Hysteresis is a gap in which a iron or ferrite core needs a more intense magnetic field to magnetize, retaining a bit of the field after the current has been removed.
"Just good enough" wins most of the time.
The opinions of engineering and marketing and sales are not the same, and who wins determines what is used. NOTE: Sometimes practical reasons determine what material and shape of transformer are used, which is not always the best choice. Large toroids need expensive winding machine heads so toroids are better used at low voltages were the number of windings is low, such as car stereo power supplies.
#10MM FERRITE CORE INDUCTOR PC#
PC power supplies can put out over 1,000 watts and they use E cores as they are easy to wind by machine, and can have a cross section large enough to handle as much as 10 ampere/turns, and a tiny 10 mil air gap helps a lot. This chart is generic as it is not including fine details such as permeability, and does not state if iron, steel, ferrite or permalloy, which is a nickel-iron alloy. Green is low frequency filters made with silicon steel tape wrapped to form a toroid. Blue is an expensive Permalloy that is more efficient than ferrite. Black ferrite is usually a good choice for transformers. But a side effect is that it has very low permeability. There is a color standard for painted toroids, and yellow means it has hysteresis to prevent saturation and is meant for filter inductors. (PS: Also another reason I ask, is that at my place, the ferrite cores are half the price of the iron powder cores.) But, are they also good for higher currents (like 5-6 A peak)? I'm guessing the ferrite toroids are great at low currents (0-100 mA) and low frequencies (<100 kHz, as I can get more inductance with fewer turns). Will this matter if the peak current through the inductor is limited? many more turns for the iron powder core. I have some toroids and an LCR meter, and the ferrite toroid needs only a few turns of wire to get a 1 mH inductor, vs. įrom searching on the Internet, the yellow white toroids seem to have a permeability of 75, and the ferrite has a permeability of 2300 or so. Most of the buck converters seem to use the yellow white iron powder toroids, like this. I'm planning on using the cores for buck converters (mostly 3 A at probably below 200 kHz).įerrite: (also available in 13 mm outer diameter)
Will the ferrite toroids saturate at 5 A current? I'm wondering about the difference between small (13 mm outer diameter) ferrite and the yellow white iron powder toroids.
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