This document discusses full wave rectifiers, specifically the center tap full wave rectifier and the full wave bridge rectifier. It explains that full wave rectifiers allow current to flow in the same direction during both half cycles of the input AC signal. A center tap full wave rectifier uses two diodes and a center tapped transformer, while a full wave bridge rectifier uses four diodes in a bridge configuration without needing a center tapped transformer. The document analyzes the voltage outputs and advantages/disadvantages of each circuit.