Monday, 24 November 2014

Strange resistor colours


Normally this kind of thing wouldn't pose the slightest problem for me, but I am just trying to decipher the colours on a resistor.




  • Orange

  • Orange

  • Gold

  • Gold

  • Black


enter image description here


All the online tools tell me it's a 4-band 3.3Ω, but that ignores the 5th black band.


Yes, when I measure it it's 3.3Ω.



So how does the colour coding work for that then? Is it a 4-band with some mystery extra band? Or does that 5th band signify something special?



Answer



Alright, I finally found something that supports Spehro Pefhany's proposal. This is a common 4 band resistor.
The black band is there because both 3 and 4 band resistors aren't required to use gold and silver on the readings. Thus, some resistors can be read backwards (Yikes).


To solve this, the black band is put onto the resistor to tell which way it's supposed to be read. Later, this was replaced by deliberately spacing the bands, but it seems that some manufacturers still use the black band.


enter image description here


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