swapping out trim pots for regular pots

Started by Belt, March 17, 2008, 12:16:01 PM

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Belt

Can this be done in all instances?

Thanks

Don
All for Him

petemoore

  A '100k linear' does = '100k linear' in either package...[+ or _ tolerance]
  IME you won't find 100k audio in trimpot package though.
Convention creates following, following creates convention.

Mark Hammer

Answer to your question is yes and no.  While not always true, it often happens that only a portion of the range of a trimpot is really of any use, and the rest is either useless or else buggers things up.  For example, the trimpot in the DrQ/Quack and the Bass Balls adjusts the filter range.  It is useful over maybe 40% of its full rotation, and the rest is useless and actually renders the filter non-sweeping.  Similarly, many phasers have a resonance trimpot to set the maximum possible resonance before oscillation breaks out.  Again, the trimpot value is intended to both overshoot and undershoot the ideal setting.

Now, you could simply replace a trimpot with an equivalent value chasdsis-mount pot and tweak away, as I have happily done on many occasions.  Alternatively, you could identify the range of the trimpot that gives you something you can use, find the nearest common value equivalent in chassis-mount pot, and make up the difference with fixed resistors on each outside lug.  So, if the trimpot is 10k but you really only get something useful out of the middle 4k, you could either use a 5k pot and stick a 2k2 resistor on one side and a 2k7 on the other, and take your chances that the outside positions will give you something undesirable.  Or, you could content yourself with less than the full range of possible adjustments, by using a 2k5 trimpot and a 3k6 fixed resistor on each end (or maybe a 3k3 on one end and a 3k9 on the other if the sweet spot needs to be bumped over).

You get the general idea.  It's to snag the benefits without the costs.

petemoore

  Forgot..
  See GEO, 'The Secret Life of Pots'
Convention creates following, following creates convention.