Re: Mike Marcum Ferrite Cores >Terry look at this please<

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Mike" <mike.marcum@xxxxxxxxxxxx>

That too. Losses go way up with high freq (500kHz+) and high flux 
density. The 2k figure was for 500kHz and 80 degrees C (I think, have 
to look at the data sheet). They will work at 1MHz, but at only 200 
gauss for the same temp rise. There are some ferrites that can take 
alot more flux, but 2k is what the material in mine is spec'd at.

Mike
----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Thursday, October 20, 2005 1:57 PM
Subject: Re: Mike Marcum Ferrite Cores >Terry look at this please<


> Original poster: mecortner@xxxxxxxxxx
> Terry, I'm pretty sure My E-mail program messed
> this post up, this is the way it should be.
> Could you only post this one? Thanks.
>
>
> >Original poster: "Mike" <mike.marcum@xxxxxxxxxxxx>
>
> >Well, on my cores it's around 2000 gauss, but it 's not as fixed as
> >an iron core (changes with core material temp. which in turn depends
> >on flux density %:) ). I'm going for 90%+ efficiency (including the
> >half-bridge), so I'm shooting for 800 gauss or so (can't find the
> >paper where I did the calc's), which for a 2x2" core amounts to only
> >8+8 turns even at 370 volts 100kHz.
>
> >Mike
>
> No way! You mean for a 2" X 2" ferrite core the
> max flux density is only 2k Gauss?! How can that
> be so small? I've put some pretty big magnets on
> even small core cross sections and had at least
> half to two thirds of it come out the other side.
> Is this decrease some frequency related issue??
>
> ---- Matt Cortner ----