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

[PaulLowrance]

Paul,
I didn't catch your insights.
From what I understand is that the dipoles in the cores change from 1 to 4 as shown in below figure, right?
Are you saying that the permeability is changing as a function of dipole direction?
Maybe you can visualize what you intend to teach us here?

Hi,

That diagram looks correct. As the magnet approaches, the dipoles try to align with the NdFeB's magnetic field, but when the coil current turns on, the toroid dipoles easily align in a circumferential / longitudinal manner because it's a closed magnetic loop and also because this core is longitudinally annealed. 

[PaulLowrance]

Has anyone considered using a relay like Steorn? It seems Steorn likes a few turns, ~ 37, maybe to lower the inductance so as to reduce resonance from the battery. So few turns = ultra low DC resistance. I'm sure there are relays, and then there are relays, right? All relays have ultra low on resistance, but some might have even lower resistance. Also, how about switching speed, as it should be very fast, probably faster than 100 microseconds.

As for myself, I don't have any fast relays, so I'll using an IRF540. 

[Bruce_TPU]

Hi Bruce,

Is that price quote from Elna, or Metglas, or somewhere else?  My MAGAMP's, bought in 2007, were $2.65 each at 0.82" OD. Of course your core is a lot larger in all dimensions.

Hi Paul,

That price was from Elna.  My cores I have ordered are 1.06 inches OD.  The permeability is identical to what you had linked to earlier, but yours were 1/2" inch OD, too small.  The permeablility is identical, just the size is different according to Elna.

The smaller ones were only just over $2.00.  Huge price increase at the 1" OD mark...LOL

Cheers,

Bruce

[PaulLowrance]

I found it. Check out Steorn video at time mark 1:48 -->

http://www.youtube.com/watch?v=9JikYfmEdF8

Notice how thick the magnets are. You can see the size of the magnets. Maybe the magnets Steorn is now using in the demos are much thinner. What do you think?

[PaulLowrance]

Hi Paul,

That price was from Elna.  My cores I have ordered are 1.06 inches OD.  The permeability is identical to what you had linked to earlier, but yours were 1/2" inch OD, too small.  The permeablility is identical, just the size is different according to Elna.

The smaller ones were only just over $2.00.  Huge price increase at the 1" OD mark...LOL

Cheers,

Bruce

Hi Bruce,

Hey, actually the largest one in my elna order list were 0.82" OD.     But yes, I agree, that's a huge increase in price, but your core probably weights a lot more. Here's the specs:

My small core:
MP1805P4AS OD=20.83, ID=10.80, Height=6.76
Total volume = (pi*20.83^2 - pi*10.80^2) * 6.76 = 6737.46766 mm^3

Your large core:
MP2510P4AH OD=27.79, ID=17.27, Height=11.48
Total volume = (pi*27.79^2 - pi*17.27^2) * 11.48 = 17096.1645 mm^3

So your core has 2.5 times more material.  That still doesn't account for the price increase. That's probably good old influation.