Re: [TCML] HV Panel Meters

["Phillip Slawinski" <pslawinski@xxxxxxxxx>]

I mean secondary current and voltage on the NST.

On Fri, Jun 27, 2008 at 8:39 PM, bartb <bartb@xxxxxxxxxxxxxxxx> wrote:

> Hi Phillip,
>
> A CT such as Pearson sells and a scope with storage capability is probably
> the most accurate for current readings. As far as voltage readings, your out
> of luck. You can perform estimate testing, but you won't be able to measure
> the actual voltage at the top of the coil with a meter. Maybe with some
> really nice expensive equipment, but for the run of the mill stuff, not
> likely.
>
> Take care,
> Bart
>
> Phillip Slawinski wrote:
>
>> 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?> > _______________________________________________>
>>>> Tesla mailing list> Tesla@xxxxxxxxxxxxxx>
>>>>
>>>>
>>>>
>>>
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