Singing Tesla coil
The Singing Tesla Coil is a variation of a solid state Tesla coil, that has been modified to produce musical tones by modulating it's spark output. The resulting pitch is a low fidelity square wave like sound reminiscent of an old analog synthesizer. The actual method of music production is by means of a PIC microcontroller that is programmed to interpret MIDI data, and output a corresponding Pulse-width modulation(PWM) signal. This PWM signal is coupled to the Tesla coil through a fiber optic cable, and controls when the Tesla coil turns on and off.
The creation of the first device is generally credited to Joe DiPrima, Oliver Greaves with assistance from Steve Ward and Scott Coppersmith. The first known public demonstration was by DiPrima and Greaves, on March 23rd, 2006 at the Enchanted Forest in Austin, TX, for an annual event called "Art Outside".
Since then, DiPrima and Greaves have started a performance group called "ArcAttack"[1], and have continued to demonstrate this technology around the United States and the Netherlands. Some of their more publicized performances have been for Dorkbot at the annual SXSW interactive festival in 2007[2],2008 and 2009[3].