basic potentiometer advice

[jamiewoody]

if you wired a potentiometer and you make 3/4 of the twist of the knob, and it does not effect the sound, should you go with a smaller value? (if the pot was 100k, should you move down to 10k instead?

or should you just wire a trimmer with the variable pin? (if it is already wired up)?

[Gordonjcp]

It depends ;-)

If you're replacing a fixed resistor with a pot, then work out a suitable minimum value and use that as a series resistor.  For instance, if you've got a 1k resistor, a 10k pot in series with a 100 ohm resistor will give you control over two decades - you can have a tenth as much, or ten times as much resistance.  It won't be very linear, though.

[jamiewoody]

i wasn't talking about a fixed resistor.

let's say i wired a potentiometer (variable resistor). give it a 1/4 turn, and it effects the sound. turn it the other 3/4 turn, and it effects the sound no longer.

so, should i replace the pot with a pot of smaller resistance or more resistance? (as a rule, i know there are always exceptions to a rule.

[noiseybeast]

It depends ;-)

If you're replacing a fixed resistor with a pot, then work out a suitable minimum value and use that as a series resistor.  For instance, if you've got a 1k resistor, a 10k pot in series with a 100 ohm resistor will give you control over two decades - you can have a tenth as much, or ten times as much resistance.  It won't be very linear, though.

What won't be linear?

[Gordonjcp]

Well, if you have a 10k fixed resistor in an RC circuit - say like a decay control - you could get 1/10th the time constant by using a 1k resistor, or ten times the time by using a 100k resistor.  Except, you won't, exactly, because other parts of the circuit will interact.

Furthermore, if you wire a 100k pot in series with a 1k resistor, then you'll get a variable decay that can go from 1/10th normal with the pot at minimum (1k only) to ten times normal (1k fixed, in series with 100k pot - tolerance will place it around 90-110k because they're fairly loose).  However, the "normal" 10k setting will be about 1/10th of the rotation of the pot - think about it.  So, the useful range will be all up one end.  Of course, this is why we use logarithmic pots, but even so you wouldn't have a particularly linear response - you wouldn't be able to mark of even divisions of time.

If you're not too bothered about precision timing, you might not care.