Wind-Up Torch/Flashlight
Approx construction cost US$29
A common problem with small torches is the short life-span both of the batteries and the bulb. The batteries of a small "penlite" torch will commonly last only two to three hours, and many bulb filaments burn no more than a few weeks before fusing. Besides this, torch batteries can sometimes be hard to come by, especially when camping or visiting remote areas.
The idea for a better torch was born a few years ago when the author was caught in a violent tropical storm on a remote dirt track, and his penlite torch rapidly faded and died. With new light emitting diode (LED) technology, it is now possible to build a torch that quite adequately lights the way five to ten meters in front. In fact, since power consumption is so small, it is possible to power the light for a considerable length of time from a few turns of a small generator with a capacitor "reservoir" – the sole source of power for this torch (no batteries).
While the light output of the Wind-up Torch is modest in comparison with some modern torches, it matches several candlepower at medium power, and is thus quite serviceable. It will provide ample light around a camp table, for walking on a footpath, or for reading.
More details on this construction project can be found in the October 2000 issue of EPE Online, the world's first web-delivered electronics and computing hobbyist magazine.
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