Which Color Toroid and Ferrite material is best?

[gary350]

I bought some Green 10mm x 25mm Ferrite Toroids from China.

1 Green toroid with 11 turns of wire on makes a .5 mh choke.

2 Green toroids taped together with 11 turns of wire makes a 1 mh choke.

4 Green toroides taped together with 11 turns of wire makes 1.8 mh choke.

1 TV toroid white snap together plastic case with 37 turns of wire same physically size as 1 Green toroids makes a 8 mh choke.

2 black natural color toroids taped together 4 times larger than 1 Green toroids with 11 turns of wire mades a .2 mh. Larger is NOT better.

I am looking for toroids in several places and not finding much. I bought toroids from Jameco in the past but they no longer have toroids listed. Ebay has some but there is NO date about the toroids. I checked several of the parts companies listed on this forum not finding many toroids. One place called West Florida Components has a small .8 inch toroid that says it his high flux. I'm not finding pre made chokes either.

Will higher flux make a higher mh choke?

Any suggestions where and what to buy I want to make a 26 mh choke?

 

[moty22]

deleted

 

[gary350]

I need a 26mh choke rated for 60KHz.

Defination of permeability is a material that passes water. Low permeability will be a dense material. High permeability will be a softer material.

Deffination of low permeability. Used widely in power transformers, current transducers, instrument transformers, inductors, chokes, ballasts, voltage stabilizers and regulators, welding transformers, broad band transformers, filters, etc.

I have no clue what I am looking for?

$10 each for a 1.9" diameter toroid seems expensive.

 

[KeepItSimpleStupid]

77 material should work for you. See: https://www.fair-rite.com/newfair/materials.htm and https://www.cwsbytemark.com to purchase.

Permeability has a wide tolerance and I suspect it's more predictable per batch/lot.

 

[Mosaic]

Is this post related to this one?
https://www.electro-tech-online.com/threads/power-supply-capacitors-keep-going-up-in-smoke.143684/

If so it would be better not to have a lot of independent threads.

 

[dr pepper]

The 3 important factors for material are flux density, working freq and permeability.
Iron powder cores give a high inducatnce per turn but have a low operating freq and a soft saturation curve, N87 or 97 power ferrite has a high flux density but a lower operating freq.
Depends what you want to do, what are you making.

 

[gary350]

How does a person know these 3 things, flux density, working freq and permeability???????????

How does a person know the value of each of these 3 things for the project they are working on???????

Sellers have no information about the toroids.

I am not finding any helpful educational toroid/choke information either?

An online choke calculator might be helpful but I would need to know things like toroid material, size, etc.

I assume I wind the toroid with the wire size I need for the current in the circuit. I assume I wind as many turns as I need to get the 26mh I want testing it with the meter as I go to make sure I have 26mh. Now how do I know what this choke will do? Will it run all day for 8 hours and not over heat or does it need a cooling fan? Will it block 60KHz and pass 15 VDC????? IT sounds like a Try again, Guess again project to me.

 

[dr pepper]

I see, sounds like your between a rock and a hard place.

 

[chemelec]

11 Turns is a Small Sample for these Calculations.
BUT If 11 Turns = 0.5 mH

To Find AL Value

1000/ 11 turns =90.9090909
90.9090909 * 90.9090909 (Squared) = 8264.45
* L in mh = AL Value
8264.45 *.5 = 4132
AL Value = 4132

To Find the Turns required to get 26 mH, knowing this AL Value in mH.

26 / 4132 = .0062923
Square Root of .0062925 =.079324

.079324 * 26 = 79.32 Turns <THIS IS WRONG>
SHOULD BE: .079324 * 1000 = 79.324

So 79.32 Turns on that Same Torroid will give you a 26 mH Choke.

But A Better Torroid would be a 77 or 78 Material.
And it should be Fairly large to use Large Wire as needed.

 

[KeepItSimpleStupid]

The cws link I posted has data. They also sell small quantities. Core material is universal.

BUT with 30% variability with permeability it makes you wonder. My guess, is one makes one, tweaks it and then makes a bunch using the new recipe for the same batch.

 

[chemelec]

"Fair-Rite Products Corp". and "Magnetics Technologies" as well as Many others, Produce a Variety of Torroid coils with Know AL Values.
These Companies do Not usually sell direct to the Public.

These Torroids can be Purchased from Dexter Magnetics, BUT ONLY IN LARGER QUANTITIES.

However If you have a Specific PART Number, they can possibly tell you Who will sell you JUST ONE.

First you need to Determine What Size of Wire your going to use.
And Knowing it will require Quite a Few Turns, try to Determine SIZE of core you need.

I have all these Manufacturers Catalogues, so than I can possibly help you.

I Seldom use Torroids.
But I Do have some Larger EE" Cores that you could use to make that Choke Coil.

 

[gary350]

11 Turns is a Small Sample for these Calculations.
BUT If 11 Turns = 0.5 mH

To Find AL Value

1000/ 11 turns =90.9090909
90.9090909 * 90.9090909 (Squared) = 8264.45
* L in mh = AL Value
8264.45 *.5 = 4132
AL Value = 4132

To Find the Turns required to get 26 mH, knowing this AL Value in mH.

26 / 4132 = .0062923
Square Root of .0062925 =.079324
.079324 * 26 = 79.32 Turns
So 79.32 Turns on that Same Torroid will give you a 26 mH Choke.

But A Better Torroid would be a 77 or 78 Material.
And it should be Fairly large to use Large Wire as needed.

I am trying to use your example to work a problem but I keep getting crazy answeres.

