# How can people do music with Tesla coils?

I saw a lot of videos of Tesla coils doing music on YouTube. And I wonder how can they do that sort of things.

How they can calculate what tone it is going to do? And what are the factors to consider?

• You may be interested in this. Nifty instrument, that. Commented Mar 19, 2012 at 17:14
• I actually have a tesla coils that plays music in my office. It's fun and a sure fire way to impress anybody and make them think you're cool.
– Jim
Commented Aug 18, 2016 at 12:15

In short, the Tesla coil is converting air into plasma, which changes its volume, which causes pressure waves to spread out in all directions (sound).

The sparks are created by a self-oscillating coil, which happens at a high, inaudible frequency (20 to 100 kHz).

The self-oscillating coil, though, is driven by pulses from a spark gap or lower-frequency oscillator, which is in the audible range. By adjusting the frequency of this pulse generator, the rate at which plasma bursts are generated can be varied, which varies the frequency of the sound produced.

I've seen this done in person and it's pretty awesome, but I've always wondered why they play only constant tones. I think they could use something like pulse density modulation to produce any arbitrary waveform and turn the coils into giant loudspeakers.

In a simplified picture a Tesla coil is just a transformer which creates a high voltage, high frequency current between the top part and the grounded bottom.

This transformer receives it's energy from an AC source. If you modulate the AC source (amplitude modulation) the sound created from the sparks of the Tesla coil will also be modulated with that frequency and in the end can be used to play music.

• I know this is a very old answer, but it is not correct. Amplitude modulation is not what is used. The AC source is rectified and converted to DC, and an H-bridge or half-bridge configuration of transistors is used to alternate the current through the primary tank circuit. The transistors are driven by digital sources which modulate the frequency. The AC source is not amplitude modulated. Commented Mar 18, 2017 at 16:57