I have a multimeter that can measures Capacitance, Resistors, voltage and current.

If I have a known coil and unknown coil.

Can I measure the ratio between the inductance of the two coils ?

Is it possible to determine the inductance of unknown coil ?


Place the known and unknow inductors in series and apply a known AC voltage across the pair of them. Best to use an o-scope for this but it's not beyond impossible to use the multimeter on AC measurement.

The sum of the voltages across each inductor will add up to the voltage applied across them both. If the two inductors are equal then the voltage across either will be the same. The smaller inductance will have a lower AC voltage.

Use the voltage ratio to determine the ratio of the inductors. For instance a 2H coil in series with a 1H coil will have twice the voltage across it compared to the 1H coil.

  • \$\begingroup\$ +1. I think it would be good to mention the thing you describe is called an inductive voltage divider. \$\endgroup\$ – Phil Frost Oct 22 '14 at 21:57
  • \$\begingroup\$ You've saved me the trouble LOL \$\endgroup\$ – Andy aka Oct 22 '14 at 22:09

For an unknown inductor I usually resonate it with a cap near the frequency of interest.
A 'scope is certainly best for this, because it's nice to see the phase relation as well as the amplitude. I guess you could do it with a signal generator and AC voltmeter (DMM), you'd want to check the frequency range of the DMM.


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