Saturday, June 16, 2012

DIY Automatic Chicken Door

Where I live, chickens generally need to be closed into a predator-proof coop at night. Then they need to be let out in the morning. This can be a tedious chore and hazardous to the chickens if forgotten.

I wanted to automate this process so the coop door closes up in the evening and opens in the morning without any manual intervention. Here it is in operation from the outside:

This basic design for the circuit comes from this guy.

However I did build a printed circuit board with some more advanced features, such as the ability to raise/lower the door with a switch in a sort of "manual mode", as well as regulated battery charging. Also I built in a battery and power disconnect switch in case the thing goes haywire during testing.

The premise is to sacrifice a cheap cordless electric screwdriver to perform the lifting/lowering and to use a motor-reversing relay and some limit switches as the brains. The unit basically opens the door when AC power is applied and then closes it when AC power is switched off. The schedule for when this occurs is provided by a cheap holiday light timer in my case, however it could be a light swith is one used a switched outlet, etc.

Here is the cordless screwdriver taken apart with the battery and directional switch. The switch is can actually be used for this project if the manual up/down feature is desired.The important part to save here is the battery and the motor unit. I disconnected the wires leaving a little extra so I could crimp on spade terminals.

The screwdriver attachment is glued into a piece of wood which is glued into an old plastic wire spool, with a length of rope attached. The round wood piece was made using a hole saw that was close to the same size to give a plug. Then the screwdriver bit as hammered and superglued into place. I spun the plug on a drill and sanded it until it fit the plastic spool tightly. Then I inserted it into the spool and glued it in place. I drilled a hole in the side of spool to feed the rope through and keep it anchored.

The door I originally had on the coop didn't slide very well in its tracks, especially when the weather changed - the wood in the door frame would swell and bind the door making it difficult to open/close. So I built a new door with wider channels that wouldn't bind.

The door is very simple to build, it is made from 1x4 pine. It consists of a inner box with a dado to act as a track for the cutting board. Then the side facing out is trimmed with 1x4s to give a nice look and act as a flange to install in the coop wall. It is glued and tacked together with a brad nailer.

The cutting board can slide up and down in the track which is 1/2" wide. The cutting board is only 3/8" so this prevents binding. The cutting board is some sort of plastic so it doesn't warp at all. It is 12" x 18", but this is really much larger than needed for the chickens I have. Two chickens can fit through the door at once. Some larger breeds may need it though.

I gave the door a  coat of exterior primer from a spray can. Then I brushed on a coat of latex semigloss white, which is what I had flying around. The only critical part is to avoid runs of paint in the channel so the door will not have risk of binding in its track.

I cut the caulkng with a knife and ripped out my old door as shown here. I found a ant nest underneath it. This door was held on with a few nails that I had painted over. The hole in the side of the coop need only be slightly larger than the internal box so that it can poke through and the flange will lay flush.

 The new door is built to the same size so it drops into place. I nailed and re-caulked it. One other thing I had done with this door was angle the bottom piece of wood so water will tend to run out instead of in if it rains. I had considered building a small roof for the door to keep out all rain but it is not really needed. 

Then I reattached my ramp with old hinges. A ramp really isn't required on a coop as the chickens can typically jump up onto the ledge of the door with ease. But I have one anyways. Sometimes the chickens hang out under the ramp during inclement weather, or if dustbathing.

The mechanism inside the coop to open and close the door. The powered screwdriver is attached to a piece of wood and then to the coop wall with screws.There is a second track assembly that sits above the door which has the limit switches.  It is built identically to the door but is thinner and has no trim on the front. The limit switches are bypassed with capacitors to cut down on the amount of sparking when a contact is broken, since they carry the full amount of current form the motor, which is well beyond their DC rating.

 The door raises and lowers perfectly. It's fairly loud but the chickens don't seem to mind it at all. 


Don Crowley said...

Wgat a fantastic design. Could you tell me how to made the circuit board or where I can get one? I spent most of the day so far watching your videos. I have to make this auto chicken door opener, but I don't know jack about electronics ( yet).

You are an interesting fellow

Eztoolhub said...

Good sharing of DIY Automatic Chicken Door. Great blog. Your blog is interesting and so informative. Wait for your next blog post. Thanks for sharing with us. But i have not seen your video clip. pls fix it.