op amp, how it can be correct for the inverting op amp. Surely the same “common mode failure” would apply? LEDs must surely replace incandescent lamps Like many people, I am not impressed with the half-hearted approach of our Federal government to persuade us that it would be a good idea to substitute CFLs for incandescents in our homes. CFLs are a lot siliconchip.com.au Atmel’s AVR, from JED in Australia Toyota’s sensible solution for speedo calibration It has been a while coming but like all good things, it was worth the wait. Since my letter in the February 2007 issue on the major speedo error in my Toyota Yaris, Toyota has recently fitted it with a new instrument panel. I recently spent 1.5 hours checking the new speedo at the same location as the original test. Several runs were made on the near perfectly straight 8km section of road. Speeds tested were 60km/h, 80km/h and 100km/h. The test regime was to drive for about one kilometre at the steady indicated speed on the speedo, before taking a photograph of the GPS, for each speed range tested. The reason for this was to allow the GPS to stabilise for an accurate reading. The odometer was also checked over a 10km distance, as measured by the GPS. The results were as follows: (1) 60km/h indicated; GPS reading 57.4km/h (2) 80km/h indicated; GPS reading 76.7km/h (3) 100km/h indicated; GPS reading 97.0km/h (4) Odo 10km indicated; GPS reading 9.91km This test revealed a fixed error margin of indicated speed versus actual road speed, over all speed ranges tested. The average speed difference was slightly less than 3km/h. It would appear that the replacement instrument panel has had a total redesign, which possibly incormore expensive to produce and more demanding of the Earths’ resources than the humble incandescent. But this is not to say that the time of the incandescent has not come. Indeed it has, years ago. I used my first Light Emitting Diode back in 1970. It was a tiny red spot of light, good only for indicating at that time but operated “on the smell of an oily rag” compared with other equipment. Forgive me for stating the obvious but LEDs have come a long way since then. siliconchip.com.au JED has designed a range of single board computers and modules as a way of using the AVR without SMT board design porates intelligent microprocessor handling of sensor inputs relative to displayed speed, over the tested speed range. The original instrument panel had a fixed error percentage over its tested speed range, meaning the faster the vehicle speed, the worse the error between actual road speed and indicated speed. Both instrument panels were tested for odometer accuracy and found to be within 1% difference between indicated and the GPS over a 10km distance. The results of this test have proven that the new instrument panel has far greater accuracy than the original. The small fixed speed reading difference between indicated and actual speeds is very acceptable and should take into account any small mechanical or tyre variations over the service life of the vehicle, and still be compliant with the relevant Australian Design Rules. Jack Chomley, North Rockhampton, Qld. Comment: what a great result. This proves that car manufacturers can produce a speedo which is reasonably accurate while still allowing for mechanical and tyre variations. I can’t claim to have any direct experience of the high-power LEDs but they must be on the threshold of replacing domestic lighting by now? True, they are currently much more expensive than incandescents or CFLs but that would partly be offset by their durability. My current 100W reflector lamps are now over $4 a pop (pun intended), which happens fairly regularly). Mass production on the scale required to replace our current lighting must surely bring the price of 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 This board uses the AVR570 module and adds 20 An./Dig. inputs, 12 FET outputs, 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 October 2007  5 JOIN THE TECHNOLOGY AGE NOW with PICAXE Developed as a teaching tool, the PICAXE is a low-cost “brain” for almost any project Easy to use and understand, professionals & hobbyists can be productive within minutes. Free software development system and low-cost in-circuit programming. Variety of hardware, project boards and kits to suit your application. Digital, analog, RS232, 1-Wire™, SPI and I2C. PC connectivity. Applications include: Datalogging Robotics Measurement & instruments Motor & lighting control Farming & agriculture Internet server Wireless links Colour sensing Fun games Distributed in Australia by Microzed Computers Pty Limited Phone 1300 735 420 Fax 1300 735 421 www.microzed.com.au 6  Silicon Chip Mailbag: continued Aeolian radio and the Orchestrelle Company I work in the piano industry and know the Aeolian name very well. They also made pipe organs and they owned the name “Pianola” which like “Rollerblades”, “Thermos”, and “Esky” (possibly today also “iPod”) became a household name. I was wondering whether the name quoted under the radio picture on page 95 of the August issue is correctly spelled. Orchestrelle was the name associated with pianos and music sales as far as I can tell. Would you like to check this? Similarly, Beale in Sydney made radios and pianos. The piano serial number reference book I use shows Orchestrelle LEDs down considerably. I would like to see some comparisons between incandescent, CFLs and LEDs, both in terms of end user cost, depletion of earth resources and disposal problems. Brian Critchley, Elanora Heights, NSW. Comment: we have no doubt that LEDs will eventually replace many incandescent lamps used in domestic lighting, as they already have in cars. Adaptive Turbo Timer may be unnecessary In your August 2007 article, it states, “If your car has been running, it is vital to allow the engine to idle for a few minutes before switching off”. This statement would have been correct in the 1970s. In the early 1980s, automotive turbochargers were fitted with water jackets around the rear bearing of the turbocharger. This is often referred to as water cooling which is not a good name for it, as it gives the impression that the “water cooling” keeps the turbocharger cool while the engine is running. This is not the case. The oil keeps the bearings and shaft lubricated and cool while the engine is running. The turbine shaft temperature is around 200°C while running. as a UK company along with Weber which was also associated with Aeolian. There used to be an Orchestrelle music retailer in Melbourne, as there was Palings and Nicholsons in Sydney. Many of these shops sold radios, records and musical instruments. Some older readers may remember Melbourne stores Suttons, WH Glen, Carnegies, Christies and Maples. It is possible that some of these music instrument retailers could have sold radios too. Paul Smith, Albert Park, Vic. Comment: we referred this question to the HRSA and they have informed us that the company name was Orchestrelle. In the very early days (pre water cooling), the engines were idled so the engine oil could take away the heat of the turbine wheel. If you turned the engine off after hard work, the temperature of the shaft would be so high that the oil would burn and leave a layer of carbon on the bearings and the bearing housing. If you repeatedly shut the engine down while hot, the bearing area would coke up with burnt oil. In the 1970s, Buick fitted turbochargers to their motor vehicles. They had over 50% turbocharger failure rate in the warranty period, so a solution was needed. Water-cooling was the answer and it reduced the failures to fewer than 2%. The water-cooling does its work after you turn the engine off. As the heat from the turbine wheel and turbine housing soaks into the bearing area, the water is heated and starts to rise. This pulls cooler water from lower in the cooling system. The process is called “thermo siphoning”. Over about a 20-minute period, the cooling system turns over and keeps the shaft and bearing temperatures to less then 200°C. After this, the temperature drops away. The only time it is recommended to idle a turbocharged engine is where siliconchip.com.au Speedo calibrations & ADR specification I agree with your editorial comment in the August issue (page 5) that “it may be time for the ADR speedo regulations to be updated”. It might seem odd for an electronics magazine to be discovering solutions to problems in the automobile industry but often people working in any industry stand too close to the trees to see the forest and solutions to problems are discovered by people in other industries. I think your seemingly casual comment is an example of this phenomenon and that your analysis leading to the comment is much more significant and important than you realise yourselves. Only a few years ago, I would have agreed with the comments by Warwick Woods and Max Williams in the Mailbag pages of the September issue. However, a phenomenon that was little more than a curiosity then has become a problem now because of the more or less random coincidence of several otherwise unrelated changes. Firstly, the police are enforcing speed limits more diligently and more precisely. In the olden days, it was more or less common knowledge that the police set their equipment to allow a relatively large margin. While they did that, it was relatively unimportant that our speedos were poorly calibrated. Secondly, speed cameras have be- you have been working the engine very hard and have to stop the car quickly (eg, flat tyre on the highway while towing a heavy load). In a case like this, it is recommended that you idle the engine so you do not shock the cooling system. If you are towing on the highway and come to a town, you can turn the engine off without idling, as you would have slowed down at the city limits. The oil used is very important for turbocharger life. You want an oil that is designed for the high temperatures around the rear bearing. The best advice is use the best synthetic oils and siliconchip.com.au come commonplace. Thirdly, many of us use our cruise control to help us to keep within speed limits even though the cruise control in most vehicles wasn’t and isn’t designed to do that. Max Williams might be interested to note that Mercedes offers at least three levels of “cleverish” cruise control: the C-series has “SPEEDTRONIC” which has some speedlimiting functions; the E-series can be fitted with “DISTRONIC” which can maintain a safe distance behind a vehicle in front; and the S-series can be fitted with “DISTRONICPLUS” which can do the tricks demonstrated on the SBS TV program “Top Gear”. Fourthly, in modern vehicles, most clever functions are implemented electronically and the costs that concern Warwick Woods are mostly artefacts of what the lawyers and accountants think the market will pay. While only one manufacturer offers accurate calibration, they can and will charge a premium but once it becomes commonplace, it will also become affordable. Max Williams asks us to respect the work of the people who prepared the current ADR regulations. I agree that we should do that. We should also ask them to keep doing good work and to prepare new regulations that recognise the changes since the old ones were prepared. Keith Anderson, Kingston, Tas. forget the timers, as they do nothing on a water-cooled turbocharger that the water-cooling already does. Ray Hall, Ray Hall Turbocharging, Cairns, Qld. Comment: the quote “If your car has been running, it is vital to allow the engine to idle for a few minutes before switching off” is a misquote from the article in the August issue. The actual statement made was “If your car’s turbocharger has just been running, it is vital to allow the engine to idle for a few minutes before switching off”. Consequently, the Adaptive Turbo We’re told we make the best speakers in the world… Now you can too “The best speakers I have ever heard” DVD Now “The best bass in the world” Rolling Stone Magazine “We have yet to hear another system that sounds as good” Best Buys Home Theatre Seven models from $769pr www.vaf.com.au FreeCall 1800 818 882 vaf<at>vaf.com.au October 2007  7 Mailbag: continued GPS-disciplined oscillator stability The idea that phase-locking an oven-controlled crystal oscillator (OXCO) to the 10kHz output of a Jupiter GPS timing receiver is a useful thing to do is an illusion (as referred to on page 98, SILICON CHIP, August 2007). The 10kHz output is phase-modulated (more of a jerk than smooth modulation) every second to keep it in sync with the next PPS output pulse. This behaviour is welldocumented in the data sheet if it is read carefully. Between phase jerks the stability of the 10kHz output is no better than that of the receiver’s crystal oscillator. The short-term stability of this 10kHz output is no better than that of the PPS output. The same time loop bandwidth is required when locking to the 10kHz or PPS outputs, to achieve equivalent performance. The fact that a number of people have made the same mistake in believing the 10kHz output has high short term stability doesn’t change the conclusions. Measuring the short-term stabil- Timer does just what is required and that is to keep the engine running when necessary, straight after turbo boost usage. This provides the best form of turbo cooling because when the engine is running the turbo is cooled by the oil pumped through the bearing and a separate water-cooling system (if fitted). Alternatively, without the Adaptive Turbo Timer, if the engine is switched off when the turbo bearings are very hot, the water and oil cooling are also effectively stopped. Whether to run the engine after turbo use should be decided according to the car manufacturer’s recommendations. Suspect sensor design in tank level meter It’s good to see some more articles that promote environmental change, namely the Tank Water Level Indicator 8  Silicon Chip ity of any such GPS-disciplined standard is relatively simple as their short-term stability is so bad. All you need is a low-noise stable OCXO like an FTS1200 (or selected HP/ Agilent 10811 or similar) to measure the instability for measuring times from 1-100 seconds (1000 seconds or more with a good FTS1200 (or a good 10811) and a high resolution counter. If you want to measure the Allan variance, then the type of counter used is important. A resolution of 1 part in 110 is fairly easy to achieve. With a more elaborate set-up, a resolution of 114/averaging time can be achieved, however OCXOs locked to the 10kHz output of a Jupiter GPS receiver are so unstable such high-resolution techniques are not necessary. The SILICON CHIP GPS reference will have an even worse instability for such averaging times so that this should be relatively easy to measure. Even an HP5370A/B can achieve a resolution of around 2E-11/averaging time. Bruce Griffiths, Hamilton, NZ. in the July 2007 issue of SILICON CHIP. I have no qualms about the design in general; it is a novel way to achieve the task. The thing I was puzzled with was the use of the 555 to drive the “critical” LED. This could have been done more simply with a 2N7000 FET and as such, the zero gate current would not light the last red LED and all would be happy! However since the 555 has been installed, wouldn’t it have been a wise move to make the 555 an astable and actually flash the critical LED? However, I do have a problem with the water level sensor. The method using the resistance of the water is fine except for the use of the enamel wire. Now I don’t know what it would be like at these low voltage levels but enamel wire used in electric motors, alternators, transformers, inductors, etc, definitely doesn’t like the presence of moisture. I would imagine that the enamel insulation on the wires inside the pipe would only last a few months and then the calibration would go up the spout! The only suggestion that I have here is that the holes in the pipe where the wires slip through be sealed with silicone or equivalent suitable sealer (difficult task to get perfect). The bottom of the pipe should then be sealed with the manufacturer’s blocking plug and the pipe then submerged in the tank to test for leaks. This will be difficult because the pipe will now want to float! However, if this is achievable, the pipe can then be filled with say castor or olive oil, something not harmful to humans. The top would need to be covered to prevent water washing the oil over and insects making a mess. The oil level in the pipe would need to be just a little higher than the water level as oil is lighter than water. Alternatively, the pipe could be filled with epoxy or a safe grease once the circuitry was thoroughly tested. I’m not sure what expanding foam is like either although it is messy to work with. Any of these filler ideas requires the pipe to be leak-proof before filling. Terry Thrum, Para Hills West, SA. Comment: it is true that the insulation on enamelled copper wire can fail prematurely where moisture and high voltage are involved. However, in this case, the applied voltage is extremely low, less than a millivolt. Light pollution still a major problem from unshaded fittings I do hope that the 7-inch spherical outside lights that John Denham has his CFLs in (Mailbag, SILICON CHIP, July 2007) are not of the type commonly referred to as “light bombs” by the astronomical fraternity. This type of totally unshaded light fitting allows at least half of the light to shine, uselessly up into the night sky. Not only is this a waste of energy, it also contributes to the artificial night-time sky glow which diminishes an otherwise glorious view of a starry night sky. Please properly shade all outdoor lighting. The stars are for everyone. Kenneth Cooke, Strathfield, NSW. siliconchip.com.au SILICON CHIP Order Form/Tax Invoice Silicon Chip Publications Pty Ltd ABN 49 003 205 490 www.siliconchip.com.au PRICE GUIDE: SUBSCRIPTIONS YOUR DETAILS (Note: all subscription prices include P&P). (Aust. prices include GST) Your Name________________________________________________________ (PLEASE PRINT) Organisation (if applicable)___________________________________________ Please state month to start. Australia: 1 yr ...................... $A89.50 1 yr + binder ....................... $A105 NZ (air): 1 yr ....................... $A96 Overseas (air): 1 yr ............. $A135 2 yrs ...................... $A172 2 yrs + 2 binders .... $A203 2 yrs ...................... $A190 2 yrs ...................... $A260 Address__________________________________________________________ PRICE GUIDE: OTHER PRODUCTS __________­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­___________________­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­____________________________________ Postcode_____________ Daytime Phone No. ( )_____________________ Email address (if applicable) ___________________________________________ Method of Payment: (all prices include GST on Aust. orders) *SILICON CHIP BACK ISSUES in stock: 10% discount for 10 or more issues or photocopies. Australia: $A9.50 ea (including p&p). Overseas: $A13 each (including p&p by air). *ELECTRONICS AUSTRALIA: project photocopies. Australia: $A9.50 each (including p&p). Overseas: $A13 each (including p&p by air). *BINDERS: BUY 5 or more and get them postage free. (Available in Aust. only): $A13.95 each plus $7 p&p per order. o Cheque/Money Order o Visa Card o Master Card Card No. *ELECTRONICS PROJECTS FOR CARS, VOL.2: Aust. $A14.95; Overseas $A18.00. (Prices include p&p & GST where applicable). Card expiry date: Signature_____________________________ *PERFORMANCE ELECTRONICS FOR CARS: Aust. $A22.50; Overseas $A26.00. (Prices include p&p & GST where applicable). SUBSCRIBERS QUALIFY FOR 10% DISCOUNT ON ALL SILICON CHIP PRODUCTS* * except subscriptions/renewals Qty Item Price Item Description IPTION? R C S B U FREE S gilent a l WANT A a i c spe See the page 71 n o r e off Subscribe to SILICON CHIP on-line at: www.siliconchip.com.au Both printed and on-line versions available Total TO PLACE YOUR ORDER siliconchip.com.au P&P if extra Total Price BUY MOR 10 OR ISSU E BACK ES A 1 0 & G ET DISC % OUN T $A Phone (02) 9939 3295 9am-5pm Mon-Fri Please have your credit card details ready OR Fax this form to (02) 9939 2648 with your credit card details 24 hours 7 days a week OR Mail this form, with your cheque/money order, to: Silicon Chip Publications Pty Ltd, PO Box 139, Collaroy, NSW, October 2007  9 Australia 2097 10/07 DVD Players By MAURO GRASSI Just How Good Are They For HiFi Audio? CD players are now relatively expensive so are there any compromises in using a cheap DVD player instead? We collected a bunch of players and put them through their paces to find out. T HE CLASS-A STEREO Amplifier described in the May to September 2007 issues is an ultra-low distortion amplifier suitable for demanding applications. At $599.00, it’s not cheap to build but that’s a price many people are prepared to pay to achieve excellent performance. 10  Silicon Chip By contrast, the prices of DVD players (most capable of playing almost any format you can think of) have dropped dramatically. As a result, you may be tempted to use such a player to listen to your CD collection through the Class-A amplifier, particularly if your CD player is old or “on the fritz”. Part of the problem is that dedicated CD players are no longer cheap to buy. Nor are they as readily available as they once were. To buy one, you now have to go to a hifi shop and the prices generally start around $400.00. So how well do cheap DVD players perform as far as sound quality is siliconchip.com.au Equipment Power Supply Supply Type Type Signal Level SNR (10Hz to 22kHz) SNR (10Hz to >500kHz) THD+N (10Hz to 22kHz) Toshiba XM5302B PC CD-ROM Drive External Switchmode CD 1.079V -118dB -104dB .03% Sony CDP-XE300 CD Player Internal Linear CD 2.083V -97dB -75dB .003% Tevion TEV1020 DVD Player Internal Switchmode DVD 1.911V -116dB -105dB .05% Magnavox MDVD50 DVD Player With Tingle Terminator Internal Switchmode DVD 2.018V -115dB -95dB .006% Panasonic DMR-ES10 DVD Recorder Internal Switchmode DVD 2.185V -117dB -94dB .004% Audio World AW8032 DVD Player Internal Switchmode DVD 1.728V -111dB -93dB .006% Toshiba Satellite A30 Notebook DVD Drive (Via Headphone Jack) External Switchmode DVD 0.539V -75dB -55dB 0.3% Table 1: typical audio characteristics of a range of equipment, as measured by our Audio Precision test set. All the players are double insulated, differing only in the type of power supply (switchmode or linear). Players with THD+N of .05% or higher can be expected to sound mediocre. concerned? Can cheap DVD players be used in place of much more expensive, better quality CD and DVD players? Is there a difference between CD and DVD players in terms of audio performance, even for the better quality units? We decided to find out. Audio Precision gear To obtain an idea of the audio quality of a range of equipment, we used our Audio Precision Test Set to test a selection of players owned by various staff members of SILICON CHIP. The players tested included DVD players, CD players and CD ROM drives (including one in a notebook). The results are summarised in Table 1. All players were checked using the 1kHz 0dB sinewave track from the Technics SH-CD001 CD test disc. In each case, we measured THD+N (total harmonic distortion) and SNR (signalto-noise) ratio. In summary, Table 1 shows: (1) the type of power supply used and whether it is inside or outside the case; (2) the RMS signal output voltage; (3) the SNR with and without audio band filtering; and (4) the distortion with audio band filtering (which is substantially better than the distortion measured without audio band filtering, especially for the switchmode equipment). Note that although the cheap DVD players like the Tevion TEV1020 had quite good SNR figures, they exhibited siliconchip.com.au Fig.1: block diagram of the Zoran Vaddis chip, version 888. It is a single chip solution for DVD players and DV recorders. The device includes the motor drivers, an RF amplifier and a processor, as well as various digital interfaces for external memory and external memory cards. In addition, there are input ports for video and audio, and output ports for 5.1-channel surround sound and video. There are also optional connections to hard drives (for DVR applications) and USB ports. Finally, there is a display driver, button decoding and remote control inputs. Chips of this series are found in many different DVD players. relatively high distortion and audible hum. The midrange DVD players like the Magnavox MDVD50 and the Audio World AW-8032 both had better distortion figures. The more expensive DVD players like the Panasonic DMR-ES10 (a DVD recorder) also performed well, with good distortion and SNRs. Note that all these DVD players are double-insulated with switchmode supplies and for reasons to be explained shortly, produce audible hum when connected to any earthed stereo amplifier. By “earthed” we mean an amplifier with a 3-core power flex and 3-pin plug. On the other hand, the older Sony CDP-XE300, a CD player rather than a October 2007  11 This inside view of the Tevion TEV1020 DVD player shows just how few parts there are. The switchmode power supply PC board is to the left of the disk tray with the arrow indicating the high-frequency transformer. DVD player, uses a linear power supply. It produced no audible hum and its distortion figure was a very respectable .003%, the lowest in the group. But its SNR figure appears to be poor at only -75dB when measured with wide bandwidth (ie, >500kHz) and quite good at -97dB when measured with a 22kHz bandwidth (ie, restricting the noise bandwidth to the audible spectrum). This deserves some explanation. Most CD players produce significant noise above the audible spectrum and this is usually filtered out during measurement to produce the manufacturer’s Equipment Case Potential Relative To Earth Tevion TEV1020 DVD Player 81.5V AC Magnavox MDVD50 DVD Player 115.8V AC Panasonic DMR-ES10 RVD Recorder 111.4V AC Audio World AW-8032 DVD Player 117.3V AC Table 2: these are the case potentials we measured for a range of doubleinsulated switchmode equipment. While the voltages are perfectly safe in normal operation, they can give you an electric shock. 12  Silicon Chip typical specification of -96dB or better. The out-of-band noise (ie, supersonic noise) is mainly due to the switching artefacts of the CD player’s DAC (digital to analog converter). These switching artefacts will depend on the oversampling frequency used by the DAC. For example, players that use 2-times oversampling will have their main switching artefacts bunched at 88.2kHz and at the harmonics of that frequency. The Sony CDP-XE300 appears to have a 1-bit DAC and therefore its main switching artefacts appear at around 1.1MHz. Considering that its wideband noise was only -75dB with respect to 2V, the equivalent noise signal at 1.1MHz is around 300 microvolts (300mV) or so. In other words, it is quite a significant RF noise signal to be injecting into the audio input of any audio amplifier. We will have more to say about this aspect, later in this article. Still on the Sony CDP-XE300, it is about 10 years old and a look at its internals revealed it uses 4558 op amps in the output stages. Incidentally, these same op amps are also found in the cheap Tevion TEV1020 DVD player, although they are surfacemount types. As an aside, where a CD player or DVD player is fitted with standard op amps, it may be possible to gain an improvement in performance by retrofitting one of the latest high-performance op amps such as have been featured in recent SILICON CHIP designs; eg, the National Semiconductor LM4562 or the Burr-Brown OPA2134. The Toshiba CD-ROM drive and the Notebook CD-ROM drive both had mediocre performance. However, the latter’s output was measured via the headphone jack, which might explain its distortion and SNR figures. DVD player problems DVD players present two problems as far as their audio performance is concerned. The first is that they always deliver a video output signal, even when playing CDs. This can introduce high-frequency noise into the audio signal and although this may not be audible, it can degrade the signal-tonoise ratio. A more serious problem is the audible hum injected when a DVD player with a switchmode power supply is connected to an earthed amplifier. These days many, if not all, CD players also have switchmode supplies and so they have the same problem. siliconchip.com.au The Sony CDP-XE300 CD Player has a linear power supply with a conventional mains transformer (arrowed). Fig.2: the yellow traces in these scope shots show the voltage across an earthed 100W resistor connected to the case of the Magnavox MDVD50 DVD player. The lefthand window shows the measurement when the Magnavox is floating and the installed “Tingle Terminator” is disabled, while the righthand window shows what happens when the “Tingle Terminator” is connected. The vertical scale is 20mV in both cases. To understand the problem, we need to refer back to our article on the “Tingle Terminator” described in the July 2006 issue. This provided a simple solution for preventing the mild electric shocks that one can receive when using modern double-insulated equipment with switchmode supplies. Because double-insulated equipment is not earthed, the equipment’s case can be at a large potential relative siliconchip.com.au to earth. While this is perfectly safe, it can give you a mild electric shock if you touch it. In practice, the case can sit anywhere between 80V and 120V – see Table 2. By contrast, compare the values in Table 2 with a measured case potential of just 22V for the Sony CDP-XE300, a double-insulated CD player with a linear supply. The “Tingle Terminator” was a workaround to the shock problem. It used a 22nF capacitor to couple the case to earth, effectively removing the shocks. In fact, with the capacitor in place, the case voltage drops dramatically to anything between 2V and 5V. The “Tingle Terminator” was design­ ed as an add-on to existing equipment, whose installation did not require opening the case or modifying the October 2007  13 Fig.3: the yellow trace of this scope shot shows the output from the Tevion TEV1020 DVD player for what should ideally be a clean 1kHz sinewave but which instead has superimposed noise. The red trace is the Fourier transform and this shows that higher frequencies are being superimposed on the output by the switchmode power supply. Notice the large spike at around 146kHz. Each division represents 25kHz. Fig.4: the yellow trace shows the noise output of the Tevion TEV1020 DVD player when it is paused. The red trace is the Fourier transform and this indicates that a range of high frequencies are present in the signal, beginning with the first peak at 27MHz (the crystal frequency of the main IC). High signal amplitudes at higher frequencies are also present right through the FM band and beyond. Each division represents 100MHz. 2-pin mains plug. This was done to 134mA is flowing. The large highcircumvent possible issues with void- frequency spikes have disappeared ing the warranty. and the current flowing to earth has Fig.2 shows the “Tingle Termina- dropped by 17%, yet the 50Hz mains tor” at work. The yellow trace shows fundamental is still visible. This is the voltage across an earthed 100W what produces the hum in the audio 1% resistor connected to the case of signal, even with the “Tingle Terminathe Magnavox MDVD50 DVD player. tor” installed. This signal is essentially the 50Hz Therefore, although the “Tingle Terfundamental from the mains supply. minator” may be effective at removing Large spikes and high-frequency noise the risk of shocks, it is not useful for from the digital circuits inside are also removing the audible hum. present. Compare the top window, taken Switchmode power supplies when the “Tingle Terminator” was The power requirements of a typical disabled, to the bottom window, when DVD player are +3.3V and/or +5V for it is enabled. In the top window, the the digital system and ±12V for the op RMS voltage is 16.1mV, meaning that amps on the analog side. around 161mA is flowing to earth. By For example, the Tevion TEV1020 contrast, in the bottom window, the DVD player supply RF_SiliconChip_60x181mm.qxd 30/3/07 2:12 PM has Pagea switchmode 1 RMS voltage is 13.4mV and around that produces ±12V for three 4558 op amps plus a +5V rail for the digital circuitry. This circuitry is based on a single Zoran Vaddis-series chip (see Fig.1), which is a common single-chip solution for DVD players. In older, conventional power suppl­ ies (also known as “linear” supplies), a transformer completely isolates and “steps down” the 50Hz 240VAC mains. By contrast, the output side of a switchmode supply is isolated via a high-frequency switching transformer. While the primary side of a linear supply is quite simple, a switchmode power supply has quite a few components on the primary side of the high-frequency transformer. These typically include a dedicated switchmode controller IC, a switching device and various passive compo- ELECTRO CHEMICALS Chemical Technology 14  Silicon Chip • Dust Off • Freezing Spray • Electronic Cleaning Solvent No. 1 • Electronic Circuit Board Cleaner • Electrical Contact Cleaner Lubricant • Video Head Cleaner • Ultrasonic Bath Cleaner • Isopropyl Alcohol • Protek • Contact Treatment Grease • Contact Treatment Oil • Solvent Diluted Oil • Contact Cleaning Strip • Circuit Board Lacquer • Q43 – Silicon Grease Compound • Heat Sink Compound Contact us to find your nearest distributor: sales<at>rfoot.com.au Tel: 02 9979 8311 Fax: 02 9979 8098 Richard Foot Pty Ltd, 14/2 Apollo Street,Warriewood NSW 2102 siliconchip.com.au Fig.5: the top left and top right windows show the noise output from the Class-A Amplifier at 20W into an 8W load, at a vertical scale of 100mV and 20mV respectively. No discernible hum is present – the waveform is simply random noise. At bottom left is the noise output of the Magnavox MDVD50 DVD player connected to the Class-A Amplifier (100mV vertical scale). In this case, a 50Hz fundamental is present and can be heard as hum. Compare this with the bottom right window, which shows the noise output of the Sony CDP-XE300 CD player in the same conditions. No audible hum is present. nents, including capacitors connected to ground. As the switching element is either at saturation or off, the efficiency is quite high. Switchmode advantages Switchmode supplies have several advantages over linear types. They can easily step up or invert voltages, they are more efficient and they require a much smaller transformer since they switch at a much higher frequency than 50Hz. Their high efficiency in turn equates to low heat and the smaller transformer makes them cheaper and lighter than conventional supplies. Most cheap DVD players are extremely light for this reason. Noise is the problem Although switchmode supplies are siliconchip.com.au efficient, they produce noise in at least three ways. First, there is ripple at the switching frequency (typically in the kHz range) in the regulated output and ripple injected into the unregulated input supply. Second, there is also radiated noise at the switching frequency and its harmonics. This noise emanates from the inductors and the high-frequency transformer. Thirdly, as already described, the switchmode supply configuration introduces earth loops which in turn causes hum problems. What happens is that the capacitors on the primary side of the switchmode supply couple the mains input through to the signal ground, which connects to the case. As a result, when the signal outputs are connected to an earthed amplifier, current flows to the amplifier’s earth, since the case of the double-insulated equipment is at a high potential. This earth current degrades the SNR and causes audible hum in the amplifier’s outputs. Note, however, that this is only a problem if the amplifier is earthed and the switchmode equipment is double-insulated (ie, not earthed). By the way, if you have this problem, don’t even think of disconnecting the amplifier’s mains earth to cure the problem. That would only serve to create a potentially fatal situation in the event of a fault in the amplifier. Unfortunately, the noise problem doesn’t end there. Since a DVD player also produces a video output signal, the noise component of its audio signal is potentially of a much wider bandwidth than for a dedicated CD player. To see how bad it can be, we measOctober 2007  15 Fig.6: the yellow and pink traces are the left and right channels respectively of the Class-A Amplifier. The cyan trace is the distortion signal produced when the Magnavox MDVD50 DVD player, connected through the Class-A Amplifier, is paused. In the lefthand window, the Magnavox is powered by its internal switchmode supply. By contrast, in the righthand window, the Magnavox is powered by an external linear supply. Notice that the 50Hz hum present in the lefthand trace has disappeared in the righthand trace. ured the Tevion, the worst in our group of DVD players. First, we measured the radiated noise from its switchmode power supply, as shown in Fig.3. As shown, the yellow trace is the audio output from the right channel of the Tevion TEV1020 DVD player. It should be a clean 1kHz sinewave but it has a lot of superimposed noise. The resulting measured distortion figure is high at .05%, as indicated in Table 1. Using a pick-up loop placed near the switchmode supply of the player, we measured the induced current produced by the electromagnetic field of the high-frequency transformer. The resulting noise waveform had a frequency around 130kHz, which we assumed is the switching frequency for this model. The red trace in Fig.3 is the Fourier transform of the 1kHz audio output and it shows a large peak at 146kHz, again close to the suspected switching frequency, confirming that there is noise being injected from the power supply into the audio output. It gets worse It gets worse, however, when we look at the higher frequency noise – see Fig.4. The yellow trace is the noise output from the right channel of the Tevion DVD player when it is paused, while the red trace is the rectangular Fourier transform. The latter has its first large peak at 27MHz, which is the fundamental crystal frequency of the main IC. Large peaks follow all through the FM band, with smaller peaks then following as the frequency increases right up as far as 675MHz – that’s right Equipment Power Supply Switchmode Signal Level SNR (10Hz THD+N (10Hz to 22kHz) to 22kHz) Sony CDP-XE300 CD Player Internal No 12.65V -77dBr .003% Magnavox MDVD50 DVD Player Internal Yes 11.28V -82dBr .009% Magnavox MDVD50 DVD Player External No 11.28V -94dBr .012% Tevion TEV1020 DVD Player Internal Yes 12.65V -75dBr .051% Tevion TEV1020 DVD Player External No 12.65V -100dBr .052% Table 3: the audio performance of various players connected through the 20W Class-A Stereo Amplifier. All are normally switchmode powered except the Sony CD player. The table also shows the difference to the SNR when an external linear supply is substituted for an internal switchmode supply in the two DVD players. The signal level of 12.65V represents 20W into 8W load. 16  Silicon Chip up in the UHF TV bands! As a result, when connected to an FM/AM stereo receiver in order to play a CD, not only can it blot out all AM radio reception from that receiver, but it can blot FM radio reception as well. In addition, the same DVD player can produce audible high-frequency noise through the speakers of the amplifier it is connected to. We don’t know whether other cheap DVD players have the same problem but given that they probably use the same Zoran LSI chip, many equally cheap DVD players could easily be just as bad or even worse. The hum problem Let’s now go back to the main issue, which is audible hum. Of all the players tested, only the Sony CDP-XE300 CD player (ie, the player with the linear power supply) exhibited a quiet output signal when it was paused while connected to the Class-A Stereo Amplifier. The other players, especially the cheap DVD players like the Magnavox MDVD50 and the Tevion TEV1020, all exhibited audible mains hum under the same circumstances. Take a look now at Fig.5. The two top windows show the noise output of the Class-A Amplifier when the inputs are shorted with a 1kW resistor. Two different vertical scales are shown: 100mV/ div for the left window and 20mV/div for the right window. No hum can be seen in the signal nor can any hum be heard through headphones. siliconchip.com.au In the bottom left window, the cyan trace shows the noise output of the Magnavox MDVD50 DVD player when it is paused while connected to the Class-A Amplifier. Hum is now clearly visible in the form of a 50Hz fundamental sinewave and this comes from the mains. The vertical scale is set at 100mV. Now compare this with the noise output of the Sony CDP-XE300 CD player, shown bottom right at the same vertical scale. No discernible hum is present, nor can any be heard. To verify this, we connected one headphone channel directly across the amplifier’s speaker terminals, using the circuit shown in Fig.8. This further confirmed that the switchmode DVD players produced hum while the linear supply CD player did not. Not satisfied with this, we performed yet another test – see Fig.6. The yellow and pink traces are the left and right channels respectively of the Class-A amplifier. The cyan trace is the distortion signal produced when the Magnavox MDVD50 DVD player is connected to the Class-A Amplifier and paused. There’s an interesting twist here though. In the top window, the Magnavox was powered by its internal switchmode supply. However, in the bottom window, the switchmode supply was disabled and the Magnavox was instead powered by an external linear supply that we patched in. Notice that the 50Hz hum that’s present in the top trace has disappeared in the bottom trace! Audio performance Finally, we measured the audio performance of the Magnavox MDVD50 DVD player, the Tevion TEV1020 DVD player and the Sony CDP-XE300 CD player when connected to the ClassA Stereo Amplifier. Their SNR and THD+N measurements are shown in Table 3. We measured the SNR of the Class-A Amplifier at 20W into 8W to be -107dB with 1kW shorting jacks. Table 3 shows that changing the switchmode supply to a linear one improved the audio performance of the two DVD players. For example, the Tevion TEV1020 DVD player had a SNR of -74dB when connected through the Class-A Amplifier (at 20W into 8W) when using its internal switchmode supply. However, this improved by some 25dB to -99dB siliconchip.com.au Fig.7: this diagram shows the linear power supply we developed to replace the switchmode supply in the Tevion & Magnavox DVD players. earthed audio amplifier. Even so, a cheap DVD player may be an attractive proposition for playing audio CDs in non-critical situations. This particularly applies if your listening position Fig.8: this circuit can be used to protect is far enough away from stereo headphones that are connected the speakers to render the directly to the outputs of a stereo amplifier. The 10W resistors limit the current, while hum inaudible. the four diodes limit the maximum voltage Substituting an exacross each earpiece to about ±0.6V. ternal linear supply for the internal switchmode supply certainly gets rid when it was powered by an external of the hum. In fact, we went so far linear supply! as to design a suitable linear supply that could be retrofitted to cheap DVD Conclusion players. These tests lead us to just one conIn the end, however, we scrapped clusion. If you want the very best audio the idea – the audible hum problem performance from your hifi system, was not sufficiently bad to warrant the then a dedicated CD player with a lin- extra cost of the linear supply. It also ear supply is the only way to go. DVD does nothing to improve a mediocre players may cost a lot less but their THD+N performance. switchmode power supplies introduce If you want the very best, buy a good SC audible hum when connected to an CD player. October 2007  17 Agilent’s new 5000 series digital scopes have a simple control layout that belies their very high performance. It is the closest thing we have seen to an intuitive scope, providing a wide range of performance features such as waveform measurements, maths