I found a schematic for a Ph meter that I'm likely going to use with this project. I'll be ordering the necessary parts for that on Friday, along with a few peristaltic pumps for dispensing nutrients. My plan is to start sketching up the initial prototype with FreeCad (a 3D parametric CAD program). I remember some work that was done by NASA with regard to utilizing high voltage as a means to enhance plant growth, so for at least one of the growing tracts, I plan on having an adjustable high voltage mesh that sits directly above the plants. The high voltage will be generated by a simple cascade/ladder circuit using diodes and capacitors (ideally from the build kit). I have a small keypad that I can utilize for direct user input into the system, but my current plan is to utilize one of the boards from the kit as the means to run the backend API. I'll get my domain name registered and basic hosting set up later this week, along with the initial version of the database schema.
My current design will be predicated on purchasing low cost, readily available parts from the local hardware store (Home Depot/Lowes). To my knowledge, we haven't been given the specifics on what types of plants we are growing. To that end, I'll be designing a heat exchanger system that utilizes a Peltier device to put the nutrient bath at a constant temperature that is ideal for the plant root system. A larger "mini-hvac" system will need to be developed as well to keep the grow chamber at optimal temperature and humidity as well.
In order to minimize the system's water utilization footprint, I will be developing a small solar still that will accept as input the expended nutrient bath, and will have as output, distilled water that can subsequently be used by the system. I'm planning on having the grow chamber be covered with reflective mylar film so that plants absorb as much ambient sunlight and room light as possible, while also capturing water that is transpired from the plants as they grow.
I'm looking into a couple of different options for misting systems so that the humidity can be controlled appropriately, and the plant leaves can be misted if desired. All facets of the operations of this system will be controlled by the microcontroller, and data will be logged to the website in real-time.
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