Q About Switching Onboard Preamp

[Paul Marossy]

I designed the PCB for the onboard electronics for my "project guitar" last weekend. Got the PCB etched last night and populated it this morning (more like the middle of the night since I get up at 4:00AM nowadays - got young children). It measures about 3/4"x2" and has Tillman's little FET preamp and Ansil's feedback thinga-ma-jig on it, too. I am going to have it so that I can switch either one on or off.

Which brings up a couple of questions:

1. I can just break the input to either circuit with a switch, but do I need to do anything else? I am concerned that I will get a popping noise when I flip the switch(es).

2. On the feedback thing Ansil designed, I assume that it only works on the pickup that it is attached to and only if it's active, correct?

Any second opinions?

[lovekraft]

AFAIK, any popping would be caused by a DC differential between the switched circuits, so simply having pulldown resistors in place should eliminate the problem.

[Paul Marossy]

Ahh, yes. The good old pulldown resistor thing. Why didn't I think it that?! I guess it's not a stombox, that's why!

Thanks. While I'm at at, I was thinking about that LM386 based feedback thing that Ansil came up with. I think that will need to have the circuit input grounded when the circuit is not in use, because I have a hunch it can sit there and oscillate with no input and somehow find its way into the signal path. I had a similar problem with my first Shaka Tube build...