Linear actuator chicken door :)

Discussion in 'Coop & Run - Design, Construction, & Maintenance' started by totalloser, Mar 14, 2018.

  1. totalloser

    totalloser In the Brooder

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    I looked at a lot of door designs, and though this may have been done before, this is how I did it, and think it's worthy of consideration. ;)

    My experience is that timers are close to useless as far as reliability, so I chose to use a photoswitch to operate a small 12v DPDT (dual pole dual transfer) relay which reverses the polarity on a linear actuator. The linear actuator has built in limit switches (I "think" most do) so the installation is fairly simple, and durable.

    One bummer is that almost all photoswitches are designed for streetlights, so they are "on" at night, and thus the relay is live all night. However, the switch and relay draw very little juice. I am using a 12v solar with a puny mppt controller, but there are plenty of other ways to make this work.

    Also of note: since the photoswitch is "on" at night, this enables a 12v LED motion light so it doesn't run all day for chicken antics.

    Photoswitch $10 Relay $5 Linear actuator $25 Other stuff can be done other ways, but I will note that the battery would be the costly part, and your *old* car battery with a foot in the grave is more than adequate to run these puny loads.

    Oh, and the astute viewer will note that it's not completely hooked up. That's just because it was the pic I had handy.
     

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    Last edited: Mar 14, 2018
  2. cavemanrich

    cavemanrich Crossing the Road

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    Welcome ,,,,,,, :welcome
    It would be good If you would add links to the items you purchased. It also would help those not very familiar with electronics if you could sketch a wiring diagram on paper and post that pix.
    WISHING YOU BEST,,,,,, :highfive:
     
  3. jthornton

    jthornton Crowing

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    I would add a delay timer to the photocell so the door does not close until dusk.

    JT
     
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  4. totalloser

    totalloser In the Brooder

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    The photoswitch is adjustable for sensitivity. It comes "on" at dusk, which operates the relay to close the door. In the morning, at dawn, the photoswitch goes "off" which de-energizes the relay which switches to the other set of contacts that have opposite polarity, and thus the door opens. The electronics in the photoswitch have a window of operation between phases, so it doesn't kick on and off for clouds at dawn and dusk's tipping point. It's a commercial component that normally operates street lights.

    As far as a timer? Not needed unless you want to do something other than morning and night. The photoswitch is adjustable for sensitivity. FIWW it is done and functioning as designed. I just didn't have a finished pic handy when my wife suggested I post it.

    12v Photoswitches pop right up with any E-bay or Amazon search, as do 12v DPDT relays. Same with linear actuators- the specifications for mine are 12v motor, 400mm travel (just under 16").

    DPDT relay has 8 tabs. Two for the coil, four for the stationary contacts, two for the switched contacts.

    Power flows to the photoswitch, then to the relay coil.

    The 4 stationary contacts have opposite polarity (+- then -+) to switch the direction of the motor, and the "switched" contacts go to the actuator.

    Kinda hillbilly, but I just crimped two wires into each connector to limit the mess and hopscotch across the relay.

    If you get the polarity backwards on the actuator, all you have to do is swap the linear actuator wires at the relay.

    The key here, is that this system uses inherently reliable, off the shelf components. Which are basically designed to do what I am doing with them. I was REALLY loathe to use any timers due to years of headaches in my greenhouses. Never did find a reliable one, and wound up swapping in "line voltage" cooling thermostats and humidistats.

    I'll sketch something out in a minute, and take a wiring pic next time I'm over at the coop.

    OK, kinda sloppy, but I was trying to illustrate the wiring harness arrangement rather than a less readable "theory" diagram. And of course, different components may have different layouts. Use the diagram on the components you buy.
     

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    Last edited: Mar 16, 2018
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  5. totalloser

    totalloser In the Brooder

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    Snapped a pic. Wiring will be further tidied when I mount the LED varmint illuminator, which just showed up. It gets plumbed into the photoswitch circuit so they were gonna get nipped and re-crimped anyhow.

    However, though it wasn't the point of the thread I ran into my first two problems. First rain splatters from the battery mount and photoswitch, and caused the door to swell *just* enough to start binding.

    Three further notes:

    No color coding. Why? Because it's what I had laying around in smaller gauge wire.

