19.04.2016, 21:19 by Mare

Today I started with realisation of some affordable weather sensors. First one is pluviometer or rain gauge. My idea is to attach some self draining container on the strain gauge. I salvaged one sensor from old kitchen scale (scrap from some other very interesting project).

First I drew my idea on paper:

The operation is simple: when rain falls into the bucket, the water level rises (A) and strain gauge measures weight of the water. Because the water bucket has limited volume and water will not evaporate quick enough, there is self-draining siphon which will drain the water when reached certain level (B). Since the diameter of the draining tube is known, the draining weight loss can be predicted and taken into the calculation during heavy raining.

First I have to find some proper pipes. There were some carbon fiber trekking sticks laying around. I took one section of the stick and voila – I got siphon tube. I wanted draining tube to match the “high tech” level of the siphon tube. I found one old fishing stick I was using for antenna pole in the past, but now it is completely destroyed except top end section with the smallest diameter.

To cover the siphon tube I turned the part with lathe from black PVC:

Next part was the lower flange. This part needs a hole for the draining pipe:

I put the slimmer draining pipe into this flange:

Now I was looking for proper bucket. We are here in wine growing region Dolenjska and the funnel looks like the most obvious solution. I found out the flange perfectly fit to the funnel. Next step was to measure the length of the draining pipe. I cut about 3 cm from the funnel edge:

After attaching the cover of the siphon tube I cut the larger pipe a bit longer than draining pipe:

And finally, the most important detail: four holes at the bottom of the siphon pipe. Water will fill the siphon through these holes:

I placed the complete siphon inside the funnel:

Next step will be holder for the strain gauge and readout circuit.

Here is one quick and shaky clip:

Stay tuned 🙂

And the best thing: I spent 1,02EUR so far for all materials.

Part Two: Strain gauge measurements