Let me offset the "Bad Cop" posting with a "Good Cop" posting.
Gravityblock provided a link to a Hitachi Metals "Finemet" product brief:
http://www.overunity.com/index.php?action=downloads;sa=downfile&id=362It appears that Metglas use the Finemet materials to make some of their cores.
Please have a look at the second page of the brochure where you can see DC B-H curves (a.k.a.: "hysteresis loops") for three different types of Finemet materials, H-type, M-type, and L-type.
It is pretty obvious that Metglas uses the H-type material for their Metglas Magamp-style cores. The H-type uses a circumferential magnetic field during annealing to give it the desired property, a "square" hysteresis loop. Again, to repeat, this is the type of core that everybody is all excited about and I think that you are all wrong.
Have a look instead at the L-type core material. For this material a magnetic field is applied vertically to the core plane during annealing. Take a look at the hysteresis loop for this core material.
This loop shows you that when you stop energizing the toroidal coil wrapped around the L-type core material, the core material will loose almost all of its induced magnetic flux. Therefore the core will "reappear" so that the magnet on the rotor will become attracted to it.
You absolutely need to have the core
disappear and then
reappear to have an efficiently running Orbo-style motor.
In contrast to this, the hysteresis loop for the H-type material will retain almost all of its induced magnetic flux when you stop energizing the toroidal coil wrapped around the core. Therefore the core will barely "reappear" so that the magnet on the rotor will barely become attracted to it. This means that every time that you go to energize the H-type core, it is already nearly completely saturated and thus the pulse energy is mostly wasted in this case.
I acknowledge that I am not factoring in the external magnetic field that comes from the moving magnet. It looks to me like it will partially rearrange some of the magnetic domains in the H-type material for the unenergized coil, which will create some attraction between the magnet and the core. The main point is that if we make the assumption that the approaching magnet will not be able to rearrange the already-lined-up magnetic domains inside the core, then the magnet will be barely attracted to the H-type core. Again, this is because the core will be already nearly completely magnetized when the toroidal coil is not energized because of the nature of its B-H curve. This magnetization will prevent the magnet from being attracted to the core. The only way to overcome this problem would be to demagnetize the core after the energizing pulse is over, each and every time. That would require extra electronics and extra power.
For the sake of completeness let's look at another scenario: The neo magnets on your rotor are so strong that it doesn't really matter if the toroidal core is made of H-type or L-type core material. Either way the overwhelmingly strong magnetic fields from the neo magnets will rearrange the domains inside the core material, whether they are already aligned or not, and there will be an attraction phase. If this happens then what is the down side for the H-type core? The down side is that the "battle" between the strong magnetic fields of the neo magnets and the already-aligned magnetic domains of the H-type core represents
lost energy. Every time the neo magnet passes by the already-aligned H-type core and rearranges it there is an energy burn - the rotor slows down and the core gets hot. That is a situation that you want to avoid.
In my opinion you have chosen the wrong core material to make the pulse motor run. You want a core with low coercivity, a "soft" magnetic material that looses almost all of it's magnetism when you stop energizing. You absolutely need that property to make your motor run well. You also want a core material with as small an area inside the hysteresis loop as possible because the area inside the hysteresis loop represents lost energy in the form of heat.
A few choice Wiki quotes:
http://en.wikipedia.org/wiki/CoercivityMaterials with high coercivity are called hard ferromagnetic materials, and are used to make permanent magnets.
The squareness (M(H=0)/Ms) and coercivity are figures of merit for hard magnets although energy product (saturation magnetization times coercivity) is most commonly quoted.
The coercivity is a measure of the degree of magnetic hysteresis and therefore characterizes the lossiness of soft magnetic materials for their common applications.
A material with a low coercivity is said to be soft and may be used in microwave devices, magnetic shielding, transformers, or recording heads.
Finally, here is a choice quote from Overunity.com. It is what I see when I go to the site:
Sorry MileHigh, you are banned from posting or sending personal messages on this forum.
Twisting facts in the Steorn topic
Your ban is not set to expire.
That statement above is absolute bullshit, and you can read what I have posted on this thread and on the OU thread and decide for yourselves. I am just trying to give you my opinions and some facts on the whole Steorn/Orbo/replicators issue. I don't claim to know everything or be right all of the time. If you think that I am a liar, or a "paid disinformation agent", or I work for "Big Oil" then you are a nutcase as far as I am concerned. If some of you are with me then you realize that I am trying to help you develop some critical thinking skills to evaluate what Steorn is doing for yourselves. I think that Steorn are fakes, I have no problem putting my cards on the table. However, my point of view doesn't necessarily mean that everything I say about Steorn is a "spin" to bash them because it's not.
People that have ordered Metglas "Magamp" style cores should also order Metglas cores that are based on the L-type core material. I predict that you replications will run much much better with cores based on the L-type material.
The next time one of these design issues comes up I strongly suggest that you have a
real debate and discuss
all of the aspects of the design choice.
MileHigh