nice! waiting your feedback
Have you cut the contacts on the bottom side of the rain module PCB? This is essential otherwise both sides have to dry and water below the board stays there much longer. I simply cut the copper with the knife, someone else here did it by drilling holes through the board and soldering contacts only on the upper side. Funny thing, once all of a sudden on a sunny day a bee poop fell to the sensor and activated it, I thought that I’ll have to clean it to make it work again. Guess what, poop dried eventually in an hour and stopped conducting current.
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I did cut the underside tracks when building the first version. The issue is that a leak sensor is super sensitive - I tried a 1Mega ohm resister this morning and even that triggered it. The rain sensor module needs to be completely dry and clean to work hence why I had to change tack, that sensor is not suitable at all for use with a leak sensor. The funnel worked great with tap water, and I can move the probes closer or further apart to detect rain water.
Will update the thread once we get some rain.
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Update, just woke up to a short rain shower and the funnel sensor worked as planned. It was triggered just as it started 
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Worked like a charm! Got a rain sensor (Aliexpress) with contacts at the back side ( ), some simple box from Aliexpress and the Aqara doorsensor (left the reed-relay attached for easy testing)! Goodbye to OpenWeather/ClimaCell rain “predictions” and Hello very sensitive rain sensor telling me that it is raining in my own backyard! Thanks so much for this brilliant (and cheap) idea! 20220702_171001|690x388
This looks like a really good build - I might try and replicate it! Once it stopped raining how long did it take for the sensor to update?
It triggers as soon as rain bridges the 2 wires. As the rain can drip through the funnel the sensor then clears until there is another amount of rain to bridge the wires again. I only trigger on the first alert then stop further alerts for another hour - I use NodeRed so this is very easy to do.
This home built sensor will not trigger on a slight shower so it needs a normal downpour to trigger. Moving the wires closer together would make it more sensitive. It’s fine for me as it is.
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I made mine with an Aqara leak sensor. The lugs loosen on the bottom and the wires attach easily. The sensor is inside the garage and the module is outside. I ran the wires through the wall to get the module outside.
I removed the plug off the module and soldered wires directly to the board. The plug holds water and cause it to take too long to clear. I also covered the back of the module with tar tape so that only the surface can get wet. It clears in about 20 minutes. Sooner if there is a breeze.
I mounted it directly to the siding on my home a couple feet above the air conditioner compressor. The air flow from the unit helps to dry the sensor. Still in testing phase, but works well. It was very wet out this morning from dew and the sensor stayed dry.
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I found my sensor would not clear at all hence why I built my own with a funnel and 2 wires. Not had much chance to test it as we’ve not had decent rain for over a month 
I found my sensor would not clear at all hence why I built my own with a funnel and 2 wires. Not had much chance to test it as we’ve not had decent rain for over a month
Most likely the connector. Water gets in there and under it.Thats why I cut it off.
Just got a good rain.
Rain Sensor detected
2:06:37 PM
Rain Sensor cleared (no detected)
3:14:35 PM
Rained pretty heavy for about 15 minutes.
The setup seems solid. Morning dew is not an issue. Things can be pretty wet out and it shows as dry in the morning. Adding the backing to the module helped out alot.
If it rains after dark, it will show as wet almost all night. That was one night and Im not sure how long it rained that night. Could have rained most of the night for all that I know… Not really an issue for me as I want this to let me know if its raining during the day in case I have tools outside or the grill is uncovered.
How did you remove it?
thanks for the nice and easy build! just built the sensor with an Aqara door sensor and it works like a charm, actually it is very sensitive to any contact, for example if you touch the sensor it immediately closes the contact. be sure to place it wisely in the garden and that your neighbours water sprinklers doesnt affect it.
I sealed the whole rain sensor with black silicon, even all holes. with that no water should run under the sensor and triggers the contact by error.
I drilled a hole in the top and ran the cables inside to the door sensor. the hole is sealed with hot glue.
this is how mine looks like:
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Awesome idea!!
may I ask how do you get the cables out of the junction box without breaching the waterproof condition of the junctionbox?
hi! what sort of glue did you use?
actually I drilled a hole in the top part of the case and sealed it with a sealant. The type of glue is called Sikaflex. It is kind of flexible to withstand thermal expansion.
Actually any kind of external rated silicone sealant will work (Sikaflex is one).
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What sensor did you use? Aqara ? or Linking ? And do you not find rain stays on the board for a long time, and you need to place it at an angle? I have no problem detecting the rain, the problem is detecting when it stops.
Hi Guys,
Very interesting topic. I like to build such a sensor but as i read from many of you, the sensor stays wet for many hours before drying. We need to brainstorm a bit. So let me throw an idea on the table:
Since the door sensor only needs to connect the 2 ends of the reed to activate, why don’t we use a non-conductive material that when it gets wet, it becomes conductive? For example, a piece of cloth. We connect both ends to the cloth and because it’s non-conductive the sensor appears “Open” (in this case Dry"). When the cloth gets wet and for as long as it is wet, the sensor will appear “Closed” (or wet for our purpose).
If we place this setup vertically, the water on the cloth will dry from top to bottom and as the top will be dry, it will open the circuit and the sensor will show that it’s not raining.
In theory it could work if we find a non-conductive material that dries very fast 
What do you think of this idea?
Thanks
M
Here’s another idea. Put rain-x on the sensor (angled of course). It should make the water bead off more easily and dry faster.