Diode as a Rectifier
By A diode is commonly used as a rectifier in electronic circuits to convert AC voltage to DC voltage. There are two main types of rectifiers that use diodes:
Half wave rectifier
A diode can be used as a half-wave rectifier to convert AC voltage to DC voltage. The half-wave rectifier circuit uses a single diode to allow current to flow in only one direction.
Here's how a diode works as a half-wave rectifier:
- During the positive half-cycle of the AC voltage, the diode is forward-biased and conducts current through it. The voltage across the load (resistor) is equal to the peak voltage of the AC waveform.
- During the negative half-cycle of the AC voltage, the diode is reverse-biased, and no current flows through it. The voltage across the load is zero.
The half-wave rectifier circuit only allows current to flow through the load during the positive half-cycle of the AC waveform, while blocking current during the negative half-cycle. This produces a pulsating DC voltage across the load. Half wave rectifier has some disadvantages like low efficiency (40.6%), high ripple voltage, and poor voltage regulation.
Full wave rectifier
A diode can be used as a full-wave rectifier to convert AC voltage to DC voltage. The full-wave rectifier circuit is more efficient (81.2%) than the half-wave rectifier because it allows current to flow through the load during both the positive and negative half-cycles of the AC waveform. This produces a smoother DC voltage across the load with lower ripple voltage.
The basic full-wave rectifier circuit consists of four diodes arranged in a "bridge" configuration, as shown in the diagram. During the positive half-cycle of the AC voltage, diodes D1 and D2 are forward-biased and conduct current through them. At the same time, diodes D3 and D4 are reverse-biased and block current.
During the negative half-cycle of the AC voltage, diodes D3 and D4 are forward-biased and conduct current through them. At the same time, diodes D1 and D2 are reverse-biased and block current.
The full-wave rectifier circuit allows current to flow through the load during both the positive and negative half-cycles of the AC waveform. This produces a DC voltage across the load that is equal to the absolute value of the AC voltage.
