Ferrites

Just buy U cores. They often come in pairs, meaning you get two for one :-)

They sell small quantities and in the past my experience has been good:

Make sure you buy the right material for the frequency range of your choice.

If you need a gap for a "C" (aka "U") shape, the only way is to use some thin tape, thin plastic or thin paper.

Its the type on the left of the image in this link that Im interested in procuring -

Do they essentially act the same as the U-cores you have mentioned above?

Thanks

David

Gapped ferrite toroids are readily available, since they are used for a number current and magnetic field sensing applications and occasionally to build energy storing inductors. You may want to specify 'no fill material' in the gap. Or, you can make your own, using a tile-cutting saw or other diamond blade. The material is brittle, so support it well during cutting. It seems to me that the last time I had need, I got them from Elna:

Paul Mathews

And don't try this on a tile cutting saw with a blade that was already used for a few hundred sqft of Italian porcelain. Speaking from experience here ...

BTW, in the US the MadDog 225 blades are really good but a 7-1/4 incher will set you back almost 50 bucks. Worth it though.

This image is labelled 'iron core'. This is for a good reason, if you intend to experiment with electromagnets. A material with a high DC saturation flux density (ie not ferrite) allows for larger magnetic fields to be created in the gap.

The structure is a tape-wound core that is cut after impregnation, but the same effect can be created using Uor I laminationsm as long as the only gap present in the circuit is where you want it.

UI shapes start on page 62 here

C cores and cut cores

RL