High current ferrite beads.

Even a 10 turn air core coil with 10 uH inductance will give a reactance of >600 ohms at 10 MHz which may be very satisfactory for this purpose. They are designed to be lossy (made of the same ferrite powder used for the permanent magnets) and I do not think that the core saturation is a *real* problem. For example, the permeability is most commonly assumed as a constant (we usually refer this quantity as the initial permeability) whereas in reality it is also a complex quantity that depends on the frequency. At high frequency, the dissipation increases, the effective permeability drops (it may drop by a factor of 100 from 1 MHz to 100MHz; rather significant) and the energy stored in the magnetic field cannot be recovered. See, e.g., **broken link removed**

The story can be rather different for hard ferrites that has a wide hysteresis loop but a significant slope even at the saturation point; in other words, they refuse to get saturated. In the intended use of the OP, the bead was supposed to remove noises (in MHz range) in the input signal in the regulator because the regulator simply cannot respond to fast signals and will simply get heated due to dissipation.

I sure have gotten some food for thought, but just to say look at this:

First off, this looks like one of those beads you saw way more of in the past:
https://www.mouser.se/ProductDetail...=sGAEpiMZZMsuct6UGZJC7Y9vIXAljJDiMQ5I5CmUme4=

And then look at this, its a toroidal core but it is rated such as a ferrite bead with Z at 100MHz...:
https://www.mouser.se/ProductDetail...=sGAEpiMZZMsuct6UGZJC7VqRV5TwGQrxg15p3NqoiSg=

I don't know if these are relevant at this point but I wanted to show them anyway because they seem to differ from most other ferrite product online, mouser has a lot many more of these kind of toroids

Regards

The core from Fair Rite could be used for higher current applications as it has a graph for Gauss vs Oersteds. The core from Murata is meant to be used as a cable suppression device and no information is given for your intended use.

Typically in cable suppression use, the net current is zero as both power and return is in the same cable. You would be on your own to try it and measure it's properties.

OK, simple rules of thumb, if ferrite is hi mu (most is) then the beads/toroids/whatever are designed for CM (common mode) suppression, where the send AND return wires go thru the ferrite, so no net flux in ferrite except for that from common mode currents, where it is very low mu these closed cores are designed for use as a proper inductor (for e.g. iron powder) where they effectively have a distributed gap, and a few turns gives a low to moderate inductance, i.e. it doesn't saturate for low to medium currents...

David_ said:

The hole idea comes from a app note from Linear technology, I watch a film clipp where some of the prominent persons within the company(can't remember he's name)

Click to expand...

The late and great Jim Williams, one of the brightest analog engineers ever, avid Tektronix analog scope collector, and co-founder of Linear Tech.

Here is an ADI appnote on ferrite beads

https://www.analog.com/library/analogDialogue/archives/50-02/ferrite-beads.pdf