Recently, I’ve been penning a series of articles on the topic of switch bounce (see Switch Types, Switch Terminology, and the Ultimate Guide to Switch Debounce Part 1, Part 2, and Part 3). From the outset, my chum Peter Traneus Anderson (a.k.a. Traneus Rex) warned me that this was a deep rabbit hole into which one might fall, and that it might prove difficult to dig my way out again. Peter is a wise man, is all I can say.
Ah, how I remember the tricks they taught us at Engineer’s Finishing School (Click image to see a larger version — Image source: Max Maxfield)
More recently, I was chatting to my friend, Aubrey Kagan, who started off in Rhodesia (now Zimbabwe), bounced around the world, and ended up settling in Canada. Aubrey reminds me of another friend, David Ashton, who also started off in Rhodesia, ricocheted around the world, and eventually planted himself in Australia. I believe it to be mere coincidence that Aubrey and David managed to end up just about as far from each other as it’s possible to be. The reason I say Aubrey reminds me of David is that either of them could out-engineer your humble narrator without breaking a sweat. Both members of this dynamic duo have spent their careers designing, debugging, and fault-finding electronic systems in weird and wonderful environments, ranging from the bottom of mines to the top of radio towers. I remember several years ago when I built a Geiger counter that didn’t count. One problem was that I didn’t have a radioactive source with which to test this little beauty, so I didn’t know if the fact that it was silent indicated a lack of radiation or a failure of the system. I wrote a blog about this, following which David emailed me to tell me to send it to Australia for him to look at, so I ambled down to the post office to dispatch the little scamp on its way. When I returned to my office, I found a gift from another reader sitting on my desk — a package of radioactive marbles. So, I started the day with a Geiger counter but no radioactive source, and I ended it with multiple radioactive sources but no Geiger counter. I’ve said it before and I’ll say it again, it’s a funny old world, and no mistake, but we digress… As part of my conversation with Aubrey, the topic of switch bounce reared its ugly head. I think I mentioned that — to the best of my recollection — this subject was not one I was taught at university. This prompted Aubrey to note he was of the opinion that there should be a “Finishing School” for electrical and electronic engineers in which they were taught a suite of real-world nitty-gritty skills. Oh dear. I didn’t mean to do that. I’m sure that, like me, as soon as you read the preceding sentence you immediately started thinking of The Nitty Gritty by Shirley Ellis.  
I was going to say that you don’t see much dancing like that these days, but then I thought of my friend Little Steve and his interesting interpretations on the dance floor, which made me decide to hold my tongue. Anyway, Aubrey suggested a few topics he felt should be included as follows:
  • Switch bounce
  • Driving transistors (bipolar and FET)
  • Interfacing to different (industrial) voltages
  • Relays (driving the coil, bounce and turn on/off times, back EMF)
  • Driving SCRs and Triacs
  • The wiles of isolation and ground loops
Of course, this is a slippery slope, because we could easily create a catalog containing so many topics as to form a complete university degree course in their own right; however, if we assume we’re talking about something a little less imposing, like a 6-week summer finishing school, for example, then what items would you add to the list?