Gas station without pumps

2018 January 17

Long weekend, little done

Filed under: Circuits course — gasstationwithoutpumps @ 10:01
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Last weekend was a long weekend (Martin Luther King Day on Monday), and I briefly had fantasies of getting a lot of stuff done.  The trouble is I never settled on exactly what it was I would get done, so I ended up doing very little.  I read science fiction, I slept a lot, I tinkered with my book a little bit, I got the live Christmas tree out of the house, and I adjusted the brakes on my bike. but that’s about it.

The main addition to the book wasn’t even a very important one—this picture:

Some of the most common packages for FETs.

We used to use TO-220 and TO-251 packages for the class, since that is how power FETS are most commonly packaged, but the power FETs are getting expensive (the cheapest ones keep getting discontinued—maybe they were cheap because they were end-of-life, or maybe they were discontinued because there wasn’t enough profit at the low price point).  We had problems last year with TO-251 packages not staying in the breadboards—the springs seemed to pop the leads out rather than grabbing them.

This year we’ll be using the SOT-23 transistors, which are much cheaper, and soldering them to a breakout board.  I’m a little worried about how many of the students will have trouble with hand-soldering the small parts.  They’ll have had a little more practice soldering by then, so I’m hopeful that it will go ok.

The other changes to the book were mostly typo fixes for problems found by my students.  The students have been very good this year at reporting problems to me, and there were a lot more typos than I expected (averaging about 1 every 3 pages).  So far they’ve not pointed out any substantive errors, though there was one omission that I’ve fixed—it seems that some students have not heard of raster image formats, and thought I was trying to say “faster image formats”, so I’ve added a couple of paragraphs about image formats.  The changes that I’m making this quarter will be in the next release, which will probably be in March, during spring break.

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