# Appendix C.3 Resistance marking of The Art of Electronics, third edition: Finding resistor values

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!

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.

• 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? – jonk Jun 30 '20 at 8:11
• @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? – The Pointer Jun 30 '20 at 8:15
• I don't mind if you keep it. It might help someone else. ¿Quién sabe? – jonk Jun 30 '20 at 8:18
• @jonk muchas gracias. So what is the "multiplier" supposed to be? – The Pointer Jun 30 '20 at 8:20
• Heck. Now you may as well write your own answer! That's allowed, you know? – jonk Jun 30 '20 at 8:24

• 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.) ;) – 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.