Zener Diode Signal Limiter
Zener diode has been commonly used as signal limiter. With a single diode and a resistor, the limiter will limit the half cycle of a signal to it’s forward bias and and the other half cycle to its reverse breakdown voltage.
Using two back-to-back Zener diodes, the limiter will now limit full cycle symmetrically. In audio application, limiting an audio signal before power amplification will prevent a destructive high power output at the speaker.