Singing Tesla coil

The singing Tesla coil, sometimes called a zeusaphone, thoramin or musical lightning, is a form of plasma speaker. It is a variety of a solid state Tesla coil that has been modified to produce musical tones by modulating its spark output. The resulting pitch is a low fidelity square wave like sound reminiscent of an analog synthesizer. The high-frequency signal acts in effect as a carrier wave; its frequency is significantly above human-audible sound frequencies, so that digital modulation can reproduce a recognizable pitch. The musical tone results directly from the passage of the spark through the air. Because solid-state coil drivers are limited to "on-off" modulation, the sound produced consists of square-like waveforms rather than sinusoidal (though simple chords are possible).