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!)
Could I get a description or photo please of how to rig up the RF choke with the ST01C? I’ve ordered the timer from a US ebay seller after not being able to find an electrical wholesaler locally who’d even heard of Intermatic!
And any advice on how powerful a solar panel to use would be appreciated…
Assuming one up, one down per day and negligible else, that’s say 1 minute at say 4Amps, ~0.08Ah. Call it 0.1Ah. Three hours of effective sunlight (winter, foggy morning/cloudy day) at 50mA would be 0.15Ah – enough to make up for the losses in charging. 50mA at 12V = 0.6W solar panel needed?
Funny thing is that a 5W panel is a very similar price to the 30-100mA type “car battery maintainer” type panels. Any lessons already learnt on this would be appreciated.
Leon
Leon,
I’m sure that Chris will chime in on the details of what Intermatic sent him on chokes. But the connection is quite simple. It is in series with the wire that goes to the antenna’s trigger. However, I took it one more step. I figure that I might as well protect the both the input and the output of the timer as well. I am a Ham radio operator and my antenna system is very near the coop. From past experiences when it was near my house, my RF signal can have the capability to “get into things”.
If you have a Radio Shack store near by, you can get a couple of chokes for $1.39 each. Here is a link. You should be able to find them easily from other sources as well.
http://www.radioshack.com/product/index.jsp?productId=2103978
On the ST01 timer, you will only be dealing with two wires.The black and blue. Because it is basically a simple on off switch, it does not matter which color goes where. So if you choose to use RF choke perfection, simply place them in series directly on the switch’s wires.
As far as your charging calculations go, looks like you got the math down good. But I’m weak when it comes to solar panel expectations. I will pose your question to my Ham radio electronic gurus.
I will repond more in a day or two, but basically the choke should be put as close to the motor to be as effective as possible,also, not knowing the exacts about this choke, because it is sealed in a heat tape set up, it appears to be several things on a small pc board, they also said it would work with ac or dc and any voltage you were using at the motor.
I am actually traveling at the moment, hense the delay in response, but after arriving back home in a few days I will check the choke closer and perhaps post some pics…………. Chris
Hey Chris,
Hope its a pleasure trip, not that “W” word
Anyway, from an electronics viewpoint and rule, the most efficient place to install a choke or any suppression device is as close as possible to the device that you are protecting. But if you are just isolating the timer from the motor, I would see no harm with placing it near the motor. BUT, if you want to protect the timer from ANY and ALL stray RFI that may get induced into the timer (strong radio waves or other noise transmitted RF) you are always better off to place the suppression device right at the device you want to protect (the timer). I could get into more detail but I will stop here
Bob
Hi Guys,
Well I rigged up the ST01C with an inductor from my parts bin – about 1.5mm varnished copper wire wrapped maybe 30-40 times round an iron ring. Soldered it to the black lead from the timer and it definitely didn’t do the trick! I had the timer resetting every single time the antenna pulled closed.
Chris, that RadioShack unit you linked me to – is that what you’re using?? Doesn’t look like it’ll take 3 or 4A of current for 10-20s while the door moves.
Cheers,
Leon
Hi Leon,
I sent you the link to the Radio Shack chokes.
I think you are connecting things incorrectly. I say that because you are concerned about the 3- 4 amps. This tells me that you may have the timer switching the antenna’s motor, not the the trigger? You need to connect the antenna’s red and black leads DIRECTLY to your power source and leave it there. The only thing that the timer controls is the antenna’s trigger circuit. This requires micro amps to do. Therefore a choke as the one in the RS link will be more than large enough.
Bob
Thanks Bob. I think I’ve got it wired properly, but yes, I was still (strangely) thinking that I needed to switch the 3-4A with the timer rather than just the high/low sense wire. Cheers!
Leon