Can I substitute a trimpot by a regular pot?

[Lucianorg]

Simple question: Can I substitute a trimpot by a regular pot?

I made  a doctor quack circuit which uses a 20k trimpot. Can I change it for a 20k pot. If so, would it be better a pot type A(linear) or B(log)?

Thanks.

[Mark Hammer]

I have a panel-mounted pot on mine.  Keep in mind, though, that an exact value-replacement would not be usable over its entire range.  My advice is to measure the input-to-wiper resistance of the trimpot at the point where decreasing it any further results in no change, with the sensitivity up full).  Add 10k to that, and use another fixed resistor to make up the full difference between that and 25k.

So, to illustrate, let's say you don't really hear any useful change in the filter until there is at least 4.5k of resistance between the input to the trimpot, and the trimpot wiper.  Okay let's solder a 4k7 fixed resistor to the input lug of a panel-mount pot, a 10k fixed resistor to the other outside lug, and run wires from the free ends of the added resistors to the pads on the board where the trimpot legs would have normally been soldered.

Doing that should give you a panel-mount pot, using commonly-available component values, that will provide usable change across its full rotation.  It may be less than that (e.g., only useful across 80% of its rotation), or the pot might not cover all of the potentially usable range (i.e., the pot is useful across its full rotation, but there is still just a little more adjustment possible that you can't do with that pot value), but you'll end up with a control that isn't confined to a small twitchy arc of rotation, and create the sense that the pedal has stopped working if you verge outside of that arc.

Not that adjustments to the trimpot/pot will often necessitate changes to the sensitivity control.

[Lucianorg]

That fully answered my question. Thank you.