Pi-Rex is a bark activated door opening system for pet dogs
David Hunt was looking for a solution to let his dog in and out of the house without disturbing his own sleep in the morning and night time. So he came up with a bark activated door opening system that automatically opens the door when the dog barks. This DIY project is in a way educational project that makes use of Raspberry Pi, noise detector circuit, motor driver PCB circuit and other electronic components. David didn’t make use of any cameras for this project as it would increase the project cost and on top of it he wanted it to be a voice activated system rather than visually activated system. David calls this innovative DIY as Pi-Rex and it surely makes his dog happy as he can wander outside in the woods or come back in anytime.
# According to David Hunt
It involves a bark detector (noise detector circuit) wired to the input of the Raspberry Pi so that it can detect the barks. A motor driver circuit to drive the actuator that unlocks the door, and a weight/pulley system that swings the door open when it’s unlocked.
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.