> how do i measure inductance of an inductor?

I assume you want an answer other than "use an inductance meter, of course".

The first thing I would do with an unknown inductor is measure the DC
resistance.  You will probably need to know this so you can account for it
when trying to measure the pure inductance.  In other words, you can think
of real inductors as a series combination of a resistor and an inductor.

The simplest way to measure the inductance is to find the time constant with
a known resistance.  Connect a known resistor to a regulated +5V supply and
the other end to the inductor.  Look at the resistor/inductor junction
voltage with a scope.  It should show 5V for now because the other end of
the inductor is unconnected.  When the other end of the inductor is
connected to ground, you should see an exponential decay towards ground
(almost, depends on inductor series resistance).  Adjust the resistor value
so that time constant is reasonable.  You can now compute inductance from
(time constant) = RL.


********************************************************************
Olin Lathrop, embedded systems consultant in Littleton Massachusetts
(978) 742-9014, olin@embedinc.com, http://www.embedinc.com

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