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2013 July 6

Disseminating the applied circuits labs

Filed under: Circuits course — gasstationwithoutpumps @ 11:41
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The post I just published about academic conferences lead me to thinking (again) about how I should disseminate my course design (or individual lab designs) for the Applied Circuits course.  I suppose I should write up a paper and submit it to a conference or some journal like the Journal of Engineering Education.

One problem is that my course designs are not education research—they are attempts to solve particular curricular problems by taking advantage of my strengths as a teacher.  Some of the course design generalizes to other teachers and other institutions with somewhat different curricular needs, but there is no controlled experiment to say that my course design is “better” than another is some predefined, measurable way.

I’m not sure where this sort of here-are-some-good-ideas-you-may-be-able-to-use course design work fits in academic publishing.  If I were teaching physics, I would probably submit to The Physics Teacher, but I don’t know what the closest equivalent is in engineering—particularly interdisciplinary stuff like teaching circuits to bioengineers.  There don’t seem to be good journals intended for disseminating instructional labs and curricular design. Maybe Advances in Engineering Education would be a better fit than Journal of Engineering Education, even if I don’t feel that my course design contains “significant, proven innovations in engineering education practice, especially those that are best presented through the creative use of multimedia.”

Of course, distilling down the 200–400 pages of notes on my circuits course that I’ve collected on this blog to a conference presentation or a journal article is a daunting task—one that I’ll probably keep putting off until it is so stale that even I’m not interested in it any more.  It might even be easier to turn the notes into a book than into an article, since I would not have to do 100-to-1 compression.

I’m not sure who the right audience for such a book would be—instructors trying to create a new course, students taking my course, hobbyists wanting to learn the material at home, … ? That is, should I be writing about a case study in course design, should I be trying to create a textbook for the course, or should I be trying to put together a self-study book that could accompany a kit of parts for people to learn electronics at home?

Again, the book project is big enough that I’d probably keep putting off indefinitely.  If I was sure there was an audience, I’d be more inclined to put in the effort to disseminate the material beyond this blog, though.

Another approach for disseminating the course materials would be to put together stand-alone kits for each lab (with detailed tutorials) that could be sold independently.  Releasing one lab at a time would be a more incremental effort than doing all 10 labs in one package, but would require some redesign, both for reduced expectations of lab equipment and to make the kits more modular.

I suspect that one could do most of the experiments of the circuits course for about $360 in lab equipment and tools, using something like the Velleman Lab2U unit (which PartsExpress sells for $210), a $40 multimeter,  a $17 soldering station, an Arduino, and the $66 bag of tools and parts I put together for the course.  The Lab2U is only a single power supply, so some of the projects that used a multiple supply would need to be redesigned—most notably the class-D power amp.  Unfortunately, $360 is too big a chunk of money for anyone but a dedicated hobbyist, who quite likely already has most of the needed equipment.

Making the kits more modular might be difficult. For example, many of the labs require students to choose resistors and capacitors from a large set of possibilities, since their lab kit contained 10 each of 112 different resistors and 10 each of 25 different ceramic capacitors.  It is easy to justify the cost of those parts spread over 10 labs, but harder to provide that much selection for a single lab.  Perhaps one would have to sell a core kit (with breadboard, resistors, capacitors, …) to use with the Arduino and add-on kits for each lab.  The core kit would need to have some fundamental experiments (like RC time constants), so that it would be instructional even without add-ons.

I wonder if there is a market for such lab kits, and how I would find out if there were a market (without sinking months of my time and thousands of dollars). I wouldn’t want to assemble or market the resulting lab kits either, but would want to distribute them through a company like Sparkfun electronics, Adafruit Industries, or Seeedstudio, who have already set up the necessary business infrastructure.

I also wonder whether I’m capable of writing the tutorials at an introductory enough level to work for hobbyists, while still covering enough of the theory.  I’ve never cared for kits that have great assembly instructions, but treat the way the things works as too difficult for the purchaser of the kit.

Writing instructions that included the use of an oscilloscope or multimeter, when there are many different ones that the person may be trying to use, would be a very challenging task.  Oscilloscopes in particular have evolved to have many radically different user interfaces, some of which are very complicated.

