Circuits in series - pulldown resistor placement.

[gmr1]

I have a board where I put an effect circuit, tone control, and gain recovery stage all on the same board in series. Originally the effect part had a pulldown resistor on the output to kill switch pops. Now that I have these 3 parts in series, should I move this resistor to the end of the three parts (the last gain stage)? It works fine as is (no pops), but wonder if makes sense in future builds to move the PD resistor. I'm slowly learning that even if it works, it may not be the "right" way to do it...

[R.G.]

A pulldown resistor only has meaning if there is one end of a capacitor which will be switched in a way so it is open circuit. If both ends of the cap are always connected, pulldowns are not in general needed.

A pulldown just fixes the voltage on the "open" end of a cap so that it does not leak itself down through the surrounding air, PCB surface contamination, and its own insulation resistance while it's held open by the switch.

[gmr1]

Got it. So seeing that it's now the cap is not the end of the circuit and is connected on both ends, the pulldown resistors that was necessary originally likely can be omitted. My newly combined circuit does finish with a capacitor, so It might be a good idea to have a pulldown res. at the end of the circuit? The cap closest to input always has both ends connected, so that end should be fine.

Thanks for the explanation! It makes perfect sense to me now as to when a PD res. may or not be needed.

A pulldown resistor only has meaning if there is one end of a capacitor which will be switched in a way so it is open circuit. If both ends of the cap are always connected, pulldowns are not in general needed.

A pulldown just fixes the voltage on the "open" end of a cap so that it does not leak itself down through the surrounding air, PCB surface contamination, and its own insulation resistance while it's held open by the switch.