Auto Coop Door II – Antenna

I’ve been fascinated with automatic chicken coop doors.   My current auto coop door closer has been working like a champ for months.  I received a lot of great replies to that thread, and one of them was from a visitor named Bob.    I was so impressed with his design and pictures I asked him if I could post his comments and pictures as an article here.   I’m SUPER glad he agreed.   So, below are his words: 

Here is the automatic door I built with an automatic car antenna (click the image to see it in action). I chose the antenna method because it has a built in stop when it reaches its end in both directions. This eliminates the need of more circuitry to control “run time”.

Mine runs off a little 12v lawn tractor battery. The battery is kept up to charge with a “float” charger. The door opens and closes with a photo light sensor. The reason for the battery is so that a power failure will not cause a problem. The reason for the light sensor is so that the length of daylight does not need to be constantly adjusted on a timer. BUT, you can simplify things and use an ordinary appliance timer plugged into an AC outlet, and then use a 12v DC power supply to power the antenna.

This is just one way to use an automatic car antenna. With some imagination you could probably come up with many more designs.
As you can see the antenna is mounted upside down. The door is made from an 1\8″ ALUMINUM panel. It is light in weight but very strong. The door channels are 1/4″. I have a 3″ spacer connected to the tip of the antenna to the door. You can measure the distance you need to determine the spacing length. I used a piece of aluminum stock and tapped each side to mount it. The side on the antenna tip has a hole for the tip to set in, and then I used the tapped hole as a “set screw” to keep the tip in place. I have my tip connected towards the bottom of the door. This makes the length of the door channel a bit shorter in order to match the up and down stroke of the antenna.

Be sure to carefully measure the lengths and travel distances needed for the antenna to move up and down freely. I have heard of some discussion that the travel distance does not need to be exact because the antenna’s “auto stop” feature will sense the end travel and the motor will time out. But that will be up to you.

If you do not have some aluminum sheeting lying around, you can find some at Lowe’s or etc. Aluminum can be easily cut with your skill saw. Just make sure you have a carbide blade and wear safety goggles. Even some type of plastic sheet would work. Just keep it light and strong.

The door channels can be purchased also at Lowe’s or Home Depot.

The best price for the antenna was on-line at Beachaudio.com, but they may be out of stock. Just search the web for the least expensive “automatic antenna”. Mine was about $35.00. The antenna MUST only have three wires. (Beware of the non automatic antennas that require the user to “toggle” the antenna up and down manually). Two wires connect directly to your power source. The other wire that is not black or red, is the “up down” trigger. That is the wire that you connect to the timer or sensor circuit.

If you go with the 12V battery, the float charger can be bought at Harbor Freight Tools for under $10.00.

I have updated this article to mention that the there may be a better control system other than the night/daylight sensor that is described below. I have used this sensor for about a year. However, just recently I noticed that the control unit was sometimes “confused” in the mornings and would make the antenna move up and down erratically.  Not fun for the chickens. It was mainly due to setting the photocell too sensitive in order to stay open at night as long as possible. Please be sure to read the later posts regarding an Intermatic ST01C timer. This timer is very unique because it does not rely on household current to operate. It is also very unique because it has an “astronomical” feature which updates the internal clock when dusk and dawn occurs in your region. It is powered by a 2 year lithium battery. Below is the night/daylight photocell circuit, if you decide to want to experiment with it.

Here is the circuit.  Its pretty simple and self explanatory and would require someone that has done a little soldering in the past.

The only thing that is really not explained is the CDS photocell. One could try different types to see which works best. The one I ended up using was from a photocell variety package purchased from Radio Shack.

If you decide to go with the photocell circuit, the antenna’s power wires (red and black) must be always connected to the 12vdc power source and not be controlled by the photocell circuit.

A few thumbnails you can click on for the control box, door channel, battery / charger, photocell

On the other side of the box I have a little slider switch that makes the door close manually.

The tip spacer/connector will probably be the hardest part for a lot of people to figure out to. There plenty of ways to get that done. I had a piece of an aluminum rod that was solid. I drilled and tapped each side of it. There is a screw going through the outside of the door to one side of the rod. I drilled a hole in the rod for the antenna tip to sit in. The screw on that side of the rod is a set screw that keeps the tip in place.

(Rob Note:  A huge thanks to Bob for this great design, pics and wrtieup and for letting me post it on the site.   I know we are both looking forward to reading some of your comments!)