Re: Source Sealed Potentiometers?


Paul E. Bennett wrote:
John Mianowski wrote:


Paul E. Bennett wrote:
John Mianowski wrote:

IP 67 is flush water, IP 68 is under water.
You want to measure an angle ?
What is the angular speed of the sensor ?

Rene
--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net

I need to be able to survive immersed in fresh water for several
minutes. I think I might be able to get away with IP67.

I need to be able to measure an angle 0-360, & can't directly couple to
the shaft/axis of rotation. I can put a gear on the object to be
measured, & due to space constraints I need to reduce at least 5:1.

Angular speed would be slow, probably no more than about 30 RPM.

Is cost an issue or are you able to look at synchro/resolvers as a means
to measure the angle. There are some around that, due to their
construction, are OK for immersion. The solution is more expensive than a
pot for measuring angle but is quite dependable.


I'd like to keep the cost down, for sure. I haven't found any synchros
or resolvers that can deal with multiple turns, & I don't have a way to
tell which turn it might be on after power-up/reset. A multi-turn pot.
would work very nicely, but all I've been able to find that are
immersable are pretty pricey (i.e. oil-filled, $US80 & up).

You stated that you could use a gear for reduction. The way resolvers are
usually used for keeping track of multiple turns of a shaft and how far the
shaft itself has gone would be to use two. However, as you have stated that
direct drive is not possible and you would be gearing anyway you could just
gear the synchro/resolver appropriately to gain the desired revolutions in
one turn of the synchro/resolver shaft. Naturally, the applicability of
this woul depnd on the accuracy and resolution you require of the
measurement.

We are all groping a little with such scant detail of the situation.Perhaps
a little more about the nature of your requirement here would help us help
you.


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.

Thanks!

JM

.

Relevant Pages

  • Re: Source Sealed Potentiometers?
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