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2015 November 25

Buy Nothing Day

Filed under: Uncategorized — gasstationwithoutpumps @ 20:00
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Today I got a message from Leanpub, the site where I’m selling drafts of my Applied Electronics for Bioengineers book, suggesting that authors provide a discount for Black Friday, the biggest shopping day of the year in the USA (or one of the 10 biggest, depending whose figures you believe).

My family doesn’t engage in the demented frenzy of orgiastic consumerism that the day after Thanksgiving has become in the US.  We, instead, stay home and celebrate Buy Nothing Day.  The celebration is simple: we stay home and buy nothing that day—not venturing out into the crazy traffic of drivers too stoked on the thought of bargains to look out for pedestrians, not doing on-line ordering, not even ordering pizza by phone (though we did do that one year, when we didn’t have enough food in the house for dinner).

Despite our family’s habits, though, I’m going along with Leanpub and offering a discount on my book:  From Friday 2015 Nov 27, through Monday Nov 30 (“Cyber Monday”), I’m lowering the minimum price on my book from $3 to $2.50.  As always, this includes not just the PDF of the current book, but all future updates for as long as I’m publishing the book with Leanpub.

Quite frankly, I doubt that the 50¢ difference (17% OFF!) will result in any more sales. Most of the purchasers of the book are paying more than the minimum anyway (average currently is $4.89, and that includes several people whom I gave free coupons to).

2015 November 23

Meeting for teachers of writing to engineers

Filed under: Circuits course — gasstationwithoutpumps @ 19:00
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Last Spring I got a small grant from the Academic Senate to create a new “Disciplinary Communications” course for the bioengineering majors (a $7,000 “partial course relief” for 2015–16).  Most of the effort of creating the course happened last year, as we needed to offer the course in Spring 2015, but the money comes for this year.  I’m not actually taking any course relief this year, though my load is lighter than last year, since I’m not doing two overload courses this year.  The money (as all our course relief money) is being spent on hiring a lecturer—paying part of the salary of the lecturer teaching the new writing course.

But I felt that I ought to be doing something this year on improving “disciplinary communications” for bioengineers, in order to have something to report at the end of the year for the grant.  Since the new course was designed last year, the main effort this year will be on tweaking that course and other courses our students do that involve writing.  Rather than work just with the instructor of that new course, I thought it would be useful to gather all the faculty who teach writing to engineering students, to discuss (according to the message I sent out):

  • course design
  • teaching techniques
  • assignments
  • grading techniques
  • use of TAs or graders
  • creation of a “Professional Learning Community” to meet on a regular (quarterly?) basis

There was no set agenda for the meeting—just a chance to meet and talk about what we do. We had a pretty good turnout: 3 ladder-rank faculty, 4 writing instructors, and 1 staff person who teaches writing to a small group of minority students.

After self-introductions we had a wide-ranging conversation about assignments people gave, challenges they faced, approaches to making assignments work better, and so forth.  We did not talk much about TAs and graders, course design, or grading techniques, concentrating more on assignments and teaching techniques.

I’m a lousy note-taker, so I don’t have good notes of what was discussed, but I remember a few things.  I’ll present them here mainly as they apply to me, since that is what I remember best.

None of the ladder-rank faculty are teaching courses where writing is the primary content of the course, but improving student writing is a secondary goal of their courses. In my case, I’m (thankfully) not teaching either the technical writing for bioengineers course nor the senior thesis writing course this year, but I do provide a fair amount of writing feedback both in the Bioinformatics: Models and Algorithms course and in the Applied Electronics course. In the bioinformatics course, there are a couple of writing assignments, but most of the feedback is on in-program documentation. In the Applied Electronics course, there is a weekly design report due, which is centered on the graphics (block diagrams, schematics, and fits of models to measured data). Other courses include assignments to write abstracts, write proposals, write standard operating procedures, and other assignments typical of both academic and industrial writing tasks.

One aspect of teaching writing that I’ve never had much luck with is peer editing—another of the ladder-rank faculty brought this topic up as one of the challenges that help was needed on.  A couple of the writing instructors agreed that peer editing was hard, because the students had no notion of “editing” as an activity. What they suggested was having a set of specific questions for the peer editors to answer—questions relevant to the piece they were editing, like “what is the research question? Is there a summary of results? Is the approach clear?” for editing an abstract.  Without specific guidance, students tend to fall back on the if-you-can’t-say-anything-nice-don’t-say-anything meme, and provide useless “looks good to me” comments.  One technique that the faculty member who raised the issue has tried (with mixed success) is getting students to rewrite another student’s abstract in their own words.  Although this often pointed out problems in the original writing, it sometimes just reflected the inability of the editing student to write coherently.

One idea that seemed to come as a bit of surprise to some of  the writing instructors was creating the figures and figure captions of a document first, and then writing the paper around the figures.  This is a common approach in some research groups in our department, and one that some students will have to face. One of the writing instructors pointed out that the poster assignment (used in two of the courses) is good preparation for this.

