Torch Battery

Principals of Operation of battery-free torch handshake?

I want to know what a battery grip torch light hands-free operation. How is the design of the circuit? Please also help me to find sites that through talking about the operation of it.!

It's just moving a magnet through a coil of wire. the changing magnetic flux creates an electric current through the coil. to be charge a capacitor or a small battery, it is not necessary to shake it to stay that way.

Torch Battery

Torch Battery