The series connection of the 100uF electrolytic capacitor and the 1N4001 diode makes no sense. When the voltage is applied to the circuit, the capacitor is charged up to this voltage and then it has no more purpose, because no current can be taken from it by the diode in reverse direction and the s...

bmxguitarsbmx wrote: ↑08 Jun 2023, 23:51 MPSA18 bias resistor (510k) should go to some positive voltage. Likely connected to Vr.

Good call - you're right. Updated below.

The 8r2 resistor needs to be connected to the junction of the 1N4001 and the 100uf capacitor surely ? You'd think. Image below shows trace/node at 9V/8R2/diode. I did however mess up the position of the other diode, which is after the series resistor. Updated schematic below. ETA: Argh, it's 82R, n...

The biasing arrangement for U2.2 looks a little odd (blue oval in the center), there's DC continuity from U2.1 which will serve to bias U2.2. Could there be a series DC blocking capacitor missing after U2.1, maybe before or after the 1K? Good spot, I've taken another look, but pin 1 connects direct...

I kinda wish I'd tried something easier for my first trace. Does anything look very wrong here? This looks like a TS (with some mods) with a switch that adds in extra gain on the op amp plus a JFET boost on the back. There's also a separate JFET boost stage on an external footswitch - I've added tha...