It's not easy being a beginner........ - Page 1
Forum section: electronics / beginners

author: Noidzoid
author_rank: Regular Contributor
timestamp: October 14, 2019, 07:32:40 pm
content: I was reading Electronics for Dummies last night and thought I would have a browse in the glossary. Now I was willing to accept everything I read as correct and to soak up the lingo (as I know next to nothing about this subject at the moment), UNTIL I read the following which I KNOW to be false.I find this concerning! When trying to learn the technicalities of a new subject being mislead in such a way can make you believe that you'll never get the hang of something and give up when for instance a formula you learned off by heart was incorrect thus never allowing you to achieve the correct answer.In this instance, imagine telling an engineering student that a hexagon was "squarish". Ok, so now a hexagon has what? Four sides, four corners. I could maybe understand, but only just, if the shape being described was a parallelogram or a rhombus.Up to this point if the book had stated that a transistor was batteryish I would have read on without knowledge of the nonsense I had been served, until I had learned better later on and maybe wasted valuable time.What else am I expected to cross reference before I can know that the information I am reading is correct?OK. Thanks. Rant over....

author: TheHolyHorse
author_rank: Regular Contributor
timestamp: October 14, 2019, 07:51:38 pm
content: One way to make sure it's not just jibbirish is to do some research on what books to read. There are plenty of books that thousands have read, one of those books are less likely to contain false information. Personally I've never read an electronics book, I prefer just reading up some things on le internet and just wing it and see what happens. Failure is the best way to learn

author: Gyro
author_rank: Super Contributor
timestamp: October 14, 2019, 07:54:47 pm
content: Well at least it hassomecorners, just a couple too many. It's when they become circular that you really need to worry!I understand your concern though - Electronics for Dummies isn't the most authoritative reference (any more than the rest of the Dummies series). It is a relatively accessible basic taster though. As you learn and want to explore specific areas in more detail then you will certainly want to cross reference information. Luckily the internet makes that very easy these days.No, it isn't easy starting from scratch.

author: Noidzoid
author_rank: Regular Contributor
timestamp: October 14, 2019, 08:03:56 pm
content: Quote from: TheHolyHorse on October 14, 2019, 07:51:38 pmThat is what I do mostly these days. It's also how I thankfully ended up here, but I saw this book used and for £2.99 I thought it worth a go. To be fair, as an introduction to the subject it probably isn't that bad, I was just a shocked when I read the line in question.

author: Noidzoid
author_rank: Regular Contributor
timestamp: October 14, 2019, 08:09:35 pm
content: Quote from: Gyro on October 14, 2019, 07:54:47 pmHa! Like it. I was going to use the analogy of sine & square waves but remembered reading something about the way some generators base one on the other which is not a good thing (or is it) and thought I didn't need to make a real dummy of myself, not understanding fully at the time anyway. :-)

author: konzill
author_rank: Newbie
timestamp: October 14, 2019, 08:29:10 pm
content: I decided to go with The Art of Electronics for my main book. Turns out it goes through things at breakneck speed and does not always do a great job of explaining them.As an example its explanation of Thévenin's Theorem left me completely confused. I guess its really meant to be used in a University setting where you are also attending lectures.

author: Rigolon
author_rank: Regular Contributor
timestamp: October 14, 2019, 08:30:50 pm
content: Well... English is not my first language and definitely not the language I learned electronics.But in electronics many terms are used in english no matter the language you are learning in.That being said, I don't think that's the part you should concern. It's Electronics for Dummies and not a book to be used as reference book in a university. Plus hex(allen) it's more linked to mechanics or geometry, if that's the case, instead to electronics. And I think it's easy to understand what they want to say with "squarish". So IMHO it shouldn't be something to fuzz about. Sure, they could just said hexagon instead of squarish, since hexagon is a pretty common thing.What I would worry more it's about the High Signal. Again, as I did not learn in english, whenever we were talking about high signal, we are talking about the logic state. Specially in digital electronics. And in that case, not all signal higher than 0V is a high signal. In CMOS components, for example, high signal is between 3.3 to 5V (Vcc = 5V). Between 0 and 1.5V it's a low signal. Yet again, this interpretation could be because of the languages differences.

