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!