[Eeyore]

Arny Krueger wrote:

"Eeyore" wrote
Arny Krueger wrote:

Theoretically, cables made up of fine wires or small individually
insulated wires does not address skin effect. Lab measurements bear that
out. Therefore Litz wire doesn't do a lot for skin effect.

Well..... it has to or high frequency smps transformers would be hoplessly
inefficient.

The smps transformers I've taken apart were made with plain enameled wire.
Sometimes a couple of strands for one winding, but I think that was for a
bifilar winding. Heck many SMPS only run at 30-60 KHz - I used to see their
(small) effects when I recorded at 24/96.

Very few smps designs run below 100kHz now. The first one I did was 130kHz. At
such frequencies you don't want any conductor 0.3mm dia.

I took apart a low-voltage 12V DC halogen lighting 'transformer' recently. The
smsps secondary was about 10 strands of ~ 0.3 dia.

200-300 kHz is quite common now, 500kHz not unusual. The parts are available
including the low-loss ferrites for up to 1MHz. Printed windings ( Cu foil 35-70
um ) are sometimes used with these.

Graham