RE: mysterious coil failure / M and k Measurement (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Wed, 31 Oct 2007 15:39:33 +0000
From: "Lau, Gary" <Gary.Lau@xxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: RE: mysterious coil failure / M and k Measurement (fwd)

Hi Kurt:

It's a worthy goal to modify this measurement technique to eliminate the electrocution hazard.  But it's not clear to me that it's possible to achieve this without the use of a resistive ballast such as the hair dryer.  Placing a 6 volt transformer secondary across most TC primary coils would be essentially a short circuit and exceed the transformer's current rating.  Even if the transformer was driven with a Variac, I would worry that there might still be some non-linear behavior driving a near short-circuit, resulting in non-sinusoidal waveforms and inaccurate measurements with common DMM's.

Or, are you proposing to still use a suitable (?) ballast on either the primary or secondary side of the xfmr, and make sure that the xfmr secondary current remains well below its rating?  What is the minimum TC primary current that results in an induced TC secondary voltage high enough to stay above the noise?

Regards, Gary Lau
MA, USA

> From: Kurt Schraner <k.schraner@xxxxxxxxxxx>
> To: Tesla list <tesla@xxxxxxxxxx>
> Subject: Re: mysterious coil failure / M and k Measurement
>
> The safety concerns, regarding the circuit at Bart's site:
> http://www.classictesla.com/download/M_and_k_Measurement.gif
> can be eliminated, using a downstep transformer (i.e. Vout=6...12V; some
> Amps), inserted between the mains AC line and the rest of the circuit. And
> voltage may optionally be adjusted, by using a variac. This allows much
> quicker measurement at different taps of the primary.
> BTW, I'm also taking the measurements without the RC combination accross the
> secondary.
>
> Regards, Kurt
>
>
> Tesla list wrote:
> > ---------- Forwarded message ----------
> > Date: Mon, 29 Oct 2007 13:04:46 +0000
> > From: "Lau, Gary" <Gary.Lau@xxxxxx>
> > To: 'Tesla list' <tesla@xxxxxxxxxx>
> > Subject: RE: mysterious coil failure (fwd)
> >
> > One doesn't need a signal generator or scope of any kind to measure
> > coupling.  You need only know the primary and secondary inductance,
> > and perform the measurement described at
> > http://www.classictesla.com/download/M_and_k_Measurement.gif
> >
> > I've not found it necessary to include the RC network across the
> > secondary.  The wording is confusing with "Take concentric readings
> > from meters."  I think what was meant is to take both primary current
> > and secondary voltage measurements at the same time on separate
> > meters.
> >
> > Regards, Gary Lau
> > MA, USA