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I have 500 resistors designed like this: five band resistor That's brown, red, black, black, brown. Roughly equal spacing between all bands. 120 ohms, right? No. This is a 10k resistor: brown, black, black, red, brown.

Why would they label it this way? They could easily have labeled it brown, yellow, SPACE, brown and it would be obvious how to read it. Am I missing some technique?

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  • \$\begingroup\$ I long ago gave up on trying to use resistor color codes to actually determine the value of a resistor (rather than to verify an already determined value). Between easily confused colours and poorly done spacing reading them reliablly is just a nightmare. \$\endgroup\$ – Peter Green Apr 8 '18 at 3:24
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According to the standard there is supposed to be a larger gap between the tolerance band and the others.

enter image description here

Now, in your particular case, that difference is almost so subtle you can not see it. However if you look closely you can see that the tolerance band has a slight gap to the neck of the resistor comparted to the first digit.

enter image description here

As such, this resistor needs to be read from the right.

However, the tolerances involved in "painting" the lines is not that well controlled, especially for cheap resistors from over-seas. As such, sometimes you have no option but to verify the resistance with an ohm-meter. If the resistors are a mixed bag of singles, that can be quite the chore. If they are still on the tape, not so much. Measure one and write the value on the tape.

If they are 5% or 10% resistors it's easier since silver and gold are not used in the first digit location.

enter image description here

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    \$\begingroup\$ Well spotted! Looks like this factory decided to make their own standard? That gap isn't the same type of gap I see described in all the online tutorials about how to read a resistor. Nevertheless, it's consistent, so with a good loupe or magnifying glass, I'll be able to read the resistors I just bought. Thanks again. \$\endgroup\$ – piojo Jan 7 '18 at 13:35
  • \$\begingroup\$ @piojo yup, it really depends on the manufacturer. 5% and 10% ones are easy since gold and silver don't show up in the first digit, 1%, 2% and 0.5% etc can be a nightmare. \$\endgroup\$ – Trevor_G Jan 7 '18 at 13:59
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4 band resistors are two digits, extra zeros, tolerance.

5 band resistors are 3 digits, extra zeros, tolerance.

So your resistor is

brown  1
black  0
black  0
red    2 x 0
brown  whatever brown means for tolerance

Mind you, it's a lot easier to work back from a known measured value and figure out what the bands mean, than to start from an unknown resistor, figure out left to right, or right to left, is that smudge an extra band, is that dark orange or light brown?

With 4 bands, knowing the E24 series by heart counts for a lot, as there's only so many values it can be.

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  • \$\begingroup\$ Thanks. But is there any way you know it's not: brown (1) red (2) black (0), black (x1), brown (precision)? Is it just because 120 ohms isn't a common value? \$\endgroup\$ – piojo Jan 7 '18 at 12:52
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    \$\begingroup\$ This answer misses the point of the question: how do you know which direction to read the bands in? \$\endgroup\$ – Pete Becker Jan 7 '18 at 13:05
  • \$\begingroup\$ @PeteBecker so you make the same observation of two other answers : what is Your solution... \$\endgroup\$ – Solar Mike Jan 7 '18 at 15:03
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    \$\begingroup\$ @SolarMike -- I don't know what the answer is. That's why I didn't write an answer. \$\endgroup\$ – Pete Becker Jan 7 '18 at 15:57
  • \$\begingroup\$ What ever happened to the superb, easy to read colors, on the Allen Bradley resistors? \$\endgroup\$ – analogsystemsrf Jan 8 '18 at 4:26
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Five band resistors, at the one end, There is more gap at last band or Last band has less width. So you've to start counting from opposite end.

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    \$\begingroup\$ You didn't look at the photo, did you? That answer is not applicable to this resistor. \$\endgroup\$ – piojo Apr 8 '18 at 3:24

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