    Plumbed into the battery circuit rather than "load" on the MPPT. Why? Because this battery is iffy enough that the MPPT thinks it's dead, and it's half right! :D

    No fuse box. Why? I know I've got something bonking around that would work, but didn't spot it readily. And I don't mind barbecued chicken. :p
     

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  6. jthornton

    jthornton Crowing

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    Electricity doesn't care what color the wire is...

    JT
     
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  7. totalloser

    totalloser In the Brooder

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    That was my thought, but it wasn't meant for an audience originally. It does make it confusing to in the pic though.

    With the photoswitch adjusted most sensitive, facing East and shaded by trees and the "roof" it shut the door shut at 7:17PM Pacific today. There is plenty of adjustment to close it later, but it seems about right. It is possible to get more adjustment to close sooner by shading the sensor a little, but I think I'm happy with it as is.

    Managed to wiggle the thing into its final resting place without destroying it. The "plan" is to run the chickens in one half of the garden, split by fence with poles over pounded in concrete stakes and swap them every year.
     

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  8. archeryrob

    archeryrob Chirping

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    What actuator did you use? I can't find one that cheap.
     
  9. gpro

    gpro Hatching

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    Why is there only one wire going to both leads of the actuator? Shouldn't there be both positive and negative going to it to activate the motor?

    I have found another schematic with the same component but wired differently. Disregards the limit switches as the actuator has them built-in. haven't tried it yet as I'm waiting for the parts.

    Has anyone applied this wiring?
     

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    Last edited: Sep 29, 2018
  10. totalloser

    totalloser In the Brooder

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    Prices appear to have gone up on actuators ($35-$40 with a quick glance on ebay), but to be clear- it was $25, not $5. I can see how that would be confusing.

    Linear actuator has two wires that go to the switched end. When the relay operates, the polarity (positive negative) swaps. The actuator has built in limit switches, so it runs until it reaches the end of it's stroke and then stops until switched again.

    But I came back to update how this has worked out :p and save some time for anyone else running such a setup.

    First off, the actuator system works great, but I put too much faith in the coop protecting the chickens from predators. Lost five to foxes who climbed the fence- the last one waited around all night (game cam pics) for the buffet door to open. I frantically put up a nice hot electric fence, (and took other atritive measures) but a few of the chickens associated the door with the fox and refused to go in at night despite great attempts at persuasion. Eventually they decided they liked the night light (15w led flood) and all but one Australorp go in. I currently still have 3 Barred Rocks, 2 Australorp, 2 Rhode Island Reds.

    I probably should have noted for the unwary- the MPPT controller shown is sort of a scam. They are listed routinely as 10 or 20 amp- but that's just what it will pass to the load from the battery. These controllers are really only 3A. Which worked fine for my 50w panel, but I quickly added a real battery, better charge controller and a 150w monocrystalline panel to run various other things.

    BEWARE!!! There are less than enlightened folks sharing that they don't know how to hook up electric fences. I came across some of these posts. If the hot wire is not isolated, and can arc to metal, or is *connected* to metal, it may very well start a fire and burn down your neighborhood. This literally happened this summer the next town over from me. Blades of grass are highly unlikely to do this, but an arc to metal is hot enough to get light flashy fuels burning. Isolate the electricity from conductive materials. Modern high impedance fence controllers are not as dangerous, but they still must be hooked up correctly!

    My takeaway? I can see why the foxes gave up. 1 Joule (delivered) makes ya see stars! And they seem to like BBQ just enough to be foolish. I would have gone bigger on the solar in the first place to guarantee minimal cycling of the battery and cover unforeseen loads. I also would NOT have used cheapo plastic fencing to separate the chickens from the garden. I set it up so that they could trade sides- which seems to work great. The chickens do all the weeding and fertilizing while the other side is growing. Except they nip the plastic fencing and make a big mess when they get on the other side. Having said that, they apparently are capable of learning they don't like the garden hose! :D I think I've learned why they it's called chicken wire, and that plastic stuff is *not* called chicken wire. :p

    And I'm going up in scale. 30x48 is going to be 78x90 and 20-24 chickens if the excavator and I can quit breaking each other before spring.
     

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    Last edited: Oct 16, 2018
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