One of our garage door actuators gave up the ghost and rather than spend $35 on another one, I decided this was a job for my Raspberry Pi. That way I could open it with my iPhone.

Of course, this has been done before (https://learn.adafruit.com/raspberry-pi-garage-door-opener/intro and http://www.instructables.com/id/Raspberry-Pi-Garage-Door-Opener/). This version differs in the following ways:

1. Uses Node.js instead of python/apache.

2. Does NOT (yet) provide feedback as to whether the door is presently open or shut. I use my eyeballs for that :).

3. Does not use a relay shield or relay controller--I brew my own. This is a great exercise for learning about relays and transistors. (Note: the voltage being controlled here is quite low--in fact so low, I could have probably switched it with just the transistor alone. I make no guarantees about the suitability of this circuit for higher voltages.)