You will be placed in groups of 4-5 students to build a project which combines the various components we have discussed: diodes, transistors, flip-flops, hall sensors, relays, switches, and the Arduino. A drawing of the project board is shown below.
Figure 7.1: A diagram of the design project setup. The ends of the loop will be provided.
Two teams will share space on each project board.
Each team has 44” of space to work with. At the beginning and end of this length, you must have a straight piece of track which is at least 2” long. What you do in the remaining 40” is up to you. The width of your project is not strictly constrained,
but it must not interfere with the work of the team across from you.
For project ideas, look at the project videos on http://www.princeton.edu/
~mae412/. These projects are far more complex that what we expect you to do, since you will only have two weeks. However, you might be able to derive some ideas from previous projects.
Part of the engineering process is proper planning. Therefore, before you start building your circuits and putting together train tracks, you need to submit a project proposal. The proposal must include a drawing of your proposed project (either made on the computer, or hand-drawn very neatly). You must label all relevant dimensions of the track and include all components which will be on the board (hall sensors, motors, etc.). Your drawing should be detailed enough that two groups working independently off the same drawing would make the same project.
You also need to include a parts list, which includes the following:
• Switches (teams are limited to a maximum of two switches)
• Relays
• Flip-Flops
• Hall Sensors
• Track pieces
• Any other special parts you need (please talk to me so that we can see if it is feasible in terms of budget)
You must specify how many of each of these you will need. Track parts are only available in certain dimensions. You can find the possible track parts here:
http://www.atlasrr.com/Trackmisc/ncode80.htm. Note that we will not be using flex-track. You need not specify parts such as rail joiners, nails, and wire in your parts list.
In addition, you should write a short description of how the project will work.
What is the exact sequence of events that will take place? Keep in mind that since
the track is shaped in a loop, the train will come back onto your project over and over again. This means you could design a project that alternates between two things each time the train enters your project. The more you think through the details now, the less likely it is that you will have trouble later.
Finally, a note on grading. The most important factor in your grade will be robustness: does your project consistently do what you say it will do? Other fac-tors will include complexity and workmanship. Individual contribution will also be considered.
If you have any questions, email me at [email protected].
Conclusions
Though I haven’t yet finished teaching the mini-course, the results so far have been very positive, and I am glad that I took a risk and pursued an unusual thesis.
One of my primary objectives when I started this thesis was to expose high school students to the fun and interesting applications of physics and engineering, and based on the feedback I’ve received from students, I’ve been successful in accomplishing this objective. When I informally surveyed students during class to ask them what they think about the work I am asking them to do, I received comments like, “It’s challenging, but it’s also fun” and “It’s nice to actually make a circuit that does something.” Teaching high school students has also been very fulfilling for me; I’ve always enjoyed mentoring and this project gave me a chance to teach a subject I am passionate about while simultaneously giving back to my alma mater.
The work I accomplished also aligned quite well with the objectives I proposed at the beginning of this year. I had written that “the course will consist of eight classes, as well a week-long design project.” In the end, I developed only six classes, but made the design project more extensive, so that it would take two weeks rather than one.
While I view my thesis as a success on the whole, there are a few things I would do differently if I were to repeat the project. First of all, I would allow more time to teach each lesson. I overestimated the speed with which the students would be able to build the circuits. I quickly learned on the first day of teaching that many students didn’t know how to read a circuit schematic or had never used a breadboard before. This lack of familiarity meant that building circuits took more time than I
had expected, and it was often difficult for students to complete the lab exercises in the twenty-five minutes I had allotted. As a result, I modified my lessons as I went along, shortening the lecture component as much as possible to allow more time for building the circuits. Especially for the last two lessons, where the lab exercises are quite extensive, I limited my lecture to a discussion of the circuit itself, while omitting all extraneous information. I would recommend that for future years, each lesson be split into two, so that forty-five minutes can be dedicated to an in-depth discussion of the theory behind each circuit, and a full forty-five minutes can be given to complete each lab. This would help ensure that most of the groups in the class finish the circuit, rather than only the fastest groups.
I would also recommend that all the lessons be taught consecutively. I taught lessons once a week (typically the Friday of every week). In one sense, this was a nice break from the regular classwork that the students had, and I got the sense that the students looked forward to doing something different but still intellectually challenging at the end of the week. However, the downside of teaching only once a week was the lack of continuity. Transistors were introduced in the first lab but not used again until the fourth lab, and many students forgot how transistors worked in the intervening three weeks. Had the lessons been taught consecutively, this gap would have been much shorter. I’ve discussed this suggestion with Mr. Higgins and he agreed that it would make sense to structure the lessons this way in future years.
There is usually about a month of school between the end of AP exams and the end of the school year, and this would be the perfect length of time to each the lessons and complete the design project.
There are many directions that future work could take. One direction would be to dig deeper into the physics behind each component. For example, when discussing how relays work, I simply stated that a current-bearing solenoid induces a magnetic field in the iron armature, but I didn’t go into too much depth as to the reason behind this. It would have been possible to discuss the quantum mechanical interactions that lead to magnetic domains. I didn’t go into this topic because I was restricted for time, but with more time, topics like this could be introduced.
Another direction for future work would be to introduce more components. In
MAE412, we spent the first half of the semester building our own computers, by putting together a CPU, RAM, EPROM, VIA, etc. Again, because of the time constraints, I used an Arduino instead. While the Arduino has the advantage of being easy to use, building a computer from scratch would have led to a much better understanding of how computers work.
Finally, a completely different direction for future work would be to build lab kits for high school physics classes and commercialize them. Most high school science departments don’t have the time to develop extensive projects like this, but it’s possible that they might be able to purchase ready-made kits. Of course, to determine the viability of this idea, it would be necessary to perform significant market research and determine if there is enough demand for a product like this, and if the price point would be accessible to public school districts. If it was financially feasible, it could be a great way to get more hands-on learning into the physics classroom.
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