this is an example of a very simple water sensing circuit that is in an Altoid mini tin. Very common circuit, but the Altoid mini fits a 9v battery so well, i couldn't resist. Of course make your leads longer to suit, this length was simply to test.
The way the circuit works is through the changing of resistance when the two leads are submerged. When a dry condition is read, it's simply an open circuit, but when submerged, the conductivity of the water closes the circuit, turning the led on.
Step 1: The Parts
The nice thing about this project is that you only need a few items and a few minutes to be up and running.
- Altoid mini tin
- led trim housing (optional)
- 9v battery
- battery leads
- wire (determined by the length of leads required)
- electrical tape (did a rough tape up with a piece of plastic between the wires just to keep them apart for the test unit)
Step 2: The Wiring Schematic
Step 3: The Final Product
the first photo shows the state of the led when the leads are dry. the second, when the leads are placed into water.
This simple project took only a couple of minutes to make, but is very effective.