We all pretty much agreed that there was no place in the writing instruction students were getting about good presentation of data and generation of figures. I mentioned that one of our junior faculty is interested in creating a course centered on scientific graphics, but it wasn’t clear whether he’d get to teach it next year or not.  I felt that students in my Applied Electronics course got a lot of instruction and got pretty good at displaying data (at least the scatter diagrams and fit models for that course), but that they really struggled with the notion of block diagrams and organizing problems into subproblems. One of the writing instructors, who saw the students mostly after they had had the applied electronics course, saw more problems with data presentation than with block diagrams.  This may be because of different expectations of the block diagram, or it may be that the data representations her students needed were not among the few types covered in Applied Electronics.

Another form of writing that a lot of students were not getting adequate feedback in was lab notebooks. Unfortunately, the different disciplines have such different expectations of the content of a lab notebook that it is hard to provide any sort of standardized assignment. A couple of the instructors who teach Writing 2 classes, mainly to STEM students, do include an observational-field-notebook assignment, which at least gets across the idea of taking notes as you go, and not trying to reconstruct what you did at the end of the day (a flaw I’ve seen in several of the Applied Electronics labs) or the end of the quarter (a flaw I’ve seen in some senior theses).

We did discuss the strategy of setting high expectations on the first assignment by giving detailed feedback on that assignment, with reduced checking on subsequent assignments.  This helps keep the grading down to an almost sane level, and the students still benefit from the practice, even if not everything they do is checked. I’ve certainly noticed on the bioinformatics assignments that by the 4th or 5th assignment I only need to spot-check the internal documentation, or check it for students who are struggling with the concepts of the assignment, as the better students generally are routinely producing decent documentation by then.

We discussed various things we could do that would be generally helpful, and I ended up with two action items:

  • Create a shared Google Drive folder where we can put assignments and examples of student work (access limited to faculty involved in the group).
  • Organize another meeting for next quarter. People were pleased enough by the meeting to want to meet again.

I don’t think that anyone will make any radical changes to how they teach as a result of the meeting, but I think that several of us came away with the nugget of an idea for a small improvement we could make. It was also very refreshing to have a discussion of teaching techniques—something we professors don’t often get a chance to engage in meaningfully.  Most attempts to foster such discussions are way too broad (like the Academic Senate teaching forums) in an attempt to include everyone, or way too bureaucratic (like the attempts of the administration to push assessing “program learning outcomes”).  Today’s informal discussion seemed to me to be focused enough to be productive, yet broad enough to involve many different courses.  I’m looking forward to doing it again next quarter.

2015 November 5

Book draft 2015 Nov 5

Filed under: Circuits course — gasstationwithoutpumps @ 22:39
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I released an updated version of the Applied Electronics for Bioengineers text today.  This draft involved several changes:

  • Added modifier for “resistor” at end of Section 5.1
  • Changed “load resistor” to “bias resistor” in microphone chapter and lab.
  • Fixed microphone schematics to use polarized microphones.
  • Figure 11.2 changed to use only one differential channel on PteroDAQ.
  • Brief explanation of RMS added to Section 3.2
  • Small fixes to Chapters 9–16 and indexing terms added.
  • Index cleaned up.
  • 60Hz FM figure added to Chapter 14
  • Updated power discussion in Sections 0.5, 12.3, 23.1
  • Updated to include Teensy 3.2
  • Major rewrite of Chapter 23 (Class D power amp)

I’m still not finished with the Class D chapter, but I managed to test today an H-bridge circuit using a 9V power supply, which could provide ±9v signals to a loudspeaker (the full 10W that the loudspeaker can take).  I did not actually drive the loudspeaker that far, but I confirmed that the H-bridge was providing the full voltage range for PWM and that I was getting clean signals at the loudspeaker for loudness I was willing to tolerate listening to.

I’m now convinced that an H-bridge design is a simpler approach to teach the students, as well as being more useful for students who go on into the “assistive technology: motor” concentration.  Modifying the H-bridge to use logic-level signals from the comparator but high voltages for the power FETs turned out to be quite simple.  I just added a small nFET and a couple of resistors to make an inverter with a small voltage swing on the output:

Q1 and the resistors R1 and R2 form an inverter for driving the pFET.  Sizing R1 and R2 determines the voltage swing on the pFET gate  (Q2) and how fast the turn on and turn off are.  Of course, when Q3 is on, there is a current through it that is wasted (not delivered to the load), but I was able to keep that down to about 15mA.

Q1 and the resistors R1 and R2 form an inverter for driving the pFET. Sizing R1 and R2 determines the voltage swing on the pFET gate (Q2) and how fast the turn on and turn off are. Of course, when Q3 is on, there is a current through it that is wasted (not delivered to the load), but I was able to keep that down to about 15mA.

