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

[exnihiloest]

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If you have a 5 ms pulse.  During the 1st ms, the votage is turned on, and the current follows slightly behind it due to the permeability of his cores.  This takes lets say 2mw of energy to build the field.  On the 5th ms, the connection is broken and field collapses.  This time the inductance of the coil was higher and now we get 3mw back out of it.  2mw in, and 3mw out... an energy gain...  But only if you forget about 2nd, 3rd, and 4th ms that the energy was being used to keep the field built up.
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Any thoughts...  Am I looking at this wrong, or hearing him wrong?

I asked me the same question. It is not possible to obtain a pulse constant in current and voltage when powering a changing inductance.
When the inductance increases the current should be decreasing.

Possible explanation for both this question and also the functionning with reversed current pulse:
The magnetic flux from the moving magnet is not balanced inside the toroid core, thus it induces an emf in the coil. As the voltage is kept constant by the pulse generator, it follows that the current decreasing because of increasing inductance is compensated by the current provided by emf from the magnet motion (Lenz's law).
When the pulse polarity is reversed, the effect is the same, because the Lenz's law goes always against the variation of flux and not against the absolute direction of the flux.

[exnihiloest]

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Since current stays constant on the input side of the equation and we have change in Inductance on the right side of the equation (due to ORBO interaction), what we end up with is a gain in magnetic field energy !!
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It is generally true, but a wrong statement in the present case. Even though the coil is toroidal, the rotor magnet motion induces emf in the coil, and thus provides current that is supposedly free.
Why? Because the magnet modifies the toroid core permeability but the permeability is not constant along circles that pass inside the torus and have the same center as the torus. The core cannot confine the flux because of core parts having higher permeability than others. The flux in the sections of higher permeability cannot pass fully through the sections of lower permeability (these more saturated): the field lines have to loop outside of the core. Thus it is a classical functionning of a coil in the field of a moving magnet, the only particular thing being that the coil inductance is field dependent. This kind of motor is known as "parametric motor".

[Airstriker]

the rotor motion induces emf in the coil and thus provides current that is supposedly free

No it doesn't. When the magnet is approching a coil, the coil's circuit is open so there is no current. Then at TDC we saturate the core. Since the core is fully saturated it's "invisible" for the magnets and vice versa. Just put a simple saturated toroid and a magnet in the FEMM simulation. Does the field lines of the magnet penetrate the toroid ?

[gravityblock]

I think the thermal imaging camera suggests an inner and outer core material.  Both the inner and outer core being made up of a different material.

http://www.youtube.com/watch?v=ib9u811WXJU  Take a very close look at 7:25 to 7:27 in the video.


GB

[teslaalset]

Naudin has posted a new coil test on inductance of his latest rig.
http://www.youtube.com/watch?v=ww-F5MfWSGA&feature=sub

He shows also quite high values in Henries near 1 H.
As far as he indicated he uses ferrite as coil material.

In my view Steorn just uses simple ferrite cores.
Ferrite is able to handle high frequencies and has a permeability of around 4000.
Mumetal is not able to handle fast switching without significant losses as far as I am informed correctly.