>
> Does anyone know of a method of measuring the characteristics
> (permeability) of ferrite cores? I have a box of these most
> without any identification although I do have T200, 68-2T and
> T68-2s whose characteristics are known.
>
> It occurs to me that you can make a tuned circuit and measure
> resonance with a GDO when a ferrite core is inserted into the
> inductance. A graph could be made of the different resonances
> with different cores, to extrapolate the unknowns.
>
> However I think that ferrite bulk might be a problem. For example
> I guess the red T cores use the same material but would there be
> a difference between the T200 and the T68?
>
Since some are coloured, you can reasonably assume that they are powdered
iron rather than ferrite as the ferrite manufacturers, particularly Fair-Rite
and Ferronics, normally don't colour code their products, though Ferroxcube
does. These two Micrometals URLs should help:
http://www.micrometals.com/materials_index.html
http://www.micrometals.com/materials_index.html
Unfortunately, the tables provided by Ferroxcube do not provide the colour
coding information, so you'll need to go through the individual datasheets:
http://www.ferroxcube.com/prod/assets/sfmatgra_frnt.pdf
The recent reply by Marco provided a reasonable approach to sorting out
the permeability:
>
> just my 2 Eurocents... wound a few (5 to 20) turns, measure
> L and take physical dimensions of the toroid, use G4FGQ's
> toroid.exe, and then play with the parameters in the program
> to find wich permeability gives the L you measured. The
> program is pretty accurate, Reg did a nice job.
>
Chris
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