The Art of Electronics, practically no info about thyristors & triacs - Page 1
Forum section: electronics / general

author: Karel
author_rank: Super Contributor
timestamp: September 06, 2021, 11:02:58 am
content: I just noticed that it doesn't really cover thyristors and triacs. I didn't expect that.Apart from that it's a great book.

author: Sal Ammoniac
author_rank: Super Contributor
timestamp: September 07, 2021, 05:14:05 pm
content: I thought that the second edition might, but I just checked and it doesn't either.

author: Karel
author_rank: Super Contributor
timestamp: September 07, 2021, 05:18:11 pm
content: I forgot to mention, I have the 3rd edition.

author: SiliconWizard
author_rank: Super Contributor
timestamp: September 07, 2021, 09:08:54 pm
content: The only mention of SCRs and Triacs I could find was in the "9.13.1 Overvoltage crowbars" section. (Chapter 9)There are a few examples of use, but no dedicated section as far as I could find.

author: RoGeorge
author_rank: Super Contributor
timestamp: September 07, 2021, 09:22:21 pm
content: Power electronics in a self-study book for beginners might be a bad idea.

author: Sal Ammoniac
author_rank: Super Contributor
timestamp: September 08, 2021, 08:16:23 pm
content: Who saysThe Art of Electronicsis a "self-study book for beginners"?A few years ago I did a little informal survey by walking around on the floor of my building where all of the hardware types work and noted that about 80% of them hadThe Arton their bookshelves. I wouldn't consider any of these guys beginners.

author: Rod
author_rank: Contributor
timestamp: September 08, 2021, 08:53:33 pm
content: Sal Ammoniac, that's because AoE is also a useful reference book, as well as self-study text for serious beginners.If, beside AOE3, they also have AoEX and AoE2 on their shelf, they're probably not just beginners.

author: Bassman59
author_rank: Super Contributor
timestamp: September 08, 2021, 09:19:21 pm
content: Quote from: Rod on September 08, 2021, 08:53:33 pmBy that criterion, I am not a beginner!

author: RoGeorge
author_rank: Super Contributor
timestamp: September 08, 2021, 10:14:30 pm
content: Quote from: Sal Ammoniac on September 08, 2021, 08:16:23 pmWell, I just wrote that, and with no malicious intent.Now that you asked, I had to think why did I say that. Maybe because of its clickbait style title (best title ever), and because of the fact that it's often recommended to beginners that are asking for a book to learn electronics.You made me browse the 3rd edition and TBH I don't know what it is. Looks like a combination of an electronic almanac + application notes + pocket book/cheat sheet + some exercises. Has a university as a publisher, yet it is not written in an academic language, quite contrary, has plenty of emphasis or emotion related words, fuzzy words that let many interpretations possible, even has rhetorical questions in the explanations. While the language is friendly/colorful, the book is technically correct, though the text is too brief for an absolute beginner, yet too standard for an experienced engineer.(by the way, while browsing I stumbled by serendipity over some triac/SCR usage in chapter 12.7.6 VI: Solid-state relays (triac/SCR output), page 849)IDK who was the targeted audience, or why so many of your colleagues have this book on their shelves. The book doesn't look like a reference textbook to me, it barely has any formulas in it, so I guess it must have been something else. Maybe it was a requested book in their Uni years. Engineers usually don't throw away books.Now I'm curious, too. Have you asked any of them why do they have the book?Thought, the book has already many editions now, 1k+ pages, certainly it's a lot of effort put in it, and probably it's the most famous electronics book. All these can not be just because of the beauty of its title, so I might be missing something here. (I admit I never read/study/solve any exercises from AoE, only browse it 3-4 time over the years and only out of curiosity because it was keep popping in forums or online chats as a recommendation, yet never read more than 1-2 consecutive pages from it)