functions, deep memory, high resolution display and triggering on all video waveforms including HDTV. Agilent DSO5054A 4GS/s 500MHz 4-channel digital scope Review by Mauro Grassi T here are so many different digital scopes on the market that many prospective buyers probably think they are all much the same. Nothing could be further from the truth! Each manufacturer has a different philosophy in producing a mix of performance and ease of use, control presentation and a host of operating features. Few digital scopes are truly intuitive 18  Silicon Chip to use, even to people who are very familiar with these instruments. Some have deep multi-level menus and all will have common features, which are sometimes easy to access while others can be quite difficult. Having said that, the digital scope scene does not appear to have changed very much over the last few years, as the principal players have been slow to bring out new models. Well, that has just changed with the release of the 5000-series digital scopes from Agilent Technologies (previously Hewlett-Packard). We had a chance to use the top-ofthe-range 4-channel Agilent DSO5054A for a few days and we came away very impressed. For a start, it has a very simple control layout. Each vertical input channel has its own sensitivity and vertical shift controls and the knobs are colour coded to match the traces siliconchip.com.au Fig 1: the green trace in the top window shows a digital pulse train. The bottom window is the result of zooming in on the un-shaded area in the top display. The top line displays the vertical scales of the four channels, showing that only channel 2 is being used, and the timebase of 200ms/ div is displayed. The top line also says that the un-shaded area in the top window, being expanded below, is 5ms/div, giving a magnification factor of x40. Fig 2: the green trace is a sine wave at around 84Hz. The purple trace is a square wave at around 1.2kHz. The frequency measurements of the waves can be seen midright, while the FFT of the square wave is shown in grey in the bottom part of the display, showing peaks at the odd harmonics. Rectangular mode is selected and the vertical scale (in dB) and the offset in dBV can be selected. The FFT sampling rate stands at 50kS/s. on the screen. This means that you do selectable AC or DC coupling, shown Displaying a signal is easy, as one of not go through the annoying charade of by dedicated LEDs when enabled on the nicer features of this scope is the changing the sensitivity control only to each channel. “Auto-Scale” feature. This is found in find that you have changed and shifted most modern scopes, yet this scope is The Cooks tour the wrong trace! That can be extremely exceptional in this regard. annoying when you have three or more Let’s take a tour of some of the feaSimply connect the probe to your traces on the screen. tures of this scope. The first thing to signal source and press the “AutoThe display looks very bright and notice is the integrat ed help provided Scale” button. Both the triggering sharp. It has 256 intensity levels conby this scope. Pressing and holding mode and the vertical and horizontal trolled by a knob and a high resolution down any button brings up a detailed scales are quickly changed to accomXGA (1024x768 pixels) colour display on-screen message to explain its funcmodate the active waveforms on the that allows fine details to be seen. The tion. That applies to any of the soft screen in an optimal viewing configuintensity of the grid can also be indebuttons as well. ration. Waveforms that are not present pendently controlled. So there is no need to operate “blind” are automatically disabled from being Timebase controls are immediately with this machine. It will tell you what displayed. to the top right of the screen and there to do (well, you do need some clues By the way, Auto-Scale works on all is a button to select main and delayed about operating scopes!) in any of 11 active channels and it neatly separates time-bases. languages. When a knob is turned to the traces on the screen. Any signal Below those are two buttons for its limit, an on-screen bubble pops up with a peak-to-peak amplitude of at measurement: Cursors and “Quick saying so. When a button or knob has least 10mV and a frequency above 50Hz Meas” and below those again a pair of no current function and it is pressed, is automatically displayed. buttons for Save/Recall and printing the scope again tells you. Auto-scale can also be undone at (or dumping to USB the touch of a button flash drive) screen to return to the previgrabs. ous setup! Moreover, Each BNC input the scope does a good Input channels: .................4 has auto-sensing job of selecting auAnalog Bandwidth: ............DC to 500MHz for probes and can tomatic settings and Sampling Rate: ..................4GS/s half channel or 2GS/s for each channel also provide power waveforms can be Memory Depth: .................1Mpts half channel or 500kpts for each channel for active probes. grounded or centred. Vertical Sensitivity: ............2mV/div Individual chanThe former disVertical Resolution: ...........8bits and up to 12bits in high resolution mode nels have selectable plays the waveform LCD display: ......................6.3inch colour TFT XGA, 1024x768 pixels, input impedances with its lowest point 256 levels of intensity control of 50W and 1MW, corresponding to the bandwidth limitbottom edge of the Weight: .............................4.1kg ing to 25MHz and screen, while the cen- Specs at a glance siliconchip.com.au October 2007  19 Fig 3: the green trace shows an AM signal, with a 20MHz carrier frequency. The amplitude and frequency of the signal are shown on the bottom of the display, showing an amplitude of 670mV and a frequency close to the carrier frequency. The carrier frequency was generated by a crystal oscillator on an especially-made board used for demonstrating the scope’s features. tred mode adjusts the waveform to have its middle point in the centre of the screen. The vertical sensitivity can be adjusted in either mode and while the trace is easier to find in the centred mode, this scope allows the vertical scale to be adjusted in the grounded mode and the display is regularly scaled to fit the trace in the best viewing position. This is a very nice feature not readily found in other scopes, where changing the vertical scale often means shifting the trace off the screen! After displaying a trace on the screen, you will probably want to do measurements. So just press the “Quick-Meas” button. You will get a display of the four most recently selected measurements or if none have been selected, you get the signal frequency (provided you have at least one full signal cycle displayed) and the peak-peak voltage for channel 1. Pressing one of the soft buttons (socalled “soft” because they can have many functions) brings up a choice of 23 measurements (duty cycle, rise time, fall time, RMS, standard deviation, max, min etc). You can select the measurement by multiple pressing of the same button or scrolling down through them using the illuminated knob. If that is not sufficient, you can also use cursors to measure points on the waveform. Two cursors on both 20  Silicon Chip Fig 4: the green and purple traces are sine waves, which are out of phase by 180°. The unshaded area in the top window is expanded in more detail in the bottom window. The traces are labeled by user-selectable strings. The bottom line shows the frequency of the green trace and its RMS voltage of 2.201V, its positive duty close to the expected 50% and the phase difference with the purple trace of –177°. vertical and horizontal scales can be selected, shown as dashed orange lines. The cursors can also operate in binary or hexadecimal modes. For example, when sampling a digital signal in binary mode, the cursor can let you know whether the signal is high or low at any point of the waveform. This is displayed as a 4-bit binary string, having one bit for each of the four channels. This can tell you, say, that the waveform is high at 60ns from the trigger point. Running through some of the specs, the DSO5054A has a fast sampling rate up to 4GS/s and has a deep memory of up to 1Mpts (depending on the number of channels in use). This means you can view and store waveforms at high sampling rates for longer. It also means you can zoom in on waveforms and see finer details that you might otherwise miss. This is important for any demanding debugging application. Coupled with its fast refresh rate of 100kHz, the result is a very powerful scope. While other scopes have deep memory modes that can be enabled when needed, this scope has deep memory that is always on, the socalled Mega-Zoom feature. While most scopes will sample at their highest rate at the fastest timebase setting, the sampling rate will drop as the timebase is stretched, simply because the onboard memory is limited. Having a deep memory is therefore essential to sustain high sampling rates for longer periods, allowing more of the waveform to be seen at any one time. The DS5000 series scopes have useful maths functions, including FFT (fast Fourier transform) for spectrum analysis, differentiating and integrating functions, as well as arithmetic operations. This is the first digital scope we have seen with integration and differentiation. Integration is useful if you would like to measure the energy consumption of a circuit, for example. Channels 1 and 2 can be added, multiplied and subtracted and the result displayed as another trace. This can be useful in many situations, not only to compare two waveforms. If you want to know more about a waveform’s frequency components, you can use the FFT function. The FFT can take its input from any of the four channels and even from the result of adding, subtracting and multiplying two of the channels! It can operate in three modes: Rectangular, Hanning and Flat-top. Each is suited to different applications. The Hanning mode has high frequency accuracy and can be used to compare the frequency of two waveforms. The trade-off is less amplitude accuracy. Flat-top mode is useful for high amplitude accuracy of frequency peaks, while Rectangular mode is a good all round mode with good amplitude siliconchip.com.au Fig 5: the yellow trace is mains interference at 50Hz, with an RMS voltage around 400mV and peak-to-peak voltage around 2.2V. The blue background trace is a previously stored version of the same signal but with averaging applied. Stored waveforms can be recalled onto the screen and superimposed on real time signals. and frequency resolution. The FFT is indeed fast and this was the continuing impression we had of this scope. It is truly fast. Pressing the ‘Preset’ button in the FFT menu will cause the settings to change to allow the whole spectrum to be displayed on the screen. This can be considered a kind of “Auto-Scale” feature for the FFT! Standard Connections The DSO5054A has a variety of interfaces. There is the usual GPIB port, an Ethernet port, a USB device port and two USB host ports. The latter are useful for connecting a printer (allowing direct printing of the screen on compatible HP printers) and dumping screen grabs of waveforms onto a USB flash drive. Waveforms can be labeled with an alphanumeric string. There is even a predefined library of labels with common strings like ALE (address latch enable), CLOCK, etc. If you want a larger display, there is an XGA video output port. When connected to a large LCD monitor, the result is a good-looking display that is bright and easy to read. Remote control of the scope is possible through Agilent’s software suite, allowing waveforms to be uploaded to a computer for further analysis. Screen grabs can be saved directly as bit maps, PNG graphics files, or exported in CSV (comma separated siliconchip.com.au Fig 6: the voltage waveform (in purple) across a small motor as it is switched on. Superimposed on this is its FFT (Fourier transform) showing large peaks at some low frequency harmonics, degenerating into more unordered peaks as the frequency increases. The FFT is operating in Rectangular mode and the sampling rate is 50MS/s. values) format for use in a spreadsheet. For more advanced applications, you can program the scope using Agilent’s IO Library suite. Acquisition & triggering Four acquisition modes are available: normal, averaging (up to 65536 sweeps!), peak detect and high resolution. Peak detect mode is useful for debugging applications, where fast glitches cannot be missed. In this mode, the waveform is sampled at the highest rate and maximum and minimum points are stored in memory. This is useful for seeing narrow glitches in the waveform that can easily be missed within a relatively low frequency signal, which most scopes will sample at the less than the maximum sampling rate. This scope has advanced TV triggering modes, from the usual PAL and NTSC, to HDTV1080i/50 and generic modes for composite video signals. As such, it will be appreciated by technicians working with the latest video formats. The Pattern Triggering mode allows each channel to trigger on a low, high or “don’t care” level, or on edge transitions. Each channel can be defined to trigger on any of these. Pulse width triggering allows triggering on a high or low pulse of selectable width. The hold-off period for triggering can be adjusted and this controls the amount of time that the triggering circuit is delayed before it is re-armed. This allows a more stable display of complex waveforms. We should clarify the specifications for this scope. The maximum sampling rate is 4GS/s in half channel mode. This means that only one of channels 1 and 2 can be used and one of channels 3 and 4 can be used. When all channels are used, ie in full channel mode, the maximum sampling rate drops to 2GS/s. A similar caveat applies to the memory depth. What’s the damage? The recommended retail price of the DSO5054A is $14,231 (according to the Agilent website), which is very competitive for an oscilloscope of such specifications. It is supplied with four Agilent 10073C passive probes with automatically detected 10:1 attenuation rated at 400V peak-to-peak CAT II, a carry case and manuals. Agilent’s software suite, including programming libraries and DLLs can be downloaded from the Agilent website. For further information on the Agilent 5000 series scopes, have a look at the Australian Agilent website at www.home.agilent.com/agilent/ product.jspx?cc=AU&lc=eng&ckey= 875171&nid=-35642.0.00&id=875171 or contact the Australian distributors SC Trio Smartcal. October 2007  21 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 It’s the modern-day equivalent of one of the world’s first “computer games” OSCAR: 2007 STYLE B y B R I A N H E A LY Noughts and crosses may rate quite poorly amongst young gamers of today but in the late 1960s, a machine, more often called an electronic brain than a computer, playing noughts and crosses against a human opponent, was quite a sensation. T HE FIRST COMPUTERS WERE built during World War II to attempt to decode German coded signals. From this early work sprung “EDSAC” (for Electronic Delay Storage Automatic Calculator), the first truly programmable computer. It was built at Cambridge University (UK) in 1949. This computer, shown in the background above, was used by mathematicians for research and learning. It 26  Silicon Chip contained 3000 valves and consumed some 12kW of power! History was made in 1952 by A.S. Douglas, a young PhD student, when he used it for another purpose: he programmed it to play noughts and crosses. The computer used a cathode ray tube to display its output, which means this was the very first video game in the world. In the mid-1960s, both Sydney and Melbourne technical museums at- tracted large crowds with a “computer’ which played noughts and crosses against a human opponent. In 1968, when the author was aged 24, he and a friend built a machine using 70-odd telephone relays and a uniselector to play the game. A uniselector, by the way, is a rotary, solenoid driven, 50-position switch. They were commonly used in automatic telephone exchanges at the time and were even found in some siliconchip.com.au This is a Uniselector, a 50-way solenoid-driven switch. Every automatic telephone exchange used these in their thousands – now they are virtually a museum piece. The Uniselector was used as the basis for the original “Oscar” built by the author back in the 1960s. older exchanges until quite recently, before first solid-state devices and then microcontrollers took over. In a busy telephone exchange, the noise of the uniselectors switching back and forth following the numbers dialled on a phone perhaps 10 kilometres or more away was quite deafening! Our machine was as large as a refrigerator and about twice as heavy! We called him “OSCAR” and he worked very well. When you pressed a button for your turn, the machine started whirring loudly (the sound coming from the uniselector), a row of lights flashed, relays clicked in and out and finally it all stopped as it brought up its reply. It was very impressive. We hired it out to retailer David Jones and a new shopping centre called “Westfield” in Wollongong (a large city south of Sydney) where it attracted large crowds. It must be very difficult for people who did not come through that era to understand such a reaction, so I will try to explain. It was akin to the crowds who gathered on footpaths outside electrical retailers a decade or so earlier to watch that new-fangled invention, television, playing in the windows. In 1968, very few people had ever seen a computer “in the flesh”. They may have seen one in a film where typically it would be in an almost sacred situation, a series of large metal cabinets, some with large tape spools rotating and all attended by well groomed, bespectacled technicians, wearing white lab coats, hovering over it like nurses over a new-born baby. What the computer actually did was a complete mystery and there was no way you were ever going to be able to get close enough to touch one. So, if suddenly you were now able to have contact with a computer, to challenge it at a game that you unD1 1N4004 K 4.7k 4.7k 14 Vdd 16 1 RA2 RA1 18 A1 OSC1 100pF A1 MCLR IC1 PIC16F84A RESET S1 K RB5 11 RB4 10 RB3 9 A1 LED1  3 OSCAR'S FIRST TURN S2 S3 Vss RA3 A1 A2 A1 A2     S5 K LED7 S7 S6  K  S4 A2 LED8   S8 S9 K S10 S11 2 5 2007 A1 A2 A2 LED4  K K K 8 RB2 RB1 7 6 RB0 RA4 A1 LED5   A2 LED9   K A2 LED2  A1 A2 LED6   K 17 RA0 RB7 13 RB6 12 4 A1 A2 LED3  SC 'OSCAR'  +6V 10 F 100nF 4.7k 10k A – 2007 version (RED) A1 K A2 (GRN) 0V LEDS1–9 1N4004 A K Fig.1: not a Uniselector in sight (or even hidden!). The PIC chip does all the work of the mechanical monster of 40+ years ago – and this OSCAR is much easier to build. siliconchip.com.au October 2007  27 new game and the red button is to allow OSCAR to have the first move in the game. It is polite and fair to give OSCAR the first turn at least sometimes. OSCAR is very clever here, as the square he chooses for his first move is truly random. Generating truly random numbers is difficult for a PC and very difficult for a PIC but OSCAR employs a trick here. At the end of a game, following a reset, OSCAR is not just sitting there doing nothing – not at all. He is repeatedly counting rapidly from one through to nine at high speed, until you press a key to start the game, at which time he stops counting. The number that he stops on will be the square he chooses if you give him first turn. How it works This clipping, believed to be from the “Wollongong Mercury” around 1968, shows the original fridge-sized OSCAR noughts and crosses machine. No, those aren’t LEDs in the display – they weren’t even a glint in a mad scientist’s eye back then . . . derstood well, this was very exciting. Lots of my older friends still remind me about OSCAR. We initially did not know even how to start to build such a machine. We eventually worked out that the machine had to go through a logical series of steps, in sequence. We never called it a program but of course, it was a program. I have never forgotten the sequence, so now that PICs have become available, I set out to put the exact same program from the 1968 OSCAR into a 2007 PIC16F84A. The new OSCAR The new OSCAR is a tiny fraction of the size of the original. And instead of requiring a lot of power to operate, it will run for months on a couple of batteries. It has nine green buttons in a 3 x 3 array and nine bicolour LEDs, also in a 3 x 3 array. 28  Silicon Chip When you press a button, to take your first turn, the corresponding LED illuminates green. OSCAR now “thinks” for a second or two and then has his move, illuminating his position red. It is then your chance to have your second move – and I think you know the rest. If OSCAR wins, which is pretty common, the winning row of three red LEDs flashes, calling attention to the player’s demise(!) and the game is halted. You cannot continue when you have been defeated. The first version of the software was wriiten so that OSCAR never lost a game. However, that quickly becomes boring and so the software was later reworked to give its opponent a chance to win approximately one in 10 games. If you do win, your three green LEDs will flash to indicate success. There are two more buttons. The white button is to reset OSCAR for a If you glance at the circuit you will see that it is quite simple and does not use any active components apart from the PIC. The circuit is powered from four AA batteries that sit in a plastic battery box available from Jaycar. The maximum voltage for the PIC is 6V, so don’t be tempted to install a 9V battery. This PIC can have various oscillators but in this case, we are using a resistor/capacitor circuit on pin 16 of the chip. With the values chosen, the circuit oscillates at around 700kHz. The RC oscillator is a little cheaper and somewhat slower than a crystal, making delay loops easier. You can see the 700kHz triangular waveform on pin 16 with a ’scope and high impedance probe. The PIC divides this by four to become the system clock and you can see the resulting 180kHz square-wave on pin 15. Because we are connecting so many devices to the PIC, we need to do some multiplexing. The PIC has only 13 input/output connections available, but we have nine position buttons, nine red LEDs, nine green LEDs and a couple more buttons. If you have a look at the circuit you will see that for each of the nine locations, the common cathode of the green/red LED and one side of the pushbutton are all connected together. So we have a common connection for the button, red LED and green LED, and of course there are nine separate common points. The PIC holds these lines high at 5V and then, one at a time, drops the line siliconchip.com.au + 4.7k OSCAR'S FIRST TURN RESET 10k 10 F 1 IC1 PIC16F84A S2 4.7k 4.7k 100nF 0V 100pF D1 +6V S1 17001180 LED7 LED4 LED1 LED8 LED5 LED2 LED9 LED6 LED3 1CIP RACSO S9 S6 S3 S10 S7 S4 S11 S8 S5 Fig.2: follow this parts layout diagram and the accompanying photo to assemble the unit. In the prototype, ordinary copper wire was used for the links but we suggest tinned copper wire to prevent oxidation. to 0V for around one millisecond, then puts it back up to 5V and drops the next one to zero for one millisecond and so on. So the PIC is scanning from one to nine, relentlessly, regardless of the state of the game. Let’s now look at pins 1 and 18 of the PIC. These pins are configured as outputs and are normally held low by the PIC. Pin 1 connects to all the green LED anodes and pin 18 connects to all the red LED anodes. If, during the scanning, the PIC needs to illuminate, let’s say, green LED number six, it waits until the scanning reaches position number six and then, just for one millisecond, while the cathode is held low, it raises the anode via pin 1 of the PIC to 5V. Only that LED will light because it is siliconchip.com.au the only one with power on one end and 0V on the other end. In this way, the PIC lights the LEDs one at a time at high speed, so you are unaware that they are actually flashing rapidly. It will never light both green and red for the one location, as that situation never occurs. The common sides of the pushbuttons are all connected to pin 2 of the PIC. This pin is configured as an input and is normally held high by a 4.7kW resistor. However, if you press a button, this pin will be pulled low when the scanning reaches that position. During an actual game, as the PIC is scanning each position, then for the one millisecond when the common point is pulled low, pin 1 will be switched high if the LED should be green. Similarly, if the LED should be red, pin 18 will be switched high. If the position is not occupied (no red, no green), then (and only then) the PIC looks at pin 2 to see if a button has been pressed. This means that if the player presses the button for a position already occupied, it is ignored. Software Let’s ignore the housekeeping software and just look at the game logic itself. When you press a button, the green LED is illuminated immediately, and then there is a deliberate delay of 1-2 seconds so that OSCAR appears to be “thinking”. Then the PIC very rapidly goes through four separate procedures, looking for a response. As October 2007  29 These two shots give a good idea of how OSCAR fits together. The PC board screws to the box lid via standoffs with the switches and LEDs poking through, while the battery is fixed to the bottom of the box. soon as a response is indicated, the PIC executes it and quits any further procedures until the next move. The first procedure, called “Win for Sure” is to test every position to see if in any row of three LEDs, there are two red LEDs lit and the third position blank. If it finds one, it of course puts a red LED there, stops the game, declares a win, etc. The second procedure is called “Prevent Win” and is similar to the first. Its job is to test every row to see if there are two green LEDs in a row and a third position blank. If it finds one it puts a red LED there to prevent defeat. The third procedure is the most difficult. It is called “Tactics”. It goes through quite a few algorithms and tries to do something intelligent. The fourth procedure, if the first three produce nothing, is simple: just find an empty position and go there. There is more software for responding when the player lets OSCAR have first turn and also to highlight the winning row of three red LEDs by making them flash. Assembly The whole circuit is built on one PC board which mounts inside the lid of a jiffy box. The most difficult part of the construction process is the precise drilling of the lid. Photocopy or cut out the front panel art and use it as a template. Tape it to the jiffy box lid and drill a small pilot hole for each marked spot. That done, increase the size of the drill, being careful to keep the drill perpendicular to the lid at all times. Check that the LEDs will fit into the holes easily and that the buttons have about 1mm clearance all around. If the switches get caught on the hole edges and jam on, the project won’t work! Assemble all the components onto the board except the LEDs. This is important – leave the LEDs until later. It’s best to use a socket for the PIC in case you need to remove it. The end of Parts List – OSCAR Noughts & Crosses Game 1 1 1 4 9 1 1 1 4 8 OSCAR PIC1 PC board, code 08110071, 145 x 86mm 158 x 95 x 53 mm (UB1) jiffy box (Jaycar HB6011) 4 x AA battery holder with switch (Jaycar PH-9282 AA batteries green PC-mount pushbuttons (Jaycar SP- 0724) red PC-mount pushbutton (Jaycar SP- 0720) white PC-mount pushbutton (Jaycar SP- 0723) 18-pin IC socket M3 x 10mm tapped metal stand-offs (Jaycar HP-0900) M3 x 6mm screws Semiconductors 1 PIC16F84A preprogrammed with OSCARv2.hex (IC1) 9 red/green 3-terminal LEDs (WES Components LED5GRY) 1 1N4004 silicon diode (D1) Capacitors 1 10mF 16V electrolytic capacitor. 1 100nF miniature polyester capacitor (code 104, 0.1 or 100n) 1 100pF ceramic capacitor (code 101 or 100p) Resistors (0.25W, 5%) 1 10kW (code: brown black orange gold) 3 4.7kW (code: yellow purple red gold) 30  Silicon Chip siliconchip.com.au 0v OSCAR’S FIRST TURN +6v R A C O OSCAR PIC1 S 5677s +6v RESET Figs.3 & 4: full-size artwork for the front panel (which can also be used as a drilling template) and the PC board, viewed from the copper side. Note the four cutouts required in the corners of the PC board so it can clear the pillars in the box. the socket with the notch in it is near the edge of the board. Leave the PIC itself out for the moment. Fit all 18 wire links on the PC board (we suggest using resistor and capacitor lead cut-offs as these are invariably tinned copper wire) and the four resistors. The small electrolytic capacitor is polarised. Install the four 10mm metal standoffs to the PC board. Test fit the board to see how well you have drilled the holes for the buttons; file or ream the holes a little if necessary. When you are happy with the fit of the buttons in the holes, fit all nine LEDs into the holes in the board, taking great with the polarity (flat side is on the anode 1 [red] leg) but don’t solder them just yet. Now mount the board on the lid using the standoffs and fit the screws siliconchip.com.au to both ends, so that the board is in its correct position. That done, push the LEDs one at a time hard into their corresponding holes in the lid. Make sure each LED is fully pressed into its hole, then solder its leads. Repeat until all the LEDs have been soldered in. If you have done this well, all the LEDs will be protruding through the lid by the same amount (around 3mm). The battery box can be attached to the bottom of the jiffy box with double sided tape. Finally, fit the PIC into its socket, install the batteries, switch on and give it a go. Faultfinding If you have any trouble with any of the functions you can check out the board as follows. First power off and remove the PIC, then make a short jumper out of a single strand of telephone wire. Put one end in pin 14 of the socket and the other end in pin 18. Put one end of a 220W resistor in pin 5 and the other into pin 6. The first LED should light red. Swap the resistor end from pin 6 to pin 7 and the second LED should light red. Keep going into pins 8, 9, 10, 11, 12, 13 & 17 and each LED should light red in turn. To check the green LEDs, change the jumper linking pins 14 & 8 to pins 14 & 1. Repeat as above with the 220W resistor and again, each LED should light green in turn. If you have a LED in backwards it will light green when it should have lit red and vice versa. If these checks are OK, then it is highly likely that you have a faulty PIC or a PIC that has not been programmed SC or is programmed incorrectly. October 2007  31 Try your hand at a surface-mount-device project... PICPROBE A versatile PIC-based logic probe that fits inside a Biro case! T HIS PROJECT CAME ABOUT through the recent trend in electronics towards lower operating voltages. If you look around at the latest chips being offered from semiconductor manufacturers you will see that most are designed to operate on 3.3V or lower. Having done a few recent designs with 3.3V circuits, I discovered that my old favourite test tool, the Logic Probe, wouldn’t operate below 5V. I looked around my usual electronic suppliers but couldn’t find anything that would work on anything less than 5V. So I thought I’d build design and one. The first requirement I had was to make it work over as wide an operating voltage as I could so that it could be used on the old legacy 5V systems and down to some of the latest processors at 2.8V. The second requirement was low cost. I took a look inside the existing probes I had, only to discover them to be full of analog components, some of which were now obsolete. 32  Silicon Chip The quickest and easiest approach seemed to be to build something out of a small microcontroller, so I went on the hunt for anything that was small, cheap and worked on a wide supply voltage. Where I ended up was at the Microchip website looking at our old friend, the PIC. One of their latest additions to the ever-expanding family is the 10F20x series which are available in DIP-8, SO-8 or SOT-23-6 packages. The SOT23-6 was my choice as these are tiny and easy to put inside some type of pen as a housing. My next mission was to find a housing for the design. Having built a Logic Pulser from a magazine article many years ago into a white board marker pen, I decided to check out the local stationery shop for ideas. If I could find, from an original by Ross Purdy say, a pen moulded in clear plastic, I wouldn’t need to drill holes to view the LEDs. This would not only make it easier to build but it would look pretty cool as well! I found a 10-pack of ballpoint pens that looked about right and cost only $2.00, making for a very cheap case – including an end cap to protect the pointy bit. The pens were a bit on the small size, allowing for a PC board only about 5mm wide and 100mm long, but it was the height that I was more concerned with. I cut out a dummy piece of circuit board and glued a few bits on and found that the micro and LEDs would fit easily down the barrel of the pen. With the micro and housing sorted out, I next concentrated on the functionality required. First and foremost was a good sharp tip that you can use to probe tiny pitch devices that were/are becoming increasingly common. A sewing needle seemed to fit the bill quite nicely here. siliconchip.com.au This photo shows the first prototype without the extra components added for higher voltage operation or input protection. Don’t forget to keep the pen cap – it can save some nasty stabs! Also note the S1 access hole in the pen body. I also wanted to have a pulse stretching or latching function to view and change very quick pulse transitions so a switch would be required to change modes and clear the pulse latch when required. Modifying the design! You will see from the schematic (Fig.1) that there isn’t much to the design. However, this has some differences to the author’s original circuit and project, with SILICON CHIP making a number of changes. First, SILICON CHIP added provision for a 5V regulator on the PC board, since there would be a lot of hobbyists who might want to use the probe for testing devices with higher voltages. This involved including the pads and tracks for a 5V SMD regulator (78L05, REG1). Due to the miniscule power drawn by the circuit, the regulator should be quite happy working up to its maximum input voltage of 30V. If you only want low-voltage operation, the regulator can be left out and a link added to connect the DC in and DC out pads (where the regulator would be). The regulator input and output filter capacitor can remain – they won’t do any harm and may even do a bit of good in decoupling a supply. We’ve specified 100nF capacitors because we have found these are the easiest to get in SMD and in small quantities. But there would be some benefit if one of the two “downstream” capacitors (ie, between the siliconchip.com.au regulator output and ground) could be larger – in fact, as large as you can get in SMD. The second change was in the input circuitry. The PIC only has six pins, two of which are the power supply. GP3, the probe input, can withstand a maximum of 13.5V. In the vast majority of circumstances this would be more than adequate but once again, we’ve “gilded the lily” somewhat by adding a pair of diodes across the input (one each to the positive supply and ground) along with a series resistor. This protects the input from accidental higher voltages and for the price is a worthwhile addition. This is very handy in case you touch something at a higher potential than the power supply. If you don’t need this protection, the diodes can simply be omitted. The 4.7kW resistor could be retained, or replaced by a wire link if you wish. It won’t matter either way. Circuit details Surface-mount LEDs, so tiny that they are almost impossible to find if you drop them on a carpeted floor REG1* 78L05 OUT +2.8 -5V OR +6 -15V* GND 100nF 100nF IN 180Ω 180Ω 100nF 180Ω A LED1 A LED2 A LED3 λ TS4148* K 5 Vdd D1 4.7k* 10k A 6 PROBE GP2 IC1 PIC10F200 GP3/VPP GP1 K * ONLY REQUIRED FOR HIGHER VOLTAGE OPERATION -- SEE TEXT K K C 4 B E 3 IC1 = PIC10F200 OR PIC10F202 Q1 MMUN2211 1 NOTE: ALL DEVICES IN THIS PROJECT ARE SURFACE-MOUNT Vss D2 TS4148* GP0 λ λ K A 2 S1 0V SC  2007 PICPROBE LEDS (UNDER SIDE) A K 78L05 TS4148 6 IN GND NC A K PIC10F20X OUT GND NC 1 5 MMUN2211 4 C B 2 3 E Fig.1: the circuit can be built in two versions – that shown here, suitable for general purpose work or without REG1, suitable only for low-voltage work. October 2007  33 The SMD LEDs are really bright, especially in normal lighting. This photo clearly shows them glowing even though they have been “swamped” by the very bright photo flash we used for the photo. Parts List – PICPROBE 1 PC board – see text 1 clear plastic ballpoint pen case with top and cap 1 35-40mm long darning needle 1 500mm length thin figure-8 cable, red & black 1 small red alligator clip 1 small black alligator clip 1 ultra-miniature (SMD) momentary action pushbutton switch Semiconductors 1 PIC10F200 or PIC10F202 SMD microcontroller programmed with PicProbe.hex 1 MMUN2211 SMD NPN resistor-equipped transistor (Q1) 1 red SMD LED (LED1) 1 green SMD LED (LED2) 1 orange SMD LED (LED3) 2 TS4148 SMD diodes (D1-D2) 1 5V SMD positive regulator (see text) (REG1) Capacitors 3 100nF SMD Resistors (all 603SMD) 1 10kW 1 4.7kW 3 180W 34  Silicon Chip (trust us!), are directly driven from the PIC’s GP2 (red LED) and GP1 (orange LED) outputs. The green LED is driven by the inverse of GP2, using transistor Q1. Even though Q1 is shown on the circuit as a standard NPN type, it’s a bit more complicated than that. It is actually a “Resistor Equipped Transistor” which has two internal resistors: a series resistor to the base and a pull-down resistor to the emitter. These “RET” devices are great for use as digital inverters. GP0 is normally held high by a 10kW resistor connected to the positive supply. It’s also connected to a pushbutton switch which grounds the input when pressed. Which PIC? The circuit shows a PIC10F200 as the microcontroller but you can also use a PIC10 F202. The program was originally written for the 200, which has 256 bytes of program, 16 bytes of RAM, and one 8-bit timer. Note that neither the PIC10F204 nor PIC10F206 will work in this circuit – you must use the 200 or the 202. Operation The probe has three LEDs and a push button. The Red LED is turned on for a logic 1 at the probe tip while the Green LED turns on for a logic 0. The Orange LED works in one of two modes – pulse stretch or latched. In pulse stretch mode, the orange LED will pulse for 50ms every time there is a change on the probe input. This makes very small pulses at the probe tip viewable. If the orange LED stays on permanently in this mode then the probe tip is changing at a rate greater than 50ms. In latched mode, the orange LED will turn on and stay on with any change on the probe tip. This is handy for detecting very infrequent changes. The latch is cleared and the LED turned off when the button is pressed. The pushbutton has three functions: (1) changing orange LED mode, (2) clearing the latch and (3) enabling a pull-up resistor on the probe tip. To change modes you press and hold the button for two seconds. After two seconds the orange LED with blink to indicate the mode is about to change. When the button is released, the mode is toggled. In latch mode, a single press of the button will immediately reset the latch. If the button is pressed when power is first applied, a pull-up resistor on siliconchip.com.au siliconchip.com.au 0V +V PICPROBE + JAYCAR 100nF JE 100nF TWICE FULL SIZE (FOR CLARITY) REG1 MC785L05 ACTUAL SIZE OF PC BOARD JAYCAR PICPROBE + ALL COMPONENTS ARE SMD AND ON COPPER SIDE OF PC BOARD A 180 K 180 20071129 A S1 10k GND LED3 LED2 JE 20071129 A, B, C AND GND ARE USED FOR IN-CIRCUIT PROGRAMMING D2 KC5457 EC8257 EC8257 SOLDER 4.7k D1 C TS4148 x2 IC1 B A 100nF 180 K LED1 MMUN2211 C K A Q1 B E DARNING NEEDLE (~35-40mm) Fig.2: install the parts on the Jaycar PC board as shown in this twice-size overlay. Note that this assembly differs slightly from the accompanying photo which shows the author’s prototype (ie, no regulator or input protection diodes for working at higher voltages). KC5457 Internally, you don’t get much room to play with in this tiny PIC. Because the device is so small and the task relatively simple, the software was written in PIC assembler using the PIC IDE 7.5 tool kit, which is available free from www.microchip.com. The IDE gives you an editor and assembler and is quite easy to learn. As this micro has no interrupts and very little resources it doesn’t take long to master but as I found out, there are a few traps for young players. The first thing to master is the internal oscillator and its calibration, if required. When the device is manufactured, it has a MOVLW instruction loaded into the last byte of the memory. On power reset, the micro starts at the last address and executes the MOVLW instruction. This loads a calibration value into the “W” register and is factory set. The program counter then rolls around to 0 and starts executing the user’s code. The problem comes when you erase the device and lose the MOVLW instruction. If you want a 4MHz calibrated oscillator you need to read the last byte and write it down then manually put it back in. All this seemed unnecessary for my application as I wanted it to run as fast as possible. As the first instruction I loaded “W” with 0x7E which makes the oscillator run at its fastest speed. The next item to master is the internal timer. This is a bit tricky as the micro has no interrupts to trigger asynchronous events. The timer is freerunning and you can only read the timer register and compare it with a constant. Any write to the timer will clear it and start timing again so you can’t use any read-modify-write instruction. This was a trap I fell into. I have run the timer at 50ms per overflow (counts from 0x3d to 0 in 50ms then is reloaded OUCH! The software with 0x3d). If you check and branch when the timer is zero you can have a routine which is executed at a regular period for timing tasks. The program begins by setting the oscillator configuration, port pin configuration (inputs or outputs), starting the timer, and resetting the LEDs. As the processor has no interrupts the only way to monitor the probe tip is to poll it. This is done in the main loop and the smaller the main loop (or the quicker it executes) the smaller the pulse transition that can be detected. This is one limitation of the design but in practice it doesn’t appear to be a problem. The main loop moves the state of the probe input to the red/green output, checks the status of the mode change flag and looks for the timer to reach zero. Every 50ms, the time function is called. The job of the time function is to check that the button has been held down for two seconds and to update the orange LED in either pulse or latch modes. First we will look at the button down timer. To do this we have a variable called CNT0 which is preloaded with 40. Every time the time function is called we decrement CNT0 if the button is pressed. If it is not pressed, we reset CNT0 back to 40. The only way CNT0 can make it to 0 is if we have 40 consecutive calls to time with the button pressed (40 x .05 = 2 seconds). When CNT0 reaches 0 we set a flag (BDOWN) to signal to the main loop that the mode change function needs executing. The orange LED is handled with different pieces of code depending on the mode set. The flag LATCH determines the mode. Every time the red/green LED changes state we set a flag (CHANGE). This flag is read by the time routine. In pulse-stretch mode, the orange LED is turned on when CHANGE is set and then CHANGE is cleared. If CHANGE is not set, the orange LED is turned off. This means that the minimum time that the orange LED is on will be 50ms which is more than enough for your eye to see. PIC the probe tip is enabled. Normally the pull-up is disabled, which makes the input impedance very high. In this configuration the LEDs will flash randomly until the probe is connected to the target test point. This is very useful for tracking down floating circuits on the target under test. If this is not an issue, then enable the pull-up and the tip will go to a “soft” logic 1. The only way to reset the pullup is to re-power the probe. October 2007  35 Where Do You Get It? PROGRAMMING THE PIC CHIP If you’re not building the PICPROBE from a kit, you must first program the 10F20x micro with the file PicProbe.hex, available from the SILICON CHIP website – www.siliconchip.com.au Since the micro is a surfacemount device, programming it presents added complications. 