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What Does Rectifier Mean?

A rectifier is an electrical device composed of one or more diodes that converts alternating current (AC) to direct current (DC). A diode is like a one-way valve that allows an electrical current to flow in only one direction. This process is called rectification.


A rectifier can take the shape of several different physical forms such as solid-state diodes, vacuum tube diodes, mercury arc valves, silicon-controlled rectifiers and various other silicon-based semiconductor switches.

Rectifiers are used in various devices, including:

  • DC power supplies
  • Radio signals or detectors
  • A source of power instead of generating current
  • High-voltage direct current power transmission systems
  • Several household appliances use power rectifiers to create power, like notebooks or laptops, video game systems and televisions.

Techopedia Explains Rectifier

A rectifier is an electrical device that converts AC to DC. AC regularly reverses direction, while DC flows in one direction only.

Rectification produces a type of DC that encompasses active voltages and currents, which are then adjusted into a type of constant voltage DC, although this varies depending on the current’s end use. The current is allowed to flow uninterrupted in one direction, and no current is allowed to flow in the opposite direction.

Almost all rectifiers contain more than one diode in particular arrangements. A rectifier also has different waveforms, such as:

  • Half Wave: Either the positive or negative wave is passed through and the other wave is blocked. It is not efficient because only half of the input wave form reaches the output.
  • Full Wave: Reverses the negative part of the AC wave form and combines it with the positive
  • Single-Phase AC: Two diodes can form a full-wave rectifier if the transformer is center-tapped. Four diodes arranged in a bridge are needed if there is no center-tap.
  • Three-Phase AC: Generally uses three pairs of diodes

One of the key problems with rectifiers is that AC power has peaks and lows, which may not produce a constant DC voltage. Usually a smoothing circuit or filter needs to be coupled with the power rectifier to produce a smooth DC current.


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Margaret Rouse
Senior Editor
Margaret Rouse
Senior Editor

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.