Re: Solid State

On Wed, 15 May 1996, Tesla List wrote:
> Have you thought about using copper strap for the primary? It is a
> preferred conductor choice for high current windings in SMPS 
> transformers.

I emphasize PRIMARY. It is certainly a good choise for primary winding.
It is usually not a good choise for the secundary. Secundary has too
many turns which will lead into much interwinding capasitance and you
will probably be in quite a bit trouble with parasitics. You have been
warned :)

>    Secondly, you said the core was O.K. I believe you're using 3C85
> material. An even better one is the Philips 3F3 material (good for 
> the MHz range and quasi-resonant supplies.

At the frequency range being applied (he was using around 100kHz I think)
it makes no difference. They are almost equally good for that low freq.

> A thought on using ring cores or U-cores etc. You can stack these to
> effectively make much bigger cores. I've seen this technique used in 
> RF power amps.

So have I. I have given it a lot of thought too. I have already desided
to stick with the E-cores becouse of heat effects I described in an other
post. However, I have desided to stack E-cores for higher power range.
I think I'll try heading for something like 3-5kW when I get the time.
2-3 smallish cores should do for that.

Stacking toroids would be a real pain anyway. Just think of winding
something like 1-200 turns on a stack of toroids. Copper foil primarys
are also automatically out. Not my idea of fun!
We have phone numbers already, why would we need IP-numbers! -unknown person

Harri.Suomalainen-at-hut.fi - PGP key available by fingering haba-at-alpha.hut.fi