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2015 March 18

Freshman design projects moderately successful

I just finished grading this year’s freshman design projects. I think that the projects were more successful this year than last year, in part because I kept the students focussed on electronics and programming (for which they had lab access and which I could help them debug), and in part because the projects were somewhat less ambitious.

There were two groups doing EKGs and 4 groups doing blood pressure meters.  Both EKG groups managed to demonstrate their projects working, as did one of the blood-pressure groups.  (I’m being fairly generous here about what “working” means—they had to get their electronics to work, capture the data, and plot the waveforms, but further interpretation or software was not required.)  The other three blood pressure groups did not manage to demonstrate their projects, but one of them managed to plot waveforms for the pressure measurements (without getting their high-pass filter and amplifier working for the pulse measurements).

Some things I learned for next year:

  • Tell the students what op amp to get.  A number of students picked op amps that turned out to be rather old-fashioned ones with very low input impedance (as low as 2MΩ), rather limited output ranges, and external nulling circuits. The cheap MCP6002 or MCP6004 chips would have worked better at lower cost.  In fact, I gave one group that seemed to have a good schematic (but couldn’t get their circuit to work) an MCP6002 chip, which they wired in place of the op amp they had been using, and their circuit worked immediately.  I would have done the same for other groups, but the others with poorly chosen op amps were about a week behind and did not have circuits that were that close to being functional.
  • Warn students sooner not to use FedEx.  My son’s and my experience with FedEx this year has been that they are ludicrously slow. At least one group was burned by a ridiculously long delivery time, having ordered with FedEx delivery just hours before I warned the class about them.  (The US Post Office is faster and cheaper for lightweight electronics orders from Digi-Key.)
  • Students who never ask questions in class probably don’t understand much that is going on—all the groups that successfully demonstrated their projects had at least one active participant in class.
  • Students who fail to turn in their progress report are almost certainly not going to complete the project on time—I need to be more assertive in getting them moving and demanding that they show me their schematics.  Almost everyone had errors in their schematics on their first design (and one of the successful groups went through 4 incorrect designs before getting to one that worked).  Students that are afraid to show me incorrect or incomplete work don’t get the feedback they need to correct the problems—I need to normalize errors more and insist on seeing stuff, even if it is wrong.
  • The MXP5050DP pressure sensors are very easy for students to use, though a bit pricey at $16 each.  The built-in amplifier makes doing pressure measurements with an Arduino fairly trivial (hook up the three wires of the sensor to A0, +5V, and GND).  They were a good choice for the freshman design seminar, though I’ll continue to use MPX2053DP sensors without an integrated amplifier for the applied circuits class—that assignment is intended to get students to design with an instrumentation amp and to understand a bit about strain gauges.
  • Get the students to plot stuff earlier in the quarter. One group tried installing gnuplot on a Mac in the lab in the last few hours, which did not go well for them.  They did eventually find a plotting program that they could install and run, but then did not have time to run the data they collected through the filtering program I’d written for the class.  Their signals were pretty clean, though, and the plots they produced were good even with just the RC high-pass filter in their amplifier, without digital filtering.
  • The students seemed (for the most part) pretty excited about the projects—even those whose projects didn’t quite work seem to have gotten a lot out of the lab times.  I should look in a couple of years to see how many have stuck with engineering majors (I suspect that some might switch to computer science or computer engineering, rather than sticking with bioengineering, but that’s ok).

2015 March 14

Not been blogging much

Those who have been following my blog for a while may have noticed that my blogging frequency has dropped quite a bit for the past few months.  I had planned to blog after every class meeting of the freshman design seminar, as I did last year, but I’ve simply been too busy. In addition to teach the freshman design seminar, I was also teaching the senior thesis writing course. Although both of these are 2-unit courses with small numbers of students (so the department gets essentially no additional resources as a result of my teaching them), they are both somewhat time-consuming, though the senior thesis writing much more so than the freshman design.

This weekend is the first weekend that I did not have a stack of thesis drafts to provide detailed feedback on (I’ve been averaging over 6 drafts a week to comment on all quarter).  In addition to the thesis drafts, I also arranged to have a 20-minute individual meeting weekly with each of the 19 seniors writing theses this year.  Because the meetings often ran over, I spent about 7 hours a week on those meetings.  I started each meeting with the student giving me a 2-minute elevator talk (after telling me what audience they were addressing the talk to and with what purpose). This served two purposes: to get the students to practice concise descriptions of their projects and to remind me which of the 19 projects we were talking about. (Several pairs of students were doing closely related projects in the same lab, so it was really easy for me to mix up the projects—and I have almost no memory for faces and names, so I needed the prompts!)

