A hideaway cat litter box is a great way to make your apartment look like a residence for adults instead of crazy cat ladies. A hidden litter box in a cabinet, under a sink, or built in to some other furniture does a lot for appearances, but what about the smell? Here's how you can exploit the power of baking soda and embedded computers to keep your apartment fresh-smelling without disturbing your cat during his or her "quiet time."
What you'll need:
An Arduino-compatible embedded microcontroller (I used the Kameduino and Chibiduino from Brown Dog Gadgets: http://www.browndoggadgets.com/store/arduinocompatible/
) and the Arduino IDE from http://arduino.cc/en/Main/Software
A 6-12 volt wall wart, or a 9 volt battery
A DC case fan, 80mm or so, 5-12 volts
A TIP120 "Darlington" NPN transistor (available at your local components drawer)
Three resistors - 220 ohm and two 1000 ohm
A "matched set" of an IR emitter and IR phototransistor (I got mine from Sparkfun: http://www.sparkfun.com/products/241
A box of baking soda, ideally the "fridge and freezer" kind with the ventilation panels on the side
Some "poster tack" sticky mounting putty
Some rubber bands
You'll need a soldering iron and some solder. A solderless breadboard is a great tool for prototyping circuits without making permanent connections. Let's get started.