Walkabout Generator

You've probably seen those flashlights advertised that have a built-in generator; you shake the flashlight for several seconds, and it charges a little battery that then powers the light.

The type of generator is a simple coil of wire, through which a magnet reciprocates as the flashlight is shaken. There also is some electronics, such as a "bridge rectifier", to do things like turn alternating current into direct current, and so on, but this doesn't take up much space.

Let's take the generator out of the flashlight and attach it to your leg. More specifically, it should be horizontally mounted next to your ankle. It can be smaller than the one in the flashlight, and there can be two, one for each ankle. Total weight will likely be less than half-a kilogram (about one pound).

When you walk, the start-stop jerky motion of your ankles, relative to the ground, will be sufficient to cause the small magnets to reciprocate inside the horizontal (relative to ground when foot at rest) coils. Wires lead from the generators, sprialing decoratively up your legs to a waist-mounted electronics/battery package.

Your plug your iPod or other gadget into that waist-mounted package, of course. And start walking.