Does this symbol * mean multiply?

If so math appears to be wrong.

You have .079324 * 26 = 79.32 Turns

I get .079324 times 26 = 2.06

Yes the 77 material looks like a good choice. OK I see what we are doing here. This is a way to calculate the number of turns without experementing to figure it out. This is good to determine the toroid size so I know it will be large enough for the required number of turns. Now what about wire size? Assume 15 amps in the circuit according to the online wire charge = #14 copper wire. Wire charts are for 60Hz but what will 60 KHz do to the wire on a toroid? Power suppy is 15 VDC and my meter reads 8.4 amps but RF voltage is 70 VAC at 60 KHz.

 

[chemelec]

Sorry Screwed up.

SEE Correction in POST 9
SHOULD BE: .079324 * 1000 = 79.324

 

[gary350]

Learing Experement.

I used 42 enamel coated #30 copper wires. I twisted them a little just so they would be easy to put through the 9 toroids I have taped together. I have 12 turns of wire. Cross sectional area of 42 wires is = to 14 gauge copper wire rated for 15 amps. This is a learning experement to see if larger wire can handle more current and not get hot and also to learn the mh value of the coil.

A 2 minute run at full power and the large choke was still room temperature. This is exactly what I wanted to know. Maybe #14 solid wire would get warm because it is less surface area and less cooling than 42 seperate wires.

2 toroids with 11 turns of wire = 1 uh so 9 toroids with 11 turns of wire should be 4.5 mh. I have 12 turns of wire = 6.3 mh. I know 1 extra turn did not increase it by almost 2 mh. Does the increase of almost 2mh have something to do with using higher current wire or using 42 wires?

Almost forgot to mention wire resistance of the 42 wire 6.3 mh choke = .3 ohms. Wire resistance of the 8 mh choke = .4 ohms.

Look at the toroid mounted to the induction heater circuit with 38 turns of #18 enamel coated copper wire wound on 1 toroid same material. It is 8 mh and gets too hot to touch after 2 minutes. If I dont turn this off at 2 minutes the choke starts to smoke.

**broken link removed**

**broken link removed**

 

[chemelec]

Well I don't have enough info to give you an answer.

But I Suspect that your torroid is too small and is probably going into saturation.
More Turns Won't fix that.

I am not even sure What type of Torroid you have or what material it is made of?
Torroids are made for many different applications.

 

[Honduras]

11 Turns is a Small Sample for these Calculations.
BUT If 11 Turns = 0.5 mH

To Find AL Value

1000/ 11 turns =90.9090909
90.9090909 * 90.9090909 (Squared) = 8264.45
* L in mh = AL Value
8264.45 *.5 = 4132
AL Value = 4132

To Find the Turns required to get 26 mH, knowing this AL Value in mH.

26 / 4132 = .0062923
Square Root of .0062925 =.079324

.079324 * 26 = 79.32 Turns <THIS IS WRONG>
SHOULD BE: .079324 * 1000 = 79.324

So 79.32 Turns on that Same Torroid will give you a 26 mH Choke.

But A Better Torroid would be a 77 or 78 Material.
And it should be Fairly large to use Large Wire as needed.

Very good post.

I would like to add what little I know about toroids, or think I know.

1. The color of the toroid indicates the material it is made from, thus permeability, etc. Basically toroids are poorly marked. The colors are not standardized between manufacturers. They usually have no markings at all. If you buy a toroid with no manufacturers markings on the package, plan to spend some time finding out what it is for.

2. The size of the toroid ring determines the number of turns, and the size of wire that can be wound on them. It also determines the saturability of the toroid. Again, as I understand it, the a toroid is a field device. The field builds up from the outer surface of the coil to the inner. A point is reached where there is no capacity in the toroid for a larger field. As I understand it, this is the saturation point. The larger the cross sectional area of the toroid, the more field it can accept.

3. When winding a core, try to keep the number of turns to a reasonable number. You don't want a tiny toroid with 47 layers of wire wrapped on it. As I understand it, moving the windings away from the toroid, as multiple layers would, can affect the value of inductor.

4. Use double sided tape between the toroid and first winding, and between each layer. It makes it easier, but not easy, to keep the turns in place.

 

[MrAl]

Hello there,

If there is any DC current in the winding that could easily lower the inductance that you see when you only have an AC current. This means it saturates easier and steps have to be taken to minimize that.

So the obvious question is, does the application you intend to use this for have any DC current?

 

[Honduras]

Hello there,

If there is any DC current in the winding that could easily lower the inductance that you see when you only have an AC current. This means it saturates easier and steps have to be taken to minimize that.

So the obvious question is, does the application you intend to use this for have any DC current?

As I understand it, DC passes through an inductor with no impedance except for the resistance from the wire.

DC is not involved in the formula for inductive reactance. Only AC frequency and inductance.

 

[chemelec]

I suspect it is probably related to a few Supplier, Such as Amidon and a few others

Here is what I found on the Internet.

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

All the Torroids I have ordered have been their Noatual Color.
Other than a few I bought from Surplus Suppliers.
(A Few Red ad Blue ones.)

 

[Honduras]

I suspect it is probably related to a few Supplier, Such as Amidon and a few others

Here is what I found on the Internet.

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

All the Torroids I have ordered have been their Noatual Color.
Other than a few I bought from Surplus Suppliers.
(A Few Red ad Blue ones.)

TYVM. Amidon is a good supplier, and they have good design notes, etc.

Unfortunately, I have about a pound of International Orange Toroids. So I think there may be more to it than that.