Re: Coupling Experiments

In-Reply-To: tesla-at-pupman-dot-com -- 05/20/96 15:25

Hi Skip,

Here's an unsolicited suggestion on how to make a solid measurement of the
mutual inductance, using only a variac and a voltmeter:

Apply as much 60Hz AC current to the secondary as it will comfortably take.
(consult wire tables)
Measure the 'open circuit' voltage of the primary.

The mutual inductance = Vp / (Is * 377),  derived from Vp/Is = 2*pi*F*Lmutual.

I usually omit the variac, and just throw 120 volts across the secondary,
which yields about 0.25 volts RMS on the primary for k=0.15 .
It's a quick measurement method, with about a 1% accuracy in my case.