So you let them out at 6AM and back in at 8:30PM, and the door should be open between those hours. Do they change their schedule or you yours depending on the time of year or do you want it open for those same 14.5hrs every day all year around? I suppose a simple manual adjustment of the time once every month or two will keep you from worrying about a real-time-clock. I suspect the letting 'em out is not an issue as the door will be open all day. The closing of the door is the transition to consider closely. How will you tell them "I'm closing the door hurry on in now!" You know their behavior, are they waiting at the door when you arrive or do they come only when you show up. Don't know how smart they are, but maybe they can be conditioned to go in when a sound, tone or some sort, is played. A door that closes 1 degree/sec will give them 90 seconds to whoop their asses in there and it shouldn't scramble any eggs!