Permanent magnets as coil cores?

What are the benefits of using a permanent magnet for a coil core. I recently came across a design for a switching power supply that used magnets as cores for the inductor. I have never heard of such a thing, except maybe in speakers.

Reply to
vinhkan
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If there is DC current flowing in the coil, it reduces the amount of flux "swing" that can happen without saturating the core. Or looking at it from another angle, you need a physically larger (more $$) core to do the same AC work if it is also carrying DC. Using a permanent magnet to counteract the DC flux allows a smaller (cheaper) part to be used. Used to see these in the vertical section of TV's in the days before power IC's.

Reply to
Ol' Duffer

Your use of Usenet

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needs improvement.

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Reply to
JeffM

I suspect it was the horizontal, not the vertical, circuit, and its purpose is to provide two different inductances, one for "positive" currents, and a different one for "negative" currents. Those are used to provide linearity correction.

Isaac

Reply to
isw

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*-*-*-*-*-*-*-*-appear+*-proper-answer-*-*-*-given+much-easier-*-*-*-*-*-*-*+*-frowned-on+*-correcting+*-Followup-To-*+*-*-_perfect_-*-*-*-*+*-*-*-too-lazy-*-*-*-*-*-appropriate-*+*-polite-*-mention-*-*-*-*-*-*-*+Just-because-*-*-*-*-*-*-*-*-does-not-mean-*-*-*-*-*-*+mark-*-*-*-*-all-*-groups+*-*-*-*-two-groups-*-*-aren't-*-different

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Reply to
Ol' Duffer

Why don't you find the person's email and send to them directly? There's a much greater chance that they will see your response.

Your repeated posts about multi-posting take more bandwidth than the people you are faulting.

Get a life...

Reply to
John

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