Measuring the coil inductance Vs rotor angle by JL Naudin
created on december 27, 2009 - JLN Labs - updated on January 5, 2010
Toutes les informations et schémas sont publiés gratuitement ( freeware ) et sont destinés à un usage personnel et non commercial
All informations and diagrams are published freely (freeware) and are intended for a private use and a non commercial use.

Cliquez ici pour la version FRANCAISE

To go further in the understanding of the Steorn motor principle. This experiment shows the change of the inductance of the toroidal stator coil Vs the angular position of the rotor magnet.

I have used the Steorn motor v2 for conducting this test. I have measured the coil inductance with an inductance meter Voltcraft LCR-9063.

A graduated foam disk has been set in front of the rotor to measure the rotor magnet angle Vs the axis of the toroidal stator coil.


In the idle position of the rotor, the measured inductance of the right toroïdal coil is 1.38 mH


The right coil resistance measured is 3.9 ohms

Then the inductance of the toroidal coil has been measured with the inductance meter while the rotor angle goes from +30° to -30°

You will find the full video of the test below :

To summarize

This very interesting experiment shows that, while the rotor magnet approachs the toroidal stator coil, the coil inductance drops dramatically due to saturation of the ferromagnetic core. The middle spike corresponds to the position of the rotor magnet just in front of the axis of the toroidal stator coil. The lowest inductance point is the best angle to energize the coil (ignition point) and also the angle where the current spent is the lowest and thus the energy input is the lowest.

Interesting documents :

Email : JNaudin509@aol.com

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