In this tutorial, we will make a Rain Detection System using a Raindrop Sensor Module & Arduino UNO Board. A raindrop sensor, or raindrop detection sensor, is used to detect whether it is raining and also the rainfall. It is widely used in the automatic wiper system, smart lighting system and sunroof system of automobiles.

In this guide, we will first interface the Raindrop Sensor Module with Arduino. Then we will write an Arduino Code to activate a buzzer and an LED whenever the Rainfall is detected. Earlier we built Rainfall Detector using 555 Timer, which is the easiest way to play with Raindrop sensor.


Here is the list of components I am using from this Kit.

S.N. Components Quantity Purchase Links
1 Arduino UNO R4/R3 Board 1 Amazon | AliExpress
2 RainDrop Sensor Module 1 Amazon | AliExpress | SunFounder
3 Buzzer 5V 1 Amazon | AliExpress | SunFounder
4 LED 1 Amazon | AliExpress | SunFounder
5 220-ohm Resistor 1 Amazon | AliExpressSunFounder
6 Connecting Wires 10 Amazon | AliExpress | SunFounder
7 Type C USB Cable 1 Amazon | AliExpress
8 Breadboard 1 Amazon | AliExpress | SunFounder



FC-37 or YL-83 Raindrop Sensor Module

The FC-37, also known as the YL-83, is a simple sensor designed to detect the presence of water droplets on its conductor strip.

FC-37 or YL-83 Raindrop Sensor Module

By sensing moisture, it effectively determines the weather conditions, specifically indicating whether it is raining, snowing, or if the weather is dry with no precipitation.

Working Principle of Raindrop Sensor Module

A Raindrop sensor is a board on which nickel is coated in the form of lines. It works on the principle of resistance. When there is no raindrop on board. Resistance is high so we get high voltage according to V=IR.

  • Wet: the resistance increases, and the output voltage decreases
  • Dry: the resistance is lower, and the output voltage is higher

RainDrop Sensor Working Principle

When rain drop present it reduces the resistance because water is the conductor of electricity and the presence of water connects nickel lines in parallel reducing resistance and reducing voltage drop across it. The more intense the rainfall the lower the resistance.


Features of FC-37 or YL-83 Raindrop Sensor Module

  • Comes with a wide area conductor strip for sensing water droplet
  • Comes with 8 8-inch Dupont cable for detected signal transmission
  • Built-in LM393 comparator
  • Operating Voltage : 3–5 Volt
  • Signal Output Current: 15 mA
  • Type of Output : 3–5 Volt (Digital TTL)
  • Analog Output : 0–5 Volt max.
  • Comes with M3 mounting holes for easier installation
  • Built-in LED power indicator
  • Built-in LED output indicator

Pinout of FC-37 or YL-83 Raindrop Sensor Module

The FC-37 or YL-83 Raindrop Sensor Module typically includes the following pins:


  1. VCC: Powers the sensor (3.3V to 5V).
  2. GND: Ground connection.
  3. D0: Digital output (low when water is detected, high otherwise).
  4. A0: Analog output, varies with water amount detected.

The rain sensor board, which is a separate component that connects to the control board, typically has two pins:

  1. Rain Sensor Pad: This is the part of the sensor that detects rain or water droplets.
  2. Connector Pins: These pins connect the rain sensor board to the control board, typically marked with ‘+’ and ‘-‘ to indicate the correct orientation.


Rain Detection using Raindrop Sensor Module & Arduino

Lets interface the Raindrop Sensor Module with Arduino to build a Rain Detection System. First we need to assemble the hardware as per circuit diagram and then write an Arduino code, so that the Sensor Working can be tested.

Hardware Connection & Circuit

Here is the connection diagram for Rain Detection System using Raindrop Module and Arduino.

Rain Detection using Raindrop Sensor Module & Arduino

In the given setup, each component—the raindrop sensor, LED, and buzzer—is connected to a specific digital pin on the Arduino:

  1. Raindrop Sensor: This sensor is connected to digital pin 2. The Arduino will monitor this pin to detect changes in the sensor’s status, indicating the presence or absence of rain.
  2. LED: The LED is attached to digital pin 3. The Arduino controls this LED, turning it on or off based on the rain detection status from the raindrop sensor.
  3. Buzzer: The buzzer is connected to digital pin 4. Similar to the LED, the Arduino uses this pin to activate the buzzer in response to rain detection.

You can use the breadboard to assemble all the components using jumper wires.



Source Code/Program

Now lets write an Arduino Code for the Rain Detection System. In the following code, whenever the rain falls on RainDrop Sensor, the LED and Buzzer turns on simultaneously.

// Define pin numbers
const int sensorPin = 2;   // Raindrop sensor module
const int ledPin = 3;      // LED
const int buzzerPin = 4;   // Buzzer
void setup() 
  pinMode(sensorPin, INPUT);   // Set sensorPin as input
  pinMode(ledPin, OUTPUT);     // Set ledPin as output
  pinMode(buzzerPin, OUTPUT);  // Set buzzerPin as output
  Serial.begin(9600);          // Start serial communication at 9600 baud rate
void loop() 
  int sensorState = digitalRead(sensorPin);  // Read the digital value from the sensor
  if(sensorState == HIGH)  // Rain detected
    digitalWrite(ledPin, LOW);  // Turn LED OFF
    noTone(buzzerPin);           // Stop playing any tone on the buzzer
  else  // No rain detected
    digitalWrite(ledPin, HIGH);   // Turn LED ON
    tone(buzzerPin, 1000);       // Play a tone at 1000 Hz on the buzzer
  Serial.println(sensorState);  // Print the sensor state to the serial monitor