- Fig. 3.3 illustrates the rectifying action of a crystal diode. The a.c. input voltage to be rectified, the diode and load R
L are connected in series. The d.c. output is obtained across the load as explained in the following discussion. During the positive half-cycle of a.c. input voltage, the arrowhead becomes positive w.r.t. bar.
- Therefore, diode is forward biased and conducts current in the circuit. The result is that positive half-cycle of input voltage appears across R
L as shown. However, during the negative half-cycle of input a.c. voltage, the diode becomes reverse biased because now the arrowhead is negative w.r.t. bar. Therefore, diode does not conduct and no voltage appears across load R
L. The result is that output consists of positive half-cycles of input a.c. voltage while the negative half-cycles are suppressed. In this way, crystal diode has been able to do rectification i.e. change a.c. into D.C. It may be seen that output across RL is pulsating d.c.
- It is interesting to see that behaviour of diode is like a switch. When the diode is forward biased, it behaves like a closed switch and connects the a.c. supply to the load R
L. However, when the diode is reverse biased, it behaves like an open switch and disconnects the a.c. supply from the load R
L.
- This switching action of diode permits only the positive half-cycles of input a.c. voltage to appear across R
L.
Wilfykil answered the question on
August 14, 2019 at 06:21