John Goldsmith sends in this example of a shake-to-light torch he purchased at a filling Station - it was a cheap offer if you bought enough petrol. Well, he got what he paid for.
"As the closeup photo shows, the power comes from a magnet and coil, being stored in a 0.22 Farad (not microfarad!) capacitor on the PCB. The on/off switch has a little magnet on the slider and a reed switch on the PCB. This maintains the integrity of the watertight housing. The operating magnet is actually some small powerful magnets embedded in a larger lump, presumably steel. A nuisance as it drags all the recent UK coinage out of your pocket. I'm sure the unit would be more efficient with metal springs as end stops - the rubber used seems to absorb all the energy. I recently bought a wind-up 3 LED unit which is much brighter and much longer running (and less embarassing to operate).
Having looked closely, John also discovered a problem with the magnet.
Like most high strength ones it is plated for corrosion protection, but the plating is peeling off. So far it is not impeding operation.
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