Re: 28v power transformer

Yikes! Good point. The devil's in the details, as they say. Connect
only *two* wires from *separate* coils, then measure the voltage
across the unconnected ones.

Don

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Roy J. Tellason"
<rtellason@b...> wrote:

> On Wednesday 21 April 2004 01:25 pm, theowyn wrote:
> > I would take a meter to the primary for starters. You probably

will

> > see two separate coils which have *equal* resistances of a few

ohms.

> > I would use a Variac or another low-voltage transformer to feed a
> > couple volts into the secondary side and verify the you're getting

the

> > *correct* porportional voltages on the primary.
>
> This is a good approach, except the fact that a variac typically

provides no

> isolation...
>
> > Then try paralleling the primaries to find the proper polarity

between the

> > coils (a wrong polarity cancels most of the magnetic field which

results in

> > high currents flowing.) At this point you know enough to hook it

up

> > properly.
>
> Again, this isn't quite right. If you tie two ends together, then

the coils

> will be either in phase or out of phase. If they're in phase with

each

> other, there will be little or no voltage difference between the

two

> unattached wires. If they're out of phase, the voltage will be

_twice_ that

> of either winding -- at which point tying _those_ ends together as

well more

> than likely _will_ let the magic smoke out...
>
> > Good luck and don't let out the magic smoke! ;-)