I've just joined. I'm located in the U.K. and am a retired electronics engineer. I was looking for a method of measuring the self-capacitance of a coil and found this site and this article. Am now reading it . . .very interesting . . . .
Hi and welcome to the forum,
When i saw this thread i thought it was more recent, so i read a little more of it first. What really puzzled me was that so many people replied in a manner that would allude us into believing that there is no capacitance associated with a coil. That very surprising because i am pretty sure the people who replied would know that there is always some capacitance in very coil, and it is sometimes important to know, such as the reply from one member who talked about self resonance. Sometimes we can ignore, sometimes not, it all depends on the application.
I do have a feeling though that the OP was using the word "capacitance" in a more general way however, so more like asking about the 'capability' of a coil rather than the actual capacitance, but i just thought i would mention this in passing.
One way would be to see how it oscillates...at what frequency...then use the LC formula for frequency solving for the capacitance. So starting with:
or in alternate form:
then we solve for C:
and if you care to square that:
and there you have the capacitance.
You may wish to include an error capacitance term:
where you might guess at the test jig capacitance Cerr as that would change the capacitance, or use a calculation.