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I'm not an expert in this matter, so AFAIK the most part of electronic components have numeric values while resistors and few other components have colors: why is that? Why there is not a standard for all electronic components establishing the use of values everywhere? I know there are a bunch of very interesting opinions out there (for example Why do resistors still use color coding?), so I'm not looking for one more "opinion" based on personal intuition or needs, but for something more, a kind of "Official" answer.

Would not it be better to have a unique standard method for indicating values of any kind of components expressing them the same way (using just numbers everywhere or just colors everywhere)?

I'm thinking to people that is color blind: isn't better to have just values indicated by numbers and letters to make them able once for all to not confuse a color with another? IMHO this would be in general a better way to go.

PS: If some one votes down please specify why exactly, thanks in advance.

willy wonka
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    The coloured resistors are smaller have been around a lot longer than the newer numeric labelled parts. Back then, it was difficult to print numbers on such small components. Why is it still used? Because it was used before =/. – DKNguyen Feb 27 '19 at 23:08
  • @Toor: so it is just for "tradition"? – willy wonka Feb 27 '19 at 23:10
  • I wouldn't say tradition because that extols it too much. Just more of an insufficient incentive to change (with various types of inertia like tooling, educational, business risk, etc.). It's like why we still use keyboards with staggered rows even though we don't need the typewriter arms to reach out from underneath each key to the back of the typewriter anymore. Square grid keyboards are easier to learn on, more ergonomic, and make for compact keyboards but there aren't many of those around. People just don't care enough. – DKNguyen Feb 27 '19 at 23:12
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    In SMD, resistors have numbers and capacitors have no markings at all! – Dave Tweed Feb 27 '19 at 23:34
  • You can read an axial-lead resistor with color bands from any angle. There are (and have always been) some axial-lead resistors with numbers (usually precision units), and they're a pain to read in-circuit unless the person doing the assembly was careful about orientation. – Dave Tweed Feb 27 '19 at 23:45
  • `All electronic components have numerical values`... except perhaps... components that are not surface mounted? What about inductor coils? Surface amount resistors and capacitors that are really really small? etc. –  Feb 28 '19 at 00:05
  • downvote .... this is asking for an opinion and invites endless discussion .... `Would not it be better to have a unique standard method for indicating values of any kind of components expressing them the same way (using just numbers everywhere or just colors everywhere)?` – jsotola Feb 28 '19 at 00:11
  • @DaveTweed, it would be better (and maybe enough) to add into books that teach electronics and soldering techniques to be careful about orientation to grant readability to the circuit boards after populated by electronic components. This could become a standard too, as mounting a transistor the right way without inverting pins... Being careful is just part of the job. – willy wonka Feb 28 '19 at 01:05
  • @KingDuken You are right, but in such situations even colors can be hard to read correctly IMHO – willy wonka Feb 28 '19 at 01:06
  • Likewise, not all of us aren't colourblind, yet here colour codes are. You can talk about all the side effects of staggered keys just like you can talk about the benefits of colour coded resistors. It doesn't change the fact they were originally made a certain way for a reason that's not as applicable anymore, even if there were beneficial side effects, and continues to be made that due to inertia rather than said beneficial side-effects. – DKNguyen Feb 28 '19 at 01:08
  • @jsotola I said "kind of Official answer". – willy wonka Feb 28 '19 at 01:08
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    The conversation about keyboard layouts is completely irrelevant to the question. Take it to chat. – Dave Tweed Feb 28 '19 at 01:17
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    @willywonka There used to be cases where for example orientation was CBE and BCE so some things were not standard to teach in textbooks. EXPERIENCE comes from reading datasheets. While colour codes were standardized 100 yrs ago then enhanced with higher significant figures for resistors . Semiconductors on the other hand use simple unique OEM codes which due to small size is used for SMD CODES which you can find – Tony Stewart EE75 Feb 28 '19 at 01:44
  • @jsotola, not really: in fact I've found what I was looking for, but thanks anyway – willy wonka Feb 28 '19 at 01:45
  • eg https://electronics.stackexchange.com/questions/334128/how-do-i-identify-smd-components-or-how-do-i-identify-any-component – Tony Stewart EE75 Feb 28 '19 at 01:48
  • Since leaded resistors are ROUND axial, numbers cannot be used but for SMD resistors they are and since part numbers have too many numbers & letters , they cannot use colours. Everything is done for a reason. So if it is round and axial, colour bands make sense and are used in small axial Inductors and caps – Tony Stewart EE75 Feb 28 '19 at 01:50
  • however modern laser printing allows text and for very high volume, with resistors at $0.001, each printing is often excluded to save cost for automation in controlled material flow – Tony Stewart EE75 Feb 28 '19 at 01:57
  • Then there are cases where part numbers applied to a customer spec and thus what is etched or laser printer on an IC is the customer part # not a commercial #. So there are many rules about part number that are "standard" and "some" unique to that industry or supplier. The rules are rarely discussed in textbooks and only comes after experience in industry – Tony Stewart EE75 Feb 28 '19 at 01:58

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According to Wikipedia,

Color bands were used because they were easily and cheaply printed on tiny components.

Resistors are not the only part, for which color-code is used. It is also used for some ceramic capacitors.

IMHO it is much easier to indicate the value of a cylindrical resistor on PCB when it is colored, than with the value written on it, since it does not have the top or bottom side.

For SMT parts people use printed value because SMT part has defined the top and the bottom side, so the text is always visible.

SamGibson
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litvinik
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  • Maybe here you can get "official" version https://en.wikipedia.org/wiki/Electronic_color_code#Resistor_color-coding – litvinik Feb 27 '19 at 23:11
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    You should post that link in your answer, for a more 'complete' answer. ALWAYS highlight quoted material and ALWAYS list the link(s) that you used. –  Feb 27 '19 at 23:29
  • This is what I was looking for, thanks. I just want to add some more infos from the same source you cited (Wikipedia): "However, there were drawbacks, especially for color blind people. Overheating of a component or dirt accumulation may make it impossible to distinguish brown from red or orange. Advances in printing technology have now made printed numbers more practical on small components." – willy wonka Feb 28 '19 at 01:43
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    @willywonka I could be mistaken but I believe the letter code is now burned in with a laser, much like the letters and symbols on your keyboard. Color codes are done with 2-part epoxy, which is immune to most solvents. –  Feb 28 '19 at 02:10
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You are wrong, there are some film or ceramic capacitors whose value is color-coded, as well as some inductors.

Moreover, SMD resistors have digit-coded values.

user2233709
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