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From: robink@aus.hp.com (Robin Kenny)
Subject: Re: Slip Rings
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Message-ID: <1994Oct4.010134.7209@hparc0.aus.hp.com>
Date: Tue, 4 Oct 1994 01:01:34 GMT
References: <sengle-2309941703590001@port132.blkbox.com> <Cwn6Cq.MFs@world.std.com> <barrus-270994085030@centris3.merl.com>
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Further info on slip rings:
 ordinary wire brushes can be used to contact the rotating conducting ring.
The cheapest set up I have ever seen was an old (1968) video recorder
that used three brushes per connection, the theory being that there is a
one_in_eight chance of all three brushes not being in contact with the ring
at the same time. This worked very well.
If you supply DC power through these brushes then on-platform circuitry 
could FM modulate the information which could return either by another slip 
ring set, optically or by a rotary transformer coupling. 


Robin Kenny - robink@hparc0.aus.hp.com           "New ideas in status quo"
(everything in this message is PERSONAL OPINION ONLY and has no connection
with my work or my employer, the Hewlett-Packard Company Australia)
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John W. Barrus (barrus@merl.com) wrote:
: > sengle@blkbox.com (Steven W. Engle) writes:
: > 
: > >Greetings. I wish to implement a rotating scanner on my 6.270 robot. It
: > >piece of hardware I believe is called a Slip Ring - it is a device which
: > >through it are NTSC video, TTL signals, Sonar Sensor signals, B+,
: > >and ground.
: > >Steve Engle
: > >sengle@blkbox.com
: > 
: Do you have an old VCR laying around?  The rotating head of the vcr does
: The VCR head does not use sliding contacts, but instead is built like two
: halves of a transformer.  Not good for DC, but above some minimum
: frequency, the signal/power should be able to get through.  (NTSC works
: great!)  Of course the small wires limit power transfer.  A four-head VCR
: John B.
