Yoren

Synthesizer that makes its noise audible by creating a plasma arc in the air. I’m planning to make two versions: The first one will modulate an analog input signal on a signal around 20kHz. This signal will be transformed from 12V to high voltage in a flyback transformer. I expect the high voltage to be in the order of 20.000 V, but i didn’t measure it. Applying the rule of thumb of a breakdown voltage of 1MV/m i will be able to produce sparks of 2cm. Because the pulses are modulated, and the carrier frequency is above the hearing threshold, the arc will reproduce the sound that is present at the audio input of the control circuit. The carrier frequency can be adjusted with a pot to match the resonance frequency of the transformer for a larger and cleaner spark. With another pot the modulation depth can be set.

The second idea uses another control circuit, which doesn’t modulate an audio signal, but pulses directly at the desired frequency for a given note. A midi-in signal is transformed into a pulsed signal, just like in a normal monophonic synth. Maybe I can even produce polyphonic sounds with some clever programming.

I don’t know it is will work just as good as the modulated design, because it doesn’t operate at the resonant frequency of the flyback. Also the arc will be have to be smaller because there’s no continuous arc in between two notes. In this time the ionized (conducting) air will have time to diffuse, requiring a smaller gap between cathode and anode for recreating the arc at the start of a new note.

The former design can also be realized in the form of a Jacob’s ladder. The spark will start at the bottom, where the distance between anode and cathode is smallest. Once the plasma has been created, it will warm up, causing it to move upwards. The higher the spark rises, the larger the distance between the electrodes becomes. At a certain height the distance is too large to be bridged and the arc will broken. The process will start over at the bottom side. All sound you hear in the video below is created by the plasma itself. There’s no music playing in the background.

Started in July 2010.