How optical rain sensor works?
Here is a simple video of how this rain sensor works.
Rain Sensor Video Demonstration
In this clip, the rain sensor begins the test without any water drops onto it.
The sensor is powered up by 12V and has been set to the function Mode 1 – Rain Sensing (easiest to use).
This video demonstration is based on the most popular configuration settings.
Then some water is sprayed onto the sensor.
A green light gets lighted up indicating that rainwater is detected.
The water droplet that is on the dome surface disturbs the IR light ray inside the sensor.
This cause some disturbance to the sensor and hence a detection of rain.
The sensor detection will remain activated as long as the rain continues to disturb the sensor.
As long as there is an activity (any motion of water) on the surface of the sensor, the sensor will remain activated.
If there is no activity (no rain) on the sensor for about 3 minutes, the rain sensor will deactivate.
In this video, you get to see the sensor deactivated after 3 mintues of inactivity. A short while later more water is sprayed onto the sensor.
You get to see the green light gets activated again.
As long as the rainwater activity continues, this rain sensor will remain activated.