Tactical Tinkering

Sous-vide is a method of cooking where food is placed in a plastic bag which is then placed in a water bath at a precisely controlled temperature, until the temperature of the food reaches equilibrium with the water bath. Supposedly, the juiciest, most succulent food you've ever tasted results. The catch? These water baths cost hundreds of pounds. But with just a slow cooker and our trusty Arduino (and a temperature sensor and a relay), we should be able to build our own for a fraction of the price!

With air conditioning and fridges literally everywhere these days, we don't give the difficulty of "cooling things" a second thought. A Peltier module is a fascinating little device which does exactly what a fridge does – removes heat from one place and pumps it to another place, except less efficiently. In particular, when we pass a current through the module one side gets hot, and the other side gets cold. It even works the other way around as a thermoelectric generator, if we heat up one side and cool down the other (albeit at only about 5% efficiency).

I've always had an interest in electromagnetism; an interest cultivated during my degree, where I discovered the fantastically elegant mathematical theory behind it. Now I'm looking forward to getting stuck in, perhaps initially by building something to the tune of those on this excellent website: www.OtherPower.com, before experimenting with my own generator designs (and the flipside – motors!). Unfortunately this is really where some specialist machinery is necessary – an oscilloscope at the very least. (Which aren't cheap.)

There's something remarkably satisfying about an engine powered by something as fundemental as the temperature difference between "a hot thing" and "a cold thing". A stirling engine is one example of such a heat engine, and works by the simple fact that a gas expands when it's heated, and compresses when it's cooled. My first attempt is likely to be of the candle-powered "tin can" variety. (See Google.)

There's only so much fun you can have turning an LED on and off before it gets boring. Luckily there are a few things you can do to spice up their entertainment value, such as throwing a whole load of them together in cube form. An LED display is one thing, but forming them into a cube really does add a wole new ... well, dimension!

Arduino: play around with accelerometers.