Jännitekertoja

Jännitekertoja, often translated as voltage multiplier, is an electronic circuit that produces a higher DC voltage from a lower AC voltage. It achieves this by using a combination of diodes and capacitors. The fundamental principle is to rectify the AC input and then "stack" the rectified voltage levels.

The simplest form of a voltage multiplier is the half-wave voltage doubler. This circuit consists of two diodes and two capacitors. The AC input is fed to the first diode and capacitor, which acts as a half-wave rectifier. The second diode and capacitor then take the rectified voltage and add it to the original voltage, effectively doubling it.

More complex voltage multipliers, such as triplers and quadruplers, can be constructed by adding more stages of diodes and capacitors. Each stage typically adds a fixed increment to the output voltage, proportional to the peak AC input voltage. This allows for the generation of very high DC voltages from relatively low AC sources.

Voltage multipliers are commonly used in applications where high voltage is required but a bulky and expensive high-voltage transformer is undesirable. Examples include high-voltage power supplies for cathode ray tubes in older televisions and oscilloscopes, electrostatic generators, and some types of laser power supplies.

While effective, voltage multipliers can have limitations. The output voltage can sag under load, and the ripple on the DC output can be significant, often requiring additional filtering. The efficiency of a voltage multiplier also decreases as the multiplication factor increases.