Re: ASYNC RSG RPM

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

Original poster: "bob golding by way of Terry Fritz <twftesla-at-qwest-dot-net>" <yubba-at-clara-dot-net>

Hi Steve,
    I use an old centrifuge motor with a encoder on the end of the shaft.
This is connected to a diode bridge and a meter calibrated in RPM via 10 ft
of screened cable.  My coil produces 8 foot sparks . I haven't had any
problems with this system yet... I would try the bike dynamo idea, should
work  if you  can calibrate it. I find that the safety gap across the rotary
works very well as a speed indicator. There is a direct linear relationship
between voltage and air gap so if you set the gap to the highest voltage you
want to subject your caps to, it will fire when the speed drops too low. I
find that the longest sparks are just before the gap fires. I know this
isn't very scientific but it works.

cheers
bob golding


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Monday, July 30, 2001 5:27 AM
Subject: ASYNC RSG RPM


> 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
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