Diode Rectifiers

Turning AC into DC.

A half-wave rectifier uses one diode and passes only one half of each AC cycle. A full-wave bridge uses four diodes so both halves are used, and the output is a train of positive pulses at twice the mains frequency.

A smoothing capacitor across the output fills in the gaps between the pulses and leaves a small ripple. Remember that two diodes conduct at any moment in a bridge, so the output peak is about 1.4 volts lower than the input peak.

• Bridge rectifiers use all of the AC wave.
• Larger capacitor means less ripple.
• Choose diodes rated for the peak current.

Browse all 50 physics and electronics pages  |  Back to the course index