ASYNC RSG RPM

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "S & J Young by way of Terry Fritz <twftesla-at-qwest-dot-net>" <youngs-at-konnections-dot-net>

Hi all,

Just wondering if some of you have good ideas for monitoring async RPM of a
RSG while the TC is operating.  Specifically, a direct readout, not syncing
a strobe light.

The electrical environment around a RSG is truly horrible, and I suspect
most electronics will fail or not operate correctly.  Currently, I just
monitor the AC voltage to the drive motor and compare it to a calibration
chart of RPM measurements made with no HV to the TC.  OK, but is there a
better, more accurate way?

One idea is to couple a bicycle generator to the RSG shaft.  The bike
generator is a low impedance AC generator which could drive a frequency
meter.  But the connecting wires would be a good antenna, and I fear the
freq meter would get zapped.

Another idea is to sense the current pulses in a gap lead, something like a
clamp-on ammeter.  But again, I fear the common mode pickup of the
connecting cable will destroy the readout electronics.

Focus the light from a gap via lens to a distant photo pickup?  Junkyard
speedometer?  Use some sort of battery powered sensor (e.g. Hall effect) to
drive a fiber optic connection to the freq meter?

Any ideas out there?

Thanks in advance,
--Steve