The cylinder has a valve at the bottom. A motor opens and closes the valve. The GoGo Board controls the motor.

Conductivity sensor

Here’s an idea for a rain gauge that is similar to the one built out of a graduated cylinder and funnel. But, it automatically empties when full and can record the number of times it fills. We’ll give you some ideas of how you might build it. You can work out the details and modify the plan as you see fit.

You will need a GoGo Board or similar microcontroller. Go to the GoGo Board web site for more information on this device. (Two similar devices that are commercially available are the Handy Cricket and the LEGO RCX.)

The description below will make sense once you familiarize yourself with how the GoGo Board works and how to program it.

There is a conductivity sensor at a specific height in the cylinder. Since water conducts electricity and air does not, the GoGo Board can read when water reaches the level of the sensor. The conductivity sensor is just a pair of wires with a small separation between them.

Programming the GoGo Board

You will need to program the GoGo Board so that the motor and sensor interact with each other. When the water level reaches the sensor, the motor turns on and opens the valve. Once the water drains out, the valve is closed.

You can write the program to allow enough time for the water to flow out before closing it again. Another approach is to install a second conductivity sensor at the bottom of the cylinder. When that one senses that there is no more water, the valve can be shut.

The GoGo Board can also record data. It can keep track of the number of times the cylinder fills and empties. This data can be used to calculate the total rainfall from the time that the device was activated.

See what interesting modifications you can make to this design or design a completely original electronic rain gauge. Send us a report on your engineering project. We will publish your results here on the SEED web site.