Solar Robot by Using LDR

Solar Robot


Solar Robots are very important,  because they help save energy by using  the power from the sun. Artificial light  won’t work on the robot, because it has  solar panels. Solar panels can only be  used by the sun’s natural power. There  are so many interesting facts by using  Solar Robots.

What are solar robots?

A Solar Robot is basically a robot  that uses the solar energy instead of  electricity.

The electricity robots use electricity to get it going.

How do Solar Robots work with LDR?

Solar Robots work by the energy of the sun while the LDR is used to detect or sense the light.

C  O  N  C  E  P  T :

When A LDR (light  dependent resistor )  Subjected to white  light then the  resistance Varies. According to this variation Op-Amp & Transistor circuit gives response to drive the  motor.


LDR:- A photoresistor or light-dependent resistor (LDR)

or photocell is a light-controlled variable resister. The resistance of  a photoresistor decreases with  increasing incident light intensity.

DC motor:- Used to drive the  wheels & it should be geared dc  motor.

C  I  R  C  U  I  T :

Circuit diagram of solar robot by using LDR
Circuit diagram of solar robot by using LDR


How might Solar Robots help the earth?

Solar Robots can help the earth any way you  program it to do, but how to help the earth is up to you. These are some of my ideas, maybe you have  more.

  • They can pick up any trash anywhere someone forgets to.
  • They can help when disasters are happening.
  • They can reach places no human can go.
  • They can detect missing objects.
  • They can help with dangerous objects.

Component Required:

  • Battery: One 9V battery will be sufficient for powering the robot. For more usages, two pairs of 9V battery may be required.
  • Battery holder: It is used to connect the battery with the circuit.
  • Capacitor: Two 10uf capacitors are implemented to store the current, equalize the power output, filter, and so on.
  • Castor Wheel: One castor wheel is mounted in front of the hard board for providing easy and comfortable moving of the robot.
  • Gear Motor: Two 60 rpm 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 LM358: One LM358 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: One 1K & three 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: Two wheels (10cm dia.) are coupled with the gear motor. When the motor is powered, the wheels will start to rotate and move the robot.


  • Street lights
  • In Industries
  • At Deserts
  • In Satellites
  • This technology can also be used to measure light intensity for applications that require greater precision.
  • In Villege
  • brightness according to ambient lighting conditions.

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