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Automated Greenhouse Ventilation

by:Trust&Deal Breeding Equipment     2020-03-03
In this note I will show you how I made the low budget Greenhouse ventilation system.
The climate in Estonia is quite cold, so the greenhouse is very helpful for growing tomatoes.
However, the growth of tomatoes requires relatively dry air, so the greenhouse needs ventilation.
My greenhouse is located on a plot that is not my permanent home, so no one opens and closes the windows manually every day.
My goal is: main material: the build process is mainly recorded in the image review.
The text section of each step is an overview of ideas and ideas that are not visible in the image.
The Arduino code is published on onbut, please read Step 6 for what you need to pay attention to when you reuse it.
The system has been in use for 3 summers.
So these pictures show something that has changed over time.
The longer video was made after the first iteration was ready in 2014.
During that time, there were some accidents and some parts were worn out, so in the final step, I will also introduce what I plan to redo when the next growing season comes.
Since my goal is to use a single actuator to open more than one window, I have considered it when building a greenhouse.
Two windows.
There is one at each end of the building.
When the mechanism does not pull the windows open, there are hinges on the top edge of the window and weights on the bottom edge to keep them closed.
In addition, the system needs a column next to each window to extract it.
You can make heavy duty columns with metal or other durable materials and pour some concrete to keep them up, but I made a lighter stand.
The pillars are wood. they\'re sitting at 30-40cm / 12-
16\'\' on the ground, there are some rocks around, on the other side of the window weight, there is a rope/cable that is pulled with a hook and connected to the ground.
And a window as the entrance.
There is a door section right below it.
I added a rope to the pole over there.
There is a hook at the end of the rope.
So if the window is currently closed, you can open it and hang it on the hook when you want to get into the conservatory.
The open position is not really horizontal and the door is low, so even if the window is in a ventilated position, we usually lift the window to the hook.
The walls of the greenhouse are made of old windows.
The roof is soft plastic (
Special greenhouse)
The winter is removed, otherwise the weight of the snow and the fragility caused by the cold will destroy it.
The open window was some of the old shower walls I found from the bin.
But they have no resistance to UV rays, they are scattered and I have to replace them after just two summers.
Since there is no suitable hinge around me, I use the bicycle chain to make the hinge
Happy about the opportunity to reuse (
They only work for things in the hanging position).
As mentioned in the intro, I chose an old car battery as a power source because sometimes they can be found for free.
Even if it is too bad for the car, they can keep enough energy.
But you have to find one that can still be charged.
After a period of negligence, lead-acid batteries refused to do so.
I personally made myself a \"lead-acid battery desul device\" that can bring some old batteries back to life.
But it\'s a crazy dangerous device, so I don\'t recommend it to anyone who doesn\'t have an education in the mains, or anyone who has children at home.
So, try to find a battery to charge from a regular charger.
At first, I planned to charge the car battery after a week or two, but I became lazy, which was not good for the health of the battery.
Then I added a solar cell that was able to keep charging.
I don\'t have the specs anymore, but it\'s rated at 18 V, 10 W and contains a diode.
Its physical size is 38x 22 cm/15x8 5/8 \'.
Solar panels cost me $25. ebay).
In addition to the battery and solar panels, there are car fuses in the power supply section.
I should have replaced the fuse with a smaller fuse because I used to have some wires blown but the 30 fuse didn\'t move.
I have information that 10A may be too low when the drill motor is just turned on.
So next year I\'ll try lower values like 15A to see if they stay the same in normal operation.
Use decent wires like 1.
5mm/16gw copper.
If you put the battery away from the motor, increase the thickness.
Do not use cheap \"speaker wires\" that are not copper because they will soon be corroded into nothing.
Solar panels in China also have these unreliable wires, so replace them.
And use the appropriate connector on the battery terminal.
In the long run, the crocodile clips I use are not the best.
Although I haven\'t noticed their problem yet.
Although the speedometer (
Wind speed measuring device)
Not the most relevant part of the system, I think this is a cool thing.
Here is the garbage list I used to make the speedometer: disc motor-
The one rotating the CD-
There are very few things needed for a speedometer :-
Shaft with bearing-Hall\'s sensor (
Induced magnetic field)-
The magnet triggers the sensor, so I made a speedometer with it.
The main operation is to take the motor apart and remove it from the winding of the motor.
The winding stops the rotation of the shaft together with the magnet.
However, it rotates freely when the winding disappears.
I made the speedometer \"Cup\" with some food containers \".
Choose something spherical or tapered.
