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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.

2015 August 11

Leanpub is a very small publisher

Filed under: Circuits course — gasstationwithoutpumps @ 06:57
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I like the Leanpub model for publishing uncompleted works, and I’m happy I found them, but they are still a very small publisher.  They claim

So far our authors have earned over $2.9 million in royalties, and readers have downloaded over half a million books. []

Their top-selling book has sold fewer than 35,000 copies (including free copies), and 10th on their list has fewer than 11,000.  Their full list has just under 2700 different books, and the median number of sales is 10.  I’m already in the top half of their list for sales! Almost all the top sellers are associated with MOOCs (massively open online course)—they use the book as a text for their MOOC, often available for free with a low suggested price.  It does seem like a good way for distributing a textbook for a MOOC.

It is a bit harder to see the distribution of earnings—though they list the bestsellers by lifetime earnings, they don’t say what those earnings are.  I estimate that their top-grossing book earned the author about $120,000 and the 10th highest about $70,000.  Of course, these numbers may be over-estimates, as I can only see the total number of readers and the minimum price, not the actual earnings.  I have no idea where the draft of my book (Applied Electronics for Bioengineers) is in the total earnings list—probably somewhere near the middle also.

My book is the only electronics book on their list (at least, the only one that comes up with a search for “electronics”—they have a very, very limited search capability).  Many of their books are computer science or programming books, but “computer” yields only 7 books and “programming” only 46.  I’m not sure what they are indexing for the search—perhaps the landing-page blurb?  Nope—my book doesn’t get found using “amplifiers”. It seems like they are only indexing title and author, and maybe subtitle.  I’ve sent them e-mail suggesting that they index the landing-page blurbs as well.

I doubt that selling through Leanpub will ever get me up even to minimum wage on the effort put into writing the book, as I don’t have an advertising channel like a MOOC to direct people to the book.  But the main point of the book has been to support the students in my class and to encapsulate the course so that someone else can teach it when I retire, not to make money from it.

It’d be nice if I could get a wider readership, but I’m not working too hard on getting one.  My main effort in that direction is to try this summer to make all the labs be doable with minimal lab equipment: the goal is to have all the parts and tools needed to do everything at home come to under $200. I think that is now feasible, but only about half the labs have been rewritten to include the low-cost approach—a lot still rely on the expensive bench equipment we have in the circuits lab on campus.


2015 June 4

Last lab of Spring 2015

Filed under: Circuits course — gasstationwithoutpumps @ 22:50
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I spent all day today in the lab for the electronics class, from around 9:30 a.m. until the last students packed up and left at 8:30 p.m.  This was the last lab of the quarter, and I had decided to stay until all the students had left.

Most of the students got their EKG boards soldered up and working today (there may be a few who left without demoing their working boards, and the last group at 8:30 p.m. had just had some more wiring errors pointed out to them).

I’m amazed sometimes at how basically competent designers can be very careless in their wiring, rushing through the placement and soldering without carefully checking each connection. The result is a 10-minute savings in wiring time, and a 4-hour or more cost in debugging and resoldering time.

Tomorrow in class I plan to go over a couple of 1-transistor amplifier designs, but that shouldn’t take the whole time.I’ll give them some pointers to companies that sell parts and kits that might be of use to them: Digikey, Mouser, Jameco, Sparkfun, Adafruit Industries, Itead Studio, Seeedstudio, Smart Prototyping, Elecrow, OSH Park, Makershed, … . And I’ll be sure to mention some local resources: Santa Cruz Electronics and Idea Fab Labs.

I also hope to remind the students of some of the goals of the course, and try to see whether the goals have been met.  I quote from the supplemental form for the course renaming that was approved this spring (effective next year).

The Program Learning outcomes for the bioengineering program are as follows:
A bioengineering student completing the program should

  • have a broad knowledge of science and engineering disciplines including biology, chemistry, physics, mathematics, statistics, and computer science; [Not relevant to this course]
  • be able to apply their broad knowledge to identify, formulate, and solve engineering design problems; [Students passing BME 101L will be able to design simple amplifiers and RC filters for a variety of sensor-interfacing applications.]
  • be able to find and use information from a variety of sources, including books, journal articles, online encyclopedias, and manufacturer data sheets; [Students passing BME 101L will be able to find and read data sheets for a number of analog electronics parts.]
  • be able to design and conduct experiments, as well as to analyze and interpret data; [Students passing BME 101L will be able to measure signals with multimeters, oscilloscopes, and data-acquisition devices,  plot the data, and fit non-linear models to the data.]
  • be able to communicate problems, experiments, and design solutions in writing, orally, and as posters; [Students passing BME 101L will be able to write coherent design reports for electronics designs with block diagrams, schematics, and descriptions of design choices made.] and
  • be able to apply ethical reasoning to make decisions about engineering methods and solutions in a global, economic, environmental, and societal context. [Not relevant to this course]

So tomorrow I plan to ask where the students feel that they are able to design simple amplifiers and RC filters, whether they can find and read data sheets for analog parts, whether they can measure signals with multimeters, oscilloscopes, and data acquisition devices, whether they can plot the data and fit non-linear models to it, and whether they can write coherent design reports.

