Re: Fiber Optic V & A Meters

["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>

Thanks Jim,

The current monitor is the stickler and is the meter floating in one leg of
my 20 KV supply.  The Hall effect solution is a good idea that I will check
out.  Thanks for the suggestion.  I will have to monitor the more tame
current going into the final filter caps as there are huge current pulses
going out to the tank circuit.

I do monitor the voltage as you suggest, but I have to use two voltage
dividers and put the meter across the two bottom resistors, as my supply is
plus & minus 10 KV.  I use strings of 40 1 meg resistors in each leg.  Meter
never gets above half a volt.  I have some hefty back to back diodes to
ground across the bottom divider resistors for safety.
--Steve Young


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Saturday, August 24, 2002 11:41 PM
Subject: Re: Fiber Optic V & A Meters


> Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<jimlux-at-earthlink-dot-net>
>
> Led and phototransistor, using the inexpensive 1000 micron plastic fiber,
is
> fairly linear.. (at least better than the 5-10% FS of an analog meter).
>
> If you want fancier, use an op amp, drive two LEDs in series, put one
> photoreceiver in the feedback loop of the op amp.
>
> Other strategies are to use a Voltage to freq converter to drive the
LED...
>
> DC current probes are about $20 (based on Hall effect sensors) (from
> Honeywell, and others.. check the catalogs).. you can easily put 50kV
> insulated wire through the hole.
>
> For the voltage, you can just use a suitable divider, and put your meter
at
> ground.  A string of 30 Meg resistors won't load it much, and the
precision
> is fairly good.
>
>
> ----- Original Message -----
> From: "Tesla list" <tesla-at-pupman-dot-com>
> To: <tesla-at-pupman-dot-com>
> Sent: Saturday, August 24, 2002 10:23 PM
> Subject: Fiber Optic V & A Meters
>
>
> > Original poster: "S & J Young by way of Terry Fritz
<twftesla-at-qwest-dot-net>"
> <youngs-at-konnections-dot-net>
> >
> > 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
> >
> >
> >
> >
>
>
>