The automatic chicken coop door was made in April 2016 since I did not want to open the door every morning and close the door every evening. Not only could I forget, but I did not want the hassle with other daily stuff.
A few folks have made it with the car radio antenna extruding either vertical or horizontal. I chose vertical to avoid risking debris clogging the action. If you have chickens you know they are messy.
I used two 12V AC adapters to each power the "retract=open" and "extend=close" and used a single AC timer to have on during the time of day I wanted the door open and it turned off at night when allowing the other 12V AC adapter to close the door. Others found concerns with significant leakage, but the $18 radio antenna seemed to have a 5-second on or off period after which it would turn off the motor, so my configuration was not leaking measurable AC power when the door was open or closed.
I liked the spare aluminum tracks, but as usual, the more true and plumb you are the better. Next time I would replace the vinyl door with plywood, but even the vinyl kept the raccoons out.
A concern for reliability could mitigated with periodic oiling, and I had no serious concerns during a few months usage, until the raccoon got the chickens.
Video at coop-door