I bought this rain sensor for Arduino because I was intrigued by the description, who claimed to be able to measure the size of the drops of water!
Comes with a Board that has both sides sensor and the connecting cables.
It also comes with the paddle where connects the sensor (two wires without polarity) and the Arduino (four wires: VCC, GND, A0 and D0). In D0 We have a digital sensor to rain and in A0 analog output where you measure the size of the drop of water.
There is the sensor into operation: one of the Red LEDs indicates only “circuit connected” and the other indicates that there are “rain”. The rain sensor is active only for a while, then back to “zero”.
See the test video I made:
Very interesting and really indicates the drop size. You connect the A0 to an analog input of the Arduino and make a program to return the value for analogue to computer USB. Monitoring serial monitor got larger values when the drop is small and smaller values when gout is great. Weird to be reversed, but it still looks quite useful for weather enthusiasts! I leave the link to the product: