Arduino Rain Detector and Alarm Project

In this project, we are making an Arduino Rain Detector and Alarm System. It protects your electronic appliances outside your house from short-circuiting and damage by turning them off automatically when rain begins to fall. Because it only uses a few components, this circuit is simple, practical, and inexpensive. It doesn’t require much power and can easily run on 5 volts DC.

Components Required  for the Arduino Rain Detector and Alarm Project

Software

Arduino IDE

Rain Drop Sensor

How Rain Sensor Module Works

The rain sensor board functions as a variable resistor, changing from 100K when wet to 2M when dry. More current flows through the board when it is wet. Two PCB tracks run through the Rain Sensor plate. These tracks aren’t linked together. The resistance between tracks changes when water falls on the plate or board.

The opamp measures the resistance. The analog voltage output is LOW when there is more water (lower resistance). Conversely, if the amount of water is less (higher resistance), the analog output voltage is HIGH. A dry rain board produces a 5V analog output.

The LED turns on when power is applied to the module. The digital output remains LOW when there is no raindrop. When water is detected, the digital output drops to a HIGH level and the switch indicator turns ON.

Note: In some Rain Sensor Module, The digital output remains HIGH when there is no raindrop. When water is detected, the digital output drops to a LOW level and the switch indicator turns ON.

So It’s best to check your rain sensor module’s datasheet or test your module to determine the digital output when water is detected.

Preset (Trimmer pot)

Using the onboard preset, you can adjust the digital output threshold (sensitivity).

Rain Sensor FEATURES

1. Adopts high quality of the RF-04 double-sided material
2. Area: 5cm x 4cm nickel plate on side
3. Anti-oxidation, anti-conductivity, with long use time
4. Comparator output signal clean waveform is good, driving ability, over 15mA
5. Potentiometer adjust the sensitivity
6. Working voltage 5V
7. Output format: Digital switching output (0 and 1) and analog voltage output AO
8. Small board PCB size: 3.2cm x 1.4cm
9. Uses a wide voltage LM393 comparator
10. Good for weather monitoring
11. AO: Analog signal output
12. DO: TTL switch signal output

Rain Sensor Applications

1. Rain detection
2. Weather monitoring
3. Intelligent Agriculture
4. Home Automation projects
5. Rainfall intensity monitoring
6. Windscreen of car to automatically start the wipers
7. On roof of houses and offices to take necessary action against rain
8. On the roof of houses and offices to take necessary action during rain
9. It’s used in an irrigation system to automatically turn off the watering system when rain begins to fall.

Rain Sensor Specifications

For more information, you can check out the Rain Sensor Datasheet below:

Arduino Rain Detector Circuit Diagram

The rain sensor’s A0 pin connects to the analog pin A0 and D0 connects to the digital pin 2.

Arduino Rain Detector Code

By clicking the button in the top right corner of the code field, you can copy the code. Copy and paste it into Arduino IDE. 

/*** www.arduinopoint.com ***/
/*** Arduino Rain Detector Project***/

int rainAnalogPin = A0;
int rainDigitalPin = 2;

void setup(){
  pinMode(rainAnalogPin, INPUT);
  pinMode(rainDigitalPin, INPUT);
  Serial.begin(9600);
}

void loop() {
  // read the input on analog pin 0:
  int sensorAnalogValue = analogRead(rainAnalogPin);
  Serial.print("Rain sensor analog value: ");
  Serial.println(sensorAnalogValue);
  
  // read the input on digital pin 2:
  int sensorDigitalValue = digitalRead(rainDigitalPin);
  Serial.print("Rain sensor digital value: ");
  Serial.println(sensorDigitalValue);
  
//digital output
 if(sensorDigitalValue == HIGH) //High means rain detected; In some case vise versa
 {
 Serial.println("Rain Detected");
 }
 else {
 Serial.println("No Rain Detected");
 }
 delay(250);
}

Arduino Rain Alarm Circuit Diagram

LED and Buzzer connect to the digital pin 3 and 5 respectively.

Arduino Rain Alarm Code

/*** www.arduinopoint.com ***/
/*** Arduino Rain Alarm Project***/

int rainAnalogPin = A0;
int rainDigitalPin = 2;
int redLED = 3;
int alarm = 5; //PWM (~) Pin

void setup(){
  pinMode(rainAnalogPin, INPUT);
  pinMode(rainDigitalPin, INPUT);
  pinMode(alarm, OUTPUT);
  pinMode(redLED, OUTPUT);
  digitalWrite(alarm, LOW);
  digitalWrite(redLED, LOW);
  Serial.begin(9600);
}

void loop() {
  // read the input on analog pin 0:
  int sensorAnalogValue = analogRead(rainAnalogPin);
  Serial.print("Rain sensor analog value: ");
  Serial.println(sensorAnalogValue);
  
  // read the input on digital pin 2:
  int sensorDigitalValue = digitalRead(rainDigitalPin);
  Serial.print("Rain sensor digital value: ");
  Serial.println(sensorDigitalValue);
  
//digital output
 if(sensorDigitalValue == HIGH) //High means rain detected; In some case vise versa
 {
  digitalWrite(redLED, HIGH);
  tone(alarm, 5000); //the buzzer sound frequency at 5000 Hz
  Serial.println("Rain Detected");
 }
 else {
  digitalWrite(redLED, LOW);
  noTone(alarm);
  Serial.println("No Rain Detected");
 }
 delay(250);
}



Result

 You should see the rain detection message in your serial monitor. If you cannot see the desired output, ensure the circuit has been properly assembled, and verified and uploaded the code to your board.

1. Make Rain Detection, Rain Alarm, and Weather monitoring System.
2. You can make a automatic windshield wipers.
3. Make a irrigation system and acts as a water conservation device, shutting down the system in the event of rain.
4. You can make a automated system to protect the interior parts of a car from rain as well as to support the regular windscreen wiper mode.