[no subject]

I've got a gob of electronics mounted on a spinning rotor, which I
need to control via a PC parallel port. (Some small green gnomes awoke
me in the night and told me to do this; I don't ask questions.) The
ON-topic bit is that I'm using the parapin library
&lt;<a  rel="nofollow" href="http://parapin.sourceforge.net";>http://parapin.sourceforge.net</a>&gt; under Linux to write the driver;
parapin is a very nice hunk of software.

The OFF-topic bit is that interfacing the parallel port to the
spinning gizmo presents a mechanical engineering problem that I'm
having trouble solving effectively, and I don't know where to begin
looking for the &quot;right&quot; answer. The angular velocity is on the order
of 300 RPMs. At the moment, for proof-of-concept, I've got the I/O
pins on the spinning thingy connected to some 22-gauge wires that just
crudely wrap around the motor shaft, and another jury-rigged set of
stationary brushes (also made from 22-gauge wire) that make annoyingly
intermittent contact with those loops, and to which the parallel port
is connected. It kinda works, but it's not very reliable, and the
crappy brush mechanism places a noticable mechanical load on the motor
(RPMs decline significantly when the brushes are in contact with the
loops, even though the motor power supply is completely isolated from
the power source driving the electronics).

I bet there's some standard solution to this kind of problem that I'm
just not aware of, which I could adapt to my needs. Any pointers
thereto would be greatly appreciated.

Thanks,

-- Joe Knapka

-- 
&quot;Meet the new boss / Same as the old boss...&quot; -- The Who
... Oh well, at least there's 2008.
--
pub  1024D/BA496D2B 2004-05-14 Joseph A Knapka
     Key fingerprint = 3BA2 FE72 3CBA D4C2 21E4  C9B4 3230 94D7 BA49 6D2B
If you really want to get my attention, send mail to
jknapka .at. kneuro .dot. net.


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<li><strong><a name="00085" href="msg00085.html">[ale] [Almost totally OT] Rotating hardware interface.</a></strong>
<ul><li><em>From:</em> keith.watson at gtri.gatech.edu (Keith R. Watson)</li></ul></li>
<li><strong><a name="00143" href="msg00143.html">[ale] [Almost totally OT] Rotating hardware interface.</a></strong>
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