Our New Year’s resolution last year was to try to have a life outside of farming. So when some friends we were visiting in town invited us to stay for dinner we jumped at the opportunity.

“What about your chickens?” they asked.

“The hens will be okay,” I replied. “We’ll close up their coop when we get home. It won’t be too long after dark. Besides, I’m sick and tired of being married to that chicken coop!”

I wouldn’t have been too upset if the coyote that attacked that night had taken only one bird. A small price to pay for our evening out. But instead, it killed eight hens and had begun eating one when the headlights of our approaching car scared it away.

We raise a small flock of laying hens in a valley full of predators. Owls, hawks, raccoons, coyotes, weasels, foxes, skunks, and stray dogs all have a taste for our hens or their eggs. The only way for us to keep our girls safe is a complete lockdown from dusk until dawn.
During the day our hens are free to roam. They clean a field of insects and weed seeds while tilling and fertilizing and produce a high value crop of delicious eggs. We contain their range with portable electric poultry net fencing and rotate them between fields of vegetable crop residues, cover crops, and grass/clover pChicsture. As long as they have adequate food the fence contains them without being energized. We do energize it when the hens are adjacent to a field of succulent lettuce!

Mobile chicken coops allow us to move the hens where we want them. Our coops are made from the cheapest thing we could find – horse trailers. When a trailer becomes unsafe for the transport of a horse it loses value. We picked up a four-horse trailer with a rusted roof and rotten floor for free.

Our first two-horse trailer with a good floor and new tires cost $100. We added a tarp on the rusted roof to keep the rain out and chicken wire over the open areas to keep predators out. Next we built plywood lay boxes and attached them above the fenders so that eggs could be collected from outside the trailer. We set roosts high up in the trailer and built a 1 square foot sheet metal door for the hens to go in and out. This mobile coop cost under $150, housed 50 hens, and worked beautifully – except that we had to open and close the door like clockwork.

I was lamenting the fact that I was married to a chicken coop one day while talking with my agricultural engineer father-in-law. I mentioned that someday I wanted to automate the door and divorce myself from that darn chicken coop. It didn’t take long for him to draw up a simple circuit while I found a linear actuator to open and close the door.

Thanks to the millions of channel surfers addicted to their satellite TVs, there is a good supply of cheap, weatherproof linear actuators used to tune satellite dishes. The Rick’s Satellite website lead me to a 36 volt linear actuator that cost $59.50 including shipping. Running the linear actuator at 12 volts slows it down, giving the straggler hens more time to get inside while the door is closing (1.5 minutes).

The 12 volt power supply on our first coop consisted of a used car battery and a small solar panel salvaged off a boat. It was cheap and worked reliably. A small 12 volt/12 amp-hour sealed lead-acid battery and a 15 volt/13 watt solar panel provide ample power and are cost effective. Both are available from Real Goods and Radio Shack. If you live in a cloudy area you may want to opt for a deep-cycle RV/marine battery with more amp-hours and a larger solar panel. Contact Real Goods for help in sizing a power system to meet your needs.

The controlling circuit is shown in the diagram on the next page The components, part numbers, and suppliers are listed in the chart beside it.

As it gets dark the resistance of the photoconducting cell (PC1) goes up, causing current to flow into the transistor (T1). The transistor amplifies this weak current through the relay coil (C1) turning on the motor (M) of the linear actuator in the extension (closing) mode. The linear actuator’s adjustable internal limit switch (LS1) opens upon closing of the door, causing the motor (M) to stop and the light emitting diode (LED) to illuminate, signaling that the door has closed. A glance from my home on the hill reveals a faint red glow in the darkness, reassuring me that the coop has power and the door has closed properly

As it gets light the resistance of the photoconducting cell (PC1) goes down and current ceases to flow into the transistor (T1). The diode (D1) ensures that the transistor turns off. With the transistor (T1) off, the relay coil (C1) returns to its normally open position, which reverses the current through the linear actuator, causing it to retract (open). The linear actuator’s adjustable internal limit switch (LS2) opens upon opening of the door, causing the motor (M) to stop.

In our sunny California climate the coop has performed almost flawlessly. There have been a few cloudy and dark days when the door closed a little earlier than usual, leaving a few hens outside for the night. Also on very warm evenings a few hens prefer to stay out until after dark, missing closing time at dusk.

To deal with these problems, we replaced the relay (C1) with an adjustable time delay relay so that the door closes a pre-set time after the photoconductive cell tells it to.

Although the time delay relay adds about $17 to the cost and draws twice as much power, it gives the system flexibility to adjust to seasonal and climatic conditions.

The circuit is straightforward to assemble. If you’ve never soldered electronic components from a circuit diagram find someone in your community to do it for you. I soldered components on a small general-purpose printed circuit board (available from Radio Shack) and mounted it along with the relay in its socket, the linear actuator, and the battery in a sheet metal housing with a plexiglass cover to let in light. Mounting the photoconducting cell on the roof of the coop would give it full exposure to the sun and simplify the housing needed to protect the electronic components and battery. The Light Emitting Diode (LED) and resistor (R2) must be soldered across the limit switch (LS1) within the housing of the linear actuator and mounted on the coop where it is easily visible. I used a 12V LED from Radio Shack that came with an internal resistor in a ready to mount housing.

I also installed a switch (S1) in order to manually disable the coop door. The night before I plan to move the chicken coop, I disable the door after dark once it has closed. First thing in the morning I move the coop while the hens are still inside and re-enable the door. In this way I can relocate the hens to a new field easily and without them losing their coop.

All told the automatic chicken coop door costs about $250 to build. A cheap divorce by California standards and money well spent towards sanity in the insane world of farming.

Ron Skinner farms with his wife, Jenn, in the Huasna Valley on the California Central Coast. He can be reached at huasna4@tcsn.net.