Automatic Chicken Door Opener
In this instructables tutorial I will walk you through the steps and parts necessary to create an automatic chicken door opener from common parts that can be purchased from many retailers. The parts and tools used are all affordable and easy to aquire.
● Irrigation timer with at least 2 stations
● Relay board with 4 channels
● 24VAC to 12VDC converter
● 12VDC linear actuator (2-4” stroke)
● 12VDC lead acid battery
● 2 bridge rectifiers
● 2 1uf capacitor
● Enclosure for the board
● Wired cutters
● Screw drivers
● Soldering iron
● (optional laser cutter for enclosure)
What is happening:
We will be using a standard AC garden timer to control a linear actuator. In this case we are using the linear actuator to open and close a door. The relay board is used to reverse the polarity of the DC power required to open or close the door. Lastly, a battery is used to provide the current required to operate the linear actuator.
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Step 1: Step 1 - Connecting the Power
Lay your timer on a table, we will be connecting the
power leads to the timers AC input terminals, and connect the ac power cord to it .
Connect the power supply to the timer terminals (Please resist the urge to plug in into the wall). Connect separate set of wires to the AC input terminals on the timer to the AC/DC converter. This will power the relay board and keep the battery charged. So lets do it. Connect wires to the Positive and negative terminals of the AC/DC converter connect those wires to the corresponding positive and negative terminals of the battery. From there connect more wire to the battery and connect them to the correct DC IN terminals on your relay board.
Step 2: Step 2 - Bridge Rectifier Modifications
Bridge rectifiers have two AC legs denoted by the squiggly lines on the cap that look like a tilde “~” symbol. Remove one of the AC input legs on each rectifier.
Also remove the negative leg on the rectifier. It too is not needed. What you should be left with is one AC leg, and one positive leg. See figure below.
Attach the remaining AC leg of the rectifier to station 1 and repeat this process for station 2. Since we are using only one leg of the rectifier, we end up with the beginnings of a 12VDC signal that we can eventually use to to control the 4 channel relay board.
Step 3: Step 3 - Connect the Relays
In order to open and close the chicken door we will need a way to reverse polarity on the linear actuator. To achieve this, we will use station 1 to control the opening circuit, and station 2 to control the closing circuit.
Connect the positive leg of the rectifier from station 1 on your timer with a length of wire that is long enough to reach your first set of relays. Connect that wire to the input side of both relays 1 and 2. Then connect the positive side of one of your 1uF capacitors to relays 1 and 2. Note: the capacitors are often polarized and indicated with a stripe with a minus symbol on the negative side. Repeat this for station 2 for relays 3 and 4 with the capacitor. Now you are left with the negative side of your capacitor. Connect a wire from both capacitors and connect it to the negative connector on the relay board.
Step 4: Step 4 - Powering the Motors and Reversing Polarity
Our relays are working now on to power the motor. For this we will start with the positive side. Connect another wire that is sufficient for your motor to the positive side of the battery. Take that to the “Com” (common) side of relay 1 and 4. Do the same for the the negative to relay 2 and 3. Here’s the part that’s counter intuitive. Connect together one of the wires from the motor to the “NO” (normally Open) terminal of relay 1(pos) and relay 3 (neg) next connect together the other wire from the motor the “NO” (normally Open) terminal of relay 2(neg) and relay 4 (pos). Since you will only be turning on relay 1 and 2 at the same time and 3 and 4 at the other time you will create the polarity reversals
Step 5: Step 5 - Connect the Linear Actuator
In order to complete this project we need to connect the linear actuator to the door. If yours is the usual small chicken door just large enough for, interestingly, a chicken. For that you will need an actuator with a stroke length of 2 to 4 inches with limit switches. The limit switches stop the motor from over driving in or out. These can be easily found on EBAY. You will need to adjust the position so that when the door is closed the actuator is at full extension and when it is open the actuator will be at full retraction.
Step 6: Step 6 - Program and Test
After you have assembled to the parts you can program your timer to open and close. I use station 1 to program the open phase and station 2 to close the door. It usually takes less than 1 minute to close the door so you will only need to program your timer to run just long enough to accomplish this task. Run it a few times and then figure out what time you want to let your modern dinosaurs out and what time they go back in. Make sure to leave time to get the stragglers at night. I program mine to close 1 hour after sunset. Always make sure your door is operating properly. optionally you can add door switches in case you have a chicken in the door way to keep them from getting squished.
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