Many times it happen when somebody comes home in night and press the door bell, We search for the porch light switch.  To identify that the visitor who as press the door bell is known or unknown person before opening the door. This circuit will help you to solve the problem.  When a visitor press the doorbell switch it will automatically on the porch light after sometime so that when you reach near the door you don’t have to search for light switch. This circuit will automatically off the light after some time. This circuit also has the facility to on the porch light from inside the house. In day time you can off the light with the help of switch S3. Doorbell cum light has inbuilt doorbell so you do not require to purchase a door bell.