Circuit bending is the creative short-circuiting of low voltage, battery-powered electronic audio devices such as guitar effects, children’s toys and small synthesizers to create new musical instruments and sound generators. (Wikipedia)

There’s lots of information on circuit bending in an October 13 createdigitalmusic.com article,”Want to Get Started Circuit Bending?”, including a link to Reed Ghazala’s Circuit Bending Primer.

Reed Ghazala is the Father of circuit bending. According to Wikipedia, “Reed accidentally discovered the technique [in 1966]… when he left a toy amplifier in his desk and heard it start to emit sounds comparable to those produced by expensive synthesizers of the day. The amplifier’s casing had been opened, exposing its inner circuitry and allowing it to short circuit when placed against the metal desk.” Reed pioneered it, named it, and has taught it ever since.

There are several short videos at createdigitalmusic.com as well, among them the automated drum pad above (my favorite) by Michael Una, who wrote “Want to Get Started Circuit Bending?”