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Why strange 0.047 uF value of caps

Discussion in 'Electronic Basics' started by Ignoramus20083, May 14, 2007.

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  1. Why are so many caps spec'ed as 0.047 uF or multiples thereof, thanks
     
  2. Capacitors and resistors (and usually inductors) are made
    with "strange" nominal values that are equally far from each
    other on a percentage basis. A .047 uF 10% tolerance cap
    can vary between .047/1.1 and .047*1.1 or .043 and .52 uF.
    The next lower 10% value would be a .039 uF, since it can
    vary anywhere between .35 and .043 uF. The next higher 10%
    value is .056 uF since it can be between .051 and .062 uF.

    Here is a table of all the standard values for various
    tolerances:
    http://www.logwell.com/tech/components/resistor_values.html
     
  3. They aren't. .047 is an E24 series number.
     
  4. Eeyore

    Eeyore Guest

    It's because component values are oganised (roughly) as percentage increases
    compared to the next value with 6,12, 24, 48 or 96 increments in a decade (
    known as E6 values, E12 etc... ).

    so the E6 values run for example

    1, 1.5, 2.2, 3.3, 4.7, 6.8 (where each value is about 1.5 times the
    previous one)
    10, 15........
     
  5. Chris

    Chris Guest

    And these overlap for different tolerances. So, if you needed only
    20% tolerance:

    1 = 0.8 to 1.2
    1.5 = 1.2 to 1.8
    2.2 = 1.76 to 2.66
    3.3 = 2.64 to 3.96
    4.7 = 3.76 to 5.64
    6.8 = 5.44 to 8.16
    10 = 8 to 12

    and so on. The E12s overlap at 10% tolerance, and the E24s overlap at
    5%. Caps tend to be specified at 20% tolerance, which makes 4.7 a
    very common value.

    Cheers
    Chris
     
  6. Marra

    Marra Guest

  7. John Fields

    John Fields Guest

     
  8. Marra

    Marra Guest

    Yes you can by adding components in series or parallel !

    Where do you think the values come from !
     
  9. John Fields

    John Fields Guest

     
  10. Marra

    Marra Guest

    Yes and I am becoming intolerant of you !
     
  11. John Fields

    John Fields Guest

     
  12. neon

    neon

    1,325
    0
    Oct 21, 2006
    values for all things comes not from the manufacture whims but rather from another source US goverment and since they are the big users of these things we are stuck with them.
     
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