Circuitbenders Forum
Circuitbenders Forum => Circuitbending discussion => BENDING TIPS => Topic started by: jamiewoody on September 20, 2010, 03:50:52 PM
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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)?
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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.
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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.
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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?
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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.