author: andy3055
author_rank: Super Contributor
timestamp: October 14, 2019, 09:03:54 pm
content: I think it is time to put that book aside. If the author does not know the difference of the hex head and a square head, the more advanced stuff in it may be highly questionable. Or may be he knows his Electronics theory but has a poor knowledge of Mechanical engineering. I started as an electrical engineering apprentice at 21. But at home I had been tinkering with stuff since about 10 or 12. I remember dismantling dry batteries from the old radio to see what they looked like (yes, it is old stuff). The apprenticeship included going through all workshops even though it was Electrical. I did Machine shop, Foundry, Boiler, Pattern shop, Drawing office, etc, etc, before I did my last full year out of four in the Electrical shop. What I know in Electronics is all self taught. That makes me very cautious.Ultimately, I am aware that there are thousands of times more things that I can still learn at 68! Knowledge is something we humans keep acquiring until the day we depart.Just my 2 cents.

author: Leiothrix
author_rank: Regular Contributor
timestamp: October 14, 2019, 09:16:20 pm
content: Eh, it's just humor, I don't get the outrage.The "for dummies" books are written very informally, I'd imagine there are plenty of similar things in there.

author: rstofer
author_rank: Super Contributor
timestamp: October 14, 2019, 09:53:02 pm
content: Try this book "Getting Started In Electronics" by Forrest Mims:https://www.amazon.com/gp/product/0945053282/ref=dbs_a_def_rwt_bibl_vppi_i0You'll get nowhere unless you do some experiments. It's easy to read and forget; if you want to remember, do an experiment.Grab a battery, some resistors and a DMM. Verify Ohm's Law! Sure, it's boring, but it is vitally important to know how voltage dividers work. And everything else we do with Ohm's Law without even thinking about it. Have the three forms down cold! Then add in the power equations. If your resistors self-destruct, you'll have some idea why. P = E2/R or I2*R or I * E so power goes up quickly with either voltage or current. But of course, voltage and current are tied together with Ohm's Law.Get this stuff down pat and you have a leg up when it comes to circuits. We spent a LOT of time on Ohm's Law in EE school.One problem with Mim's book is that he starts out using electron flow (page 20) while the rest of us are using conventional current flow where the current flows from plus to minus while the electrons (about which we seldom care) flow from minus to plus. I didn't look to see if he changes that when he gets to circuits. Just something to be aware of.

author: vk6zgo
author_rank: Super Contributor
timestamp: October 15, 2019, 04:18:39 am
content: Quote from: Noidzoid on October 14, 2019, 07:32:40 pmYeah!Good to see your BS meter is working well!The glossary statement was "double dumb"!"Hex" in the electronics sense, is more likely to refer to "Hexadecimal"or sometimes just "six"as in things like "Hex Inverters"(I aways felt the latter device sounds more like something you would need for self defence if you upset a Witch!)The bit about "high" digital voltage levels is BS, too---- the range of voltages which are read as "ones" or "zeroes" are different for the various types of technogy used to manufacture digital ICs, & normally are included in the device "spec sheet", but a "high" is never just "any value above zero"!Edit:- Oops! In my eagerness to get to my "witch" joke, Ialso misled you.I have added the part in italics to clarify things!

author: vk6zgo
author_rank: Super Contributor
timestamp: October 15, 2019, 04:34:25 am
content: Quote from: Rigolon on October 14, 2019, 08:30:50 pmIt's not a "language thing"-- see my posting!On another issue, people have said, in effect, "Well, it's for Dummies, you can't expect much".I have, in passing, read a few "for Dummies" books, & they are mostly better than that.That said, I remember using recommended Maths books, where the "Answers"section at the rear were full of errors.(& that was in the "golden era" of textbooks).If the errors in his book freaked the OP out, imagine what it would be like for High School kids where "the book" was virtually "the Word of God"!