Next weekend I’ll pay for this weekend off—I’ll have all 19 theses to grade between Thursday night and Tuesday morning.  I won’t be doing as detailed feedback on this round—first, because there aren’t enough hours to do 2–3 hours a thesis; second, because I suspect that half the students won’t come by my office to pick up the graded theses (even those who still have a quarter to go before their theses are complete).

I hope to have the freshman design course all graded before the senior theses come in—they have their last lab on Monday and their design reports are due Tuesday.  The freshman reports are much shorter than the senior theses, so I can probably get them all graded on Wednesday.  If I get them done in a timely manner, I may take the time to try to do an end-of-quarter summary of the freshman design project course, which I think ran more smoothly this year, though not quite in the direction I had originally thought we would go.

This weekend, I’m getting back to work on my book, since I want to release a draft for the applied electronics course that starts in 2 weeks. I at least want the chapters and labs for the first two weeks to be finished, with no major overhauls planned for the remainder. I spent about 4 hours on the book today (after goofing around for a while with some phototransistor circuits that aren’t really relevant to the course—I’ll probably blog about that when I have more time, but it will take about 8 hours to do a good blog post on it, and I don’t have that much spare time this week). I hope to have the schedule for all the labs finished this weekend also—I made a good start on that in December, when I last had time to work on the book.

Next quarter will not give me much writing or blogging time—instead of the 12 contact hours (plus office hours and grading) that I had this quarter, I have 19 contact hours (3.5 hours of electronics lecture, 12 hours of electronics lab, 3.5 hours of banana slug genomics) plus grading 15 prelab assignments and 15 design reports a week for the electronics course. I’m hoping I can convince my co-instructor to do what grading we’ll need for the banana slug genomics, or that we won’t assign much that needs grading.

Also Spring quarter is when most students declare their majors, so I’ll probably have to increase my office hours from 2 hours a week to 3 or 4 to handle the advising load.  Two hours a week was just about right this quarter, especially since I allowed students to reserve a place in line by email.  I only had an empty office once or twice, and only ran an hour over once or twice.

On the administrative side, at least I’ve gotten the 20-page bioengineering self-study  and my 3-page contribution to the bioinformatics self-study done, so I won’t have too much to do on those next quarter.  The Curriculum Leave Plan is done for next year, and I hope it won’t need further modification. I’m reducing my teaching load next year to merely heavy (from insane this year), and some of the buyouts we had counted on for paying lecturers are not coming through, so the department has a structural deficit of about $30k, and only enough reserves to cover that for a couple of years (with no way to replenish the reserves).  I don’t know what we’re going to do long term, as we need to add more offerings of some of our more popular courses, at a cost of about $20k each.

2015 January 19

More on freshman design projects

Filed under: freshman design seminar — gasstationwithoutpumps @ 22:01
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In Student project ideas for freshman design seminar, I listed some of the ideas students had brought up as possibilities for the freshman design seminar. For homework, I had them each comment on at least two other projects on the class e-mail list. Today, I counted commenters on the various proposed projects for the freshman design seminar:

5       temperature sensor (IR? I may have been lumping a couple of different temperature sensor ideas together—I did not follow all the links.)
4       PCR machine
4       blood pressure monitor
3       photogate
3       pH meter
2       colorimeter
2       EKG
2       fume extractor
2       sound level meter
2       centrifuge
1       microbial fuel cell
1       photospectrometer
1       general sensor
1       pulse monitor
1       function generator
1       lensless microscope
1       voltmeter
1       LED color mixer
1       motion sensor
1       stir station

I notice that no one picked the bacterial incubator project this year, which is too bad, as I have a dozen styrofoam shipping boxes that would be ideal for the project, and I spent a fair amount of time figuring out how to do the control loops (Temperature-control project for freshman design seminar, PWM for incubator, More on incubator design, Thermal models for power resistors, Thermal models for power resistor with heatsink, PWM heater and fan, PWM heater and fan continued, Controlling the heater and fan, Putting the heater in a box, Improving feedback for fan , Thermal control loop working (sort of)) and how to teach them.  Of course, given how much time it has been taking to teach reading a simple photodiode, I don’t know that I’d actually have been able to get through teaching proportional-integral control with anti-windup provisions, so maybe it’s just as well.

We’ll discuss possible projects on Wednesday.  I think that I can cross out a few as being unsuitable for the lab facilities we have available (no sinks, so wet-lab stuff is not reasonable) or as pointless, and one or two as too ambitious, but most of the projects are reasonable.  They vary a lot in difficulty, though, so I’ll have to help the students match their ambition with their willingness to work.

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