6 1 It must be done in circuit 2 but before the board is fully 7 3 populated. This section explains 8 how to do this. 4 9 You need both a VPP voltage 5 source of around +13V and a normal +5V supply. If you RS-232 SERIAL have decided to use the 78L05 PORT regulator, you can derive the 5V supply from that. If you have chosen to bypass the regulator, you will need to apply +5V to pin 5 of the micro and 0V to pin 2. The micro must first be soldered in place, making sure that the orientation is correct. If you are using the regulator, solder that in too, then solder both the positive and negative supply leads to the board. Special pads to access pins 1, 3 & 6 of the PIC have been provided on the board specifically for programming. These are labelled, respectively, “A”, “B” and “C” on the component overlay. The pad labelled “GND” can be connected to the external programming circuit shown above. You may solder wires to these pads for the programming phase and later, when the micro has been successfully programmed, remove these wires. Back-up pads for the links required in normal operation have also been provided on the PC board. The type of programmer we recommend is the “COM84” style programmer whose schematic appears above. A computer’s serial port will be required and the software to use is WinPic, available free to download from www.hamradioindia.org/circuits/ winpic.php We used the WinPic version compiled 9th December 2005 but other versions should be similar. After soldering the wires to the A, B and C pads, you should breadboard this circuit. The two BC546 NPN transistors are used to switch on and off the higher programming voltage, which for normal programming 36  Silicon Chip +VPP +5V 2.2k +5V 10k BC546 BC546 2.2k 2.2k 22k 2.2k PIC 10F20x “COM84” COMPATIBLE PROGRAMMER VPP APPROX. +13V 6 (”C”) 3 (”B”) 1 (”A”) 5 PIC 10F20x 2 Both Jaycar Electronics (www. jaycar.com.au) and Altronics (www. altronics.com.au) sell a kit of parts for the PICPROBE. Jaycar’s kit includes a doublesided PC board with plated-through holes and all parts, including a preprogrammed micro but not the pen or the needle. It retails for $14.95 (Cat. KC-5457). The Altronics kit is similar with a preprogrammmed micro and no pen nor needle. It also sells for $14.95 (Cat. K-2587). PIC TO BE PROGRAMMED (ON PICPROBE PC BOARD should be between 12.5V and 13.5V at pin 6. Adjust your input VPP voltage level to within this range. There will be a small voltage drop across the 10kW resistor in series between VPP and the collector of the BC546/pin 6. When the Tx line (pin 3) of the serial port is low, the voltage at pin 6 of the PIC10F20x should be around 0V. When it is high, it should be between 12.5V and 13.5V. The WinPIC software will automatically switch this voltage on or off as required. To access the serial port, we used a serial cable with an IDC 10-pin header attached, as in the photograph below. Once you are satisfied that the circuit is working correctly, you may connect the serial cable to your computer’s COM1 port. Now you should run the WinPic pro­ grammer. You must first select the “COM84” programmer for the serial port in the “Interface” tab. While you are there, check that the interface is working correctly by clicking on the “Initialize!” button. If everything is working OK, you should get the message “Interface tested OK”. If not, double check your wiring. Now go to Device -> Select . . . and select the PIC10F20x as your device. You now should be able to erase, program and read the micro. To load the firmware, go to File -> Load and select the PicProbe. hex file. Then choose Device -> Program to program the micro. If this worked, go to Verify to check that the firmware has been programmed correctly. Latch mode is similar, in that when CHANGE is set the orange LED is turned on but is not cleared until the button is pressed. This is detected using the BPRESS flag. Mode changing uses a separate function labelled “cngmode”. When this function is called it will blink the orange LED using simple delay loops until the button is released. When the button is released, the LATCH flag is inverted and the routine exits back to the main loop. Construction Basically, all the parts are installed on a double-sided PC board – see Fig.2. This board measures just 106 x 5mm and should be a relatively snug fit inside the pen case. Don’t push it all the way in to check, though – you may not be able to get it back out again. Note that the PC board shown in Fig.2 is available only as part of a kit from Jaycar Electronics. Altronics also sell a kit for the PICPROBE, using their own version of the PC board (the assembly instructions are with the kit). Note that because you’ll be building the PICPROBE from a kit, the PIC micro will be supplied ready programmed. You need to decide if you want to use your logic probe for low-voltage work only (as in the original design) or for general purpose, higher voltage work. If it is for low-voltage work only (ie, 5V or less), you can leave out the voltage regulator and place a link between its input and output positions. The first step in the assembly is to carefully solder the SMD devices to the PC board but don’t install the PIC just yet. To install these parts, you will need a soldering iron with a fine pointed tip siliconchip.com.au and a magnifying lamp. A pair of self-closing tweezers can be used to hold each device in position as it is soldered. Once these SMD parts are in, solder on the probe tip, the switch and the external connection wires. As mentioned earlier, the tip is a sewing needle. These are often nickel-plated, which makes soldering a bit difficult. Test it first – if it is difficult (or impossible) to get solder to take, you may need to file off a small section of the nickel plating. The size of the “probe” is up to you – and the type of work you’ll be doing. We’d be Rigol DS5062MA 60MHz Rigol DS5102MA 100MHz inclined to use a small darning 60MHz Bandwidth 100MHz Bandwidth needle, as these tend to have 1GS/s Real Time Sampling 1GS/s Real Time Sampling less of a point (so you won’t 2 Channels 2 Channels get stabbed!) but are still fine Mono LCD Display Mono LCD Display enough for the vast majority 4K Memory Per Channel 4K Memory Per Channel of work. 20 Automatic Measurements 20 Automatic Measurements The needle we used was Advanced Triggering on Edge, Advanced Triggering on Edge, about 35mm long and so far, Video & Pulse Video & Pulse still hasn’t been missed from Built-in FFT Built-in FFT the sewing box (;-). Built-in USB Built-in USB Don’t forget that the power 3 Year Warranty 3 Year Warranty wires (polarised figure-8 cable) need to pass through the pen top cap so it is wise to ONLY $ ONLY $ ex GST ex GST do this now, rather than later. You’ll need to drill a hole in SAVE $300 SAVE $200 the end of the cap to accom* Offer valid until 30th June 2007 or while stocks last. modate the wires. The last component to be fitted should be the PIC chip, Melbourne Brisbane Adelaide Perth Sydney Tel 03 9889 0427 Tel 07 3275 2183 Tel 08 8260 8166 Tel 08 9361 4200 as this allows you to check the Tel 02 9519 3933 Fax 03 9889 0715 Fax 07 3275 2196 Fax 08 8260 8170 Fax 08 9361 4300 Fax 02 9550 1378 LED operation before putting email testinst<at>emona.com.au web www.emona.com.au the PIC chip in. To do this, connect power and in turn short the cathode of each LED to ground (0V). Each should light in turn (you won’t do any harm to Q1 doing this). Next, remove power, wait a few of course equates to a logic high and As you do this, also check that the minutes and then fit the PIC chip to the logic low). colours are correct: red towards the board, taking care with its orientation. Assembly is now complete – all you probe, orange in the middle and green That done, apply power again – the have to do is drill a 2mm hole in the towards the switch. If your LEDs light, LEDs should be flashing in an apparent pen case as shown in the photo to acit’s a pretty good bet that you haven’t random fashion but only one should be cess S1, then slide the completed PC made any mistakes or shorted out any lit when you touch the probe tip to the board into the case until the switch is SC SMD pins. positive supply and then to 0V (which right under the hole. RIGOL SCOPES SALE ... SAVE UP TO $300 1,099 799 EMONA Issues Getting Dog-Eared? Keep your copies safe with these handy binders Available Aust, only. Price: $A13.95 plus $7 p&p per order (includes GST). Just fill in and mail the handy order form in this issue; or fax (02) 9939 2648; or call (02) 9939 3295 and quote your credit card number. siliconchip.com.au REAL VALUE AT $13.95 PLUS P & P October 2007  37 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 Rolling Code Keyless Entry System Versatile IR Unit Also Functions As An Alarm Pt.1: By JOHN CLARKE Ideal for keyless entry for doors in cars, homes & industry, this Keyless Entry System features a rolling code to ensure high security. It also has two door-strike outputs, an alarm system & provision to use up to 16 separate keyfob transmitters with the same receiver. L OTS OF DIFFERENT electronic systems have now been developed for keyless entry. These include systems that require a coded electronic key, such as RF and infrared transmitters, RFIDs (Radio Frequency Identification Devices), keypads and swipe cards. There are also units that do not require a coded electronic key and these include fingerprint, face and iris recognition. Regardless of format, electronic keys 40  Silicon Chip usually comprise a small keyfob-style transmitter and a receiver that goes with the door lock mechanism. The transmitter sends a string of data that is unique to each individual lock and this data must match the data stored in the receiver before the lock will be released. The concept is roughly similar to a standard metal key which has a pattern of peaks and valleys along its length. These peaks and valleys must match the tumblers within the lock in order for the lock to open. With any type of lock, there is always a problem of security. Keys can easily be copied, while many conventional RF and infrared transmitters are far from tamper-proof. One technique is to use a special receiver to intercept and copy the transmitted code. Once copied, the signal can then be re-transmitted to the door lock to gain unauthorised entry. In fact, this technique was commonly used by car thieves in carparks and proved very effective against early electronic locking systems. It could also be used to open automatic garage doors and gain access to buildings. Rolling code security Modern transmitters now circumvent this problem by changing their code each time they send a signal. So if an unauthorised person captures siliconchip.com.au the transmitted code, re-sending this code will not unlock the door. This is because the door lock is now expecting a new code based on an algorithm that both the transmitter and receiver have in common. This code changing technique is commonly called a “rolling code”, although it is sometimes also called “code hopping”. It renders copying useless and thus provides a very high level of security. It is also virtually impossible to send a correct code without having a valid rolling code transmitter. This is because of the huge number of code variations possible. Because of its security advantages, a rolling code transmitter forms the basis of the Rolling Code Keyless Entry System described here. In fact, the odds of picking a correct code at random for our rolling code transmitter are one in 1.4 trillion or one in 1012. If you want to know more about rolling code transmissions, refer to the separate panel elsewhere in this article. Main features Our new Rolling Code Keyless Entry System comprises a small keyfob-style transmitter and a separate receiver. The transmitter is small enough to be attached to a keyring and has two pushbutton switches, each capable of sending a separate code. Each time one of the switches is pressed, a small indicator LED flashes to indicate that the transmitter has sent its code. The larger of the two switches activates the alarm functions of the receiver. It arms the unit so that it will sound an alarm should there be unauthorised access. The alarm functions include an electric door strike control (this allows the door to be opened), two alarm inputs (eg, to monitor doors, windows or other sensors), and an arm/disarm output. The door strike can optionally be set to operate on arming, on disarming or on both. In addition, an alarm output is provided to sound a siren if required. The second, smaller pushbutton switch on the transmitter is independent of the alarm. It can be used to operate a separate door strike or some other device connected to the receiver. Such devices can include a light or a siren that can be used as a panic alarm. This can be optionally set to operate momentarily or can be toggled on and siliconchip.com.au Features & Specifications Transmitter • • • • • • Rolling code infrared transmission Small keyfob style case Dual function buttons Randomisation of code parameters feature Synchronising of parameters feature Up to 16 identifications Receiver • • • • • • • • • • • • • • 12V operation Up to 16 separate transmitters can be synchronised Dual function with an independent output Two alarm inputs with exit and entry delays Two door strike outputs Alarm output Arm/disarm output and LED indicator IR receive acknowledge LED Strike 1 operates on arm, disarm or both Strike 2 operates independently with momentary operation or toggle output Arm output invert option Adjustable door strike, entry/exit delay and alarm periods 200-code look ahead feature Transmitter lockout feature off with each switch pressing. The door strike outputs can be set to operate from between 0-64 seconds, while the inputs can include delayed operation from 0-64 seconds. These delayed inputs allow the alarm to be armed while giving the user enough time to exit the door without setting off the alarm. An identical delay period allows the alarm to be disarmed on entry. During the exit delay period, the ARM indicator LED in the receiver unit flashes on and off at a 1-second rate. At the end of the exit delay, this LED indicates that the unit is armed by flashing briefly once every second. This conserves power and increases its effectiveness when it comes to attracting attention. An Acknowledge/Power LED is also included in the receiver. This normally flashes with a very short duty cycle. However, when the receiver picks up a signal from the transmitter, the Ack/ Power LED flashes at a very high rate. It also shows if the received code is invalid by momentarily blinking off and on. If the code is correct, the receiver responds to the signal. The transmission range is about 4m which should be sufficient for most purposes. Note, however, that it will not work if the IR receiver is in direct sunlight. Setting it up Before using the Infrared Rolling Code Alarm, both the transmitter and the receiver must be set up correctly. First, each transmitter must be given a separate identity ranging from 1-16. This is selected using link options on the transmitter board but note that no two transmitters should be given the same identity. Second, the transmitter must be randomised. This changes the initial rolling code and algorithm parameters to ensure that the transmitter code is going to be unique. The third step involves synchronising the transmitter and receiver. This process involves sending the rolling October 2007  41 Parts List Receiver 1 PC board, code 01510071, 61 x 122mm 1 UB3 plastic utility box, 130 x 68 x 44mm 5 2-way PC-mount screw terminal blocks (5mm or 5.08mm pin spacing) 1 SPST vertical mount micro tactile switch with 0.7mm actuator (S1) 3 3-way pin header terminal strips (2.54mm spacing) 4 2.54mm jumper shunts 3 PC stakes 1 25mm length of 0.8mm tinned copper wire 2 10kW horizontal trimpots (code 103) (VR1,VR2) Semiconductors 1 PIC16F88-I/P microcontroller programmed with irrcroll.hex (IC1) 1 78L05 low-power 5V regulator (REG1) 1 38kHz infrared receiver (IRD1) 2 BD681 Darlington NPN transistors (Q1,Q2) 2 BC337 NPN transistors (Q3,Q4) 1 16V 1W zener diode (ZD1) 4 1N4004 1A diodes (D1-D4) 1 1N5404 3A diode (D5) 2 3mm red LEDs (LED1,LED2) Capacitors 5 100mF 16V PC electrolytic 3 100nF MKT polyester 3 10nF MKT polyester 1 1nF MKT polyester Resistors (0.25W, 1%) 4 10kW 1 220W 2 2.2kW 2 100W 2 1kW 1 10W 2 680W code parameters to the receiver, as described next month. You can synchronise from 1-16 transmitters, provided each has a different identity. Also included is a facility to prevent any or all transmitters from operating the receiver once they have been synchronised. This “lockout” feature can be useful if a transmitter has been lost and you no longer want it to work with your alarm system. 42  Silicon Chip Test Components 4 red LEDs 4 2.2kW 0.25W 1% resistors Transmitter 1 PC board, code 01510072, measuring 30 x 36mm 1 keyfob remote control case (Jaycar HB-5605 or equivalent) 1 12V A23 car alarm battery (9.5 diameter x 27mm) 2 SPST SMD tactile switches 6 x 6 x 3.85mm (S1,S2) 1 TO-3P transistor silicone insulating washer cut to 20 x 24mm 5 PC stakes 1 25mm length of 0.8mm tinned copper wire Semiconductors 1 PIC16F628A-20/SO 18-lead SOIC microcontroller programmed with irxmroll.hex (IC1) 1 MC78M05 DPAK 5V regulator (REG1) 1 MMBT100 SOT-23 SMD NPN transistor (Q1) 1 MMBT200 SOT-23 SMD PNP transistor (Q2) 2 1N4148 diodes (D1,D2) 1 3mm infrared emitting LED (LED1) 1 green gull wing style surface mount LED (2.2 x 2.2mm) (LED2) Capacitors 2 1mF monolithic ceramic 1 100nF monolithic ceramic Resistors (0.25W, 1%) 2 10kW 2 22W 3 1kW A transmitter identity can be locked out individually but if you don’t know the identity of a lost transmitter, all identities can be locked out. The transmitters that are to be used with the receiver are then re-synchronised. Transmitter circuit OK, so much for the background details. Let’s now take a look at how the circuit works, starting with the transmitter – see Fig.1. IC1, a PIC16F628A microcontroller, forms the heart of the transmitter circuit. The circuit might look quite simple but there are a lot of “smarts” hidden inside the PIC micro, including the software necessary to generate the rolling code. Under normal conditions, switches S1 & S2 are open circuit and transistor Q2 is off, so no power is applied. This is done to ensure long battery life. If power were continuously applied, the current drawn from the battery would be around 4mA because of the quiescent current of the 5V regulator. Conversely, pressing either S1 or S2 connects the 12V battery to the input of regulator REG1 via diode D1 or D2. A 22W resistor is included in series between the battery and the switches to limit the initial charging current into the 1mF bypass capacitor at REG1’s input. This minimises wear on the switch contacts. When power is applied to REG1’s input, its output delivers a regulated +5V rail to IC1. As a result, the micro powers up and runs its internal software program. One of the first things the program does is check which switch was pressed (this happens after a short delay to make sure the switch is fully closed). In operation, the program can decide if S1 or S2 is pressed because of the 10kW resistor connected between S2 and the micro’s RA4 input. It works like this. Initially, RA4 is set low by the program. This pin is then made open circuit so that it can be pulled high if switch S2 was closed. However, if S1 was closed instead, the RA4 pin will stay at 0V. By checking the voltage on RA4, the program can thus determine which switch was pressed and initiate the correct function codes for that switch. The 10kW resistor is necessary to limit the current into the internal clamping diodes at RA4 when S2 is closed. In practice, the positive clamp diode will conduct, clamping the RA4 input to 0.6V above the +5V supply. This protects the input from damage. Diodes D1 & D2 protect the regulator from reverse polarity should the battery be inserted the wrong way around. These diodes also isolate the switch outputs from each other, so that the RA4 input will only go high if S2 is pressed. If S1 is pressed, the 12V at REG1’s input reverse biases D2 and so siliconchip.com.au Fig.1: a PIC16F628A microcontroller forms the heart of the transmitter circuit. It contains all the software necessary to generate the rolling code and drives an infrared LED (LED1). is blocked from reaching RA4. Next, the program sets RA2 at pin 1 of the micro high. This output drives the base of NPN transistor Q1 via a 10kW resistor. As a result, Q1 switches on and this in turn switches on transistor Q2. This action latches the supply to regulator REG1, even if switch S1 or S2 is released. This is necessary to allow time for the rolling code calculations to be made and stored without interruption, otherwise the code may become corrupted. It also ensures that the rolling code is transmitted in its entirety. The next stage in the program involves calculating the code and storing the values. This calculation is based on the previously transmitted code and uses an internal algorithm. Once calculated, the new code appears at outputs RB0-RB5 which in turn drive an infrared LED (LED1). The 22W resistor in series with LED1 limits the current to a safe value. In operation, LED1 is driven using 100mA pulses at a rate of 38.46kHz. A high (or a “1”) is transmitted as a 512ms-long burst of 38.46kHz signal, followed by 512ms of no transmission. Conversely, a low (or a “0”) consists siliconchip.com.au of a 512ms period of no transmission followed by a 512ms burst of 38.46kHz signal. LED2 is the Transmit LED and is driven by output RA3 during code transmission. Basically, RA3 goes high each time there is a “1” in the transmitted code, and low each time there is a “0”. As a result, LED2 flashes to mimic the transmission code. Transmitter identity Transmitter identity is selected using the LK1-LK4 link connections to RA1, RA0, RA7 & RA6. As shown, each individual input can be connected to either the +5V supply or the ground supply (0V) but not to both or the supply will be shorted. The number of possible combinations is 16. Each of these inputs is initially tied to +5V on the PC board (via thin PC tracks) and this selection is Identity 1. The other 15 identities are selected by breaking one or more of these connections to the +5V rail and connecting them instead to an adjacent 0V rail. We’ll talk more about this in the construction. In-circuit programming Five-pin header CON1 is provided on the circuit to allow for In-Circuit Serial Programming (ICSP) of IC1 using a PIC programmer. Alternatively, we have developed a surface-mount converter board that will allow IC1 to be programmed directly using a PIC programmer. We’ll publish the details on this next month. The ICSP connections on the transmitter are also used to run the randomisation and synchronisation functions using a bridge between pins 3 & 5 and 3 & 4 respectively. IC1 runs at a nominal 4MHz, as provided by an internal oscillator. This oscillator has a 1% tolerance and its accuracy is sufficient for this application (ie, there’s no need for a crystal oscillator). However, because the oscillator frequency can vary with temperature, we have included a means for the receiver to lock onto the transmitter’s clock rate, so that variations over a long time period do not matter. By the way, the transmitter uses several surface-mount components so that the circuit will fit into a small keyfob case. These surface-mount parts include IC1, REG1, Q1, Q2, LED2, S1 & S2. The remaining parts are standard through-hole component types that are October 2007  43 Standby current: 0mA Total transmit current: rolling code transmission = 35mA for 80ms; synchronise = 35mA for 100ms; randomisation = 10mA. Infrared transmit frequency: 38.46kHz Code transmission rate: 1.024ms Encoding: a high (or a 1 bit) is transmitted as a 512ms burst of 38.46kHz infrared signal followed by 512ms of no transmission. A low (or 0 bit) is transmitted by a 512ms period of no transmission followed by a 512ms burst of 38.46kHz infrared signal. Rolling code: sends four start bits, an 8-bit identifier, the 48-bit code plus four stop bits. The start bits include a 16.4ms gap between the second start bit and the third start bit. Synchronise code: sent as two blocks. Block 1 sends four start bits, the 8-bit identifier, a 32-bit seed code and four stop bits. Block 2 sends four start bits, a 24-bit multiplier, the 8-bit increment and 8-bit scramble values, and four stop bits. The start bits include a 16.4ms gap between the second start bit and the third start bit. Code randomisation: alters the multiplier values, the increment value, the scramble value and the seed code at a 40ms rate. Infrared transmission range: 4m inputs – Input 1 & Input 2 – and these connect to the RB5 and RB6 inputs of IC1 via 2.2kW resistors. Each input is also bypassed using a 100nF capacitor to filter out transients and thus prevent false triggering of the alarm. When these inputs are open, both RB5 and RB6 are held high (ie, at +5V) via internal pull-up resistors. In practice, this means that you can use normally-open (NO) or normallyclosed reed switch and magnet assemblies to trigger the inputs. If you use an NO switch, the input will normally be high and the system will trigger if a switch is closed. Conversely, if an NC switch is used, the input will normally be pulled low but will go high if the switch is opened. Basically, any change in level when a reed switch opens or closes will be detected and sound the alarm at the end of the entry period – provided that the receiver is in its armed state. Note, however, that the alarm will not sound if the receiver is still within its exit delay period. Receiver Door strike outputs Specifications Transmitter Supply Current: 7.6mA typical when armed and with no external devices powered. Strike 1 period: adjustable from 0-64 seconds in 0.25s steps approximately. Strike 2 period: adjustable from 0-64 seconds in 0.25s steps approximately. Input 1 delay: adjustable from 0-64 seconds in 0.25s steps approximately for exit and entry delays. Input 2 delay: adjustable from 0-64 seconds in 0.25s steps approximately for exit and entry delays. Alarm period: adjustable from 0-128 seconds in 0.50s steps approximately small enough to fit onto the PC board. Receiver circuit Refer now to Fig.2 which shows the receiver circuit. It’s built around infrared receiver IRD1 and PIC microcontroller IC1, the latter operating at 4MHz to match the transmitter’s frequency. Once again, much of the complexity is hidden by the software programmed into the microcontroller. IRD1 only has three leads but inside it comprises a complete infrared detector and processor. First, it receives the 38kHz infrared pulse signal from the transmitter and amplifies this to a constant level. This signal is then fed 44  Silicon Chip to a 38kHz bandpass filter to remove any 50Hz or 100Hz mains signal and other noise. It then demodulates the signal to produce a serial data burst at IRD1’s pin 1 output. This serial data signal from IRD1 is fed to the RB4 input of IC1 via a 100W resistor. A 1nF capacitor filters out any transients. IRD1 is powered from the receiver’s +5V supply rail. A 100W resistor and a 100mF capacitor provide supply decoupling and filtering, to prevent the receiver from producing false signals due to power line changes. As well as the IR receiver, there are two other inputs to the PIC microcontroller. These are alarm sensor When an IR signal transmission is received, the output from IRD1 is processed by IC1. This then drives Darlington transistors Q1 & Q2 as appropriate to control the door strike outputs (ie, Strike1 & Strike2). As shown, Q1 & Q2 are driven via 680W resistors from IC1’s RB0 and RA2 outputs respectively. Diodes D1 & D2 clamp the voltage produced by the door strike solenoid to the supply rail when the transistor is switched off. Transistors Q1 & Q2 are both BD681 Darlington types and can be used to drive loads up to 1.5A. A typical electric door strike only draws about 800mA at 12V. The other two outputs are the Alarm & Arm outputs and these are controlled by transistors Q4 & Q3 (both BC337) respectively. Q4 is driven by IC1’s RB1 output via a 220W current limiting resistor. However, the base current is sufficient for the transistor to remain fully saturated for a 200mA load and this is ideal for many piezo sirens. Similarly, transistor Q3 is driven via a 10kW resistor from IC1’s RB2 output. Q3’s collector provides the Arm output and this can be used as a toggle output to set a second alarm system. Typically, you would use a 1kW pull-up resistor between the Arm output and the +12V rail, so that the siliconchip.com.au D1–D4: 1N4004 D5 1N5404 +12V IN INPUT 1 IN K ZD1 16V 1W 0V REG1 78L05 10 K A +5V OUT +11.4V VR1 10k GND 100 F 16V A 100 F 11 RB5 100nF AN1 2.2k 12 RB6 RB2 100nF INPUT 2 RB1 100 RB0 100 F IRD1 IC1 PIC16F8810 I/P RB4 3  1 100 1nF 2 IRD1 +5V LK1 – + LK2 – + LK3 – 3 1 2 AN0 10nF 10nF + 10k 10k 10k 10nF RA2 RA3 4 15 RA7 RB3 RA5 TPG K D4 K D1 K D2 A A A RB7 100 F TP2 ARM 17 ALARM 18 10k* 8 Q3 E B 220 7 STRIKE 1 C B Q4 E 680 6 STRIKE 2 C 1 LEDS C B 680 Q1 C E B Q2 1k 3 1k 2 +5V 9 13 GND IN + – Vss 5 LK4 ARM INVERT A ACK/ POWER A  LED1 K K INFRARED ROLLING CODE RECEIVER Q3, Q4: BC337 E B C K ZD1 A OUT ARM  LED2 S1 A SC K 78L05 D1–D5 2007 A E SYNCHRONISE RA6 +11.4V * REDUCE TO 1k IF ARM OUTPUT USED TO DRIVE A RELAY RA4 16 D3 A TP1 14 Vdd K 100 F 100nF 2.2k VR2 10k Q1, Q2: BD681 B C C K E Fig.2: infrared receiver IRD1 and PIC microcontroller IC1 are the main parts in the receiver. IRD1 picks up and demodulates the infrared transmissions, while IC1 decodes the data and drives the various outputs. level can swing between 0V and 12V. Alternatively, Q3’s collector could be used to drive a relay coil. In this case, the 10kW base resistor will need to be reduced to 1kW so that the transistor can remain in saturation while driving a 285W 12V relay coil. The unit can be optionally configured with Q3 either on or off when armed. This is set using link LK4. When LK4 is in the “+” position, Q3 is on when the unit is armed and off when disarmed. In this case, the RB3 input is held at +5V via an internal pull-up resistor within IC1. Moving LK4 to the “-” position pulls RB3 to ground and changes the sense of the Arm output. In this case, Q3 is off when the unit is armed and on when disarmed. siliconchip.com.au LED 2 indicates the state of the unit. It’s driven from the RA4 output of IC1 via a 1kW resistor and flashes when the unit is armed. There are two different flash styles. During the entry and exit delay periods, the LED flashes with a 50% duty cycle (ie, it is on for half the time and off for half the time). However, at the end of the delay period, it flashes on for only 4% of the duty cycle (ie, each flash is very brief). Other link options Links LK1, LK2 & LK3 are included to provide further options. For example, LK1 can be tied to either the +5V rail or to 0V, or it can be left open. These three options determine how the Strike1 output operates. Basically, Strike1 can be set to operate when the unit is armed, when it is disarmed or on both arming and disarming. In operation, the software programmed into the PIC micro decides where the link is inserted by running a few tests. First, it takes the RA7 output high (5V) and then sets the RA7 pin as an input to read the voltage. If the voltage is now low, then the link must be in the “-” position. However, if the input remains high, then the link is either in the “+” position or is open circuit (it remains high when the link is open because of the charge on the associated 10nF capacitor to ground). To test if the link is in the “+” position or open, the RA7 pin is made an output again and is driven low (to 0V). The RA7 pin is then changed October 2007  45 Note: transistor Q2 mounts under 10kW resistor These two larger-than-life-size photos clearly show how the parts are mounted on the transmitter board. You will need a fine-tipped soldering iron (2mm diameter or less) and a magnifying glass to do the assembly. Fig.3: follow these parts layout diagrams to build the transmitter board. Note that you have to set the transmitter’s identity before installing IC1 (see text) and don’t forget transistor Q2 – it goes under a 10kW resistor, just below S2. to an input and the level checked again. If the voltage is now high, then the link must be in the “+” position. Conversely, if the voltage is low, then the link is open. The 10kW resistor in series with RA7 is there to prevent shorting when this pin is taken high and low with a link in position. LK2 sets Strike2’s operation for either momentary operation or for Capacitor Codes Value mF Code IEC Code EIA Code 100nF 0.1mF 100n 104 10nF .01mF   10n 103 1nF .001mF   1n0 102 toggle operation. This link pulls the RA5 input either to +5V when it is in the “+” position (momentary) or to 0V when it is in the “-” position (toggle). Note that this link cannot be left open because the RA5 pin can only be used as an input. LK3 is used in conjunction with trimpots VR1 and VR2 to set the various time periods. These include the Strike1 and Strike2 momentary on periods, the entry and exit delays for Input1 and Input2, and the alarm period. As shown on Fig.2, trimpots VR1 & VR2 are connected across the 5V supply and their wipers connect to analog inputs AN0 and AN1 respectively. The voltage applied to each analog input is converted to a digital value within Fig.4: this enlarged track section shows the locations of links LK1LK4 on the transmitter board. The transmitter identity is changed by breaking one or more of the thinned link connections to the +5V rail and bridging them (with solder) to the adjacent 0V rail instead. the software and it is these values that determine the timeout periods. Synchronise switch Switch S1 is the Synchronise switch and this connects to the RB7 input. This input is normally held high via an internal pull-up resistor but when S1 is closed, it pulls RB7 to 0V. Basically, S1 is used to synchronise the receiver with the transmitter. It is also used when setting the time periods. In addition, if S1 is closed during power-up, it selects the transmitter identity lockout function. Power supply Power for the circuit is from a 12V supply such as a battery or DC plugpack. Diode D5 provides reverse Resistor Colour Codes (Transmitter) o o o o No.   2   3   2 46  Silicon Chip Value 10kW 1kW 22W 4-Band Code (1%) brown black orange brown brown black red brown red red black brown 5-Band Code (1%) brown black black red brown brown black black brown brown red red black gold brown siliconchip.com.au Table 1: Transmitter Identity Identity LK1 LK2 LK3 LK4 1 2 3 + + + + + + + + - + + + + + + + + - + + + + + + + + - + + + + + + 4 5 6 7 8 9 10 11 12 13 14 15 16 + + - polarity protection and is rated at 3A so that it can handle the currents that may be drawn by an electric door strike and siren. The 10W resistor and zener diode ZD1 provide transient protection, with the zener clamping voltages over 16V. The 10W resistor limits the current through ZD1 to a safe level. Following ZD1, the supply is filtered using a 100mF capacitor and applied to 3-terminal regulator REG1. The resulting regulated +5V rail is then used to power IC1 and the infrared receiver (IRD1). Power on/off indication is provided by LED1 which also acknowledges the infrared signal. Normally, LED1 flashes with a 4% duty cycle about twice per second. However, when an infrared signal is received, it flashes at the infrared reception rate. LED1 also flashes with an even duty cycle for a short time at the end of synchronisation and if the infrared signal is incorrect. Construction The Infrared Keyless Entry Alarm is built on two PC boards: a receiver board coded 01510071 and a transmitter board coded 01510072. We’ll start with the transmitter assembly which is the trickier of the two. In order to fit in the keyfob case, the transmitter board measures just 30 x 36mm and uses lots of surface-mount components. However, these are not too difficult to solder in, provided you have a soldering iron tip that is just siliconchip.com.au The keyfob case is supplied with the key switch covers mounted as shown here. This assembly must be removed. Fig.5: once the switch covers have been removed, the flanges are ground down using 180-grit sandpaper, so that only the tops remain (see text). 2mm in diameter or finer. A magnifying glass (or, preferably, a “maggie lamp”) is also required to check your soldering, while a length of 1.5mm de-soldering braid (solder wick) would also be useful for cleaning up any excess solder that may flow between connections. Fig.3 shows the parts layout on the PC board. The first step is to check the PC board carefully for any breaks in the copper or shorts between tracks. Repair any faults that you do find (rare these days), then check the shape of the board. It should have a curved front edge and a small circular cut out at the other end. In addition, there should be two slots for the battery clips. Next, check that the PC board fits neatly into the base of the keyfob case. If it does not fit, it’s just a matter of filing it neatly along the edges until it does. Setting the identity Before mounting any of the parts, it’s first necessary to set the transmitter’s identity but only if more than one transmitter is to be used. If more than one transmitter is used, then each will require a unique identity. As supplied, the PC board initially Above: the finished transmitter board inside its keyfob-style plastic case. Power comes from a 12V A23 car alarm battery. Note how the keyswitch covers are mounted on the lid, using a 20 x 24mm silicone washer – see text. Right: the two keyswitch covers are attached to the 20x 24mm silicone washer as shown here. Use silicone sealant to “glue” them in place. The keyfob lid can be used as a template to position them correctly. October 2007  47 Fig.6: follow this diagram to mount the parts on the receiver board. Use a socket for the PIC microcontroller and take care to ensure that all polarised parts are correctly orientated. The infrared receiver module (IRD1) can either be mounted on the board (as in the prototype) or connected via shielded cable (see diagram next month). ties links LK1-LK4 to the +5V supply rail. This is Identity1, or ID1. If only one transmitter is to be used, then you don’t have to do a thing – just leave it at the default identity (ID1). If you do wish to change the identity, it’s just a matter of altering one or more of the links as shown in Table 1. You do that by breaking the link’s thinned connection to the +5V track and connecting it to the adjacent 0V track instead via a small solder bridge. Make sure, however, that a link connection is not made to both the +5V and 0V tracks. We have labelled the +5V connection with a plus (+) sign and the 0V connection with a minus (-) sign. It is important to select the identity now because the +5V track section cannot be accessed when IC1 is in place. The +5V connections should only be broken with a sharp craft knife and, once broken, should not be resoldered. That’s because IC1 would no longer sit properly on the board, making it difficult to solder its pins. The selected identity should be marked on the back of the PC board using a marker pen. For example, if the identity is 2, write ID2 on the PC board. This number can also be written on the back of the keyfob transmitter case, in the indentation provided. If you are building the unit from a kit, then IC1 will be supplied preprogrammed. If not, you will have to program the PIC yourself using a suitable programmer. As previously mentioned, we have provided two programming options, the first of which is to use the in-circuit programming connector on the PC board. Alternatively, you can build and use the surface mount adaptor board to be described next month, so that IC1 can be programmed out of circuit. Parts assembly Except for a single wire link, all parts for the transmitter mount on the copper side of the PC board. Don’t install the link yet though – that step comes after you install IC1. To install IC1, position it on the board with its pin 1 at top right – see Fig.3 (pin 1 is indicated by a small adjacent dot in the body of the IC). Carefully adjust it so that its pins line up with the tracks and use a clothes peg (or some other small spring-clamp) to hold it in position. That done, solder a couple of diagonally opposite pins, check that everything is correct, then remove the peg and carefully solder the remaining pins. The main thing to watch out for here is unwanted solder bridges between adjacent tracks. If this does happen, use some solder wick to draw up the excess solder to clear the short. A magnifying glass will be handy here to inspect your work. Note that pins 6-9 and 10-11 are connected together anyway, so solder between these pins is OK. Once the IC is in, you can install the link beneath it on the other side of the board. This link must sit flat against the board, otherwise the board will not sit down in the case correctly. The remaining surface mount components – Q1, Q2, LED2 & REG1 – can Resistor Colour Codes (Receiver) o o o o o o o o No.   4   2   2   2   1   2   1 48  Silicon Chip Value 10kW 2.2kW 1kW 680W 220W 100W 10W 4-Band Code (1%) brown black orange brown red red red brown brown black red brown blue grey brown brown red red brown brown brown black brown brown brown black black brown 5-Band Code (1%) brown black black red brown red red black brown brown brown black black brown brown blue grey black black brown red red black black brown brown black black black brown brown black black gold brown siliconchip.com.au The assembled PC board clips neatly into a standard plastic utility case. The full installation and setting up details for the receiver will be in Pt.2 next month. now be soldered in place. Transistor Q1 has an N1 label on its top, while Q2 has an N2 label instead. These numbers relate to the MMBT100 and MMBT200 types respectively. Don’t get them mixed up. Installing the semiconductors The orientation of the two transistors is obvious – they have one pin on one side of the body and two on the other side. REG1 has a GND tab plus IN and OUT pins that must be soldered to the PC board. The central pin between the IN and OUT pins is left unconnected. Be careful with the orientation of LED2 – its cathode lead is the longer of the two. Next, solder in switches S1 & S2, then install five PC stakes for the ICSP header. These pins are inserted from the non-copper side of the PC board and soldered in position. The pins are then trimmed on the copper side to 3mm in height. On the underside, they are trimmed and filed to 0.5mm. The standard components can now be installed. These must be mounted flat against the PC board or as close to it as possible in the case of the 10kW resistor that straddles Q2. Take care with the orientation of diodes D1 & D2 and note that the tops of the three monolithic capacitors must be no more than 4mm above the PC board. In particular, the two capacitors near REG1 can be laid over at about 45°, while the one adjacent to IC1 needs to have its leads adjusted so it can be pushed down onto the PC board siliconchip.com.au far enough to meet the 4mm height requirement. Cut all the leads beneath the PC board (ie, on the non-copper side) flush with the surface. LED1 can go in next. Its anode lead is the longer of the two (unlike LED2) and this lead must go towards IC1. To mount it, first bend its leads down by 90° exactly 2mm from its body, then insert the leads into the PC board. Finally, push the LED all the way down onto the PC board, solder the leads and cut them flush with the underside. Note that a small circular notch is required in the rim of the keyfob base for the LED to sit in. This can be made using a small rat-tail file. When this notch has been made, file a matching notch in the top half of the keyfob