I most at times put my laundry outside on the balcony and I developed this Arduino rainfall detector to let me remember when the rain starts.
A nice project for beginners, Let’s discuss how you can build a simple rain detector employing the rain sensor and a buzzer. The detector will start a beep to let you understand the rain has begun.


Raindrop sensor is primarily a board on which nickel is coated in the form of lines. It works on the law of resistanceRain Sensor module enables to measure moisture through analog output pins and it gives a digital output when a threshold of moisture exceeds.


The sensor is a resistive dipole that shows less resistance when wet and more resistance when dry. When there is no raindrop on board, it reinforces the Resistance so we get high voltage according to V=IR.

When raindrop present it decreases the resistance because water is a conductor of electricity and the presence of water joins nickel lines in parallel, so reduces resistance and reduces the voltage drop across it.



Arduino Uno
Raindrop Sensor
Piezo Buzzer
Jumper Wires


The rain sensor is just a PCB board with opens traces when a drop of water close the circuit on the board, a special circuitry gives a LOW signal to the digital output pin. It has an analog output pin as well which you can use to read analog values from the sensor.

With the potentiometer on board, you can control the threshold for digital outputs. A red LED signals that rain is detected, you can see it by touching the sensor with a hand (sometimes you have to squeeze it a little to see the light because the skin resistance is quite big).


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