Explain the bridge rectifier with diagrams.
- A bridge rectifier composed of four diodes D1, D2, D3, and D4 in which the input is supplied across two terminals A and B in the figure while the output is collected across the load resistor RL connected between the terminals C and D.
- Now consider the case wherein the positive pulse appears at the AC input i.e. the terminal A is positive while the terminal B is negative. This causes the diodes D1 and D3 to get forward biased and at the same time, the diodes D2 and D4 will be reverse biased.
- As a result, the current flows along the short-circuited path created by the diodes D1 and D3 (considering the diodes to be ideal).
- Thus, the voltage developed across the load resistor RL will be positive towards the end connected to terminal D and negative at the end connected to terminal C.
- Next, if the negative pulse appears at the AC input, then the terminals A and B are negative and positive respectively. This forward, biases the diodes D2 and D4, while reverse biasing D1 and D3.
- At this instant, one has to note that the polarity of the voltage developed across RL is identical to that produced when the incoming AC pulse was positive in nature. This means that for both positive and negative pulse, the output of the bridge rectifier will be identical in polarity as shown by the waveforms
- However, it is to be noted that the bridge rectifier’s DC will be pulsating in nature. In order to obtain a pure form of DC, one has to use a capacitor in conjunction with the bridge circuit.