case. Battery terminals The battery terminals are installed by first placing the PC board in the base of the case. That done, the terminals are slid into position and soldered. Make sure that the terminal with the spring is located as shown in Fig.3. Switch cover modifications The key switch covers that are supplied with the keyfob case have to be modified to suit the two switches on the PC board. As supplied, the two switch covers are already secured in place in the keyfob lid. This assembly must be removed and the covers carefully ground down to 1.5mm thick – see Fig.5. This is done by placing some 180-grit sandpaper onto a flat bench and sanding the switch covers until they are flat on their base. That done, cut out a 20 x 24mm rectangular piece from a silicone TO-3 washer (20 x 24mm) to make a new switch cover assembly. It’s then simply a matter of attaching the switch covers to this washer using silicone sealant – see photo. Use the keyfob lid as a template to position the covers correctly. Receiver assembly Now for the receiver. As usual, start by checking the PC board for any defects. Check also that the hole sizes for the screw terminal blocks are correct and enlarge them if necessary. That done, check that the PC board fits inside the specified utility case. File the board edges to get it to fit if necessary but don’t file them too much, otherwise the board will not lock correctly into the wall slots. Fig.6 shows the assembly details. Install the wire link first, then install the resistors. The accompanying table shows the resistor colour codes but you should also check them using a digital multimeter. The diodes and the IC socket can go in next, taking care to orient each with the correct polarity. Follow these with the capacitors, again making sure that the electrolytics go in correctly. The three PC stakes for TP1, TP2 & TPG can then be installed. Depending on your requirements, LEDs 1 & 2 can either be mounted directly on the PC board or mounted October 2007  49 Frequently Asked Questions One question that’s often asked about rolling code systems is what happens if the transmitter is out of range and one of the transmit switches is pressed? Will the receiver still work when the transmitter is later brought within range and the button pressed again? This question is asked because the code the receiver was expecting has already been sent and the transmitter has rolled over to a new code. So how does the system get around this problem? The answer to this is that the receiver will acknowledge a signal that is the correct length and data rate but it will not trigger unless it receives the correct code. So if the signal format is correct but the code is incorrect, the receiver then calculates the next code that it would expect and checks this against the received code. If the code is now correct the receiver will unlock the door. If the code is still incorrect, the receiver calculates the next expected code and will do this up to 200 times. If none of these are correct, the receiver keeps its original code but it will not trigger. In fact, the only way to trigger the receiver after this is to re-synchronise it to the transmitter. Of course, a second transmitter will still operate the receiver (provided they have been synchronised in the first place). That’s because this transmitter has a different identity and a different code to the other transmitter. Automatic synchronisation Some rolling code transmitters systems offer automatic synchronisation if the transmitter and receiver lose sync. In these systems, the receiver includes a code “look-ahead” feature as described above but the number of look-ahead codes is usually limited to fewer than 200. What happens is that if the code is not recognised after all the look-ahead calculations externally and connected using wire leads. Be sure to mount each LED with its cathode lead (the shorter of the two) towards the lower edge of the PC board. Similarly, IRD1 can either be mounted directly on the PC board or connected using twin-core shielded cable (see diagram in Pt.2 next month). Trimpots VR1 & VR2 and the 3-way and 2-way pin headers for LK1-LK4 50  Silicon Chip have been made, the receiver changes its synchronisation method. Basically, the receiver requires two separate transmission codes before restoring correct operation. On the first transmission, it calculates the next code it should receive using this received code as the basis for calculation. If the second code sent by the transmitter is the same as the code that was calculated, the receiver operates. The drawback of this latter scheme is somewhat less security since, in theory, two successive transmission codes could be intercepted and recorded. These codes could then be re-transmitted to synchronise and thus trigger the receiver. Calculating the code Another question that’s often asked is how does the receiver know which code to expect from the transmitter, since this changes each time? The answer to this is that the transmitter and the receiver both use the same calculation to determine the next code. They also both use the same variables in the calculation and these variables tend to be unique values that no other transmitter uses. For example, if the calculation for consecutive codes requires the original calculated code to be multiplied by 100 and the number 7 added to it, then both the transmitter and receiver will use these numbers to perform the calculation. Without knowing both the multiplier and the increment value, it would be very difficult to predict the next code. This is particularly true because of the very large numbers involved. The values quoted for the multiplier and increment value are not as simple as 100 and 7 but are 24 bits and eight bits respectively in length. In addition, the code length is 48 bits with as many as 2.8 x 1014 combinations. This reduces by a factor of 200 because of the look ahead feature to a 1 in 1.4 x 1012 are next on the list. That done, install REG1 and transistors Q1-Q4. Q1 & Q2 must be installed with their metal faces towards IC1. Finally, complete the board assembly by installing switch S1 and the screw terminal blocks. Note that the 6-way terminals at the righthand edge of the PC board are made up using three 2-way blocks. These are joined by sliding their dovetail joints chance of striking the correct code – still impossibly long odds. Code scrambling A further complication with the transmitted code is that the code is not necessarily sent in sequence. There are also 32 possible scrambling variations that can be applied to the code. What if the transmitter sends two consecutive codes that are the same and the code is intercepted and re-transmitted to open the lock? This is highly improbable and our rolling code transmitter has safeguards to prevent the same code appearing twice in succession. For each code calculation, a comparison is made between the current and last code. If the code is the same, the code is recalculated after an increment of the code value to ensure successive code calculations diverge. It is this new code that is transmitted. The receiver performs the same recalculation so that the new code will be accepted. Another question concerns the use of different transmitters. Does each transmitter use the same rolling code calculation and if so, wouldn’t the receiver lose its synchronisation if several transmitters were used? The answer is that the receiver will not lose synchronisation, even if one of the transmitters is not generally used. This is because each transmitter operates independently from the others. Only 16 transmitters can be used with a given receiver and each must have its own different identity from 1-16. The identity is built into each transmitter and synchronisation is required for each transmitter. The codes sent by each transmitter are different and the code includes the transmitter identity value. The receiver has 16 different rolling code and calculation parameters, and so each transmitter is treated independently. together before installing them on the PC board. That’s all we have space for this month. Next month, we’ll complete the construction and describe the installation and setting-up procedures, including setting the entry and exit delays. We’ll also describe the optional SOIC adapator board, so that you can program the PIC microcontroller out SC of circuit. siliconchip.com.au Wireless Weather Station This weather station has an unbeatable range of features, it is great value, and best of all no need for messy wiring. The system measures and displays inside & outside temperature, air pressure, rainfall, humidity, wind speed, direction, and chill factor. More Weather Stations • Requires 5 x AA batteries In-store • Indoor display: 140(W) x 170(H) x 40(D)mm Wi-Fi Internet Radio Listen to over 10,000 radio stations. There is no software to load, no complex set-up operations and no need to be a PC expert. Simply plug it into the mains power and turn on! The radio will automatically link into the existing Wi-Fi network and uses your broadband connection to access the Internet Radio Gateway. It's as simple as that. • Supports real audio, MP3 and Windows Media streams • Unit measures 250(L) x 130(W) x 140(H)mm Cat. YN-8069 $299.95 Note - This product requires an existing wireless network via a broadband router. Cat. XC-0293 $149 KIT OF THE MONTH PIC Based Logic Probe Ref: Silicon Chip Magazine October 2007 Unlike ordinary logic probes, this one is driven by a PIC processor and operates over a wide supply voltage of 2.8VDC to 5VDC. It is extremely compact and uses surface mount devices on a PCB only 5mm wide. The probe includes a 'pulse stretcher' that will let you see very short pulses and a latch function to 'hold' infrequent pulses. Kit includes PCB and all specified electronic components including pre-programmed PIC. You'll need to add your own case Cat. KC-5457 and probe - a clear ballpoint pen $14.95 and a needle work well. CAMPBELLTOWN STORE NOW RE-LOCATED 1/50 Queen St, Campbelltown, NSW. Phone: (02) 4620 7155 • Massive 250sq metre store • Easy access off street parking • Only 2 blocks from our old store FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 PLUG-IN LCD ELECTRONIC TARIFF METER / LOG This unit simply plugs into a domestic power socket. Any mains appliance, 10A or less, then can plug into it. The meter, when set, will display: the line voltage, line current and power of the appliance plugged in. It can also do this in other ways, such as peak, total time operating, accumulative etc. It can also display mains frequency, power factor, etc as well as how many $$ you are spending when you input the electricity tariff, both on and off peak! This unit is handy to use if you have to temporarily sell power on e.g. at a campsite. It will obviously also tell you just how much that old electric radiator is actually costing you to run! It is quite accurate, too. • Max. load: 10A, 2500W • Voltage Range: 210-301VAC • Current Range: Cat. MS-6115 0.02-10A • Freq range: 45-65Hz $39.95 • Battery: 2 x 1.5V LR44/AG13 For full specs see our catalogue or website USB DVD Maker Turn your VHS video tapes into exciting video productions or record live video straight to your DVD or CD burner. Editing software lets you add effects as well as sound tracks and titles to your work. • Requires PC with suitable burner Cat. XC-4809 $99 5.8GHz Wireless A/V Sender Wireless LAN, Bluetooth,cordless phones, etc, can cause overcrowding and interference for items that transmit on the 2.4GHz band. Beat the congestion with this 5.8GHz unit and ensure crystal clear reception no matter what audio video device you choose. Complete with built-in IR remote control repeater, AV leads, power supplies and instruction manual. • Additional receivers AR-1841 $159.95 Not C tick approved Cat. AR-1840 $249 Experimental Cube Eco Catastrophes Simulate earthquakes, tsunamis, pollution, floods, erosion, crude oil spills and more. Comprehensive colour instruction booklet describes all the experiments. Fun and educational. Suitable for ages 8+ 6 titles to choose from! Cat. KJ-8830 $29.95 REMOTE CONTROL MINI M.A.S.H. HELICOPTER This is our smallest ready to fly infrared remote control Mini Helicopter. This model is made of durable plastic and is ideal for indoor use. • Twin rotor • 15m IR remote • Suitable for 8 years+ • 20 min charge time for 8 min flying time • Throttle, rudder and stability controls • Requires 6 x AA batteries Cat. GT-3260 • Helicopter 180mm long Not to scale $29.95 Better. More Technical INTERNET> www.jaycar.com.au 1 Active Matrix TFT Security Monitors These rugged, high performance TFT monitors are purpose-built for security applications and include a toughened front panel to protect the TFT panel from damage. They can display up to the maximum resolution defined by CCIR standards (720 x 576 / 525 x 625TV Lines) via the incorporated I/P (interlaced to progressive scan) converter. See website for full specs. Two models available: QM-3419 17" Version QM-3420 19" Version Dont confuse with cheaper, non-protected LCD screens!!! Cat. QM-3419 $499 Non-Contact Infrared Door Exit Switch NEW 5.8GHZ WIRELESS CAMERAS This infrared sensor can replace the old push button switch on automatic exit doors so that they will open with just a wave of your hand. The sensor will trigger an internal relay when your open hand comes within 100mm of the panel. The sensor is mounted on a stainless steel plate and has indicator LEDs built in to signal that the switch has been activated. •12VDC supply voltage Cat. LA-5187 •3A <at> 30VDC contact rating $49.95 •30mm sensor diameter •70 x 115mm plate dimensions Economy 4 Channel Multiplexing DVR Toughened Glass Protected Screen Cat. QM-3420 $599 Video IP/Network Web Server - 2 Channel Upgrade your CCTV system to an IP (Internet Protocol) surveillance system. The unit can be given a fixed, or router assigned IP address, which allows camera images to be viewed and controlled from anywhere in the world via an Internet browser. See website for full details. $199 360° Pulse Count PIR This motion detector employs an omnidirectional infrared sensor and a reliable electronic circuit to provide reliable 360° intruder detection. • Power: 9 -16VDC • Size 110(dia.) x 44mm Cat. LA-5041 $149 Dual Beam Infrared Barrier Protect your doors or Dual Beams windows monitor door or with this window dual beam openings infrared detector. It's housed in a strong aluminium case and is suitable for outdoor use in protected environments. The detector will sound an internal buzzer & energise a relay when the beam is broken or tampering is detected. Mounting hardware included. Close up • Indoor sensing range 16m, of sensor 8m outdoors • 10 - 30 VDC powered Cat. LA-5186 • Sold as a pair $149 • Length 570mm D.I.Y. 2 Cat. QC-3570 Wireless CMOS Camera with 4 Ch Receiver $269.95 Plugpacks for both camera and receiver included. • 25(L) x 24(W) x 24(H)mm • Sensor: CMOS 628 x 582 pixels D.I.Y. Wireless CMOS Camera This camera is suitable as a spare, additional or replacement for our QC-3570 (shown above) Cat. QC-3571 5.8GHz wireless system. $179.95 A combined multiplexer and digital video recorder with Ethernet port that allows control via a web browser. Features MPEG-4 compression, advanced motion recording, covert recording, video loss detection, remote network record and back-up support. Supplied with a 250GB HD and can be expanded up to 400GB. See website for specifications. Cat. QV-3079 • 340mm wide • MPEG-4 compression $599 • 250GB HDD included 3.5” FIELD MONITOR FOR SECURITY CAMERA INSTALLERS Cat. QC-3394 Avoid the clutter on the 2.4GHz band with these 5.8GHz cameras and receivers. The system has a range of about 100m (clear line of sight) and also has audio capability. Plugpacks supplied. Not ACMA approved. Take the hard work out of camera installation with this portable video monitor. The unit connects to the camera being installed and lets you adjust and align the camera on your own, while you are still up the ladder. The monitor also has a 12 volt output so you can set up the camera even before the cabling is installed. Very handy. Includes: • Protective leather case with belt clip & shoulder strap Protective • Video cable Leather to suit BNC connections Case • Camera power cable Cat. QM-3421 $299 4 Input USB Video Recorder This is a surveillance device that allows you to record 4 camera inputs at the same time on a PC. It connects to the computer's USB 2.0 port and makes real-time monitoring a breeze. Four composite video inputs to accept any camera. Variable frame rate with instant or scheduled recording. • Single/four screen display mode • Camera ID, date & time display CMOS IR Camera with 4 Ch Receiver $299 This system's camera has an IR illuminator for low light and night use. • 78(L) x 45(Dia) x 83(H)mm • Sensor: 1/3" CMOS 628 x 582 pixels Wireless CMOS Camera with IR Illuminator Suitable as an additional or spare camera for our QC-3572 or QC-3570 (shown above) camera/receiver systems. • 78(L) x 45(Dia) x 83(H)mm • Sensor: CMOS 628 x 582 pixels Cat. QC-3573 $199 Wireless IR CMOS Camera Suitable as a spare or additional camera to suit: QC-3572 or QC-3570 camera/receiver systems. • 41(L) x 35(W) x 39(H)mm • Sensor: CMOS Cat. QC-3575 628 x 582 pixels $169.95 Pan Tilt Day/Night Vision Camera System with Hand Held Monitor 2.4GHz Wireless Is small enough to be carried and features audio, and an AV output for interface with a recording device. The 380TVL camera has an operating range of 100m (line-of-sight) and up to 5 metres night vision capability. Mains plugpacks are provided for both the camera and monitor. • Monitor size: 68(W) x 130(H) x 26.5(D)mm • Approx. camera size: 105(W) x 120(H) x 110(D)mm Remotely pan/tilt the camera from the hand-held monitor Cat. QC-3279 Cat. QV-3081 $399 $149 Better. More Technical Cat. QC-3572 FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 INTERNET> www.jaycar.com.au Digital Surveillance Event Recorder D.I.Y. Surveillance on a budget. It works by recording images to an SD memory card as JPEG or video AVI when motion is detected. View the events on a monitor or any media player that accepts SD cards. Two cameras are included with IR LEDs for low-light use, are housed in extremely robust aluminium cases and are mounted on ball swivel brackets. Cat. QV-3098 $349.95 Rear View Mirror TFT Monitor with Camera D.I.Y. A complete rear view safety package including a TFT monitor and a flush mount simple to install colour camera. It has adjustable spring-loaded brackets to fit different sized rear vision mirrors and includes a slimline remote control. Composite video input. Includes 5 metre video/power cable. Cat. QM-3762 • 7" screen • Simply clips over your $299 sun visor or rear vision mirror BIOMETRIC FINGER PRINT ACCESS CONTROLLER Protect your property with biometric technology for a fraction of the cost of other units on the market. One unit can be used to control a single door or access point, or multiple units may be used on a site and connected to a PC via RS232, RS485 or Ethernet connection. • Up to 500 users can be enrolled and each can have access restricted to certain times • ID speed: 1/4 - 2 seconds • Watchdog monitor • 12VDC 3A relay output • N/O or N/C door strike controls • Tamper and door ajar alarm outputs • Sleep mode to conserve power • RS232, RS485 or Ethernet comms • Power supply: 9VDC 500mA • Dimensions: 180(L) x 82(W) x 55(H)mm IP57 Pro Outdoor Colour Camera with Sony Super HAD CCD Sensor This camera is housed in a robust aluminum case and carries an IP57 rating. The Sony ® Super HAD sensor and the camera's 102 infrared LEDs enable the system to 'see' up to 50 metres in total darkness. Features include: • 1/3" Super HAD CCD sensor SENSOR INSIDE • 480 TV line resolution • 12mm lens Cat. QC-3381 $499 High Volume Wireless Door Bell with Strobe for the Hearing Impaired When this doorbell rings, the sound is accompanied by bright flashes from the receiver's built in strobe light so a hearing impaired person will know that someone is at the door. Can be taken from room to room and used outdoors. Choose from seven melodies. 210mm long. Requires 4 x C batteries. Cat. LA-5121 Cat. LA-5002 $499 $49.95 SECURITY CLEARANCE DVR Camera Kit with Colour Dome and IP56 Camera The DVR is fitted with a 250GB hard drive, can accommodate up to 4 cameras with power derived from the DVR and will allow you to record and view up to 4 cameras simultaneously. Package includes the DVR with a dome and outdoor IR camera with bracket, mounting hardware, power supply, 14m camera connect cable, software, USB interface lead & user Cat. QV-3085 manual. $949 Was $999 The 16 channel multiplexer and Ethernet connection make this DVR very versatile. It can be controlled and images viewed from any web browser. Includes video loss detection with event logging. Password protected. Full details on website. • 10/100 Base-T Ethernet connection • Digital recording with wavelet compression SAVE $500 SAVE $50 $999 Colour may vary Extra Colour Weatherproof IR Camera QC-3086 Was $199, Now $159, Save $40 Extra Colour Mini Dome Camera QC-3087 D.I.Y. Was $149, Now $119, Save $30 Shed/Garage/Boat Security Alarm Protect "The Shed" with this simple and reliable alarm. It consists of a main unit which houses a PIR for motion detection, and a loud piezo siren. A reed switch is included to place on the main door (or elsewhere). Installation is made easy, with the use of plugs and sockets for connections - no soldering or terminal blocks. It's powered by a mains plugpack (supplied), with the option of fitting 3 x AA batteries for backup power. Simple to install. Was $49.95 $39.95 SAVE $10 Colour CCD Smoke Detector Camera This unique camera is designed for covert, indoor surveillance applications and incorporates a CCD image sensor with a resolution of 380 TV lines. The camera is hidden inside a white plastic housing that looks like a smoke detector and is indistinguishable from the real thing. Cat. QC-3555 A microphone is SAVE $129 $40 also included. Was $169 Many more items on sale in-store * Note: Savings off Original RRP FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 INTERNET> www.jaycar.com.au This 380TV line camera SAVE $30 features a Sony HAD CCD sensor, flicker reduction technology, auto Cat. QC-3518 iris and auto white balance, back light compensation and operates on 12VDC $269 or 24VAC. • 160(L) x 52(W) x 48(D)mm Was $299 I N - S T O R E S A L E S O N LY ORRP $1499 Cat. QV-3074 Includes 250GB HDD Cat. LA-5400 Colour CCD Variable Focal Length Camera 16 Channel Multiplexing DVR with 250GB HDD CMOS Colour Flush Mount Camera - In Vehicle Ideal for large vehicles such as trucks, buses and trailers. Having a viewing angle of 150 degrees and supplied with both power and video leads combined within the one cable, this rear-view vision camera is simple to install and ready to plug directly into you monitor. Was $169 SAVE $30 Cat. QC-3451 $139 Colour 2.4GHz Wireless Video Door Phone Installation is a breeze with this wireless video door phone. The compact internal unit houses a clear 1.8" LCD, SAVE control buttons and can accommodate $100 up to 4 cameras which can be mounted up to 100m away from the receiver. The camera has IR illumination so you can identify Cat. QC-3625 who is at the door even in poor light. $399 Was $499 Better. More Technical 3 NEW PARTY SPEAKERS 12" 200WRMS Party Speaker This speaker provides good performance in difficult locations such as backyards, tents, party rooms or halls etc. Cat. CS-2514 Power handling: $210 200WRMS <at> 8 ohms. • Size approx 650(H) x 370(W) x 450(D)mm NEW CONTEMPORARY 12" Foldback LOOK! Speaker Rated at 300WRMS this 8 ohm wide range speaker is ideally suited for use as a foldback speaker on stage or as reinforcement in an existing system. • Enclosure Size: 650(W) x 330(H) x 440(D)mm Professional DJ's Direct Drive Turntable Purpose designed for professional DJ work, this excellent turntable packs a real punch and has all the features of more expensive turntables, plus a few extras of its own. Push button reverse, pitch adjustment, & track lighting, etc. Even Cat. AA-0495 has streaming digital and analogue $349 output. Noise Cancelling Folding Headphones These hi-tech wonders have a built-in noise cancelling circuit that reduces background noise by as much as 18dB. A fold-away design makes for easy storage and adaptors are included for airline use. Batteries included. Great value! Cat. CS-2516 $139 12" Subwoofer High performance subwoofer. Finished in durable heavy vinyl, the cabinet houses a 12” 4 ohm subwoofer rated at 300WRMS. Cat. CS-2518 • Enclosure Size: 480(W) x 580(H) $189 x 440(D)mm Moondot Revolving Disco Light Liven up any party with this funky light display. Featuring 18 high brightness red, green and blue LEDs that rotate, change colours and direction in response to music being played. Mains powered. • Measures 200 (L) x153(W) x 94(H)mm Cat. SL-2898 $99.95 Solar Powered LED RGB Ropelights This is the perfect outdoor lighting decoration and it doesn't need a power point. Just place the solar panel in direct sunlight and the system will switch on at night for a super light display. 6 lighting modes. Fully sealed for outdoor use. 2 lengths available 5 metres Cat. SL-2826 10 metres Cat. SL-2828 Cat. SL-2826 $49.95 Cat. SL-2828 $79.95 Cat. AA-2055 $59.95 AMAZING PARTY DEALS Great Sound Deal #1 INCLUDES: CAT. 2 x Party Speakers 15” 120WRMS CS-2515 1 x Stereo Amp 2 x 100WRMS with remote AA-0470 Total Value DEAL PRICE $449 RRP $358.00 $199.00 $557.00 Pictured Folded 7" TFT LCD Monitor Get ready for the party season with these fantastic deals Set the Mood Lighting Deal #2 INCLUDES: 1 x Fog Machine 1 x Fog Juice 1 x Party Lighting Set Mirror Ball & motor, PAR 36 Spot & coloured gels 1 x Moondot Revolving Disco Light Total Value CAT. AF-1214 AF-1212 RRP $79.95 $11.95 SL-2978 $69.95 SL-2898 $99.95 $261.80 SAVE $62.80 SAVE $108 In-Car Multimedia Player with Detachable Face This excellent unit will play DVDs, VCDs, MP3s and has an AM/FM radio. Use a SD card or another media player via the mini USB port. The amplifier is rated for 45WRMS per channel and features composite video, line-level audio and sub-woofer outputs. Fits a standard DIN opening, and includes mounting hardware. Supports DVD, CD, VCD, SD, USB • Full function remote control supplied • Dimensions: 182(W) x 169(D) x 53(H)mm D.I.Y. Cat. QM-3785 DEAL PRICE $249.95 $199 Produces NEW RESPONSE CAR 550W AMPLIFIERS when This new range features insert-typebridged. connectors, pass through RCA outputs, variable high and low pass filters and variable bass boost. See website for full specifications. 4 x 100WRMS Full Range Car Amplifier • 4 x 130WRMS <at> 4 ohms • 4 x 190WRMS <at> 2 ohms • 2 x 380WRMS <at> 4 ohms 4 D.I.Y. A truly versatile monitor with low power consumption, wide viewing angle and NTSC and PAL compatibility. Use it to watch DVDs, PS2, XBOX, etc. Use with flush mount reversing camera for a complete rear view safety package. • High resolution wide screen format • Includes remote control • Requires digital TV tuner for free to Cat. QM-3752 air viewing $179 Cat. AA-0456 5 Channel Full Range Car Amplifier • 4 x 60WRMS + 1 x 225WRMS <at> 4 ohms • 4 x 90WRMS + 1 x 340WRMS <at> 2 ohms • 2 x 180WRMS Bridged <at> 4 ohms + 1 x 340WRMS <at> 2 ohms $399 • 1 x 1000WRMS <at> 1 ohm • 1 x 600WRMS <at> 2 ohms • 1 x 1800WRMS <at> 2 ohms linkable Cat. AA-0460 Cat. AA-0458 $399 $499 Better. More Technical 1000WRMS Monoblock Amplifier FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 INTERNET> www.jaycar.com.au 1950s Style CD Player & Turntable 2.4GHz Wireless A/V Sender/Receiver Modern features with classic styling from with Infrared Remote the 50s, combining a turntable, AM/FM radio and CD player. The turntable has 33 and 45 RPM speeds and is automatic. The CD player has all the features you'd expect including repeat and memory functions, and will also play MP3 formats. Cat. GE-4068 $149.95 Features a phase-locked loop (PLL) electronic circuit that constantly adjusts, locking onto any input signal and avoiding any reception drift. Send stereo audio and video pictures around your home, shop or office, allowing you to watch video or listen to hi-fi quality stereo sound anywhere. All without the need to run cables. The refreshing new compact design incorporates the 2.4GHz dipole antenna and has 4 selectable channels. AR-1845 Additional Receiver $59.95 HDMI SOLUTIONS HDMI Leads and Accessories Cat. AR-1844 $69.95 RADIO RECEIVERS SLASHED Short Wave Stereo Receiver AM/FM Radio Receiver AM/FM/SW with LCD and Clock This multi-band pocket radio has digital tuning and has a large backlit LCD. It features full clock functions with an alarm and receives AM, FM and SW. • Dimensions: 110(H) x 65(W) x 20(D)mm • Requires 4.5VDC plugpack or 2 x AA batteries Was $29.95 SAVE $15 Cat. AR-1741 This is a fantastic way to show off your digital images or movies. You can have multiple images in a slide show, a single image, or thumbnails. You can also play a backing music track or show video clips. Supports SM, SD, Cat. QM-3765 XD, MS & MMC card formats. $179 • Display size: 150(W) x 85(H)mm See website for full specs • 10” also available QM-3768 Black QM-3769 White Both $299ea Satellite Finder Hi-Gain Indoor Digital VHF/UHF TV Antennae 4 Way HDMI Multimedia Splitter Connect a High Definition HDMI device to up to four displays. Cat. AC-1696 These indoor digital TV antennae have a built in amplifier with variable gain. The amplifiers are fitted with a 1.5m long TV-Out cable that is terminated with male F-connector. The Cat. LT-3132 units operate from $39.95 a 12V mains adaptor that is included. • Both approx 180(W) x 180(D)mm TWO MODELS 28dB variable gain LT-3132 36dB variable gain LT-3134 Cat. LT-3134 Cat. LS-3300 $49.95 $29.95 Refer: Silicon Chip July 2007 The primary function of this versatile project is to protect your expensive speakers against damage in the event of catastrophic amplifier failure such as a shorted output transistor. In addition, the circuit also banishes those annoying thumps that occur when many amplifiers are switched on or off, especially when the volume is set to a high level. The design also incorporates an optional over temperature heat-sensor that will disconnect the speakers if the output stage gets too hot. Configurable for supply voltages between 22VDC - 70VDC. Supplied Cat. KC-5450 with a silk screened PCB, relay and all $29.95 electronic components. KITS TO BUILD Subwoofer Controller Kit Refer Silicon Chip August 2007 Using this kit to control your external speaker and sub-amplifier can give you loads of bass without taking up much space. The kit has all the features you could want, including low and high pass filters, parametric equaliser and auto-turn on for external equipment. The controller is 12 volt DC powered and can also be used in automotive applications. Cat. KC-5452 • Kit supplied with silk screened $99.95 PCB and processed panels. FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 Standard Australian/NZ GPO mount with single or double HDMI sockets for AV installations. • Single - Cat. PS-0285 $14.95ea • Double - Cat. PS-0286 $24.95ea $79.95 7" Electronic Photo Frames Speaker Protector Kit MKIII HDMI Wall Plate Sockets Cat. AR-1746 $14.95 This is an absolute must for portable system like those in RVs. This is an instrument to make dish aiming a snap! Find satellites fast with our satellite finder and save countless hours of frustration as you try to align your dish. This attractive stereo receiver has a cool blue LED backlight which features 9 pre-settable stations at the push of a button, full clock functions, headphone output jack, and an LED power and stereo indicator. With a sturdy handle and a SAVE $20 massive 925mm telescopic antenna you can be assured of the best reception any where. Was $99.95 High definition multimedia interface (HDMI) provides high quality signals for the best in reproduction quality. Male to Male Connection WQ-7400 1.5m $39.95ea WQ-7402 3.0m $49.95ea WQ-7404 5.0m $64.95ea WQ-7405 10m $99.95ea HDMI to DVI Cable WQ-7406 3.0m $39.95ea HDMI Adaptors PA-3640 HDMI Socket to Socket $14.95ea PA-3642 HDMI Plug to DVI-D Socket $14.95ea PA-3644 HDMI Plug to DVI-D Plug $14.95ea INTERNET> www.jaycar.com.au $299 Supports HDCP compliant devices and 720 or 1080p resolution. It accommodates up to a 5m length cable, has a single link range of 1920 x 1200 and a vertical frequency range of 60Hz. Plugpack included. Home Theatre Powerboard Surge protection and filtering are provided for the mains power to all your equipment and further protection is provided by the in-built circuit breaker. Cat. MS-4024 This powerboard also has telephone protection, data protection for a $59.95 network connection, satellite/cable TV video protection, and protection for TV aerials. Stereo VU/Peak Meter Refer: Silicon Chip May '07 Accurately monitors audio signals to prevent signal clipping and ensure optimum recording levels. This unit is very responsive & uses two Short form kit. 16-segment bargraphs to Case sold separately display signal levels and transients peaks in real time. There are a number of display options to select, and both the signal threshold and signal-level calibration for each segment are adjustable. Kit supplied with PCBs, LCD and all electronic components. Accuracy within 1dB for signals above -40dB. Cat. KC-5447 • Requires 9V-12VDC power supply $69.95 use: MP-3147 $17.95 • Case not included use HB-6082 Better. More Technical 5 USB GADGETS USB Desktop Bouncer This tough looking guy with his cockney accent will turn away any would be punter trying to interfere with your desktop stuff. He'll warn them off with one of his six tough-guy quotes. •1.2m USB lead included • Can stand alone using 3 x AAA batteries Cat. GE-4088 • Stands 210mm $24.95 high USB Panic Button Hit your USB Panic Button and your screen instantly changes to a spreadsheet or other image that looks like real work. Use one of the image files included on the CD or your own screen shot. • Software and image files included • Dimensions: 90(L) x 48(W) x 52(H)mm These foldable speakers are compatible with all iPods® and most other MP3 devices and they produce excellent sound. • Folded 90(L) x 65(H) x 60(W)mm • Requires 4 x AAA batteries or 6V DC adaptor Cat. XC-5186 • iPod® not $29.95 included $24.95 USB Exercise Bike Mouse with LCD Word Counter USB Data Extension Cable Spare missiles to suit - pack of 3 sold separately GE-4073 Four USB 2.0 and three IEEE 1394 (Firewire®) ports make this a versatile hub. PC and Mac compliant. • Supports self-powered mode and bus-powered mode Cat. GE-4072 $49.95 Cat. GE-4073 $6.95 PCMCIA Fingerprint ID for Laptops Protect sensitive information on your laptop from unauthorised personnel with this fingerprint ID access control. It simply slides into the PCMCIA slot in your laptop and utilises biometric technology to identify authorised users of the computer. It also locks the computer under the screen saver and can be used for file/folder encryption. See website for specifications. $129 6 r See ounge hugh raod® of iP ories accesstore In-s Combined USB 2.0 and Firewire Powered Hub USB Missile Launcher Having a slow day at work or are there too many people bothering you? Sort them out with a missile launcher with realistic sound effects. Ready! Aim! Fire! • Pans 180° & tilts 45° • Connects to PC via USB port $199 Extend the length of your USB device by an additional 5 metres using this Active USB Repeater Cable. It meets USB Electrical Cat. XC-4839 and Timing specifications, defeating signal errors that you would experience $24.95 using an ordinary passive extension cable. Up to 5 of these cables can be joined. This hard working mouse will pedal one revolution and increment the counter each time you type a word on your keyboard. Loads of fun and great for essay writing, articles and projects etc. • 140mm high • Computer not Cat. GE-4086 included $24.95 Cat. XC-4843 Boasting composite, S-Video, component and RGB video output with stereo and digital (SPDIF) audio output, it is compatible with almost any home theatre system. With up to 500GB of hard drive storage (IDE HDD not supplied), you can keep a large library of movies and music on the device to entertain for days. PC connection is made easy with the USB 2.0 interface and supplied USB cable. The unit features a cool blue LCD and backlit control panel and is supplied with a slim line remote control that allows for full playback functions, zoom and slideshow control. Cat. XC-4866 The stand allows for vertical mounting. iPod® / CD / MP3 Foldable Speakers with Cradle Cat. GE-4091 Constructed of foam. MPEG4 Media Player with Remote Control Everything you would expect from a modern network attached storage device and more! Includes a built-in BitTorrent client that can be used to download and share files over the BitTorrent network without the need to have your computer turned on. • Full specifications on our website. Cat. XC-4677 $199 USB Keyboard Video Monitor (KVM) Switches KVM switches allow you to connect multiple computers to one keyboard, mouse, and monitor. You can then select between computers using keyboard hotkeys or push buttons. 2 PORT Cat. YN-8091 4 PORT Cat. YN-8092 Cat. YN-8092 $139 Cat. YN-8091 $89 Microsoft Windows Vista An Ultimate Guide This book discusses all five versions of Windows Vista and guides you through installation, setup and trouble shooting. • Includes practical tips & hints • Soft cover 364 pages 197 x 130mm • Also available soft cover 384 page book called Using Microsoft Windows Vista Media Centre. Cat. BB-7105 $29.95 12V Notebook Power Supplies Cat. XC-4848 $69.95 External 3.5" HDD Cases for IDE or SATA Drives Add gigabytes of storage to your PC or move large files from work station to Cat. XC-4664 work station with ease. This HDD case $49.95 is made from strong aluminium & will accommodate a 3.5" hard drive. Supplied with plugpack, software and USB interface lead. • Size: 117(W) x 183(D) x 50(H)mm BLACK EXTERNAL 3.5" HDD CASE - SATA Cat. XC-4666 $79.95 Folding Keyboard This dual layout (QWERTY/DVORAK) keyboard has a folding cover that protects it when not in use and doubles as a rest for your wrists as you type. The best value for money dual layout we have seen! Better. More Technical NAS Device with Built-in BitTorrent Client They have a 12 to 13.8V input voltage, feature a recessed voltage selector to eliminate accidental changes to the selected voltage, high efficiency, low power consumption, LED power indicator and are supplied with 7 output connectors for all major laptop brands (see website or in-store for listing). • Terminates to a fused 10 amp automotive cigarette lighter socket Cat. MP-3463 15/16/18/19/20/ 22/24VDC $34.95 <at> 3.5 AMPS MP-3463 15/16/18/19/20VDC <at> 6 AMPS 22/24VDC <at> 5 AMPS MP-3467 Cat. MP-3467 $47.95 Portable Hard Drive Enclosure with Fingerprint Security & Data Encryption Portable hard drives allow easy mobile data storage but can make confidential information vulnerable to embarrassing disclosure. This drive case prevents this by using onboard fingerprint recognition and encryption software to secure the data on the drive. 125mm long. USB powered. Hard drive not included. Cat. XC-5153 $39.95 Cat. XC-4668 $99 FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 INTERNET> www.jaycar.com.au DRIVE A FERRARI TODAY! Remote Control Cars These 1/10 scale factory endorsed Ferrari replicas will amaze you. The detail is fantastic. They have operating (LED) headlights and tail-lights, and independent front & rear suspension. The best finished model cars we have seen. • Pistol grip remotes, rechargeable battery pack, mains charger and 9V battery included • Suitable for ages 10yrs+ Cat. GT-3210 (27MHz) RC Mini Mosquito Helicopter with LEDs This chopper looks like a mosquito and has green LEDs for eyes. It is just as easy and fun to fly as our other RC Mini Helicopter. Fast, fun and stable, just hit the throttle and off it goes. • 15m IR Remote • Suitable for 8yrs+ • 30 min charge time for 10 min flying time • Throttle, rudder and stability trim controls • Requires 9V battery • Mosquito 170mm long Cat. GT-3262 $59.95 Remote Controlled Mini Helicopter The twin rotor design of this chopper makes it very easy SAVE to fly and $10 very stable. The infrared remote unit has a range of about 15 metres and has throttle, rudder and stability trim controls. It recharges in about 20 minutes from the remote unit, giving about 8 minutes of flying time. • Requires 6 x AA batteries • Remote: 130(L) x 120(W) x 45(D)mm Cat. GT-3215 • Helicopter: 170mm long, weight 10g $39.95 • Suitable for ages 8+ Was $49.95 SCIENCE EXPERIMENTS - KITS FOR KIDS! Experimental Cube - Mysteries of Nature Explore the mysteries of nature in a practical way that is easily understood by young minds. Includes 25 experiments from water filtration to the formation of lunar craters. Colour instruction book and required equipment is included. • Suitable for Cat. KJ-8826 ages 8+ $29.95 Cat. GT-3212 (40MHz) Cat. GT-3214 (27MHz) Short Circuit Explorers - Electricity Cat. GT-3210 $69.95 Cat. GT-3212 $69.95 Cat. GT-3214 $69.95 IR Remote Control Horse Racing Game Have your own Melbourne Cup or Kentucky Derby in your lounge room. Set up your track and pick a nag, then race to the finish. Each horse runs on all four legs and can be trimmed left or right. The horses have rechargeable batteries and charge from the remote control units in about 20 minutes. Track Cat. GT-3240 size: 1200(L) x 600(W)mm. Each charger $99.95 requires 4 x AA batteries. SPARE HORSE WHITE - CH 4: GT-3242 SPARE HORSE SPARE HORSE BLACK - CH 3: GT-3244 $49.95 Eclipse Battery Bulk Packs Eclipse Alkaline Battery Bulk Packs - mercury & cadmium free. SB-2331 24 x AAA SB-2330 24 x AA SB-2332 40 x AA SB-2417 6 x 9 Volt Cat. SB-2330 $12.95 Cat. SB-2331 $12.95 Conduct your own exploration into the science of electricity. Design a burglar alarm, work with circuitry and switches. With over 17 projects, find out how batteries really work while Cat. KJ-8800 learning about lightning, $ 19.95 conductors and insulators. • Suitable for ages 8yrs+ The Human Body Explore your senses with a range of experiments that will help you understand more about yourself and how your body works and reacts with the world. • Suitable for ages 8+ Cat. KJ-8828 $29.95 Short Circuits Explorers - Inventions in Music This kit will take the young musician on a captivating journey from learning the fundamentals of tempo, beat, and rhythm to building and playing simple instruments. Includes a recorder, kazoo, and basic parts to make a range of instruments including a guitar, tambourine, drum, and even a rain stick. Cat. KJ-8816 $19.95 More kits in the range to choose from 153 Experiments in Electricity and Magnetism Kit Learn all the basic principles behind electricity. 153 different experiments to keep the junior mad scientist occupied for hours without burning the house down. All the experiments require only a 9V battery or no power at all. • Ages 9+ Cat. KJ-8835 $39.95 Open & Closed LED Message Display Have your business noticed with this illuminated LED 'Open' or 'Closed' sign. It displays the equivalent of a 40 x 196 dot matrix with ultra high intensity LEDs. The 'Open' illuminates in red and the Closed' in yellow. • Size: 400(W) x 117(H) x 50(D)mm Shocking Number Guessing Game With two separate games of number guessing and Simon Says you're guaranteed hours of fun. Have as many people you like play along but beware! The person who eventually guesses the correct number or gets the Simon Says sequence incorrect will cop a mild electric shock. • Requires 3 x AAA batteries • Base measures 120mm Dia. Cat. GH-1134 $24.95 Remote or PC Controlled Moving Message Display Display specials, opening hours or prices for your passing trade, or just display the time with this attention-getting display. It can be programmed with the remote control unit or with a PC via the RS-232 interface. Mounting bracket, remote unit, software and RS-232 cable included. Wall mounting Cat. XC-0193 • 50 x 7 LED dot matrix $169.95 • 435(L) x 97(H) x 37(D)mm Cat. XC-0191 Cat. SB-2332 $19.95 Cat. SB-2417 $89.95 $13.95 FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 INTERNET> www.jaycar.com.au Better. More Technical 7 The Amazing Flygun Thousands Sold It is a spring powered gun that kills Every Month flies and mosquitoes! It's fun, safe, and easy to use. You can become a hunter in your own home! A one metre long string is attached so the swatter doesn't fly away, you can then reload, aim and fire again. It's fun and effective, and Cat. YS-5545 really does work! $7.95 Suitable for ages 8+ yrs. Solar Powered Sonic Pest Repeller Cat. YS-5532 $29.95 Thermal Insect Bite Reliever Reduces pain and inflammation from minor insect stings and bites. Simply apply directly to the bite area for relief from mosquito bites, sand flies and ants. • 120(L) x 26(dia)mm • Requires 2 x AA batteries • Caution: This is not a medical device and should only be used for relief from minor insect bites. Featuring 10 high brightness LEDs and internal rechargeable batteries that are charged by the solar panel on the handle. Leave it basking in the sun during the day for a light filled night. • Solar panel measures 120(L) x 28(W)mm • Torch 210mm long Cat. ST-3077 $24.95 Digital Thermometer for Fridge or Freezer No more spoiled food. This thermometer will set off an alarm when your fridge or freezer goes above or below set temperatures. • Mounting hardware included • Requires 1 x AAA battery • 67(W) x 39(H) x 15(D)mm Cat. QM-7209 $16.95 Cat. YS-5536 $19.95 The indoor receiver measures the indoor temperature, humidity, atmospheric pressure and receives weather data from Cat. XC-0330 the outdoor wind sensor $249.95 and rain gauge. The receiver unit has a USB interface output allowing data to be uploaded to a PC or laptop. The XC-0332 unit has an additional AV output so you can view the weather data on your TV. Mains adaptor and software See our full supplied. range of See Weather Stations website for In-store full details. 