The circuit consist of least numbers of electronic components, The transistor is act as a switch here. The transistor is open and close to control the Light. The exact functions of the circuit is explained here,
Delay on/off Circuit using Zener diode
- Switch Closed:
- Transistor is OFF.
- Capacitor starts charging.
- Q1 turns ON when the capacitor voltage reaches the zener breakdown voltage.
- Powers the load.
- Switch Opened:
- Capacitor discharges through R2.
- Q1 turns OFF when the voltage drops below the zener breakdown.
- Load is turned off.
This circuit essentially provides a controlled time delay in turning on and off a load based on the charging and discharging of the capacitor in conjunction with the zener diode and transistor.