This is a concept model of a device that could charge low powered devices such as the pebble. Much like many conventional watches, this device takes movements and turns it into power, allowing a device to run indefinitely (in theory) with constant use.

Alike to the way a motor can act as a generator, a speaker can take vibrations or motion and turn it into electricity as well. This model uses a small headphone speaker to generate power.

This model generates a very small amount of electricity (between 200- 1000mV depending on conditions) but a shrunken down and optimized version that does not consist of parts from a 30 year old anemometer could extend the life of the half watt battery.

Technical Details:

A speaker from a pair of earbuds is wired to a 12V to 220V transformer, rectified to DC, and smoothed with a capacitor.

Other notes:

I'm in Mechanical Engineering and cannot code (yet).