This is simple arduino project; turn on LED when it's dark and turn off when is light.

Step 1: Hardware Required :

  • Arduino Uno
  • LED
  • LDR (photoresistor)
  • 220 and 10k ohm resistors
  • Wires
  • Breadboard

Step 2: LED Connection

  1. LED attach to board
  2. Resistor (220 ohm) one leg attach to LED long leg
  3. The green wire attach to resistor's empty leg
  4. The brown wire attach o LED short leg

Step 3: LDR Connection

  1. LDR attach to board
  2. Resistor (10k ohm) attach to LDR one leg
  3. The purple wire attach to LDR other (empty) leg
  4. The yellow wire attach to LDR and resistor same column
  5. The white wire attach to resistor empty leg

Step 4: Arduino Connections

  1. The green wire connect to digital 13 from resistor leg
  2. The brown wire connect to GND from LED short leg
  3. The purple wire connect to +5V from LDR
  4. The yellow wire connect to A0
  5. The white wire connect to GND

Step 5: Code

const int ledPin = 13;

const int ldrPin = A0;

void setup() {


pinMode(ledPin, OUTPUT);

pinMode(ldrPin, INPUT);


void loop() {

int ldrStatus = analogRead(ldrPin);

if (ldrStatus <=300) {

digitalWrite(ledPin, HIGH);

Serial.println("LDR is DARK, LED is ON");


else {

digitalWrite(ledPin, LOW);




Step 6: If It Helps, Please Subscribe

First of all, I would like to thank you for reading this guide ! I hope it helps you.

If you want to support me, you can subscribe my channel and watch my videos.

Mert Arduino Tutorial & Projects

<p>i finally did it. thanks a lot for your easy explanation </p>
This is a very nice tutorial if you want to extend the circuit to more complex functions afterwards. Will for sure be useful to many tinkers. For a basic circuit like this no Arduino is needed, there are instructables on this.

About This Instructable




Bio: I've just started a youtube channel, hoping to help people, share some of my knowledge and learn myself. My next Youtube (and Instructables) tutorials ... More »
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