The light following robot is a mobile machine which is capable of detecting and following the light source on the traveling path. It is developed without the help of a micro-controller for providing easier connections and understanding of the circuit. It requires fewer numbers of electronic components and very cost-effective as well.

The concept of this light following robot is very simple. It includes two photodiodes, one on the right and other on the left. When the light falls on the right photodiode, the robot will move on the right side. Similarly, the robot will move on the left side when the light falls on the left photodiode.

Step 1:

Battery: One 9V battery will be sufficient for powering the robot. For more usages, two pairs of 9V battery may be required.
Breadboard: One breadboard is used for designing the circuit. The electronic components are connected by inserting it in the holes of the breadboard.
Gear Motor: Two 300rpm gear motors are connected with the wheel for moving the robot.
IC 7805: One IC 7805 voltage regulator is incorporated for allowing 5V of power supply to the circuit instead of 9V.
IC L293D: One L293D IC motor driver is used for driving two motors in both clockwise and anticlockwise directions.
IC LM324/358: One LM324/358 IC voltage comparator is attached to the circuit for comparing voltages across the + and – terminals.
LED: A 1.5V 200mA LED is attached to notify the falling of light source on the photodiode.
Resistor: 2 10K resistors are required for this process to reduce the voltage. The ranges of the resistors can be calculated with the help of a multimeter.
Wheels:4 or 2 wheels are coupled with the gear motor. When the motor is powered, the wheels will start to rotate and move the robot.
Wires: Two meters of both two core and four core wires will be required. For breadboard connections, two core wires should be used and for motor connections, four core wires should be used.
Capacitor: Two 10uf capacitors are implemented to store the current, equalize the power output, filter, and so on.

Step 2: CIRCUIT DIAGRAM

this circuit is very sensitive so make circuit very carefully.

Step 3: Finalize

after connecting circuit to motors,give power to circuit by 9v battery and hv fun.if u use higher rpm motors thats will be batter bcz it is very funny if u hv high rmp.