I made this rather simple circuit to give some coding guidance to a friend starting with Arduino. It is a part of a more complex project he want to make that controls the fill up and level of multiple water tank network placed at various places in a building. Basically this little project demostrates how to use push buttons as inputs, LEDs as outputs, eeprom storage and conditional commands.

So this little prototype does the following:

- Indicates 3 water levels  (min-mid-max) using 3 LEDs. (Normally an LCD display is used).

- To read the level there are 3 buttons. One for each level. (Normally you would use a magnetic floating element that activates 3 reed  sensors.
The floater should terminate its travel in front of min and max reed sensor).

- When MAX level is reached pump signal (led pin 13) is deactivated. Water pump is reactivated when water drops back to MID level.

- The circuit also features an Auto/Manual operation button and each corresponding warning light LED.
At AUTO mode the pump stops when maximum water level is reached. Warning LED is off.
At MANUAL mode the maximum level check is overridden and the water pump keeps working. Warning LED is ON.
AUTO/MAN status can be toggled at any water level.

Bellow you can see the circuit I made on breadboard recreated visually with the help of the very nice and helpful Fritzing project.

Here is the video of the circuit above in real operation.

Download code