Immediate rain detection - tried and working solution?

Dear wonderous community,

Item 1) Merry Christmas! :slight_smile:
Item 2) Well done and kudos on releasing 2.2! What a milestone guys!
Item 3) General thanks for this community, which is sole responsible for LEGIO hours and a few “just a second, honey” based arguments.
…and finally;
Item 4, a.k.a. The Main Topic:

I have an over complicated and ever growing ecosystem of devices running most protocols in my Swedish home. What I am struggling with is finding a good and reliable way of detecting RAIN. Not mainly amount over time, but rather (immediate) reaction as it starts to rain…

I’ve tried both Netatmo’s and POPP’s hardware, but both are based on a tipping solution that will inevitably fail to react to light rainfall or even heavy rainfall with any speed.

The use case is to combine a contact to note that windows are open and use whatever sensor or binding to correctly note that rain is starting. I have found multiple examples of setups not exactly working, but not yet one that IS working.

Anyone out there with a working example?



Get one or better even, several cheap sensors such as this one and attach them to a RPi0 or other device capable of transforming a binary signal into a MQTT message.

Merry christmas (without too much rain :)) …

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Vielen dank, unt Frohe Weihnachten! :slight_smile:

Have you tried it yourself, by any chance? I.e. can you testify to the reliability of those particular sensors?



Sure, I use it. There’s a potentiometer you can turn how ‘wet’ the sensor plate needs to be in order to trigger, other than that its rather a question of placement. That’s why I suggested to have multiple of them, to enhance detection.

FWIW, there’s also many more sensors available for about the same price to work the same way, to detect noise, light, CO, …

Totally agree. There are also models that are built into waterproof enclosures. Cable length usually can be increased without problems.

There should be enough space inside to put some batteries and a wireless node like an ESP or a Arduino Pro Mini with MySensors wireless networking.

This is turning into a really interesting project! Thanks for the pointers, guys!


Petter, they do work, but just some pointers:
The module that is usually coming with the sensor has an analog and digital output. The analog output is rather useless as it just connects directly to the sensor and if you use that you might as well connect the sensor directly to an analog input of your processor, that way you dont have to feed an idle comparator chip.
Using it in an analog setting alows you to ‘sort of’ measure the amount of rain falling.
If you are just using it to detect rain YES/NO, then use the digital output with the potmeter set to the required sensitivity, as Markus already mentioned.
Do not expect the sensor to remain so shiny: just the outside air may corrode it and ofcourse when it is wet there will be electrolysis.

You may consider mounting it under a slight angle: this helps rain faling off, so you will also detect 'Rain End’
I have been working on something similar (presently in a corner because of other priorities), but I had been considering mounting it on some sort of heating element in order to be able to dry it faster after the rain… maybe not essential.

Using another one of these sensors as leaf moisture detector in a polytunnel, but thats another issue

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