The operating principle of the bridge rectifier circuit is as follows: When E2 is a positive half cycle, apply a positive voltage to D1 and D3, and D1 and D3 are switched on; Reverse voltage is applied to D2 and D4, and D2 and D4 are cut off. In the circuit, E2, D1, Rfz and D3 are energized, and a positive and negative half-wave rectifier voltage is formed on the Rfz. When E2 is negative half-cycle, a positive voltage is added to D2 and D4, and D2 and D4 are switched on. Apply reverse voltage to D1 and D3, and D1 and D3 are cut off. The circuit constitutes E2, D2, Rfz, D4 energized circuit, also constitutes the other half wave of positive and negative rectification voltage on the Rfz. This is repeated and the result is a full wave rectifier voltage at the Rfz. The waveform diagram and the full-wave rectifier waveform diagram are the same. It is also not difficult to see from the figure that the reverse voltage of each diode in the bridge circuit is equal to the highest value of the secondary voltage of the transformer, which is half less than the full wave rectifier circuit [1].