Details of electrical connections for the grow light and water pump
The relays that switch the light and the water pump were enclosed inside a junction box so there are no exposed wires and terminals for this part of the circuit.
The control cables came through the bottom of the box, just next to the Edison Board. The relay block has 4 relays but at this stage, I am using only 2.
The other 2 I will have as spare as I have plans to install an air blower to force air into the drum if it gets too hot or too humid and an air pump to aerate the nutrient.
Edison/Arduino Board & LCD Display
The Edison board was fixed next to the relay "junction" box. The display was mounted in a piece of timber and fixed on the top frame facing the front of the machine. The PH sensor board was mounted on the back of the same mounting.
Temperature/Humidity & Light Sensors
The sensors to monitor the drum temperature, humidity and light intensity were fixed on the light mounting. This is the only spot I could find that will not be on the way of the moving plants or blocking the light.
It was mounted in the frame next to the stepper motor.
The PH probe was fixed in the dump pipe with a metal clip secured by a cable tie.