The Fritz; tremelo fuzz

The Fritz is a tremelo distortion making use of the "swing VCA" developed by Roland for there drum machines. I discovered this VCA in Moritz Klein's excellent drum synthesizer videos. As far as I'm aware no other guitar effect has used this circuit (for obvious reasons I suppose). It is not a combo pedal, the fuzz is an intrinsic part of the tremelo circuit. It's just that dirty. The name comes from a conversation I had while breadboarding. My dad walked in and I said "I haven't been able to work on it since my oscilloscope is on the fritz". Coincidentally "Fritz" was also the nickname of my grandfather. All together the name just fit the sound perfectly.

Controls:

The Fritz has 4 controls:

• Rate: adjusts the speed of the tremelo. Varies from a slow throb up to a quick studder. Max out the knob to enter ring mod sounds that I personally love.
• Tone: adjusts a high end roll off. The distortion can be a bit fizzly at times and this control helps tame that.
• Volume: self-explanatory. Has enough gain to push an overdrive or amp after.
• High-end switch: Toggles a treble boost in the tremelo. High-end frequencies are partially exempt from the tremelo leading to a subtle sizzle in the stuttering.

Mods:

I've done a bit of fiddling with this circuit while I was making it. Here are some of those ideas along with ones I've never done. Try some out!

• Capacitor C3 is the primary component for the tone. A smaller value will create less of a filter and a larger value will be a stronger filter.
• Capacitor C8 and potentiometer RV3 determine the frequencies of the rate knob. A smaller cap with the same pot will increase the baseline rate.
• The ratio between R14 and R13 determines both the possible oscillator frequencies and the oscillator voltage swing. The math behind it is a bit dense for this list but look into op-amp schmitt triggers to learn more.