DIYbanter - Ferrites, L changes with current Change

Fred Abse a écrit :
On Sun, 20 Dec 2009 23:30:29 -0600, amdx wrote:

This graph was posted by Fred Bartoli.
Notice how inductance drops of with lower drive voltage.
This graph only goes down to about 0.4VRMS.
I wonder what happens at .000001VRMS?

I wonder how you're going to reliably measure it at that level?

That's not so difficult...
Make a tank circuit with the inductor, couple it very loosely to a
generator, then amplify the signal from the tank and input this into a
VNA or such.

But the real question is: is this worth the trouble?

Those graphs were done with a special setup, because I needed "high"
voltage, and I just didn't had use of lower test voltage for that
application. Also the setup was wideband and SNR wasn't great at really
low voltage. That's why the curves stop where they do.

Later, out of curiosity, I did check down to the 1mV level (the lower
limit of all my analyzers) and didn't see any further decrease.

amdx might have a look at how hysteresis curves are 'explored' with
varying signal levels.

--
Thanks,
Fred.