author: Noidzoid
author_rank: Regular Contributor
timestamp: October 15, 2019, 05:40:41 pm
content: Quote from: Leiothrix on October 14, 2019, 09:16:20 pmMy bad obviously. I did buy a book "for dummies" so why would I expect it to be factual. If you explain anything to a real dummy it probably wont be understood or appreciated anyway, so why bother making it true if you can amuse yourself at the dummies expense?I suppose the "humour" of putting a joke book in the educational books section was part of the joke.I know, not getting it proves my dummieness.Oh well, live and learn eh? I try to anyway.

author: RoGeorge
author_rank: Super Contributor
timestamp: October 15, 2019, 06:10:14 pm
content: When it's online info, chances are the material has no peer review, so less trustful.When it's paper printed, almost sure the material was peer reviewed, so chances are the book is correct, even when it defies common sense.That's a good reason to search if there are Allen keys with different head profiles. Turned out square Allen keys exist:https://duckduckgo.com/?q=square+allen+key&iax=images&ia=images

author: Gyro
author_rank: Super Contributor
timestamp: October 15, 2019, 06:19:54 pm
content: Quote from: Noidzoid on October 15, 2019, 05:40:41 pmStick with it. The start of the learning curve is always the steepest. As you gain traction and start prototyping simple stuff then things will flow much better... until you accidentally stray into something more specialist like high frequency RF, then you realize that you know bugger all again.This forum is an excellent way of cross checking things. As long as it's clear that you've put in a bit of legwork first, you will find a vast amount of collective engineering experience at your disposal. Don't forget forum search too, it's likely that most basic questions will have been covered at least once before.

author: Noidzoid
author_rank: Regular Contributor
timestamp: October 15, 2019, 08:18:44 pm
content: Quote from: RoGeorge on October 15, 2019, 06:10:14 pmThe definition was primarily of "Hex" followed by "(also called Allen)". So I'm sorry but as much as I appreciate your reasoning I cannot agree with you. In this case, Hex was used, as was Allen therefore I don't think it unreasonable to assume the item in question is a Hexagonal Allen. (Did I learn my shapes wrong in primary school?)I am well aware of most of the different shapes that have been forged or machined onto the ends of allentypekeys , including mass produced and ones I have had to make myself for specialist applications.I believe the name "Allen" being taken from the Allen Manufacturing Company (bought out with various setups since) who registered it as a trademark. The correct name for the tool made by any other manufacturer isHex/HexagonalKey, but in the same way that we call vacuum cleaners hoovers, the same applies in this situation.A square allen key is therefore not technically an allen for two reasons, just a plain old square drive key, and not even that would be called "squarish" (with the possible exception maybe a one off having to be made for a special situation).I am more than happy to be educated if any of what I have just written is incorrect but submit this post as being correct to the best of my knowledge.Never too late to learn new things, which is also what I am trying to do here and elsewhere with electronics.

author: Noidzoid
author_rank: Regular Contributor
timestamp: October 15, 2019, 08:45:13 pm
content: Quote from: vk6zgo on October 15, 2019, 04:18:39 amHa! Love Hex inverters, I always take one when walking in the woods late at night!But seriously, you have just illustrated my point and highlighted my concerns, as I would in fact have read the next entry in the glossary without knowing it was wrong.

author: Noidzoid
author_rank: Regular Contributor
timestamp: October 15, 2019, 08:53:20 pm
content: Quote from: rstofer on October 14, 2019, 09:53:02 pmThanks for this, I will be sourcing this book asap.

author: StillTrying
author_rank: Super Contributor
timestamp: October 15, 2019, 09:28:47 pm
content: It's a good idea to learn how to do images as well.10 kB version instead of 2 MB and 4160 pixels.

author: Noidzoid
author_rank: Regular Contributor
timestamp: October 15, 2019, 09:38:15 pm
content: Quote from: StillTrying on October 15, 2019, 09:28:47 pmI see. Thank you kindly

author: StillTrying
author_rank: Super Contributor
timestamp: October 16, 2019, 11:55:30 am
content: That's a much better usable viewable image in the 1st post.I loaded the 2M 4160pix image.Adjusted the brightness a bit, and the contrast a bit more.Resized it to 700pix wide, which easily fits a browser's width without any resizing, and looked fine at 100%.There's only about 230 unique colours in it, so reduced the colour to 8-bit grey scale.Saved it at normal .jpg compression, which gave the only 10kB.

