I made a arduino based project which can switch on the light when someone passes by the door to enter the room.
it uses a ultrasonic sensor(distance sensor) to identify when someone cuts the wave and enters the room,then the servo switchs then button.
This can be modified to turn of the light also,but for that you'll need two ultrasonic sensors to count the people entered the room and how many of them left the room so that it can operate accordingly.
Step 1: Components Required.
we'll need the following things:
3.A 5v battery
4.ultrasonic sensor(distance sensor)
5.some jumper wires
Step 2: Connect the Servo Motor
connection diagram(schematics) is given here(its in pdf)
Step 3: Connect the Ultrasonic Sensor
Step 4: Upload the Code
the code file is attached here,
copy the code from the document paste it in arduino IDE an upload it :)
Step 5: Connect Your Battery
Step 6: Some Instructions!!
Step 7: Finally!!......here Is How Its Attached.
Enjoy the hands free switching :)