EMRFD Message Archive 11710

Message Date From Subject
11710 2015-10-01 00:35:20 rodwall1234 Squeeze More Performance Out of Toroidal Inductors...

Hi all,

Think it was Kerry who posted the following link, thanks Kerry.


It shows a method on how to get more turns onto a toroid by deforming the wire into a wedge shape. But still keeping the wire cross section area large.

Forming the wire into a wedge shape looks like it maybe a problem for home builders.

I was wondering if you could get the same results by winding two wires in parallel. Wires that maybe had half the diameter of the original wire. And sit wire 1 on top of the other parallel wire 2, where it goes through the toroid hole. And have both parallel wires touching the toroid where it crosses the outer edge where it goes to the other side of the toroid. Then sit wire 2 on the other parallel wire 1 when it again goes through the toroid hole, etc.

The benefits of not just using one smaller diameter is described in the link.

Hope I've described this correctly.

Any comments as to if this would work.

Roderick Wall, vk3yc.

11711 2015-10-01 03:06:12 kerrypwr Re: Squeeze More Performance Out of Toroidal Inductors...
G'day Rod.

I understand what you are saying but it sounds rather difficult to wind.

As someone pointed-out in the other thread, it is really only applicable to low frequencies, not RF; it's a "power supply" technique.

I posted the link just as a good example, with drawings, of the effects on capacitance  of single-layer -v- multi-layer windings; I didn't intend that the wire-forming idea would extend to what we do.

There are very different views of what "creates" capacitance between turns of a coil;  the 2006 ARRL Handbook has an interesting view but other references attribute the capacitance to other factors.

It's fun to consider the equation C = Q/V; it says that two plates don't, in themselves, have capacitance between them.

The quantity of C only appears when there is a voltage difference (which leads to a charge) between the two plates.

Incidentally, why are link coils usually wound on the "cold" end of the main coil?

The usual reason given is that there is less inter-winding capacitance at this end than at the "hot" end.

Kerry VK2TIL.