Re: Mike Marcum Ferrite Cores

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Original poster: mecortner@xxxxxxxxxx 

>When a core saturates, it simply does not produce any more magnetic
>field. Its reached its limit, so your inductor basically turns into
>a resistor (goes from energy storage device to energy dissipative
>device). This is why saturation is to be avoided.


Hi Steve.

I bet that's why generators of all types tend
to get real hot when there at the output limits.


>One method would be to perhaps wind a few test turns on the core and
>drive it with an AC source. Some math would be required to get the
>values in the ball-park, and then you could simply watch the current
>through the inductor and see if it behaves as it should, or if it
>suddenly rises out of control. For example, say you are applying a
>square wave voltage across the inductor, the current should ramp up
>linearly over time (usually very fast, so an oscilloscope is
>needed). If the core saturates, this linear rise in current will
>take a sharp turn upward. Note what current level this happens at,
>as well as the number of turns on the core and the measured
>inductance of the coil. Plug all that back into the formula i gave
>before and this tells you exactly what flux density you achieved when
>saturation set in.


Excellent idea! That would be perfect for what
I'm doing. :-) I could make a small sample cross
section and wind it with some turns then put a
magnet on it, when the current of the coil goes
up I'll know the core has saturated.
Thanks Steve, that will save a lot of time! ;-)

---- Matt Cortner ----