# Make an Acoustic Rain Gauge (disdrometer)

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## Introduction: Make an Acoustic Rain Gauge (disdrometer)

For a project at Delft University of Technology (The Netherlands) we are building cheap, durable acoustic rain gauges, known as disdrometers. These devices "listen" to the rain and calculate the rain rate from the acoustic signal. But you can also listen to the signal: that way, you can hear the rain, even when inside a cubicle. A nice way to bring the outside environment into the office, without getting wet.

The disdrometer presented here is better for "listening", since this instructable competes in the "Art of Sound" contest. In a future instructable, a version that is optimized for measuring rain will be presented.

Acknowledgements: This instructable is based on the work of Coen Degen, student at Delft University of Technology, whom I had the privilege to supervise.

Example file: the example file is a recording of a rainstorm in Tanzania, made by Coen Degen.

## Step 1: The Components

For this disdrometer you need:
-a piezo electric element. These can be bought at radioshack. They should cost you next to nothing. The one used in this setup is also used in alarm buzzers. When deformed, a small voltage difference forms between the poles of the element. This will be used to turn the rain into en electric signal.
-a vertical piece of glass (ceiling windows are great) or
-a smell piece of glass mounted on a picture frame (see first picture)
-an audio cable with a mini-jack connector. (old earphones form old i-pods will do the trick)

tools:
-soldering gear (carefull: HOT, only use when you know how to!)
-superglue (carefull: superglue is irritating to the skin. Be very carefull!)
-a computer with a microphone input, or a sound system with a mini jack input (or any input, but you'll have to use a different connector above, of course)

## Step 2: Assembly and Listen

Assembly is pretty straightforward. Solder the plus and the minus cables of the audio cable to the piezo element. Superglue the piezo to the glass. If your using a small glass pane, duct-tape or glue the glass to the picture frame.

Be careful not to get any superglue on your skin (never, like I once did, try to open it with your mouth), if you do, get it off directly.

Stick the minijack in the microphone input of your computer and put your speakers on: now you can listen to the rain.

The file attached to this step is a wave file of a minute recording of rain (quite a heavy storm).

Good luck and enjoy!

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## Questions

Nice project!

Any progress so far?

i can't believe noone has ever made an 'ible on a tipping bucket rain gauge or a regular rain gauge.
hmmm.......

I came across one (not in instructables) but can't find it anymore, but this one may come close:

http://vwlowen.co.uk/picaxe/weather-station/page-5.htm

Hallo Nusnel, it is now januari 2011 and I realy wonder how far You are now with the final model disdrometer and the software. I've build me Your
disdrometer and the one discribed at the Vortex Electrica site.
I like the vortex model beter because it tells me when it's raining and how strong the raifall is !

Hi Drieskazoo,

we are still not in the stage where we can publish about our final disdrometer, working on the details of how to reliably calculate rain rate from the signal, taking into account that we developed this disdrometer mainly for the african market, limiting the amount of power our product may use. The solution on the Vortex website is nice: I'm very happy people are watching this instructable and improving on it. Using their type of diode would not work well for very small drops cause of the high threshold, but in general it is a very nice approach!

The disdrometer is part of the tahmo project, more on this project in this youtube:

Greetings,

Rolf

Any progress?

Interesting project. I note that you say...

a version that is optimized for measuring rain will be presented.

Have you got around to doing that yet?

Cool. We've been getting a lot of rain here lately, and more is forecasted, so I'll try this. And when you opened the superglue with your mouth, did you actually superglue your mouth shut?

Yes, right corner. Can not recommend the experience... had to pull my lips from each other in a quite painful way. Rolf

Superglue is very strong against tension forces, but weaker against shear forces.
So for example if you glue your fingers together, instead of pulling the fingertips apart, you can break the bond much easier by sliding your fingertips back and forward.
Part of the reason why it's a good idea to use glue AND nails to hold two pieces of wood together.