How to know whether its ferrite core or iron core in transformer?

[Clarkdale44]

I am quite new in electronics,
I want to make a cfl emergency light and its circuit requires me to have a ferrite core transformer, i have few lying around but not sure whether they have iron core or ferrite core. How to know if its ferrite or iron material?

 

[Inquisitive]

Ferrite is iron.

 

[DerStrom8]

Ferrite is iron.

I think what he was asking is how to know the difference between a solid ferrite core (better for high frequency transformers) and powdered iron (better for chokes and filters).

My answer would be to buy a new core and look at the specs from the manufacturer. Most of the time if you reuse old cores (pretty much the only reason you would want to know how to identify them), they will not work well at all. Trust me, I just wound a few gate drive transformers, which HATE powdered iron cores

 

[jpanhalt]

Here's one answer: https://forum.allaboutcircuits.com/showpost.php?p=388949&postcount=4

John

 

[dr pepper]

Iron transformers esp power ones have iron laminates, dozens of thin metal plates bolted or welded togther.

If the core has a dark smooth finish then its probably iron powder or ferrite, iron powder cores are common for medium freq applications, filter chokes in pc power supplies are often iron powder, they often have a coloured stripe on to denote the material.
There are different types of ferrite too, but unless marked you need special gear to measure the parameters, 80's on tv flyback's are usually ferrite.

To build a cfl driver I'd salvage a ferrite power trans, heat it up with an air gun, take it apart and rewind it, try googling for cfl joule thief driver.

 

[Clarkdale44]

Iron transformers esp power ones have iron laminates, dozens of thin metal plates bolted or welded togther.

If the core has a dark smooth finish then its probably iron powder or ferrite, iron powder cores are common for medium freq applications, filter chokes in pc power supplies are often iron powder, they often have a coloured stripe on to denote the material.
There are different types of ferrite too, but unless marked you need special gear to measure the parameters, 80's on tv flyback's are usually ferrite.

To build a cfl driver I'd salvage a ferrite power trans, heat it up with an air gun, take it apart and rewind it, try googling for cfl joule thief driver.

Yeah, i did, its called Jeanna's light. I tried building it but was unsuccessful. I tried rewinding it many times but still not worked. Maybe my toroid was iron core or was a bit small. I am now thinking of making this one. https://www.instructables.com/id/A-simple-low-voltage-inverter-for-fluorescent-lam/?ALLSTEPS

 

[Clarkdale44]

Ferrite is iron.

If what you say is true then explain this answer.
https://forum.allaboutcircuits.com/showpost.php?p=388949&postcount=4

 

[Inquisitive]

Per Oxford dictionary.

ferrite
Syllabification: fer·rite
Pronunciation: /ˈferīt /
NOUN
1 A ceramic compound consisting of a mixed oxide of iron and one or more other metals. Ferrite has ferrimagnetic properties and is used in high-frequency electrical components such as antennas.

2 Metallurgy A form of pure iron with a body-centered cubic crystal structure, occurring in low-carbon steel.

 

[jpanhalt]

Per Oxford dictionary.

ferrite
Syllabification: fer·rite
Pronunciation: /ˈferīt /
NOUN
1 A ceramic compound consisting of a mixed oxide of iron and one or more other metals. Ferrite has ferrimagnetic properties and is used in high-frequency electrical components such as antennas.

2 Metallurgy A form of pure iron with a body-centered cubic crystal structure, occurring in low-carbon steel.

So why did you depend solely on the metallurgical definition to answer an electronic question? Certainly, the context of the original question indicated the OP used the term ferrite to refer to the ceramic compound.

It may also be interesting to note that the iron used today in transformers is not predominately ferrite, i.e., a body-centered cubic crystalline structure:

John

 

[Inquisitive]

I stand to be corrected. My understanding was as stated.

 

[DerStrom8]

Yeah, i did, its called Jeanna's light. I tried building it but was unsuccessful. I tried rewinding it many times but still not worked. Maybe my toroid was iron core or was a bit small.

My bet is that you used powdered iron, which is horrible at high frequencies. Like I said, you'd be hard-pressed to find a good ferrite core designed for high-frequency transformer applications when you simply take them out of old electronics. You really need to buy one with a high Al value, otherwise it will almost definitely not work.

