Not an auto wah in a normal sense, more like an inductorless wah circuit driven by an LFO.
This must be one of the earliest modulation pedals and IMO it is a hidden gem. Lots of murky psychedelic madness can be found in this circuit, especially with a dirt box upfront.
Rate and Depth controls is self explanatory but the Tone control really widens the ranges of tones. Clockwise you'll get normal wah wah sweeps, roll it back and you can dial in vowel and yuo-yuo sweeps.
With the Depth control CCW, the LFO is disengaged and the unit acts as a eq / filter circuit.
Layout has some mods; power supply mod since original units was positive ground, CBE pinout for the transistors, power filer cap and protection diiode. As for the transistors, most low gain NPN silicons should work, I ended up with PN2222s in the 150Hfe ballpark.
This is soon to be boxed but need to figure out how to add a rate LED first...
*Edit* Rate LED added with help from Radu. Thanks!
Schematic is avaiable HERE
