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ferrite torrid with smallest B-H curve

kappa_am

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Hi everyone,
I am looking for a magnetic material preferably available in ring shape with smallest B-H curve. I mean it goes to saturation with very small A/m value and also it has low saturation B.
Smaller than N87. smaller better.

Thank you
 

FvM

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I suspect the question is based on an error of reasoning. To get saturation at a low field strength H, you want high permeability and lower core cross section, e.g. using T46 or 3E9 material.
 

kappa_am

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If I am wrong please correct me; If saturated value of B is same for all cores. But I think it is deferent. For example, Amorphous cores go to the saturation with smaller H value, but with same core size saturated B value is almost 10 times of N87,... .
I need material with quite opposite characteristics get to saturation in low H and has low saturated B value ( low permeability).
Is there any core material with this characteristics?

Thank you
 

BradtheRad

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A ferrite bead might be suitable (although I don't know how to apply the specs being discussed).
I used a tiny bead with holes to make a 'joule thief' voltage booster.

Instructions say how to run wires through it, turning it into a transformer. An explanation tells how the transformer saturates during operation. It carries a few tens of mA.

bigclive.com/joule.htm
(Photo showing size of the ferrite bead)

joule8.jpg
 

Easy peasy

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for a non gapped toroid, the B is only material dependent up to the saturation point of the material,

B = Uo Ur H = Uo.Ur Ipk N / length-mag-path

so you can either make the ave circumference of the toroid/bead as small as possible, or add turns to the toroid/bead or have a material with a very high Ur, which will get you to saturation at lower through current, however these types of material, if ferrite, often have higher losses, cores like metglas have very "square" B-H loops which get you to saturation for lower currents ...

Toshiba "ammo beads" is/was a brand that may well embody what you are seeking, now this:


and:

and: https://www.google.com/url?sa=t&rct...f-357300.pdf&usg=AOvVaw2l8iyBtVJwXWlhldYd9i9X
 
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