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How do i measure inductance?

Discussion in 'General Electronics Chat' started by Glyph, Jul 9, 2004.

  1. Glyph

    Glyph New Member

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    As the question suggests, how do i measure inductance?

    The inductance measuring modes of multimeters doesn't precisely measure very low inductances on the order or microhenries very well. Is there a circuit or a method for measuring inductance to say 0.1uH? preferably 0.001uH?

    Thanks
     
  2. John Sorensen

    John Sorensen New Member

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    Measuring inductance (and capacitance) is tough, short of a LCR meter. If you do a search on the internet you can find some L meter circuits, but they're kind of dubious.

    I made a C meter, which is pretty easy using a microcontroller.

    For inductance, what I do, when I *have to* is put a capacitor, (whose value is known) in parallel with the inductor, charge it up, disconnect the source, and measure the period of the oscillations, then calculate the L. As I mentioned, I only do this when I *have to*.

    j.
     
  3. zachtheterrible

    zachtheterrible Active Member

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  4. dave

    Dave New Member

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  5. Glyph

    Glyph New Member

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    Pulse counting i suppose is a straightforward way of doing it. Thanks for the suggestion John.

    Is there anyway to say measure the saturation current of the inductor? or in effect measure the inductance at various levels of current? I'm expecting my inductors might be handling brief periods of high DC current (say 50 amps) during operation and i'd like to know how much the inductance would drop during those periods.

    As for calculating the inductance as zack mentioned, its possible, but since i expect to be using some ferrite the inductance will be very different from calculated.

    Thanks for your help and more thanks for any future help :)
     
  6. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    As you mentioned 50 amps, and ferrite cores, presumably this is for a switchmode power supply?.

    Ferrite core manufacturers usually give you all the design details in their datasheets - have you tried looking there?.
     
  7. chemelec

    chemelec Well-Known Member

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    Here are some calculators on my website.

    Most calculators on the internet don't take into account "Wire Insulation Thickness", Therefore they create large errors on smaller gauges of wire, so they don't even show them.

    My calculators do account for this insulation factor so I give a full range of wire gauges, including most half gauges. I have also varified these calculators with various test coils that I have wound and tested.

    http://www3.telus.net/chemelec/Calculators/Calculators.htm

    Take care........Gary
     

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