This is an adaptation of an effect called Push Me Pull You from Tim Escobedo. The name says it all, two transitors operating in Push-Pull. The sound is really nasty! If you want to lower your sustain and get some octave, this one is for you! I guess it would be great for organ. You can have a look on his genius designs over at Circuit Snippets.

Push Me Pull You effect redrawn in EAGLE software

The PCB is single sided, easier to make and sufficient for this application.

Push Me Pull You PCB

The source .brd and .sch files along with a .pdf export are available at: http://www.sendspace.com/file/fnsh03

Little sound preview from the original
http://www.jiggawoo.eclipse.co.uk/guitarhq/Circuitsnippets/pmpu.mp3