One Chip Pony — Comparator Fuzz

[Aleph Null]

This is my first attempt at PCB design. I chose a simple circuit and followed along to DigiKey's KiCad tutorials.. The One Chip Pony only does one trick—and it only uses one chip!



Clown color hydro-dip finish felt appropriate.



Maybe it looks a little silly in such a large enclosure, but I needed the extra room for the giant knob! This layout was designed specifically to accommodate the knob and switch, and also to be easy to troubleshoot.



An input gain stage feeds a comparator. Instead of amplifying the signal until it clips, the signal is compared to the bias voltage. If the input is above the threshold, the output swings to the ground rail; if below, it swings to the supply rail. It's maximum fuzz and maximum compression all the time. Picking dynamics do come through a little, but as changes in timbre, not volume. The "Gate" switch is actually changing the input gain and the input impedance. More gain means less aggressive gating. The upshot of the gate is that the pedal is dead silent when you're not playing!

Here's a demo:

I have a couple extra PCBs. If anyone is interested, DM me.

[jessenator]

Nice work! Good to see your first attempt worked out of the blue box

[NorthCoast]

Very nice!! Looks like the whole thing was really well thought out, and it sounds great.


The hydro-dip finish looks awesome, too.

[Aleph Null]

Nice work! Good to see your first attempt worked out of the blue box

Does the Blue Box use a comparator? It certainly sounds like it could be.

[jessenator]

Does the Blue Box use a comparator? It certainly sounds like it could be.

Oh I meant boards that come in JLCPCB's blue delivery box haha. But maybe you went with OshPark.

The first few pcbs I had were totally bogus or super noisy.

Glad it's working for you.

[Aleph Null]

Oh I meant boards that come in JLCPCB's blue delivery box haha. But maybe you went with OshPark.

The first few pcbs I had were totally bogus or super noisy.

These are from OSHPark. I have stuff coming from JLCPCB, but that's a story for a different thread! 

It was definitely a relief to discover there was only one small error on this first board—I swapped the ground and lamp pads that go to the bypass switch—that's easily fixed!

[TNblueshawk]

Looks great AN.

Next up a digital echo PCB design? 

[Aleph Null]

Looks great AN.

Next up a digital echo PCB design? 

Thanks! I have PCBs for my Special Sauce circuit on the way—that's built around a PT2399, so maybe that counts? I have been side-eyeing the FV-1.

[jwin615]

I love big knobs.
I love unruly fuzz.
I love this.
Great job and congrats on the first layout working out.
Should've dimed it in the demo though
I've been meaning to build one of these up. Breadboard one a few years back and loved it. This circuit has a bit more going on than the parasit layout. Was that you or inspiration from elsewhere?
Great job!

[Aleph Null]

I love big knobs.
I love unruly fuzz.
I love this.
Great job and congrats on the first layout working out.
Should've dimed it in the demo though
I've been meaning to build one of these up. Breadboard one a few years back and loved it. This circuit has a bit more going on than the parasit layout. Was that you or inspiration from elsewhere?
Great job!

I wasn't aware of Parasit circuit. I did look at Anderton's comparator fuzz, but this circuit is different from that one as well.