My first little gem. It runs on one 9v and is in a cheap treasure chest that I bought for $2 at a dollar store. The 1/8" jack isn't a headphone jack, but an external speaker jack for my pot cab.
Here is my little gem clipper. I can hook it onto my pocket and walk around playing guitar in my apartment. No volume control, I just use the guitar's volume...and leave it all the way up anyway. The switch on it goes from clean to OD. It runs on 3xAA.
The schematic is available at runoffgroove.com and in the schematics section of the forum.