8 Cat. SL-2715 10 LED Solar Powered Torch Keep the mozzies away while everyone else gets eaten alive. With a range of 6 metres, it's perfect for camping, picnics fishing etc. It also has a pocket or belt clip to keep it handy. Cat. YS-5534 • Requires 1 x AA battery • Measures: 75(L) x 25(dia)mm $7.95 $299 Ideal for garages, gazebos and greenhouses. The 360° adjustable solar panel will allow for custom positioning. It's waterproof, features a cord-switch to operate, and is simple to install. Pack includes solar panel and mounting bracket, 2.4m cable and rechargeable enclosed Ni-Cd battery. Great gift idea for campers or hikers. Just one minute of winding will give you 30 minutes of light. Approximately 130mm long. $19.95 Personal Sonic Insect Repeller Cat. XC-0332 Solar Powered Garage LED Light Cat. ST-3337 Solar powered so you never need batteries or it can be powered from a 3VDC plugpack (not included). This sonic pest repeller helps keep undesirables at bay. 3 different frequencies for different pests mozzies & fleas, mice & rats, cockroaches. • Belt clip • 2 year guarantee • 80(W) x 95(H) x 35(D)mm Computer Interface Weather Stations Dynamo Wind up LED Torch $39.95 Solar LED Outdoor Umbrella Light Provide light at any time for your outdoor setting. The solar panel screws onto the top of the pole to charge during the day and connects into the light fixture via the 1m power lead included. • Light dimensions 200(Dia.) x 59(H)mm Simply place them on the ground to warn other motorists and guide them around a problem. The lights have three bright LEDs that can be easily seen from a distance. They are made from tough plastic and have two Cat. ST-3185 lighting options, steady and flashing. • Requires 2 x AAA batteries $9.95 • Size: 90(dia) x 25(H)mm BBQ Fan with AM/FM Radio and LED Torch This three blade BBQ fan is perfect for keeping the smoke and heat away from you or to keep you cool on hot summer days. It also features a radio, LED torch, timer and alarm clock. The fan connects to a long flexible goose-neck that can be clamped to almost anything. • Requires 4 x C batteries and 1 x AG10 battery Cat. AR-1783 $9.95 Water Powered Calculator Powered by a tiny electrolytic cell smaller than a AA battery, this nifty calculator runs entirely on water. Just fill the cell with a few drops from the tap. One top-up lasts about a month. • 105(L) x 77(W) x 12(D)mm $39.95 BBQ BUDDIES These two little marvels run on water, so no need for batteries, solar or mains power. Simply fill up the two clear plastic tubes and they will start to work in seconds. Easy to set up and will never run out of power. Two models available. • AR-1781 Round - 140mm wide • AR-1783 Square - 75mm wide $19.95 Cat. ST-3293 Breakdown & Emergency Road Flasher Water Powered Clocks Cat. AR-1781 Ideal for when there is no mains power available Cat. GG-2308 $49.95 Stainless Steel Flexible BBQ Lamp This outdoor light is made from rust-resistant stainless steel and is battery powered. It is fitted with 25mm clamping jaws and 480mm gooseneck so that it Cat. SL-2806 can be attached to whatever is handy, be it table, fence or BBQ. $29.95 • Requires 4 x AA batteries Cat. QM-7276 $9.95 Better. More Technical FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 INTERNET> www.jaycar.com.au SAVE ON SHORT DISTANCE COMMUNICATIONS 38 Channel 1.5 W UHF Pocket Transceiver SAVE $30 This high-quality light-weight UHF transceiver is ideal for use in many professional and leisure activities. Up to 8km working range with a hi/lo setting to conserve power. Was $89 Cat. DC-1040 $59 38 Channel UHF Radio • 500mW power • Up to 5km range • Compact & easy to use $34.95 UHF Twin Pack Walkie Talkies This pack of 2 funky mini UHF CB communicators can keep you clearly in touch up to 3km. They feature electronic volume control, monitor functions and an integrated blue LED torch. Cat. DC-1005 • Requires 3 x AAA batteries per unit. $49.95pr See our full range of CB Radios in-store IR SMS Messenger Communicators Send and receive text messages with these fantastic IR communicators. No mobile phone and no bills! The devices are lightweight and can be clipped onto your belt. They feature discrete text notification as well as a calculator, calendar and a clock with alarm. The transmission range is 4.5 metres with maximum of 10 metres. • Size: 85(W) x 30(D) x 90(H)mm Cat. GE-4240 • Sold as a pair $29.95 • Requires 3 x AAA per unit d! s Sol sand Cat. KC-5195 $14.95 Simply strap the Pulse Walker to your arm and keep track of your walking, heart rate and calories burned. It also has a clock, timer, calendar and alarm. Battery included. Other Models In-store $24.95 Rechargeable Work Light The strong magnetic mount, twisting handle and hanging hook allows you to complete those hands-free operations. Cat. ST-3024 • With two lighting options, 1 Watt LED or 30 LED's. $39.95 • Mains and 12V chargers included Economy Car Alarm An economy alarm that has many of the advanced features you would normally only expect to find on more expensive systems. Fantastic value. Includes • Electronic black box controller • Shock sensor • Ignition cut-out relay • Wiring Cat. LA-9000 looms $89 If you love cars you'll love this fantastic wireless doorbell. Choose between a thumping V8, a Formula-1 racer, or motor bike and get your heart pumping every time the doorbell rings. If that gets too exciting you can switch to a sedate ding-dong while you recover. Cat. LA-5000 30m range. Requires 3 x AAA batteries. $29.95 V8 Alarm Clock Wake up to the realistic V8 engine-sounding alarm. Easy to use and attractive in design, it is sure to be a hit with any motoring enthusiast young or old. • Realistic pedals for demo and clock controls • Spinning brake disc when the alarm is activated • Clock 120mm dia. • Requires 3 x AA batteries Cat. AR-1769 $24.95 12V Rechargeable LED Light Wall mounted or portable, this handy light has a multitude of uses, from the garden shed or workshop to camping, boating or the caravan. It has a built-in 4Ah battery with a 12V DC charging socket, power and charge LED indicators and a test button. Wall mounted or portable. Cat. ST-3170 • Charging time: 16 - 18 hours $29.95 • 290(L) x 78(W) x 82(H)mm Combined Wireless Reversing Sensor and Tyre Pressure Monitor This reversing sensor will alert you to obstacles behind your car and show the distance to it. Also shows the pressure and temperature of your tyres. Also detects slow leaks and over-temperature. Fully automatic. Cat. LR-8865 $399 Smart Fuel Mixture Display Kit Adaptive Turbo Timer Kit Refer: Silicon Chip August 2007 Ordinary turbo timers with a fixed time setting don't adapt to engine use and can turn off too early if the car has been driven hard, or run your engine overtime if the car has only been pottering about. This excellent kit overcomes the problem by constantly monitoring engine load and adjusting the timer run-time to suit the turbo's cooling need. Maximum cool down can be adjusted from a few seconds to 15 minutes and the timer will automatically work within this range. Indicators show when the Cat. KC-5451 timer is in operation, cooling period, and sensor level. Kit supplied with silk screened PCB and all $44.95 electronic parts. FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 Cat. XC-0273 Wireless Doorbell with V8, F-1, Bike, or Ding-Dong Sound KITS FOR CARS Refer: Silicon Chip November 1995 This very simple kit will allow you to monitor the fuel mixtures being run by your car. This type of sensor is also known as an E.G.O. (exhaust, gas, oxygen) monitor. You can use it as a tuning tool, to help in vehicle modification or simply to see the behaviour of the engine control module. Indication is via 10 LEDs to show mixtures rich, lean and normal. The circuit connects to the EGO sensor mounted in the exhaust manifold and the cars battery. • PCB, LEDs and components supplied. Thou This unit gives full VHF channel coverage of all international VHF marine channels. The antenna is removable so it can be connected to a larger antenna mounted on a boat. Features adjustable squelch, belt clip, high/low output selection. • Charging cradle and 12VDC plugpack included Cat. DC-1094 • 5W, 56 channels • Frequency rage: 156MHz - 162MHz $199.95 • 100 x 55.5 x 31mm Spare battery to suit - only $29.95 Cat. DC-1095 Pulse Walker Pedometer with Heart Rate Monitor Cat. DC-1010 Mixture Display Kit For Fuel Injected Cars 5W Marine VHF Transceiver INTERNET> www.jaycar.com.au Refer: Performance Electronics for Cars This kit features auto dimming for night driving, emergency lean-out alarm, and better circuit protection. Another great feature is the 'dancing' display which operates when the ECU is operating in closed loop. Kit supplied with PCB and all electronic components. • Car must be fitted with air flow and EGO sensors (standard on Cat. KC-5374 all EFI systems) for full functionality. $27.95 Better. More Technical 9 NEW THIS MONTH Digital Stem Thermometer Indispensable around the house, workshop or lab. Data hold, min/max memory, Cat. QM-7216 auto shut-off and stainless steel probe. Battery included. $19.95 • Measures: 205mm long IP67 LED Modules Endless possibilities - backlighting signs, strip lighting in stairwells & passageways, boats, garages etc. Supplied with 3 LEDs per module, 10 modules, with 500mm flying leads for termination. Each module is spaced at approximately 110mm between centres. Simply connect up a 12VDC 600mA supply and away you go. Two types: •ZD-0490 10 x 3 LED Module White (total 30 LEDs) •ZD-0492 10 x 3 LED Module Blue (total 30 LEDs) • Adhesive backed for quick installation • Waterproof and submersible Cat. ZD-0490 • IP67 rated $19.95 • Resin sealed • Brightness per LED: Cat. ZD-0492 White: 1200 - 1500mcd Blue: 600 - 800mcd $19.95 • Each module: 47(L) x 17(W) x 6(H)mm Total length: Approx. 1m LED spacing: 15.6mm PCB Holder with Magnifying Glass Anytime you need that extra bit of help with your PCB assembly, this pair of helping hands will get you out of trouble. With a 90mm magnifying glass, it also provides an extra pair of eyes. Cat. TH-1983 • Size: Base: 78 x 98mm $12.95 • Height: 145mm 1000V 7 Piece Screwdriver Set GS and VDE tested and approved. Soft rubber grip handles, with insulation right to the tip. CHECK THIS GREAT PRICE! Cat. TD-2022 $19.95 Save 35% on this Fantastic Tool Package! Enjoy Electronics but always looking for the right tools? This Electronic Hobbyist Tools Deal gives you everything you need at a great price! Deal includes RRP 1 x Digital Multimeter QM-1320 $34.95 1 x Soldering Kit TS-1650 $19.95 1 x Screwdriver Phillips TD-2206 $4.95 1 x Screwdriver Slotted TD-2201 $4.50 1 x Precision Screwdriver Set TD-2017 $11.50 1 x Long Nose Pliers TH-1888 $15.95 1 x Side Cutters TH-1886 $15.95 1 x Crimp Tool TH-1828 $6.85 1 x Tweezers TD-2122 $5.85 1 x IC Extractor TH-1818 $2.00 1 x Nibbling Tool TH-1768 $19.95 1 x Toolbox with Storage Lid HB-6327 $9.95 Total Value $152.35 DEAL PRICE $99 Refer: Silicon Chip July 2007 This simple circuit illuminates a string of LEDs to quickly indicate the water level inside a rainwater tank. The more LEDs that illuminate, the higher the water level is inside the tank. Ten sensors located in the water tank and connected to the indicator unit via light-duty figure-8 cable provide the input signal. Kit includes PCB with overlay, machined case with screen-printed lid and all electronic components. • Requires: 2.5mm PVC hose/pipe Cat. KC-5449 (length depending on depth of tank) • Requires 12-18V AC or DC plugpack $34.95 PRECISION JAPANESE MADE CARBON STEEL TOOLS 125mm Precision Long Nose Pliers The pliers feature serrated jaws and a box joint to provide a precise action and strong grip. The coil spring ensures smooth, fatiguefree use. Insulated soft touch handles. These quality tools are made in Japan from the same High Carbon Steel that is used to make professional chef's knives Cat. TH-1885 $24.95 150mm Precision Side Cutters These cutters are designed for sharp cutting in precision wiring. They have insulated soft-touch handles and a coil return spring for fatigue-free use. Cat. TH-1891 $27.95 SAVE $53.35 CLEARANCE $AVINGS 10MHz Velleman Personal LCD Handheld Oscilloscope The Velleman Personal Oscilloscope is ideal for hobbyists, students, service people, automotive applications & general development. Features include high contrast LCD with wide viewing angle, full automatic setup for volt/div & time/div, true RMS and dB measurements, screen hold function; low battery detection Cat. QC-1916 and auto power off. Ask $349 in store for full details. OBD II LCD Scan Tool If you have a late model car, it will probably have an OBD (On-Board Diagnostics) connector. If it was manufactured after 1996, it will support the OBD II protocols. This OBD II Scan Tool supports the CAN (Controller Area Network) protocol and can be used to Can be diagnose prior to repair and used to check the VIN number on to verify a repair after late model cars! Cat. QP-2294 service. $129 Water Level Indicator Kit MKII 10 HOBBYIST TOOL DEAL Non-Contact Thermometer with Laser Sighting Measure the temperature of practically any surface with this easy to use portable instrument. It features wide temperature range, laser sighting, and an 8:1 distance to spot size for accurate sighting. Includes SAVE backlight, and belt holster. $18 Was $97.95 Cat. QM-7223 $79.95 Non Contact Voltage Detector This model features adjustable sensitivity so you can find live wires from more than 1 metre away, then gradually reduce Cat. QP-2276 the sensitivity to isolate $14.95 SAVE individual wires in a $5 bundle. Was $19.95 Waterproof Digital Thermometer with Flexible Probe Provides fast and accurate temperature readings Cat. QM-7229 on the LCD screen. Easy SAVE $11.95 to use and will store the $8 last temperature taken • Auto off • 150 long Was $19.95 KITS TO BUILD USB Experimenter's Interface Kit 10A 12VDC Motor Speed Controller Kit Refer: Silicon Chip June, 1997 Use this kit for controlling 12V DC motors in cars such as fuel injection nds Sold pumps, water/air intercoolers and water Thousa injection on performance cars. You can also use it for headlight dimming and for running 12V DC motors in 24V vehicles. The kit will control loads up to 10 amps, although the addition of an extra MOSFET transistor will double that capacity to an amazing 20 amps. Cat. KC-5225 • Kit includes PCB plus all electronic $23.95 components to build the 10A version. • Extra MOSFET available separately, ZT-2450 $7.80 Better. More Technical Interface your computer to the real world. There are five digital and two variable gain analogue inputs. Eight digital and two analogue outputs are available. Supplied with all components, silk screened PCB, assembly manual and Cat. KV-3600 software. $69.95 FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 INTERNET> www.jaycar.com.au Laptop Power Supplies You can take this power supply anywhere in the world. • 7 selectable DC voltages • 10 adaptor plugs for most popular brand power supplies: Apple, Dell, Compact, Acer, HP, amongst others • Great for travelling as it takes both 110V & 240V • 15/16/18/19/20/22 <at> 3.5A, 24<at>3.0A • Power LED indicator Cat. MP-3461 • Over current protected $49.95 • 144(L) x 63(W) x 38(H)mm MP-3465 5A Power supply also available separately $79.95 WIND GENERATORS 200 Watt Wind Turbine Generators 12V and 24V models available. They will generate 200 watts at wind speed as low as 8 metres per second and will deliver useful power with a gentle 3 metre/sec breeze or give up to 300 watts at higher wind velocities. Features a 3 phase permanent magnet alternator with 2.1 metre diameter 3 blade rotor and new solid state regulator with auto detection of battery voltage to control charge levels. The units will withstand wind speeds of 40m/sec (144km/hr). Some skill is required in construction e.g. concreting, mechanical assembly and rigging. Units are shipped in 2 boxes, with a combined weight of 65kg. NB. Due to the weight and size not all stores will have these in stock. The store can order the New unit for you & have improved solid it delivered to your state control site (freight costs box are additional). See website or Both Types (ea) catalogue for $499 further specifications. Dual Stage Lead-Acid Battery Float Chargers Four Pack Ni-MH Rechargeable Batteries Fully automatic switchmode battery chargers that will efficiently charge high capacity sealed and unsealed lead acid batteries then properly maintain them. Just connect and forget. 12V <at> 6A $79.95 Cat. MB-3610 12V <at> 12A $99.95 Cat. MB-3612 24V <at> 6A $99.95 Cat. MB-3614 Modern digital devices require high current high drain performance cells. These high capacity batteries will provide the best in portable power. SB-1738 2500mAh AA $19.50 SB-1735 2400mAh AA $15.95 SB-1737 2000mAh AA $13.95 SB-1739 900mAh AAA $11.95 1/2 Hour Rapid Battery Charger Fast charge 4 x AA or AAA Ni-Cd/ Ni-MH batteries in just 30 minutes! Microprocessor controlled with LED charge indicators, fan assisted cooling, and individual charging slots. SAVE Was $59.95 $10 $49.95 2 Hour Fast 240VAC Battery Charger This rapid 2 hour fast charger is designed specifically for Ni-MH AA or AAA batteries. Recharges individual or up to four batteries and will switch automatically to trickle charge to avoid overcharging and damaging the battery. • Auto selects the correct charge for AA or AAA batteries • Plugs directly into 240V mains, SAVE general purpose outlets $15 Was $39.95 NEW DC - DC CONVERTERS Cat. MB-3541 24 - 12V DC-DC Converters DC to DC converters are useful for running 12V devices from a 24V supply in a truck or bus. These have switchmode technology for light weight and compact design, and come in a range of current ratings up to 40 amps. 10 AMP Cat. MB-3513 $24.95 160(L) x 48(W) x 48(H)mm Cat. MP-3061 iPod Replacement Battery Kits ® Whilst iPods are incredibly popular the lithium rechargeable batteries locked inside only have a fairly limited number of charge/discharge cycles. Once the battery starts to fail the iPod® performance falls off quickly. The replacement battery comes with special tools and instructions to safely open and reseal an iPod®. Generations of iPods® covered: Mini®, 1st, 2nd, 3rd, 4th generation, Shuffle®, Nano® and iPod® Videos. Cat. MP-3061 $59.95 ® 20 AMP 210(L) x 90(W) x 50H)mm Cat. MP-3063 Cat. MP-3063 $99 40 AMP 188(L) x 190(W) x 70(H)mm Cat. MP-3066 Cat. MP-3066 12V Model $149.95 Cat. MG-4512 24V Model Cat. MG-4510 MORE KITS TO BUILD Fast Ni-MH Battery Charger Kit Refer: Silicon Chip Magazine September 2007 A truly versatile charger, capable of handling up to 15 of the same type of Ni-MH or Ni-Cd cells. Build it to suit any size cells or cell capacity and set your own fast or trickle charge rate. It also has overcharge protection including temperature sensing. Ideal for R/C enthusiasts who burn through a lot of batteries. Kit includes PCB & all specified electronic components. Heatsink, case & battery holder not included. Cat. KC-5453 $39.95 Generation 1st/2nd 3rd 4th Mini Shuffle Nano 1st NEW MODELS Nano 2nd Video 30GB Video 60GB Cat. SB-2570 SB-2572 SB-2574 SB-2576 SB-2578 SB-2579 RRP $19.95 $19.95 $19.95 $19.95 $18.95 $18.95 400 580 850 SB-2580 SB-2575 SB-2577 $24.95 $24.95 $29.95 Battery Zapper Kit MKII Refer: Silicon Chip May 2006 Like its predecessor this kit attacks a common cause of failure in wet lead acid cell batteries: sulphation. The circuit produces short bursts of high level energy to reverse the damaging sulphation effect. Kit includes machined case with screen printed lid, circuit board, alligator clips & all electric components. Cat. KC-5427 • Suitable for 6, 12 and 24V batteries • Powered by the battery itself $99.95 FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 mAh 1600 850 900 500 300 300 INTERNET> www.jaycar.com.au 4 Outlet Powerboard with 5M Extension Cord This 4 outlet powerboard features an integrated cable reel which stores its 5m extension cord. Featuring surge protection and an on-board illuminated power switch it is portable, easy to store Cat. MS-4042 and can be rolled out at $29.95 a moments notice. Kit Powertool Battery Charger Controller Refer: Silicon Chip Dec 2006 Cordless drills are fantastic and cheap, but really the batteries in them don't last with the simple charger supplied. This controller turns the cheap charger into a contractor grade intelligent charger. Suits both Ni-Cd and Ni-MH cells. Kit includes PCB with overlay, case, all electronic components. Better. More Technical Cat. KC-5436 $39.95 11 SOLAR PANELS 12V Powertech Polycrystalline Solar Panels 2 year manufacturer warranty and a 20 year warranty on efficiency! 12 Volt 4.5 Watt Solar Battery Charger Ideal for charging sealed lead acid batteries. This 12 Volt 4.5 Watt solar panel is tough enough to be walked on and can be mounted on a flat surface, or on its brackets so it can be moved to follow the sun. Great for use on a yacht or boat or in a car. • Voltage (max): 18V • Current (max): Up to 250mA • Panel Size: 187 x 255 x 17mm 12VDC TO 230VAC INVERTERS 12VDC to 230VAC Inverters Inverters are available from 150W to a massive 1500W. All have a LED power indicator, electrical isolation between the battery and secondary voltages for safety, and the higher power inverters feature fan assisted cooling. 24V inverters also available. MI-5110 Cat. ZM-9018 They feature tempered glass protection to ensure they are not easily damaged in the harsh environment which solar panels exist in. Each solar panel has an integrated waterproof junction box with cable glands. Cat ZM-9071 ZM-9073 ZM-9074 ZM-9076 ZM-9078 ZM-9079 Watts 5 10 20 65 80 120 Price $99.95 $149 $239 $549 $699 $1050 $99.95 20 Watt 12 Volt Solar Panel MI-5102 This top quality BP Solar 12 volt panel is rated at 20 watts and ideal for smaller power systems etc. They have a manufacturer's warranty of 10 years. See our website for our full Cat. ZM-9062 range of solar panels MI-5112 $269 Solar Power Controller Maintain your battery system in peak condition with this excellent charge controller. It features 30A capacity, temperature compensation, and full overload protection. Multi-mode operation. See website for details. 12V 6 Amp Solar Charging Regulator Compatible with all types of solar arrays and is water resistant. Disconnects the load during the day to ensure max power is directed to the battery. Will automatically block Cat. MP-3128 reverse current through the solar array. $229 4 Ni-MH Pre-Charged Rechargeable Batteries These feature ultra-low self-discharge technology so they can be used immediately after purchase. 85% charge retention after 1 year, case included. SB-1752 AAA 1.2V 800mAh SB-1750 AA 1.2 V 2000mAh Cat. SB-1750 $24.95 Cat. SB-1752 $14.95 YOUR LOCAL JAYCAR STORE Australia Freecall Orders: Ph 1800 022 888 NEW SOUTH WALES Albury Ph (02) Alexandria Ph (02) Bankstown Ph (02) Blacktown Ph (02) Bondi Junction Ph (02) Brookvale Ph (02) Campbelltown Ph (02) Erina Ph (02) Gore Hill Ph (02) Hornsby Ph (02) Newcastle Ph (02) Parramatta Ph (02) Penrith Ph (02) 12 6021 9699 9709 9678 9369 9905 4620 4365 9439 9476 4965 9683 4721 6788 4699 2822 9669 3899 4130 7155 3433 4799 6221 3799 3377 8337 $39.95 Cat. MP-3124 Silverwater Sydney City Taren Point Tweed Heads Wollongong VICTORIA Coburg Frankston Geelong Melbourne Ringwood Springvale Sunshine QUEENSLAND Aspley Cairns USB Rechargeable Ni-MH AA Batteries These 1450mAh AA size batteries simply plug into any powered USB port to be recharged. They're a brilliant idea for battery operated PC input devices such as a mouse or keyboard. They have an incorporated LED charge status indicator, and they can also be recharged by any Cat. SB-1755 250mA Ni-MH charger. • Pk 2 $17.95 Ph Ph Ph Ph Ph (02) (02) (02) (07) (02) 9741 9267 9531 5524 4226 8557 1614 7033 6566 7089 Ph Ph Ph Ph Ph Ph Ph (03) (03) (03) (03) (03) (03) (03) 9384 9781 5221 9663 9870 9547 9310 1811 4100 5800 2030 9053 1022 8066 Ph (07) 3863 0099 Ph (07) 4041 6747 Better. More Technical Modified Sine Wave type Cat No MI-5102 MI-5104 MI-5106 MI-5108 MI-5110 MI-5112 MI-5114 MI-5114 Power 150W 300W 400W 600W 800W 1000W 1500W Price $48.95 $79.95 $139.95 $229.95 $269.95 $359.95 $529.95 150W Inverter with USB Outlet This compact (150mm long) inverter plugs directly into your vehicle's cigarette lighter socket to deliver 230VAC at Cat. MI-5125 150 watts. The modified sinewave unit comes with a USB port to $79.95 charge or power your MP3 player or other USB operated device. Can Sized 150W 12VDC to 230VAC Inverter Designed to fit cleanly into your car's drink holder, this can sized inverter alleviates the need for permanent mounting of your inverter and avoids having it flapping around on the passenger seat only to go flying to the floor when you hit the brakes. Ipswich Ph (07) 3282 5800 Mermaid Beach Ph (07) 5526 6722 Townsville Ph (07) 4772 5022 Underwood Ph (07) 3841 4888 Woolloongabba Ph (07) 3393 0777 AUSTRALIAN CAPITAL TERRITORY Belconnen Ph (02) 6253 5700 Fyshwick Ph (02) 6239 1801 TASMANIA Hobart Ph (03) 6272 9955 SOUTH AUSTRALIA Adelaide Ph (08) 8231 7355 Clovelly Park Ph (08) 8276 6901 Gepps Cross Ph (08) 8262 3200 WESTERN AUSTRALIA Maddington Ph (08) 9493 4300 Northbridge Ph (08) 9328 8252 FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 Cat. MI-5121 $49.95 NORTHERN TERRITORY Darwin Ph (08) 8948 4043 NEW ZEALAND Christchurch Ph (03) 379 1662 Dunedin Ph (03) 471 7934 Glenfield Ph (09) 444 4628 Hamilton Ph (07) 846 0177 Manukau Ph (09) 263 6241 Newmarket Ph (09) 377 6421 Palmerston Ph (06) 353 6738 Wellington Ph (04) 801 9005 Freecall Orders Ph 0800 452 9227 Prices valid until October 31st 2007 INTERNET> www.jaycar.com.au SERVICEMAN'S LOG Fix it in the carpark! Ever tried to fix a rear projection TV set in a carpark? That’s precisely the silly situation I got myself into recently, all driven by a terrible need to earn money. I was asked to go and fix a Sony TV in someone’s garage. Well, I have been asked to do weirder things than that before but I gently pointed out that it would be easier (and hence cheaper) if he brought it in. My client apologised but said it just wouldn’t fit in his van and he couldn’t lift it by himself. How large could this set be? It turned out to be 154cm (61inch) rear projection TV measuring 1336 x 1519 x 647mm (W x H x D) – no mere portable! The set was, in fact, a 1997 Sony KPE61SN11 (SCC-K64C-A RG-1 chassis). Its problem was that it took hours for a picture to come on. But why was it in the garage? Simple – it wouldn’t fit into his tiny flat! The other major drama was that he lived near the sea. Why is that a drama? Well, this set generates 34kV and supplies it to three picture tubes at up to 3mA. And that often means insulation problems. siliconchip.com.au Anyway, reluctantly, off I went to this guy’s small garage at the back of his unit. However, in order to gain the necessary access, we had to first pull the TV out of the garage so that I could work on it in the carpark. This was, at best, quite unsatisfactory. I switched the set on, hoping that the voltage drop on his incredibly long extension cord wouldn’t have any effect! The set tried hard to come on but in the end just the red LED was left flashing. Unfortunately, this set was too old to have meaningful error codes that could actually be read. Initially, I tried disconnecting the EHT to the HV block splitter but it made no difference. There was no point persisting in the carpark – I removed the power supply and called it quits. Back at the workshop, I examined the power board and discovered that pin 3 (-135V) of socket CN6010 was corroded and pitted. I cleaned this up, Items Covered This Month • Sony KP-E61SN11 (SCCK64C-A RG-1 chassis) rear projection TV set • Sony KV-HX32M31 TV set (AX-1 chassis) • Sony KV-HR32M31 TV set (AX-1 chassis) • Grundig Lenaro 92 TV set (MFW92-6110/9 DVD CUC1937 chassis) soldered a few suspect dry joints and replaced C6030 (0.039mF 1kV) which is on pin 3 of T6005. I also replaced R6009 and R6010 (270kW) – both startup resistors – as they were corroded. Next, I connected a 100W globe across the +135V rail and shorted +7V STBY (pin 1) to Power Control (pin 3) of connector CN6008. I then connected 240V AC directly to CN6007 and the power supply came on quickly and cleanly, to give the correct voltage outputs. Convinced that I had fixed the power supply, I returned to the set. However, it wasn’t going to be that October 2007  63 Serviceman’s Log – continued easy. This time, the set made a better effort to start up and with the HV unit disconnected, was able to give a healthy spark for a moment or two. But then it would close down and the LED would flash. This time, I decided to take the horizontal deflection panel (E) with me, plus the convergence board (D), the latter also carrying the vertical output IC. Back at the workshop, I carefully examined each board, cleaning and soldering dry joints as well as replac- ing any component that looked even slightly suspicious. That done, I replaced the vertical output IC (IC1501, STV9379) and resoldered the convergence output ICs. I also thoroughly checked the protection circuits on the E board and checked the flyback transformer for shorted turns. Having done all that, I was optimistic that everything would now be OK. However, I also took a new HV unit with me on this my third attempt to fix the set in-situ. I cannot tell you how difficult it is to service a large TV in the middle of a carpark, out in the open. Unfortunately, despite being sure that these three boards were now OK and having installed the new HV unit, I still hadn’t made any real progress. I did manage to check the main voltages but was then forced to abandon the whole exercise when another unit owner wanted to park her car. Finally, I fronted up to the client and told him that it had to go to the workshop or nothing more could be done. Fortunately, he could see the sense in this and said he would arrange for it to be delivered. When it arrived, I got stuck into it and found that the set was trying hard to come on but just wasn’t making it. I then decided to unplug large chunks of circuitry until it stabilised itself. This took some time and there wasn’t much left connected when I finally disconnected the focus lead from the flyback transformer. That turned out to be where the problem lay and with everything else reconnected, the CRTs began at last to light up and the sound came on. Now that I knew where the fault lay, I played around with the focus and G2 control assembly but soon came to the conclusion it was “shot”. I then ordered and fitted a new one and the set behaved a lot better but it still wasn’t completely fixed. In particular, Looking for real performance? NOT A REPRINT – Completely NEW projects – the result of two years research & development • Learn how engine management systems work • Build projects to control nitrous, fuel injection and turbo Fro m the pu blis he rs 160 PAGES 23 CHAPTE RS of boost systems • Switch devices on and off on the basis of signal frequency, temperature and voltage • Build test instruments to check fuel injector duty cycle, fuel mixture and brake and coolant temperatures • Speedo Corrector, Turbo Timer & Digital Thermometer Projects Intelligen t turbo timer I SBN 095 852 9 7809 5 294 - 4 8 5229 4 $19.80 (inc GST) TURBO B OOST & ni trous fuel 6 NZ $22.00 (inc GST) controllers How eng in manageme e nt works Mail order prices: Aust. $A22.50 (incl. GST & P&P); Overseas: $A26.00 via airmail. Order by phoning (02) 9939 3295 & quoting your credit card number; or fax the details to (02) 9939 2648; or mail your order with cheque or credit card details to Silicon Chip Publications, PO Box 139, Collaroy, NSW 2097. 64  Silicon Chip siliconchip.com.au This LG plasma TV set look fine until it was switched on. The display had somehow been smashed internally, probably due to the set being knocked over. the picture was very poor, particularly on the blue gun. It took a long time before the penny finally dropped. It was the blue tube that was dragging down the focus voltage of the whole set and destroying the focus control and G2 assembly. I removed the blue CRT socket and disassembled it completely. And once inside, the problem was self-evident. The focus spark gap assembly had become completely corroded, causing arcing and shorting everywhere inside the CRT socket (Part No. 1-251179-21). Ironically, the red and green CRT sockets were totally unaffected. The old HV unit was also faulty, as it was arcing from fine carbon “varicose veins”. I have now decided that the logistics This is what happens to a magnetron when the fan cooling isn’t working effectively. The melted cooling fins are clearly visible. are just too difficult in handling these huge sets – especially when all the electronic circuitry is just 80-100mm above the ground and access to the underneath is appalling. I doubt that I will try fixing any more of these monsters in the future – although hunger may force me to change my mind. LG plasma TV Take a look at the photo at top left of this page. It shows an LG plasma set that looks fine when it is switched off but shows amazing colours when on. The display is smashed internally. Panasonic microwave A Panasonic microwave oven came in unable to cook. The overworked and underpaid technician quickly diagnosed the magnetron as the culprit and fitted a new one. Now all magnetrons look very similar and their part numbers are also very similar and often interchangeable. Essentially, magnetrons vary only in their power output and type of fastening. Our bloke stuck this magnetron in and checked it for its ability to boil water in the specified time. Everything tested OK and the oven was returned to its owner. About a month later, the oven was returned with the same complaint and our technician performed the rework. Sure enough it was the magnetron again but why? Eventually the penny dropped. The replacement magnetron he had fitted was incorrect. The mounting screws are 90° out which meant that New Low Cost Colour Oscilloscopes! Price performance breakthrough! Colour oscilloscopes with USB & PC Software. e Pric ugh! o thr eak Br siliconchip.com.au Prices start from a low $895! *Educational discount available. info<at>triosmartcal.com.au October 2007  65 Serviceman’s Log – continued when it was fitted, the fan was unable to blow onto the cooling fins of the magnetron. This in turn resulted in it overheating and melting – see photo. Sony HD TV sets Although it’s always been a problem, the number of jobs that now end prematurely for financial reasons is on the increase. Most service companies charge for the time taken to produce an estimate of the cost of repairs but unless you actually complete that repair, you cannot do better than a wild guess. This particularly applies if one fault masks another. I had two separate cases recently involving the Sony AX-1 chassis. These sets are barely out of warranty and are 1080i HD CRT TVs with all the bells and whistles, and cost around $3000. The first was a KV-HX32M31 and even a causal glance at all the AV plugs and sockets on the rear revealed large quantities of corrosion and rust. This set had spent a lot of its life close by the beach – in fact, if it had been any closer it would have been giving surfing lessons. The insides of the set were just as bad, with every metal surface now coloured brown with rust. When the set was switch­ ed on, it went straight into protection mode with the red LED flashing three times. This indicated a B+ overvoltage (OVP) problem. My first step was to remove the deflection and main-power supply board (D). This showed extreme corrosion everywhere – even the resistors were rusting! A few quick measurements soon revealed that R6512 (1W) – a feed resistor for the +135V rail – was open circuit. Replacing it made the error code change to four flashes which means “Vertical Deflection Stopped” Radio, Television & Hobbies: the COMPLETE archive on DVD YES! NA R MO E THA URY ENT QUARTER C NICS O OF ELECTR ! Y R O T IS H This remarkable collection of PDFs covers every issue of R & H, as it was known from the beginning (April 1939 – price sixpence!) right through to the final edition of R, TV & H in March 1965, before it disappeared forever with the change of name to EA. For the first time ever, complete and in one handy DVD, every article and every issue is covered. If you’re an old timer (or even young timer!) into vintage radio, it doesn’t get much more vintage than this. If you’re a student of history, this archive gives an extraordinary insight into the amazing breakthroughs made in radio and electronics technology following the war years. And speaking of the war years, R & H had some of the best propaganda imaginable! Even if you’re just an electronics dabbler, there’s something here to interest you. • Every issue individually archived, by month and year • Complete with index for each year • A must-have for everyone interested in electronics Please note: this archive is in PDF format on DVD for PC. Your computer will need a DVD-ROM or DVD-recorder (not a CD!) and Acrobat reader (free download) to enable you to view this archive. This DVD is NOT playable through a standard A/V-type DVD player. Exclusive to SILICON CHIP ONLY 62 $ 00 +$8.80 P&P HERE’S HOW TO ORDER YOUR COPY: BY PHONE:* (02) 9939 3295 9-4 Mon-Fri BY FAX:# (02) 9939 2648 24 Hours 7 Days <at> BY EMAIL:# silchip<at>siliconchip.com.au 24 Hours 7 Days BY MAIL:# PO Box 139, Collaroy NSW 2097 * Please have your credit card handy! # Don’t forget to include your name, address, phone no and credit card details. 