Also, all my writing has been for well-educated people: college professors, university students chosen from the top 10% of high school students, my loyal blog readers, … .  Can I make my writing intelligible for an average, or slightly above average, high school student, without sounding condescending or patronizing?  From the rather unsuccessful attempts I’ve seen in kit instructions in the past, that is not an easy task.

2012 September 2

Wikipedia books, another approach for a free/cheap textbook

Filed under: Circuits course — gasstationwithoutpumps @ 14:06
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I’ve been thinking about another approach to providing a low-cost textbook for the circuits class: bundling a number of Wikipedia articles into a Wikipedia book, like the Introduction to Electronics one.  The idea is an appealing one, as many of the Wikipedia articles are excellent (better written than many textbooks), we can customize what topics to include, small errors in the text can be corrected, and students can either access the “book” online, download it in in PDF, ZIM, or OpenDocument format, or even pay for a printed copy.  The downloaded or printed copies will be frozen, while the live Wikipedia book gets updated every time one of the contained articles is edited.  We could provide frozen copies on the course web site, as a precaution against major rewrites removing information we expect students to read.

The Introduction to Electronics Wikipedia book does not have exactly the subjects we would need for our course, but several of the articles there are appropriate.  One attraction of this approach is that we can tailor our book to have exactly the content we need (assuming the articles we need exist) in the order we want. We can design our course by listing the topics we need in the order we need, and automatically have a text that matches. Given the somewhat idiosyncratic nature of our course (from basic circuits to EKG design, with side trips into electrodes and possibly fluidics modeling), we’re going to have to cobble together multiple sources anyway, so a Wikipedia book may be a good way to create the main text.  No matter what text we use, we’ll have to supplement with manufacturers’ data sheets, which can’t be included in a Wikipedia book because of copyright restrictions.

One disadvantage of Wikipedia books is that the articles in Wikipedia are by different authors and have no implicit ordering, so concepts cannot be developed in a gradual manner.  Individual articles are written at very different levels of sophistication, and some articles will have only a few sections that are relevant to the course.  The book would not be as smooth as a well-written textbook, but better than many of the poorly written ones on the market. I believe that we can add some manually created text (part of the book, but not part of Wikipedia) to introduce chapters, but I’m not exactly sure how (probably it involves including pages that are part of Wikipedia user space rather than public space).

Note: Wikipedia books are different from WikiBooks, which are from a project to create crowd-sourced free textbooks.  The electronics books currently available from WikiBooks are very incomplete and not as well written as Wikipedia articles, so I don’t think that they will be useful this year.

I started playing a bit with Wikipedia’s “Book Creator” and found it to be a very awkward interface.  Clicking on pages to add them to the book being created worked ok, but dragging the pages around to reorder them did not and the claimed button for adding chapters never appeared.  Furthermore, once you save a draft book, the book creator assumes you want to start a new one, so clicking on pages can’t add to an existing draft.  It seems that the book creator is damn near useless after the first 5 minutes, and after that you just have to edit the book like any other Wikipedia page.

2012 August 31

All about circuits, a possible supplemental text

Filed under: Circuits course — gasstationwithoutpumps @ 22:54
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I’ve been dipping into All about circuits, a free electronic textbook written (mostly) by Tony R. Kuphaldt, as a possible textbook for the circuits class.  I like that it is free, as that makes it much more likely that students will have ready access to it (many decide not to buy expensive texts, and end up trying to borrow them from friends).

The format, as 100s of HTML files, is a bit awkward to read, but fairly easy to search with Google (by adding “” to the keywords ins the search box), so indexing is not really an issue.  The book starts at about a middle-school level, but gets up to the beginnings of circuit theory (Thevenin’s TheoremRC and L/R time constants, Reactance and impedance—R, L, and C, …).  The Operational amplifier chapter looks usable, though it does not have a design focus—circuits are presented as almost magical rather than carefully analyzed from first principles (as is done in more theoretical circuits books) or from design rules of thumb (as is done in books like Horowitz and Hill).

I think that All about Circuits can be a good supplemental text for students who need something at a lower reading and math level than Horowitz and Hill, for review of physics electricity and magnetism concepts, and to fill in gaps in prior education (such as complex numbers).

