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Full-Wave Bridge Rectifier

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Recipe #13 — full-wave bridge rectifier

Four diodes can steer both halves of an AC waveform so current through the load always has the same polarity.

Why four diodes?

On one AC half-cycle, one diagonal pair of diodes conducts. On the opposite half-cycle, the other pair conducts. Either way, the top output remains positive relative to the bottom output.

Where it appears: DC power supplies, battery chargers, control boards, audio equipment, and countless electronic devices that begin with AC and need DC.

Another way to think of it

The bridge acts like a one-way traffic system. Whichever AC terminal happens to be positive is routed toward the positive DC output.

The bridge does not make perfectly smooth DC

The output is full-wave pulsating DC. A filter capacitor is commonly added after the bridge to reduce the ripple.

Try these yourself

How many diodes are used in a basic bridge rectifier? 1 2 4 8

A conventional full-wave bridge uses four diodes.

What is the main advantage over a half-wave rectifier? Both AC half-cycles are used No diodes are needed It produces perfect DC without filtering It amplifies voltage

A bridge makes use of both halves of the AC waveform.

What is commonly placed after a bridge rectifier to reduce ripple? A filter capacitor A relay contact A loudspeaker A truth table

A reservoir/filter capacitor charges near the waveform peaks and supplies the load between them.

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