I made the arm and held the Cup with aluminum plate material.
The attachment of the CD motor is by drilling holes in the \"plate\" section of the motor and using some wires in these holes.
I bend the aluminum arm so I can put the other one (slightly wider)
In the center cup, protect the motor and electronic equipment from the rain.
This has worked very well so far.
The Cup breaks down under UV light, so it is ready to be replaced after two years.
I added a small circuit to get a better signal from Arduino\'s tachometer.
The Hall sensor only causes minor fluctuations in the output voltage when the magnetic field changes polarity.
Between 2. 2 and 2. 8 volts maybe.
Reading the article with analogRead and deciding when it actually does a full up and down loop would be a challenge.
But comparator is a perfect solution.
The comparator is actually an operational amplifier that is connected in some way.
It compares two inputs and switches the output to GND or 5 v depending on which input is currently higher.
If the voltage divider is connected (potentiometer)
Set one of the inputs so that its voltage is between the minimum and maximum values of the other input fluctuation, and then basically output the binary signal.
Better yet, there is lag.
This means that when two inputs are similar to each other, it doesn\'t bounce back and forth, but waits for \"which one is higher\" to be clear before switching the output.
This means that it does not need to be abandoned in the software.
This makes the code part very simple.
You must adjust the potentiometer to where the output signal appears.
When adjusting the pan and observing the output, move the magnetic ring to get the fluctuation.
You can use a multimeter, but the LED with a resistor is easier.
I found that the output flashes six times per revolution, and if you want, you can try to calibrate the measurements of the anemometer, compared to the ready-made handheld anemometer (
About $10 on ebay).
The most striking part of the system-
Actuator for pulling windows-
Consists of the following parts: one end of the screw bar is ground into a triangle and then connected to the Chuck.
The \"box\" section needs to have a relatively smooth back wall, a drill bit motor at the top and a \"floor\" installation with a skateboard bearing that holds the bottom of the threaded rod.
The moving part is an oak tree.
I drilled 9mm holes on it and made a groove in the shape of the M8 nut around it.
Then I made a \"lid\" with a flat sheet of metal: There are 9mm holes in the middle and two screw holes.
To get that block running on the back wall of the box, I screwed some larger washers into the corner as a wheel.
The blocks and washers have been well maintained for the last 3 years.
There are some signs of wear on the back wall, but it is not yet at the end of life.
In order to connect the actual pull line to the actuator block of the wood, I made some temporary labels with holes under the bolts.
The Bolt also holds the \"nut cover\" in place.
Two pulleys are required on the top.
My original solution here is a bit fragile and unreliable, and the second version is not perfect, so it will be redone next year.
Limit switches are also required for the actuator.
Besides the sensor, I want to be careful.
Limit switch read by micro controller-
I added a pair of \"kill switches\"
The sensor is an oversized button with a sponge material cover that can relax a bit between pressing the button and pressing the button.
A wire of the drill goes through the well switch-
Therefore, if the system ignores the sensor switch, it will only disconnect the sensor switch and then click the kill switch.
Do not break the case or the motor holder or anything else.
Since I suspect the 3A motor current and the normal lever switch, I tried two different temporary switches as kill switches.
But both versions are very unreliable.
You can read more about them at the last step.
Next summer, I will buy some bulky switches that can do the job.
I have made two evaluations of the electronic part of the system.
The first version is to use a 12 v relay.
When the 12 v relay module was broken, I decided to redo the mess around the homemade Arduino board as a more permanent component.
I used Arduino Pro Mini and 5 v relay this time (
Because I can\'t get 12 V soon).
So I need to add a buck converter to get enough 5 v current for the relay.
The complete schematic is about the 5 v relay version.
The independent image of the module is version 12 v.
The relay can be triggered at a high level or at a low level.
You can also use it, just find the right place in the code.
Be careful when running the first Test, because if the direction is opposite, the limit switch on that side will not stop it.
I drew the whole system by hand and used the symbols that best fit to convey each part.
Also, there are some of my previous parts drawings that you might find helpful.
If you don\'t want to include the SD card, you can turn off the features in the code.
There are no 3 Micro SD modules compared to full size card modules.
3 v pins, but this is not used in my schematic anyway.
The code is published in.
Find the clone or download button and find download ZIP \".
It consists of multiple files that appear as tabs in the Arduino IDE.
Many connections are hard-coded and operate using a direct port instead of Digital Writing and digital reading.
This makes code execution faster.
You should pay attention to the following files (tabs)
: The following two libraries are required: 1: There are two features in the code that I have not tested because when I have time to write the code, the system has been turned off in the fall.
