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

[captainpecan]

Hi,

The cores are only $2.65 each, and so far it appears to be the best matching core to Steorn's. I would think people would want to be encouraging to buy these Metglas MAGAMP cores, not discouraged, right?

Lol, actually I'm very much encouraging you to buy them!  That way I can try something different and compare results...  There is nothing wrong with giving them a go, who knows, they may be the exact cores Steorn is using.  But I do think it is important to try other options too.  There always seems to be a trade off somewhere when you choose materials for a build.  But in this case, I do not think Steorn cares at all about torque.  It's about getting more from the return of a pulse than what was put in.  The rotation is just a bonus I believe, but necessary for fast switching.  Paul is right on this one, it's a great idea to give these cores a whirl!  Mine is built with 4 cores of thin steel, and 1500 turns on each.  I've got a good runner at very low voltage and amperage but it's far from as efficient as my bedini is right now.  I'm rebuilding my rotor and everything to better suit Steorns original design and see what I can do.  Mine is just not anywhere near OU.

[PaulLowrance]

But I do think it is important to try other options too.

I agree, but since the Steorn showed the inductance measurements of the core it's not even worth for *me* to try common cores because it's just physically impossible to fit 27 *layers* (@ 37 turns per layer = 1000 turns) with that wire.

I already have the Metglas MAGAMP cores, and just about every other type of Metglas core that Elna carries, which includes the transversely annealed cores with only 80000 permeability. 

[0c]

But I understand that those cores are yours to do with what you will.  It was only a request.  I'd just hate to see a bunch of people order these cores and then find a PM is not as attracted to them compared to one with slightly less permeability.

It's probably best to do this type of testing with a gap anyway, like maybe 1/4" of plexiglass to separate the magnet and core material. Recent NdFeB magnets are capable of producing a surface field that would completely saturate the metglas and reduce permeability as it did, thus reducing the attraction when in contact.

Permeability is just the material's affinity for magnetic fields. You would want to test the maximum values (at a distance) instead of the contact value. Steel would likely do better with a high-power neo magnet in contact, simply because it won't be saturated yet and permeability will be near its maximum.

[PCB]

Just watched the videos from yesterday. Very interesting, a lot of good information. Should be possible replicate given the information available. Perhaps someone could help me with some information that may have been posted earlier.

@PaulLowrance. I agree with you that the cores have to have a very high permeability. I also count about 36/38 turns (one layer). Give the size of the core what would you estimate the gauge of the wire to be? I should be possible to measure the inductance of the winding to conform that it is in the same range as given by Steorn in their video test.

There is a micrometer on the top of motor. Does anyone know what bearings there are using? It should be possible to make this mechanism, micrometers are pretty cheap on ebay. Could be re machined just to use the micrometer mechanism.

Sean had a circuit diagram on the overhead projector. Has anybody posted what that was?

Lastly, I thought @Airstriker gave a good explanation earlier on the generally theory of operation based on the equation for an inductor that did not seem to get much play in the forum.

[gravityblock]

Good catch Paul.  You can actually see the core and I only see 1 layer of 37 turns as you suggested.  This is the reason in having a "deep battery" to deliver a fast almost instant current to saturate the extremely high permeable core.

Magnetic viscosity determines how much energy it takes to saturate.  If the domains turn easily, then it takes less energy to saturate a high permeable core than to saturate a low permeable core where the domains don't turn easily.  This is a low voltage and high amp system (relative to each other).  Very little resistance in the entire system.

I think there is enough known information now in order to have a successful replication.  There may be other unknowns, but the answers will probably be in the videos and in what is openly said.  They don't appear to be hiding anything and are giving us many good clues to point us in the right direction.

Good job Paul!


GB