Re: [CAD_CAM_EDM_DRO] Figuring transformer rating?

Jan,
Congratulation on a job well done!
You did an excellent job explaining the making of a transformer.

For smaller sizes, also keep in mind that there are ready made plastic bobbins available that will save a lot of time. I specially
like the "split bobbin" type where the windings are physically kept side by side. They are great for a hobbyist since either
winding can be rewound without affecting the other one and it is easier to safe and better insulated transformer.
Bertho Boman
=====================

JanRwl@... wrote:

> Tim: See my article (I will try to leave a LINK on this letter).
>
> Two things to do: Try to "get at" the secondary wire, and "mike" it with a
> "dial caliper" (or, these days, better, a Mitutoyo LCD digital! Most
> wunnerful tool in my whole shop!). That'll give you the "wire-gage". Then,
> look it up in a "copper wire table". If you are into math, square the
> wire-dia. in mils (thousandths of an inch), and the result is "circular
> mils". Figure about 750 CM per amp. 1000 CM per amp on very
> conservartively-made and "cool-running" transformers.
>
> Second: Measure the "square area" of the core (the iron INSIDE the
> windings). Use a transformer-book (or the formula in my article, or the
> chart) and find the "V-A rating" of this size of core. You say you HAVE the
> voltage, so, divide the VA by the volts,and the result should be within 25%
> of the "amp rating". Rough, but "close enough" for all but
> expensive-computer- and military-work!
>
> <A HREF="http://members.tripod.com/~schematics/xform/xformer1.htm">Roll Your
> Own Power-Transformers!</A>
>
> Jan Rowland, Troll