A perfect project for those too lazy to walk down to the basement to empty their dehumidifier… or who forget to give their in-laws a gift on the holidays.
This winter, Zachary J. Fields went home to visit his family, but neglected to buy a present for his in-laws for Christmas. After they asked him to go to the basement and empty the dehumidifier, he decided that instead of just doing the task once, he’d make a device that would do it automatically for them.
To accomplish this task, he used an Arduino Uno (ATmega328) to control a water pump via a relay. For water sensing, he employed two pairs of bare electrical wire. When each pair of wire is immersed, it conducts electricity from one lead to another. Unfortunately, water is a fairly poor conductor of electricity, so to compensate for this, each signal is amplified by a Darlington transistor pair before it is input into the Arduino.
Each pair of wire is set up on top of each other (in a nice braided configuration) so that water level can be read as “full” when both sensors are made, and “empty” when both are off. This allows the pump to start at the full level, then cut off when water is below the lower sensor. This is important so that the pump doesn’t suck air for a long time, possibly damaging components and wasting electricity.
If you’re tired of walking down to the basement to empty your dehumidifier, then you’ll probably want to take a look at this project.
Atmel | Bits & Pieces 