[Milsurplus] OK Smart People: Capacitive Voltage Divider?

[J. Forster]

David,

Not a good idea, IMO.

That said, the formula for a voltage divider is the same as for resistors,
if you relace the resistances by the capacitive reactances Xc = 1 /
2*Pi*F*C

where F is Hz; C is Farads. The result is in Ohms.

Remember that a voltage divider needs to have about 10x the current
through it as the load draws. This means pretty beefy caps.

You'd be much better off using somethying like a 12.6 V @ 1A filament
transformer, with the secondary wired to buck the hot side of line. That'd
get you from 125 to about 112.

Best,

-John

======================



> I'm resurrecting a National NC-100A.
> Sounds beautiful.  Nice AM, BCB and SWL rig.
> One problem:  our blasted 125 Volt AC power lines.
> This rig wants 110 volts and 125 is very tough on it.
> There is no room to hog-wire in a bucking transformer,
> so that's out.   Niether can I dedicate a variac to running
> this receiver.
> I understand one can use capacitors as an
> AC voltage divider by placing one in series with
> a leg of the transformer primary and one across the
> transformer primary.
>
> How can a dummy who can barely do the math
> needed to number book pages determine what
> values to use to drop this primary voltage from
> 125 to 110? Or even if it will work?
>  Easy!  He askes the dozens of people
> smarter than him on the mailing lists.
> Ain't that cool?  ;-)
>
> TNX ES 73 DE Dave AB5S
>
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