Re: AC Resistance (formerly Spice Simulation Pictures)

To: tesla-at-pupman-dot-com
Subject: Re: AC Resistance (formerly Spice Simulation Pictures)
From: "Edward V. Phillips" <ed-at-alumni.caltech.edu>
Date: Wed, 6 Nov 1996 17:37:47 -0800 (PST)

Re:
"Jack,

What do you think of this measurement technique?  Take your stand
alone secondary and place it in series with a carbon composition
potentiometer.  Apply a sine wave from a signal generator at
the resonant frequency of the secondary coil under test across the
coil-pot series circuit.  With a VTVM of sufficient frequency response, or an
o-scope, adjust the value of the pot until the amplitude across it
matches exactly the amplitude across your coil.  Now disconnect the
pot and measure its DC resistance with an accurate digital ohm meter.
This number is your Reff and also your Rac.

rwstephens

	This "substitution" method is an excellent way to
measure the effective PARALLEL resistance of a very high-impedance
or a very low-impedance (make that reactance) coil, in the region
where a Q-meter can't work well.  I have used it for years
and find it plenty accurate enough "for government work".
Ed Phillips