Steggo's Take on the Harmonic Percolator!

One of the first pedals I built was AionFX's Particle - a modified version of the vintage Interfax Harmonic Percolator. It was a really neat Fuzz pedal, and AionFX provided recipes for both the normal unit and a version modified by Steve Albini. When I first started to learn to lay out my own boards, I wanted to get as much practice as possible. So I went ahead and laid out my own version of this circuit.

I neglected to get a good shot of the PCB before I dropped it in the enclosure, so I went ahead and enlarged the board from the full interior shot of the enclosure. As you can see, the circuit itself is very simple. Only five resistors and eight capacitors. I'm using my normal mix of 1% metal film resistors and film capacitors for the most part. There are a couple of MLCC capacitors for the lower values. The electrolytic capacitors are all Nichicon.

Past that is where things can get a bit weird or exotic for this build as it is a older pedal. I went ahead and added the clipping switch from the AionFX version which allows you to choose between the normal germanium clipping diodes, silicon clipping diodes, or no clipping diodes. The silicon diodes are 1N914, so they're extremely common. The original pedal used 1N695 germanium diodes, but just about any germanium diode should work. I just used 1N34A diodes for my test build.  

There are two transistors which can be hard to fine if you try and match the original as well. The original used a 2N3565 transistor, but there are others which can be used here. I had one, so I went ahead and used it for my test build. For the germanium side, the original used a 2N404A. These can still be found, but for my test I had a lot of germanium transistors a friend in Ukraine sent me, so I used a P308 that matched the electrical properties of the original.

The rest of the build was straightforward. I'm using my normal 3PDT daughter board that has the LED CLR and LED on it. I decided not to enable the brightness control. The audio jacks are Switchcraft and I'm using a Lumberg DC jack, but no battery. As normal, the jack connections are all insulated with heat shrink tubing and I'm using aviation grade wire from Tube Depot. 

For the enclosure, I ended up going with the Pelorosaurus - largely because it began with "p" and I could use fairly stylized sauropod art with it. According to Wikipedia:

"Pelorosaurus (meaning "monstrous lizard") is a genus of titanosauriform sauropod dinosaur. Remains referred to Pelorosaurus date from the Early Cretaceous period, about 140-125 million years ago, and have been found in England and Portugal. Thomas Holtz estimated its length at 24 meters (79 feet).

"The name Pelorosaurus was one of the first to be given to any sauropod. Many species have been assigned to the genus historically, but most are currently considered to belong to other genera. Problematically, the first named species of Pelorosaurus, P. conybeari, is a junior synonym of Cetiosaurus brevis."

In terms of the sound I've always preferred the "standard" version of the percolator to the Albini mod, though I may be in the minority there. This build sounds pretty much like the original AionFX version I built a few years back - so I'm calling the board a success! I've got some ideas for modifications to the percolator design I want to try, so stay tuned!