Re: Mike Marcum Ferrite Cores

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Malcolm Watts" <m.j.watts@xxxxxxxxxxxx>

Hi Matt,

On 15 Oct 2005, at 6:06, Tesla list wrote:

> Original poster: mecortner@xxxxxxxxxx
>
> Original poster: "Malcolm Watts" <m.j.watts@xxxxxxxxxxxx>
>
> It depends on your application and the grade of ferrite in the
> transformers being compatable. Some recent colour monitors seem to be
> using 3C8 grade but they once used 3C6 which is nowhere near as good
> at 100kHz.
>
> Malcolm
>
>
> Hi Malcom, it seems you know something about ferrite
> materials. All I know is it should have low hysteresis
> and low eddie currents loss but other than that I'm
> in the dark. The generator will put out frequencies
> from 50 Hz to 500 Hz but mostly 60 Hz for driving
> NST's for coils. What material do you think would
> be best?

Just about anything including signal grade ferrites (Philips 3Hx,
even 4Ex series) at those frequencies. The grain size is easily small
enough to obviate eddy currents. Hysteresis losses can be reduced by
gapping the material if they are a problem. If you have some ferrites
on hand and know the grades, you can try and obtain data from the
manufacturers or simply "Googling" them. Low hysteresis losses are
signalled by a small enclosed area in the B-H curve. At low
frequencies AND high signal amplitudes you are going to need high
inductances to minimize the risk of core saturation which, if the
core is gapped as well, implies large core size. A definite design is
going to depend heavily on design requirements and there is not
enough data given to go on (yet).

Malcolm