61002 [Microcontrollers & Embedded • Analogue • Audio• Digital • Test & Measurement] January 2011 AUS$ 14.50 - NZ$ 17.50 - SAR 102.95 £ 4.80 HI ENERGETIC ✚ Energy Saving Tips edition www.elektor.com Cardiac Monitor Your ECG by ZigBee Nixie Tube Thermometer Retro Temperature Display Headphone Amp Music to your ears ✚ Free Energy From known and unknown sources ✚ Economical Energy Harvesting R04 More solar powered circuits 61002 Microcontrollers Integrate Touch Sensing Quickly and Easily With Microchip’s Range of Low Power, Low Cost Solutions Controllers Digital Signal Analog Memory Microchip’s mTouch™ Sensing Solutions allow designers to integrate touch sensing GET STARTED IN 3 EASY STEPS with application code in a single microcontroller, reducing total system cost. - Learn more at www.microchip.com/mtouch Microchip offers a broad portfolio of low power, low cost & flexible solutions for keys/sliders and - Download App Notes & royalty-free source code touch screen controllers. Get to market faster using our easy GUI-based tools, free source code - Order a development tool and low-cost development tools. Capacitive Touch Keys and Sliders Touch Screen Controllers t Extend battery life with eXtreme Low Power MCUs t Fully processed touch coordinates − Proximity sensing in less than 1 μA t Projected Capacitive technology t High noise immunity and low emissions − Multi-touch enabling gestures t Broad portfolio of MCUs lowers system cost − Low cost MCU implementation Enhanced mTouch Capacitive Evaluation Kit - DM183026-2 − 8, 16 & 32-bit PIC® MCUs for Capacitive Touch − Wide operating voltage: 1.8-5.5V (For keys & sliders) − Integrated USB, Graphics, LCD, IrDA, CAN − Low operating current 1.5 mA at − No external components 5V typical t With Metal Over Cap technology you can: t Analog Resistive technology − Projected Capacitive − Use polished or brushed metal surfaces Lowest system cost, easy integration Development Kit - DM160211 including stainless steel and aluminium − Universal 4, 5 & 8-wire solution with − Sense through gloves on-chip calibration − Create waterproof designs − I2C™, SPI, UART or USB interfaces − Deploy Braille-friendly interfaces − Low power “touch to wake-up” feature Analog Resistive Touch Screen Development Kit - DV102011 Intelligent Electronics start with Microchip www.microchip.com/mtouch The Microchip name and logo, the Microchip logo and PIC are registered trademarks and mTouch is a trademark of Microchip Technology Incorporated in the U.S.A. and other countries. All other trademarks mentioned herein are property of their respective companies. © 2010, Microchip Technology Incorporated, All Rights Reserved. ME259BEng/08.10 61002 61002 An energetic edition If I may offer something to ponder or muse over during the winter holiday period, try “how much energy is wasted trying to devise and publish ways to save energy, or get it from sustainable sources 6 Colophon and/or free sources”. I’m sure this conun- Who’s who at Elektor magazine. drum will keep you busy, amused, frus- trated, curious, excited or even hyperac- 8 The PCB Prototyper tive for quite a few days. Let’s hope it does Spreads its Wings not cause anxiety; if so, “there’s solace in the pages to follow”. Whatever direction 9 News & New Products your thinking, pencilling, calculating and A monthly roundup of all the latest in head scratching veers off, it’s a comforting electronics land. thought that you are not alone. When in doubt, write to the editor. 12 mbed Has Landed! In this edition, in line with our cel- Simon Ford’s monthly column on the ebrated 2011 Publishing Plan (it’s on our Elektor/NXP mbed challenge website!), we have a focus on all-things- energy — to which I should add ‘ener- 14 Economical Energy Harvesting getic’. In this edition we cover green Presenting several designs that enable energy, energy harvesting (page 14), circuits to be powered from solar energy. tips to save energy (page 34, some for a good laugh too), and best of all, free 18 Thin FAT energy (page 52). An overview of open source FAT A lot of energy also went into producing fi le system libraries for embedded the other articles in this edition, which applications. should present a nice mix of traditional electronics, microcontrollers and design 24 Nixie Tube Thermometer ideas. The Nixie Tube Thermometer on This is what you get from combining page 24 bridges 50 years in a single a modern microcontroller with a truly project, happily marrying a 21st century classic display. microcontroller and associated program- ming techniques with tube technology 28 Flight Data Recorder from the 1950s. The result is a project A speed and velocity recorder for that’s sure to draw attention when model airplanes, based on our ATM18 placed on your desk or mantelpiece. microcontroller module. Although I do not recommend bypassing your local physician if you’re curious to 34 Energy Saving Tips know your heart condition or other ail- Seventeen ways, some tongue in cheek, ments, why