Automatic coop door

A few months ago I started working on an automatic coop door. I looked at a lot of designs and settled on one that used an electric screwdriver. I have no knowledge of electronics other than the general circuit stuff so this was quite a learning experience with a lot of reading done when things weren't working as they were supposed to. I used 2 limit switches, 1 double pole double throw (DPDT) relay (and I actually know what that is now!) and the parts from the screwdriver.

Basically the way it works is you plug in the screwdriver which charges the batteries. It is important to have those two power sources because you need a source of power to raise the door and another source to lower it. The limit switches stop the door at the top and the bottom. 

A limit switch

The power source is plugged in to a timer. When there is power to the screwdriver it goes in one direction, when there is no power it goes in the other direction, thanks to the DPDT relay.

I got the electronics working when we were still in the other house but had a hard time finding something to put on the screwdriver to act as a spool. I tried an empty thread spool but it caused the door to go too quickly. I tried a smaller one which helped with the speed but the rope would go over it and jam the screwdriver. I bought a 2" screwdriver bit and put a round piece of wood on it near the screwdriver to stop the rope from binding up. That part worked great. The biggest issue was that the door wouldn't always hit the limit switch at the bottom. This caused the door to lift back up and then jam up the screwdriver when it hit the top. This happened a couple times and I had a hell of a time getting the rope undone. If this had happened without me sitting there to turn off the screwdriver it would've easily burnt the motor. I knew this was happening because the frame would flex but I was really hoping it worked when everything was installed on the coop door. Next step was to install it on the coop. I first screwed it into place and made sure everything worked ok before cutting a hole in the door that I wouldn't be able to easily fix if it didn't. It worked perfectly. The door slid up and down just as it should. so I used a sawzall and cut a hole in the door. I setup the timer and right at 9:00 it shut and was open the next morning when I got up. It has been working perfectly the last few days. It is such a relief to not feel guilty about the chickens in the morning when I want to stay in bed, and like tonight when it was pouring rain around 9, it was nice to not have to go shut them up. 

Below is the near finished product. This was before I had figured out the spool. This one you can see this was the first larger spool I started with. I was originally using the small screwdriver bit that came with the screwdriver. The nice thing about this was it popped out of the screwdriver easily so when it jammed I could easily fix it. 

The white tracks were from a drawer and purchased for $2 at our local ReStore. The screwdriver was $10 at harbor freight. The cutting board was $10 at walmart but came with 2 other sizes that we use in the kitchen so we'll say $3 for the one. The limit switches were around $2ea (don't remember the exact price). The DPDT relay was $4. The wood was just scraps around the house. Overall it cost me roughly $25. Not bad considering ones you buy prefab cost $100+

Best thing ever!

The nearly finished product