I got a couple of transformers rated 950 VA each from eBay, to rewind the
secondaries for my own voltages. However, it turns out the secondaries are
made of thick copper foil. I can see this having an advantage because
there is less wasted crossection, making for a smaller transformer, and the
turns ratio is only about 1.5 turns/Volt. But would a foil winding
compromise performance for use in audio power supplies? And, when
rewinding, if I use wire instead, would I loose much by being able to have
less crossection filled with conductor?

Another thing, I usually use nail polish to put together the laminations as
there's no shellac or appropriate epoxy locally, but it takes very long to
dry. I'm wondering if I can put this in the oven at say 70*C to speed up
drying, or would that burn the nail polish?

Prune wrote:

Another thing, I usually use nail polish to put together the laminations as
there's no shellac or appropriate epoxy locally, but it takes very long to
dry. I'm wondering if I can put this in the oven at say 70*C to speed up
drying, or would that burn the nail polish?

Blow dryers dry nail polish quickly. They are also handy for thawing
frozen door locks on your car in the Winter.

--Bryan

Prune wrote:

I got a couple of transformers rated 950 VA each from eBay, to rewind the
secondaries for my own voltages. However, it turns out the secondaries are
made of thick copper foil. I can see this having an advantage because
there is less wasted crossection, making for a smaller transformer, and the
turns ratio is only about 1.5 turns/Volt. But would a foil winding
compromise performance for use in audio power supplies? And, when
rewinding, if I use wire instead, would I loose much by being able to have
less crossection filled with conductor?

Rewinding is a huge pita.

The foil secondariers are probably good for what they have to do,
ie, provide high current at low voltage.

Transformer windings should have no more than
3 amps per square mm of copper section, so its
easy to work out the approximate current ratings for a given design.



Another thing, I usually use nail polish to put together the laminations as
there's no shellac or appropriate epoxy locally, but it takes very long to
dry. I'm wondering if I can put this in the oven at say 70*C to speed up
drying, or would that burn the nail polish?

You need transformer varnish, and a temerature controlled oven.
A vacuum chamber might also be a help.

Nail varnish only belongs on the fingernails of silly,
vapid, and expensive sheilas you are better off without.

Patrick Turner.