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I want to buy a 1mH inductor. I am just making a basic LC filter and I see that there are "common mode" inductors.

I found one here with a data sheet: http://www.mouser.com/ds/2/355/DS_EV-EHseries_20110616_web19-8801.pdf

The inductor is 1mH and "common mode". Can I use this inductor to give me 1mH?(it meets my current rating too)

There are four legs on it as well. Will only using two of them give me half the inductance?

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    \$\begingroup\$ What John said. And, using one winding gives you 1/4 of the inductance, not half, as inductance is proportional to turns squared. \$\endgroup\$ – Russell McMahon Jul 10 '14 at 2:11
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Since it's a common mode inductor, it's intended to be used for a signal pair. For signals that are common to both conductors in the pair, it presents 1mH of inductance. Since the windings are counter-wound, for signals that are differential in nature (source on one conductor, return on the other) it presents (ideally) zero inductance. So if you wire it such that both windings are in series in the correct direction, you can use it as a 1mH inductor.

However, common mode chokes are typically designed to be lossy, so that the noise that they are filtering is dissipated as heat from hysteresis losses. Therefore it might not make a good single-ended inductor for your purposes.

Why not just get or wind a 1mH inductor that meets your requirements?

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  • \$\begingroup\$ ITYM "wire it in series". As well as John's other comments, the saturation current is not specified since there is not intended to be an imbalance in the currents between the coils, and if wired correctly in series, it will all be imbalance. \$\endgroup\$ – Spehro Pefhany Jul 10 '14 at 3:29
  • \$\begingroup\$ @SpehroPefhany Of course, you are correct Spehro, will edit to fix. Good point on the sat current too. \$\endgroup\$ – John D Jul 10 '14 at 3:51

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