For everyone in the world whose heart has not blackened and shriveled beyond repair, nothing boosts your mood quite like a new family addition in the form of a dog. That is, until you have to wake up at the crack of dawn to let that needy, opposable-thumbless mutt out. But new dog owner and Raspberry Pi enthusiast David Hunt has rigged himself up a highly creative solution: a door that automatically unlocks at your dog's bark—or as he's dubbed it, Pi-Rex.

A Dog Owner Rigged His Door So That It Unlocks With a Bark

Trying to make this DIY doggy solution as easy as possible, Hunt eschewed any potentially expensive camera equipment in favor of a cheaper noise detector circuit, which was aided by the attached Raspberry Pi and motor driver PCB circuit. Once the tiny computer detects the bark, the circuit drives the actuator to unlock the door, and a simple pulley system swings the door open to reveal the giant bathroom that is the world.

Hunt describes the process:

I picked up the audio detection circuit in Maplin as a DIY kit for €9.99, the kind of ones where you get all the components and a PCB in a bag, and solder them all together. It took about 30 minutes, but worked perfectly, I could bark, and the LED’s would light as I barked. My family thought I was gone mad when they heard me making dog noises in my workshop.

A Raspberry Pi in the centre, a motor driver PCB to the left. I used this because it easily allows me to send 12 volts to the actuator in either polarity, for pushing or pulling the door bolt. The PCB on the right is the audio detection circuit from Maplin. And at the bottom is the 12V actuator. The small veroboard PCB is just a voltage breakout with GND, +5v and +3.5v, to make the wiring easier.

All the wiring is done with dupont connectors, 0.1″ (2.54mm) pitch, just like the Raspberry Pi GPIO header. I got a crimp tool off eBay, as well as a a few dozen blank connectors and a roll of female crimps. Make cabling up this kind of project very easy, where you don’t want to solder everything into place.

A Dog Owner Rigged His Door So That It Unlocks With a Bark

So while it will certainly take some technological knowhow, the project really isn't all that complicated. Hunt even gives you all the code you need to make a Pi-Rex for your very own over at his website. Finally, Fido is free to relieve himself at will—so you can get some sleep.

A Dog Owner Rigged His Door So That It Unlocks With a Bark

[DavidHunt.com via Damn Geeky]