Re: Transformer

Jan,
Thanks so much, just spent the last 10 minutes scanning the "roll
your own". I've been thinking about doing just that, but didn't have
any idea where to find the info I need. This is it!

I'm a bit skeptical about being able to find core material and wire.
Where can I get wire, and are small transformer shops so abundant
that I should be able to find one easily??

Anyway, just for the info, if the step-up is rated at 2.5 amps@220V,
then can I assume I can get 5a @ about 50v, by reverse wiring it?.

What I'm really thinking about is a 76volt DC power supply, capable
of putting out 20 amps.


Again many thanks
Jerry

--- In CAD_CAM_EDM_DRO@egroups.com, JanRwl@A... wrote:
> In a message dated 14-Sep-00 20:28:34 Central Daylight Time,
Ozzie@h...
> writes:
>
> << Can I use a stepup (115v to 220v)transformer in reverse and
apply
> 115v to the output and get approx 55v output? >>
> Jerry: Yes and no. A transformer is "normally" designed to handle
about a
> 5% drop due to losses in the iron and copper. That is, the
windings-ratio on
> the secondary will have about 5% more turns than if there were NO
losses
> ("ideal" situation, which "real-life" does not include!). But, you
can
> always put in LESS voltage into a transformer than the "input
winding" is
> designed for, that is, yes, you could put in 115 to the 220 V
winding. But
> you wouldn't get "exactly" 55 volts out. Maybe more than that,
> "open-circuit" (load is ONLY voltmeter), and LESS than that, if you
draw
> current. BUT... Be careful, there! You must NEVER attempt to
draw more
> current out of a winding than it was designed to handle (in or
out). Because
> the "current load" determines the wire-diameter used to make the
winding, and
> attempting to draw more than it was designed for will overheat the
winding,
> probably "whole transformer", and "cook things"! And, when
that "sudden
> short" suddenly finally happens, SMOKE, and probably fire, and, is
your
> insurance paid-up???
>
> See my article, "Roll your own..." It may have some info. which
will amuse...
>
> <A
HREF="http://members.tripod.com/~schematics/xform/xformer1.htm">Roll
Your
> Own Power-Transformers!</A>
>
> Careful! Jan Rowland, Troll