Zener Diode for Wave Shaping
Zener diodes are also used to convert sine wave into the almost square wave. For this, A circuit is arranged as shown in diagram 1. During positive as well as negative half cycle, when the voltage across the didoes is below zener value they offer a high resistance path and input voltage appears across the output terminals. However, as the input voltage increases beyond zener value, the zener diodes offer a low resistance path and conduct large current. This result in the heavy voltage drop across series resistor R and hence peaks of the input wave and clipped-off when appearing at the output as shown in diagram 1. Thus an input sine wave is clipped-off at the peaks and almost a square wave appears at the output.