Circuit bending is the creative, chance-based customization of the circuits within electronic devices such as low-voltage, battery-powered guitar effects, children’s toys and digital synthesizers to create new musical or visual instruments and sound generators.
Emphasizing spontaneity and randomness, the techniques of circuit bending have been commonly associated with noise music, though many more conventional contemporary musicians and musical groups have been known to experiment with “bent” instruments. Circuit bending usually involves dismantling the machine and adding components such as switches and potentiometers that alter the circuit.
The process of circuit bending involves experimenting with inexpensive second-hand electronics that produce sounds, such as keyboards, drum machines, and electronic learning products. According to Electronic Musician, innovators should only experiment with battery-powered devices, because there is a danger of fire or death from experimenting with mains-powered devices.
The simplest input, and the one most identified with circuit bending, is the body contact, where the performer’s touch causes the circuit to change the sound. Often metal knobs, plates, screws or studs are wired to these circuit points to give easier access to these points from the outside the case of the device.
Since creative experimentation is a key element to the practice of circuit bending, there is always a possibility that short circuiting may yield undesirable results, including component failure. In particular, connecting the power supply or a capacitor directly to a computer chip lead can destroy the chip and make the device inoperable. Before beginning to do circuit bending, a person should learn the basic risk factors about working with electrical and electronic products, including how to identify capacitors (which can give a person a serious shock due to the electrical charge that they store), and how to avoid risks with AC power. For safety reasons, a circuit bender should have a few basic electronics tools, such as a multimeter (an electronic testing device which measures voltage, resistance and other factors). (Wikipedia)