A rectifier contains sets of diodes that change AC power into DC power, allowing current to flow in one direction but not in the other. This process is known as rectification. Rectifiers are made using mercury arc valves, solid state diodes, vacuum tube diodes and other semiconductor technologies.

These different rectifiers also come in several varieties like single-phase, three-phase, half-wave, and full-wave rectifiers. Due to the sinusoidal nature of AC power, rectification can only produce pulses of DC power. However, full-wave rectifiers can create a more constant pulse of direct current, and this can be further smoothed out using electronic filters.

Rectifiers are components of many power supplies and also used as detectors of radio signals. Almost all rectifiers are comprised of many diodes, which are specifically arranged in order to convert AC to DC more efficiently than if only using one diode. Several varieties of rectifiers are available on the market. For instance, vacuum-tube rectifiers efficiently provide moderate, constant power.

Single Output Switching Power Supply
Rectifier – Triad Magnetics

They have essentially infinite resistance to current flow in the reverse direction because their tube does not conduct when the plate is negative. A semiconductor rectifier, on the other hand, has constant forward and reverse resistances and has the advantage of not needing a filament or heater supply.

Rectifiers are used in virtually all electronic equipment. They are often used within various power supplies when the electronics need a DC supply but the main power comes from an AC supply. Rectifiers are also usually involved in converting DC voltage from one level to another or in the detection of amplitude modulated radio signals.