In electronics, rectification is the process of changing alternating current into direct current. A rectifier makes current flow in one direction, although the initial output may still be uneven or “pulsating” rather than perfectly smooth.
The most common rectifying components are diodes. A diode allows current to pass readily in one direction and blocks it in the other, so it can remove one half of an AC waveform. A single diode produces half-wave rectification, while a bridge rectifier uses four diodes to produce full-wave rectification from both halves of the AC cycle.
Power supplies usually add a transformer, capacitors, and sometimes voltage regulators. The transformer can change the voltage before rectification; capacitors smooth the pulsating DC; and regulators help maintain a stable output. This chain is used in chargers, radios, computers, televisions, and many other electronic devices.
A common misconception is that rectification alone creates perfectly steady battery-like electricity. It does not: rectification changes the current’s direction, while filtering reduces the remaining fluctuations. The reverse process—changing DC into AC—is called inversion and is performed by an inverter.