I’ve finally finished my grading for the quarter, after a solid week of grading, and so I can now catch up on some of my administrative tasks (like checking the articulation framework documents, trying to find an undergraduate director for bioengineering for Fall quarter, checking the 30 or so senior exit portfolios, and so forth).
I can also start thinking about the tasks for me on revising my book, which will take up big chunks of summer and fall:
- Move the book files into a source-code control system, probably mercurial, and use and off-site backup, probably BitBucket. I should have had the files in a source-code control system from the beginning, but I never got around to setting it up. This is a couple of years overdue, and I shouldn’t make any more updates to the book until I’ve done it.
- Rearrange book to put labs in new order, moving all the audio labs into the second half, and moving the instrumentation amplifier and transimpedance amplifier into the first half.
- Revise parts list for next year’s labs.
- May want to use a different phototransistor (without the filter that makes it less sensitive to visible light).
- Choose nFET with lower threshold voltage (maybe pFET also).
- Find better resistor assortment.
- Add hobbyist add-ons to the labs, for people who want to go beyond what we can do in class. For example, I could add
- designing a triangle-wave generator to the class-D amplifier, so that it can be self-contained,
- sound input from a phone jack to class-D amplifier (with info about TRRS plugs)
- logarithmic transimpedance amplifier for optical pulse monitor, to make it tolerant of different light levels and finger thicknesses
- optical pulse monitor using reflected (actually back-scattered) light instead of transmitted light, so all the optics is on one side
- motor controller based on H-bridge used in class D
- temperature controller using thermistor, FET, and power resistor
- galvanic skin response measurement?
- oscillator design other than Schmitt trigger relaxation oscillator? Maybe a Colpitts oscillator with the big inductor (though even with 10μF and 220μH, the frequency would be rather high for audio use)?
- make Schmitt trigger out of comparator chip
- EMG controller (either with analog envelope detection or with software envelope detection)
- Insist on LaTeX for design reports. I had too many reports with terrible math typesetting, incorrect figure numbering, and bad font substitutions with Microsoft Word or Google docs reports. I’ll need to include a short tutorial in the book, with pointers to more complete ones.
- Make it clear in the book that design reports build on each other, but each report needs to be self-contained—for example, the class-D amplifier report should contain circuits, results, and some discussion from the microphone, loudspeaker, and preamp labs; and the EKG lab report should include some information from the blood pressure and pulse monitor labs.
- Add more background physics and math at the beginning of the book, to review (or introduce, for some students) topics we need.
- Should I add a short lab characterizing the I-vs-V curve for an nFET and a pFET? If so, where would I fit it in? What about for a diode (could be LED)?
- Bypass capacitor discussion should be moved to between the preamp lab and the class-D lab. I need to talk more about power routing and location of bypass capacitors for the class D lab (it is important that the bypass capacitors be between the the noise-generating FETs and rest of the circuitry, which is noise-sensitive). May need to introduce the concept of the power wiring not being a single node, so that “clean 5V” and “dirty 5V” are different nodes.
- Class-D lab should have students measure and record the amount of current and power that their amplifier takes with no sound (removing the mic?) and with loud sound input, both with and without the LC filter.
- Class-D lab should require students to show oscilloscope traces of the gate and drain of an nFET and of a pFET in the final H-bridge, both for turning on and for turning off.
- EKG, blood pressure, and pulse monitor prelabs should have students compute the attenuation of 60Hz interference (relative to the signal in the passband) for low-pass filters that they design.
I should also review what students had to say about the course (look at discussion in previous post, for example).