2.Light-Controlled LED Using an LDR and Arduino

Light-Controlled LED Using an LDR and Arduino



Components Needed:

  1. Arduino board
  2. LDR (photoresistor)
  3. 10kΩ resistor
  4. LED
  5. 220Ω resistor
  6. Breadboard and jumper wires

Circuit Connections:

  1. LDR Circuit:

    • Connect one leg of the LDR to 5V on the Arduino.
    • Connect the other leg of the LDR to an analog input pin (e.g., A0) and a 10kΩ resistor.
    • Connect the other end of the 10kΩ resistor to GND.

  2. LED Circuit:

    • Connect the anode (longer leg) of the LED to a digital pin (e.g., 13).
    • Connect a 220Ω resistor in series with the cathode of the LED, and connect the other end of the resistor to GND.

Example Code:

C++ Code
int ldrPin = A0;    // Analog pin for LDR
int ledPin = 13;    // Digital pin for LED
int threshold = 500; // Threshold value for light level

void setup() {
  pinMode(ledPin, OUTPUT);  // Set LED pin as output
  Serial.begin(9600);       // Start serial communication
}

void loop() {
  int ldrValue = analogRead(ldrPin);  // Read LDR value
  Serial.println(ldrValue);           // Print LDR value to Serial Monitor

  if (ldrValue < threshold) {
    digitalWrite(ledPin, HIGH);  // Turn on LED when it is dark
  } else {
    digitalWrite(ledPin, LOW);   // Turn off LED when it is bright
  }

  delay(500); // Wait for half a second
}

Explanation of Code:

  • Threshold: The threshold value is used to decide when the LED should turn on or off. You can adjust this value based on your ambient light conditions.
  • analogRead(ldrPin) reads the current light level, and if the value is below the threshold, it turns the LED on; otherwise, it turns it off.
  • Serial Monitor: You can view the light readings on the Serial Monitor to help determine a suitable threshold value for your environment.

Applications:

  • This project can be used to create an automatic night light that turns on when it gets dark.
  • It can also be used in security applications where lights need to be triggered based on the ambient light level.

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1.Using an LDR (Light Dependent Resistor) with Arduino to Measure Light Intensity

Image
 Using an LDR (Light Dependent Resistor) with Arduino to Measure Light Intensity. Components Needed: Arduino board LDR (photoresistor) 10kΩ resistor Breadboard and jumper wires Circuit Connections: LDR : Connect one leg of the LDR to 5V on the Arduino, and the other leg to an analog input pin (e.g., A0). Resistor : Connect a 10kΩ resistor between the LDR leg (that goes to the analog pin) and GND. This forms a voltage divider. Explanation: When light falls on the LDR, its resistance changes, affecting the voltage at the analog pin. The analog pin reads a value between 0 and 1023 depending on the light intensity. Example Code: C++ Code int ldrPin = A0; // Analog pin to which LDR is connected int ldrValue; void setup () { Serial. begin ( 9600 ); // Start the serial communication to view the LDR value } void loop () { ldrValue = analogRead (ldrPin); // Read the LDR value Serial. println (ldrValue); // Print the value to the Serial Monitor delay ( 500 ); // Delay for...
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