• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Toroid core

Status
Not open for further replies.

transistor495

Member
Forum Supporter
I've taken a number of toroid cores out of SMPS's used for desktop computers. My questions is how to know that whether they're powdered iron cores or ferrite cores or something else?

I assume those SMPS's are switched at something 15KHz or like that. So they would be just iron cores? They shows conductivity on surface using DMM test. I hope ferrite cores won't conduct. Also I'm aware of that the cores will be polished with non conductive coating. I've removed that before testing.

I want to use them for 10.7MHz FM IF stages and discriminator stages. Is that sufficient for this purpose? Please enlighten me.
 

JimB

Super Moderator
Most Helpful Member
There are more types of ferrite and iron dust used in inductor cores that you can shake a stick at!

At a quick guess, it would be safe to assume that the SMPS toroids would be unusable at 10.7Mhz.

Unidentified toroid core are just that, UROs! (Unidentified Round Objects).

Unless you have equipment to make measurements of inductance and Q (Loss Resistance), you are wasting your time.

How do I know? I have been there, torn my hair out when things that should work did not.

JimB
 

MikeMl

Well-Known Member
Most Helpful Member
Most modern switchers run between 80kHz and 1.5MHz.
 

crutschow

Well-Known Member
Most Helpful Member
I assume those SMPS's are switched at something 15KHz or like that. So they would be just iron cores? They shows conductivity on surface using DMM test. I hope ferrite cores won't conduct. Also I'm aware of that the cores will be polished with non conductive coating. I've removed that before testing.
Ferrites are conductive. They just have a much higher resistance than an iron core.
 

Ubergeek63

Well-Known Member
Ferrites are conductive. They just have a much higher resistance than an iron core.
sure you are not thinking of nickel cores? ferrite, by definition, is ceramic and might as well be an insulator. this is an advantage since it does not require laminations to prevent parasitic currents in the core.

as opposed to some wound and enamaled toroids made of nickel sheet rolled into the toroid form.

dan
 

transistor495

Member
Forum Supporter
After having a look at amidoncorp website, I believe those are not ferrite toroids( almost sure ). So I've to go in search of ferrite ones.
 

Hero999

Banned
In my experience ferrite is conductive, albeit very poorly.

It's fine to treat it as an insulator, except at high voltages.
 

indulis

New Member
Put a ferrite core on a magnet and see what happens... you might reconsider them being an "insulator".
 

transistor495

Member
Forum Supporter
Whether conductive or not I'm too much specific about my application...so I had a look at amidoncorp website and found 67 material toroids might be excellent for my application. Local availability of same spec.s is searching on.
 

Hero999

Banned
Put a ferrite core on a magnet and see what happens... you might reconsider them being an "insulator".
What do you mean?

Something can be magnetic and still be an electrical insulator.
 

indulis

New Member
Something can be magnetic and still be an electrical insulator.
Really... how about an example?

What is true is that not all conductive materials are magnetic i.e. aluminum.
 
Last edited:

Hero999

Banned
Really... how about an example?

What is true is that not all conductive materials are magnetic i.e. aluminum.
You've got me there.

Well there's no strong link between electrical conductivity and magnetism, for example ferrite is a very poor conductor (much worse than most metals) yet it's very magnetic.
 
Status
Not open for further replies.

Latest threads

EE World Online Articles

Loading
Top