The bridge rectifier uses four diodes connected as shown below. When the input cycle is positive as in part (a), diodes D1 and D2 are forward-biased and conduct current in the direction shown. A voltage is developed across R1 that looks like the positive half ofthe input cycle. During this time, diodes D3 and D4 are reverse-biased.
When the input cycle is negative as in Figure 2–38(b), diodes D3 and D4 are forwardbiased and conduct current in the same direction through RL as during the positive half-cycle. During the negative half-cycle, D1 and D2 are reverse-biased. A full-wave rectified output voltage appears across RL as a result of this action.
Bridge Output Voltage
A bridge rectifier with a transformer-coupled input is shown in Figure 2–39(a). During the positive half-cycle of the total secondary voltage, diodes D1 and D2 are forward-biased. Neglecting the diode drops, the secondary voltage appears across the load resistor. The same is true when D3 and D4 are forward-biased during the negative half-cycle.
The Spice Probe shows the electrical signals.