I'm having a difficult time identifying a resistor's value as I can't find the golden / silver tolerance line.

The problem is that I can't see a silver or gold line here! They're both brown on both sides
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  • $\begingroup$ There is very little usage of 5% and 10% carbon resistors now, compared with 1% or 2% metal film resistors with 5-band coding as in your images. Unless a you really want the specific properties of carbon resistors (e.g. higher temperature coefficient than metal film), why pay more money for lower specification parts? $\endgroup$
    – alephzero
    Aug 7 '16 at 20:48

Based upon the pictures, it appears that the bands are:

Brown, red, black, black, brown.

Using one of many readily available color code charts or calculators that are online, it appears that you have a 120 ohm resistor with 1 % tolerance.

1st band, 1st digit - brown - 1
2nd band, 2nd digit - red - 2
3rd band, 3rd digit - black - 0
4th band, multiplier - black - 1
5th band, tolerance - brown - 1%.

Notice the additional gap between the last black band and the second brown band. That helps identify which band is the tolerance band. You'll also notice that the red band is sitting on the shoulder whereas the last black band is spaced a little bit away from the shoulder.

But if my interpretation of that photo is wrong, and the order actually is brown, black, black, red, brown then you'll have a completely different value (10k ohm in this case) for the resistor.

So when there's any doubt about the resistor, you ought to use an ohmmeter to validate what you think the value ought to be.

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    $\begingroup$ To me it looks as if the bigger gaps are left and right of the red ring. So could this be 1-0-0 and multiplier 100 Ohm? If in doubt I'd always measurw it with a multimeter. $\endgroup$
    – ott--
    Aug 7 '16 at 19:13
  • $\begingroup$ @ott-- it's dangerous to read too much into small details of the layout of the coding rings. Sometimes you get a batch of components with "badly painted" rings. Unless the OP knows what component values are expected, and that rules out one possible interpretation of the coding, this is definitely an example of "check the value with a meter" IMO. $\endgroup$
    – alephzero
    Aug 7 '16 at 20:54
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    $\begingroup$ +1 for recommending double-checking with an ohmmeter. I'd extend this in general to : check every component, and check the power supply output before connecting to anything that could be damaged with the wrong voltage. $\endgroup$ Aug 8 '16 at 12:56

I happen to have 3 similar resistors (from the Arduino kit):

3 different resistors

I couldn't resist to measure them, so from left to right they 220 ohm, 1k ohm and (as I assumed) 10 k ohm.


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