Half wave rectifier

A device that converts one polarity (positive or negative) of input AC into output DC is known as Half-wave rectifier. OR

A device that converts half-cycle of input AC into output DC is known as Half-wave Rectifier.

As shown in the figure below.

Half Wave Rectifier (Circuit Diagram)

When the positive half cycle of input AC wave comes, than the diode is forward biased and switched into ON condition, So it conducts and positive half-cycle of input AC is dropped across RL.

When the negative half cycle of input AC comes, the diode is reverse biased and switched to OFF condition. Thus the diode doesn’t conduct and no voltage is dropped across RL. So negative half cycle is skipped.

So, the output is not a steady DC but a pulsating DC, having a specific frequency equal to that of the input voltage frequency.

Since only half cycle of input wave is used, it is called half wave rectifier.

If it is required to step up or step down the input voltage, we will have to use a power transformer as shown in figure, below.

Power Transformer (Step-up action)