Picture of Build a cat litter box fan with Arduino
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.
RichM1 made it!10 months ago

Awesome thank you!

I made a slight change, but essentially using the same schematic. I'm planning on putting my XBox and Satellite receiver in a cupboard, but obviously want to keep things cool (rather than not stinky!) so swapped out the break beam with a DHT11 temperature / humidity sensor to power a fan and keep the air circulating above 30 celcius.

I used a 2n3904 NPN transistor (as that's what I have kicking about without breaking a sweat) but it works just fine.

Now to stick the whole shebang into a SFF arduino board and dump it in the cupboard. Power will be supplied from the USB port on XBox with a 12volt wall wart for the fan.

Photo 26-10-2014 19 32 19.jpg
5 stars for originality,
Haha, awesome! Does your cat open the cabinet to get in or do you keep it open for him?
jpayne6 (author)  jessyratfink3 years ago
There's a little prop to hold the cabinet door open - an unsharpened pencil cemented into place with epoxy putty. The rubber eraser end keeps it from banging and gouging the wood.
Ah! Very smart. I was wondering about the banging. My cats like to go in the kitchen cabinets and it is always a very loud affair. :P
What a lucky kitty!