Here’s a unique circuit for guitar effects builders. It uses readily available SIP sockets to allow easy transistor swapping. Experiment with different values for a personalized sound – and change it up on a whim. You can also recreate a bunch of popular pre-existing fuzz distortions with it:

Some of the fuzzes you can make after building this layout are the Basic Fuzz Face (with R.G. Keen Mods, Roger Mayer Mods, Fuller Mods), the Vox Tone Bender 5/67, runoffgroove.com’s Sili-Faces, fuzzcentral.com’s Axis Face Germanium and Silicon, Joe Gagan’s Easy Face, Aron Nelson’s Hornet, the Gus Fuzz Face, Tim Escobedo’s Many Faces, the Boutique Fuzz, and the Miss Piggy.

Guassmarkov’s site has some great tutorials on using op-amps and other basic electronic parts. There’s a boat-load of schematics, PCB images, and Eagle CAD files on there as well.

Fuzzy logic effects pedal –Link

Walkman guitar distortion pedal –Link