Christina Holman | Design Blog

The printed circuit board design is a projection of the schematic design. The placement of the footprints for the set of jumpers was positioned intentionally to allow for the power lines to be connected simultaneously as well as for easy access when soldering. We went through several iterations in design due to mishaps in communication -- a key issue in engineering firms. It took me a little while to understand just exactly how Battat envisioned this project and the best way to design such. At first, different components were in place than in the final design: I moved from three-way jumpers that resembled the slapstick original design for the Electronics Lab (without direct input into the rails); to long rectangular flow mirroring the circuit schematic; and to a dual-pin jumper and stacked 805 footprints. Finally, I ended with a reasonable and compact design for the PCB power supply. OSH Park, a community printed circuit board order, charges $5 per square inch of a dual-layer bo

For Fall 2014, I decided to continue my work under Professor James Battat with the dark matter detector and he suggested doing so under PHYS250H -- an independent study in the Physics Department -- in order to receive credit for it. However, the project portion of the course veered from work with the PCB I created earlier and towards design of a PCB power supply for his Spring class PHYS310 "Experimental Physics." The power supply was needed for an Electronics student lab,  where a five-pin DIN draws in four voltage levels of +12V, -12V, +5V and GND for a solderless breadboard. The PCB I designed would use this connector to draw in the four voltage levels, filter for overcurrent and allow direct input into the rails of a solderless breadboard. At the beginning of the process, Battat and I create a concept diagram demonstrating the overall flow of the power supply and, from it, a rough circuit diagram was generated. Over time, the schematic changed with additional and

Demo Day was a huge success!  The night before, Griffin and I were able to see the final product and discuss what to work on/test for a brief moment, and I was able to get there before the scheduled presentation to clean up a previous team's remnants and prep our own product. Griffin and I were able to test a spiral design on a few sheets of paper on top of our dummy cake -- and it looked beautiful as onlookers watched and Griffin videotaped a portion. Unfortunately, we were unable to setup the limit switches properly as I would have liked to do so. Though, the positioning system of our polar-coordinate-based rotating platform worked so well that it did not matter as much as I was worried it would. Cassie and Emily then walked in with our final, pre-frosted chocolate cake for the demonstration. While they went on to watch others demonstration, I decided to create and edit a short promo/trailer video of our Cakebot to add into the presentation that would happen in 15 minutes.

Demo Day is Thursday, December 18 -- but our project website  was due  Monday, December 15. Having met several times over the last week and half, my team has been pushing to finally finish our full mechanism. Griffin and I were lucky to have the electronics systems finished, except for the limiting switches, a few days ago. I tested the motors and Arduino code to ensure that we were able to move them appropriately, and Griffin worked diligently to wrap up the GUI as I tried to offer what little python I remembered. However, in the midst of finals week at both Olin and Wellesley, the mechanical aspects fell a  little behind as my teammates were fighting for space in the woodshop and laser cutter with the many other Olin students who needed it for their own projects. With the majority of my project finished, I took charge over the website as the only individual familiar with Weebly hosting-site. Originally, Griffin setup an HTML template for us all to edit but, as it began to prove

After the DRII, we took our compliments and criticism to heart and set off to finish what we said we would do before the final Demo Day. Griffin and I looked into the malfunctioning rotating platform and realized the issue was more mechanical than anything electrical or software: Cassie and Emily made note to handle the issue in our final prototype. Griffin and I worked heavily on integrating the pyserial code with the Arduino system: he came up with the genius idea of having the pyserial/GUI send three-letter codes that correspond with motor actions, i.e. calibration of the platform stepper, forward movement of the top stepper, extruding of the top DC, extruding of the side DC motor. We were able to record all our changes of the final sprint code using  GitHub  -- a cloud management system for sharing and collaborating on code. Griffin introduced me to the system and I plan on using it much more often now that I understand its magic. Furthermore, in testing all the motors, I was a