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Light blue resistors with 5 band codes?

Discussion in 'Electronic Basics' started by royalmp2001, Dec 7, 2005.

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  1. royalmp2001

    royalmp2001 Guest

    Hi everyone,
    What are the light blue resistors? Metal film maybe?
    I have some with bands:
    Brown - Green - Black - Red - Brown that read 15K on my ohmmeter.
    The fourth band confuses me - it is definitely red not orange - any
    ideas why?
    Oh, and there is a red spot that joins the red and the brown.

    Similarly I have some 8.25K resistors that are:
    Grey - Red - Green - Brown - Brown with a red dot joining the two
    I'd expect the fourth band to be red not brown.

    Also any idea who makes these?
  2. PeteS

    PeteS Guest

    1% resistors have 5 bands, not 4.

    The sequence is

    Digit 1, Digit 2, Digit 3, Multipler, Tolerance

    (Unlike 5% or lower resistors that have only 2 digits identified).

    Grey, Red, Green, Brown, Brown is:
    8 2 5 x10^1 1%
    8.25k, 1%

    A number of manufacturers make them. Try Vishay Dale, KAO-Speer and
    Bourns for starters.


  3. PeteS

    PeteS Guest

    Incidentally, the red spot joining the last bands is an orientation
    mark so you read it the right way around. The dot will be between the
    multipler and the tolerance band.


  4. Impmon

    Impmon Guest

    Also wouldn't an all blue resistor indicate flame proof or something?
    5 band 1% resistor are not common and usually are used by the
  5. Don Bruder

    Don Bruder Guest

    I've caught that bit of... information? scuttlebutt? urban legend?
    myself a few times through the years. Haven't ever found a definitive
    "That's reality" or "That's a crock" verdict on the concept, though.
    According to the way I've most often heard it, the "regular" resistors
    are just that - "regular" - Overload 'em, and they'll go up in smoke,
    possibly in literal flames as the carbon burns up. The pale blue ones
    are supposed to be non-flammable (They'll get hot and cook off if
    overloaded, but won't actually burst into flames, although they might
    get hot enough to touch off any flammable/explosive atmosphere
    surrounding them when they do) and the green ones are supposed to die
    without flames OR getting hot enough to ignite most flammable or
    explosive atmospheres they might be found in.
  6. Pooh Bear

    Pooh Bear Guest

    Resistors with 4 bands don't use the same multiplier as those with 3
    bands 'cos there's an extra digit provided by the extra band.

  7. Pooh Bear

    Pooh Bear Guest

    Flame proof Rs are normally made with a 'cement' coating and it looks like
    it. Typically dull grey and a slightly rough surface finish.

  8. Rich Grise

    Rich Grise Guest

    I saw a lot of blue 5-band resistors in the military. I have no idea what
    the difference is, other than costing 10X as much as ordinary parts. ;-)

  9. Rich Grise

    Rich Grise Guest

    Me, Too!

  10. Rich Grise

    Rich Grise Guest

    I want to bring up semantics here. What do you mean by "the same
    multiplier"? It still is "the number of zeros after the other digits",
    isn't it? But it'll be one less than the 5% Rs, because of the other
    digit. For example, a 22K 5% would be red, red, orange, <whatever the
    5% color is>, and a 22K 1% would be red, red, black, red, <apparently
    brown for 1%>.

    So the properties of the multiplier are the same, it's just not the same
    numeric value because of the additional digit.

    That's what you meant, right? :)

  11. PeteS

    PeteS Guest

    I would differ here. I have worked at a number of places where we used
    5 band (1% and 2%) resistors all over the place, back in the days I
    still commonly used through hole parts.


  12. Impmon

    Impmon Guest

    That is correct, the multiplier stays the same with both 4 and 5 band
    resistor. And FYI the 5% would be gold band. Silver is 10% and if
    you come across 3 band resistor, assume 20% tolerance. Red is 2 and
    brown is 1. I think there's also black for 0.5%.
  13. I can't speak to the flame-proofing bit, but the last time I
    ordered regular commercial-grade 1% resistors from DigiKey, they had
    blue bodies and five color bands.

    My point is that five-banders are likely much more common than you
    may have been led to understand.

    Keep the peace(es).

    Dr. Anton T. Squeegee, Director, Dutch Surrealist Plumbing Institute.
    (Known to some as Bruce Lane, ARS KC7GR,
    kyrrin (a/t) bluefeathertech[d=o=t]calm --
    "If Salvador Dali had owned a computer, would it have been equipped
    with surreal ports?"
  14. Pooh Bear

    Pooh Bear Guest

    Yup ! :)

    As in you might expect to see an orange band multiplier for a 47k but instead
    it's red.

  15. Pooh Bear

    Pooh Bear Guest

    Goodness. I can't even remember when I last saw a silver band.

  16. ehsjr

    ehsjr Guest

    Grumble. On the blue resistors I can't tell the difference between
    the colors, patricularly brown, red and orange. :-(
  17. Rich Grise

    Rich Grise Guest

    If it's not a color-blindness issue, I've found that a 3X RS magnifying
    glass is very, very helpful. Our color receptors don't really have
    that fine of a resolution, but if the item is big enough to hit more
    than one or two cone cells, it should clear right up. :)

    Good Luck!
  18. ehsjr

    ehsjr Guest

    Thanks! Gotta try that. Circuits don't work
    too well when you stuff a 470 in instead of a 47 K.
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