Gas station without pumps

2012 July 18

Giving up on light-based pulse sensor

Filed under: Circuits course — gasstationwithoutpumps @ 16:16
Tags: , , , , , ,

I’ve pretty much decided against using the LED/photodetector pulse sensor as a lab.  The mechanical setup for aligning the optical components is too off-topic for a circuits class, and the amplifier design is no easier than the EKG amplifier, but not as useful educationally (since it doesn’t get to the notion of instrumentation amplifiers). The EKG has a better “coolness” factor also, and the EMG applications are directly relevant for some of the research projects the students could get into.

I still want to have a light-based sensor and some LED circuits in the labs, but I’m not sure exactly how to incorporate them.

I decided to try looking at labs for circuits courses I found on the web, hoping to find some inspiration.  The first few hits were pretty discouraging.  With labs as boring as these it is a wonder that anyone ever goes into EE:

  • MIT’s 6.002 analog circuits course has the most boring labs I could imagine.  These would definitely drive any bioengineer as far from EE as they could possibly go.  Although I have a warm place in my heart for digital FET circuits (I started my faculty career teaching nMOS and cMOS VLSI design), they are not the right material for bioengineering students.  Also, MIT seems to have only 4 labs in a semester. WTF? I’m looking for 10 labs in 10 weeks.
  • MITx’s circuits course has no labs, just simulation labs. Having done simulation and having worked with breadboard circuits and a real oscilloscope are totally different experiences.  On-line simulation does not provide real sensors, which is a big part of the impetus for the course we are creating.
  • UCSD ECE65has 10 labs, which sounds like the right number, but they are all 1 or 2 diodes or transistors.  Good for getting a very low-level view of circuits, but going to bore the hell out of any one who still needs to be convinced that electronics is relevant to them professionally:
    • Lab 0 – Introduction & Orientation
    • Lab 1 – Introduction to PSpice Simulations
    • Lab 2 – Diode IV Characteristics, Zener Diode
    • Lab 3 – Diode Waveform Shaping Circuits
    • Lab 4 – Transistor as a Switch
    • Lab 5 – Logic Gates
    • Lab 6 – Transistor Biasing & Current Mirror
    • Lab 7 – BJT Amplifiers
  •  University of Calgary ENGG 225Only 4 labs again, mostly pretty dull “determine the Thévenin equivalent of a resistor circuit” type:
  • Texas A&M ENGR111: 8 labs, informatively titled Lab1 through Lab 8. I would have looked at the lab, but at 3 minutes to download Lab 1 (ending up with just an irritating .doc file), I decided to look elsewhere.  I did look at Lab 2: KVL / KCL and DC Motor Modeling with Google’ quick look feature (much faster than uploading from TAMU).  The lab instructions were 19 pages of cookbook instructions and worksheets to fill out. The experiment of determining the effect on power consumption of adding drag to a motor is a reasonable one (though the setup for it is too detailed). I don’t think that motors are necessarily appropriate for our course, but it is something to think about adding.

    I hope that we don’t need to spell out instructions to that level of detail.  We probably should think about how we are going to verify that students have done the work of the lab, though—what exactly will they have to demo and what will they have to write up?

  • Mississippi State University PowerPoint presentation of hardware labs to do at home The basic idea, using a laptop as signal generator and oscilloscope, is good, if you assume that all students have Windows machines (software for USB oscilloscopes on Mac OS X is still hard to find). The construction techniques shown for the circuits looks even less reliable than using standard breadboards.  The circuits the students have to build look like OK op amp circuits, but not very exciting.
  • U Penn’s ESE 205 has 10 labs: 3 Arduino, 1 power charger, 2 op amp, and 4 RC and RLC circuits.  I was excited to see the Arduino in there, but it doesn’t seem to be integrated with the rest of the labs at all.  They just hook it up to servos and X-Bee transceivers and run pre-written programs on it.  Fun toy, but not all that useful for teaching circuits.

I glanced down the next several hits and was not seeing anything more promising.  Everything seems to be either trivial confirmation of circuit theory exercises or dry-as-dust op amp circuits.  Are there no beginning EE circuit courses with interesting labs?  That can’t be the case, but I’m having an awfully hard time finding them.  Stanford’s EE40 has a reasonable class description, but I have no access to the lab assignments, so I don’t know what they do in the lab (though the syllabus says “For [a] major portion of the quarter, you are expected to build and test your own audio amplifier.”    I looked at the Physics 160 course at UCSC also, but it seems to be too much transistor-level circuitry.  I’d like the students to use op amps as building blocks, not transistors.



  1. Not sure if this will be at all helpful, but have you looked at Neil Downie’s books? I doubt anything transfers directly, but maybe there is something that would provide useful inspiration. The books I’m thinking of are “The Ultimate Book of Saturday Science” and “Vacuum Bazookas, Electric Rainbow Jelly”, and there’s another book or two that I don’t recall.

    Comment by kcab — 2012 July 18 @ 17:37 | Reply

    • While I don’t have those books, I do have lots of similar resources (several years of Make magazine, CD ROM with the complete Amateur Scientist columns, an extensive set of Bernie Hutchins’s Electronotes, … ). The problem isn’t one of finding fun things to do, but finding ones that support the teaching of electronic circuits, that are doable in a single 3-hour lab session, and that would appeal to bioengineers. A lot of the fun projects either require too much time for non-electronics stuff or teach too little electronics.

      Comment by gasstationwithoutpumps — 2012 July 18 @ 17:42 | Reply

      • Well, I notice that you looked in straight EE courses for lab ideas. I doubt you’ll find anything that transfers wholesale to your use, but in MIT’s OCW I would look first under Biological Engineering and in general look for instrumentation and measurement courses.

        Comment by kcab — 2012 July 19 @ 18:36 | Reply

        • I’ll do that, but we’re trying to teach circuits, not the use of existing instruments, so I suspect I won’t find much relevant.

          Comment by gasstationwithoutpumps — 2012 July 19 @ 22:45 | Reply

  2. […] Giving up on light-based pulse sensor, I discussed the difficulty I was having in finding comparable courses to borrow ideas for labs […]

    Pingback by Looking at bioegineering measurements courses « Gas station without pumps — 2012 July 20 @ 22:14 | Reply

  3. […] Giving up on light-based pulse sensor […]

    Pingback by Order and topics for labs « Gas station without pumps — 2012 August 16 @ 23:39 | Reply

  4. […] and FET lab.  I mentioned some of the labs I had rejected (like the MIT lab on DNA melting or the pulse sensor), and mentioned some of the rather boring ones I had come up with.  Students expressed an interest […]

    Pingback by Eleventh day of circuit class « Gas station without pumps — 2013 February 2 @ 01:03 | Reply

  5. […] Giving up on light-based pulse sensor […]

    Pingback by New phototransistor lab | Gas station without pumps — 2014 March 16 @ 00:56 | Reply

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