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I found a pile of these resistors, and I didn't know how to decode them using 4-band logic.

How do you know if it's to be read:

Brown(1), Black(0), Black(0), Black(0), Red(2) = 100Ohm

or:

Red(2), Black(0), Black(0), Black(0), Brown(1) = 200Ohm

Now before you get carried away, I hooked up a multimeter and I know that it is a 200Ohm resistor.

My question is, how would I be able to guarantee it is a 200Ohm resistor and not a 100Ohm resistor, using only the bands?

While looking for a picture to put with this post, it appears "grouping" plays a role on some 5-band resistors, but in this case there appears to be no grouping, but the red band is slightly thicker than the brown band. Is there a standard, or is this some form of tribal knowledge?

5-band, 200Ohm, blue resistor

Zak
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  • In todays industry, human identifiability of resistors is merely an artifact from the past. This means that no one cares much about if the bands are wrong/off. Especially with the blue ones, the colors often mix, making orange seem red or red seem brown or similar. Sometimes manufacturers also substitute one color for another because they ran out of it. – PlasmaHH Mar 25 '15 at 09:34

1 Answers1

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All of the bands are about the same thickness except for one. That would make me think that the odd band is the tolerance and the others are the value.

The more normal placement of the bands has them off-center. In that case, the band closes to the end of the resistor is normally the first digit of the value, with the rest following in order.

Your resistors are confusing and even though I would think that the value is 200 Ohms 1%, I'd still grab my multimeter and check the value - just to make sure.

Dwayne Reid
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