I don’t know that I want to use Horowitz and Hill as the main text, though, as it is pretty expensive for such an old electronics book. I wonder if there is another free book that is somewhat higher level than All about Circuits that can be combined with it to make a textbook at the right level for the range of students expected in the class.

I think we may need a more mathematical presentation of some of the material, if the students are to be able to continue into later electronics classes. This may not matter, because the chair of the EE department has made it pretty clear that no subsequent electronics course would use this course as a prerequisite, and that students would have to take the “real” circuits course in order to take any further electronics courses.  Of course, if he holds to that for the bioelectronics class, then he’ll have almost no students in that class, since few if any of the bioengineers will subject themselves to the dry, repetitive linear algebra manipulations of the standard circuits class in order to take a bioelectronics class that doesn’t even include a lab component.  If we get to teach our applied circuits course, we should be able to convince the professor creating the bioelectronics course to accept it as a prereq in place of the standard circuits course.

2012 August 21

Possible textbook, Horowitz and Hill

Filed under: Circuits course — gasstationwithoutpumps @ 21:54
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Having rejected Medical Instrumentation: Application and Design, 4th Edition. ISBN-10: 047167600 as being unsuitable for the circuits class, despite some relevant material, I decided to start looking from a different angle.  Instead of looking for a text targeted at bioengineers that talks about circuits for EKGs, I decided to look for one that covered basic circuits material with the appropriate applied emphasis, even if the application were different.

I started by looking at a classic EE textbook, The Art of Electronics, 2nd edition by Paul Horowitz and Winfield Hill (copyright 1989) ISBN-10: 0-521-37095-7 hardback 0-521-42228-0 paperback.  Amazingly this 23-year-old electronics book is still in print and still sells at high prices  ($97 new and $70 used at Amazon). I was rather hoping that such an ancient book would have gotten cheap by now, but it seems to have retained its value better than just about any other EE I’ve heard of.

I understand that a third edition was scheduled for March 2012 and is now expected in early 2013.  Given the extensive lists of parts in the book, many of which are long gone from the market, such an overhaul is way overdue.  Perhaps the best thing they could do is throw out Chapters 10 and 11 (on microcomputers and microprocessors) as impossible to maintain and concentrate on the stuff that remains more stable for decades, since the 3rd edition is undoubtedly going to be the last one.

I’ve read the first 30 pages of Chapter 1: Foundations, and it seems to have exactly the right mix of practical advice with theoretical underpinnings for the applied circuits course.  It even starts with exactly the topics we thought to start with—resistance and voltage dividers, followed by impedance and generalized voltage dividers.

We can’t use all of the book in a 10-week course, but it looks like we can skip Chapters 2 and 3 (on bipolar and FET transistors respectively) and jump immediately to Chapter 4 on op amps.  I think that we should also use scattered sections from later in the book (like on voltage references, instrumentation amplifiers, and noise in amplifiers).  I’ll have to go through the book carefully to figure out how much of it we can use, and whether that is enough to justify the $70–100 price to the students.  Based on a quick look through today and reviews by people who have used the book, it seems likely that this is a book to encourage students to buy and keep.

There are a number of Amazon reviewers who disliked the book—most were trying to teach themselves electronics using the book and found the explanations too terse without a professor or TA to answer questions and expand on the material. Since we will be available, those criticisms are not really relevant for a course textbook, though it is good to know that some students find even the intro material daunting, and so we should have a slower-paced, more tutorial option available for such students.

Before I dive too deeply into Horowitz and Hill, I’ll also look into the recommendations of intro books by “Wise Warthog”, who gives a number of different suggestions for people with different needs.  He recommends a free e-book Lessons In Electric Circuits  by Kuphaldt for those just getting started, but warns that it may be too slow for some people, and suggests alternatives.



2012 August 19

Medical Instrumentation, Chapters 9–14

As I mentioned in Medical Instrumentation, first 5 chapters, Medical Instrumentation, Chapter 6,  and Medical Instrumentation, Chapters 7 and 8, I’ve been slogging through one of the potential text books for the circuits course: Medical Instrumentation: Application and Design, 4th Edition. John G. Webster. Publisher: Wiley, 2009. # ISBN-10: 0471676004; # ISBN-13: 978-0471676003.  Here are my notes on the rest of the book (I plan to return it tomorrow to the library).

