Here’s another interesting snippet from the Stompbox Cookbook. I was not able to get this to work. Who knows what went on in the mind of Mr. Boscorelli?
Looks like the guitar signal is meant to modulate the frequency of the 7555 via pin 5. The 7555 then drives the 567, a phase lock loop, which tries to lock on to the signal.
The left half of this scan got cut off. If anyone is interested I’ll post the rest. I think there is just a volume pot.
Here’s a link to some info on the 567:http://mysite.du.edu/~etuttle/electron/elect12.htm