Hack a Rain Gauge - Project Stage 2

Next Step

So what’s the problem?

Well, I would like my rain gauge to do a little more.  

Firstly, the unit isn’t very reliable at recording lower intensity rainfall events.  Where I live we get a lot of fine drizzle. Usually the rain gauge doesn’t pick this up at all.

Secondly, all I get is total daily rainfall, for example 2mm/day or 10mm/day.  This doesn’t tell me if the rain came down in one heavy down pour in a few minutes or results from hours of fine rain.

Thirdly and most importantly the data cannot be exported from the system.  It isn’t saved to removable flash drive or anything like that.  Don’t get me wrong I’m not complaining about the quality of my £25 system!  It is good value for money, but  I’m not going to splash out on a higher spec unit and besides it will be fun to develop my own.

In terms of the new unit we have 2 key challenges,

1. Recording the data
2.  Improving the accuracy

Recording the data

I want greater accuracy and the ability to export the data

Our new system will be based on my existing system.  For me the hardest part of creating a tipping bucket rain gauge is getting one that reliably tips and has an accurate size of bucket.  There are projects on the internet that build their own tipping buckets and sure you could 3-D print one, but a doubt if either is anyway near a good or cheap as a modifying an existing system.  You most likely will be able to pick-up the tipping bucket part on its own from e-bay if you need one (and not the indoor sensor part which you don’t need for this project).

How do the electronics work?

Reed switch

The tipping bucket has a magnet attached to it.  When the bucket tips the magnet travels past a reed switch it opens and the circuit is broken.  The number of times the switch is opened by the magnet gives us the number of time the bucket tips.  

The rain gauge I have then sends this data to the indoor unit via 433Hz radio signal. Now we could try to de-code the radio signal (I did ask the manufacture for the code but they declined for understandable reasons).  

Anyway we would still need a device to receive the signal and record the data.  For this project we are going to use an Arduino.

I like to develop my project in steps.   I find it much easier to de-bug projects this way.  For this project,
A – Install the new Reed switch in tipping bucket and
Connect it to an Arduino.
B – Add a shield for recording the data to an SD card

Reed switch


The reed switch sits very close to the tipping bucket mechanism.

Integrated into the plastic is a magnet that opens the switch each time the bucket tips.


I’ve removed the screws holding the electronic in so we can get a closer look.

Let’s replace the existing electronics with a Reed switch attached to an Arduino

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