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Practical Electronics Editorial offices Practical Electronics Electron Publishing Limited 1 Buckingham Road Brighton East Sussex BN1 3RA Tel 01273 777619 Mob 07973 518682 Fax 01202 843233 Email pe<at>electronpublishing.com Web www.electronpublishing.com Advertisement offices Practical Electronics Adverts Tel 01273 777619 1 Buckingham Road Mob 07973 518682 Brighton Email pe<at>electronpublishing.com East Sussex BN1 3RA Editor Matt Pulzer General Manager Louisa Pulzer Digital subscriptions Stewart Kearn Tel 01202 880299 Online Editor Alan Winstanley Web Systems Kris Thain Publisher Matt Pulzer Print subscriptions Practical Electronics Subscriptions PO Box 6337 Bournemouth BH1 9EH Tel 01202 087631 United Kingdom Email pesubs<at>selectps.com Technical enquiries We regret technical enquiries cannot be answered over the telephone. We are unable to offer any advice on the use, purchase, repair or modification of commercial equipment or the incorporation or modification of designs published in the magazine. We cannot provide data or answer queries on articles or projects that are more than five years old. Questions about articles or projects should be sent to the editor by email: pe<at>electronpublishing.com Projects and circuits All reasonable precautions are taken to ensure that the advice and data given to readers is reliable. We cannot, however, guarantee it and we cannot accept legal responsibility for it. A number of projects and circuits published in Practical Electronics employ voltages that can be lethal. You should not build, test, modify or renovate any item of mains-powered equipment unless you fully understand the safety aspects involved and you use an RCD (GFCI) adaptor. Component supplies We do not supply electronic components or kits for building the projects featured, these can be supplied by advertisers. We advise readers to check that all parts are still available before commencing any project in a back-dated issue. Advertisements Although the proprietors and staff of Practical Electronics take reasonable precautions to protect the interests of readers by ensuring as far as practicable that advertisements are bona fide, the magazine and its publishers cannot give any undertakings in respect of statements or claims made by advertisers, whether these advertisements are printed as part of the magazine, or in inserts. The Publishers regret that under no circumstances will the magazine accept liability for non-receipt of goods ordered, or for late delivery, or for faults in manufacture. Transmitters/bugs/telephone equipment We advise readers that certain items of radio transmitting and telephone equipment which may be advertised in our pages cannot be legally used in the UK. Readers should check the law before buying any transmitting or telephone equipment, as a fine, confiscation of equipment and/or imprisonment can result from illegal use or ownership. The laws vary from country to country; readers should check local laws. Practical Electronics | December | 2023 Volume 52. No. 12 December 2023 ISSN 2632 573X Editorial Amazing electronics It’s so easy to take electronics for granted, even though it is one of the most extraordinary technological and scientific marvels ever created. In just a few decades we have progressed from thermionic tubes to integrated circuits boasting features measured in nanometres. We know it’s amazing and yet we so quickly get used to the pace of change that it takes a lot to impress us. I recently had reason to consider this when I bought an Apple Watch, principally for health reasons. First, a little background: my doctor had told me that I needed to lose weight and do more exercise. I enjoy cooking as much as I dislike exercise, so the thought of eating less and exercising more was not welcome, but the doctor was serious and warned me that sooner or later I’d need to do this, or it would affect my health. He suggested a regime based on calorie-controlled, but nutritious, shakes and a choice of exercises. A friend suggested I get some kind of sports watch to track my exercise. So, armed with some pretty unappetizing shakes, a watch and not much of a clue about exercising I decided to turn this into a personal project to find out just how good a job modern electronics makes of monitoring the human body. To be honest, I wasn’t that optimistic. A background in instrumentation engineering had taught me that measuring even welldefined straightforward parameters such as speed, temperature and pressure takes a lot of skill and effort if you want to get good, reliable results. Measuring the kilocalorie (kcal) burn of the human body sounded horribly complicated and error prone, but perhaps it would be fun to find out if the current state of the art of ‘wearables’ justified all the claims made for them. My plan was simple. The shakes were designed to provide a specific number of kcals per day, my watch’s blood flow / oxygen sensors, accelerometers and gyroscopes, coupled with some (hopefully) sophisticated motion and blood analysis software would tell me how many kcals I had burned. The resulting mathematics was simple: 7,700 kcals represents 1kg of body mass lost (or gained) depending on whether you eat more or fewer kcals than you exercise. Well, the results are in, and I am beyond amazed. My watch is incredibly accurate. Over six weeks I measured and logged my data very carefully. Everything I ate was converted into kcals and subtracted from what my watch had told me I done in terms of exercise. I compared the results with my electronic bathroom scales (a good set made by a reputable company), and the watch was better than 90% accurate. I find that extraordinary. A tiny piece of electronics resting on my wrist can analyse my movement and blood (non-invasively) and from that generate extremely accurate data of what I am doing. Matt Pulzer Publisher 7