With the growing popularity of smartphones, android based projects are being preferred these days.
Project 1
The projects involve the use of Bluetooth technology-based devices. These Bluetooth devices require about 3V voltage for operation. In such cases, a Zener diode is used to provide a 3V reference to the Bluetooth device.
Project 2
Another application involves the use of Zener diode as a voltage regulator.
When AC voltage is rectified by the diode and filtered by the capacitor. This filtered DC voltage is regulated by the diode to provide a constant reference voltage of 15V. This regulated DC voltage is used to drive the control circuit, used to control the switching of light, as in an Automated Lighting Control System.
Real Life application: We use Zener Diodes in Medical Instruments. Like, Pulse Checking Machine, we use Zener Diode to cancel out the frequency generated by the Electricity(in India it is 50Hz), to determine the accurate frequency of the heart.
Research paper on Automated Lighting Control System
More details on Zener Diode