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My inclination is to say that ferrite would generally not be a good stator core material on any motor save for something operating at extremely high rpm. Typically, axial flux motor designs are desirable due to their lower rpm torque. While ferrite has relatively high permeability, It suffers from low and fairly severe saturation flux density (0.5T max) relative to electrical steels. The losses are low but, they’re going to be of greater benefit at higher frequencies. A powdered ferrite would solve some of the saturation concerns but, this will drastically reduce the permeability. It’s possible that something like this might be useful as a gap filler around an electrical steel core/winding when mixed into an epoxy. Now, hard ferrites are something that is commonly used in motor rotors. These are the permanent magnet versions of ferrite. Similar in name but, these are different to what we produce.

It should work fine for snap-its. The permeability might read a little low due to the small air-gap present.

Good idea @kronos4993- it can now be found in the description of the video!

Ask and you shall receive!!

we publish lotsof loss information... What sort of format would be useful to you?

Short answer... Yes, power handling goes up with frequency to a point from the perspective of the core. The limitation in power handling on a ferrite core (and most other magnetic materials) is going to be from core losses (heat generation). These core losses are a function of the flux density in the core. With all else being equal, As the frequency rises, the flux density will drop. Now the core losses for a material will also rise for a given flux density as frequency increases. Each type of ferrite material is going to have some frequency where it is peak power handling. Performance factor is a good metric for comparing in this regard. From the perspective of the overall device, the conductor is going to lose current capacity as frequency increases beyond a certain point.

We would love to have part number markings on all our products, but unfortunately its cost prohibitive and not something our customers value enough to pay extra for. Our engineering kits you will find have part numbers on the parts since it is a sampling of our products.

@@FairRiteProductsCorp thanks for the prompt reply

Our owner and creator loved a good pun and we still do at Fair-Rite 😀

31 material. At 30MHz, they’ll be similar but, 31 should be superior below that due to the higher permeability.

That'll work for ETD or EE core sets as well! The calculation for the cross sectional area and magnetic path length are a little different but, the concept is the same. One thing to be cautious of is the air gap in cores like this. If the surfaces are well finished, this can be negligible. If the surfaces are uneven or rough, this can skew the inductance value very low compared to what the material perm would otherwise be.

One trick would be to use several smaller cores stacked together or in parallel. Lower cross-section cores will typically provide lower losses over a wider range of frequencies (to a point) but, they cannot handle the same sort of flux density as a large core. The ideal core would be something like a long tube shape. Thin walls but, high length the get the cross section number back up. A stack of small cores can be used for a similar effect.

They definitely use geometric tricks to manipulate and dissipate the fields that hit the walls. The ferrites in these are generally just flat absorbers behind the e field absorber foam )typically where the fun geometries come in. In ferrites, we usually talk about dimensional resonance in the sense of standing wave generation inside the magnetic cross section. This is still an area of a lot of research to better understand but, the effect seems somewhat similar to skin effect in conductors.

In most of our engineering kits we do label the cores, or at least color code dot them with the material!

Send your request to ferrites@fair-rite.com and we can send that to you!

Can you provide an electronic copy for download?

@@amham48 Unfortunately as of now we do not distribute the poster electronically. We will make an announcement if and when that is available 🙂

@@FairRiteProductsCorp I would love to have one of those posters for our electronics lab as well, if that's possible! Also, really appreciate your podcast series, and I like that you aren't taking yourself too seriously and can joke around as well, looks like you're having fun working, and I wish more workplaces would show that! ;)

@@larspetersson7168 Thank you!! Email ferrites@fair-rite.com and we can get you a poster sent asap and a Signal Solution Kit if you do not have one already!

Typically the saturation characteristics will be slightly softer. It depends a lot on how well they are made. The tighter the tolerances and the flatter the mating surfaces, the more they will just act like a solid core.

My knee jerk answer not being a transformer designer is that they can be very similar. The difference will be in how they are wound. Toroids have the ability to be sector wound or with overlapping primary and secondary windings whereas, multi-aperture (also known as binocular or balun) cores are really only able to be wound with "stacked" windings.

I've only ever seen 6 aperture cores used in suppression though, I suppose you could make some unusual transformers out of them. A 6 aperture core could be useful for something like a matrix transformer.

52 or 61 material should be the best choices. Generally, you want to select the material that has the highest permeability at your start frequency (12MHz in this case). I mentioned 61 incase the power levels are higher. 61 won't provide as good coupling as 52 but, it will be quite a bit lower loss.

Differential-mode noise is generally not as common as common-mode noise (pun intended). Often it is as simple as there only being one conductor present to "pick up" radiated noise from something. Having just a single conductor out in the open or spread far away from others isn't usually the norm in most electronics. In the context of on a circuit board, differential mode noise will be seen more frequently. Important to note, that differential mode ferrites will suppress differential and common-mode noise. A common-mode configuration will only suppress common-mode noise.-Mike

@@FairRiteProductsCorp Thanks. True, in typical harness configuration, you have multiple wires, and maybe one wire has common mode emissions on it, but I guess that noise will couple onto the other adjacent wires in that harness bundle. How could you identify common mode on that single wire ? Use a current clamp and analyzer? You could save money buying a smaller ferrite for that one wire than buying a larger ferrite to go over the whole harness. But I've never seen that solution before.

@@brucetouzel6484 Cores used in differential mode (single wire) will suppress both common and differential mode noise. The thing with using a core in differential mode is that the primary signal "sees" it. You have to make sure the core isn't adding significant impedance to the thing you DON'T want to suppress. The other thing that needs to be considered in differential mode is the current. Too much and the core saturates and provides no impedance. Smaller diameter cores will require less current to saturate. Differential noise would be most easily measured by checking both lines independently and together. If it shows up on either line independently but, not together, That'll be differential mode noise.

We will be covering this in a video coming soon!

We will be covering this in a video coming soon!

From an electrical standpoint, there is no difference between using a toroid and a multi-aperture core. In some cases, especially when operating QRP, the smaller form factor of a multi-ap core is desirable from a convenience standpoint.

So, if the toroid and the snap-it (the ferrite bit inside) are the same size, the impedance would be almost the same. Toroid would be very slightly higher due to not having a gap. Multiple turns through either would have the same effect of Ω*N^2 at lower frequencies