author: krish2487
author_rank: Frequent Contributor
timestamp: October 16, 2019, 12:33:04 pm
content: Bingo!!! I was wondering when someone would notice the "absolute" statement about digital high!!!!:-)Quote from: vk6zgo onYesterdayat 04:18:39 am

author: StillTrying
author_rank: Super Contributor
timestamp: October 16, 2019, 12:45:45 pm
content: krish2487Ifyou want to fix your quotes untick "Show WYSIWYG editor on post page by default."https://www.eevblog.com/forum/profile/?area=theme;u=11495

author: krish2487
author_rank: Frequent Contributor
timestamp: October 17, 2019, 05:14:03 am
content: Thanks @stilltrying.. I just changed the settings.. Lets see how that works out...Edit: It Works!!! Thank you!! It was driving me crazy..Quote from: StillTrying on October 16, 2019, 12:45:45 pm

author: tautech
author_rank: Super Contributor
timestamp: October 17, 2019, 08:58:12 am
content: Quote from: RoGeorge on October 15, 2019, 06:10:14 pmAnd they're called Robertson drives.https://en.wikipedia.org/wiki/P._L._Robertson

author: Noidzoid
author_rank: Regular Contributor
timestamp: October 17, 2019, 11:41:41 am
content: Quote from: tautech on October 17, 2019, 08:58:12 amThat is genuinely interesting, thanks(I am adding this bit in brackets to assure you this is not sarcasm as it is easy to be misunderstood in situations like this.)So a square drive key is called a Robertson and was manufactured by the same as although Allen may have previously come up with the idea, could not make it feasible to produce.So:Square drive key = RobertsonHex drive key = AllenCorrect?

author: tautech
author_rank: Super Contributor
timestamp: October 17, 2019, 06:43:30 pm
content: Quote from: Noidzoid on October 17, 2019, 11:41:41 amYep correct, yet if you speak of Hex or Square drive everyone instantly knows what you're talking about.

author: Noidzoid
author_rank: Regular Contributor
timestamp: October 17, 2019, 06:54:57 pm
content: Quote from: tautech on October 17, 2019, 06:43:30 pmMy thoughts exactly. Which is what frustrated me in the first place when reading Hex, Allen and squarish in the same definition.I don't know much about electronics but if you saw a wave on a scope that was supposed to be a square wave, would it be ok if the corners were wobbly? Would it be ok if they were squarish? Or would it mean something was not right and need addressing?

author: tautech
author_rank: Super Contributor
timestamp: October 17, 2019, 06:58:56 pm
content: For your enlightenmentandentertainmenthttps://www.eevblog.com/forum/testgear/show-us-your-square-wave/

author: Noidzoid
author_rank: Regular Contributor
timestamp: October 17, 2019, 08:01:37 pm
content: Quote from: tautech on October 17, 2019, 06:58:56 pmAha! I see lots of squarish waves.I will continue reading though I think it will be a while before I understand it all.Thanks

author: rstofer
author_rank: Super Contributor
timestamp: October 17, 2019, 09:23:47 pm
content: This particular subject, square waves into a bandwidth limited scope, is going to take a while to truly understand. The math of the Fourier Series is a bit tedious and not at all important at this point.The short version: A square wave is composed of a series of sine waves at odd harmonics (1st (fundamental), 3rd, 5th...) from DC to daylight (a really high frequency). The amplitude of each sine wave is related to 1/n where n is the harmonic number. As a result, by the time we get to the 9th harmonic, we're talking about a relatively small but nonzero contribution.So, take a 100 MHz square wave and put it through a 100 MHz scope. All you will see is a 100 MHz sine wave because the next harmonic is the 3rd (300 MHz) and that will never make it through the analog front end of the scope. You absolutely won't have any 5th harmonic. So all you see is the 1st harmonic, a sine wave at 100 MHz.Repeat the experiment with a 10 MHz square wave and it will look pretty good because the 9th harmonic will pass through the front end.Attached is the output from the Analog Discovery Spectrum tool. It shows the spectrum of a 2V p-p square wave of 1 kHz that is symmetric with 0V (+1 to -1). As a result, there is no spike at 0 Hz (the DC offset that would be present if the signal was 0V to 2V) and it shows the contributions out to the 19th harmonic and the amplitude is still not 0.This is a five minute experiment with the Analog Discovery 2 which is why I think so highly of it.At this point it is sufficient to know that you can't see a 100 MHz square wave on a 100 MHz scope.

