The crazy fiddler

synaesthesia

This is something I discovered by accident when playing with my Lunetta-Lab. The idea was to feed the output of an oscillator into a shift register and then play the bit pattern back as a waveform.
This circuit isn't completely done, and I haven't analyzed it with my scope yet, but it sure sounds interesting as it is now, so I decided to post what I have so far.
There is some interesting rhythmic pattern coming from the interference of the shift and load frequencies. The tempo of the pattern and the overall pitch can be varied. When the chopper is enabled and the oscillator tuned to generate an interference with the overall sound becomes even more interesting.
The recording is just a few minutes of knob twiddling. Let's see how this circuit evolves.

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synaesthesia · Posted: Tue Sep 02, 2014 2:25 pm Post subject:

Here is an updated schematic and some explanations. The new circuit sounds exactly the same as the first, but does not produce the occasional pauses when all bits from the shift register happen to be identical. You can hear that in the recording a few times. The additional inverter makes sure there is at least one 0 and one 1 in the bit pattern.

The bit pattern itself is generated by shifting the output of another oscillator into the shift register. The frequency of that oscillator must not be any multiple of the shift register clock, so that the interference will produce inputs that make the bit pattern appear almost random. So I simply used the pitch oscillator as an input.

The pulsing rhythm comes from different frequencies that are generated by the bit patterns. The more level switches (from 0 to 1 or vice versa) there are, the higher the frequency that is generated. The lowest frequency is generated by 01111111,00000001,01111111, or 10000000. The highest frequency is four times (3 octaves) higher and generated by 01010101 or 10101010. So with 8 bits there can be four base frequencies, each an octave apart.

I would be happy to see how this principle could be further evolved. Please share your modifications.

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