YouTube Uploaded by nylesteiner on Aug 3, 2011
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This lowpass filter is just like a normal synthesizer lowpass VCF but the cutoff frequency is controlled by the variable resistance of copper oxide when heated by a flame
I built the filter this way just to see how good it would sound when controlled with a flame and copper oxide resistors. The copper oxide resistors are just pieces of ordinary copper wire that had been previously oxidized in a propane flame.
The resonance is difficult to control precisely because of unequal heating and cooling of the two oxidized copper wires.
Another way of doing the same thing would be to just use one flame controlled copper oxide resistance to vary a dc voltage into the VC input of a normal VCF."