author: Paul Moir
author_rank: Frequent Contributor
timestamp: October 18, 2019, 03:10:17 am
content: Quote from: tautech on October 17, 2019, 08:58:12 amBeing a bit pedantic here, but a square drive is not a Robertson. A Roberson is atrapazoidtruncated pyramid, which is what makes it awesome, while square drive and Allen are not and therefore not awesome. Think lathe key. (For Noidzoid's sake: Canadians are a little patriotic about our screw. While the rest of the world foolishly ignores them, you'll find them ubiquitous here.)

author: Dave
author_rank: Super Contributor
timestamp: October 18, 2019, 06:00:39 am
content: Quote from: konzill on October 14, 2019, 08:29:10 pmThe vast majority of The Art of Electronics is layman level stuff. It's a 1200 page book, there is only so much they can pack into it.

author: Noidzoid
author_rank: Regular Contributor
timestamp: October 18, 2019, 08:06:43 am
content: Quote from: Paul Moir on October 18, 2019, 03:10:17 amI do believe they are used in some differential plugs. Excellent as the key doesn't jam in the hole. Name not known to me as Robertson (unit now) but well aware the use. And yes, lathe keys rarely get stuck unless something fouls it. Nothing wrong with your well placed pride for your countryman it is an excellent design.

author: StillTrying
author_rank: Super Contributor
timestamp: October 18, 2019, 10:21:24 am
content: Quote from: Dave on October 18, 2019, 06:00:39 amI think you could get quite far just knowing all of AoE's subjects in layman's terms.QuoteIs it just me that can think of at least 3 solutions to theonly 1200 pagesproblem.

author: NivagSwerdna
author_rank: Super Contributor
timestamp: October 18, 2019, 10:46:08 am
content: TBH I was more concerned with the definition of High Signal. I think you need another book. Art of Electronics can be had cheap second hand every now and again.

author: rstofer
author_rank: Super Contributor
timestamp: October 18, 2019, 06:12:31 pm
content: Quote from: NivagSwerdna on October 18, 2019, 10:46:08 amThere was a time when logic levels were compatible with vacuum tubes and even analog computers had swings from -100V to 100V and that was just their linear region, the supply voltages were much larger - perhaps +-300V.We went through a long period where 5V TTL was king and although the switching threshold was much lower (logic 0 < 0.8V, logic 1 > 2.0V, we just called it 5V logic. But since the output voltage could be as low as 2.4V, there wasn't all that much margin between 2.4V minimum output and 2.0V minimum required input.Tocay 3.3V is common, 1.8V is coming along. Lower voltages are in process.https://www.analog.com/media/en/training-seminars/tutorials/MT-098.pdfSo, the definition in the text is sloppy because a logic one is not just a small delta V above 0V because the logic 0 threshold has to be some value > 0V but it's getting to the point where the thresholds are quite low and quite close together. How far can you divide 1.5V? Maybe a logic 0 threshold of 0.5V and a logic 1 threshold of 1.0V or something like that. Pretty darn close to 0V for the logic 1 threshold.The book is sloppy and everything should be taken with a grain of salt (or more).If you wonder why logic voltages are getting lower, it is because of switching speeds. There is an equation that goes like i = C dv/dt -- the instantaneous current is equal to the capacitance of the circuit times the time rate of change of voltage (how long does it take to change voltage level). We want dt to be small because we want to switch in near-zero time for speed. We have only minimal control over C but smaller device geometry helps reduce it so the only thing we can do to reduce current (and heating) is to restrict dv, the swing in logic voltages. We have to reduce the heat because we have so many gates changing state on a particular clock edge and we do that with smaller geometry (to reduce C) and lower voltage swings (to reduce dv) and this allows us to kick dt even lower (logic is faster) and speed is good!