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How this thing works

A project log for Tiny Time-of-Flight Plasma Theremin: the Plasmino

Music evolved! The Theremin for the 21st Century: Plasma speaker, MIDI output, Lasers!

DavidDavid 10/05/2018 at 19:380 Comments

OK, Go the VL53LOX sensors working. Will post a video tomorrow.

Basically it works like this

We generate 2 sets of square wave pulses, at ultrasonic frequencies

1)  ⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍
2) _⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍

They are out of phase, and the generated plasma expands the air.

If we turn this on and off at audio frequencies, we cause vibrations in the air, as the plasma expands and contracts.

1)  ⎍⎍⎍⎍⎍⎍____⎍⎍⎍⎍⎍⎍⎍____⎍⎍⎍⎍⎍⎍⎍____⎍⎍⎍⎍⎍⎍____⎍⎍⎍⎍⎍⎍
2) _⎍⎍⎍⎍⎍⎍____⎍⎍⎍⎍⎍⎍⎍____⎍⎍⎍⎍⎍⎍⎍____⎍⎍⎍⎍⎍⎍____⎍⎍⎍⎍⎍⎍

We can also modulate the volume by changing the duty-cycle, but keeping the frequency the same:

Louder
1)  ⎍⎍⎍⎍⎍_____⎍⎍⎍⎍⎍_____⎍⎍⎍⎍⎍_____⎍⎍⎍⎍⎍_____⎍⎍⎍⎍⎍_____
2) _⎍⎍⎍⎍⎍_____⎍⎍⎍⎍⎍_____⎍⎍⎍⎍⎍_____⎍⎍⎍⎍⎍_____⎍⎍⎍⎍⎍_____

Quiter

1)  ⎍⎍⎍_______⎍⎍⎍_______⎍⎍⎍_______⎍⎍⎍_______⎍⎍⎍_______
2) _⎍⎍⎍_______⎍⎍⎍_______⎍⎍⎍_______⎍⎍⎍_______⎍⎍⎍______

Pretty simple!

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