Freshman Design: Table of Contents

This page collects all the blog posts for the development of my freshman design seminar. People interested in this may  also want to check out the posts for the Applied Circuits for Bioengineers class, which has projects more focused on electronic circuits (some requiring a bit more technical skill).

Because WordPress.com has an irrational prejudice against allowing oldest-first ordering of anything (or incompetent database programmers, which seems less likely), I’ve had to hand-create a table of contents for my posts about the design seminar. I would really love for them to have automatically generated “Table of Contents” summary pages for each category, giving the links to the posts and (optionally) the tags associated with the post.  Until they realize that not every reader and writer of blogs sees posts as being primarily valued by how recent they are, I’ll have to make do with this hand-generated table of contents (and remember to edit it every time I have a new post!):

1. New freshman design seminar This post introduces the course and provides the course description that I submitted for approval by the Committee on Educational Policy.
2. Optical pulse monitor with little electronics describes my experimenting with a possible project for the seminar.
3. Digital filters for pulse monitor describes adding digital filters in software to the optical pulse monitor.  A fun project, but probably too technical for a freshman course.
4. Failed attempt at pulse oximeter describes an attempt I made to convert the optical pulse monitor to a pulse oximeter.  I don’t have enough sensitivity or reliability of the mechanical design for this to work yet.  I think the project may be a bit too difficult for freshman bioengineers as a whole.
5. Towards automatic measurement of conductivity of saline solution describes another possible freshman design project: a conductivity meter using the KL25Z board.
6. Projects for freshman design seminar gives an overview of the projects I’ve thought about so far.
7. Electronic sensors for water quality lists four possible sensors and a pointer to a paper about using them as the basis for middle-school and high-school engineering/science courses.
8. Balancing fun and fundamentals discusses the problem of getting the interesting parts of any subject early, without abandoning the fundamental details that are sometimes a bit boring.
9. More on automatic measurement of conductivity of saline solution looks at waveforms for square waves generated using PWM on the KL25Z board.  In this post I found that 100kHz square waves would work well.
10. Still more on automatic measurement of conductivity of saline solution looks at waveforms for bursts of square waves generated by an Arduino board.  The bursts are limited to about 4kHz, but that may be good enough for a conductivity meter.
11. Using KL25Z for measuring salinity shows a program on the KL25Z that averages readings during the last 10,000 pulses of a 50,000-pulse burst.  It has Gaussian noise with a standard deviation of about 0.13mV on a 2.8v signal.  Jostling the electrodes is visible in the traces.
12. Range of conductivity measurements adds measurement of the applied voltage to the program (reducing the frequency to 65kHz) and checks the linearity of the conductance with concentration of NaCl, which is not very good on this simple 3-point measurement at 0M, 0.1M, and 1M NaCl.
13. First day of freshman design seminar discusses skills students bring to the class, based on the intake survey.
14. Second day of freshman design seminar discusses the design exercise I tried using a spectrometer as an example.  About all I managed to convey was that design is hard if you don’t know enough about what you’re designing.  Perhaps I should try an example next year that more students are familiar with—I thought that this would be a familiar concept (unlike, say, a polarimeter).  I was wrong.
15. Student forum and FERPA I’ve been planning to set up a student discussion group for the class.  What is the best way to do this, while respecting the University interpretation of FERPA?
16. First homework for freshman design points to the collection of web sites of ideas for DIY lab equipment found by the students.
17. Third day of freshman design seminar covers the creation on an e-mail discussion list for the class and lab tours.
18. Designing courses to teach design has notes for a lightning talk I need to give next week about the creation of this course (among other things).
19. Fourth day of freshman design seminar discusses the continuation of the spectrophotometer design exercise.
20. Designing courses to teach design—draft 2 gives a complete draft for the lightning talk (a couple days in advance of the talk itself).
21. Fifth day of freshman design seminar was spent looking in more detail at one part of the photospectrometer—the photodetector.
22. Actual homework on data sheets and photodetectors gives the assignment mentioned in the previous post.
23. Sixth day of freshman design seminar discusses the feedback on the first homework and reading a phototransistor data sheet.  Algebra and calculator skills were even lower than I expected.
24. Biomed lab tours and online discussions discusses the 7th day of class (lab tours) and the difficulty of getting an online discussion going.
25. Seventh day of freshman design seminar (actually 8th) discusses photodiodes and LEDs, along with feedback on the photodiode homework.
26. Lying to my students is about errors I’ve made in presenting photodiodes to the freshman design seminar.  Some of the errors were intentional simplifications, but some were just errors.
27. Ninth day of freshman design seminar (actually 10th) discusses return of two homeworks (colorimeter design and LED resistor sizing) and the first lesson on Arduino programming.
28. Tenth day of freshman design seminar (actually 11th) discussed thermal control and thermistors.
29. Twelfth day of freshman design seminar (back to correct numbering) discussed first Arduino homework.
30. Colorimeter design—almost working discussed a design I did for a cheap colorimeter, using a KL25Z board.  It is not working as well as I had expected.
31. Thirteenth day of freshman design seminar briefly discusses the drafts of the design reports and teaching programming of simple control methods for temperature control.
32. Fourteenth day of freshman design seminar discusses breaking into the design groups and answering questions from each group separately.
33. Colorimeter design—weird behavior does further discussion of the colorimeter design.  I’m now getting something that seems to be measuring the square root of what it should be measuring.
34. Fifteenth day of freshman design seminar discusses a looming TA strike, group advising, and t-shirt design.
35. Sixteenth day: Arduino demo discusses an Aruino demo that included relays, nFET control of a motor (including PWM), and using a pressure sensor to control the motor.
36. Seventeenth and Eighteenth day of freshman design seminar were mainly group meetings with help from the group tutor and me, but I discussed technical writing and the 4Cs on the 18th day.
37. Last day of freshman design seminar discusses student feedback on the course.
38. Exam day for freshman design seminar talks about the unfinished prototypes that they students showed me during the exam slot.
39. What makes teaching programming difficult? discusses the problem of teaching problem decomposition and debugging, with some ideas for how to improve it in both the freshman design seminar and the applied circuits course.
40. Designing courses to teach design—draft 3 is an updated version of my talk “Designing Courses to Teach Design”.
41. Designing courses to teach design—draft 4 is my 4th attempt at writing my talk “Designing Courses to Teach Design”.
42. Video of Designing Courses talk gives the link to a video of my Designing Courses talk.
43. Temperature-control project for freshman design seminar describes an idea for a possible project for the freshman design seminar.
44. PWM for incubator gives a bit more detail on the temperature-control project.
45. More on incubator design continues the incubator design.
46. edX finally finds the right market has a brief mention of the freshman design course, but is mainly about edX’s foray into high school courses.
47. Thermal models for power resistors presents thermal models for 3 power resistors without heatsinks.
48. Thermal models for power resistor with heatsink applies the simple thermal model to a power resistor with a heatsink, where it does not fit quite as well.
49. PWM heater and fan talks about doing PWM for a fan and for a resistor as heater.
50. PWM heater and fan continued continues the previous design work, reducing the electrical noise and making PI control loops for the fan and the heater.
51. Controlling the heater and fan talks about progress on the control loops and gives the schematic for the circuit discussed in the two previous posts.
52. Putting the heater in a box shows the physical layout of the partially completed incubator and discusses the (meager) progress today.
53. Improving feedback for fan shows the working control loops, and compares on/off, hysteresis, PI, and PI with anti-windup.
54. Thermal control loop working (sort of) shows results from using the anti-windup PI controller for temperature, as well as for fan speed.
55. Student project ideas for freshman design seminar has design project ideas for the W2015 course, as supplied by the students in the course.
56. How big is a course? talks about how many hours a course should take up, both contact hours (lecture, lab, individual meetings) and homework.
57. More on freshman design projects discusses the projects that students found most interesting.
58. Freshman design seminar writing notes discusses some of the problems I saw in the writing on the colorimeter design reports.
59. Freshman design projects moderately successful reports on the Winter 2015 course after all the projects were graded.

