Editing Rectifier (section)

==== Half-wave rectification ====
{{anchor|Half-wave rectification}}
In half-wave rectification of a single-phase supply, either the positive or negative half of the AC wave is passed, while the other half is blocked. Because only one half of the input waveform reaches the output, mean voltage is lower. Half-wave rectification requires a single [[diode]] in a [[Single-phase electric power|single-phase supply]], or three in a [[Three-phase electric power|three-phase supply]]. Rectifiers yield a unidirectional but pulsating direct current; half-wave rectifiers produce far more [[Ripple (electrical)|ripple]] than full-wave rectifiers, and much more filtering is needed to eliminate [[Harmonics (electrical power)|harmonics]] of the AC frequency from the output.

[[File:Halfwave.rectifier.en.svg|600px|thumb|left|Half-wave rectifier, 'U' denotes voltage, 'D' denotes a diode, and 'R' a resistance]]
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The no-load output DC voltage of an ideal half-wave rectifier for a sinusoidal input voltage is:<ref name=Lander93>{{cite book|last=Lander|first=Cyril W.|title=Power electronics|year=1993|publisher=McGraw-Hill|location=London|isbn=978-0-07-707714-3|edition=3rd|chapter=2. Rectifying Circuits}}</ref>

<!-- This is half-wave, not full-wave.  PLEASE DO NOT CHANGE TO SQUARE-ROOT 2.  You will be completely wrong and will be reverted. 
-->: <math>\begin{align}
V_\mathrm {rms} &= \frac{V_\mathrm {peak}}{2}\\[8pt]
V_\mathrm {dc} &= \frac{V_\mathrm {peak}}{\pi}
\end{align}</math><!-- 
This is half-wave, not full-wave.  PLEASE DO NOT CHANGE TO SQUARE-ROOT 2.  You will be completely wrong and will be reverted. -->

where:
: ''V''<sub>dc</sub>, ''V''<sub>av</sub> – the DC or average output voltage,
: ''V''<sub>peak</sub>, the peak value of the phase input voltages,
: ''V''<sub>rms</sub>, the [[root mean square]] (RMS) value of output voltage.