Permeability of transformator cores.

[Gunders]

Could somebody help me with this little problem?
I'm just wondering what the permeability of a toroid transformator core is..
I know there are some variation, but I need some realistic numbers to work with.

My plan is to wind a inductor, and I'm going to use a tranformator core as the core for the inductor.
But to calculate the windings I need to know the permeability of the core.

[peranders]

The core is soft iron with a small amount of silicone if I'm not wrong. Take the µr for soft iron, this will be a good start. You could also ask for example www.toroid.se and Mikael Gustafsson. mikael@toroid.se or mikael.gustafsson@toroid.se not sure about the email address though.

[tiroth]

It will depend on the core composition. If you don't know the composition the best way is probably empirical: wind enough turns around the core to some idea of the actual value.

[pinkmouse]

Gunderz

I merged your two threads into one, most people here read several areas so you should still get the answers you require

Now, handing back to the intelligent members....

[Jeff R]

Typical permeabilities can range from 14 to 550, according to my Magnetics Inc. toroid catalog.

This is a very wide range and is fairly useless information for determining windings. As tiroth said, you may simple need to wind a few turns and see what results.

[Circlotron]

If the inductor is for DC like in a power supply filter then you must have an airgap in the magnetic circuit otherwise it will be practically useless for DC. Fine for AC as in a Xover choke though. Lots of inductance for not much turns = low resistance.