RE: Fiber Optic V & A Meters VF/FV Converters

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Original poster: "Mccauley, Daniel H by way of Terry Fritz <twftesla-at-qwest-dot-net>" <daniel.h.mccauley-at-lmco-dot-com>



There is really only one good way to do this (other than digital
transmission over fiber optic).  

You need to make up a Voltage-to-Frequency converter for the sending end and
a Frequency-to-Voltage converter
for the receiving end.  The circuits are pretty simple and a whole slew of
manufacturers make ICs for that purpose.

We've used these circuits forever in building feedback systems in high
voltage systems including radar transmitters.

For example, all you need to do is make one send/receive circuit pair say
working at 0-10VDC input.  Then just scale all your measurements to work
this range.  Very simple to do.

If you have any more questions, let me know.



I like to measure KV and mA supplied by my filtered DC supply while it is
powering my twin TC.  The supply is plus & minus 10KV, center grounded (4
MOTs, twin doublers).  I now use analog meters directly wired into the HV
and have the meters located away from the coil so I can read them without
getting streamer zaps.

I don't like the meters floating at high voltage - not safe.  I would like
them isolated by optical fiber cables.  If I use a simple LED and
phototransistor combination, or LED and photodiode and op amp, what
linearity can I expect?  I need to measure 0 to 20 KV and 0 to 200 mA.

If any of you have built fiber isolated V & A meters, please share details
and results.

Thanks,
--Steve Young