Adaptive Path Fridge Alarm

Adaptive Path’s San Francisco studio had a meddlesome fridge that wouldn’t always latch when it was closed. Sometimes it would sit open for hours, spoiling our lunches, using up all the unicorn tears, burning all the panda fur oil, but worst of all, not rocking out to hit 80s music.

I took it upon myself to remedy this troubling situation, using Arduino to build a fridge alarm that would let us know when the door had been left open too long. The alarm ran flawlessly for six months, reducing the number of spoiled lunches and saving untold gallons of unicorn tears and panda fur oil!

The fridge door, outfitted with the hall effect sensor and the magnet (hidden under the tape).

The alarm uses a hall effect sensor and a neodymium magnet to sense when the refrigerator door is opened, at which point the Arduino starts counting down.

The Fridge Alarm In Situ

If the door is open for more than a minute the alarm sounds, filling the studio with smash 80s hits until the situation is addressed.

Sketches for deciphering the pins of the hall effect sensor. Sketches for figuring out the different door states, and how to move between them.

The scripts to make it happen certainly didn’t spring fully-formed from my head, and I found sketching to be an incredibly useful tool for thinking through all the different programmatic states of the fridge.

The Arduino Fridge Alarm schematic, from Fritzing.

Interested in building your own?

Download all the source files here, complete with scripts, code libraries, schematics and instructions.

Still aching for more juicy details? Read the full blog post about the fridge alarm at the Adaptive Path blog.