I finally built something I wanted to do for quite a while:
Chua's circuit.
It's a chaotic oscillator, which, instead of producing something incredibly boring like a sawtooth wave or whatever, creates a monkeyfighting, honest-to-god
strange attractor. In fact, it's pretty much the opposite of a boring, well-behaved wave: it never repeats. It never does the same thing twice, which is pretty crazy if you think about it.
After doing a compact one on stripboard which turned out to be a pain in the ass as I was looking for shorts and everything, I did it again on perfboard with lots of space and laid out like the circuit diagram:
I immediately got the double scroll after turning the knob, which was a nice surprise:
About half the parts are from old junk like broken TV sets.
The sound file below is what it sounds like hooked up to a guitar amp, the high-pitched beeps at the beginning and the end are produced when the circuit is not chaotic, at the start there is
period doubling which happens when the sound becomes more complex and then it turns chaotic as I turn the potentiometer knob: