This little gem came up for sale on eBay years ago and even had a demo video to go with it. From what I remember there was a very bearded man with a corn cob pipe sitting at his computer spinning these motor wheels and actually creating some interesting sounds! The idea is really simple, if you connect two wires coming out of a small generic motor to an output jack and then spin the shaft you will generate an audible AC current. As the motor is winding down it the pitch will decrease and the sound fades out. Not much to it, but a neat little trick never-to-less.
This post was submitted by circuitmaster.