**CAPACITOR POWER SUPPLY**

Here we have an
interesting problem. The resistive load on a CAPACITOR POWER SUPPLY is getting too hot.

A CAPACITOR POWER
SUPPLY uses one or more capacitors to limit the current from the
"mains." It supplies a resistive LOAD.

When the circuit is turned on, a voltage will develop across the
load. The voltage across the load will depend on its
resistance. The way to work out this voltage is quite simple.

The capacitor has a defined "resistance" at the frequency of the
"mains."

The "resistance" of
the capacitor is actually called REACTANCE or CAPACITIVE REACTANCE and
this value changes according to the frequency it is passing (the
frequency of the mains). But since the frequency of the mains is
constant, the value of "resistance" will be constant in our example.

The capacitive reactance of a capacitor is found via the following
formula:

and the "resistance" of the capacitor and the load are two resistors in
series.

There is one more point, no text book has covered.

The current through a capacitor

30/7/07