66  Silicon Chip BY INTERNET:^ siliconchip.com.au 24 Hours 7 Days ^ You will be prompted for required information siliconchip.com.au (V-Stop). I replaced the vertical output IC (IC5101, STV9379A) but this made no difference. By this stage, I had already decided that I would have to quote for a new board. It wasn’t cheap but the client accepted the estimate and a new board dutifully arrived and was installed. This time the set came on but it was arcing inside the picture tube which was down to air. I examined the tube very carefully but couldn’t see any holes or cracks in the glass but it was definitely cactus. Unfortunately, a 76cm HD flat widescreen CRT costs as much as a new set so that was the end of the job. To be fair, the customer took the news well but it all cost us a motza. Apart from all our wasted time, there was also the restocking fee for the board when it was returned to Sony, so we were well out of pocket. Ironically, the second set, a KVHR32M31, arrived not long after the new board had been returned. Its fault was that it was giving an error 10 code which means “high-voltage stopped” (HV-PROT). The deflection and power circuits for this set are similar to that of a computer monitor (which it can be), except that the picture tube is much bigger. I would have to say that it is one of the most complex sets I have ever had the misfortune to service. I noticed that by jiggling the G2 adjustment on the flyback transformer, I could sometimes get a poor picture that could last from a few seconds to a few hours – even when the red LED siliconchip.com.au error code was still 10. As an experiment, I tried winding back the sealed HV Adjust pot (RV8002) but it made little difference to the symptoms even though it did vary the EHT, which was 31kV. The G2 voltage seemed to be the problem – it never rose above 100V. This was because it was being held down by a power transistor circuit (Q9014) on the CRT board (C) which is strapped across the G2 line via a 100kW resistor. This is called the “Power Mute Circuit” and I had never encountered it before. I assume that if the set develops an EHT fault, the microprocessor tries to reduce screen burn by removing the G2 voltage. In this case, I felt fairly sure that the flyback transformer was the problem and quoted accordingly. Once again, this was a very expensive spare part but the client was happy to pay. Unfortunately, when it was ordered and installed, it didn’t change a thing – the fault was still there. This was turning out to be yet another financial disaster, just like the last set. In the end, I decided that the cost – in labour and materials – could still be very open ended and so I decided to abort the job and cut our losses. Naturally, the owner was disappoint­ ed and I hate leaving it like this, especially as I am busting to know what is causing these faults. But as Dirty Harry used to say “a man’s got to know his limitations”. Out-of-focus Grundig Because of its size and weight, I agreed to do a service call on a 2002 Grundig Lenaro 92 TV set (MFW926110/9 DVD using a CUC1937 chassis). This must have been one of the last Austrian-built Grundigs before BEKO took it over and it cost about $7500. The complaint was that the focus was poor and then the set died. When I arrived, you couldn’t help but admire the enormity of this huge 92cm CRT console television set. This model also included a built in DVD and flash-drive MP3 player, not to mention a 6-channel 140W Dolby AC3 amplifier. This is all well and good but it meant removing a lot more stuff before I could access the chassis inside the cavernous TV cabinet – or should I say TV hall? Anyway, I eventually managed to slide the chassis out to get access to the dynamic focus panel. However, before I could finally reach the components I was after, I had to remove a plastic support panel, with all its clips and silicone rubber. The parts in question were two 1.5nF 6000V Wima capacitors in the focus accelerator. I replaced them with blue ceramic capacitors before tediously reassembling the whole thing. This turned out to be a disaster because when I finally switched the set on, it was still out of focus. I then tried adjusting the focus control on the accelerator panel but it was already at its end stop. In the end, I had to realign the focus control on the CRT board before it was all back to normal. SC October 2007  67 Simple Data-Logging Weather Station Part II – by Glenn Pure Last month, we introduced our new Rain and TemperatureMeasuring Weather Station, with all the electronics. This month, we get into the nitty-gritty of building it – all the mechanical detail and then the actual construction. B Y NOW, WE’VE HOPEFULLY WHETTED YOUR appetite with this simple design. Most of the mechanical detail here is “roll your own” but there is an alternative commercial rain sensor available if you don’t have the time or inclination to make one. For those who do . . . Making the rain sensor The rain sensor uses a tipping bucket mechanism, consisting of a rain collection funnel that feeds water into a pivoting bucket divided into two opposing halves. When one side of the bucket fills and tips, it empties itself, at the same time positioning the opposing side under the funnel 68  Silicon Chip outlet where it can fill, tip and repeat the cycle. The tipping back and forth can be detected in various ways. Since power consumption was important for this project, a passive sensing mechanism was chosen. This involves momentarily closing a switch each time the bucket tips. As shown in the circuit diagram last month (Fig.1), the switch closure pulls the rain sensor line low (it is normally held high by a 220kW pullup resistor). To keep the design simple and maximise reliability, I used a magnetic reed switch that is mounted on a bracket next to the tipping bucket. The switch is closed by a tiny rare- earth magnet (measuring only 3 x 2mm) that is mounted on the tipping bucket. As the bucket swings, the magnet moves past the reed switch, closing it for a brief moment. A similar mechanism is found in many commercial rain sensors and has the advantage that the reed switch is practically immune to moisture and corrosion, etc. To achieve its light weight and non-magnetic properties, the tipping bucket and its mount are made from 0.7mm thick aluminium sheet. You may well have some of this in your junk box, salvaged from those utility boxes that come with both an aluminium lid and a plastic one. siliconchip.com.au The main funnel is glued using silicone sealant into a 100mm PVC pipe end-cap which has its end removed. Note the mesh leaf and insect trap on the bottom end. The water then passes into a secondary funnel, mounted on a U-shaped bracket fixed to another (complete) PVC pipe end cap. You can see this end cap in the next photo. Under the secondary funnel is the tipping bucket mechanism which fills with water and tips when it gets too heavy. A magnet on the tipper trips a reed switch to indicate one “fill”. The only problem with using this sheeting is that it is work-hardened, making it difficult to bend and shape easily. This can be fixed simply by heating, which will anneal the aluminium and make it much easier to shape. I used a blow torch for maybe 10 or 20 seconds, with the flame constantly moving over the piece. Do not heat it so that it starts to glow. If you don’t have a blowtorch, try sitting the sheet on an electric stove (solid) hotplate for a minute or two. However, before annealing the sheet, mark out and cut the bucket according to the plan shown in Fig.4. For accurate cutting, use a utility knife to score the sheet repeatedly, then bend it back and forth along the score line to snap it (bending it only 10° or so each way is enough). Practice on a scrap piece – you will quickly get the idea. Next, very lightly score a line along the centres of the drill holes. Continue this line across the whole width of the sheet as it is useful later when centring and mounting the divider between the two halves of the bucket. Drill the holes now as it is a lot easier before the bucket is bent into shape. The holes for the axle in the tipping bucket should be very slightly larger than the axle and located as marked on the template. It’s important that the axle sits close (a millimetre or two) below the bottom of the main body of the bucket as this makes for more sensitive operation. Now, anneal the sheet then proceed to bend it into shape. Start by bending the bucket supports (containing the axle holes) back down against the body of the bucket. Keep the bend sharp, for example by clamping along the bend line in a vice. Next, shape the main body of the bucket by bending it over a tube or rod about 25-30mm in diameter. A broom handle works well, as does some 1-inch diameter PVC pipe. Make sure the result is symmetrical and even in shape, both lengthways and sideways. The aluminium should be quite soft and easy to reshape if necessary. Finally, cut a divider to separate the two halves of the bucket. The width of the divider will depend on the diameter of the rod used to shape the bucket. The divider is “glued” into place using a small amount of silicone sealant or epoxy. It’s a good idea to include narrow (3mm wide) right-angle flanges on the sides of the divider to help glue it in place (see template). Once the glue has set, smear a thin bead of silicone sealant along the edge of the divider, where it meets the inside of the bucket, to ensure water doesn’t flow from one half of the bucket to the other. A cotton tip from the medicine cupboard will do the trick. Minimise Here’s the way the magnet is mounted on the tipping bucket – it (or in some cases they) is (are) glued into this hole made in the side (top) of the tipping bucket. Another close-up of an important part: the plastic washer which stops the bucket mechanism fouling the mounting bracket. Without this, the readings may be erroneous. Once the bucket has tipped and the water measured, it needs to escape. These mesh-covered holes in the pipe end-cap are for that purpose. Note the measurement for the two screw holes. siliconchip.com.au October 2007  69 REAL VALUE AT $13.95 PLUS P & magnet hole (3.5mm) 4 axle hole cL 80 bend down 180o axle hole 28 45 outside width of bucket +4mm 32 bend to semicircle axle hole hole for tieing off cable to reed switch 15 65 P 4mm hole fold lines 25 30 12 Silicon Chip Binders 0.6-0.8mm aluminium sheet TIPPING BUCKET BRACKET TEMPLATE TIPPING BUCKET TEMPLATE bend flange 90 o to back flange 3-4mm end open divider on centre line (magnet) inside height of tipping bucket 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 12 issues & will look great on your bookshelf. H 80mm internal width H SILICON CHIP logo printed in gold-coloured lettering on spine & cover H Buy five and get them postage free! Price: $A13.95 plus $A7 p&p per order. Available only in Aust. Silicon Chip Publications PO Box 139 Collaroy Beach 2097 Or call (02) 9939 3295; or fax (02) 9939 2648 & 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: _________________________________ Card Expiry Date ____/____ Signature ________________________ Name ____________________________ Address__________________________ __________________ P/code_______ 70  Silicon Chip bend flange 90 o to front inside width of tipping bucket TIPPING BUCKET DIVIDER TEMPLATE (axle under) (axle) plan elevation end open TIPPING BUCKET ASSEMBLED Fig.4: follow this diagram to make the tipping bucket assembly for the Simple Data Logging Weather Station. the amount of silicone applied, but apply it to both halves of the bucket to better balance the two sides. The rare earth magnet can now be glued into the locator hole on the upper side of the tipping bucket. One more thing is needed to finish the tipping bucket. When it is in operation, it appears to empty more efficiently and consistently if the inside surface of the bucket is water repellent. This can be achieved by coating it with a silicone car polish. Don’t be tempted to smear a thin coat of silicone sealant as this tends to be sticky and collects fine particles over time, impeding the proper operation of the tipping bucket. The tipping bucket pivots on a thin axle. For this, a short length of stainless steel wire (1.4mm in diameter) was used, although galvanised steel wire would probably be fine. The diameter isn’t critical. The wire was obtained from the whisk part of a $2 stainless steel egg whisk. A bracket to mount the tipping bucket on its axle can now be made from another piece of aluminium sheet (don’t use steel sheet as it is magnetic). Again, drill the holes in this for the axle before bending. The exact dimensions of the bracket will depend on the width of the tipping bucket. Precision isn’t necessary since washers or spacers should be used to keep the tipping bucket away from direct contact with the bracket, ensuring an unimpeded tipping action. Such spacers (or washers) are also important to ensure minimum sideways play of the tipping bucket on the axle. Avoiding such play will keep the magnet on the bucket positioned a constant distance from the reed switch each time it swings past. A distance of about 3-4mm should be the target (face of magnet to centre axis of reed switch). Adjustment of the bracket to achieve the correct spacing is made by simply bending it. If the magnet is too close, the force of attraction between it and the reed switch can be sufficient to cause the tipping bucket to lock in centre position. If the gap is too great, the reed switch simply won’t close. The spacers can be cut from the end of the plastic ink tube of a ballpoint pen. The reed switch is glued to the outside of the bracket that holds the tipping bucket. Be warned that the part of the reed switch that is most sensitive to the magnet is either end of the switch, not the middle of it, so ensure the reed switch is mounted so the magnet swings past one end (see Fig.6). A separation of 3-4mm between the magnet and the reed switch is best. Care is needed when soldering wires to the reed switch since it appears to partly melt at soldering temsiliconchip.com.au MATERIAL: 0.4mm GALVANISED STEEL SHEET RADIUS 180mm RADIUS 12mm MAIN FUNNEL TEMPLATE (50% ACTUAL SIZE) Fig.5: these two templates will help you make your main (primary) and secondary funnels. The main funnel catches the rain, the secondary funnel directs it into the tipping mechanism. Note that the main funnel template needs to be blown up 200% when photocopying, otherwise it will be a tad too small! The overlap when you bend the funnel shapes should be about 8mm. Seal this overlap with silicone sealant. perature. Hence it is essential to use a good heatsink between the switch and the end of the wire being soldered (firmly gripping with a pair of needlenose pliers will achieve this). Once soldered up, the switch and connections should be covered with sealant to waterproof them since the connecting wires on the switch are made from steel and will corrode over time if they get wet. The tipping bucket is housed inside a length of 100mm diameter PVC sewer pipe. A rain collection funnel is fitted to the top end of the pipe. The funnel was made from thin (0.4mm) galvanised steel sheet (see Fig.5). After bending, it was held in shape with pop rivets then the join soldered up, although silicone sealant would be fine also. A piece of fine wire gauze was then bent and glued over the bottom end of the funnel. The gauze was scavenged from one of those gauze covers for frying pans that are used to stop the fat spattering. Two-part epoxy or silicone sealant would be siliconchip.com.au SECONDARY FUNNEL TEMPLATE (ACTUAL SIZE) MATERIAL: 0.6 –0.8mm ALUMINIUM SHEET RADIUS 50mm fine to glue this in place. To fit the funnel to the top of the pipe, use a PVC pipe end cap. Cut the end out of this cap, effectively leaving only the side wall. Fix the funnel into this “ring” with acrylic or silicone sealant. Since neither of these sealants will stick very well to the PVC, it’s a good idea to run a bead of epoxy around the inside of the ring, after the sealant has cured. Make sure there is no sealant or glue fouling the inside of the PVC ring otherwise it won’t slide onto the pipe later. By mounting the funnel this way, it will slip nicely over the end of the pipe and be held in place by gravity. A hole tapped into the pipe and a machine screw can always be added to make sure it doesn’t move. A small secondary funnel has also been included. This sits between the main collection funnel and the tipping bucket and enables the rain collected from the main funnel to be aimed accurately into the tipping bucket mechanism. RADIUS 3mm It’s best to make the secondary funnel from annealed aluminium sheet since this is much easier to bend into shape. This funnel is held over the tipping bucket by a U-shaped bracket. It would be a good idea to coat the inside surface of the secondary funnel so it is water repellent (as you did for the tipping bucket surface). The tipping bucket itself, along with the secondary funnel, is bolted onto another end cap which slips onto the bottom of the PVC pipe. The two are mounted together to keep them in good alignment. Two M4 x 20mm-long screws (with Just in case you haven’t come across one before, this is a glass-encapsulated magnetic reed switch of the type used in this project. Its contacts are normally open and close in a magnetic field. The most sensitive areas of a reed switch are towards each end. October 2007  71 180 locking nuts) have also been tapped into the end cap and sit underneath each half of the tipping bucket. They are used to adjust the amount the bucket will hold before it tips. Brass or stainless steel machine screws (M4) and nuts should be used throughout for corrosion resistance. There are two larger holes opposite one another near the edge of the end cap. The holes should be about 12-15mm in diameter and are the exit points for the water from the tipping bucket when it empties. Make sure the outside of these holes is also covered with fine wire gauze (glued in place) so that insects or other debris can’t get inside the sensor and foul the mechanism. Calibration Fig.6: here’s how the funnels and the tipping bucket assembly all go together. Note that the magnet is aligned with one end of the reed switch (not with its centre). PRIMARY (MAIN) FUNNEL SILICONE SEALANT “GLUE” 140 100mm PVC PIPE CAP WITH 95mm HOLE Once the sensor is assembled, calibration can then be done. Make sure the end cap is placed on a MOUNTING BRACKET level surface before starting. Calibration is done by slowly dripping water into the primary or secondary POP RIVETS funnel and measuring how much it takes before the bucket tips. Do this 10 or 20 times and average the results. Aim for about 5ml each time, using the adjustment screws under each side of the bucket to fine-tune the tipping point. Ensure the same amount of water is needed no matter which direction the bucket is tipping. To convert the amount needed to cause the bucket to tip into millimetres of rain, first measure the diameter of the top of the primary funnel in centimetres then calculate the area of this opening. (To find the area, divide the diameter by two to get the radius, square this value then multiply by p [ie, 3.1416]). The area in square centimetres will be the number of millilitres of rain the funnel will collect for every 10mm of rainfall. You will get a value of about 250ml for a 180mm-diameter funnel, or about 25ml per mm of rainfall. If it takes 5ml to fill and tip the bucket each time, that is 0.2mm of rainfall for each bucket tip. ALL DIMENSIONS IN MILLIMETRES 150mm LENGTH 100mm PVC PIPE # COVERED WITH MESH TO PREVENT SPIDER/INSECT OR LEAF INGRESS 12 # 50 5 We showed the electronics “box” in Pt.1 last month. However, it needs to be housed so it is protected from the elements (and nosey cows, etc!). A “case” can be made from the same 100mm PVC pipe and a friction-fit pipe end, as were used to make the rain gauge. However, in this instance, I elected to use only a top cover, leaving the bottom open to the elements “just in case” something leaked and it decided to fill with water. 5 POP RIVETS 7 MAGNET 3mm DIAM, 2mm LONG SECONDARY FUNNEL 88 15mm WIDE STRIP OF 0.4mm THICK GALVANISED STEEL SHEET 3–4mm CLEARANCE FROM FACE OF MAGNET TO CENTRE OF REED SWITCH 12–15 END OF REED SWITCH ALIGNED TO CENTRE OF MAGNET DIVIDER Electronics housing 72  Silicon Chip SILICONE SEALANT “GLUE” 100mm PVC PIPE FRICTION CAP TIPPING BUCKET 12.5–15 RADIUS REED SWITCH (GLUED TO BRACKET) AXLE 4mm DIAM HOLES DRAIN HOLE# WASHERS 60 BRACKET FOR TIPPING BUCKET DRAIN HOLE# siliconchip.com.au The box is not secured to the pipe; rather it hangs from simple metal bracket mounted on the top pipe cover. The cabling simply drops out of the bottom of the case. All cabling must be secured to star pickets or to some other mounting poles – a cable dangling in the breeze is too much of a temptation for curious livestock (especially cattle!). Mounting the sensors and the controller Most of the hard work is done. The main job left to do is to assemble and mount the bits and pieces. Since this is designed for use in remote locations, I assumed that a quick and simple way to mount the sensors and weatherproof the electronics was needed. A star picket commonly used for fencing was used. These have convenient pre-drilled holes though which brackets made from bolts and steel strips can be mounted. The photos illustrate how to make these up. The mount for the rain gauge is constructed so that it can be tilted on two axes, enabling the sensor to be levelled when installed. Specifically, the base of the sensor, on which the tipping bucket is mounted, should be set so it is level, otherwise accuracy will be degraded. By the way, I haven’t done a check to see how accurate the rain gauge is but commercial units of this type are typically accurate to within a few percent. As indicated above, the utility box containing the electronics is fitted inside a length of PVC sewer pipe fitted with an end-cap. This end-cap is fitted with a metal bracket bent up from a piece of sheet metal. A second bracket is attached to the utility box, so that it can be hung in place – see photos. Initial set up The only job to do is to perform the clock correction if accuracy better than about five seconds a day is needed. First, start the weather station by inserting three AA batteries into the battery clip. The temperature or rain sensors don’t need to be connected. You will need an accurate means to measure 24 hours to within a second or so. A handheld GPS or good quartz wristwatch will do the job. Alternatively, find a time service on the internet. You will have to use one that gives a seconds reading and automatically increments this (for example, try www.timeanddate.com). First, reset the controller using the Reset button. With the case open, press the clock correction switch (S2) momentarily and note the exact time it was pressed. The LED will come on as soon as the switch is closed and stay on for four seconds to indicate that the clock correction process has successfully started. Note that the clock correction switch will be disabled 30 minutes after a reset (assuming the controller has been programmed with a 30-minute logging frequency). At the same time the next day, about 20 seconds before 24 hours has elapsed, the LED will come on. At exactly 24 hours, press the clock correction switch again. The LED will turn off and the correction value will be stored. This value is stored in the PIC in nonvolatile memory, so is retained even if power is removed from the PIC. If you forget to press the switch, the LED will turn off after about 40 seconds but no correction value will be recorded and the controller will simply resume normal operation. Logging weather data Set up the rain and temperature sensors, power up the weather station, and reset it. Make a note of the time and date at which the reset occurred. The first data will be recorded 30 minutes (or one logging frequency) after the reset. Parts List (Louvred Housing) All sheet metal used in 0.4mm thick galvanised steel (0.6mm thick aluminium is preferable for the louvres themselves but is harder to obtain). Sheet metal 1 170 x 170mm (for top cover) 1 150 x 150mm (for top) 5 400 x 25mm (for louvres) 4 110 x 20mm (for corner supports – you should use galvanised steel for strength to make these even if you do make the louvres from aluminium sheet) Other 30 small pop rivets (to fix louvres to corner supports) 3 M4 x 30mm machine screws & nuts 3 M4 x 20mm tapped spacers 1 mounting bar made from aluminium channel (12 x 12mm), approx 150mm long (for mounting the housing) 2 6-8mm long pop rivets (for mounting bar) 1 50 x 8mm bolt, head cut off, with nut and two washers to suit (for mounting bar) Parts List (Rain Gauge) 1 360mm square sheet metal (main funnel and bucket parts, U-shaped bracket) 1 100mm-diameter semicircle 1 150mm length of 100mm-diameter PVC pipe with friction caps 1 magnetic reed switch 1 3mm-diameter x 2mm rare earth magnet Various screws, pop rivets and scraps of metal siliconchip.com.au October 2007  73 Making The Temperature Sensor Housing For accurate readings, the location of the temperature sensor is important. It must be placed so that it is not affected by radiant heat from the Sun or other direct heat sources. It should also not get wet as evaporation would cool a wet sensor – yet there should be free air movement around the sensor to enable it to equilibrate with the current air-temperature. To achieve the right conditions, professional weather stations usually include a louvred housing that is typically mounted a fixed height above ground level (1.25 metres is apparently the international standard). The housing shades the sensor and stops it getting wet while allowing free air flow. If the housing itself gets hot, it can heat air that passes through it and cause an incorrect reading at the sensor. So the housing should be painted white so as to minimise the absorption of radiated heat. It must also be designed to reduce the chance that the housing itself will create localised heating or cooling of the sensor that’s different to the current air-temperature. A louvred housing can be made relatively easily from thin sheet metal. Aluminium sheet about 0.6mm thick is ideal for ease of handling, low thermal mass and weight but may be hard to obtain. If this isn’t available, use 0.4mm galvanised steel sheeting. The housing design consists of a top, a top cover over this to improve resistance to radiant heat from overhead, four vertical corner supports and five louvres made from bent sheet metal which fix directly to the corner supports. The easiest way to assemble the housing is with pop-rivets. A piece of aluminium channel is also pop- It’s not a template but this photo can be used as a cutting and drilling guide for your temperature sensor housing. And here is that first louvre fixed to the four side supports. Once you have achieved this, the rest is easy! 74  Silicon Chip riveted or bolted on to the top cover for mounting the whole assembly. Commence construction by cutting out all the sheet metal parts (see photo). The dimensions for these parts are given in the parts list on the previous page). Don’t bend any of the parts yet. It’s a good idea to drill the holes that will be needed for assembly now since this is easier to do on flat (unbent) sheet). Start with the top and top cover. First, tape them together in accurate alignment and drill three holes (4mm diameter) as shown on the template – this will ensure that the holes in the top cover align with those in the top when you come to screw the top cover on. Four holes for pop-rivets can also be drilled in the top – see photo below left. Pop-rivet holes can also be drilled in the Here are the components for one side of the housing – the largest piece is the top cover, the four pieces below the side guides. A few minutes later and all louvres are fitted, now ready for the top cover to be fixed in place. siliconchip.com.au louvres. Don’t drill any holes in the corner supports though. Now bend the top and top cover into shape as well as bending the corner supports and louvres as shown in the photo below. Mark lines at 20mm intervals along the corner supports (these will be used to align the louvres). The last line marked will be only 10mm from the end of the corner support and is where the first (bottom-most) louvre will be mounted. Drill and pop-rivet the bottom louvre to the corner supports so its top edge aligns with the 10mm line (see photo). The easiest way to drill the corner supports is to clamp a short length of scrap timber (19 x 42mm cross-section) to the work bench so it protrudes from the bench. Hold the corner support with a large bulldog clip while the louvre is placed over it and the hole is drilled (see photo). The next louvre up can now be popriveted into place, aligning its top edge with the next mark 20mm along the corner support. Fix the remaining louvres into place. When all the louvres are fixed, the top can be pop-riveted on. The top should slide nicely over the upper ends of the corner supports if you have measured, cut and bent accurately. The housing is now almost finished. It’s now time to make the mounting bar, which is made from a piece of aluminium channel. I used 12mm channel since this makes it easier to fit a bolt to the other end (an 8mm diameter bolt will fit easily in the channel). The easiest way to hold the bolt in place is to put it in a vice and crush the top edges of the channel over the bolt shaft (see photo). Two part epoxy will ensure it stays in place. Next, rivet the mounting bar to the top cover after first cutting away a portion of the channel so the mounting bar will sit flat on the top cover (the prototype louvred Drilling holes in small, thin bits of metal is not only tricky, it can be dangerous if you don’t properly clamp and support the work. The mounting bar is made from a piece of U-shaped (channel) aluminium with an 8mm bolt crushed in position then secured with 2-part epoxy. This is then secured to the (inner) top cover with pop rivets. The outer top cover, which helps prevent the housing from heating up and giving false readings, is mounted 12mm above the inner top cover by means of 12mm threaded Nylon standoffs so there is no heat conduction from one part to the other. siliconchip.com.au housing shown in the photos in part 1 had the mounting bar fixed under the top cover but this is clumsy so don’t try it). Now fix the top cover in place with machine screws and spacers. Finally the housing should be painted white to minimise absorption of radiant heat. A can of fast drying spray paint is the easiest way to do this. Remember that several light coats are better than one heavy coat. The temperature sensor itself is mounted on short lengths of wire that are suspended from the corner supports of the louvred housing (simply bend them around the top of the corner supports between the top and the first louvre). The sensor should be mounted in about the centre of the louvred housing and can be held in place with a twist tie or short length of wire. Make sure it can’t drop out when left unattended for a lengthy period. Here we are preparing the first louvre, ready for securing to the corner support with a pop rivet. An upside-down finished view of the housing. The four stiff wires inside the housing support the temperature sensor itself. October 2007  75 Left: the controller box inside its PVC pipe case. It hangs free on brackets fixed as shown above. The pipe mounting bolt is flexible to allow the pipe to be moved at will. The rain and temperature sensors can be plugged in at any time, although, obviously, nothing will be recorded until they are. Even though the temperature sensor is a programmable digital device, the software in the weather station enables it to be plugged in and unplugged even when the weather station is operating. If the rain sensor is left unplugged or is faulty, zero values will be recorded for temperature. There is nothing else to do, except come back in a month – or a year – and download the data. Downloading the data Downloading is also straight forward. Instructions are printed on the front label of the weather station. Freeware data-logging software is used to receive the data (see below) on your computer or laptop. This software will write the data to any file you nominate. Data is transmitted in text form as comma-separated values that can easily be imported into spreadsheets. A “header” is transmitted first, listing the total number of data points recorded since the last reset. The weather station does not record the time directly. You will need to calculate the time of each data record based on the time the weather station was reset (or powered up) and the logging frequency. Don’t forget that the first data set isn’t recorded until one logging period after the weather station is started. Some basic error detection is also built into the software. When each data record is written, the value 255 (decimal) is also written to all four bytes of the next record. During a data dump, if the weather station software encounters these values, it will transmit the following text string “BREAK” then “NULL” on the next line. Since data only up to the last valid record are normally transmitted, such a BREAK will never be seen during a normal dump operation. It will occur if there was a power down and power up, or an internal reboot of the weather station while it was operating. A reboot will occur if the software detects some abnormal conditions during operation, such as a suspicious looking interrupt. It can also occur if the internal record counter becomes corrupted, although this in unlikely. An entire dump of the weather station’s data can also be performed. This will show a BREAK where data finished recording following the most recent reset. BREAKs may also be seen further into the data record from some earlier resets (only those that weren’t overwritten since the last reset). Performing a full data dump of the entire EEPROM contents is easy. Simply do a reset on the weather station just before doing a data dump. A sample spreadsheet is attached showing weather data recorded from 17 January 2007 to 4 March 2007, in my backyard in Canberra. Some plots of the data are also included, including a very heavy rain event where about 50mm fell in 30 minutes. The rain gauge is able to handle both heavy and light rainfall events, although I would expect problems with extremely heavy rain or hail. If you need to change the logging frequency . . . Full-size front panel artwork for the Data Logging Weather Station. It can also be downloaded from www.siliconchip.com.au 76  Silicon Chip The firmware is nominally written for a 30-minute logging frequency, meaning rain and temperature will be recorded every 30 minutes. The logging frequency can be changed by modifying the firmware, recompiling this and reprogramming the resultant hex file into the PIC. The software for the PIC siliconchip.com.au N A T A H G W N I Z A ! M R A OFFE Agilent Technologies Buy yourself one of the world’s most versatile digital multimeters – the incredible Agilent U1252A True RMS – between now and December 31 2007, and you’ll also enjoy a FREE 12-month subscription to SILICON CHIP – Australia’s world-class electronics magazine!* SEE THE REVIEW IN APRIL 2 SILICON CH0I07 P! * offer valid only in Australia. If you are already a subscriber this can be made a gift subscription That’s right: a bonus valued at $89.50, yours free of charge when you buy the Agilent U1252A DMM! It’s so much more than just a DMM – look at these specs: FEATURES: * True RMS measurements * 20 MHz frequency counter * Up to 0.025% basic DCV accuracy * Programmable square wave generator * Frequency, temperature and capacitance measurements * 50,000 counts resolution on both displays * IR to USB connectivity (optional U1173A connectivity cable sold separately) * -20°C to + 55°C operating temperature * Category III 1000V safety compliance * 100 manual data storage points and unlimited data logging points when connected to a PC Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50000 counts Basic DCV accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.025% Displays (50,000 count) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Dual True RMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . AC + DC Capacitance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10nF to 100µF Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 500MΩ Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10A Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.5Hz to 500kHz Math Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Frequency Counter . . . . . . . . . . . . . . . . . . . . . . . . 0.5Hz to 20MHz Programmable square wave generator . . . . . . . . . 0.5Hz to 4800Hz Data logger . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 points (manual) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 points (interval) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Unlimited (PC) Operating temperature . . . . . . . . . . . . . . . . . . . . . -20 C to +55 C Safety compliance . . . . . . . . . . . . . . . . . . . . . . . . . . Cat III 1000V Battery . . . . . . . . . . . . . . . . NiMH Rechargeable with power adapter I/O interface . . . . . . . . . . . . . . . . . . . . . . . . . . IR to USB(optional) Dimensions . . . . . . . . . . . . . . . . . . . . . . . . 203.5 x 94.4 x 59.0mm Approximate weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 527g Here’s how to take advantage of this amazing offer! WA, NT, SA: ACT, NSW, QLD, TAS & VIC: CALL! FAX:# BY PHONE:* TRIOBY(02)SMARTCAL PTY LTD OR MEASUREMENT INNOVATION PTY LTD 9939 2648 (02) 9939 3295 FAX! 24 Hours 7 Days 9-4 Mon-Fri PHONE: 1300 853 407 FAX: 1300 853 409 EMAIL! <at> sales<at>triosmartcal.com.au siliconchip.com.au www.triosmartcal.com.au ONLINE! PHONE: 08 9437 2550 FAX: 08 9437 2551 info<at>measurement.net.au O 2007  77 www.measurement.net.au ctober An Excel spreadsheet from the author’s installation outside Canberra. Because the data from the Weather Station is virtually “universal” in format, it can be used in a wide range of applications. contains the following defined constants near the start: LOG_FREQ EQU D’6’ ; Frequency (minutes) with which data is logged HRS24 EQU D’240’ ; = (No of minutes in 24 hours)/LOG_FREQ Changing these will change the logging frequency. The above example shows a logging frequency of 6 minutes. Setting LOG_FREQ to 30 (decimal) and HRS24 to 48 (decimal) will give a 30 minute logging frequency and a normal 24-hour clock. Logging frequencies down to one minute are possible but the HRS24 value can only be a maximum of 255. The only thing HRS24 affects is the frequency with which clock error correction occurs (including the initial setting of the clock error). So if LOG_FREQ is set to 1 and HRS24 set to 255, the PIC will apply the clock correction value every LOG_FREQ x HRS24 minutes (ie, 1 x 255 minutes). Similarly, performing an initial 78  Silicon Chip clock calibration will complete 255 minutes after it is started, not 24 hours later. Obtaining parts & software The data logging software is available from www.eltima.com/products. Download the freeware “RS232 data logger”. The 3 x 2mm rare earth magnet is available from Oatley Electronics in Sydney (www.oatleyelectronics. com) for 25 cents each plus $7 pack and post). Similar 3 x 1mm magnets are also available from www.frenergy.com.au (12 cents each; $5.50 pack and post) – you will need two of these stacked to get a magnet with the same power as a 3 x 2mm magnet. I contacted both of these suppliers and neither can offer any further discount on shipping. This is one case where it costs far more to pack and post than the (tiny) items are worth. If you wish to avoid the high pack and post charges, I’m willing to provide them for a nominal shipping charge. Check my web page for details (www. evans-pure.net/weather.htm). Alternatively, you may be able to scrounge a suitable magnet or two from, say, an old hard disk drive. Most reed switches are quite sensitive and will work with most magnets. The advantage of the “rare earth” magnets used here is their incredible size-topower ratio. Commercial rain sensor For those who don’t want to make their own rain sensor, a commercially available sensor is available for about $200 that uses a similar mechanism to the sensor described here. It is made by Peet Bros in the US and is sold in Australia by Sphere Innovative Technologies (www.sphere.net. au/site/products.php?cat=wm_acc). You will need to order the “Rain gauge – wired”. I haven’t tested it myself but have investigated its specifications and am confident it will work. SC siliconchip.com.au PRODUCT SHOWCASE New V2 UltraWAP multi-mode WiFi Access Point Freenet Antennas has released Version 2 of the highly successful UltraWAP multi-mode WiFi access point (AP). The UltraWAP is like a swiss-army knife of WiFi units. It has five modes allowing it to behave as: (1) an AP – the centre of a Wireless network, (2) a Station (client if you like) where it connects to an AP, (3) Bridge – acting like a LAN switch in the sky, (4) Wireless Distribution System (WDS) – acting simultaneously in AP and Bridge modes, or finally (5) Universal Repeater – acting simultaneously in AP and Station modes. The Version 2 (V2) UltraWAP sees a new radio chip introduced with much improved receive performance. Freenet Antennas has measured a clear 5dB improvement in receive performance compared to the V1 unit. That translates to a 78% increase in receive range! Tenrod’s Digital Video Recorder Module Do you need to record movements or events and not have to wait for them to happen? In video or in still images? Perhaps store them for later retrieval and playback? Tenrod have introduced an easy-tooperate, automatic and low-cost video recorder (in module form) – which will do all of this and more. With its motion detect feature, the DVR81XX module can record movements or events (in video or still images) of the target area and store them on an SD card. A 1GB SD Card can store up to 15,000 seconds of video or 17,000 still images. When there is no activity, there is no recording, saving storage space. At the same time, the module can provide a live output to a TV monitor siliconchip.com.au from 2 input channels of cameras. It has picture-in-picture feature as well as on-screen-display. It also has an alarm output which can alert an operator, trigger an alarm or activate other functions. The module is without enclosure, to provide versatility for installing into tight spaces or into enclosures of the user’s choice. It requires only a single DC (9V to 12V) power source to operate the whole system. The recorder would be ideal for continuous monitoring of a place or Contact: Tenrod Australia Pty Ltd 1/24 Vore St, Silverwater NSW 2128 Tel: (02) 9748 0655 Fax: (02) 9748 0258 Website: www.tenrod.com.au It also means more distant signals can be detected and connected to. Because of the extra receive sensitivity, a pair of these units can make a 20km point-to-point link when coupled with 19dBi grid antennas and antenna coax – without violating the ACMA 36dBm radiated power limits. (Refer to last month’s SILICON CHIP). The UltraWAP comes in a range of transmit power options, from 60mW to 200mW making it the most versatile WiFi unit on the market today in Australia. At prices starting from $99, it is also the best value. Contact: Freenet Antennas 3 Barker Place, Bicton, WA 6157 Tel: (08) 6262 3333 Fax: (08) 9319 3275 Website: www.freenet-antennas.com processes that need to be analysed for research or for development or troubleshooting. The memory storage and playback facility will facilitate the data retrieval for this analysis. It can be used with infrared cameras for night-time operation. Kits complete with cameras and cables are available to make a convenient start to putting up a system. Small 4-inch TFT colour LCD screens are also available for use as a small portable monitor in conjunction with the module. TOROIDAL POWER TRANSFORMERS Manufactured in Australia Comprehensive data available Harbuch Electronics Pty Ltd 9/40 Leighton Pl. HORNSBY 2077 Ph (02) 9476-5854 Fax (02) 9476-3231 October 2007  79 Clock Radio with Docking Station Most people are creatures of habit, leaving their clock radios (and other radios!) on one station. Maybe it’s because most clock radios are so fidgety to change. But sometimes the programs on your favourite station are not what you want to listen to. Wouldn’t it be nice to have an alternative without lots of fiddling? Jaycar Electronics have a neat solution to this problem with this very advanced Clock Radio. Actually, they describe it as a Docking Station with AM/FM Digital Alarm Clock. That’s because it is not only an advanced AM/FM radio with a host of alarm functions – and 10 AM /20 FM preset stations – it will also play back music from a USB “stick” and/or an SD/MMC card. You can even use it to transfer files between USB and SD/MMC. What’s more, you can tailor the sound response to the way you like it, just like the newer hifi systems. Settings are flat, pop, classic, rock, jazz and X-bass. Like most clock radios, it has a snooze function. It also has dual alarms (which you can set to wake up to your choice of source – buzzer, radio, USB or SD/MMC) but unlike most clock radios, it has a weekend function which turns the alarm off on Saturday and Sunday. Settings are backed up with two AA cells (it’s normally mains powered). The output power is more than adequate – 1.5W x 2 and it has a headphone output as well as RCA outputs. I have to confess that setting up took a bit longer (!) than the average clock radio but once done, it was a joy to use. With a recommended retail price of $99.00, it’s certainly not as cheap as the average clock radio these days but it does a whole lot more and is worth every cent. It’s available from all Jaycar Electronics stores* and resellers (Cat GE-4064). * Jaycar have re- Contact: cently announced Jaycar Electronics (all stores) the relocation of 100 Silverwater Rd, Silverwater NSW 2128 two of its Syd- Ph: (02) 9741 8555 Fax: (02) 9741 8500 ney area stores to Website: www.jaycar.com.au larger premises – Bondi Junction store is now at cnr Birrell and Bronte Roads (ph 9369 3899) and Campbelltown store is now at 1/50 Queen Street (4620 7155). 