I am currently studying The Art of Electronics, third edition, by Horowitz and Hill. Appendix C.3 Resistance marking says the following:

Leaded resistors are marked in one of two ways: (a) with a set of four or five color bands, indicating resistance and tolerance; or (b) with a 4-digit resistance code, followed by a letter that indicates the tolerance. Surface-mount resistors use either (a) a 3- or 4-digit resistance code, or, for the smallest package sizes, (b) no marking at all! enter image description here

I don't understand the description of C.1.: Am I supposed to be able to tell from the information given that "yellow-violet-orange-gold" is 47 \$ \text{k} \Omega \$ and "yellow-white-white-black-brown" is 499 \$ \Omega \$? I understand how the tolerances were found, but it isn't clear to me that the the information given in this section alone is sufficient to deduce these values.

I would greatly appreciate it if people would please take the time to clarify this.

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    \$\begingroup\$ I'm not sure about the difficulty. Read it backwards, if that helps. In the case of the \$499\:\Omega\$ resistor, you see "brown" as the tolerance. Looking up, you see that is 1%. Then you see "black" as the power of ten. So \$10^0\$, yes? Then you have three remaining bands, which you now read left to right as yellow (4), white (9) and white (9). So this is \$499\times 10^0\:\Omega\quad 1\%\$. Look, if you've ever read Arabic, you are good. You read right to left, unless there is a number in which case you read left to right. That's perfectly sensible, isn't it? ;) What's to confuse you? \$\endgroup\$ – jonk Jun 30 '20 at 8:11
  • \$\begingroup\$ @jonk Oh, I see! I was reading it as yellow being \$4 \times 10 \ \text{k} \Omega\$ (that is, multiplying it by the "multiplier"). Thanks for the clarification. Should I delete this? \$\endgroup\$ – The Pointer Jun 30 '20 at 8:15
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    \$\begingroup\$ I don't mind if you keep it. It might help someone else. ¿Quién sabe? \$\endgroup\$ – jonk Jun 30 '20 at 8:18
  • \$\begingroup\$ @jonk muchas gracias. So what is the "multiplier" supposed to be? \$\endgroup\$ – The Pointer Jun 30 '20 at 8:20
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    \$\begingroup\$ Heck. Now you may as well write your own answer! That's allowed, you know? \$\endgroup\$ – jonk Jun 30 '20 at 8:24

Does this make any more sense or help you understand: -

enter image description here

Taken from this Resistor clour code tutorial.

Note that the table above lazily indicates temperature coefficient as "ppm" when it should be "ppm/degC" or, parts per million per degrees celcius change.

  • \$\begingroup\$ Yes, it does. Thanks for the image. \$\endgroup\$ – The Pointer Jun 30 '20 at 8:30
  • \$\begingroup\$ Those temperature coefficients aren't bad considering copper wire is near 3300-3900 ppm/K! Not sure how I'd connect those resistors if they are low enough in value. \$\endgroup\$ – jonk Jun 30 '20 at 8:39
  • \$\begingroup\$ @jonk you should try using 2ppm/degC resistors now and then LOL. Not cheap but sometimes needed. \$\endgroup\$ – Andy aka Jun 30 '20 at 8:41
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    \$\begingroup\$ Yeah. But you know? Maybe if I connect up all my circuits using those \$0\:\Omega\$ 15 ppm/K resistors I could get better tempcos!! Cool. (I had noted the lazy designation in that picture, by the way!) I'm going to have to dead-bug up a circuit using 15 ppm/K resistors and no copper at all (somehow) or solder (somehow) and see what happens (somehow.) ;) \$\endgroup\$ – jonk Jun 30 '20 at 8:42

The problem seems to be that I was interpreting the "multiplier" incorrectly. Specifically, I was interpreting the multiplier to mean that, in the case of the yellow-white-white-black-brown resistor, we would start by taking yellow (digit 4) and multiplying it by \$ 10 \ \text{k} \Omega \$ to get \$ 4 \times 10 \ \text{k} \Omega \$, and so on for the rest.


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