Alternative ways of finding the self resonant frequency of a coil.

[orangehorse]

Hello,
I have to wind a multi tapped toroid inductor, and i would need to find the SRF of the coil.
I do not have an oscilloscope, but i have a DMM, LCR,and a Function signal generator 1HZ-500KHz
with Sine, Triangle, Square Wave, and a PC with an external soundcard, with line inputs and outputs.

The coil should have 6 taps
from 29.9mH to 156mH


What i know is that i could get a dip meter and find the SRF very easily,
Is there any other alternatives to find the SRF of this coil?
I am on budget here, and i would only have to wind two coils.

Help is much appreciated.

All the best.

 

[VEBill]

Up to about 20kHz, you might be able to use freeware sound card oscilloscope software.

You might be able to rectify a sample of the signal of interest, and use the DMM to measure the resultant DC voltage.

Some recent DMMs can measure AC up to reasonably high frequencies; consult the spec sheet.

 

[JaPaBo]

What is anticipated SRF? I would guess (with limited context) at those inductance values, it's not particularly high. SRF may depend on tap configurations also.

Should be possible to measure total impedance and sweep frequency with your RLC meter in many cases. SRF will be at maximum impedance - start low and increase frequency until Z drops. I've used audio power amplifiers and a scope (or even a high end Fluke DMM) for frequencies < ~ 20 kHz for power magnetics, but it's basically the same concept.

Maybe some interesting step response measurement options where you excite a step and observe the resonant frequency.