1:38 PM
ajt
A voltage multiplier in its most basic sense works on the principle that "A CAPACITOR IS A CAPABLE OF STORING CHARGE AND THAT IT HAS THE SAME POTENTIAL AS THE SOURCE WHICH CHARGED IT". Now, the whole idea is that in an AC system you use capacitors in such a way that the net output voltage should be, say double of what you would otherwise get. This circuit will be called a voltage doubler. Now lets have a look at the action that actually happens to double the voltage.
The image you see is a schematic of a voltage doubler, few things to notice about it. The transformer gives output between points A and B. The load is connected between points A * and B *, but also there are two capacitors between those two points and point C is common to both.
Now to begin analyzing imagine a sine wave coming in. The first diode is forward biased and so conducts and in an attempt to do that it charges the first capacitor, now in the second half cycle of the wave the second diode is forward biased and so the second capacitor is charged. Now since the load is between the two capacitors, it is more like two batteries connected in series with each other.
Thus and the voltage in the series adds up, the net voltage across the load is twice the voltage that the transformer can deliver. Voltage multipliers are most commonly used at places where you wish to have high AC voltage when the transformer of the required rating is not available
