Christina Holman | Design Blog

For the second class of "Principles of Engineering," my partner and I began where we left off last class -- just beginning the second lab. Consisting of two parts, Lab 1 focuses on ensuring the students attain a certain level of familiarity with the ArduinoUNO's coding language and applying the board in an electrical circuit. Specifically, the first part asks us to generate a code where three LEDs experience four sets of light patterns with the use of a single button. My partner and I started off well: we wrote out what we wanted the code to do; broke the procedure into steps (stages); and sketched a draft of how to structure these stages -- coding-wise. We wrote out the entire code to, at least, try something out. We uploaded the code -- and nothing. And, so, the troubleshooting began. Simplifying the code and removing the last two stages to test out the "switching" mechanism did not have an effect. Removing the second stage did not have an effect....

Welcome Back! After a few weeks of break, I am finally back at Wellesley College and ready to take on a new academic year and have just finished the first week of sophomore year. I'm looking forward to diving into Olin's Principles of Engineering, abbreviated to PoE,   (ENGR2210) and Wellesley's Mathematics for the Sciences  in addition to ECON102, ARTH259 and HIST205. What's more, I am helping manage the Wellesley Engineering Laboratory (We-Lab) while the department chair is on leave by organizing seminars, aiding set-up of events (e.g. Engineering Night) and implementing regular "open house" activities. I am now also the program coordinator for the Office of Sustainability's Bike Share Program and a peer tutor for the Physics Department (as well as an individual tutor for ECON101.) Feel free to see me in the Help Room on Thursdays! Since working under Prof. Battat this summer in creating a multiplexed digitizer for dark matter detection, the project...

It's Wednesday, July 30th and that means I have less than 6 hours to fully prepare for my poster presentation tomorrow (and pack). This entire week I have fluctuated between PCB layout design in gEDA software and finalizing the internship, though I have made the personal decision to continue my involvement beyond this summer. This entire week has been very active and I barely have time to come up for air. Over the last few days, I have submitted several renditions of the PCB layout, resolving issues such as incorrect traces, lost files, placing components on a dual-sided PCB and more. Most Physics and EE students -- including my advisor -- do/did not design a PCB until graduate school. And, here I am, as a rising sophomore, creating my own PCB. As I mentioned before, this internship has given me more skills than I could possibly imagine. Updates: MUXs are placed on the back-side of the board and connected to the top components with "vias" Two distinct ground planes...

We're finally making headway on this project! We are very close to finishing the PCB (thanks to a few extra weekend work days) and could most likely finish the PCB layout tomorrow. After passing around several versions of pieces of the PCB board, using the gschem software, Dr. Phillips, Prof. Battat and I have redrawn electrical connections, replaced components with others, implemented PCB footprints in all the components, checked for back termination and proper voltage levels, and, overall, used the "divide and conquer" method. I started with a tutorial on gEDA schematic drawings, and, now, I am drawing complicated, detailed schematics on my own. Most first-year Engineering majors wouldn't have half as much exposure to such professional techniques as Dr. Phillips and Prof. Battat have allowed me. They're absolutely challenging me, but I wouldn't take back one minute of this experience. Over the last two days, I've received constant feedback from my ad...

People who know me have heard me constantly credit a high-school STEM program for my "Aha!' moment with electrical engineering and, yesterday, the program held its final presentations ceremony (and alum reunion) for its 39th year in a row. As a rising senior during MIT's Minority Introduction to Engineering and Science (MITES) ten-week summer program, I came in with my mind set on becoming a chemist but was placed in the Electronics design course (my second to last choice). I started the first day of class trying to calm my nerves: "Oh well. I'll make the best out of it." Before I knew it, I had run to call my parents, telling them "I know what I want to do with my life! I want to be an electrical engineer." And my course hasn't changed since. I really have to credit MIT Professor Joe Steinmeyer for developing my love for electronics and encouraging it (e.g. he photocopied his entire Getting Started in Electronics  by Forrest Mims for me)...

Thursday, Dr. Phillips, Prof. Battat and I met from 10am to 3pm to focus on the design for the printed circuit board (PCB) to be used with the final prototype. We didn't even look at the gEDA software but, rather, discussed the needed components and their layout on the board itself. Once we found a room with a sufficient amount of white boards, the team dived into drawings and note-taking. Over the past few days, in debugging the breadboard circuitry, we have discussed greatly about the impact of impedance and capacity with long wires. We tried to eliminate such unnecessary distances with grouping families together, i.e. all the MUXes in parallel rows. We also looked into the issue of single-point grounding between digital and analog electronics. On the breadboard, the addition of a MUX to the same voltage supply greatly affected the abilities of the counter and could distort the counting completely. Additionally, we discovered that the MUX and 4-bit counter had ...

With all the progress made last week with the counter, we still are having trouble seeing the correct Vout signal pattern of the MUX. Prof. Battat returned today and looked at the setup himself, and we made a few changes. Today was filled with lots of bumps and hills, and, at one point, we even thought we had burned out the counter and solder another just in case. In the book Moonwalking with Einstein , Foer states that humans sometimes reach a "plateau" where their progress or betterment at a task no longer increases. Nonetheless, he finishes by writing that one can overcome this stage by being extra-meticulous in their search for error. With 3 weeks left, it is time to be extra diligent in our work. The first change was to remove the 50 Ohm surface-mount, resistors on the MUX because it was affecting the counter's ability to count. Dr. Phillips and I were unsure how to address the issue earlier, but he suggested the use of buffers. The binary counter can drive 50 mA...