Below this point, I’ll be discussing the Winter 2016 offering of the freshman design course.

60. Second class of freshman design seminar discusses the first two days of class.
61. Student project ideas for freshman design seminar 2016 has the design project ideas submitted by students for Winter 2016.
62. I vs V plots for LED shows measurements I made to characterize an orange LED.
63. Smoother I vs V plots for LED shows improved measurements (from low-pass filtering the input) of the same LED, clean enough to see thermal hysteresis.
64. Phototransistor I-vs-V plots looks at current-vs-voltage plots for a phototransistor, rather than for an LED.
65. Student projects selected for Winter 2016 lists the projects students selected and some of my musings about what will be difficult on each project.
66. Ultrasonic rangefinder project shows some of my testing to see whether the ultrasonic rangefinder that one group selected.
67. More testing for ultrasonic rangefinder shows more testing, including some fairly clean echo traces.
68. OS 10.11.3 takes forever to install complains about the bloated nature of the newest Mac operating system, which I need to install to figure out why it is breaking PteroDAQ.
69. Ultrasonic rangefinders arrived reports some initial testing I did on the ultrasonic transmitters.  They have a lot of ringing, and my attempts at active suppression of the ringing were less successful than I had hoped.
70. Ultrasonic rangefinger without amplifier reports more rangefinder testing, using the resonant receiver with no amplifier.
71. Ultrasonic rangefinder with loudspeaker continues the rangefinder series, here looking at non-resonant transducers on both ends (loudspeaker to microphone), which had to be taken down to 20kHz.
72. On not using kits for a design class discusses why just buying a kit defeats the point of the freshman design course.
73. LED multiplexing gives a summary of the lecture resulting from answering a question in class from one of the LED cube design students.
74. Optical pulse monitor software discusses doing real-time software for an optical pulse monitor—most of the other discussions have talked only of the hardware with post-processing of PteroDAQ recordings.
75. Ultrasonic transmitter impedance takes a first look at the impedance of the ultrasonic transmitters—basically 1.8µF capacitors, until you get close to the resonant frequency, then very complicated.
76. Ultrasonic transmitter pulse shaping talks about ideas for ping shapes that can be cheaply deconvolved into single peaks using cross-correlation.
77. Ultrasonic transmitter impedance again refines the earlier impedance plots, using a 2.2kΩ current-sense resistor and a finer frequency sweep.
78. Oscilloscope tutorial video introduces an oscilloscope tutorial I filmed for the applied electronics class, but which is also useful for the freshman design seminar.
79. Ultrasonic rangefinder tests with tiny loudspeaker looks at using a tiny 10mm speaker instead of a resonant ultrasonic transmitter, but the results are not encouraging.
80. Redoing impedance test for tiny loudspeaker identifies a second resonance peak around 9.5kHz for the CDM-10008 10mm loudspeaker.
81. Becoming a Maker: resources for a hobbyist engineer describes some resources I’m giving for a talk to WiSE—the resources will also be useful for the freshman design seminar.
82. Ultrasonic rangefinder with Analog Discovery 2 is another in the series of posts about ultrasonic rangefinders.