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2020 July 23

Fall 2020 plans and tools

Filed under: Circuits course — gasstationwithoutpumps @ 13:44
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I swapped my Fall sabbatical for a Spring one, so that I could have time to figure out how to move my lab course into an at-home lab. I also took a university-sponsored course this summer on remote instruction to help.  That course on remote-instruction has now ended, but I still have some work to do on converting my course.  USCS will still be providing some help—they’ll be paying for a student (one of my graders from last Winter) to edit the closed captions on my videos.

I’ve made a list of some of the tools I’ll be using for the Fall:

  • I’ll be using Canvas for collecting assignments (as I have for a couple of years) and SpeedGrader or Gradescope for grading them (the badly-named SpeedGrader for written assignments, as I’ve been doing, and Gradescope for quizzes, which will no longer be on paper).
  • I have my syllabus on my own website on the University server, so that it is public (I hate secret syllabi buried inside a learning-management system—they make it nearly impossible for students to know what a course is about before they have committed to taking it). All assignments, reading schedules, … are there. Only the assignment due dates are duplicated in Canvas.
  • I use Piazza for having students ask questions, as I’ve been doing for a couple of years. It is a much better interface than the Canvas discussion forums, and students are willing to use it.
  • I’ll be using Zoom for the synchronous parts of the course—lab times and office hours. That is new for me, but I’ve been in enough Zoom meetings, classes, and webinars now to have some idea what is reasonable. I’ll undoubtedly find all sorts of new problems in the first 2 weeks of class (particularly with breakout rooms, which have not worked very well any time I’ve been in them).
  • The small stipend I got for converting my course to online required that the lectures be fully asynchronous (and that any synchronous activities be attendable even by people in a time zone 15 hours different from mine). So I’m recording mini-lectures (6 minutes to half an hour) using OBS. I’ll probably have about 35–40 of them (considerably less lecture time than the usual 32.5 hours of lecture for the course, but some of that time would normally be taken up with quizzes). I’ve set up my desktop computer at home (shared with my wife) as a recording studio, with a green screen, a document camera, and (starting today, if it arrives as scheduled) a cardioid desktop microphone.
  • I’m also planning to have video answers to the quizzes that are unlocked by submitting the quiz—those I’ll have to do at the last minute, as I usually write each quiz after seeing what students got wrong on the previous quiz. The quizzes are fairly low stakes (all 10 quizzes add up to about 13% of the grade), so I’m not going to worry that a few of the students are going to cheat like hell on them—I’ll be saddened by the cheating, but I’m not going to proctor. If I get obvious cheating (like identical very wrong answers that can’t be easily explained except by copying), I’ll still do the academic-integrity reporting and fail the students.

I’ve recorded 31 mini-lectures so far, and I’m gradually getting better at using OBS and lecturing into the void, but it is very, very different from my usual style, which involves 50′ chalkboards and is an improvisational performance in response to student questions. I’m glad that I only have to do this online stuff for one year (I’m retiring in 2021).

UCSC is  almost fully online this Fall (21 in-person courses out of 1300, mostly small lab or grad courses, so less than 0.5% of total seats).  I expect that Winter quarter will be much the same, though some optimists expect more in-person course (up to maybe 5% of total seats).

I still have to work out (with the Baskin Engineering Lab Support staff) the logistics of shipping stuff to the students. The parts that were ordered for the cancelled Spring course are available in storage at UCSC, but we’ll have to add to the list to provide some duplication for mistakes (as students can’t get same-day replacements from the BELS supply room, nor can they borrow easily from classmates), plus providing resources that were previously communal (inductors, wire, solder, soldering irons, solder suckers, safety goggles, stainless-steel electrodes, electrode holders for Ag/AgCl electrodes, …).  I’ll be making up a list soon of the changed needs for the parts kits.  We’ll also have to work out which things the students need to ship back over winter break, for distribution to BME 51A students in Winter.

We’ll probably freeze the enrollment in the class in mid-September (no late adds this year!), so that there is time for shipping.  I currently have only 32 students in the class, down considerably from the 50 who passed the first half in Winter 2020.  Some students graduated in Spring 2020 (we granted some emergency course substitutions for students whose required courses were cancelled in Spring), but I was still expecting about 40 students this Fall.

2020 July 13

Twenty-one videos for electronics book

Filed under: Circuits course — gasstationwithoutpumps @ 22:26

I’ve just published my twenty-first video for my Applied Analog Electronics book. I stopped announcing each one on the blog (the posts were getting repetitive).  You can see the entire set (in viewing order) in the Applied Analog Electronics playlist. If you want to be informed when new videos are added, subscribe to the playlist on YouTube.

