RE: [TCML] HV Panel Meters

[William Noble <william_b_noble@xxxxxxx>]

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?> > _______________________________________________> Tesla mailing list> Tesla@xxxxxxxxxxxxxx> http://www.pupman.com/mailman/listinfo/tesla_______________________________________________
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