2015 September 7

Book draft 2015 Sep 7

Filed under: Circuits course — gasstationwithoutpumps @ 18:33
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I released an updated version of the Applied Electronics for Bioengineers text today.  This draft involved several changes:

  • Minor improvements to title page and copyright page.
  • Acknowledgements page added.
  • Various minor fixes in the Preface and Chapters 0–7, including more indexing.
  • Added figure and explanation of series and parallel connection to Chapter 0.
  • Added background info on capacitors and complex numbers to Chapter 0.
  • In Lab 1, fixed some PteroDAQ references to mention the Teensy boards.
  • Table of capacitor values added to Chapter 7.
  • Added an exercise to RC filters (Chapter 8)
  • Added an exercise to voltage dividers (Section 5.2)
  • Added PDF bookmarks for contents, list of figures, list of tables, bibliography, and index.
  • Cleaned up bibliography and added a few entries.
  • Protoboard design put online ( and properly pointed to.
  • Microphone preamp photo added to Lab 7.
  • In Chapter 18 (Pressure sensors), I collected new cuff-pressure data and added descriptions and pictures of the breath-pressure apparatus (plus breath-pressure data).  The new cuff-pressure data is more consistent with my normal blood pressure.
  • Chapter 19 (Instrumentation amps) lightly edited.
  • Lab 8 (pressure sensor lab) has had more scaffolding added to the sensitivity calculations.
  • Chapter 21 (Optoelectronics) extensively edited.
  • Added mention of isolation to Chapter 27 (EKG)

2015 August 28

Book draft 2015 Aug 28

Filed under: Circuits course — gasstationwithoutpumps @ 21:09
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I released an updated version of the Applied Electronics for Bioengineers text today.  This draft involved several changes:

  • I moved the electrode chapter and electrode lab to just before the EKG lab. This makes more sense in terms of the flow of the course, and means that the electrode lab can be done during the shortened Memorial Day week. The microphone, loudspeaker, and first audio-amp lab are now closer together, making a more coherent cluster (the hysteresis lab is still between the loudspeaker lab and the audio-amp lab). Unfortunately, the change also means that the introduction to op amps gets squeezed a bit, as the first audio-amp lab is a week earlier.  I’ll see how well that works this spring, and whether some other adjustment to the schedule is needed.
  • The hysteresis and relaxation oscillator chapter and lab were rewritten to take advantage of the frequency-measurement channels added to PteroDAQ. I replaced the old frequency recording with one done using PteroDAQ, and I added discussion of how to do the lab without bench equipment. I think that these chapters are essentially done,
  • The protoboards for using op amps came this week, so I took photos and put them in the audio-amp lab:
    Front and back of op-amp protoboard. This board replaces the instrumentation-amp protoboard used in previous years. Students will solder two boards: a microphone preamp and an EKG.

    Front and back of op-amp protoboard. This board replaces the instrumentation-amp protoboard used in previous years. Students will solder two boards: a microphone preamp and an EKG.

    I think that the new protoboards will be easier for students to use than the old ones—the grouping of wires is more obvious, there are more dedicated resistor slots, and each resistor can now connect to two wires at each end.

  • I also added a picture to the power-amp chapter of a bread board that I had melted by getting an nFET too hot:

    Too much current through a nFET can make it hotter than a breadboard can handle.

    Too much current through a nFET can make it hotter than a bread board can handle.

  • Throughout the book I changed references to the KL25Z board to references to the FRDM-KL25Z, as that seems to be the official part number for the development board.

At this point, I’ve rewritten and updated through Chapter 17, and I still have Chapters 18 through 28 to go.  It looks like I won’t get a full pass over the book done this summer

Work on the book and PteroDAQ will slow down somewhat for the next few weeks as I take care of other pressing deadlines: my teaching/research/service statement and biobib for a merit review—it’s been 4 years since the last time I did them; an external review for tenure of an assistant professor; final approval of PhD thesis that I read earlier this summer; finalizing the H. pylori genome assemblies I’ve been working on; setting up my web sites for fall quarter; planning the schedules for both my fall quarter classes; ophthalmologist appointment; training session for undergrad peer advisers; School of Engineering “all-hands” meeting; … .

I’ve spent about 4–5 hours on the external review so far, and have only read the CV, research statement, and two of the papers—there are five more papers to read, so I figure it will take me about 10 more hours to read the remaining papers and synthesis a coherent 1–2-page letter supporting (or not) the tenure case.

The thesis is a less difficult task, as I’ve already read the whole thing and marked it up—all I have to do is check that the corrections and clarifications I requested have been made.  I expect that to take 4–8 hours.

One problem is that both the tenure review and the thesis checking are tedious, so I can’t do them for very long at a time—but both are due next Wednesday. Writing the teaching/research/service statement will take some effort, as I have never been good at the bragging that seems to be expected—I tend to write honest statements of what I’ve been doing, which then get misinterpreted as my having been much less successful than what a straight reading of the material says.

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