Re: [TCML] HV Panel Meters

["Phillip Slawinski" <pslawinski@xxxxxxxxx>]

So it looks like the only way to get a remotely useful reading is to use a
current clamp and a good oscilloscope.

On Thu, Jun 26, 2008 at 12:13 PM, Lau, Gary <Gary.Lau@xxxxxx> wrote:

> I tried something similar to read the current from the secondary base.
>  Trouble is, with a static gap being so chaotic, the reading varied all over
> the map.  One would need something with a much longer thermal time constant
> than a bulb filament to achieve a stable reading.
>
> Regards, Gary Lau
> MA, USA
>
> > -----Original Message-----
> > From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> > Behalf Of William Noble
> > Sent: Thursday, June 26, 2008 1:01 PM
> > To: Tesla Coil Mailing List
> > Subject: RE: [TCML] HV Panel Meters
> >
> >
> > you may wish to consider a very crude but effective way to measure
> irregular
> > currents in the analog domain - the old fashioned light bulb -
> >
> > put a bulb whose current rating is consistant with what you want to see
> (say a type
> > 47 for a small NST) in series with one lead.  Put the bulb in an
> enclosure with a
> > plastic light pipe (acrylic works well) - you can do this by just
> wrapping with tape -
> > bring the fiber to your panel - color and brightness indicate current.
>  if you want to
> > have a meter do the indicating, shine the fiber onto a
> > photocell/photoresistor/phototransistor and use that to drive a meter of
> your choice
> > - take some measurements to calibrate it and you are good to go.  This is
> the same
> > principle used on many true RMS meters in the past, just done in the
> "crude and
> > simple" way.  If you want more accuracy, an air gap of 6 inches with the
> bulb at one
> > end and the photocell at the other, and a photodetectorthat is sensitive
> in IR will
> > improve accuracy - a glass tube with the bulb at one end and the detector
> at the
> > other, painted black and wrapped with tape will do the trick.> From:
> > Gary.Lau@xxxxxx> To: tesla@xxxxxxxxxx> Date: Thu, 26 Jun 2008 14:54:37
> > +0000> Subject: RE: [TCML] HV Panel Meters> CC: > > You can use a
> standard
> > AC analog meter, but here's a couple things to think about.> > 1) You'd
> have to
> > take special precautions to ensure that all parts of the meter are
> thoroughly
> > insulated from a panel and contact with people. It's probably not
> advisable to mount
> > it permanently on a panel.> > 2) AC meters are calibrated to read RMS
> current, and
> > assume that the input waveform is a sine wave. The current drawn from an
> NST
> > into an operating Tesla coil does not remotely resemble a sine wave and I
> can't
> > offer any sort of conversion factor. So you might benefit form seeing a
> relative
> > indication, but the actual current value would be unknown. To get a
> useful RMS
> > current reading, you would need a true RMS meter, which typically being
> digital, is
> > subject to haywire behavior anywhere near a Tesla coil.> > Regards, Gary
> Lau>
> > MA, USA> > > -----Original Message-----> > From:
> tesla-bounces@xxxxxxxxxx
> > [mailto:tesla-bounces@xxxxxxxxxx] On> > Behalf Of Phillip Slawinski> >
> Sent:
> > Thursday, June 26, 2008 8:26 AM> > To: Tesla Coil Mailing List> >
> Subject:
> > [TCML] HV Panel Meters> >> > I'd like to set up some some meters to
> measure the
> > secondary side of my> > transformer [directly]. My question is if a
> standard shunted
> > mA current> > meter would be okay for this, or would I have to get a
> special high
> > voltage> > model?> > _______________________________________________>
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