Today, I was with the digital group who is one of two groups of electrical engineers at Plexus. I finished up some CAD in the morning for the box for everything to sit into. I realized that I needed screws that would go into the sides of the box, but my sides were probably too thin for standard screws to go into and I forgot some important holes in the side of the box. These ended up sounding kind of basic written down but they didn’t present so easy on CAD. Kyle showed me how they use CAD for laying out circuits for boards. It was also interesting to learn about the various ways things can be soldered with both wave and with paste. After a really fun lunch, I visited the lab in which I was introduced the wide variety of lab equipment that they have at Plexus. I was shown how you can use an oscilloscope and all the different wave forms that you can see. We also talked about how box waves are formed using many different sin waves. There is another piece of equipment that graphs frequency over power which would show many spikes at many frequencies for a box wave. After spending some time doing calculations using a multimeter and information provided by the manufacturer, I was able to find the resistors needed. My biggest design challenge was that I needed to control a 12V pump off a 5V Arduino. I couldn’t power the pump through the Arduino for obvious reasons so therefore, I had to have a switch to control this, which created another problem. I didn’t want the user to have to flip a switch every time the plant needed to be watered. Therefore, I needed a Transistor. Transistors allow power to flow when the voltage proved to one of the pins is sufficiently high or low. This solved my problem. The one main electrical component that I still have out standing is the sensor for soil level. This should be fairly easy to install but will need to be tested for the values for high and low. I can’t believe that it is already day 4 and we are almost half way through. I have included some photos below of my notebook with some electrical diagrams and calculations about resistors below.