I had some unofficial goals for the course also: to turn a few of the students into electronics hobbyists, to encourage a few to declare the bioelectronics concentration of bioengineering, to teach some tool-using, maker skills (calipers, micrometer, soldering iron, …), and to make all of them better at attacking problems by dividing into subproblems with clear interfaces between the subproblems.  I’ll ask about those things also.

I’ll also want some detailed suggestions for the course.  (So far I’ve gotten one: fume extractors for the lab for use when soldering.)  Some things I’m curious about include

  • Should the first amplifier lab (the low-power audio amp lab) be changed to use a single power supply and solder up the board, so that the board can be used as a preamp for the class-D power amp lab later?  We could then also do an emitter follower (common collector) class-A amplifier using the preamp board.  If they solder up a pre-amp, then we could eliminate soldering the instrumentation amp for the blood pressure lab.
  • Should I redesign the prototyping board to have more room for resistors and no instrumentation amp slot, making it more suitable for the preamp lab and the EKG lab?  A new custom board is still cheaper than something like the $4 perma-proto boards from Adafruit.
  • Should I switch from 18-turn trimmer pots to 3/4-turn trimmers with shafts?  The ones with shafts tend to be easier to turn, but not as precise and the multi-turn worm gear pots.  There are 3/4-turn trimmer pots that play nicely with a breadboard, though they take up a bit more space than the worm-gear trimmers we used this year.
  • Are there tools or parts that almost no one used?
  • Are there tools or parts that should be added to the lab kit? If so, at what price do they stop being attractive?
  • Should students buy oscilloscope and voltmeter probes, like they do at UCSB, rather than having to deal with broken probes or probes locked inconveniently to equipment?
  • Should there be more practice questions in the book? (currently I have very few, with almost all the questions being part of prelab assignments)
  • Does there need to be a “what you are already expected to know” section or chapter, to review material that students are supposed to know already?
  • Which labs took up too much time for the amount of learning achieved? How can they be streamlined?
  • How much time did the course really take total for the quarter?
  • What suggestions do students have for more fun labs?

2015 March 27

Bogus comparison of Word and LaTeX

Filed under: Uncategorized — gasstationwithoutpumps @ 09:36
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An article was recently brought to my attention that claimed to compare LaTeX to Word for preparing manuscripts: PLOS ONE: An Efficiency Comparison of Document Preparation Systems Used in Academic Research and Development. The authors claim,

To assist the research community, we report a software usability study in which 40 researchers across different disciplines prepared scholarly texts with either Microsoft Word or LaTeX. The probe texts included simple continuous text, text with tables and subheadings, and complex text with several mathematical equations. We show that LaTeX users were slower than Word users, wrote less text in the same amount of time, and produced more typesetting, orthographical, grammatical, and formatting errors.

It turns out to be a completely bogus study—they compared typist or typesetting tasks, not authoring tasks. There was no inserting new figures or equations into the middle of a draft, no rearranging sections, no changing citations styles—not even any writing—just copying text from an existing typeset document. It is very misleading to say that the “LaTeX users … wrote less text”, as none of the subjects were writing, just copying, which uses a very different set of skills.

I don’t think that there is much question that for simply retyping an existing document, a WYSIWYG editor like Word is better than a document compiler like LaTeX, but that has very little to do with the tasks of an author. (And even they noted that the LaTeX users enjoyed the task more than the Word users.)

For those of us who use LaTeX on a regular basis, the benefits do not come from speeding up our typing—LaTeX is a bit slower to work with than a WYSIWYG editor.  The advantages come from things like automatic renumbering of figures and references to them, floating figures that don’t require manual placement (except when there are too many figures—then having to do manual placement with LaTeX is a pain), good math handling, automatic formatting of section and chapter headings, being able to define macros for commonly used actions, and the versatility of having a programming language available. For example, I have a macro that I like to use for proper formatting of conditional probability expressions, and another that I use for references to sections, so that I can switch between “Section 3.2”, “Sec. 3.2”, and “§3.2” through an entire book with a change to just one line in the file.

LaTeX also has the advantage of having a much longer life span than Word—I can still run 30-year-old LaTeX files and print them, and I expect that the files I create now will still be usable in 30 years (if anyone still cares), while Word files become unusable in only 10-to-20 years.  LaTeX is also free and runs on almost any computer (the original TeX was written for machines that by modern standards were really tiny—64k bytes of RAM).

For those who want multiple-author simultaneous access (like Google Docs), there are web services like that permit multiple authors to edit a LaTeX document simultaneously. I’ve used with a co-author, and found it to be fairly effective, though the server behind the rendering is ridiculously slow—40 seconds for  a 10-page document on the web service, while I can compile my whole 217-page textbook three times in about 12 seconds on my 2009 MacBook Pro.

Like the emacs vs. vi wars, the LaTeX vs. Word camps are more about what people are used to and what culture they identify with than the actual advantages and disadvantages of the different tools. Bogus studies like the one in PLoS One don’t really serve any positive function (unless you happen to be a monopoly software seller like Microsoft).


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