Earthquaker Bellows

[lrgaraujo]

Some three years ago, I posted a question about making a darlington pair out of two BJTs for the Bellows. Breadboarded it and it worked nice, but I've decided to wait and buy a proper MPSA13.
Fastforward to last weekend, I have finally remembered to order the MPSA13, but all of a sudden, I can't wait 3 days for the order to arrive and build the pedal using a pair of matched 2n3904 (hfe=190, if my multimeter can be trusted), and I'm happy I did, cause it sounds awesome.

Simple graphics and messy guts for you to enjoy: