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I Don't See The Point

Discussion in 'Electronic Basics' started by James Stroker, Nov 16, 2003.

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  1. I thought the purpose of dual potentiometers was to change the
    value of both pots by the same amount at the same time. But
    every duo-pot that I've gotten is off between the pots;
    sometimes a little, sometimes a lot. But so far I've never found
    a dual pot where the values tracked each other. Why do they make
    them if they don't track each other?
  2. Peter Meyer

    Peter Meyer Guest


    Well, I think it is possible to get the two to track to any error one needs.
    but this will be expensive...
    I would suggest you use two small trim pots in series - but most of the time
    it is not really necessary : for sound applications the tracking error in
    "normal price" duals is most of the time not audible.
  3. JeffM

    JeffM Guest

    I've never found a dual pot where the values tracked each other

    The response in each is proportional.
    Expecting exact matching in pots would
    ignore the differences in the circuits in which they are connected,
    which have their own differences.
  4. For audiophile work, one can buy multiple ganged 256 position rotary
    switches with precision resistor networks built in. These track very well,
    and indeed cost many $100's

  5. Ahh, but that's he point. Let's say I wanted to build a filter
    where the frequency is dependent upon two resistor values. To
    change the frequency response is to change both values equally.

    The usual formulas for determining the frequency are never
    accurate but are ballpark figures. If I had a dual pot that
    changed by the same amount on each pot, I could easily use that
    pot to check out the frequency response of that filter without
    having to use two separate pots to be adjusted to the same

    I can see a lot of real-world reasons for having dual pots with
    the same values tracking each other. But there doesn't seem to
    be much of a point to me anyway, for having two different pots
    that aren't ever going to be the same. And for that matter, I
    would never know without doing measuring, what each value is at
    any given time between the two extremes of "zero" and whatever
    upper limit.

    JeffM wrote in message ...
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