4 Jul
2008
4 Jul
'08
6:40 p.m.
Roy J. Tellason wrote:
Now, this is more your filed than mine, but the rating of a transformer
is determined by at least 2 things :
1) 'Copper losses' due to the resisance of the secondary winding
2) Ditto for the primary winding
3) The size of the core / the flux density in the core.
Now, I think that (2) and (3) would be the same whether you used the
whole winding or half the winding at twice the current. And for small
transformers, the copper loss in the secondary is rarely the limiting
factor (For example it's very rare for the seocndary to be the winding
that fiales on a burn-out).
Soe while I'd not try and use half the secodnary at twice the rated
current, I think you would get away with rather more than the current you
could draw if you used the whole winding.
But then again I like over-rating transformers, so I'd probably not do
this anyway.
-tony
If you're talking about a full-wave (4-diode)
bridge across a 9V winding you
can get the same result by using two diodes with an 18V winding. For the
other, where what you want is only 9VAC, you can use half the winding,
just one end and the center tap and not use the other end.
That would be ideal. Just remember that the 18V winding will be rated
for half the current that a 9V winding would have been, and that still
applies even if you only use half the winding. In this case I'd