I have two resistors that I'm trying to figure the values of.
One is black blue silver gold black
Second is black orange silver gold black
Can anyone help with these values?
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\$\begingroup\$ What's "blk"? Black? \$\endgroup\$– winnyCommented Mar 19, 2019 at 16:19
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\$\begingroup\$ Try 6.8 ohms and 3.9 ohms (Black is possibly the base colour of the resistor and silver is possibly grey and you may be mistaking the other silver for white). \$\endgroup\$– Andy akaCommented Mar 19, 2019 at 16:19
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\$\begingroup\$ I do apologize for having to edit the blk. I was able to upload an image of them just in case. \$\endgroup\$– PatCommented Mar 19, 2019 at 19:34
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\$\begingroup\$ @Pat - Hi, (a) Have you tried measuring them with a multimeter? If so, what did you measure? If not, what is preventing you measuring them? (b) What is the context to the question? There is no obvious sign of damage, so why are you trying to find their values? I just want to avoid the situation where you do find their values, but that turns out not to help with some other underlying problem, which hasn't been explained yet... Thanks. \$\endgroup\$– SamGibson ♦Commented Mar 19, 2019 at 21:01
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\$\begingroup\$ @SamGibson I have measured them and they measure .8-.9 ohms (the pink resistor) and the blue is .11 ohms. These are out of a computer power supply that stopped working. I replaced a bad capacitor and checked two diodes and these two resistors that were part of that circuit, the diodes tested fine but these two resistors seemed way off. \$\endgroup\$– PatCommented Mar 21, 2019 at 0:07
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2 Answers
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These are most likely 6.8Ω or 6.9Ω and 3.8Ω or 3.9Ω non-inductive type resistors. What you are calling silver is most likely either grey or white.
The final black band means non inductive type, and while gold is often a tolerance indicator, in this case it is the multiplier (0.1X).
See this chart:
answered Mar 19, 2019 at 16:25
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\$\begingroup\$ Interesting suggestion, however: "non-inductive type resistors" - those components (if they really are resistors and not inductors) appear to show the shape expected of a wirewound element under the paint, don't they, which would be inductive. So I can't reconcile the shape of the resistors (looking just what I'd expect for being constructed as wirewound) with that decoding (claiming they are non-inductive). See what I mean? I'm open to being shown that they are definitely non-inductive, if there is some evidence, so I could be wrong - but I can almost see the wire in them... \$\endgroup\$– SamGibson ♦Commented Mar 19, 2019 at 21:06
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2\$\begingroup\$ @SamGibson They are what is called bifilar-wound. They are coiled, but in both directions overlapping so the fields cancel. They do indeed look wire-wound, because they are! This is why the black band is needed, to alert you to the fact that although they LOOK like they would be inductive, they are not. \$\endgroup\$ Commented Mar 19, 2019 at 21:27
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1\$\begingroup\$ @evildemonic I think you're right about them being non-inductive wirewound: You can see the surface texture in the photos with the intersecting windings. \$\endgroup\$– TheodoreCommented Aug 9, 2021 at 14:43
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For others that find this topic: the gray resistor is 30mohm, the pink is 60mohm (+-5%, non-inductive). These are fusible resistors, they are usually used in pulse power supplies to limit max currents and as a fuse at the same time.
evildemonic band color chart is correct, his interpretation is wrong.
The values I gave are inferred from that chart:
black, orange, silver, gold, black (03 * 0.01Ω, +-5%, Non Inductance)
black, blue, silver, gold, black (06 * 0.01Ω, +-5%, Non Inductance)
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\$\begingroup\$ It would be more helpful if you added an explanation of the how you came up with those values and also what the specified tolerance is, since that's very important for these parts. \$\endgroup\$– LundinCommented Aug 9, 2021 at 11:43
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\$\begingroup\$ I thought this is obvious. evildemonic gave band codes chart above, it's just his resistor band colors interpretation that is wrong. \$\endgroup\$– KrzysiekCommented Aug 9, 2021 at 13:01
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3\$\begingroup\$ In all fairness, it isn't obvious which side of the component body to read from. Color coded resistors might just be one of the dumbest inventions in the history of electronics... \$\endgroup\$– LundinCommented Aug 9, 2021 at 13:13