STEORN DEMO LIVE & STREAM in Dublin, December 15th, 10 AM

[gravityblock]

@Ossie:

I'm impressed with your latest video.  Enough turns to saturate the core to let the magnets pass by but not many layers which decreases the distance from the core to the rotor magnets for better attraction between them.

Oh, thank you for your winding technique you posted earlier in this thread.  Keep up the good work and thanks for sharing.


GB

[Jimboot]

Vid of my first working motor. http://www.youtube.com/watch?v=7AOLTk24ib0 based on @callanan switching circuit. Thanks again Ossie.

[gyulasun]

Here is a data sheet such ferrite "washer" exist, obviously this is one sudden find,  many other manufacturers should have thin ferrite rings.

From the link below, for instance
   
   OD   ID   h  (in mm)
   
T  12 x 5.5 x 3 
T12.7 x 7.9 x 5
....
T 18 x 10 x 4

http://www.cfe.com.tw/core-emi-shiled-and-toroidal.pdf 

All in case the metal washer may introduce eddy current losses.

rgds, Gyula

[gyulasun]

Vid of my first working motor. http://www.youtube.com/watch?v=7AOLTk24ib0 based on @callanan switching circuit. Thanks again Ossie.

I got: This video is private.

??

Gyula

[exnihiloest]

I carried out new measurements today on permeability change of toroid cores under magnetic fields from permanent magnets.

There is change of the permeability viewed from the coil only when resultant components of the magnet field saturate the core somewhere along circles that pass inside the torus and have the same center as the torus.

When the field from permanent magnets is transverse to the toroid plane along the whole core, there is no change of the permeability viewed from the coil (same inductance).
Thus the permeability change due to saturation depends on the direction of the field. Permeability is not isotropic.

There must be some alignment of the magnetic domains along the circles in the torus in order to obtain an effect on the inductance. Only in this case a current in the coil will repel the magnet or prevent it to be attracted back. But as viewed yesterday, this implies action/reaction between the magnet and the coil, and Lenz's law applies.

When the magnet field is uniformly perpendicular to the plane of the torus, a current in the coil causes no force onto the magnet, because the two fields have independant actions. Even though the magnet aligns the magnetic domains in a transverse plane and saturates the core in this direction, the field due to the current in the coil can still rotate them because there is no saturation in its own direction.

The "Steorn effect" (if real) cannot be due to a simply handle of the permeability as asserted by JL Naudin.