This document discusses different types of diode rectifier circuits used to convert alternating current (AC) signals to direct current (DC) in power supplies. It describes half-cycle rectification which uses a single diode and only utilizes half of the AC signal. Full-cycle rectification is explained as using two diodes to utilize both halves of the AC signal. Bridge rectification is then introduced as the most widely used method, using four diodes in a bridge pattern without requiring a center-tapped transformer.