[sci.electronics] Electrical interface to a spinning device needed

deanr@sco.COM (Dean Reece) (09/26/89)

I am looking for a rather unusual item, and I have hopes that some kind
netlander(s) can point me to a vendor.  I need a rotating interlock.
I have a motor spinning something that needs power and a few TTL signals.
I can make one of these using P.C.Boards and scavanged switch contacts, but
I'm sure I couldn't come close to the quality/liftime of industrial units.

The circuits to be sent are Power (+5 VDC & about 5 Amps), 4 TTL signals
(serial at about 1 megabit per second) and a sync contact that should 
generate some constant number of pulses per revolution.  Optical sync
would be ok, I just need some rough tachometer for the motor.  Fortunatly
the motor is fairly slow (about 200-500 RPM), and there will be plenty
of air flow (this will help keep the contacts cool).  Also, this is for
use in a fairly gentle environment (i.e. not automotive) so only dust will
be a problem.  Oh, if it matters, the shaft is about 1/2" diameter and
I've got a flat area to mount to as well about 4.5" in diameter, so either
a cylinder or disk could be used.  One last point of interest, I need to
keep the shaft isolated, since it may come in contact with 120VAC, so I
can't use that for a high current ground contact (damn!).

I know these things exist, but the question is, can I afford to buy one,
or can I build one that meets my needs?  Any pointers, comments, or ideas
are welcome.  Is there another solution (perhaps an optical interface for
the TTL signals ?)
 ______________________________________________________________________
| Dean Reece     Member Technical Staff |"The flames are all long gone |
| The Santa Cruz Operation 408/458-1422 | but the pain lingers on"     |
|___________deanr@sco.com_______________|___________________Pink_Floyd_|