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Re: one potentiometer dividing multiple signals

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On 3/16/2026 8:21 AM, Christopher Howard wrote:
> In my analog computer setup, a very common thing is to use
> potentiometers as coefficients, i.e., as voltage dividers that attenuate
> an input signal. But something wasteful about this is that sometimes
> multiple different signals have to be divided by the same coefficient —
> for example, dividing various forces by the mass of the object. So, I
> have to use multiple potentiometers for that, and I have to keep them
> set to the same value.

You are using the pots as resistive dividers (?)  The ratio of the two
"sides" of the wiper effectively determines the divisor.  I.e., if
60% of the total resistance is on one side of the tap, then you are
dividing by 100%/60% (or, 100%/40%, depending on your point of
reference).

[There are other ways of configuring the pot, too]

To have multiple pots act in unison, you need a multiple-gang pot:
<https://nolelc.com/wp-content/uploads/2026/01/multi-gang-rotary-potentiometer.webp>
Here, both pots are operated by the same rotary shaft.

You can typically see such devices in use in a legacy "stereo"
where one pot controls the volume of the left channel while
the other (on the same shaft) controls the volume of the
right channel.

The problem with this approach is that the two don't always track
perfectly.  E.g., one may yield 60% while the other reflects 59%.
Also, the tapers may have slight differences.  So, the "60" may
become "61" as the pot is turned while the "59" may become "59.5"
despite the shaft having turned the same amount in each.

It's also more expensive and there are limits to just how many
pots you can stack on a shaft.

> So, I was wondering what would be the simplest analog approach to get
> around this problem, without having to use expensive
> multiplier/dividers. Maybe just have one potentiometer connected to a
> bunch of cheap transistors?

In that approach, you are trying to replicate a *voltage* for distribution
to multiple consumers.  You are only "dividing" the ONE signal that is
presented to the pot ("divider"); your further attempts ("transistors")
are just *replicating* it (and buffering each).

Look at the "math" you are attempting to perform.  See if you can
exploit associative and commutative properties to rearrange the
"equation" to reduce the number of "divisions":

x/K + y/K would require two divisions by K.  But, (x + y)/K
requires only one.

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one potentiometer dividing multiple signals Christopher Howard <christopher@librehacker.com> - 2026-03-16 07:21 -0800
  Re: one potentiometer dividing multiple signals Martin Brown <'''newspam'''@nonad.co.uk> - 2026-03-16 15:45 +0000
  Re: one potentiometer dividing multiple signals "Edward Rawde" <invalid@invalid.invalid> - 2026-03-16 11:50 -0400
  Re: one potentiometer dividing multiple signals john larkin <jl@glen--canyon.com> - 2026-03-16 09:42 -0700
  Re: one potentiometer dividing multiple signals Don Y <blockedofcourse@foo.invalid> - 2026-03-16 09:54 -0700
  Re: one potentiometer dividing multiple signals liz@poppyrecords.invalid.invalid (Liz Tuddenham) - 2026-03-16 20:03 +0000
    Re: one potentiometer dividing multiple signals liz@poppyrecords.invalid.invalid (Liz Tuddenham) - 2026-03-19 10:01 +0000
  Re: one potentiometer dividing multiple signals antispam@fricas.org (Waldek Hebisch) - 2026-03-17 21:28 +0000
    Re: one potentiometer dividing multiple signals Christopher Howard <christopher@librehacker.com> - 2026-03-18 08:25 -0800
      Re: one potentiometer dividing multiple signals John R Walliker <jrwalliker@gmail.com> - 2026-03-18 16:34 +0000
      Re: one potentiometer dividing multiple signals Martin Brown <'''newspam'''@nonad.co.uk> - 2026-03-19 12:42 +0000
        Re: one potentiometer dividing multiple signals Christopher Howard <christopher@librehacker.com> - 2026-03-19 11:51 -0800
          Re: one potentiometer dividing multiple signals john larkin <jl@glen--canyon.com> - 2026-03-19 13:16 -0700
          Re: one potentiometer dividing multiple signals liz@poppyrecords.invalid.invalid (Liz Tuddenham) - 2026-03-19 22:18 +0000
          Re: one potentiometer dividing multiple signals Jasen Betts <usenet@revmaps.no-ip.org> - 2026-03-20 07:29 +0000
          Re: one potentiometer dividing multiple signals liz@poppyrecords.invalid.invalid (Liz Tuddenham) - 2026-03-20 09:05 +0000
      Re: one potentiometer dividing multiple signals Jasen Betts <usenet@revmaps.no-ip.org> - 2026-03-20 07:25 +0000
        Re: one potentiometer dividing multiple signals liz@poppyrecords.invalid.invalid (Liz Tuddenham) - 2026-03-20 09:05 +0000
  Re: one potentiometer dividing multiple signals someone <cffbf4deb9142bce48974efc0e64dede@example.com> - 2026-03-17 22:30 +0000
  Re: one potentiometer dividing multiple signals liz@poppyrecords.invalid.invalid (Liz Tuddenham) - 2026-03-19 18:44 +0000
  Re: one potentiometer dividing multiple signals Jasen Betts <usenet@revmaps.no-ip.org> - 2026-03-20 07:12 +0000
  Re: one potentiometer dividing multiple signals john larkin <jl@glen--canyon.com> - 2026-03-20 09:08 -0700
    Re: one potentiometer dividing multiple signals Ross Finlayson <ross.a.finlayson@gmail.com> - 2026-03-20 11:52 -0700
    Re: one potentiometer dividing multiple signals Christopher Howard <christopher@librehacker.com> - 2026-03-23 09:09 -0800
      Re: one potentiometer dividing multiple signals piglet <erichpwagner@hotmail.com> - 2026-03-24 08:48 +0000

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