At 09:18 PM 6/21/02 +1000, Roman Black wrote:

>(crazy idea following) :o)
>If your output current is relatively constant you
>can use a non-polarised capacitor in SERIES with
>your transformer primary. Use a 630v Poly cap,
>probably start with about 0.47uF and see how that
>goes. The idea is that the cap drops *about* 45vac
>(like a resistor would) but without dissipating any
>real amount of heat.

This can work but you have to be REAL careful about avoiding
resonance.  For example, one of my neat tricks is to take a fan rated for
use at 230 Vac and operate it from 120 Vac by putting a capacitor in series
with the fan motor.  With the right sized capacitor, the fan motor sees
about 180 - 190 Vac.

dwayne


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Dwayne Reid   <dwayner@planet.eon.net>
Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
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