Playing with a soldering iron
Sounds like a machine. Pretty easy build using a layout from freestompboxes.org.
I haven’t looked at the freestompboxes version, but this CGS Synth module is a Lockhart wave folder. He implies it doesn’t have as much of a fifth-up effect as much as a makes-lots-of-racket effect. Been thinking about trying it out but haven’t gotten around to it yet.
Typo’d the link, apparently. Should be here: http://www.cgs.synth.net/modules/cgs52_folder.html
Really, this is a ZVex Machine clone. Look up the schematic. It’s made of a booster/pre-amp followed by a two of the Lockhart circuits.
I would agree, it sounds like “lot of racket”, with a hint of octave up.
Tim Excobedo posted a circuit years ago called the Tripple Fuzz, which is based on the Lockhart thing. I built one of these, it sounded about the same, this one is more over top wall of sound, which makes sense, since it has not one but two of the “non-selective frequency triplers”.
I have a couple of the CGS Wave Folder PCBs I got years ago, I haven’t built them yet. I suspect it could be useful in a modular synth.