Easy Basics: Project 013a Photoresistor or Photocell

of Acoptex.com in UNO

Basics: Project 013a

Project name: Photoresistor or Photocell

Attachments: program1

In this project, you needed these parts :

1.Aruduino Uno R3 (you can also use the other version of Arduino)

2.Arduino IDE ( you can download it from here  )

3.Jumper cables

4. Resistor 1 pc (10 KOm)

5. Breadboard

6. Photocell (Photoresistor) 1 pc


We will learn in this project about photocell or photoresistor and how to use it.

Understanding Photocell (Photoresistor)

A photoresistor or photocell is a light-controlled variable resistor. The resistance of a photoresistor decreases with increasing incident light intensity; in other words, it exhibits photoconductivity. A photoresistor can be applied in light-sensitive detector circuits, and light- and darkness-activated switching circuits.

The resistance of a photoresistor changes with incident light intensity. If the light intensity gets higher, the resistance decreases; if it gets lower, the resistance increases.

Signals and connections of photocell

Attach one end of photoresistor to power. On the otherside, attach a 10-kilohm resistor to ground. This resistor is in series with the photoresistor, and together they form a voltage divider. The voltage at the point where they meet is proportionalto the ratio of their resistances, according to Ohm’s Law. 

Build the circuit

The following picture shows the needed connections with the Arduino Uno 


Step by Step instruction

  1. Plug your Adruino Uno board into your PC and select the correct board and com port
  2. Open up serial monitor and set your baud to 9600 baud
  3. Verify and upload the the sketch to your Adruino Uno board
  4. Check serial monitor and you will see the readings from photocell


We have learned about photoresistor (photocell)


  • No libraries required for this project


  • See attachment on the begining of this project description. 

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Published at 22-07-2017
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