This type of sensor detects the presence of rain by the variation of sensor conductivity when it comes into contact with water. Constructively, there are simple sensors. There are two contacts linked to conducting tracks intertwined with each other at a small distance, without any contact between the two. When water is deposited on the surface, both conductors are put into electrical contact, which can be detected by a sensor. It is sent with a standard measurement board with the comparator LM393, which allows for the reading to be obtained both as an analog value and digitally when a certain threshold is exceeded, which is regulated through a potentiometer located on the plate itself. The measured analog values vary from 0 for a fully soaked plate to 1023 for a fully dry plate. The digital output shoots when the humidity value exceeds a certain value, which we adjust with the potentiometer. Therefore, we will obtain a low signal in the absence of rain and a high signal in the presence of rain.

In the case of the rain sensor, the analog signal is of no interest since the sensor does not have the necessary precision to measure the amount of water accumulated. In any case, it would be difficult to extrapolate the measurement to a value of liters per hour. That is, we cannot measure the amount of rain, only its presence. The rain sensor can be used, for example, to extend an awning or activate some other mechanism, sound an alarm, or record the amount of time (days, hours) in which rainfall occurs in a certain area. The rain sensor can also be used to detect floods, by placing it on the floor of a basement or boiler room, for example. It can also be useful to detect when the water in a tank exceeds a certain level.

Features:

• Operating voltage: 3.3V–5V
• Adjustable sensitivity: By potentiometer
• Dual output modes: Analog and digital
• Red LED: Power Indicator
• Green LED: Digital switching output indicator
• PCB measures: 30x15mm
• Sensor measurements: 54x39mm