One is to measure and record the battery voltage.
Second, windows operation timeout.
If the motor is turned on longer than the preset time (
The assumed maximum time from the open position to the closed position, and vice versa)
The relay is then turned off.
If the limit switch is not pressed for any reason, realys will remain the same all the time.
Let me know if you test my system and find anything suspicious inside.
Note 2: The code is written for boards with Atmega328 like Uno, Nano or Pro Mini.
It will not be out of the box with Arduino Mega or other boards that are not 328 (or 168).
For the numbers of other controllers, at least the direct port operation section must be modified.
What I\'m going to mention here is that the system actually has a roof-like structure (
Below the anemometer, made in barrels)
The lid for the actuator part, but I don\'t have a photo of them.
This is the first summer element, I think, but in the long run it needs a cover and I just finished this part a little later.
Two failed attempts of \"damage control switch\" drill a power cord through the kill switch-
Therefore, if the system ignores the sensor switch, it will only disconnect the sensor switch and then click the kill switch.
Do not break the case or the motor holder or anything else.
The first version of the experiment is some aluminum sheet metal.
I bent a pair so that one pair hit the other, but it could be pushed away if the actuator block hit it.
These often fail.
I think it\'s usually because aluminum doesn\'t have much elasticity and they just push away from each other.
The surface can also be corroded a little.
My second experiment was to nail with clothes.
I drilled a few holes in their chin, crossed the wires and covered them with solder paste. Thisfailed too.
The surface is corroded, at least the part that has no indirect contact with the other surface.
I think most of the clothes are prone to tilt to one side, to slide the circular welded surface and then to the point of contact that has been corroded.
Next summer, I will buy some bulky switches that can do the job.
The bit needs about 3A constant current at work, and the peak value exceeds 10A at start-up, so it does not work for some small lever switches.
One day, I found that the rope was a mess around the screw bar.
I don\'t know how it happened.
But the condition of the car has stopped.
It is not the fuse that the electrical system fails.
Instead, the worst connection is the connection between the wire and a screw terminal.
The things inside got hot and pulled the screw terminal plastic open. somehow, the wire dropped. Clearly 1)
I need to test the lower fuse value and I am too generous for the 30 fuse.
But I think 10A is too low because I measured a similar drill tip when 10A started moving.
Its constant current is 3A.
So next year I will check what the 15A fuse will do. 2)
I have to make sure I have a good connection on the screw terminals
There may also be a problem.
Corrupting \"speaker wires\" the cheap black and red two core wires you see on most pictures are rubbish!
It is not made of copper, but some metal that is corroded outdoors.
I have seen them crash several times.
I did replace it recently with 2x1 Copper. 5mm (close to 16AWG)
Wires usually used for desk lamps, etc.
Similarly, the solar panels initially had the same crappy wires.
Also changed.
But I don\'t have a picture of the new wire.
The wear bars and nuts on the rebar and nut are longer than I expected --
Two days.
But their life is over.
I replaced them, but then the accident happened.
The problem came back a week later.
This time, I messed things up myself because I somehow didn\'t screw one of the mounting screws in correctly, and the wooden riding block got stuck when I hit the screw head.
This soon broke the thread.
So be careful to keep the track clear.
Getting stuck like this is not good for the battery either as it keeps trying and running out of the battery.
The pulley in the picture forms the shower wall.
They hold on for a while, but at some point a person starts to fall off their shaft.
Then I tried the bigger metal pulleys and made a stronger stand for them (
This time installed next to the actuator on the rod itself, not next to the plywood). Then . . .
I don\'t remember exactly what happened, but that version seems to be starting to be suspicious as well.
Anyway, I will revise the pulley section next summer.
I think it\'s important to add some guides and don\'t let the rope fall off even if it\'s a little slack or shake.
There are two features in the content code in the progressAs I mentioned in the code step that I haven\'t had a chance to test yet.
The battery voltage is recorded first, and if the impact limit switch is not detected within the preset time, the drill bit is turned off for the second time.
These should help better monitor and protect the battery if problems such as wear rods occur.
Future plans hope to make the measurements visible.
I think using the radio module and sending the data to another device in the room is the best solution.
I can then have it even post the data online or send the data to my vie GSM module.
But this may require the controller to be replaced.
So I will keep this project on github.
I will handle it if an error occurs.
If I make a version with a radio and a separate screen then it will be a separate repository.
Adding a watering system is also an option, but I don\'t have a definite plan yet.
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