- Parm and Le stripped the neutral wire on the plug-side of the cord, then soldered the two neutral wires (from the plug-side and pump-side) together. This connection was insulated with electrical tape.
- The hot wires on the plug-side and pump-side of the power cord were connected via alligator clips to the common pin and normally open pin on the relay, respectively. These connections were well-insulated with electrical tape as well, to remove the possibility of a short-circuit occurring.
- Two jumper wires were connected to the two coil pins on the relay (again via alligator clips, with all connections insulted by electrical tape), then inserted into the breadboard, where other jumper wires completed the connections from the relay to the ground and power output on the Arduino. These jumper wires can be seen connected to the alligator clips in Figure 1, and Figure 2 outlines all connections to the relay.
|Figure 1. Jumper wires in alligator clips. The other ends of the alligator clips are connected to the coil pins on the relay.|
|Figure 2. Schematic of relay circuit.|
- Davina wrote a simple testing code for the Arduino, which turned the power output pin on and off every two seconds. This corresponded to the relay switching on and off every two seconds.
- Michelle filled the water container halfway with water and firmly inserted a small piece of plastic tubing into the output hole on the pump, readying it for testing.
- The whole apparatus was brought down to the electrical materials department for a last expert check of the wiring before it was plugged in and tested. The apparatus (without water) can be seen in Figure 3.
|Figure 3. First working prototype of PlantParent, with all components connected successfully.|
The results of the testing were extremely promising. When everything was connected, and the apparatus was plugged in, the pump turned on and off every two seconds, as expected.
There appears to be a minor error in the wiring, so that the circuit is normally closed rather than normally open when plugged in. This just means that the pump is on by default, and the activation of the relay turns it off, rather than the other way around. The team could either change the wiring, or, since it is exactly backwards in function, they could simply reverse the programming logic instead, which is the plan going forward from here.