Abstract:

The Night Light Saver Electronics Mini Project is the best way of economizing the monthly Power (Electricity) invoice. It can also be use for controlling the numbers of appliances avoiding the flip-flopping of numbers of switches regularly, the concept can also be utilized for applications like automatic street light controller, automatic power shutdown in big Industrial area or Campus compound, etc.
The Project is easy to implement and is very cost effective and efficient. It can be implemented by using a LDR (Light Dependent Resistor) or an RTC chip. Using RTC and Micro controller we can keep track of time ( like a clock) and switch the light ON at specified time and switch it OFF at specified interval to save energy., but it again may not coped with the natural phenomenon every time. So the convenient way is to use a LDR.
An LDR is a photo resistor or light dependent resistor or cadmium sulfide (CdS) cell whose resistance decreases with increasing incident light intensity. It can also be referred to as a photo conductor. The LDR output data will reflects the brightness or intensity of light which can be fed to the input of micro controller from where the output load can be controlled accordingly.

Explanation:

 LDR output is connected to the Micro controller and considerations are done in the micro controller to switch the load through the driver section. The Driver section is consist of a small circuit with combination of Relay and Resistor which can also switch 230 Volts operating appliances.