Nutrient film technique (NFT) is an efficient low-maintenance hydroponic system. The usual maintenances are: pH adjustments, refilling the water reservoir, and adding nutrients. These tasks are easily automatable if the NF site has decent infrastructure (i.e. water and electricity).
The aim of this project is to create fully automatic NF system. With this system, you can leave your plants unattended for weeks or months and still profit from the excellent harvest of the NFT.
All sensor data will be available in real-time through a web-interface. The interface will also allow changing the target pH, changing the nutrient levels, and completely flushing and refilling the water reservoir. Furthermore, a web-cam will be installed to pick a perfect time to gather harvest.
First prototype of this project will be done on a bubbler hydroponic system by the end of 2014. The whole system will be built and in beta-testing for the summer of 2015.
Connectivity schematics for the electronics (with device codes from the process schematic) below. "UDOO" is a tiny PC with embedded arduino due, although I'll be using a separate due board. "Volt. div." is a voltage divider circuit for matching the sensor output to the ADC voltage limits, and "Instr. amp." is an instrumentation amplifier. "Q1"--"Q9" refer to switches, most likely power MOSFETs. Dashed line shows the individual boards; I'll place the pressure sensors (i.e. water level sensors) on the board in order to have the amplification as close to the sensors as possible. I'll make the final schematic with eagle once I've chosen the components. Next-up: Software