Ferrite(s)

[T4P]

Okay... dropped one 
Can i just use super glue but will it not be able to permeate to the mended other side and not have a complete magnetic loop?

[SeanB]

It will work provide you can get the parts apart to get them all stuck together. I have used 2 part epoxy as well.

[T4P]

It will work provide you can get the parts apart to get them all stuck together. I have used 2 part epoxy as well.

Apart?... Well the ferrites can go back in 1 piece i'll try super glue first, if not 2 part epoxy

[Hypernova]

The smaller the gap the smaller the effects. If you take apart small transformers they use 2 ferrite E cores glued together so that should tell you how much a flush air gap matters.

Can you post a pic?

[free_electron]

hold it !
Get another piece of ferrite and grind it into ferrite dust  (use patented widlarizing technique) . Blend that in 2-compound epoxy and use that to repair the broken one.

[T4P]

[Gall]

Ferrite can be glued but the glue will act as a gap (a gapped ferrite core).

To minimize the gap, try mixing the glue with ferrite powder. be sure to make the glue layer as thin as possible. I also recommend to measure actual inductance after winding and trim it by changing number of turns. Most likely you'll have to add turns so don't cut the wire too short too early.

[T4P]

These were intended as "ferrite beads" but not really, it had the wires literally looped around the ferrite core so yeah it's an inductor core
If it requires some ferrite dust ... i'd rather keep this one aside ...
I'll go grab some smaller ferrites and grind it ... s*** grinding, blender?

[madires]

Hi!

As Gall already wrote, the glued ferrite will become a gapped ferrite toroid. That changes it's physical properties completely. You may use it for a DC-DC converter now (instead of an iron powder toroid) as long as you don't drive it into saturation.

Best regards,
 madires

[Gall]

Not so strong. A gapped toroid may be used for almost any purpose. Just its A_L will be lower. If inductance does not matter, a glue with ferrite powder would be just fine since it gives almost no gap.

Remember, ferrite is made of powder and has tiny gaps everywhere.

[madires]

Hi Gall!

Not so strong. A gapped toroid may be used for almost any purpose. Just its A_L will be lower. If inductance does not matter, a glue with ferrite powder would be just fine since it gives almost no gap.

Remember, ferrite is made of powder and has tiny gaps everywhere.

It's little bit more complicated :-) Both types are made of powder. Ferrites are sintered, grinded and pressed. Iron powder cores (there are also other powder variants) are grinded, mixed with glue and pressed. The glue causes the distributed air gap. And that distributed air gap causes the ability to store more energy. Ferrites don't have such (large) air gaps. Therefor a (closed) ferrite toroid can't store as much energy as an iron powder one. But if you cut the ferrite toroid you'll get a nice air gap :-)

Of course, you can use what ever type you like. But choosing the optimal type for your circuit helps a lot. It's not just the A_L you'll have to consider.

For DC-DC converters one needs an inductor with a high storage capacity for energy. If you want to support a wide range of input voltages you would drive a gapped ferrite toroid quite fast into saturation. That won't happen as fast with an iron powder one. But the iron powder toroid will require more windings for the same inductance.

Would you use a gapped ferrite toroid for a common mode choke?

Another example. If a HAM radio operator chooses the wrong toroid to build a balun for his 1kW RF transmitter the toroid will become really hot.

Best regards,
 madires