CV Transformer - Capacitor on separate winding ?

[Paul Koning]

>>>>> "der" == der Mouse <mouse at rodents.montreal.qc.ca> writes:

 >> As usual during initial power tests - pulled all cards, and began
 >> to power-up through variac and series light bulb - Bulb glows
 >> brightly as power comes up, suggesting system is drawing far more
 >> power than it should, [...]

 >> Can anyone explain to me what is going on, and why the unloaded
 >> power supply is drawing so much on it's input?

 der> One possibility comes to mind immediately.

 der> Current flowing != power being drawn.  A serial resistance will
 der> show you, approximately, current drawn.  But if the load is
 der> heavily reactive, as may well be the case here, it's entirely
 der> possible for the current drawn to be all out of proportion to
 der> the power consumed.

 der> An ideal capacitor or inductor, for example, presents a purely
 der> reactive load and consumes no power even though it draws
 der> current. 

That's what I figure, too.  With a dual trace scope, or an X/Y scope,
you can test this easily -- set one channel to measure the current
(voltage across a *small* series resistor) and the other voltage.
Trigger on one, and observe the two traces.  Or feed them to X and Y
and see how close the Lissajous figure is to a circle.

    paul