Measuring Inductors

[Paul Marossy]

Is there a way to measure an inductor to find out what value it is? Can you do it with a DMM?

[Mark Hammer]

You can do it with a really *EXPENSIVE* DMM, but I rarely if ever see inductance measurement in anything selling for under $100US. :cry:

[Rob Strand]

You can do it if you have a sinusoidal source and an multimeter with an AC range (and some resistors and caps).  Preferably the sinusoidal source is a bench-type audio oscillator with variable frequency and output level, but with some inductors you can use 50Hz/60Hz the output of a mains transformer.  The idea is you take some measurements and plug the numbers into an equation to get your inductance value.

There are *many* different methods, do a web search and find one which suits the equipment you have.

[Brett Clark]

Do you already have a capacitance meter? IIRC, there was an article in Popular Electronics or somesuch a few years back about a simple gyrator circuit to measure inductance with a cap meter.

As for me, I used to use the resonance method, but I finally broke down and bought a real LCR meter. They're not cheap, but if you work with tube amps much, the savings in transformer diagnosis accuracy/speed makes it worth it.

[hodad]

Newark has a Tenma LCR meter for about 50 bucks.  It's the cheapest one I've seen.

[Paul Marossy]

Thanks for the help guys. I was remembering that there was a few ways to measure inductance, but I couldn't remember... I've never had to mess with it until now.