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How to wind toroidal coils?

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carpenter

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I need to wind the toroidal coil
T130 ironpowder 7 theard, current 2A, frequency 15MHz

My first choice and practically proven solution is use magnet wire 1x1,2mm
+ simple solution
+ mechnically stable
+ the wire holds well on the toroid
- higher AC resistance (Skin Effect Depth on 15MHz 17um)

second option
Use 4x0,7 wire,
+ the resistance drops to half
- I do not know how far the parameters will worsen (proximity effect etc...

third option
use RF litz wire 120x0,1mm
+ low resistnce
- soft and so worse hold on the toroid

I do not know whether other losses will outweigh the savings on DC losses and higher coil costs
Do you have any practical examiners, what is worth it?
 

not sure i understand the question

I need to wind the toroidal coil
T130 ironpowder 7 theard, current 2A, frequency 15MHz

what is "7 thread"?

My first choice and practically proven solution is use magnet wire 1x1,2mm
+ simple solution
+ mechnically stable
+ the wire holds well on the toroid
- higher AC resistance (Skin Effect Depth on 15MHz 17um)

sorry, not familiar with this notation - what does
"1x1,2 mm"
mean?

second option
Use 4x0,7 wire,
+ the resistance drops to half
- I do not know how far the parameters will worsen (proximity effect etc...
does 4x0,7 wire mean 4 aught wire? AWG? that's huge and usually for high currents?

third option
use RF litz wire 120x0,1mm
+ low resistnce
- soft and so worse hold on the toroid
litz makes the most sense

I do not know whether other losses will outweigh the savings on DC losses and higher coil costs
Do you have any practical examiners, what is worth it?

every choice has its upside and its downside
you need to decide where you want the heat - wire or core?
which is easier to cool?
 

He means 7 turns, i.e. the wire is threaded 7 times thru the toroid ...

1 x 1.2mm dia is just that, 1 wire, 1.2mm dia

ditto for 4x0,7, this means 4 wires @ 0.7mm dia each

all fairly common power electronics lingo ...

- - - Updated - - -

for 2 amps, small section copper tube works well ...
 

silly me
commas are decimal points and decimal points are comas
 

In my country (EU) continental Europe, ISO standard applies and decimal comma is , (Pi is 3,1415 not 3.1415).
As you may have noticed English is not my native language and in my native language is on coils turns and thread the same expression. In English, I try to use a turns for coils , but when writing the post I solved engineering stuff and the metric thread is thread.

Specifically
Here is a photo of coils with 1.2mm wire
One picture per thousand words

why do I ask at all?
Basically, we have 4 coils
wire length 4x25cm = 1m
Current 2A frequency 15MHz

When the skin effect is taken into account, there will be AC resistance
268mOhm for 1m 1,2mm wire because Skin Effect Depth is only 16,8um
for 4x 0,7mm 464mOhm / 4 =116mOhm
for 120x0,1mm 3742mOhm/ 120 = 31mOhm

Logical clear, there is nothing to solve, but
-the wire is strong, holds well on the toroid (see pic) , stranded wire (120x0,1) it is soft and flexible will not hold well on the toroid this will worsen the coil properties
- Proximity effect applies to multiple conductors somehow it will worsen the coil properties
- RF litz wire 120x0,1 is about 5 times more expensive than 1.2mm wire

I just don't know what to use as optimal solution.

toroids.jpg
 

optimal solution is either litz or tape type copper - e.g. 0.1mm thick ribbon - insulated, 6mm wide - this has more "skin" to carry AC currents ...
 

Copper tape, for sure.
For a given cross-sectional area, its thickness is significantly thinner.

It may not hold as well to the core as plain round wire, however.
 

that's what tape is for ...

- - - Updated - - -

e.g. kapton, polyester ...
 

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