# Windings on inductor / transformer question

#### late_bloomer

Joined Feb 22, 2017
21
Hello all.

I'm new to this forum, fairly new to electronics.

I have a few questions about making own inductors/transformers..
• When winding an inductor or transformer, does it matter which direction the windings are turning (clockwise/counterclockwise)?
• When turning the windings in one direction and I reach the top, can I continue turning same direction but instead of going up, simply going down (second layer of windings)
• If any, does the number of layers of windings have any effects on signal
I tried looking for these answers, but i could not find anything useful, or I do not know how to search properly, maybe i'm missing certain terminology..

#### JUNELER

Joined Jul 13, 2015
183
Hi,
You want to learn how to do transformer winding. The best idea is to read any books on electrical
regarding the transformer. In that manner it give you clear understanding.GOOGLE IT

#### KeepItSimpleStupid

Joined Mar 4, 2014
3,752
Curl your fingers and point your thumb of the right hand. It's known as the right hand rule. It can tell you the direction of the magnetic when knowing the electric field direction. The primary should wind in the same direction as if the core was turning. Forward or backwards doesn't matter.

The wire should be evenly spaced especially for torroidal cores.

The primary is usually the winding closest to the core and you would like to know the start position of the same direction of the primary. This indicates the phase relationship.

Layers are not as important as uniformity.

#### Marley

Joined Apr 4, 2016
311
When winding an inductor or transformer, does it matter which direction the windings are turning
No but if you have more than 1 winding then the relative directions do matter.

When turning the windings in one direction and I reach the top, can I continue turning same direction but instead of going up, simply going down
Yes, correct continue winding in the same direction but go down instead of up.

If any, does the number of layers of windings have any effects on signal
Depends on the type of transformer or inductor but generally: not much effect.

Try and do a very neat job when winding. Keep all the turns side by side with no gaps. That way the winding space is fully filled. Also, turns that overlap can short out easily. If you have space put a layer of tape between the layers. There is usually an insulating layer between separate windings.

Best thing is to find a scrap transformer, take it apart and see how the professionals do it. An old PC power supply has lots of examples of transformers and inductors inside. Plenty on any trash heap anywhere!

Joined Jul 18, 2013
19,422
When winding identical secondaries that are to be used together you want to keep them matched, this is done by Bi-filar winding, both wound together.
Max.

#### ErnieM

Joined Apr 24, 2011
8,009
To expand, a bi-filar winding may best be made by taking the wire and simply folding it in half, so both wires are wrapped at the same time in close proximity without any twisting together.

#### late_bloomer

Joined Feb 22, 2017
21
• On inductor/transformer the formula 2*pi*f*L calculates lowest inductance, correct?
• On transformer, if primary has (for example) 10mH and secondary has 3.2 mH inductance, how is it determined the max frequency that can be used on said transformer?

#### GopherT

Joined Nov 23, 2012
8,012