Comparator Fuzz

I started this experiment with the goal of creating a square wave out of a guitar signal using a comparator. The idea was to send the signal through a comparator using signal ground as the reference voltage. I drew the expected result in my notebook and then realized that I could also vary the duty cycle of the square wave by varying the reference voltage with a potentiometer.

I started with a split rail buffer to make it possible to use a single ended power supply.

The next step was adding the volume knob and reference voltage pot.

I connected the signal generator to the input and varied the reference voltage while watching the output signal on the scope.

The circuit did what it was supposed to except I noticed some crossover distortion at the output. This is common for LM324's and can be fixed with a resistor from the output to the negative supply.

I wanted to try it with a guitar to see how it sounds so I added an amplifier stage before the comparator to boost the guitar signal.

The circuit actually sounds pretty cool with a guitar. It would probably help to put an LPF before the amplifier stage if you're after a pure square wave. Since it's a comparator, the signal cuts out completely after it gets below a certain level which gives it a gated fuzz sound.