ok, so how would i do it with a pic?  i assume i would have to measure the
decay time and know the resistor value and then compute it and display it.

andy
----- Original Message -----
From: "Olin Lathrop" <olin_piclist@EMBEDINC.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Thursday, May 31, 2001 7:17 AM
Subject: Re: [EE]: measuring inductance


> > 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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