I started this project two years ago to blend two of my favorite things, make technology and grow plants. Today I will show you a step by step guide of how to build an automated hydroponic led indoor.
To make the machine more comprehensible, we will see four sub-systems and call them:
- The Buddha subsystem. Is in charge of bringing light and so enabling the photosynthesis and others necessary process for the plants's physiology.
- The Aquarius subsystem. Is in charge of recirculating the hydroponic solution.
- The Prana subsystem. is in charge of renewing the air and maintaining the correct levels of CO2, humidity and why not temperature too.
- The Human Interface subsystem. is in charge of bringing the human interface to operate the machine, and also the M2M communication that enables to interact with the machine from anywhere in the world.
Knowing that, let's start with the first step.
Step 1: Choosing Where
You can choose the place you like the most. In my place I chose a vintage refrigerator for several reasons, perhaps the most important one was to recycle and give new functions to beautiful objects from the past. Remember that if you use natural resources such as sunlight, wind and rain water, your hydroponic machine will be more friendly to the environment.
Step 2: Making the Buddha Subsystem
In early stages of this project, I've been using mercury vapor and High pressure Sodium lamps. But after researching through magazines, internet and talking with my professors at the Faculty of Agronomy of the University of Buenos Aires, I started studying the properties of led lights and it's benefits, such as reducing power consumption, heat and size.
The choice of the correct wavelength depends on the plants and physiological process, but "normally" it's used a 4:1 relationship with wavelengths of 680:400 nm. Is that right? What do you think?
Having chosen the correct wavelength, proportion & irradiance needed, the next step is building the electric schema for the Leds, or buying one led array panel according your needs.
For this case, I chose to build it on my own with high power leds of 3W, and PC’s power supply.
Step 3: Making Prana Subsystem
The plants are autotrophic organisms capable of absorbing light energy in order to transform CO2 into Carbon chains. Thanks to that property the plants sustain life in the planet, that process is called photosynthesis.
Besides the provided light from Buddha's subsystem, our plants will need CO2. For that reason and to maintain accurate levels of Humidity and temperature, Prana recirculates the air between the inside and outside of the chamber.
Maybe this subsystem is simpler than the others, but it was not easy to make. In order to cut the hard metal of the refrigerator I needed a circular saw, a saw, 2 pair of safety glasses and a helper.
In order to choose the holes size, it's necessary to know first, the fan size, one to extract and other to inject the air from the outside. In case you want to lower your design budget, experience has proven me that in a close space you can use only one fan to extract air and air will enter passively with no need of a second fan.
Once the holes were made, it was necessary to seal them. The best I could find for this was a metal tube and putty.
Step 4: Making Aquarius Subsystem
If you browse through the internet you'll see a variety of hydroponic systems, the correct choice depends on the plants you want to grow, the place you have and equipment you can get. Here, I choose a floating roots system with recirculation. It's composed with:
- Two 18 litres tray where the plants will grow
- One 72 Litres water tank
- A water pump, hoses & gravity to make water recirculation.
- A fish tank aerator to oxygenate the hydroponic solution
When automating a system autonomy is really important. Today, the machine I built needs a human in order to fill the water tank and make the hydroponic solution, therefore the 72 litres of the water tank are a fundamental piece of the Aquarius subsystem that helps to store more hydroponic solution, and so providing more autonomy in which some cases can last up to 2 weeks without any human intervention.
Your nerdy side is maybe thinking that it would be great to provide more autonomy to this machine, but you must remember that seeing a plant growing is something that gives pleasure and if you are lucky you might be see them as your pets. The Autonomy of this machine is there so you can go on vacation knowing that everything will be ok when you return.
This subsystem also required a hole as the ones described for Prana Subsystem. But this time it was meant for passing the hoses between the tank and trays.
Step 5: Making Human Interface Subsystem V1
This subsystem is in charge of:
- Controlling all the subsystems
- Monitoring variables of interest
- Connecting to internet
- Bringing the humane local interface
In a first version I used the following a "star type" architecture, a bit scalable and centralized in the Arduino, but “easy” to develop using internet example, for which if you are a beginner it's a high recommended solution.
For this version I used the following components:
- Arduino Mega 2560
- GPRS shield
- Display Led 128x64
- Keyboard 4x4 keys
- DHT11, LDR
- Some relees y triacs
As in the other subsystems where there's not just one option, in this one you can choose between different architectures and microcontrollers. Such as, Arduino, Raspberry Pi, Freescale, NPX or any other from within the infinity of development boards that currently exist.
Step 6: Making Scalable Human Interface Subsystem
Although if you have a little experience in embedded systems, the recommended solution is the following one:
In this scheme we can see how the modem connect the machine to internet using cell phones network, and through Zigbee can communicate to some devices to control and sensing.
This is the list of components that I used for the newer version of Human Interface Subsystem:
- An ARM Cortex M0+ microcontroller
- HC05 for Bluetooth interface.
- GPRS Shield
- Two XBee
- Two ACDC converter
- Six triacs
The components interconnection can be seen in the scheme.
On the other side of the cloud are a Linux server for serving the requests and responding to the modem. On the same server the web application and the data base that registers each action performed in the system.
I haven't developed the sensor module yet, I'll be working on that soon, you could follow the scheme architecture to add sensor to this hydroponic machine.
Step 7: Growing Plants
Now all are ready for the most important thing, which is seeing the plants grow, and some day harvest for eat.
Please remember to use all the natural resources that you can get.
Recycle is good! If you want to see more pictures visit this link.
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Have a happy farming!