This is my second circuit.
The basics:
Two 4558 dual op amps. One as the main oscillator, one as an LFO to make the tremolo effect.
One 386 to amplify it to the speaker. 386s honestly suck, hence the motorboating. It doesn't do that when ran through a line out.
The main tuning resistor for the primary oscillator was made by attaching a cable to a stylus on one end and pieces of film to the other.
The main tuning capacitor for the primary oscillator is actually six capacitors on a rotary switch, pulled from a Seymour Duncan Tweak Fuzz Pedal.
If you're interested in me making you something like this, let me know, and we'll work something out.