 

[dr pepper]

Jeannas light is very popular.
Did you try reversing the connections on one of the input coils?
Iron core would probably still work just not as efficient.
I made a 1.5v cfl for a mate who lives on a boat, he's incredibly tight and wont have proper lights, anyway I used a fuji disposeabl camera circuit to light a cfl, only takes a few minutes to get a cfl to light from on eof these, and the o/p is useable.
That link looks as though it'd work.

 

[The Electrician]

If what you say is true then explain this answer.
https://forum.allaboutcircuits.com/showpost.php?p=388949&postcount=4

THE RB must have been joking when he said that. Of course a magnet will stick to ferrite. There wouldn't be any point in using a non-magnetic material as the core of a transformer (unless you really want an "air core" transformer).

It's easy to test. Get a magnet and try it. A magnet will stick to any of the materials commonly used as transformer cores--iron laminations, powdered iron, ferrite, permalloy, etc.

It's not too hard to distinguish powdered iron from ferrite. Take your pocket knife and scrape the material (get under the paint if the material is painted, as powdered iron toroids often are); powdered iron is soft and the blade will scrape off some easily. Ferrite is quite hard and will dull your knife blade.

 

[Clarkdale44]

Jeannas light is very popular.
Did you try reversing the connections on one of the input coils?
Iron core would probably still work just not as efficient.
I made a 1.5v cfl for a mate who lives on a boat, he's incredibly tight and wont have proper lights, anyway I used a fuji disposeabl camera circuit to light a cfl, only takes a few minutes to get a cfl to light from on eof these, and the o/p is useable.
That link looks as though it'd work.

Yes i did, i tried reversing polarity of battery, collector emitter wire as well, CFL didn't even blink at all. I think the problem was i had iron core toroid, i got it from an old smps, its color is yellow.

 

[Clarkdale44]

THE RB must have been joking when he said that. Of course a magnet will stick to ferrite. There wouldn't be any point in using a non-magnetic material as the core of a transformer (unless you really want an "air core" transformer).

It's easy to test. Get a magnet and try it. A magnet will stick to any of the materials commonly used as transformer cores--iron laminations, powdered iron, ferrite, permalloy, etc.

It's not too hard to distinguish powdered iron from ferrite. Take your pocket knife and scrape the material (get under the paint if the material is painted, as powdered iron toroids often are); powdered iron is soft and the blade will scrape off some easily. Ferrite is quite hard and will dull your knife blade.

Alright i will try it out...

 

[DerStrom8]

I think the problem was i had iron core toroid, i got it from an old smps, its color is yellow.

I had a feeling

Those toroids are extremely lossy and do not work well as transformers, especially at higher frequencies. Generally they are used as chokes, and now you can see why. I bet if you hooked an oscilloscope up to the secondary and fed your signal into the primary, you'd see an extremely poor output signal.

 

[alec_t]

You can probably salvage a ferrite toroid from a dead CFL. It's one of the less-likely-to-fail components.

 

[DerStrom8]

This may clear up some things:

There are various types of Ferrite, all of which contain iron. The difference between the type used in transformers and the type used in chokes (i.e. solid Ferrite vs. Iron Powder) is this:

Solid Ferrite: Usually Manganese or nickel, zinc, and iron. Substance is a solid cubic crystalline structure. Best for transformer applications.
Iron Powder: Also usually an alloy, but it is crushed into a powder, which creates millions of air gaps distributed throughout the core. Best for chokes.

Both will generally stick to a magnet, depending on the concentration of iron in the alloy.

Hope this helps.
Regards,
Matt

 

[Clarkdale44]

You can probably salvage a ferrite toroid from a dead CFL. It's one of the less-likely-to-fail components.

Guess what! i have hundreds of them...

 

[Clarkdale44]

This may clear up some things:

There are various types of Ferrite, all of which contain iron. The difference between the type used in transformers and the type used in chokes (i.e. solid Ferrite vs. Iron Powder) is this:

Solid Ferrite: Usually Manganese or nickel, zinc, and iron. Substance is a solid cubic crystalline structure. Best for transformer applications.
Iron Powder: Also usually an alloy, but it is crushed into a powder, which creates millions of air gaps distributed throughout the core. Best for chokes.

Both will generally stick to a magnet, depending on the concentration of iron in the alloy.

Hope this helps.
Regards,
Matt

Thanks for the explanation, I think i found which i am gonna use for my project. Was able to differentiate using that pocket knife trick.