View Full Version : Inductor characterization


dtvmcdonald
07-07-2014, 07:58 PM
While thinking of the "white crud" coil problems of CT-100s, I
thought of "how do you adequately characterize an inductor?"
so one that matches that characterization "just works".

It would seem that you need four numbers:

1) Inductance at low frequency

2) DC resistance

3) parallel resonant frequency

4) Q at parallel resonant frequency

I was also thinking that for air core coils #4 might
be superfluous. Clearly for magnetic core ones it, or something like it,
such as Q if resonated at the expected operating frequency,
is necessary. It would also be necessary for shielded coils.

Does anybody KNOW the answer to whether this is good enough?

Doug McDonald

bob91343
07-08-2014, 10:43 AM
How about inductance vs. direct current? Q at low frequency? And Q at resonance has little meaning, since by definition there is no reactance there, and Q is defined at reactance divided by resistance.

dtvmcdonald
07-08-2014, 10:56 AM
Ah, you are right about inductance versus DC in non-air-core coils.

You're wrong about Q at resonance, since resonance is a two-part thing:
Inductance with effective resistance in parallel with essentially
perfect capacitance. The Q is that of the inductor alone.