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From: firstname.lastname@example.org (Tom Bruhns)
Subject: Re: A simple angular positioning solution?
Date: 29 Oct 2002 15:24:25 -0800
NNTP-Posting-Date: 29 Oct 2002 23:24:26 GMT
A couple thoughts, assuming you gotta use some existing mechanical
dial arrangement and can't just use a rotary switch:
--Use reflective emitter-sensors at one position to sense reflective
areas applied to the back of the dial.
--Embed or attach a magnet to the dial, and put four sensors around
under the dial to pick up the current dial position. Encode them
electronically if you wish. Or...if magnets are cheap, use two
sensors and a multitude of magnets.
For any scheme, you may want to consider a way to know that the dial
is at a detent, and not in between.
If you can arrange the dial as you wish, you might consider a shaft
behind the dial with cams which actuate mechanical switches. Beware
of reliability issues with mechanically-activated switch contacts.
email@example.com (WHF) wrote in message news:...
> Hi all,
> I was wondering if anybody out there had come up with a solution to
> problem similar to this or even whether they had ideas on how this
> might be done?
> I am designing something that has a plastic mechanical dial on it,
> which can click into 1 of 4 locations. Each of these locations will
> signify a mode of operation for the device. I must get the processor
> to recognise what position the dial is in, to determine what mode has
> been selected.
> I have experimented with hall effect proximity sensors, and having a
> different 2 bit binary number on each segment of the dial, but both of
> these require having some electronics on the dial which is not the
> ideal situation.
> Another idea I had was to have holes and blanks in each segment
> representing binary 1's and 0's. This would require having some
> optical transmitting and sensing circuitry on either side of the dial
> to determine which position it is in.
> Anyway All ideas would be appreciated.
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