Re: Source Sealed Potentiometers?

John Mianowski wrote:

.... snip ...

What I need to do is rotate what amounts to a
lazy-susan/turntable/camera mount (pan only). I need to rotate up to
360 degrees, but not continuous. The device sits on a bearing so there
is no center shaft that I might couple to. OD is 3". My plan is to
attach a gear (I've got that part worked out OK) to be driven by an
electric motor. What I need is some sort of position feedback. The
gear I've chosen for the turntable has 156 teeth with a pitch diamter
of 3.25". I figure that with a mating 32-tooth gear, I can attach a
5-turn pot. (ratio = 4.875:1, leaving a little travel at either end).
What I DON'T have, besides a shaft to couple onto directly, is space
for another 3.25"-dia. gear to keep the ratio of turntable to position
sensor at 1:1 or below, & I'd like to avoid using a multi-stage
reduction gear if I don't absolutely have to.

I also have to be able to survive immersion in fresh water for up to 30
minutes.

What sort of positional resolution (in degrees, or even in gear
teeth count) do you require? Something like a pair of leds for
tooth resolution, and a reset mechanism via a microswitch could
provide the position. The pair of leds can detect rotation
direction, and the whole schmeer should be immune to over-rotation,
unlike a pot. Counting the 156 teeth should give you roughly 2
degrees of positional resolution.

Your only worry would be the effect on the light path of the
immersion, which should not be excessive in fresh water.

--
Some informative links:
<news:news.announce.newusers
<http://www.geocities.com/nnqweb/>
<http://www.catb.org/~esr/faqs/smart-questions.html>
<http://www.caliburn.nl/topposting.html>
<http://www.netmeister.org/news/learn2quote.html>
<http://cfaj.freeshell.org/google/>


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Relevant Pages

  • Re: Source Sealed Potentiometers?
    ... I need to rotate up to ... gear I've chosen for the turntable has 156 teeth with a pitch diamter ... A prior prototype used a pair of reflective optical sensors, ...
    (comp.arch.embedded)
  • Re: Source Sealed Potentiometers?
    ... I need to rotate up to ... gear I've chosen for the turntable has 156 teeth with a pitch diamter ... A prior prototype used a pair of reflective optical sensors, ...
    (comp.arch.embedded)
  • Re: Source Sealed Potentiometers?
    ... gear I've chosen for the turntable has 156 teeth with a pitch diamter ... What sort of positional resolution (in degrees, ... A prior prototype used a pair of reflective optical sensors, ...
    (comp.arch.embedded)
  • Re: Source Sealed Potentiometers?
    ... gear I've chosen for the turntable has 156 teeth with a pitch diamter ... What sort of positional resolution (in degrees, ... A prior prototype used a pair of reflective optical sensors, ...
    (comp.arch.embedded)
  • Re: Source Sealed Potentiometers?
    ... gear I've chosen for the turntable has 156 teeth with a pitch diamter ... Counting the 156 teeth should give you roughly 2 ... A prior prototype used a pair of reflective optical sensors, ...
    (comp.arch.embedded)