Chapter 9

Frank P. Primiano, Jr.

I only skimmed chapter 9, as there did not seem to be much of use for the circuits course.

Richard had suggested making a rotating-vane flowmeter using a toy siren-whistle as the turbine and a photodetector to determine its speed.  I investigated that possibility, but the siren whistles have very low drag on their turbines and continue to spin for a couple of seconds after the air flow has stopped.  One might be able to use that for a wind-speed indicator, but the response time is far too slow for measuring air flow due to breathing.

The section on measuring gas concentrations is intellectually interesting and may be of some value to bioengineers, but doesn’t seem relevant for the circuits course.

Chapter 10

Robert A. Peura

It’s nice to know how a pH probe works and how blood gases are measured, but I don’t see a lot we can do in the circuits class.
The plot of the absorptivities of carboxyhemoglobin, oxyhemoglobin, reduced hemoglobin, and methmoglobin in Figure 10.6 are interesting, and are needed for explaining how a pulse oximeter works, as well as why 940nm LEDs should be a good choice for detecting arterial blood pulses, since reduced hemoglobin has about 3/5th the extinction coefficient of oxyhemoglobin there.  An even longer wavelength (say 1000nm) would be even better, since the ratio drops to about 1/4, if LEDs and phototransistors for that wavelength were readily available, but 950nm is about as long a wavelength LED as is available.

I considered doing a pulse-oximetry lab, but the difficulty of calibrating the device made it seem pointless.  That’s too bad in a way, as the technique relies inherently on considering the AC rather than the DC component of the signal.

Chapter 11

Lawrence A. Wheeler

Nothing in this chapter seems relevant to the circuits class.  I had at one point considered doing a very early lab in which electric fields were illustrated by measuring voltages at different points in an electrophoresis gel, but that didn’t seem worth the messy setup.  Most of the bioengineers will do gel electrophoresis in other labs anyway.

Chapter 12

Melvin P. Siedband

Nothing in the imaging chapter seems relevant for the circuits class.

Chapter 13

Michael R. Neuman

It doesn’t look like there is anything in Chapter 13 for our course.

Chapter 14

ELECTRICAL SAFETY                               638
Walter H. Olson

14.1       Physiological Effects of Electricity   639

Useful figure and definitions of different levels of shock hazard.

14.2       Important Susceptibility Parameters   641

Perhaps a bit too much information for students to process about current needed for hazard.

14.3       Distribution of Electric Power   646

Fairly straightforward description of electric distribution in buildings.  Students should know this already, but most likely don’t.

14.4       Macroshock Hazards   650

Somewhat wordy description of hazards, repeating previous sections.

14.5       Microshock Hazards   653

Important for those who are making direct electrical connections to the heart, which we are NOT.

14.6       Electrical-Safety Codes and Standards   658

As boring as the title makes it sound.

14.7       Basic Approaches to Protection Against Shock   659

Short and nearly contentless.

14.8       Protection: Power Distribution   660

Good description of GFCIs, but the schematic in Figure 14.15 is not explained, and how it works is not obvious.

14.9       Protection: Equipment Design   663

Reasonable description of double insulation and isolation barriers.  Doesn’t seem to indicate that optical couplers are now the dominant method (though I believe they are) for information transfer across the isolation barrier—they give it only as one of three possible options.

14.10     Electrical-Safety Analyzers   667

One paragraph, not much content.

14.11     Testing the Electric System   667

Doesn’t really say how to do it, just that the usual 3-LED tester used by construction workers and home electricians is inadequate.

14.12     Tests of Electric Appliances   669

Basically repeats material from the National Fire Protection Association standards (NFPA99-2005).

Problems   673
References   674

Chapter 14 has some good material on electrical safety, but is probably too much information for the circuits course.  I’m going to have to find a more concise description that students will actually read and remember.

Bottom line

There are bits and pieces of Medical Instrumentation that could be useful to our students, but not enough of the content is relevant to the course to use it as a text and the parts that are relevant are too long for the book to be useful as a reserve book in the library.  It was probably worth my time to read (most of) the book, but I doubt that it will be worthwhile for the students.

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