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[SOLVED] Resistor marked value vs. actual outside tolerance?

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RobAinscough

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I purchased a variety pack of resistors 1/4w 1% tolerance ranging from 0\[\Omega\] to 10M\[\Omega\]. I haven't tested every single resistor, but I did test many in the lower end from 0.5 to 10\[\Omega\] and most of them were not as marked and outside tolerance ... for example:

0.5 marked was 0.8 actual resistance
1.0 marked was 1.3 actual resistance

outside the 1% tolerance ... once I got above 10\[\Omega\] marked they started to fall within tolerance.

Is this common? Just a bad resistor manufacturer or something else?

Cheers, Rob.
 

andre_teprom

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Note that the same difference of above 0.3Ω happens in both, don't seem it could be due to the resistance of the multimeter cable?
 

c_mitra

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Resistances smaller than 1 ohm may be tricky to measure accurately with a conventional multimeter. You need to use a 4-point probe.

But I am surprised that resistors in the range 1-10 are also not showing accurately. Did you check with the multimeter specs?
 

RobAinscough

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Thanks for the responses, took me a while to check with my Oscilloscope, but it does indeed seem to be my DMM has about 0.3\[\Omega\] in cables and/or internal ... Mystery solved.

Cheers, Rob.
 

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