Re: Inductance measurement

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <teslalist-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

At 05:33 PM 7/1/2003 -0600, you wrote:
>Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>" 
><Mddeming-at-aol-dot-com>
>
>Hi All,
>        Does anyone know how the resistance of a coil affects the measured 
> inductance using an LC meter (e.g. AADE LC IIB meter, Wavetek, etc.). I 
> am wondering if these meters really measure L, or do they measure delta Z 
> and infer L from it, with the built-in assumption that R<< XL ?
>        If I have two identical solenoids, one wound with copper wire and 
> the other with, say, Nichrome wire, would they read the same inductance, 
> or would the larger phase angle fool the meter?
>
>Matt D.

I'm pretty sure they ignore R and only measure L.  They, most likely, use 
some sort of quadrature detector to look for the 90 degree lagging 
current.  If nothing else, this lets them use a fairly crude excitation source.

The capacitor measuring scheme uses a constant current source and measures 
charge time to a given voltage, therefore is independent of series R 
(assuming that the current source has sufficient compliance)