80  Silicon Chip New Test & Print Kit now available Testing and tagging of portable electrical appliances can be very labour intensive. Wavecom Instruments have released two new testers which make the testing and tagging and the record keeping associated with it much easier. The first has a memory built into it. It can store 5000 test items. Download the tests to be done today – or this week – to the memory in the tester, do the tests and upload the results back to the main database at your leisure. The kit includes a printer so tags are printed on site after the completion of the test. Multiple tests per item can be stored for consecutive tests. The second new tester will be ideal if you don’t need the memory function but just want to test & print. The system comes complete in a plug-in-and-start-testing case. Labels printed from tester can be customised to user needs. User names, site names and retest frequency are changed on the fly and printed on the robust label within two seconds. All tests, including load, leakage and RCD tests, have results logged and recorded for uploading to the WinPATS MX software. WinPATS MX provides the user with a Contact: comprehensive asset Wavecom Instruments management tool 257A Grange Road, Findon, SA 5023 for a large variety of Ph: (08) 8243 3500 Fax: (08) 8243 3501 OH&S issues. Website: www.wavecom.com.au 25 x 25mm 15W DC/DC Converter The revolutionary RECOM RP15-xxxxSA and RP15-xxxxSAW series DC/DC converters are just 25 x 25mm and have a height of only 10mm, deliverering a power density of 38W/ in³ (2.3W/cm³). That’s half the size of the industry standard. An efficiency of up to 87% allows these new galvanically isolated converters to have an operating temperature range of -40°C to +68°C at full load without the need for any external cooling fans. However, the full load upper temperature limit can be extended further to 73°C with the optional heatsinking pack. By means of simple external filter, EN-55022 Class B limits can be met (an appropriate common mode choke is also available from RECOM), otherwise no external components are required for normal operation. A trim pin allows the outputs to be adjusted by 10% and Contact: a remote pin can Cutter Electronics be used to power- 5 Highgate Way, Rowville, Vic 3178 down or sequence Ph: (03) 9753 9911 Fax: (03) 9753 9455 the output. Website: www.cutter.com.au siliconchip.com.au Trio Smartcal’s new under-$1000 “Atten” Colour Scopes! Like to Phidget ? Phidgets are an easy to use set of building blocks for low cost sensing and control from your PC. Using the Universal Serial Bus (USB) as the basis for all Phidgets, the complexity is managed behind an easy to use and robust Application Programming Interface ( API ). Applications can be developed quickly in Visual Basic, VBA ( Microsoft Access and Excel), Labview, Java, Delphi , C and C++. For Hardware Developers Easy Access to USB as an Interface. Clear separation of hardware and software. No need to explain bit, bytes, and baud to the programmers : instead refer them to Phigits APIs. For Programers Wrap Phidget Libraries with your own Propriety software. No reverse engineering - protocols available. There are a number of open source projects to get involved in. Reach out into the world and make things happen. Aimed at the enthusiast and economy-conscious buyers, the ADS7000 series range of low-cost Digital Oscilloscopes from ATTEN, while low in price, are value-packed with features such as sample rates of up to 1GS/s per channel and the inclusion of USB on all models. PC communications software is also included in the price as is the USB cable to link to your PC. Features include peak detect for glitch capture, average mode for noise reduction, pulse width trigger, video trigger with individual line select and a full suite of automatic waveform measurements. Equivalent time sampling increases the resolution on faster repetitive signals too. Measurement cursors are also standard as is an intelligent AUTOSET function that enables the user to select positive or negative edges, an individual waveform cycle and series of cycles. Window mode is more than just a basic magnification or zoom function as found on many other low cost oscilloscopes. On the ADS7000 series when the window mode is selected it actually adjusts the timebase, increases the sample rate and adjusts the trigger delay to bring the selected area on screen with the optimal capture settings. This ensures that the waveform feature of interest is displayed at the highest possible resolution. Backed by a 3-year warranty and in-country support, these new scopes will be a welcome addition to many enthusiasts’ test benches – and with Christmas only four months away, will make the ideal present, even for yourself. Prices start at $895 (+GST) (or $984.50!) for a 25MHz, 250MS/s, 2-channel model. At the other end of the scale, the flagship 200MHz model has 1GS/s per channel, USB device port (for PC connect) and USB host for memory stick, and costs just $1,995 +GST. Monochrome models are also available from just $795 +GST. For Researchers New Physical interfaces can be easy as software widgets. Research and study, not solder and debug hardware. Cheap, available hardware makes it a snap to reproduce results. Phidgets are easy to program and use. No knowledge of hardware, microprocessors, USB, communication protocols, is needed. An imagination is recommended however. Your Australian Distributor OzzieSim Flight Simulator & Hobby Technologies Email: sales<at>ozziesim.com.au www.ozziesim.com.au Wireless Data Networks Long Range Antennas 900 MHz 2.4 GHz 3.5 GHz 5.8 GHz Omidirectional Sector + Mobile Hills distributes smartBridges outside wireless network point to point & multipoint products. airPoint - 2.4GHz Nexus - 5.8GHz Contact: Trio Smartcal 3 Byfield St, North Ryde NSW 2113 Ph: (02) 9889 3534 Fax: 1300 853 409 Website: www.triosmartcal.com.au siliconchip.com.au Discover more: Phone: +61 2 9717 5275 Email: rolf.roelfsema<at>hills.com.au www.wireless.hillsantenna.com.au October 2007  81 LOOP ANTENNA AND AMPLIFIER for long-distance AM radio reception Design by Branko Justic* Words by Ross Tester • Listen in to AM radio stations you only dreamed existed! • Separate close stations • Suits upper AM broadcast band • Small enough for flats & home units 82  Silicon Chip siliconchip.com.au * Oatley Electronics O NCE UPON a time, listening to long-distance radio signals (whether on the broadcast or shortwave bands or even the amateur bands) was a popular hobby. Hours upon hours were spent, listening for that elusive station . . . the ability to bring very weak stations “out of the mud” was the ultimate thrill. In the 21st century (and at the risk of earning the ire of diehard shortwave listeners!) those days have all but gone. Today, there is little interest in the big, high-performance communications receivers of last century. A lot of gear came out of WWII, perhaps modified but there was an enormous amount of commercial receiver equipment on the market as well, reflecting the popularity of “listening”. Who can forget (if you were around 50 years ago!) the Marconis, Hallicrafters or Gelosos, the Nationals, Eddystones, Collinses or the build-ityourself Heathkits? Speaking of build-it-yourself, the late Ian Pogson described two mighty “Deltahet” Wadley-Loop communications receivers in “Electronics Australia” magazine during the 1960s and 1970s. Later on came the Frogs (Yaesu’s famous FRG-7) and many more. Have I missed your favourite? Sorry! Those who still indulge in the art of “listening” are these days just as likely to use WinRadio in/on their PCs – which in many ways outperforms even the best of the communications receivers of yore. In fact, the vast majority of receivers today have little more than the AM and FM broadcast bands. The aerial There are three things which make a receiver “good”. Two are fixed (at the whim of the designer or manufacturer). First is the receiver’s sensitivity, which is its ability to resolve very weak stations. Second is the receiver’s selectivity, which is its ability to separate stations whose transmit frequencies are very close. Note that NO receiver, on its own, can separate stations which are on the same frequency. However, the third factor, which can often help a receiver distinguish between stations on adjacent frequencies (and even sometimes the same frequency) is the aerial or antenna. Even though the terms are virtually siliconchip.com.au Here’s the top PC board mounted inside one of the low-cost Oatley weatherproof cases. The two cables entering at left are for the loop antenna above (you can just see the loops behind the case lid). All four wires in this cable are soldered to the underside of the board together. The cable entering in the middle is the downlink – this cable has all four wires individually soldered to the underside of the PC board . interchangeable these days, no selfrespecting old-timer would ever call his aerial an antenna. Antennas were those small flimsy things designed to pick up TV! Unless you have made an in-depth study of aerial/antenna theory, to most people (many electronics hobbyists included) it’s a black art. Sure, everyone knows aerials/an­ tennas are the “inductor” part of a tuned circuit which, depending on the antenna length, resonates at a particular frequency, according to the formula 1 2π√LC where L is the inductance in Henries and C is the capacitance in Farads. Wanted frequencies (ie, the station you want to listen to) can pass virtually unhindered but (at least theoretically) all other frequencies are rejected. If you make the frequency of the tuned circuit variable, then you have October 2007  83 LOOP ANTENNA DOWNLINK AMPLIFIER (IC1a) VARIABLE “CAPACITOR” (VARICAP DIODES D1,D2) 530 Modern receivers are often quite reasonable in the selectivity and sensitivity department, so all that’s left for us to play with is the antenna. Even if the receiver has provision for an external antenna and earth, you might be quite disappointed with the performance. That’s because a random-length antenna is unlikely to be impedance-matched to the receiver and unlikely to be resonating anywhere near the required frequencies. 1600 LOOP AROUND AM RADIO 0-10V OR 0-8V VARIABLE SUPPLY (VR1) PLUGPACK SUPPLY AND REGULATOR (REG1) The loop antenna A far better approach is to use the one we’ve gone for here – a loop antenna with an in-built amplifier. Moreover, a loop antenna exhibits reasonably good directivity – if you’re trying to pick up a distant station and another station is swamping it, you can rotate the loop to “null out” the unwanted one. Coupling the loop antenna to the receiver is made simple because no physical connection is required. A second, single-turn loop couples the signal into the radio’s in-built ferrite rod antenna. The distance between the loop antenna and the receiver can usually be as much as you require – up to several tens of metres, in fact. We should point out now that this Fig.1: block diagram of the Active Loop Antenna. The first two blocks are connected in parallel to form a tuned circuit. a means of tuning over a specific band of frequencies. Well, at least that’s the way it’s supposed to work. Old timers will tell you they used to use another aerial formula: “as long and as high as possible”. You’d see many a length of wire stretched on poles “down the backyard” – or further. But not everyone these days has the room (or the neighbours!) to allow this to happen. You need something smaller! for those who want to listen to distant, weak or interference-prone AM radio stations, particularly those in the upper portion of the band. This tends to be where the weaker stations are located – most country commercial AM stations are about 2kW; some are even less. Compare that with city commercial stations and the ABC which can be up to about 50kW! We mentioned before that the aerial/ antenna (OK, let’s standardise on the word “antenna”) can make a great deal of difference to the performance of a receiver. Back to the future This project is specifically intended D D C C REG1 78L08, 78L10 OUT +11-30V IN GND 6 15nF 5 7 47k 220k ANTENNA LOOP IC1b 470k 15nF 15nF 220k 2 3 K K A A 4 15nF D1,D2 KDV149 1 IC1a 56 15nF B B A A SC 100 F OUTPUT LOOP (AROUND RADIO) 56 IC1: BA4560 47k GND LOWER BOARD UPPER BOARD KDV149 2007 100 F 47k TUNING 8 DOWNLINK CABLE 100 F VR1 ACTIVE AM LOOP ANTENNA K 78L10 BA4560 4 8 A COM 1 IN OUT Fig. 2: the antenna loop picks up radio signals which are amplified and sent to an output loop, which re-radiates it into an AM radio receiver. 84  Silicon Chip siliconchip.com.au A * * B * 47k 470k 47k C IC1 BA4560 A A © oatleyelectronics.com * 15nF 15nF 220k 15nF 15nF 220k K 100 F 56 D * + K D1 D2 * 15nF K256B UPPER BOARD ENDS OF ANTENNA LOOP CABLE TIES DOWNLINK CABLE Fig.3: component overlays for the top and bottom PC boards, with their same-size photos alongside. Note that the proto­ type top (amplifier) board shown here used a single SR1060 Schottky diode in the tuning circuit whereas the final version uses two KDV149 varicap diodes in parallel. + 56 100 F REG1 * START OF COUPLING LOOP AROUND RADIO 100 F V+ * * * – 11–30V DC GND * D + *B + *A C * FINISH OF COUPLING LOOP AROUND RADIO © oatleyelectronics.com * ALL SOLDERED TO COPPER SIDE OF PC BOARD VR1 47k K256A LOWER BOARD project will NOT work on any AM radio which does not have an in-built ferrite rod antenna – this is the only way the received signal is coupled to the radio. Incidentally, if you have a radio without a ferrite rod antenna but with antenna and earth connections, a somewhat similar loop antenna, designed to plug in to such connectors, was described in the March 2005 issue of SILICON CHIP. How it works Take a look now at the block diagram (Fig.1). It shows the operation of the loop antenna. Countless electromagnetic waves passing through the wire loops – generated by anything from lightning to electric motors to radio and television stations – induce tiny electric currents at those frequencies. The tuned circuit, consisting of Xframe-mounted coil loops in parallel with a variable capacitance (we’ll explain how this is achieved in a moment), effectively filters out almost all of these currents, except for the ones which correspond to its resonant frequency. The resulting narrow band of signals is then fed into an amplifier, based on op amp IC1a. siliconchip.com.au The amplified signals are then fed to another coil, this one designed to wrap around the AM receiver. This loop re-radiates the signal so that the ferrite rod aerial coil inside the radio can receive it again and process the signal just as it would any other radio signal it receives. What we are doing, therefore, is essentially “preconditioning” the signal so that the radio itself doesn’t have to try hard to extract the wanted signal. Remember those three things we mentioned earlier which determine a receiver’s performance? Well, this circuit not only boosts the signal level, making the receiver more sensitive to weak signals, but also adds another stage of filtering, making the receiver more selective. As a result, the performance must be better – and in fact can be markedly better! To keep interference to a minimum, the X-frame loop antenna itself should be mounted outside the home, well away from motors, switches, etc. Making the tuned circuit variable As you probably know, you can make a tuned circuit’s basic frequency variable by varying either the inductance or capacitance (remember that formula above?). In general, it’s a lot easier to adjust the capacitance, although many multi-band radio receivers do change coils (inductance) when switching bands. We could use a small variable tuning capacitor but these are not only hard to get, they’re also getting rather expensive. The miniature ones commonly Modifications & An Alternative Antenna Configuration The original circuit developed by Oatley Electronics used a single SR1060 Schottky diode as the variable capacitance diode and this covered just the 900-1600kHz end of the broadcast band. This device is shown in the photos but was subsequently replaced by two KDV149 varicap diodes, enabling the entire broadcast band to be covered. Note that if you don’t want to build a large wooden antenna mast, you can achieve similar results by winding 10 turns of wire (spaced about 10mm apart) on a plastic hobby storage box (or crate) measuring about 350 x 350 x 260mm deep October 2007  85 10 5 x 4mm DIAMETER HOLES SPACED 10mm APART HORIZONTAL ARM 35 35 720 WATERPROOF ENCLOSURE FOR TOP PC BOARD MATERIAL: 70 x 20mm DRESSED PINE OR SIMILAR 20 70 70 VERTICAL ARM/POST 5 x 4mm DIAMETER HOLES SPACED 10mm APART ALL DIMENSIONS IN MILLIMETRES 10 Fig.4: here’s how to cut out your timber to make the frame and “mast” for the Active Loop Antenna. The two pieces of timber form a cross with the loops of wire forming a square (turned 45°) through holes drilled close to its three outer ends and an equivalent distance down the “post”. A knot in each end of the loop will keep it nice and taut – just be careful you don’t pull the cross out of square as you pull the loops through. The top PC board mounts on the post at a convenient position under the coil loops with the downlink wires secured to the post using cable ties. Don’t use a length of wire as this could constitute a shorted turn around the wires and effectively kill some or all of the signal. sold these days are incredibly fiddly to use and not at all conducive to tracking down weak radio signals! But there is another way to obtain a variable “capacitor”. Many semiconductors exhibit a change in capacitance when the voltage across them is changed. Varicap diodes are one such device and in this circuit, we have used two such diodes in parallel to achieve 86  Silicon Chip 8V or 10V DC by REG1, depending on the regulator used (either a 78L08 or a 78L10). The resulting rail supplies the amplifier IC directly and is also fed to a 47kΩ potentiometer (VR1). VR1’s wiper is in turn connected to the cathodes of the paralleled varicap diodes (D1 & D2) via a 220kΩ resistor. At the top of its travel, the wiper will have the full 8V or 10V connected to the varicap diodes, while at the bottom, it will of course be near enough to 0V. The antenna coil is coupled into the varicap diodes diode via a 15nF capacitor. This prevents the DC voltage which is applied to the varicap diodes from being shorted to ground via the quite low resistance of the antenna coil. Similarly, the output from the tuned circuit is coupled to the input of op amp IC1a via another 15nF capacitor so it cannot introduce DC into the amplifier circuit. Finally, we should point out that only one of the two op amps in the BA4560 package is used. The other has one its inputs connected to the positive supply and its other input to its output to ensure that it doesn’t become unstable. Construction ENCLOSURE FOR TOP BOARD MOUNTS HERE AS LONG AS IS NEEDED the required tuning range (ie, right across the AM broadcast band). Power supply The supply voltage for this project can be quite wide – from about 11-30V DC. A nominal 12V plugpack, for example, will usually give about 16-18V unloaded and would be fine. This voltage is regulated to either There are three parts to the project – two PC boards plus the “X”-shaped timber antenna support which houses the turns of telephone cable forming the antenna. On one board, we have the amplifier section and the terminations for the loop antenna. The second board carries the power supply plus the connections for the loop to place around the AM radio receiver. Between the two boards is the downlink wiring. Start by making your timber “X” frame, using Fig.4 as a guide. You can use just about any scrap timber that you can find (but we wouldn’t use Pyneboard or other composites if the antenna is to be erected out in the weather). Any timber used should have generous coatings of paint applied to weatherproof it. Don’t forget to drill all the holes for the wire before you glue and screw the sections together – it’s a lot easier to drill flat timber! Wind the five turns for the coil through the holes, starting with an outside hole closest to where the top PC board will be mounted – leave siliconchip.com.au Parts List – Active Loop Antenn a yourself about 200mm or 1 PC board, 31 x 94mm , code OE-K256A so of cable to work with 1 PC board, 58 x 48mm , code OE-K256B past the position where 1 Weatherproof plastic box (eg Oatley HB4) the PC board goes. Tie a 1 30 x 54 x 83mm pla stic box single-loop knot in the 1 8-pin IC socket cable as it passes through the first hole Semiconductors Continue to pass the 1 BA4560 dual op am p (IC1) wire through the other 1 78L08 or 78L10 volta ge regulator (REG1) three outside holes, then 2 KDV149 varicap dio des (D1,D2) the next across and so Capacitors on until the coil is com3 100μF 16V electroly tic plete. As you go, keep 5 15nF disc ceramic (code 15n or 153 or .01 the turns of the coil nice 5μF) and taut but not so taut Resistors (0.25W 5%) as to pull the timber out 1 470kΩ (code yellow purple ye llow gold) of the “X” shape. 2 220kΩ (code red red yellow go ld) 2 47kΩ When completed, (code yellow purple ora nge gold) 2 56Ω tie a single-loop knot (code green blue black gold) 1 47kΩ linear potentio in the last hole so that meter (and knob to su it). it keeps the wire loops Miscellaneous (not includ ed in Oatley Electronics taut. Again, leave yourkit) Timber, screws and mo unting hardware as req self 200mm or so of cauired 40m of 4-wire telepho ne cable or equivalent ble underneath where the PC board will mount and then cut the remainder off. Hang onto that – you’ll need it shortly for the downlink! wire and so offers some protection from, for example, birds sitting on it PC board construction or even pecking at it! It doesn’t matter which board you If you use telephone cable for the start with – both are quite simple and loop antenna wiring, simply connect should only take half an hour or so to all four wires in parallel as you solder complete. them to the PC board. The same applies On the loop antenna board, the for the output loop – the one which only polarised components are the goes around your radio. The wires amplifier IC, the electrolytic capacitor can be twisted together to make this alongside it and the varicap diodes. easier. Note that all connecting wires Start by installing the smallest solder to the pads on the underside of components, ie, the resistors and the PC board. non-polarised capacitors, then install You might be wondering why each the semiconductors and the electrosingle wire of the telephone cable lytic capacitor. Don’t worry about was not connected in series with its the loop or downlink wiring at the mate and terminated as such on the moment. PC board. Wouldn’t this create a sigOn the power supply board, three nificantly greater inductance (ie, four of the five components are polarised times greater)? so make sure you get them in the right Oatley Electronics originally had way. The potentiometer will only go exactly the same idea. Unfortunately, in one way (otherwise the shaft points when they tried it out, they found that inwards!). the capacitance of the closely-spaced wires within the cable started to create Loop and downlink wiring its own problems. In the prototype, 4-wire telephone They found that by paralleling all cable was used because this hapfour wires in the cable, this problem pened to be on hand – even though was eliminated. More importantly, the loop antenna does not use the they found that the overall perforfour individual wires (however, the mance of the antenna was better! downlink does). In the downlink, all four wires in Therefore you could just as easily the telephone cable are used indepenuse single-conductor wire for the loop dently and are connected to the points if you wished. Note that telephone A, B, C & D on the PC boards. cable is quite a lot tougher than single With coloured wiring in the cable siliconchip.com.au (black, red, blue and white), it’s not easy to get it wrong! This downlink wiring can be quite long – the prototype had 20m between the two PC boards and there didn’t appear to be any loss of signal compared to a 5m separation. If you need more distance, give it a go – you have nothing (except signal!) to lose. In use If possible, make a complete turn around the radio receiver with the output loop (remember, the radio must have a ferrite rod for this antenna to work). How do you know if it has a ferrite rod antenna? If you can turn it on and it works without anything connected, it’s a pretty fair bet that it has one! Virtually all small AM radios have a ferrite rod antenna inside. Tune the radio to the weak station you want to listen to. Now adjust the potentiometer slowly – at one point, you should find a significant increase in the level of that station (or a decrease in any other stations that are interfering with it). Also recall what we said before about the antenna being able to turn so that it faces the wanted station – by facing, we mean broadside on, or if you take a line across the X frame the wanted station should be perpendicular to that line. The antenna will work equally well from both sides. However, if you turn the antenna through 90°, you should find that its performances decreases significantly. Conversely, any other stations that are now broadside-on SC will be much better. WHERE FROM, HOW MUCH? This project was designed by Oatley Electronics who retain the copyright. A kit for this project (K256), which includes both PC boards, on-board components and cases (as listed above) is available from Oatley Electronics, for $AU22.50 The kit does not include the 4-wire telephone cable nor any timber or mounting hardware. Contact Oatley Electronics via their website: www.oatleyelectronics.com or call (02) 9584 3563. October 2007  87 SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au/ SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au/ SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au/ SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au/ 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. Bi-directional variable speed drive includes regeneration Designed for use in a self-balancing scooter, this variable speed pulse-width modulated (PWM) drive is bi-directional and includes regenerative braking to improve overall efficiency. With PWM drives, the key to efficient regeneration is to make sure the pulse repetition period is at least an order of magnitude shorter than the effective time constant of the DC motor armature winding. For most motors, this means a pulse repetition frequency of 2kHz or more, although to be inaudible, above 20kHz is preferable. Many “analog” drives use a sawtooth wave generator and a comparator circuit to generate the required PWM signal but often the pulse fre- FWD REV PWM Q1 Q2 Q3 Q4 0 0 0 Off Off Off Off 0 0 1 Off Off Off Off 0 1 0 Off On Off On 0 1 1 Off On On Off 1 0 0 Off On Off On 1 0 1 On Off Off On 1* 1* 0* Off On Off On 1* 1* 1* On Off On Off * Not permitted by the PICAXE software but not fatal for Q1-Q4 if it occurs BITS 7 BYTE 6 5 4 3 2 1 0 0 VSD Address (0-7) 0 Speed Command Data (bits 7:4) 2 VSD Address (0-7) 1 Speed Command Data (bits 3:0) quency is limitNeville Ar ed to only a few is this mmstrong onth’s 100Hz. This winne design uses the Peak At r of a las internal PWM Instrum Test ent hardware module in a PICAXE-08M micro and the pwmout software command. This ‘digital’ approach resulted in a stable drive capable of up to 32kHz. Software running in the PICAXE generates additional FWD and REV signals, which are then logically combined with the PWM signal to produce the appropriate gate signals (G1-G4) for four power Mosfets Q1-Q4 arranged in a conventional H-bridge. It is very important with H-bridge configurations to ensure that both devices on one side of the bridge are NEVER switched on simultaneously, otherwise they will be destroyed. This is achieved by having “dead time” and is provided by flipflops comprising IC2c&d and IC5c&d. The RC circuits at pins 10 & 12 of the Schmitt trigger NAND gates ensure that, for example, the gate drive pulse for Q1 is removed 100ns before the drive pulse is applied to the gate of Q2, and vice versa. By using both P-channel & Nchannel power Mosfets, the need Contribute And Choose Your Prize As you can see, we pay good money for each of the “Circuit Notebook” items published in SILICON CHIP. But now there are four more reasons to send in your circuit idea. Each month, the best contribution published will entitle the author to choose the prize: an LCR40 LCR meter, a DCA55 Semiconductor Component Analyser, an ESR60 Equivalent Series Resistance Analyser or an SCR100 Thyristor & Triac Analyser, with the compliments 92  Silicon Chip of Peak Electronic Design Ltd www. peakelec.co.uk So now you have even more reasons to send that brilliant circuit in. Send it to SILICON CHIP and you could be a winner. You can either email your idea to silicon<at>siliconchip.com.au or post it to PO Box 139, Collaroy, NSW 2097. siliconchip.com.au for the usual supplementary power supply to drive the gates of the highside Mosfets is avoided. The TLP251 photocoupler devices not only provide the necessary lowimpedance drive for the Mosfet gates very simply, they also provide optical isolation from the potentially noisy 24V, high-current circuitry. In the software, an 8-bit speed command is sent to the PICAXE as two bytes of data via a serial input at pin P4. Each byte contains four bits of address data and four bits of the speed command data. This approach allows up to eight drives to be controlled from one RS232 serial port. The baud rate is 2400bps (8N1 frame). The 8-bit speed command expected by the PICAXE software is a ‘2s-complement’ binary number in the range +127 to -128. Full forward speed corresponds to +127 and full reverse speed corresponds to -127, with stationary corresponding to zero. A speed command of -128 disables the drive by clearing both the FWD & REV signals, which results in all four Mosfets being switched off. This feature could be useful on those occasions when it is preferred that the motor coast to a stop rather than coming to a “controlled” stop with regenerative braking. This circuit is very energy efficient. Apart from being regenerative, the switchmode operation ensures that power dissipation in the Mosfets is very low. When driving a 250W (12A) motor, and with minimal heatsinks, the Mosfets remain cool to the touch. Since each Mosfet is rated at above 40A, the drive should be capable of controlling motors up to 1kW with appropriately sized heatsinks and wiring. Note that a suitable fuse or other short-circuit protection will be needed for the 24V supply line. The TLP251 devices are available from RS Components (Cat. 2610104), and the IRF4905 & IFRZ44 Mosfets are available from Oatley Electronics for about $6 a pair. The PICAXE-08M can be obtained from MicroZed for under $6, giving a total cost for all the semiconductors of around $50. The software will be available on our website for download. Neville Armstrong, Templestowe, Vic. siliconchip.com.au October 2007  93 Circuit Notebook – Continued Pea & thimble or 3-card trick This circuit is an electronic version of the old con game designed to separate the naive from their money. The operator (the Shark) moved the pea under one of three thimbles which were slid about on a table. The other player (Mug) put his money on the thimble hiding the pea. The game was made easy at first to allow the Mug to win a few times and allow his confidence to grow but he finally lost all his money. The shark has a set of three LEDs and three pushbuttons. Pushing any button makes the associated LED light up. Pushing another button extinguishes the first LED and lights another. Hence, pushing the Shark’s buttons “moves” the lit LED. The two dark LEDs represent the empty thimbles. The Shark first shows how this works and you can arrange his buttons in the same order as the LEDs or to confuse matters, you can jumble the order. The Mug has to follow the pattern as demonstrated, easy or confusing. When the LEDs are later covered with three thimbles or opaque bottle tops, and the Shark is operating, the Mug can try to follow which LED is alight at any time. The Mug also has three pushbuttons and three LEDs. When the Shark has finished shuffling, the Mug presses a button to light his LED opposite the one he thinks is lit. When the Shark’s LEDs are uncovered, the Mug finds out whether he has won or lost. On the Mug’s side is a normally-closed (NC) pushbutton switch to clear his LEDs. Each player’s LEDs are lit by a pulse applied to the gate of an SCR which stays on after the respective pushbutton is released. The capacitors between the SCR anodes on the Shark’s side enable them to be turned off while the shuffling is occurring. This method of turning off SCRs is called “forced commutation”. IC1, the 4001 quad NOR gate, can be included to stop any sleight of hand tricks by the Shark when he (or she) is pressing the buttons. The NOR gates are connected with their two inputs connected to the respective LEDs on the Shark and Mug sides of the circuit. Thus, if the Mug presses the correct button, the respective NOR gate sounds the buzzer. This stops any dirty tricks by the Shark. A. J. Lowe, Bardon, Qld. ($50) Issues Getting Dog-Eared? Keep your copies safe with these handy binders. REAL VALUE AT $13.95 PLUS P & P Available Aust, only. Price: $A13.95 plus $7 p&p per order (includes GST). Just fill in and mail the handy order form in this issue; or fax (02) 9939 2648; or call (02) 9939 3295 and quote your credit card number. 94  Silicon Chip siliconchip.com.au Emergency Lights Controller This emergency lights controller uses a PICAXE micro to provide a number of useful functions. A 12V battery which is permanently on “float” charge powers the circuit. A 3-terminal 5V regulator is used to power IC1 (the PICAXE micro), while the rest of the circuit runs from the battery supply. The presence of mains supply is sensed by relay1; its contacts hold P4 of IC1 low. When the mains power fails, relay1’s contacts open and P4 of IC1 is pulled high. Relay2 is then turned on via Q1, to connect the emergency lights which then stay on for five minutes, unless the over-ride switch (S1) is pressed. This 5-minute period is indicated by LED1 which flashes. This gives the user time to activate the over-ride switch but turns the emergency lighting off to stop the batteries from being expended if no one is home. LED1 goes to steady in the over-ride/lights off mode if the over-ride button is not pressed within the 5-minute period. This allows easy location of the unit. If in the over-ride mode, the controller then toggles the lights on/off until the mains supply is restored. If mains power returns at any time, the controller returns to its standby mode. When the mains power is present, the lights can be tested by pressing switch S1. This turns the lights on for five seconds to test relay operation. If pressed again during this 5-second period, a long test (65 seconds) is initiated. A third press stops the test. The long test is to allow checking of lights in other rooms. When the lights are on, in mains fail mode, the battery voltage is checked via pin P2 and if the battery voltage is getting low, the buzzer chirps slowly, then faster as the battery voltage drops. Pressing the silence button, S2, turns the buzzer off. If the voltage drops to a lower level, the lights are turned off to prevent damage to the battery. As well checking the battery voltage, via zener diode ZD1, P2 also drives the buzzer and responds to switch S2. The zener diode gives a range of 2-3V at P4 for a battery voltage of 11-14V. This translates to an ADC value of 100-150. Due to variations of values in the components, the values used in the code may need changing. This can be done by using programmer debug while reducing the power supply voltage. A white LED is used in the emitter of transistor Q1 to ensure that it is turned off unless it has least 3V at its base. If the battery float voltage is higher than about 13.8V, the transistor will be close to being on and at anything higher it will actually conduct. This can be prevented by increasing the zener voltage or putting another LED in series with the white LED. A red LED will give an extra 1.5V margin. Interrupts are used to detect the operation of the over-ride/ test button. This allows the button to be detected at all times, even if in the middle of a pause. To set the value of the ADC to correspond to your selected alarm voltage, simply use the debug statement in the program to read the value of the ADC while reducing the input voltage to the alarm point. You will need to comment out all statements referring to P0 (pin 7), as these will affect the data being sent out on this pin. You will also need to change the link to the serial out. The software will be available on our website for download. Colin Carpenter, Mosman Park, WA. ($75) siliconchip.com.au October 2007  95 Circuit Notebook – Continued Two novel LED flashers Ordinary red LEDs are normally used as light emitters but they can also be used as photo sensors. A single LED can even function as both a light emitter and a light detector in the same circuit. The basic idea is to flash the LED, using the “on” time to light it and the “off” time to sense the photovoltaic current from the ambient light that the LED “sees” when not turned on. The two circuits presented here demonstrate how one LED can function as both a sensor and an indicator. Circuit 1 functions as a “nightlight” in which the LED stays off in normal light and turns on when the ambient light level drops. The 7555 CMOS timer is configured for monostable operation and triggers when the pin 2 voltage is less than 1/3 of the supply voltage. Resistors R1 and R2 form a voltage divider which keeps the cathode of the LED below the trigger voltage. When the ambient light level is bright enough, the LED will develop several hundred millivolts across it which adds to the R1/R2 junction voltage and drives pin 2 above the 1/3 trigger level. In this state, pin 3 of the 7555 will be near 0V and the 1N914 diode will be reverse biased, allowing the LED photovoltaic current to flow into the pin 2 trigger input. When the ambient light level drops low enough, the LED voltage will fall and pin 2 will be below the trigger level. The 7555 will Looking for real performance? From the publish ers of • Learn about engine management systems • Projects to control nitrous, fuel injection and turbo boost systems • Switch devices on and off according to signal frequency, temp­erature & voltage • Build test instruments to check fuel injector duty cycle, fuel mixtures and brake & temperature Intelligent turbo timer I SBN 0958522 94 -4 TURBO BO OST & nitrous fuel cont 9 78095 8 5229 46 $19.80 (inc GST) NZ $22.00 (inc GST) rollers How engine management works Mail order prices: Aust. $A22.50 (incl. GST & P&P); Overseas $A26.00 via airmail. See www.siliconchip.com.au for ordering details. 96  Silicon Chip then generate a one-shot pulse, the 1N914 will be forward-biased and the LED will light up. At the end of the timing period set by R3 and C1 the monostable will reset and discharge C1, ready for another cycle. The LED will be turned off briefly during this time which allows it to sense the ambient light again. Circuit 2 functions as a “day-light flasher”, whereby the LED flashes in bright light and stays off in low ambient light. The LED operates as a light emitter when the 7555’s pin 3 is high and as a sensor when the output is low. The 7555 is configured for astable operation and flashes the LED via the 1N914 diode as long as pin 4 (reset) is held above about 600mV. If the ambient light is too low, the LED will not generate enough voltage at pin 4 and the 7555 astable will be held in the reset state, the output will stay near zero and the LED won’t turn on. Note that the timer IC in both circuits must be a CMOS type because the circuit operates with very low input currents. Intersil ICM7555 devices were used in the prototypes; other devices may not work in Circuit 2 if the reset voltage required is too high. Geoff Nicholls, Hamburg, Germany. ($65) siliconchip.com.au Adjustable Q for subwoofer equaliser The Subwoofer Controller in the August 2007 issue has just about all the features you could want but inevitably, there is always something else. In this case, it is an adjustable Q control for the parametric equaliser. This would allow the width peak or dip selected by the equaliser to be adjusted, which can be very noticeable, depending on the subwoofer itself and the listening room. The accompanying circuit shows the additional components highlighted in yellow. VR5 is a 100kW linear dual-ganged pot. The separate resistive elements of VR5 and the associated 10kW resistors replace the 47kW resistors in the original circuit. This arrangement gives a Q adjustment range from about 1.3 to about 10. Unfortunately, the extra dualganged pot cannot be fitted into the Save Up To 60% On Electronic Components Great New ET-AVR Stamp Only $19.90 * Includes ATMega128 Microcontroller * Up to 53 I/O Points * 8-Channel 10-bit A/D * Direct In-Circuit Porgramming * Ideal as a Removable Controller Exciting New ET-ARM Stamp * Includes LPC2119 Microcontroller * High-Speed Operation * Heaps of I/O plus CAN, UART, I2C * In-Circuit Programming * Supporting Board Also Available A revolutionary new system that combines circuit design, PCB design, simulation & CAD/ CAM in one complete package for your pc. rom: f o m e d e a fre oncepts.com d a o l n w o D -c e v a w w e n www. Only $24.90 We carry a wide range of Integrated Circuits, Microcontrollers, Capacitors, LEDs and LCDs. All at very competitive prices. www.futurlec.com ssional ve ard & Profe s’. on ‘feature n Stand nces betwee We are your one-stop shop for Microcontroller Boards, PCB Manufacture and Electronic Components. siliconchip.com.au CIRCUIT ! W E N WIZARD rsions click Save Heaps on Components Only $5.90 specified low profile plastic case but can be included if you build the Subwoofer Controller into the case for an accompanying subwoofer amplifier. Philip Chugg, Rocherlea, Tas. ($30) differe To see the IDEAL FOR Schools, TAFEs, Hobbyists & Business Circuit Wizard Standard – $202* & Circuit Wizard Pro – $390*post*incin GST Aust. 555Electronics Australia and New Zealand – for orders or more information, please contact McLaren Vale, SA 5171 Tel (08) 8323 8442 email: bwigley<at>senet.com.au www.555electronics.com.au October 2007  97 Vintage Radio By RODNEY CHAMPNESS, VK3UG Nazi Germany’s Peoples’ Radio (Volksempfaenger) During the 1930s, radio broadcasts served as an important propaganda tool. It was also the era of The Great Depression, so not many people could afford high-priced radios. Nazi Germany’s answer was a series of simple, low-cost “austerity” models. When Adolf Hitler’s National Socialist Party (NSP) came to power in Germany in 1933, things quickly changed – much of it for the worse – in the depression-gripped country. Radio receivers were a luxury item in Germany at that stage, as the manufacturers ran a price-fixing cartel. However, the NSP soon realised that radio could be a powerful propaganda tool and so a cheap radio that the average household could afford was needed. However, they could also see that the average domestic radio of the day could pick up good-quality signals from adjoining countries. As a result, counter propaganda from these adjacent countries could cause German listeners to question what they were being told by the Nazis. The tuning dial in the DKE38 carries numbers rather than station markings. Note the Nazi emblem with the swastika and eagle immediately above the dial. 98  Silicon Chip So the Nazis they faced a dilemma. How could they encourage people to buy sets and listen to German radio broadcasts but not to broadcasts from neighbouring countries? The solution was simple – keeping the price down so that the general population could afford the sets inevitably meant that they would be simple low-performance receivers. Their performance would be inferior to the more expensive sets, so the chances of them picking up good-quality broadcasts from other countries would be minimised. To make absolutely sure that people only listened to German broadcasts, a label would be placed on the sets stating the following: “Be aware – listening to transmissions from across the border is a breach against the national security of our people. By declaration of the Fuhrer, it will be punished with severe jail sentences.” Later in the war, the penalty for listening to “unapproved” radio stations was increased to death in some instances! There were of course other more practical problems to be solved before the “Peoples’ Radio” could become a reality. Unemployment was high in Germany in 1933 and flooding the market with cheap radios could cause many of the established radio manufacturing firms to collapse as sales of their high-priced receivers dwindled. The NSP did not want more unemployment, so they asked a consortium of existing radio manufacturers to design a cheap, simple receiver. All manufacturers would then be directed to make these low-performance sets. And because the sets would be so basic, it was hoped that they would not siliconchip.com.au take sales away from the good-quality, higher-priced receivers. The Volksempfaenger & the Deutscher Kleinempfaenger The first of these receivers was designed and built in 1933 as the model VE301. The “VE” stands for (V)olks(e)mpfaenger, while the “301” referred to the date Hitler became Chancellor of the Third Reich (ie, 30/1/1933). There are several variations on the meaning of the name, but the most common is “Peoples’ Radio”. Later the DKE ((D)eutscher (K)lein(e)mpfaenger) series was produced. The most common translation of this name is “German Small Receiver”. Subsequently, during the Hitler years from 1933-1945, at least 20 variations of the “People’s Radio” were produced. Most models were designed to be used on mains voltages, either AC or DC, in the range 110-240V. However, some sets were designed to run exclusively on DC mains, while others ran exclusively on AC mains. Battery powered variants were also made for people located away from reticulated mains power. It’s worth noting that as time progressed, the original designs became even simpler. This was due to the manufacturers taking innovative steps to cut costs without impairing the performance of the receivers. The DKE38 was quite bland in appearance. The three controls (from left to right) are: aerial coupling, tuning (and band change) and regeneration. Evolution The first AC mains-powered model, the VE301W, used a transformer, which isolated the mains from the circuitry. An RGN354 rectifier was used in a slightly unusual circuit to provide 240V DC to the valve anodes, while an REN904 triode valve was used as a regenerative detector. The regeneration control consisted of a 180pF variable capacitor which was connected from the plate of the valve to the feedback winding on the single tuning coil. In practice, the set would tune both long-wave (150-375kHz) and medium wave (500-1600kHz) frequencies over two bands. The changeover from band to band was accomplished via the tuning control. When a band change took place, the antenna tappings had to be changed as well. The audio output from the regenerative detector was then coupled through a 1:4 (step-up) interstage transformer. siliconchip.com.au This is the view inside the DKE38. The loudspeaker dominates the cabinet. This fed a directly-heated RES164 pentode audio output stage, which in turn fed a high-impedance reed speaker. The claimed sensitivity of the receiver was 1.5mV and the power consumption was stated