How do I know if I need to use a specific core material for an inductor? I need to make a 40 microHenry inductor for our project in school. Our teacher said we can make one using ferrite core, 2 inch length, .5 inch diamter with 120 turns of #20 magnet wire. Unfortunately, we cannot find ferrite core. I saw some articles online about Air-core inductors (using plastic for winding). Can I not use ferrite core for this inductor? Will I have any problem with permeability? Thanks in advance!

 

Welcome to AAC

You can insert a ferrite into an air core one and turn it into a ferrite core one somewhat. Air gap will vary the inductance I think.
In Ferrite core ones, the coil is wound onto the core so it would not be loose.

You teacher gave you the requirements. I suggest you stick with it.

 

You can make a 40uH air cored coil by close winding 240 turns of #20 wire on a 0.5" former. But it sounds like that is not what is required.

 

You can make a 40uH air cored coil by close winding 240 turns of #20 wire on a 0.5" former. But it sounds like that is not what is required.

What do you mean by "it sound like that is not what required"? Thank you!

 

What do you mean by "it sound like that is not what required"? Thank you!

Because you are asked to wind it on a ferrite core.

 

Unfortunately, we cannot find ferrite core.

http://www.amidoncorp.com/
http://www.amidoncorp.com/rods-and-tiles/

Note that you will likewise find winding formulae at the above linked website

FWIW an Fe powder core would likely be a better choice Re: achievement of the desired inductance...

Best regards
HP

 

What do you mean by "it sound like that is not what required"?

I need to make a 40 microHenry inductor for our project in school. Our teacher said we can make one using ferrite core

---Emphasis added---

It is unclear whether the underscored text (above) is a stipulation or merely a suggestion?...

Best regards
HP

 

---Emphasis added---

It is unclear whether the underscored text (above) is a stipulation or merely a suggestion?...

Best regards
HP

Thank you for answering. For me, I think it was more of a suggestion. The only specs that we have to follow is the inductor being 40microHenry. ))) Do you know the difference of air-cored and ferrite-cored conductor?

 

Thank you for answering. For me, I think it was more of a suggestion. The only specs that we have to follow is the inductor being 40microHenry. ))) Do you know the difference of air-cored and ferrite-cored conductor?

The air core inductor will require more turns than one on a ferrite or iron-powder core.

 

Do you know the difference of air-cored and ferrite-cored conductor

A ferrite core will permit achievement of the desired inductance with fewer turns but at the 'cost' of hysteresis losses and liability to saturation - Hence appropriate core selection (i.e. material and cross-section) will properly be with regard to operating frequency and current (respectively)...

Please be advised that toroidal cores offer advantages in the ways of compactness and 'self-shielding'...

Please note that the resource linked in (post #6) features several core forms (including toroids and solenoids) available in a large variety of materials...

Best regards and good luck!
HP

Disclaimer -- I am not, in any way, associated with Amidon! -- That said; It is my strongly held opinion that their policy of comprehensive applications documentation distinguishes them as the 'go to' supplier for new design!

 

A ferrite core will permit achievement of the desired inductance with fewer turns but at the 'cost' of hysteresis losses and liability to saturation - Hence appropriate core selection (i.e. material and cross-section) will properly be with regard to operating frequency and current (respectively)...

Please be advised that toroidal cores offer advantages in the ways of compactness and 'self-shielding'...

Please note that the resource linked in (post #6) features several core forms (including toroids and solenoids) available in a large variety of materials...

Best regards and good luck!
HP

Disclaimer -- I am not, in any way, associated with Amadon! -- That said; It is my strongly held opinion that their policy of comprehensive applications documentation distinguishes them as the 'go to' supplier for new design!

It's Amidon HP, Amidon

http://www.amidoncorp.com/

 

It's Amidon HP, Amidon

http://www.amidoncorp.com/

Corrected! - many thanks for the 'heads up'

Very best regards
HP

 

Corrected! - many thanks for the 'heads up'

Very best regards
HP

'saright. Homophones can be hard to spell correctly from just hearing the word.

 

A ferrite core will permit achievement of the desired inductance with fewer turns but at the 'cost' of hysteresis losses and liability to saturation - Hence appropriate core selection (i.e. material and cross-section) will properly be with regard to operating frequency and current (respectively)...

Please be advised that toroidal cores offer advantages in the ways of compactness and 'self-shielding'...

Please note that the resource linked in (post #6) features several core forms (including toroids and solenoids) available in a large variety of materials...

Best regards and good luck!
HP

Disclaimer -- I am not, in any way, associated with Amidon! -- That said; It is my strongly held opinion that their policy of comprehensive applications documentation distinguishes them as the 'go to' supplier for new design!

Thank you!

 

It's Amidon HP, Amidon

http://www.amidoncorp.com/

Thank you!

 

In all this thread, the TS failed to inform the group as to the use of the inductor (other than "our project"). The type of inductor is very much dependent on the application of the inductor. There are more parameters of an inductor than just the inductance - you need to stipulate all of them.