Is there a source of information you can recommend that deals with the more escoteric aspects of component selection? I know what a transistor is and what it does but is there a recommended purpose for metalic vs carbon film type? The same with capacitors. When do you use ceramic, taladium, electrolytic? The main reason I ask is that often components mentioned in construction articles are very specific as to type. Sometimes these components are no longer available or difficult to obtain. I'd like to know when and how substitutions can be made. The answer is usually "it comes from experience". At 61 I don't have a great deal of time to accumulate much experience and am hoping there is a reference available.
The thing is, I'm 58, and still don't know the advantages/disadvantages of carbon film vs. metal film. I just buy whatever's cheaper in the catalog. :-)
Ceramic caps have moderate capacitances, can work with fairly high voltages, and have good high-frequency perrormance, but they can have high ESR, microphonics, piezoelectric effects - i.e., the capacitance can change with applied voltage. And the cheaper ones can be used as temperature sensors. ;-)
Tantalums are electrolytics made of tantalum instead of aluminum; these days, when they separate them as you did, the "electrolytic" refers to aluminum cans. The aluminum ones have the highest capacitance per unit volume, but have very wide tolerances and are polarized. Tantalums are polarized, don't have as wide a tolerance, and are smaller than an equivalent aluminum, probably better ESR and stability, but either kind can explode spectacularly if you give it too much or the wrong polarity voltage.
For small cap values, silver mica are the most temp. stable, tightest tolerance, and best HF performance, but they're expensive and don't come in very big values.
Mylar, polyester, (which are actually the same stuff), polystyrene, film, etc. work with moderate voltages, have small to moderate capacitances, and excellent to superb leakage.
Oh, yeah, aluminums are usually relatively leaky.
I'm afraid I'll have to leave transistor and inductor selection as an exercise for the student - heck, it couldn't take more than a few hours to learn how to read a data sheet, and inductors are black magic anyway! ;-)
Carbon film resistors change resistance a lot with temperature, hundreds of PPM/K. Cermets, the most common surface mount resistors, are better, 100 PPM maybe. Metal films and wirewounds are best, 50 ppm to as low as a few. If precision matters, pick accordingly. For audio, buy whatever's cheapest.
I suspect many of us did learn from experience, so other methods are not in our realm.
One thing about construction articles, sometimes they are specific because there is a real reason for a specific component, and other times they specify what they used (in effect saying, "try something else at your own risk"). They may specific because the specific is readily available, at least to them, or because they don't want all kinds of questions asking "but what kind of capacitor should I use at C1".
Though hopefully, when a specific type is necessary, it will have something like "use only polypropolene capacitors here" rather than "the .1uF capacitors are polyproplene" (the former indicating there are no options, the latter an indicator of what was used by the builder).
Not really useful, but it is background.
One thing about specific capacitors, one necessity is that the larger the value, the harder it is to get that sort of capacitance in a reasonably sized package. Hence, the move to electrolytics and tantalum (which causes and incidental move to polarized capacitors, since the makeup of such capacitors cause them to be polarized).
So small value capacitors, 20pF, might be chosen for high tolerance, because much variation from the marked value could affect circuit operation. But, that too is variable, because a coupling capacitor might not be a problem, while tuning an LC circuit it would. You might also choose a type of capacitor that isn't affected by temperature, since again a small variation might affect circuit operation.
Ad capacitance goes up, their tolerance is less important, because the circuits needing larger capacitance generally aren't fussy. The caveat being that if the capacitor is used for timing or some tuned circuit, precision is likely a factor.
So some types of capacitors are more stable with temperature, and others are available in smaller tolerances.
One way of looking at it is the more general something is, the project or the use of that capacitor, the cheaper the capacitor can be, and thus the cheaper the capacitor, the less it matters what type.
When I was a kid, you'd use electrolytic capacitors for any value over 1uF (because that's about all you could get in such high values, and if you found any non-electrolytic of that value or higher, they tended to be really large). Polarized because that's the only option electrolytic capacitors provided.
.1 and .01uF, so common as bypass capacitors, they'd be ceramic.
Smaller values tended to be ceramic or better silver mica.
You didn't fuss over brand, you bought what was available, what was cheap, or better yet scrounged what you could.
IN recent years, I've seen people fuss over specific brands, and fuss over what type capacitor to use for really general applications, which is fallout from a) a wider range of methods to manufacture capacitors and b) it's all out there in the catalogs for everyone to see. It start becoming complicated because the variety is there, rather than because that much has changed.
You look at schematics, and read the theory beside them. You start to note how common it is to bypass an emitter, you start to see the handful of basic uses of capacitors (bypass, coupling, timing or tuning), and you discard the fuss over some things, and then that leaves just a few capacitors that would ever need to be fussed over (and even then, with more thought and study, that number drops even further).
You used to be able to get books on every single type of component. I suspect you still can, but they are no longer aimed at hobbyists and thus at the very least carry a high price. But a book like that on capacitors is bound to tell you far more than you'll ever need to know on the subject.
Manufacturer's literature might be helpful, though I suspect little is being published on paper nowadays. Dig out the names of the big capacitor companies, and look for their websites, to see if they have any info there.
That was sort of a glib response, but there is truth to it.
One could spend years learning the needed stuff, and even if there were "cheat sheets" it would take time to cover enough to do whatever he presumably wants to do.
Or one could more or less jump in, learning from the experience and actually doing things now.
I've posted before about the first few electronic projects I tried to build, and they never worked. I didn't have enough skill to put them together properly (it's easy now to realize how bad my soldering was back then, but how was I supposed to know at the time?), and not enough skill or knowledge to properly figure out what wasn't working.
Yet at some point, you have to take those first steps. If I'd waited "until I'm ready", it could have been years in the future, and I'd still have to make that first attempt and it might not have worked then either.
The good thing was I didn't get discouraged. I kept reading and learning, and oddly enough, when I did get something to work, admittedly simpler things that those already simple projects, I was putting them together with parts I'd torn out of transistor radios and surplus computer boards (from a time when surplus computer boards had transistors). That first audio oscillator that did work, I bypassed the soldering, and just twisted the leads together. I can't even remember how I figured out how that scrap transistor was NPN.
The odd thing is that between those first failed projects (and they were spread months apart, since I was buying the parts new and my allowance didn't grow on trees) and getting that audio oscillator to work (and then that crystal oscillator), it was no more than a year, yet I'd picked up lots of important notions about components and what I was supposed to use.
Hence I was able to pick over parts yanked off scrap boards to make things that worked, and I was no longer so dependent on those parts lists in the hobby magazines.
The trick to any learning is that it always looks like a steep cliff when you are approaching it. But once you move along a bit, when you look back it doesn't look nearly as steep. You have to forget about how high the cliff is so you don't get discouraged.
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