# Half Wave Rectifier Overview

## Definition of Half Wave Rectifier:

A diode is connected to an ac source and to a load resistor, RL, half wave rectifier is formed.

### Explanation:

Let’s examine what happens during one cycle of the input voltage using the ideal model for the diode. When the sinusoidal input voltage (V in ) goes positive , the diode is forward – biased and conducts current through the load resistor, as shown in diagram below.

(a) During the positive alternation of the 50 Hz input voltage, the output is like positive half of the input voltage

The current produces an output voltage across the load RL, which has the same shape as the positive half – cycle of the input voltage.

when the input voltage goes negative during the second half of the cycle, the didoe is reverse – biased.  There is no current so the voltage across the load resistor is 0 V, as shown in diagram.  The rest is that only the positive half-cycle of the ac input voltage appears across the load.  Since the output does not changes polarity.  It is a pulsating dc voltage with a frequency of 50 Hz.

(b) During the negative cycle of the input, the current is 0, so the output voltage is also “0

##### Output of Half wave rectifier seems like this:

Output of Half wave Rectifier

#### Average Value of the Half – Wave Output Voltage:

The average value of the half – wave rectified output voltage is the value we eill measure on a dc voltmeter.  Mathematically, it is determined by finding the area under the curve over a full cycle and then dividing by 2π, the number of radians in a full cycle.  The result to this is expressed in Equation below, where Vp is the peak value of the voltage.  This equation shows that Vavg is approximately 31.8% of Vp for a half wave rectified voltage.