question about computer power supply torroid?

[samy555]

Hi
The following image shows a part of a PC power supply, Where clearly shows a torroid.

It is yellow

My question is how can I use that torroid to make a 1.2 mH coil?
please give me the formula of calculation and in what frequecy band it can be used?
thanks

 

[yura717]

https://www.ehow.com/how_8293803_calculate-inductance-ferrite-inductor.html

 

[samy555]

https://www.ehow.com/how_8293803_calculate-inductance-ferrite-inductor.html

Thank you, but I have not an inductance meter

 

[bigdogguru]

You might find the follow of interest:

Approximate Inductance of a Toroid

TOROID FORMULAS

How to Calculate the Inductance of a Toroidal Transformer


Of course, you also have the option of unwinding the current configuration and using the toroid core, rewinding it meet the required specifications.


BigDog

 

[szhighstar]

First please advise which appliaction the inductor will be, storage emergy inductor or PFC inductor or filter or a transformer, from your picture, there are two colour of wire in the toroidal, parallel wire wouned or two winding?

Second you can select core according to application,if it is PFC inductor, select Fe-Si-Al or Powder iron or MPP or Fe-Si or high Flux material, if it is filter, select powder iron or MPP or Sendust, if it is transformer, select Mn-Zn power core or MPP or high Flux or power iron.

Thrid you can select core size according to L*I*I, then you can design turns and diameter of wire.

 

[samy555]

OK Ok Ok
I'll ask another question:
Is it possible that those tow inductors in the picture are 1.2mH and 4mH?

Looking at the picture, I think the number of laps in each inductor ranges from 80 to 100 turns

 

[bigdogguru]

Is it possible that those tow inductors in the picture are 1.2mH and 4mH?

It is possible.

However, without physically measuring the dimensions, counting the windings and using the formulas to calculate the inductance, you cannot be certain.

Do you have possession of the board in the photo?


BigDog

 

[samy555]

No I do't have possession of the board in the photo, but I am sure that the number of turns range from 80 to 100
I look at this, from: https://www.electronics-tutorials.com/basics/toroids.htm
TYPE COLOR AL Freq. Range

T50-26 Yel-Wh 320uH power freq.
T50-3 Gray 175 50 Khz to 500 Khz
T50-1 Blue 100 500 Khz to 5 Mhz
T50-2 Red 57 2 Mhz to 30 Mhz
T50-6 Yellow 47 10 to 50 Mhz
T50-10 Black 32 30 to 100 Mhz

If AL = 320 , I have to wound 350 turns to get 4mH, no one of the inductors in the above photo seem to be 350 turns???

 

[BradtheRad]

For a rough comparison you can do an internet search for a 1 mH coil. Click Images. Compare the pictures with your coil.

 

[szhighstar]

Hi Samy, from picture, two are commn mode choke(two windings), however see from schematic, two are only single winding filters.

- - - Updated - - -

Hi Samy, from picture, two are commn mode choke(two windings), however see from schematic, two are only single winding filters.

 

[rohitkhanna]

No I do't have possession of the board in the photo, but I am sure that the number of turns range from 80 to 100
I look at this, from: https://www.electronics-tutorials.com/basics/toroids.htm
TYPE COLOR AL Freq. Range

T50-26 Yel-Wh 320uH power freq.
T50-3 Gray 175 50 Khz to 500 Khz
T50-1 Blue 100 500 Khz to 5 Mhz
T50-2 Red 57 2 Mhz to 30 Mhz
T50-6 Yellow 47 10 to 50 Mhz
T50-10 Black 32 30 to 100 Mhz

If AL = 320 , I have to wound 350 turns to get 4mH, no one of the inductors in the above photo seem to be 350 turns???

your AL values seem to be 10x of what are usually quoted for T50-x mix toroids
Do re-check your units & formulas

cheers!

 

[samy555]

your AL values seem to be 10x of what are usually quoted for T50-x mix toroids
Do re-check your units & formulas

cheers!

Are you sure?
if yes your answer was the best
thanks

 

[krp]

This calculator;

**broken link removed**

is the best one I know; download it and experiment.

Toroid materials used in power supplies are usually high-ui (in the range of hundreds to tens of thousands)/low-frequency ferrite types. They are not colour-coded and are all a grey/black colour.

This makes unknown ferrites very difficult to identify; there are ways to narrow the possiblities down but, for certainty, a VNA or other complex-impedance measuring instrument is required.

Iron-powder materials are not common in power supplies; they are usually used in high-frequency/RF applications. The different materials are identified by colour; red, yellow etc as you will see in the calculator I recommended. Their ui is low so hundreds of turns would be required on most of them to achieve inductances in the mH range.

The exception is #26 material which is used for chokes and filters; it is colour-coded yellow & white. Its ui (75) is high for an iron material but very low compared to ferrite materials so it will require a lot of turns to produce inductances in the mH range.

If the toroid you have is clearly yellow & white it is #26; you can apply the calculator to design your inductors.

If you cannot identify it you will require instruments to do so.

I don't think it good practice to use unknown ferrite materials in any but the most uncritical applications; known-material toroids are not usually expensive (Google W8DIZ for his shop) and reduce uncertainty.

I buy ferrites in quantity and, immediately upon receipt, mark them with coloured dots in a simple code for each material and store them in separate bags for each size & type.

 

[rohitkhanna]

Are you sure?
if yes your answer was the best
thanks

Yes i'm sure. I wind my own toroids regularly. Of course - like i wrote earlier - your formula must match the units naturally.

L (nH) = AL * N^2

So for example 10 turns on T50-2 will yield L = 570nH, (not 5.7u using your AL = 57nH/n2)
AL for T50-2 is usually 4.9 (from several sources....here's one **broken link removed**).

HOWEVER the AL value ALSO depends on the core size to some extent, so make sure you lookup the size parameter properly as well after measuring the cores in your pic!!
TXX-YY where XX is an indicator of size, and YY is the material mix number.

Anyhow... do re-check units & formulas & re-calculate your numbers.

cheers!

- - - Updated - - -

This calculator;

**broken link removed**

is the best one I know; download it and experiment.
......

Thanks... that IS useful

 

[krp]

You're welcome.

I don't understand the reference to a yellow toroid in the OP's first post; I can't make-out any yellow.

The smaller toroid in his second photo seems to have yellow insulating material wrapped around it to prevent sharp edges scratching the enamel wire insulation; it is not yellow-painted as a #6 iron-powder toroid would be.

I'm convinced that none of the toroids in the photos are iron-powder; even #26 material requires around 200 turns on those-sized toroids to achieve 1.2 mH.

To achieve inductances in the 1.5/4.0 mH range you require ferrite, not iron-powder. Ferrites have ui in the range of thousands whereas iron-powder has ui in the region of unity or a couple of tens.

At a wild guess, the toroids in the photos might be F or J ferrite material which are common in power supplies.

They have quite different ui values; an inductor wound on one will have a very different inductance to an identical inductor wound on the other.

If a 1.2 mH (or any other value) inductor is required by the OP, the only sound method is to design it using a calculator like the one I provided, taking into account the application and the frequency, buy a toroid of the correct size & material from a reputable supplier and wind-on the calculated number of turns.

Even then there will be a variation from the design inductance but, for power supply/filter application, it won't matter.

An unknown-material toroid can only be used if its AL can be determined; that requires an inductance meter and the OP has told us that he does not have one.

Even if he did, it would not determine the useful frequency range of the material although, if it came from a power supply it might be assumed to be suitable for power-supply frequencies.