Comment on Resistor Identification

MrOtingocni@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

• jeinzi@discuss.tchncs.de ⁨2⁩ ⁨weeks⁩ ago

  Is this a thing? Have you encountered resistors with 5 color bands without a multiplier?

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  • MrOtingocni@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

    Personally? No. Mainly because while I have had to ID and work with resistors at work a few times, I am a hobbyist, and I haven’t worked on anything older than the 90s.

    Again, from an amateur perspective, the color codes we’re familiar with wasn’t globally adopted until 1969. We don’t know where or when this resistor was made. It even looks different from the others. Considering that the reading is very close to one of the interpretations you have from the coding, I would guess it’s non standard but close and probably within the intended spec. Again, grain of salt, etc.

    But check this out:

    Color Code Exceptions

    The color coded resistors are inserted in circuit boards, and the PCB assembly manufacturing is finished by thru-hole pin soldering.

    Reliability band: 
    

    Resistors that are produced according to military specifications, sometimes include an extra band to indicate reliability. This is specified in failure rate (%) per 1000 hours of service. This is rarely used in commercial electronics. Most often the reliability band can be found on four band resistors. More information about the reliability can be found in the US military handbook MIL-HDBK-199.

    Single black band or zero-ohm resistor:
    

    A resistor with a single black band is called a zero-ohm resistor. Principally, it is used as a wire link that functions to connect traces on a printed circuit board (PCB). Using the resistor package allows the same automated pick-and-place machines to place the components on a circuit board.

    5 band resistor with a 4th band of gold or silver: 
    

    Five band resistors with a fourth band of gold or silver form an exception and are used on specialized and older resistors. The first two bands represent the significant digits, the 3rd is the multiplication factor, the 4th is the tolerance, and the 5th is the temperature coefficient (ppm/˚C).

    Deviating colors: 
    

    For high voltage resistors, the colors gold and silver are often replaced with yellow and gray. This is to prevent having metal particles in the coating.

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    • jeinzi@discuss.tchncs.de ⁨1⁩ ⁨week⁩ ago

      Thank you very much for your detailled answer, this resolves my question and I can sleep peacefully again :) The device is also fixed; as I wrote in response to BigDanishGuy, the problem was caused by a connected pressure switch. The circuit board seems to have no issue at all.

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