From: "Frank Bemelman"
References: <firstname.lastname@example.org> <email@example.com>
Subject: Re: steppermotor as encoder -> presto, moterized pot.
Date: Sun, 6 Oct 2002 02:05:11 +0200
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Organization: EuroNet Internet
NNTP-Posting-Date: 06 Oct 2002 00:06:31 GMT
"Richard Steven Walz" schreef in bericht
> In article <firstname.lastname@example.org>,
> Frank Bemelman wrote:
> >Just had an idea, and I'm not planning to actually build
> >something, but liked to share the idea - if it is an idea.
> >What we want is a moterized pot for a homemade amplifier,
> >so that it can be controlled both manually and by remotecontrol.
> >Since we lack mechanical skills (not me of course) we want it to
> >be mechanically simple. For cosmetic reasons we want the volume
> >knob to turn as well, when using the remote.
> >Okay. We use a size 17 steppermotor from an old 5.25 floppy
> >drive. Some circuit to convert to logic levels, a PIC
> >to decode etc. Now we have a signal to control a digital
> >volume control. Easy.
> >PIC also controls 4 outputs (steppers from floppydrives are
> >often unipolar) if the remote wants to move the 'pot'. In this
> >case, the software ignores the inputs, and simply increases
> >or decreases the control of the *digital* pot, and stepping
> >the motor with knob accordingly.
> >Frank Bemelman
> Silly, use a digital pot! An up-dn counter with a clock which dials in a
> resistive network tap to set a value, which goes to an op-amp in the
> feedback loop.
Nah, we want the turnable knob too. A quick quarter clockwise turn
increases the volume in a predictable way. It's okay to have up/dn
buttons on the remote, although even a turnable knob would be
> If you just really want the knob to move mysteriously, use a stepper.
> Okay for a tuner or such, but for a pot that's silly!
The more expensive amplifiers use motorized pots, to provide that
handy knob you can turn *and* make it controllable by a remote.
Tough to build for the average hobbiest, unless he can get his
hands on a true moterized pot. This stepper-thing could be an
Perhaps it was a silly idea ;)
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