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

[0c]

But there is one thing I don't understand if it's the way you say it is. Why does ORBO have such a big air gap between magnets and toroid ?

There are a lot of properties and the costs and benefits of each need to be balanced. If you compare Steorn's earlier video where they measure the change of inductance in a demo device, you will notice only about 30mH change in inductance. That's just a drop in the bucket compared to the several orders of magnitude change Max demonstrated in the supplemental video.

Also note that if you don't have a drop in permeability at TDC you will not have an inductance gain later.

True. So we want the permeability (inductance) up close to be lower than when far away. Not too hard to achieve that.

PS. To be honest the more we're analysing this machine the more I get confused ;] Still so much to understand and so low on time

Believe me, I don't understand it all either. If anyone does, it's Steorn and their insiders.

I noticed that the only factors given much consideration here have been permeability, inductance, and saturation. I think there is a lot more to this thing than that. So far, I have discussed how remanence can also fit into the equation, and that seems to have stirred things up a bit. There are some others I'd like to mention, once things settle down a bit.

[gravityblock]

If it was an AC application or if here were alternating magnetic fields, you would be correct.

Not true. The last state of the core is when the coil is deenergized. When that happens, the core returns to its remanent state which, if you look at one of the permeability vs. saturation references I provided, you will see is actually close to maximum permeability and maximum attractive force. In remanence, the domains in the core are already mostly aligned with each other and will rotate easily, reorienting to present an external field to attract the magnet even better as the magnet approaches.

You don't think the magnetic fields in the Orbo are alternating?  The magnetic field in the Orbo is going from low strength to higher strength when the magnets approach TDC from the view of the core, then go from higher strength to lower strength as they depart from TDC.  Isn't this an alternating magnetic field.   Remember, we're not sure if the pairs of magnets have the same orientation or not in the Orbo, and it may or may not have the same orientation according to a specific configuration.  Alternating magnetic fields can be used to return the core to it's virginal state or to a low remenance state.  I even have a video on it, but they use an AC current to do it, instead of magnetic fields from the magnets.

We don't know for sure if the last state of the core is when the coil is de-energized.  The pulse could be cut off when the core is still seeing a weak field from the magnets while the coil is still in a closed loop, which in this case could bring the last state to the point of coercivity (H_c).  Then when the magnets are approaching TDC with no voltage/current, but the coil is in a closed loop, the small increasing strength of the approaching magnets could bring the core back to a very low remenance state.  Then at TDC when the pulse is applied, the core is in a very low remenance state.

I have a feeling the toroids are in a closed loop most of the time, with only voltage and current flowing from TDC to 20 - 30^o past TDC.  With this in mind, try to think what the state of the core is in during each of the interactions between the magnets prior to TDC, after TDC, and the time the pulse is on for (also, do this same thought experiment when the pairs of magnets have a different orientation).  I think you will find this interesting.  To make it simple, they're using only half of a Minor Loop relatively speaking. They're using one half of the Loop more than the other half.  A Half Minor Loop with a near virginal state.  This is why my mind has been spit between the two methods, because they're using a combination of both methods.  I'm always thinking outside of the box.

GB

[0c]

You don't think the magnetic fields in the Orbo are alternating?

I don't think anyone but Steorn, SKDB members, or possibly someone who went to Waterways and tested Orbo knows for sure. But IF Orbo happens to gain anything from remanence, I think the rotor magnets should always have the same polarity.

The magnetic field in the Orbo is going from low strength to higher strength when the A approach TDC from the view of the core, then go from higher strength to lower strength as they depart from TDC.  Isn't this an alternating magnetic field.

If Steorn is using a low remanence core material, this would be true for their device. If a high remanence core material is used, most of the magnetization is retained when the coil is deenergized (as long as current with opposite polarity is not applied). The core is already magnetized as the magnet aproaches. The field from the approaching magnet will not contribute much to the flux density until quite close. What it will do is rotate domains in the core so the polarity will align with the magnet's polarity and the core's field will become unshielded and interact with the magnet until the next pulse is applied to the coil.

Alternating magnetic fields can be used to return the core to it's virginal state or to a low remenance state.  I even have a video on it, but they use an AC current to do it, instead of magnetic fields from the magnets.

That's why I said AC currents and alternating magnet polarities should be avoided with remanent materials.

We don't know for sure if the last state of the core is when the coil is de-energized.  The pulse could be cut off when the core is still seeing a weak field from the magnets while the coil is still in a closed loop, which in this case could bring the last state to the point of coercivity (H_c).

The fields from rotor magnets are more rotational than coercive. I used Finemet as an example. It's Hc is very small. There are other materials which can handle coercive fields better. If coercivity is a problem, a different material with higher Hc value can be used.

... they're using only half of a Minor Loop relatively speaking. They're using one half of the Loop more than the other half.  A Half Minor Loop with a near virginal state.

That may be the case. I don't think any of us knows for sure what Steorn is doing. In my discussion, I have concentrated on materials with high remanence.

Both sides of the minor loop can be utilized. The power-on side is used to reduce attraction between core and magnet. The power-off side is used to allow the inductance change to increase and increased return of power.

[gravityblock]

Here's a video on the Hysteresis Loop, http://www.youtube.com/watch?v=ddU6HBFlvEk

Please watch between 20:00 - 45:00 in the video.  Starting at 20:00 minutes he talks about the hysteresis loop. At 30:00 he talks about demagnetization and shows how to use an AC current to return the ferromagnetic material back to it's virginal state.  What he refers to as B_vac is actually the "H".

After the demagnetization experiment, he shows the retentivity of a material and the point of coercivity H_c.  Between 40:00 - 45:00 he does an experiment with a nail.  I am most interested in this experiment.  The magnet releases the nail when another ferromagnetic material approaches the magnet because the field of the magnet weakens on that side.  This probably doesn't have anything to do with the Orbo, but I find it most fascinating how the attraction force is weakened on that side.  I just wanted to bring it to everyones attention.

Here's a good site for anyone interested in learning electronics and magnetism.  Free education for all, http://www.edforall.net/index.php/sciences/physics/12-electricity-and-magnetism/267-magnetic-materials

Thanks,

GB

[gravityblock]

Here's another video on magnetic materials from MIT, http://www.youtube.com/watch?v=SNDqAuxYOQ8&feature=SeriesPlayList&p=C2CEECFD938FD494

Between 25:00 - 32:00 he does an experiment where you can here the domains flipping, and is known as the barkhausen effect.

GB