I've done a fair bit of research about converting an old Wah to an expression pedal,
including this great post:
I'm hoping to do this for my HX Stomp, but just want to make sure I have a viable plan. I'm hoping to convert my Dunlop Crybaby to act in the same way as the new Mission Helix SP1-L6H REVISION B, which only requires a single TRS cable, rather than the Y-Cable splitter which the Revision A used. I believe I have all the parts I'll need (Dunlop 10K Wah Pot, 3PDT Switch, 10K Resistor, 1/4" STEREO jack), I'm just wondering if anyone has the know-how for how exactly I would wire it all up to make the HX Stomp happy. I believe the SP1-L6H REV. B uses a circuit board, and although I've etched a circuit board or two in the past, I'd prefer to keep this project as simple as possible without requiring a circuit board. I assume the setup would be pretty close to what Verne-Bunsen outlines for the Helix, but I don't quite understand how to wire the single TRS jack instead of the two TS jacks.