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Subject: Re: steppermotor as encoder -> presto, moterized pot.
References: <email@example.com> <firstname.lastname@example.org> <email@example.com>
Organization: The Armory
X-Newsreader: trn 4.0-test69 (20 September 1998)
From: firstname.lastname@example.org (Richard Steven Walz)
Date: 06 Oct 2002 22:43:52 GMT
In article <email@example.com>,
>"Richard Steven Walz" wrote in message
>> 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.
>> 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!
>> -Steve Walz email@example.com ftp://ftp.armory.com/pub/user/rstevew
>> Electronics Site!! 1000's of Files and Dirs!! With Schematics Galore!!
>> http://www.armory.com/~rstevew or http://www.armory.com/~rstevew/Public
>I think what the OP was saying is that he proposes using the stepper
>a) as an encoder when the volume control is operated manually. From there it
>goes via a PIC to a digital volume control. Far from silly.
>b) as a motor to cosmetically move the knob when operated from the remote.
>Sounds like a neat idea to me. Elegant even. Maybe a non-silly person would
>like to comment on the feasibility of what the OP proposed.
Okay, problem. When you turn a stepper VERY slowly, nothing comes out of
it. You STILL need either a motorized pot or encoder or some sort on the
stepper shaft. Now a geared stepper would probably work!
-Steve Walz firstname.lastname@example.org ftp://ftp.armory.com/pub/user/rstevew
Electronics Site!! 1000's of Files and Dirs!! With Schematics Galore!!
http://www.armory.com/~rstevew or http://www.armory.com/~rstevew/Public
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