as 21W. The first DC mains receiver was the model VE301G. Because it ran October 2007  99 the VE301G but there was no power transformer. In addition, the interstage audio transformer was done away with and an RC network (which was cheaper) installed in its place. The antenna connection system was also simpler than in the original sets and it was not usually necessary to alter the antenna tappings when changing bands. Another feature of the receiver was negative feedback between the plates of both stages. All of this simplification did not come at the expense of sensitivity which was specified at 1mW. The set’s power consumption was just 15W. Inside the DKE38 The DKE38 is a transformerless AC/DC set and most of the parts run at lethal voltages. The 3-core mains lead (with the earth lead cut short) is a “ring-in”. Note that tying a knot to anchor the mains cord (as shown here) is now illegal. This is the under-chassis view of the DKE38. Note the swinging antenna coupling at right. The modern capacitor replacements at left look out of place. from DC, this had neither a power transformer nor a rectifier. The valve line-up differed from the VE301W as well, the VE301G using a REN1821 and a REN1823a. In this unit, the valve heaters were connected in series across a 110V supply, while a tapped resistor was added in series with the heaters for higher DC supply voltages. Any rapid irregularities in the supply voltage were filtered using a conventional pi-type filter network consisting of two 4mF capacitors across the mains and an iron-cored choke between the capacitors on the positive line. As 100  Silicon Chip might be expected, the overall circuit configuration was virtually identical to that used in the VE301W. The DKE38 The DKE38 made its appearance some five years later, in 1938. The innovation that had taken place in those five years was quite obvious – it was a cheaper, simpler and capable of operating on either AC or DC mains in the range from 110-240V. This set used two valves – a VY2 rectifier and a VCL11 triode/tetrode. There was still the same filtering arrangement on the mains as used in One of these DKE38 German People’s radios was on display during the HRSA’s recent 25th anniversary celebrations and I was able to take a good look at it. This receiver is quite obviously an austerity model, as it is very much a “plain Jane”. The controls from the left to right are: aerial coupling, tuning (and band change) and regeneration. There is no volume control as such, probably because the receiver isn’t particularly sensitive, plus the regeneration and aerial coupling can achieve a measure of volume control, albeit with some degradation of the set’s performance. An interesting omission is the lack of protection for the speaker, unlike Australian-built sets of the same era which had bars as part of the Bakelite cabinet moulding. In addition, the tuning dial only has numbers on it, rather than the station markings. There was one other interesting feature here – just above the tuning control was an emblem displaying an eagle and a swastika. Did the German people really need reminding of the regime they lived under! The rear of the set is completely covered with a perforated pressedcardboard panel. This panel also carries a few instructions and has information on attaching antennas and an earth to the set. Of course, it is necessary that this cover remain in place, as the DKE38 is a “hot chassis” unit. In other words, mains voltages are present just about everywhere inside the set. In fact, a set like this should only be operated with all covers on or via an isolation transformer. An isolation transformer, for those unfamiliar with them, is used to isolate a receiver’s siliconchip.com.au circuitry from the mains, to make it safer to work on. However, that is not an invitation to be careless. The rear panel also carries what appears to be the remnants of the mains on-off switch (near where the power lead enters the receiver). This is no longer in use in this particular set. The set’s cabinet is reasonably large, considering how little it houses. It measures 24cm high x 24cm wide x 12cm deep and the loudspeaker is the dominant part. The complete unit weighs just 2kg, which is very light. Removing the back cover shows just how simple this set is. On top of the chassis are two valves, a couple of filter capacitors, a tapped wirewound resistor, a coil, a small filter choke, the tuning capacitor and a fuse. The loudspeaker is attached to the inside front of the cabinet. Removing the chassis from the case involves removing two knobs at the front and two screws towards the rear of the set. Turning it over shows that the underside of the chassis carries only a handful of components. Even here, there is Nazi propaganda – most of the original components had the eagle and the swastika marked on them. Unlike other sets of the era, the chassis is made from a phenolic type material. This not only acts as a chassis but also as an insulator for the various components. Apparently, the shielding benefits of a metal chassis were considered unnecessary in a low-cost set such as this, although some “hand capacitance” effects would probably have been evident when tuning. In particular, this could have caused detuning effects or loss of sensitivity during tuning. It may even have caused the set to go into oscillation in some circumstances. The loudspeaker is around 200mm in diameter, which is quite large for such a simple set. However, a large speaker would be more sensitive and would give greater volume than a smaller unit. An additional advantage was that the set was so big that it could not easily be hidden, so the eagle and swastika would always be on display. One unique feature of the speaker is that its frame is made of compressed cardboard. No doubt it was treated and sealed so that it did not absorb moisture, otherwise it would have quickly distorted and caused the siliconchip.com.au Because it is a “hot-chassis” set, the rear of the DKE38 is completely covered with a perforated pressed-cardboard panel. A bird’s-eye view of the top of the chassis. To keep costs down, the chassis was made of a phenolic-type material rather than metal. speaker to malfunction. But why make the speaker frame out of cardboard? The answer is that Germany needed all its steel for use by the military, so these sets used the minimum amount of metal in their construction. Circuit details Fig.1 shows the circuit of the DKE38. The first stage functions as a regenerative detector and it tunes both the long-wave and the medium-wave broadcasting bands. Shortwave was not included, since the aim was to prevent users tuning to distant stations instead of listening to broadcasts from the Nazi propaganda machine. As shown in Fig.1, the antenna October 2007  101 Photo Gallery: Aimaster TRF Console (1931) depending on what mains voltage is available, hence the bias would also need adjustment. The speaker is a high-impedance (balanced armature) type which saves using a speaker transformer. Power supply MANUFACTURED BY TARGAN ELECTRIC PTY LTD (MELBOURNE) in 1931, this 3-valve TRF console receiver was fitted with an 8-inch (20cm) electrodynamic speaker and was housed in a long-legged wooden cabinet, a style that was popular during that era. The valve line-up was as follows: E442 detector; B443 audio output; and 280 rectifier. Photo: Historical Radio Society of Australia, Inc. input consists of three input points to allow for different sized antennas. However, sets with low sensitivity require both an antenna and an earth if they are to work effectively, so an earth terminal was also provided. The input coil is physically isolated from the rest of the circuit to make sure that it does not operate at mains potential. In practice, a swinging-coil arrangement is used to alter the coupling of the input antenna coil to the tuned winding to optimise reception. The tuned circuit is a conventional regenerative arrangement for a triode detector. The regeneration (reaction) is controlled by 180pF variable capacitor, while a 320pF variable capacitor takes care of the tuning. Note that this tuning 102  Silicon Chip capacitor is capable of rotating a full 360° – the first 180° tunes one band, while continued rotation through the second 180° either switches the second secondary winding in or out to tune the second band. This is achieved using a cam, which in turn actuates the switching (a very nifty idea). The detector stage is RC coupled to the audio output stage. This is also quite conventional, although it is interesting to see that negative feedback is provided between the plates of the two valve sections. A 600W adjustable resistor provides the bias for the audio output stage valve and was probably adjusted in the factory when the radio was set to operate on 110, 150 or 240V. The plate voltage will vary The power supply is similar to that used in many AC/DC type sets. The circuit shows that the mains is switched in both leads but in reality, this probably consisted of a linking system that was broken if the back of the set was removed. However, I can’t be sure of this, as this mechanism is incomplete in this particular receiver. As shown, one side goes through a fuse and is followed by an adjustable 600W resistor. This then provides the common “earthy” line for the circuit. On the other line, the voltage dropping resistor to the heaters of the two valves is selected using a “wander” lead. This is then followed by the 30V 50mA heater of the VY2 rectifier and the 90V 50mA heater for the VCL11 triode/tetrode valve before going back to the other side of the mains. One side of the mains is also applied directly to the plate of the VY2 rectifier. The rectified output is taken from the cathode and is fed to the filter network consisting of two 4mF capacitors and an iron-cored choke in a pi filter network. A 10nF capacitor is also wired across the VY2 rectifier to get rid of any high-frequency spikes. In view of its low-cost design philosophy, it initially puzzled me that an iron-cored choke was used in the filter network instead of the simpler and cheaper resistor option used in later domestic radios. In the end, I concluded that they couldn’t use a resistor because the voltage drop across a resistor that was effective enough to act as a filter element would have been too great. In fact, the audio output with a 110V supply is down to just 0.25W, increasing to 1.2W on 240V. High-value electrolytic capacitors were not available in those days either, so the iron-cored choke was a necessity. Miscellaneous The DKE38 receiver was certainly made of lightweight materials, the speaker drive mechanism and the filter choke being the only components with windings and a metal core. It’s an interesting receiver, if only for siliconchip.com.au NOTE: ALL PARTS IN THIS CIRCUIT OPERATE AT LETHAL VOLTAGE Fig.1: the circuit of the DKE38. The first stage functions as a regenerative detector, while the second stage is the audio amplifier. Note that all parts in this circuit, except for the antenna input circuit, operate at lethal voltages. its design philosophy. It’s also interesting to note that the Telefunken VY2 and the VCL11 valves were designed specifically for the German Peoples’ Radios. Other countries also produced “austerity type” radios, one example being the Austrian R2 set of 1939 – see photo. It wasn’t as austere as the German set though, as the R2 was a 6-valve superhet which covered the long-wave, medium-wave and shortwave bands. The German army later used this model extensively. Britain also had its own equivalent. Called the “Utility Receiver”, it was built by various manufacturers to a government-approved standard. Basically, it was an austerity model that used standard components and a simple design to economise on scarce raw materials and to make repair easier. However, despite its simple design, it was quite capable of picking up the Nazi broadcasts, a practice that was discouraged but not forbidden. Summary The set featured in this article was obtained by its current owner, Ian Johnston, after a previous owner had carried out some “restoration” work. Unfortunately, that owner had not siliconchip.com.au The Austrian-made R2 is a 6-valve multi-band superhet that was used extensively by the German army during WW2. taken the time to disguise several new components inside the old component cases and the new parts look out of place in the chassis. The mains lead was also replaced with a 3-core item, which is out of place on such a set since the earth lead is just cut off anyway! In fact, using a twin lead and an isolation transformer is the safest way of running an AC/DC receiver like this. Even so, a high-voltage insulation test between the antenna/earth connections and the mains should be carried out before even trying to use a set like this, in case of an insulation breakdown. These old AC/DC sets can SC be death traps for the unwary! October 2007  103 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 Repairs to Sony Betacam VCR I have a Sony Beta SL-C80AS PAL VCR that has faulty audio (wow & flutter and some distortion). I am looking for someone who could service it for me. I am 90km from Gosford, so do not have easy access to specialised service outlets. I have a pile of Beta tapes that I wish to dub to DVDs. I would appreciate any help you can offer. (P. K., Gosford, NSW). • We have spoken to our Serviceman and he says that unfortunately you have left it too late. There are few parts and even fewer technicians interested in fixing complex 20+ year old Betas. His advice is to change the pinch roller, roughen the upper and lower head drums to prevent stiction (without damaging the heads) and make sure the reel brakes are not stuck on. In addition, clean the ACE head (make sure it is not worn out) and change the electros in the power supply. Appliance energy meter for the USA I live in the USA and your construction article for the Appliance Energy Meter (SILICON CHIP, July/August 2004) doesn’t make it clear whether it is suitable for 115VAC. Please clarify. (B. M., Minneapolis, USA). • We designed the Energy Meter for the Australian and New Zealand 240VAC 50Hz mains and it should work as well for the European 220VAC 50Hz mains. However, it is not suitable for use with 115VAC 60Hz because: (1) the power supply would be too low and a different mains transformer would be required; (2) the unit is calibrated for 240V and up to 15A; (3) the input voltage measurement divider requires changes for 115V and; (4) the software would require rewriting. Sorry, it cannot be used in your country. Searching for transistor equivalents Some time ago, I bought a publication about semiconductors (transistors, thyristors, diodes, ICs and so on) in an attempt to assist in locating compatible semiconductors (mostly transistors). While searching for a PN2222 NPN type transistor, I opened this book only to find I need to know the type (for example 1N1907 or 2SC1556 or 74177) to alphabetically locate this particular semiconductor. Where is this information as to semiconductor types so that I can try to figure out this “Up-To-Date Worlds Semiconductors” book please? (C. H., via email). • The best way to solve such problems is to do a Google search. This will give you the device specs and then you can decide on a suitable substitute. We would suggest a BC547 although you still need to check that it has the same pinouts. If not, you may have to bend the transistor’s leads to match. Volume control for the SC480 amplifier I am interested in building the SC480 amplifier as described in the January & February 2003 issues of SILICON CHIP. The question is: where and how do you provide volume control for the output? Is there another module required for this? (M. P., via email). • Yours is a very common question, pertaining to many amplifier modules that we have described over the years. The approach is very simple and has been most recently illustrated in the direct volume control connection for the Stereo 20W Class-A Amplifier - see page 75 of the September 2007 issue. You just hook up the volume control pot (10kW log) to the input signal. No extra module is required. Inverter transformer for the valve preamp I have been unable to get the 12AX7 valve audio preamplifier project (SILICON CHIP, November 2003) from Jaycar electronics as they no longer stock this kit. I am confident of finding most of the parts on the list except the Starship Enterprise Door Sounder Mods For Switch Operation I have recently finished building the Starship Enterprise door sounder (SILICON CHIP, June 2006) and it works fine. However, I noticed space on the PC board for two capacitors, two 220kW resistors, a JP1 jumper and a terminal block TB2 marked S3-S4. Does this mean the unit can be operated from an extra set of switches? Also, with out trying to be disre104  Silicon Chip spectful, if it was difficult simulating the sound, why not simply record the original sound from the TV show onto the chip? (G. G., Wollongong, NSW). • As you have guessed, the Starship Enterprise door sounder can be arranged to operate from an extra set of switches, by adding the extra components. When this is done though, there must be a recorded sound for each of the four switches, so each sound can use only one quarter of the chip’s memory. In other words, the project then can deliver one of four short sounds, instead of one of two longer sounds. The sounds that were finally programmed into the recorder chip for this project were in fact taken from a recording of the TV show, as we did find it too hard to simulate. siliconchip.com.au Input Offset Adjustment For Class-A Amplifier About a year ago, I built your old version of the class-A amplifier (SILICON CHIP, July & August 1998). I have since been using it every day connected to Quad ESL 57 electrostatics without any problems and with plenty of volume. So I think that your new 20W version should be quite sufficient as far as power goes. Also, if you use amplifiers with higher power than 25W, a protection circuit must be fitted as Quad ESLs, as far as I am aware, are only rated at 25W RMS. If volume is low with ESLs, then it is most probably due to the EHT block, which requires a service. In your reply to a letter in the July 2007 issue (page 98) you spoke of a trimpot in the emitter of the differential input stage and diodes connected across both transistors so the new version 20W class A could be used with ESLs. Is all this really necessary, especially as mine, admittedly the old version, works perfectly and sounds great? Incidentally, it is even better than a 25W per channel single-ended valve amplifier using 300B output valves that I also have. (C. A., via email). converter transformer (T1). Altronics looked for it but they had a different type of core and I’m not sure if the same thing can be achieved using it instead. Also in the article it is mentioned that the secondary winding is done in two layers but are these two layers wound in opposite directions from each other? I would appreciate it if you could tell me where I can obtain the converter transformer (T1) or if there is an alternative solution? (A. A., via email). • Both the preamplifier and inverter PC boards (board numbers 01111031 & 01111032) for this project can now be obtained from RCS Radio Pty Ltd. Phone (02) 9738 or www.rcsradio. com.au. The original article gave fairly complete details for winding the converter transformer and you could probably wind it on a similar core if this is all siliconchip.com.au • Strictly speaking, any solid-state amplifier driving transformer loads (such as your ESLs) should have the circuit features referred to. If you measure the offset voltage of your amplifier and also the DC resistance of the transformer’s primary winding (ie, the DC resistance across your ESL’s speaker terminals), you can calculate the DC current which flows in the transformer primary. For example, if your amplifier’s DC output voltage is +50mV and the transformer’s primary resistance is 100mW, then the standing current will be 500mA. This will lead to overheating and distortion in the amplifier and will also cause additional distortion in the transformer due to the gross shift in its B-H curve. Ideally, any DC current through the transformer should be at an absolute minimum. In fact, even the suggested DC output offset value of ±5mV could result in a DC current of 50mA. Ideally, any DC current in the primary of the ESL’s transformer should be no more than a few milliamps. To measure your amplifiers’ DC output offset voltages, just connect your digital multimeter across the speaker terminals (with the speaker disconnected), for each channel. Use the 200mV DC range and the reading should normally be within less than ±50mV DC. For example, our new prototype class-A modules, as mounted in the chassis pictured last month, have DC output offsets of +7mV and +44mV DC. As built, your class-A amplifier might have an output offset voltage of only a few millivolts, in which case there is no problem. But it could easily be a lot more. And if you like playing classical music at even reasonable levels, you do run the risk of running the amplifier into clipping and the subsequent risk of damage due to transformer-induced spikes. Occasional modest clipping may not cause a problem but heavy clipping carries a large risk. To provide an offset adjustment, connect a 100W trimpot between the two 100W emitter resistors for Q1 & Q2. The method is shown in the circuit of the Studio 350 amplifier featured in the January 2004 issue. We must emphasise, however, that we have not tested the class-A amplifier module with this modification. that you can obtain, assuming it’s of roughly similar size. The two layers of the secondary winding are wound in the same direction around the centre leg of the core (ie, both clockwise), but with the turns progressing from the start end to the halfway point in the first layer, and then back to the start for the second layer. The main point to watch is that after winding the first layer, you cover it with a layer of PVC tape before winding the second layer over it. up for use in acoustic guitars, violins etc, we would make the following changes to one input of the mixer. Assuming this is input 1, omit Rm1a and link across Rm1b; omit Rin1 and the 2.2mF input coupling capacitor; make Rza1 & Rza2 both 10MW; make Rf 4.7kW and Cf 1nF. If you find that you need more gain, increase the value of Rf. Mixer mods required for acoustic guitar pickup I recently built the headphone amplifier and preamplifier featured in the October 2005 issue. I have used two different brands of 2200mF capacitor in the power supply and the voltage is 0.1V lower on the positive output than the negative. Is this a problem? Would this contribute to the sound being slightly louder in one channel than the other? The intensity of the Referring to the Versatile 4-Input Mixer described in the June 2007 issue, what component values would you suggest for an under-saddle piezo pick-up (passive) in an acoustic guitar? (J. G., via email). • To accommodate any ceramic pick- Preamp gain varies between channels October 2007  105 Questions On The Programmable Ignition I have a few questions regarding the Programmable Ignition MkII kit (March, April & May 2007). First, where can the Sensym map sensor be purchased? Second, are you able to explain the setting “response to low RPM” to me in more detail? How does this function actually work and how does the RPM setting you define play its part? The description in the manual on exactly what this setting does is very vague. Thirdly, does the max RPM act in any way as a rev limiter? Will it drop sparks if you exceed this RPM or what happens? (J. P., via email). • The full details on where to buy the Sensym sensors was published in the April 2007 issue of SILICON CHIP on page 76. The Sensor can be obtained from Farnell (www.farnellinone.com.au) or RS Components sound seems to slightly roll from one channel to the other but apart from that I am happy with the results. (A. R., via email). • Slight differences in the capacitors and the supply rails should have no effect on the preamplifier’s performance. However, it should not be audibly different in the left and right channels. This suggests that some resistor values (www.rsaustralia.com). The actual sensor depends on whether you have turbo or supercharger boost. The details are on the abovementioned page. Response to low RPM means the RPM below which the calculation for timing is made between each trigger edge before the spark is triggered. This is to speed up the response at low RPM where engine revs can change very quickly. In practice, the setting only needs to be at or below the idle RPM. No engine RPM limiting is provid­ ed. The max RPM refers to the mapping limit of the advance curve. There is no easy way to provide limiting using spark control without richening the mixture and making the engine prone to backfire. This could be more detrimental to the engine than over-revving. may not be the same in both channels or that the ganged volume control does not track well in both channels. 100Hz ripple due to faulty capacitor Could you please explain what the likely causes of ripple current in amplifiers would be? I’m having 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. 106  Silicon Chip problems with an old “Electronics Australia” 300W subwoofer amplifier that I’ve built. This amplifier module is part of a pair that to date has worked flawlessly but after a period of about three months of inactivity, one has now developed what I suspect to be ripple current hum (I’m pretty sure it is not an earth loop, as nothing has been changed in the wiring). I have about 50,000mF filtering across each rail. If one of the filter capacitors has died and caused an imbalance, would this be the source or something else? I’m not sure if this is the case though, as there’s no switchoff thump when the power is removed. (P. S., via email). • If your amplifier has suddenly developed ripple current symptoms (ie, audible 100Hz buzz), the most likely causes are a poor solder joint or a capacitor (or capacitors) which has developed high internal resistance. Lead length limitation on keypad alarm I am building the Keypad Alarm as published in the April 2003 issue of SILICON CHIP. I intend situating the keypad & circuit board some distance apart and note that you say that the maximum lead length should not exceed 200mm (page 34, Fig.4). 400mm would suit me better. How important is this limitation in lead length? (N. W., via email). • The limitation on the length of wire connecting the keypad to the main PC board is due to the possibility of false keypad detection with longer leads. When using longer leads, we would recommend adding pull-up resistors at the four inputs to the keypad (RB4, RB5, RB6 and RB7 at pins 10, 11, 12 and 13 of IC1). The resistors can be 1kW but for lengths over 1m, a lower value may be necessary. Values down to 330W may be required to prevent false keypad entry detection. The pull-up resistors connect to the +5V supply (available at REG1’s output and at pin 14 of IC1). LEDs for Video Reading Aid I am gathering together the parts required to build the Video Reading Aid described in December 2005. The kit looks to be quite useful, as commercial siliconchip.com.au Notes & Errata Conversion From RPM To Frequency For Engines With One To 12 Cylinders Cylinders 1000 RPM 4000 RPM 4500 RPM 5000 RPM 5500 RPM 6000 RPM 1 (4-stroke) 8.33Hz 33.33Hz 37.5Hz 41.67Hz 45.83Hz 50Hz 2 (4-stroke), 1 (2-stroke) 16.67Hz 66.67Hz 75Hz 83.33Hz 91.67Hz 100Hz 3 (4-stroke) 25Hz 100Hz 112.5Hz 125Hz 137.5Hz 150Hz 4 (4-stroke), 2 (2-stroke) 33.33Hz 133.33Hz 150Hz 166.67Hz 183.33Hz 200Hz 5 (4-stroke) 62.5Hz 250Hz 281.25Hz 312.5Hz 343.75Hz 375Hz 6 (4-stroke), 3 (2-stroke) 50Hz 200Hz 225Hz 250Hz 275Hz 300Hz 7 (4-stroke) 218.75Hz 875Hz 984.38Hz 1.09kHz 1.20kHz 1.31kHz 8 (4-stroke), 4 (2-stroke) 66.67Hz 266.67Hz 300Hz 333.33Hz 355.66Hz 400Hz 9 (4-stroke) 75Hz 300Hz 337.5Hz 375Hz 412.5Hz 450Hz 10 (4-stroke), 5 (2-stroke) 83.33Hz 333.33Hz 375Hz 416.67Hz 458.33Hz 500Hz 11 (4-stroke) 91.67Hz 366.68Hz 375Hz 416.67Hz 458.33Hz 500Hz 12 (4-stroke), 6 (2-stroke) 100Hz 400Hz 450Hz 500Hz 550Hz 600Hz Rev Limit Controller, April 1999: the section describing the setting of the rev limits on pages 87-88, by revving the engine in a low gear while travelling along a quiet street and while a passenger makes the adjustments, is no longer recommended. Instead, we advocate using a signal generator to set each limit point. The signal generator needs to have at least a 5V peak-to-peak square wave output. A suitable gen­ erator is the Jaycar QT-2302. The signal from the generator is applied between the low voltage input and the 0V terminals of the Rev Limit Controller. Readers who have built the reluctor input version readers cost in excess of $3000. It is a pity that none of the parts retailers has put the kit together. The kit specifies high brightness LEDs. What mcd and mW output were used in the kit that you constructed? I have located some that range up to siliconchip.com.au will need to add ZD2 and the two 1kW resistors that are associated with the low-voltage input circuit. The two 1kW resistors are those just above ZD2 on the overlay diagram (Fig.6). The above table shows the frequencies that correspond to engine RPM for various engine types. Select your engine and the RPM you require for each setting. Now set the frequency generator to the frequency shown and adjust the trimpot associated with the lamp to just light at that frequency. For the Jaycar QT-2302, set the frequency range to x1 for up to 1.5kHz, with the amplitude set fully clockwise 18,000mcd and 120mW. I suspect that these would consume too much power for the intended 12V power supply? (D. M., via email). • It sounds as if you are proposing to use the same 5mm white LEDs that were used in the prototype Reading and with the square wave setting and 0dB attenuation. Note that the Jaycar QT-2302 has frequency adjustments in steps rather than as a continuous range of adjustment. For this generator, select the frequency that is closest to the one you want. If the RPM you require is not shown in the table, refer to the 1000 RPM values in the table. The frequency value can then be scaled up for your desired RPM. For example, if you require the Rev Limit Controller to switch at 6200 RPM for a 4-cylinder 4-stroke, multiply the 33.33Hz value for 1000 RPM by 6.2. The result is 206.65Hz. Aid. They are available from Jaycar as ZD-0195 and have a maximum power rating of 120mW and a typical output of 18,000mcd at 30mA. These LEDs provide more than enough lighting in the Reading Aid, where they are run at a current level of around 20mA. SC October 2007  107 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* 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. 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. 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, PROGRAMMING 32-bit MICROCONTROLLERS IN C By Luci di Jasio (2008) $79.00* 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. PRACTICAL GUIDE TO SATELLITE TV 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. 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. 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. See Review March 2010 See Review Feb 2004 SWITCHING POWER SUPPLIES A-Z 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. 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. 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 Ian Hickman. 4th edition 2007 $61.00* by Douglas Self 2nd Edition 2006 $69.00* by Carl Vogel. Published 2009. $40.00* 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 PAYPAL (24/7) INTERNET (24/7) MAIL (24/7) PHONE – (9-5, Mon-Fri) eMAIL (24/7) FAX (24/7) To ilicon Chip Use your PayPal account www.siliconchip. Callsiliconchip.com.au (02) 9939 3295 with silicon<at>siliconchip.com.au Your order and card details to Your order to PO Box 139 Place108  S com.au/Shop/Books silicon<at>siliconchip.com.au Collaroy NSW 2097 with order & credit card details with order & credit card details (02) 9939 2648 with all details Your You can also order and pay for books by cheque/money order (Mail Only). Make cheques payable to Silicon Chip Publications. Order: 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* 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. 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. 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, PROGRAMMING 32-bit MICROCONTROLLERS IN C By Luci di Jasio (2008) $79.00* 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. PRACTICAL GUIDE TO SATELLITE TV 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. 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. 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. See Review March 2010 See Review Feb 2004 SWITCHING POWER SUPPLIES A-Z 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. 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. 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 Ian Hickman. 4th edition 2007 $61.00* by Douglas Self 2nd Edition 2006 $69.00* by Carl Vogel. Published 2009. $40.00* 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 PAYPAL (24/7) INTERNET (24/7) MAIL (24/7) PHONE – (9-5, Mon-Fri) eMAIL (24/7) FAX (24/7) To siliconchip.com.au October 2007  109 Use your PayPal account www.siliconchip. Call (02) 9939 3295 with silicon<at>siliconchip.com.au Your order and card details to Your order to PO Box 139 Place com.au/Shop/Books silicon<at>siliconchip.com.au Collaroy NSW 2097 with order & credit card details with order & credit card details (02) 9939 2648 with all details Your You can also order and pay for books by cheque/money order (Mail Only). Make cheques payable to Silicon Chip Publications. Order: ALL TITLES SUBJECT TO AVAILABILITY. PRICES VALID FOR MONTH OF MAGAZINE ISSUE ONLY. ALL PRICES INCLUDE GST MARKET CENTRE Cash in your surplus gear. Advertise it here in Silicon Chip. CLASSIFIED ADVERTISING RATES Advertising rates for these pages: Classified ads: $27.00 (incl. GST) for up to 20 words plus 80 cents for each additional word. Display ads: $49.50 (incl. GST) per column centimetre (max. 10cm). Closing date: 5 weeks prior to month of sale. To book your classified ad, email the text to silicon<at>siliconchip.com.au and include your credit card details, or fax (02) 9939 2648, or post to Silicon Chip Classifieds, PO Box 139, Collaroy, NSW, Australia 2097. Enclosed is my cheque/money order for $­__________ or please debit my o Visa Card   o Master Card Card No. Signature­­­­___­­­­­­­­__________________________ Card expiry date______/______ Name _________________________________________________________ Street _________________________________________________________ Suburb/town ______________________________ Postcode______________ FOR SALE More control solutions for you: NEW Radio Modules: Zigbee Radio Modem 1km, Bluetooth Serial Modem 100m. NEW Ethernet Modules: Ethernet to RS232/RS422/RS485 1, 2, 4 & 8-port Modules. NEW Protocol Gateways: Lonworks to Modbus, Profibus to Modbus, Can (J1939) to Modbus, AB-DF1 to Modbus, Hart to Modbus and more. NEW M325 Microstepping Bipolar Stepper Driver only $99. NEW 500oz-in plus Stepper Motor: may not be the fastest motor on the block but it has real grunt. NEW USB 8 Relay and 4 isolated input card. NEW 20A DC Motor Speed Con­troller. Low Cost Dual DC Amplifier Kit: per­ fect for Data Acquisition. Amplify signals from 1.5 to 10 or reduce signals by a factor of 0.7 to 0.1. Electronic Thermostats with digital 110  Silicon Chip temperature display, 2 control relays. Can be used in heating and cooling. NTC thermistor or J T/C or Pt100 sensors. Isolated and Non Isolated RS232 to RS485 converters. USB to RS422/RS485 converter with 1500V isolation, RTS or Auto Data Flow control. Signal Conditioners – non isolated and isolated: Convert thermocouples, RTDs to 4-20mA or 0-10V. Fully programmable. Stepper Motors: we have a selection of Stepper motors for hobby and high torque CNC applications. DC Motors for both hobby and high torque applications. DC, Stepper and Servo Motor controller kits. Serial and Parallel Port relay controller cards. PIC MicroProgrammers: serial and USB port operated. Switch Mode, Battery Chargers and DC-DC converters. Full details and credit card ordering SPK360 3/5/06 1:10 PM Page 1 20 years experience! HI-FISPEAKER REPAIRS YOUR EXPERT SPEAKER REPAIR SPECIALISTS Specialising in UK, US and Danish brands. Speakerbits are your vintage, rare and collectable speaker repair experts. Foam surrounds, voice coils, complete recone kits and more. Original OEM parts for Scan-Speak, Dynaudio, Tannoy, JBL, ElectroVoice and others! SPK360 Phone:______________ Fax:______________ Email:___________________ tel: 03 9647 7000 www.speakerbits.com available at www.oceancontrols.com.au Helping to put you in control. AMPLIFIER BUILDERS: ezChassis® pre-punched cabinets make all your DIY amplifier projects easier and professional looking. Matching heatsinks and hardware. www.designbuildlisten. com LEDs! New Osram surface mount range, easy to handle and can even be used through-hole! NOS standard and superbright brand name LEDs from just siliconchip.com.au ELNEC IC PROGRAMMERS High quality Realistic prices Free software updates Large range of adaptors Windows 95/98/Me/NT/2k/XP CLEVERSCOPE USB OSCILLOSCOPES 2 x 100MSa/s 10bit inputs + trigger 100MHz bandwidth 8 x digital inputs 4M samples/input Sig-gen + spectrum analyser Windows 98/Me/NT/2k/XP IMAGECRAFT C COMPILERS ANSI C compilers, Windows IDE AVR, TMS430, ARM7/ARM9 68HC08, 68HC11, 68HC12 GRANTRONICS PTY LTD www.grantronics.com.au Do you have wireless problems? Telelink has wireless solutions! If you want the right ‘wireless’ ingredients for a successful project recipe, THINK Telelink! Don’t want to be confused by wireless gobbledegook and confusing buzz words? TALK to Telelink! We will give you honest advice so that you can make the right purchase decision for your OEM low power wireless requirements. Browse our website for more information about our products. If you have any questions speak with a Telelink Communications representative. At Telelink we sell solutions, not problems! 01010101 The world’s lowest cost controller with inbuilt operator interface $164 Developer’s Kit $197 includes programming cable & software Made in Australia - used world-wide splat-sc.com siliconchip.com.au QUEST ® Quest AV® VGA Splitter VGS2 HQ VGA Cables AWP1 A-V Wallplate Come to the specialists... ® www.dontronics.com has 300 selected MS120 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 MD12 Media Distribution Amplifier Products, Specials & Pricelist at www.questronix.com.au fax (02) 4341 2795 phone (02) 4343 1970 email: questav<at>questronix.com.au AV-COMM P/L, 24/9 Powells Rd, Brookvale, NSW 2100. Tel: 02 9939 4377 or 9939 4378. Fax: 9939 4376; www.avcomm.com.au a few cents each. 20 x 2 OLED displays $35. Also LED drivers, kits and all sorts of other stuff. www.ledsales.com.au DVS5c & DVS5s High Performance Video / S-Video and Audio Splitters Quest Electronics® Pty Limited abn 83 003 501 282 t/a Questronix 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°.  12 digital I/O  2 line LCD  5 push buttons  Expandable  Easy to program distribution amps - splitters digital standards converters - tbc's switchers - cables - adaptors genlockers - scan converters bulk vga cable - wallplates Telelink Communications www.telelink.com.au e-mail Jack Chomley – jack<at>telelink.com.au or call (07) 4934 0413 or 0428 199 551 Satellite TV Reception C O N T R O L S VIDEO - AUDIO - PC (02) 9738 0330. sales<at>rcsradio.com. au, www.rcsradio.com.au MicroByte Electronics: PIC Micros – Development Board – Development tools & Components. Phone: (03) 9378 4288. info<at>microbyte.com.au; www. microbyte.com.au hardware and software products available from over 40 world wide manufacturers, and authors. Olimex Development Boards & Tools: ARM, AVR, MAXQ, MSP430 and PIC. Atmel Programmers And Compilers: STK500, Codevision C, Bascom AVR, FED AVIDICY Pro, MikroElektronika Basic and Pascal, Flash File support, and boot loaders. PICmicro Programmers And Compilers: microEngineering Labs USB programmers, adapters, and Basic Compilers, DIY (Kitsrus) USB programmers, MikroElektronika Basic, Pascal, DSpic Pascal Compilers, CCS C, FED C, Hi-Tech C, MikroElektronika C, disassembler and hex tools. CAN: Lawicell CANUSB, CAN232 FTDI: USB Family of IC ‘s. FT232RL, FT2452RL, also BL and others. 4DSystems LCD/Graphics: Add VGA monitor, or OLED LCD to your micro. Simple Serial I/F. Heaps And Heaps Of USB Products: TTL, RS-232, RS-485, modules, cables, analyzers, CRO’s. Popular Easysync USB To RS-232 Cable: Works when the others fail. Only one recommended by CBUS. Money back guarantee. www.dontronics-shop.com October 2007  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. Send to: Retail Operations Manager - Jaycar Electronics Pty Ltd P.O. Box 6424 Silverwater NSW 1811 Email: jobs<at>jaycar.com.au Jaycar Electronics is an equal opportunity employer and actively promotes staff from within the organisation. Advertising Index 555 Electronics............................. 97 Agilent...................................... OBC Altronics.................................. 88-91 Amateur Scientist CDs............... IBC Av-Comm................................... 111 Dick Smith Electronics............ 22-25 Dontronics.................................. 111 Ecowatch.................................... 111 Emona.......................................... 37 FreeNet Antennas...................... 110 Futurlec........................................ 97 Grantronics................................. 111 Harbuch Electronics..................... 79 Hills Industries.............................. 81 Instant PCBs.............................. 112 Jaycar.............. IFC,38-39,51-62,112 JED Microprocessors..................... 5 LED Sales.................................. 110 Microgram Computers.................... 3 Microzed Computers...................... 6 Ocean Controls.......................... 110 Ozzie Sim..................................... 81 DOWNLOAD OUR CATALOG at Quest Electronics....................... 111 www.iinet.net.au/~worcom WORLDWIDE ELECTRONIC COMPONENTS PO Box 631, Hillarys, WA 6923 Ph: (08) 9307 7305 Fax: (08) 9307 7309 Email: worcom<at>iinet.net.au PCBs MADE, ONE OR MANY. Any format, hobbyists welcome. Sesame Electronics Phone (02) 9593 1025. sesame<at>sesame.com.au www.sesame.com.au PCB CARBIDE DRILLS $3.50ea (new). Riston coated Laminate. PCBs made, great prices. acetronics<at>acetronics. com.au Phone (02) 9600 6832. WANTED CUSTOMERS: Truscotts Electronic World – large range of semiconductors and passive components for industry, hobbyist and amateur projects including Drew Diamond. 27 The Mall, South Croydon, Melbourne. (03) 9723 3860. electronicworld<at>optusnet.com.au DISC CUTTING LATHE (audio record112  Silicon Chip Radio, TV & Hobbies DVD............ 66 RCS Radio................................. 111 Richard Foot Pty Ltd.................... 14 ing) Presto, Westrex, Grampian, Neuman etc., acetate blanks and associated gear. John (08) 9279 5407, 25 Darwin Cresc, Morley WA 6062. Silicon Chip Circuit Ideas Wanted Do you have a good circuit idea? If so, sketch it out, write a brief description of its operation & send it to us. Provided your idea is workable & original, we’ll publish it in Circuit Notebook & you’ll make some money. We pay up to $100 for a good circuit idea or you could win some test gear. Silicon Chip Publications, PO Box 139, Collaroy, NSW 2097. RF Modules................................ 112 Sesame Electronics................... 112 Silicon Chip Binders..................... 94 Silicon Chip Bookshop........ 108-109 SC Perf. Electronics For Cars....... 64 Silicon Chip Subscriptions............. 9 Speakerbits................................ 112 Splat Controls............................. 111 Telelink....................................... 111 Tenrod Australia........................... 78 Trio Smartcal................................ 65 Vaf Research.................................. 7 Wagner Electronics...................... 63 Worldwide Elect. Components... 112 PC Boards Printed circuit boards for SILICON CHIP designs can be obtained from RCS Radio Pty Ltd. Phone (02) 9738 0330. Fax (02) 9738 0334. siliconchip.com.au