Subject:
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Re: Rotation Contacts
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Newsgroups:
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lugnet.robotics
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Date:
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Thu, 4 Jan 2001 18:26:36 GMT
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Original-From:
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John Barnes <barnes@SAYNOTOSPAMsensors.com>
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Viewed:
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744 times
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Michael Gasperi" wrote:
>> This is a modestly easy task, if you use a telephone cord untangler.
>
>How much current do you think you can put through one of these? Also, do
>you get any contact bouncing while the thing rotates that might be read as a
>change in sensor state?
I have tried a number of different brands. They all have gold plated
contacts and
thus don't oxidize readily. If you work on them with tiny Xacto style saws
or blades
as I do, DONT let the little pieces of plastic find their way inside. That
causes
problems.
As far as contact noise is concerned, my preferred brand is not the Radio Shack
style which uses rings around a central axis made of bent wire. There is a
notch
which can cause trouble although I have never noted any symptoms. The RCX
only samples the input channel for 50uS out of 3000uS, so the chances of
getting
a signal interruption at the wrong moment is reduced. (There are three channels
sampled during a 200uS window, of which the first 50uS is settling time
followed
by a sequential scan of the three sensor inputs at 50uS each in reverse order.)
The motors have such a substantial flywheel effect that a temporary "open"
which
would be equivalent to the float state would be hard to detect.
My preferred untangler which is sold by Wegmans grocery stores here in the NE
has a small circular printed circuit board in it which has four concentric
gold plated
rings with gold plated wire wipers. These are easy to modify - you want to
cut off
the telephone style 4 way connectors and solder directly to the electric
plating
pieces. This untangler housing is transparent and the outer diameter happens to
be a nice snug fit in the inside of the turntable's inner toothing.
JB
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Message is in Reply To:
 | | Re: Rotation Contacts
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| This is a modestly easy task, if you use a telephone cord untangler. I have "modified" a number of these to make 4 wire rotating connections, typically for feeding through the large turntable. By carefully cutting the metal part, you can turn 2x4 (...) (24 years ago, 4-Jan-01, to lugnet.robotics)
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