Clap-Activated Light

Published: August 27, 2025

A simple sound-reactive project that uses a sound sensor to detect claps or loud noises and toggles an LED on or off with each clap — just like a clap switch lamp.

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📸 Preview

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⚙️ How It Works:

• The sound sensor listens for sharp sounds (like a clap).
• When a sound pulse is detected (LOW signal from D0), the Arduino toggles the LED state (ON/OFF).
• A flag system prevents multiple toggles from a single clap by debouncing the input.
• The result is a hands-free, sound-activated LED that turns on or off every time you clap or make a loud tap.

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🧰 Parts & Materials Used

Component	Notes	Amazon Link to parts
Arduino UNO (Real & Clone)	Microcontroller board	Real - Link Clone - Link
Sound Sensor Module	KY-038 or similar (uses digital OUT)	Link
LED	For visual feedback	Link
220Ω Resistor	In series with LED	Link
Breadboard + jumper wires	For easy connections	Link

Disclaimer: The Amazon links provided above are affiliate links. This means I may earn a small commission at no extra cost to you if you make a purchase through them.

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🔌 Wiring Instructions

🔉 Sound Sensor

Sensor Pin	Connect to
VCC	5V
GND	GND
OUT (D0)	D2

Use the digital output pin (OUT) on the sound sensor — not the analog one (A0).

💡 LED with Resistor

LED Leg	Connect to
Long leg (+)	D8 via 220Ω resistor
Short leg (–)	GND

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📞 Arduino Code

Language: C++

#const int soundSensorPin = 2;  // Digital OUT from sound sensor
const int ledPin = 8;          // LED connected to pin 8

bool ledState = false;
bool soundDetected = false;

void setup() {
  pinMode(soundSensorPin, INPUT);
  pinMode(ledPin, OUTPUT);
}

void loop() {
  int sensorValue = digitalRead(soundSensorPin);

  // Detect sound pulse (goes LOW on sound)
  if (sensorValue == LOW && !soundDetected) {
    ledState = !ledState;           // Toggle LED state
    digitalWrite(ledPin, ledState); // Apply the new state
    soundDetected = true;
    delay(200);                     // Debounce delay
  }

  // Reset detection flag when sound passes
  if (sensorValue == HIGH) {
    soundDetected = false;
  }
}

🧪 Notes:

• Sound sensor usually sends LOW when detecting sound
• The soundDetected flag helps avoid multiple toggles from a single clap
• delay(200) helps debounce and prevent false multiple triggers

🚀 Uploading the Code

1. Open Arduino IDE
2. Paste the code
3. Select your Arduino UNO board and port
4. Click Upload ↑

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