Where to get a ferrite core?

Question

I'm going to try making a Joule Thief (modifications planned if that works) but where do I find a "ferrite core" for winding the inductor? I know RadioShack has large ones but I mean something like dime-size or smaller...

Could I use a iron nail, bent & ground into a circle?

Can I get a ferrite choke and just cut/drill it into a donut shape?

Answer 1

try: http://www.globalsources.com/manufacture...

Ferrite cores have been used since the sixties to my knowledge. You should be able to find them in almost any size you'd like.

Best wishes

Answer 2

This company manufacters ferrite cores of all sizes.  Check their distributors list for availability of the size that you want.  For a small number of cores you can probably just request samples for free.

http://www.ferroxcube.com/

A piece of iron in a circle would not work except at low < 60Hz frequency and even then would work very poorly.

It will be important to know what frequency and current you need to handle.  If the frequency is low then an audio transformer may work for what you need.

Ferrite cores typically are used for 10kHz and up.  Laminated materials, such as AC transformers would be used for lower frequencies.

You can also salvage cores from broken equipment.  For example open a bad computer power supply or computer PC board and they have ferrite cores that you can remove.