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 08, 2021, 11:19:38 pm
content: In their defense, they aren't very useful/important anymore. Still quite effective for AC control, but it's largely just on-off -- get a pre-made module (SSR), follow the appnotes, whatever. Reactive loads + snubbers are a more nuanced thing.Nobody uses SCRs for inverters anymore; MOSFETs and IGBTs are so much better for all but the biggest applications (big motive power, HVDC). They're still really cool (especially if you have a flair for things operating on a knife's edge, always one misstep from slamming to a halt!*), just not very relevant these days.*A typical SCR inverter commutates (transitions from one state to the other) by literally shorting out the supply; a resonant network supplies reverse current a brief moment later, forcing reverse recovery of both devices. Then, the device still being driven, turns on and conduction resumes. If the commutation fails for whatever reason (e.g. load current > peak commutation current, so the previously-active device never actually gets turned off), well, it's just stuck there, and the power supply starts growling, until a fuse pops, or something worse happens.Another interesting property is, SCRs are the only intrinsic current-sourcing switching device. What I mean by that is, if you have a capacitive load, driven by a current source, you can use SCRs to switch it back and forth, and the load provides the commutation current naturally -- no need for a reset network. The supply must be a current source (typically an extremely large inductor, which might in turn be supplied by an SCR phase controller from the AC line), and the device waveforms (voltage and current) are exactly swapped from those of a constant-voltage inverter (whereas MOSFETs conduct current in reverse, SCRs drop voltage in reverse -- the V-I transformation is very mind-bending when you first see it but this is how it works).I'll note there are IGBTs that allow reverse voltage (Vce << 0), but they're kind of specialty and I'm not sure how relevant, overall, they are. (Most only admit -5V or so, essentially E-B breakdown of the BJT; co-pack devices are common, i.e. an antiparallel diode so they're convenient to use exactly the same way as MOSFETs.)Tim

author: NiHaoMike
author_rank: Super Contributor
timestamp: September 09, 2021, 03:24:44 am
content: Quote from: T3sl4co1l on September 08, 2021, 11:19:38 pmIGBTs and MOSFETs are also on/off, they're just able to switch between the two much faster than SCRs can.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 09, 2021, 03:49:04 am
content: Uh, IGBTs and MOSFETs are linearly controllable?Tim

author: james_s
author_rank: Super Contributor
timestamp: September 09, 2021, 04:09:23 am
content: One of the most common modern applications I can think of for thyristors is in triac based light dimmers and motor speed controllers but even those are starting to go away. Most of the dimmers I have now are mosfet based trailing edge dimmers which tend to work a lot better with LED bulbs. I can see why there wouldn't be a whole chapter on them but it does seem like the book ought to have a few pages covering them.

author: Sal Ammoniac
author_rank: Super Contributor
timestamp: September 10, 2021, 06:15:39 pm
content: Quote from: RoGeorge on September 08, 2021, 10:14:30 pmNo, I didn't, but that's something I'll do out of curiosity. It'll have to wait until we're back in the office when the pandemic is over.

author: KE5FX
author_rank: Super Contributor
timestamp: September 10, 2021, 08:00:59 pm
content: If you ask an analog person, they will probably say that AoE is handy when they need to work in an area where they don't have a lot of existing experience (or colleagues to bug) and need to come up to speed quickly. Maybe they need to do something with discrete transistors for the first time since they left school, for instance. AoE is almost certainly all they'll need.Also, if they don't know much about low noise work but find themselves needing to worry about it, AoE3 is an excellent starting point, and again it's comprehensive enough that it might be all they need.If a programmer opens the book, they must save versus electrical attack or lose 2d6 x 1000 experience points.

author: james_s
author_rank: Super Contributor
timestamp: September 10, 2021, 10:40:48 pm
content: Several years ago I interviewed at a place where they mentioned they were having trouble finding qualified people out of the recent college grads, they did a fair amount of analog and discrete work and they said the recent grads all wanted to work with microcontrollers and digital and seemed to have forgotten everything they had learned about transistors, op-amps and other fundamentals. I preemptively turned down the job after thinking about the commute and other factors but I was surprised when they sounded disappointed and even mentioned I was easily the most qualified applicant they had interviewed, and I dropped out of college just a couple years in.