A full-wave rectifier converts alternating current (AC) to direct current (DC). This diode bridge circuit is one implementation of a full-wave rectifier. During positive half of the AC wave only two of the four diodes allow the current to pass through a resistor. During negative half-wave the other two diodes allow the current to pass through the resistor. The diodes are arranged such that the current through the resistor is unidirectional.
