RE: Gary's inductance measurement Was: Inexpensive LCR-Multime ter

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

Original poster: "Mccauley, Daniel H by way of Terry Fritz <teslalist-at-qwest-dot-net>" <daniel.h.mccauley-at-lmco-dot-com>

Because inductance does vary as a function of frequency.  Generally, the
higher the frequency, the higher
the inductance is.  (Up to its resonant frequency of course)
With a tesla coil primary coil, I would expect the inductance to be
relatively constant at low frequencies.

However, when you start building chokes using different types of cores, you
start getting huge differences in
inductance over different frequencies.

For example, if you tried creating a high frequency choke using a
non-ferrite core, you might find you have 100mH at
say 100 Hz, but when measured at 30kHz, the inductance may only be 10uH.

Dan


 >Why is it necessary to measure inductance at different frequencies?
 >My characterizations of different primary coils with a _very_ expensive
 >HP4194 impedance/gain-phase analyzer showed negligible variation of
 >inductance with frequency.