not draw your personal elec- to reduce your energy bill and decrease trocardiogram (ECG) with our Zigbee’d your personal carbon footprint. cardiac monitor (page 56) and send him your personal ECG graphs by email. If you 38 All-Soft-555 suspect you’re too FAT — go to page 18. Two new software utilities allow an ATtiny Myopic in the dark? — page 62. microcontroller to act like the celebrated In closing I congratulate my colleagues 555 timer, with a few features added! in Elektor’s Dutch department on 43 E-Labs Inside: Under Scrutiny: the 50th Anniversary of their edition. Believe it or not, ‘Elektuur’ as it was The Xmega Board called at the time started out in 1961 A look at Mikroelektronika’s latest and was the mother of all international development system for the Xmega versions of the magazine, including this processor. the English one born 14 years later. No ‘Double Dutch’ mockery but a laurel on 44 E-Labs Inside: the front cover of all Elektor editions. Spotted at Electronica 2010 Goed gedaan jochies! Some remarkable products seen last November at the world’s leading Jan Buiting, Editor exhibition on state of the art electronics. 4 12-2010 elektor 61002 Volume 37 January 2011 CONTENTS no. 409 45 E-Labs Inside: Here Comes the Bus! We call on our readers to assist with the development of the Elektor Bus. 24 Nixie Tube Thermometer 48 Low-cost Headphone Amplifi er Nixie tubes have a special charm all of their own. The author’s Sputnik-style Guess what, it’s straightforward, digital clock using the tubes appeared earlier in Elektor, and many variations sounds good and consists of dead on the theme have appeared on the Internet. This digital thermometer, which standard parts only. uses just two tubes, is, well, a little bit different. 52 Free Energy Is it truly possible to generate free energy, or are we deceiving ourselves and others? 56 Wireless ECG In this project Zigbee modules are used to build a system for wireless monitoring of cardiac signals. 48 Low-cost Headphone Amplifi er 62 Groping in the Dark Here we try to find out if a webcam is There have of course been numerous designs for headphone amplifi ers before any good for converting into a night this one, either more or less successful and simpler or more elaborate. The de- vision camera. sign presented in this article is straightforward, sounds quite good and can be built using well-established components. 64 Design Tips: Opamp versus Comparator These devices look very similar with their + and – labels at certain pins, but …. 66 Support Board for Arduino Nano In this article, we’re proposing a motherboard that was originally designed for a robotics application, but which can 52 Free Energy very well be used for other jobs too. Pursuits to make devices move perpetually or to generate energy from nothing 68 Three out of Two Ain’t Bad still occupy the attention of many people. Is it truly possible to generate free Adding a tacho signal to a two-wire fan as energy, or are we simply deceiving ourselves and others? Here we describe a used in PCs. selection of interesting ideas and projects. 72 Notch Filters for Intermediate Fre- quencies Two simple fi lters, one RC and one LC, for suppressing noise in communication receivers. 75 Hexadoku Our monthly puzzle with an electronics 56 Wireless ECG touch. Many devices are available for recording or visualising electrocardiogram (ECG) 76 Retronics: Tandberg Model 5 & signals. The circuit proposed here uses a wireless link as an elegant solution Stereo Record Amplifi er (ca. 1959) to the problem of galvanic isolation, completely eliminating any hazard to the Regular feature on electronics ‘odd & subject. ancient’. Series Editor: Jan Buiting 84 Coming Attractions Next month in Elektor magazine. elektor 12-2010 5 61002 Elektor International Media provides a multimedia and interactive platform for everyone interested in electronics. From professionals passionate about their work to enthusiasts with professional ambitions. From beginner to diehard, from student to lecturer. Information, education, inspiration and entertainment. Analogue and digital; practical and theoretical; software and hardware. ANALOGUE • DIGITAL MICROCONTROLLERS & EMBEDDED AUDIO • TEST & MEASUREMENT Volume 37, Number 409, January 2011 ISSN 1757-0875 Elektor is also published in French, Spanish, American Editorial secretariat: English, German and Dutch. Together with franchised Hedwig Hennekens ([email protected]) Elektor aims at inspiring people to master electronics at any editions the magazine is on circulation in more than 50 personal level by presenting construction projects and spotting countries. Graphic design / DTP: Giel Dols, Mart Schroijen developments in electronics and information technology. International Editor: Managing Director / Publisher: Paul Snakkers Wisse Hettinga ([email protected]) Publishers: Elektor International Media, Regus Brentford, Marketing: Carlo van Nistelrooy 1000 Great West Road, Brentford TW8 9HH, England.