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Does it matter how a coil is wound? Answered

Hi everyone,
Take a look at the illustration attached.  Is there any real difference in values between the four winding types?

*** Assuming same core, same wire gauge and same number of windings on all 4 primaries, and all 4 secondaries ***

A) Both primary and secondary are wound TOGETHER.
B) primary is wound first, then secondary wound ON TOP.
C) Primary and secondary are wound at OPPOSITE SIDES of the core .
D) Primary and secondary are wound next to each other on the SAME SIDE of the core.

Note that figure in D it seems like the wires are thinner, but I assure you, that's an optical illusion, and the gauge is the same in all 4 figures :-p

Again, the question is whether the 4 coils would act the same in a circuit, or is there a difference in values between them?



Best Answer 5 years ago

Frequency, voltage, laminating, dimensions, iron grain orientation and
other variables in addition to winding placement affect transformer performance.

A is fine for ;
  • Close coupled signals
  • Usually called bifilar winding
  • Low parasitic inductance
  • Military pricing

B is fine for ;
  • Easy to build
  • Low cost power transformers
  • Radio Shack

C is fine for ;
  • High voltage separation
  • Tesla spark devices
  • Magnetic amplifiers
  • Low mutual inductance
  • Toroid construction

D is fine for ;
  • IF intermediate frequencies
  • Better power transformers
  • Moderate voltage separation
  • Double bobbin applications


Notice that you can fit a greater number of turns into C for the same size core.


Wow thats way more tech than I thought it would be.
I assumed A was the best for everything.
Is this stuff illustrated in any existing instructables?

I started in vocational HS class and still learning.
Maybe some one your age has web pointers.

Here is an interesting factoid on B :

The Primary in most transformers is a small AWG thin diameter
red wire and wound first.
The Secondary is a heavier gauge thicker green wire diameter
because it  carries more AC current on the outside of the red ..

This is done to protect the fine red wire coil from being damaged
in rough handling shipping etc, by using the stronger green wire
as a mechanical shield !


All 4 will behave differently. Not only is the way each coil wound effecting things but also how many turns each coil has. Lets not forget that the diameter of wire used on each coil will have a big effect on how the transformer behaves.

And the DC Copper or Aluminum Resistance !

In some circuits, it makes a huge difference. In some, no. In any system where you want minimal interwinding capacitance for example A and B are very bad. For the highest coupling efficiency though, A and B are good.