What Is a Voltage Doubler?

A voltage doubler is an electronic circuit designed to boost the voltage from its input to an output that's nearly twice as high. It cleverly uses capacitors and diodes to accumulate charge on one cycle and release it on the next, effectively doubling the voltage. Intrigued by how this can power your devices more efficiently? Let's examine its practical applications together.
Cindy Quarters
Cindy Quarters

A voltage doubler is an electrical device that takes in an alternating current (AC) as its input and outputs direct current (DC) with twice the input voltage, normally to a transformer. There are many different types of voltage doublers, but they all work in essentially the same manner. Input voltage is passed through a series of capacitors that store the charge, and through diodes that direct the charge. Capacitors and diodes are placed in such a way as to capture and boost the incoming power, ultimately doubling the output.

In its simplest form, a voltage doubler may consist of nothing more than two components, the diode and the capacitor. In practice, such a system does not work well and requires the use of additional components in order to produce good-quality output. These additional components help to eliminate spikes and ripples that can be caused during the doubling process, thus allowing the output voltage to be more useful.


A voltage doubler works by capturing incoming voltage through a series of capacitors. One capacitor captures the forward-moving voltage, and another captures the current when it moves in the opposite direction. When both capacitors are fully charged, the current is released. Since the capacitors are placed in series, which means both are on the same line, the two captured voltages join together to become a single voltage that is double that of the original amount.

The load on the circuit determines if a voltage doubler will actually double the input, as a significant drain on the system results in decreased input. The diodes in the doubler keep the electricity from moving back to the source. This means that once the voltage passes the diodes, it cannot move backward and out of the system, only forward. If a diode is installed incorrectly in a voltage doubler, this creates the possibility for explosion, as voltage tries to go both into and out of the system through the same location.

By increasing the number of capacitors that are capturing the incoming voltage, a voltage doubler can be made to triple or even quadruple the incoming voltage through the use of additional circuits. As long as the outputs of all of the capacitors operate in series, the output voltage will be increased. There are some safety concerns with such a setup, however. An increase in the number of circuits is also considered not very cost-effective, but it will be effective if set up correctly.

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