I now have most of Chapters 27–32 done. I’ve got about 85 more days until classes start, so I’m pretty sure I’ll have all the BME 51B videos done, but I’m not so sure I’ll get all the BME 51A videos done.  I do have until the beginning of January for those.

I’m getting a little better about the production values: the green screen is better, I have intro music that I composed, I switch between “scenes” a bit better, and I’m a little more comfortable talking to the screen without an audience.


2020 July 10

Ring light for iMac

Filed under: Circuits course — gasstationwithoutpumps @ 08:19
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I was having some trouble using the green-screen capabilities of OBS, and the videographer who works on online courses for UCSC suggested trying a ring light behind my iMac to get more light on my face. I decided to make a ring light and see if it helped.

On Wednesday I walked to my dentist appointment, rather than bicycling, so that I could stop by Palace Arts on the way home to pick up a piece of foam core to make a frame to tape to the back of the iMac, without blocking any ventilation ports.  I already had strips of LEDs that I could use to provide the light.

Here is the layout of the ring light, seen from the front, before mounting it on the iMac.

The hinge (made by scoring the foam core and then crushing the foam slightly at the score line) allows the monitor angle to still be adjusted, even with the foam core taped to both the stand and the back of the computer.

Here is the ring light attached to the back of the iMac with blue painter’s tape and lit up.

The ring light was not difficult to make, but it did not do what we had hoped. It does illuminate my face a bit more uniformly, but the camera in the iMac automatically compensates for the extra light, resulting in the green-screen background looking olive drab and being even harder for OBS to use in chroma keying. It’s too bad that OBS doesn’t have Zoom-like background elimination, which can handle a much wider variation in color and lighting of a green screen. The ring light also does not work well with glasses, as there are two really annoying reflections of the light off the front and back surfaces of my glasses.

So I wasted a day experimenting with the ring light. My next attempt at improving the green screen will be to mount a strip of LEDs at the bottom of the cloth screen, to see if I can erase some of the shadows there and get more uniform and brighter lighting of the screen.

2020 July 3

Twelfth video for electronics book

Filed under: Circuits course — gasstationwithoutpumps @ 22:41
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I’ve just published my twelfth video for my Applied Analog Electronics book.  This video is for §34.2, which is the first part of Lab 10, and shows how to solder the FETs onto a breakout board.

I filmed the video using OBS (Open Broadcaster Software), and this is the unedited 3rd take. The first take stopped before I did any soldering, because I had forgotten to get blue tape out. The second take was complete, but had garbled sound for the intro and exit music, because I had the mic on while playing the sound, so I got a delayed superimposed sound.

I spent most of yesterday composing the 7 seconds of sound, because it has been a long time since I composed anything or used Finale Notepad. I’m not very happy with Finale Notepad, since it no longer runs on Macs (and so I had to use the “Barbie” laptop), and you can’t record the sound nor print the sheet music (it is deliberately crippled to induce you to buy the full-featured Finale). I got frustrated trying to produce the sound using online MIDI-to-MP3 converters, and ended up looking for another solution. I found MuseScore, which is freeware that runs on macs. I could import the music XML file that I had exported from Finale Notepad, and produce the sound using it—it even has a simple mixer panel that let me change the volume of the different instruments to get a slightly better balance and control the reverberation. I did have to edit the final sound with Audacity, in order to get the initial fade in. If I need to compose another short piece, I’ll try to do the whole thing in MuseScore, since it has more of what I need than Finale Notepad does.

I would upload the audio here, but only allows that if you have a paid plan, which I’ve been too cheap to do—you can hear the music on the YouTube link.

This video is the second one in this series using a green screen, and I’m still having problems with the lighting on my green screen not being uniform enough for OBS—even at night with only artificial light. The chroma key in OBS is nowhere near as easy to use as virtual backgrounds in Zoom. I have found some tricks to make adjusting the key color a little easier, but nothing that really handles the shadows and uneven lighting caused by wrinkles in the green-screen fabric.

2020 June 19

Eleventh video for electronics book

Filed under: Circuits course — gasstationwithoutpumps @ 21:01
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I’ve just published my eleventh video for my Applied Analog Electronics book.  This video is for part of §27.2, which is the first part of Lab 7, DC characterization of an electret microphone.

I filmed the video using OBS (Open Broadcaster Software), and this is the unedited seventh take. Earlier takes had problems with the order of presentation, technical problems with the green screen, technical problems with the interaction with the Analog Discovery 2, or just stumbles in saying what I intended.

This video is the first one in this series using a green screen, but I found that the lighting on my green screen is not uniform enough for OBS, particularly in a daylit room—I ended up having to do the recording at night so that I could use only artificial light. The chroma key in OBS is nowhere near as easy to use as virtual backgrounds in Zoom.  You can see some problems with the green screen even in the thumbnail shot.

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