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Resistors, Capacitors, Zener diodes... Why the funny values?

An explanation of the E-series and why those funny values are used.

  1. FrankB


    Nov 19, 2018
    A bit of history here on odd resistor values like "400 ohms" etc:

    Back in the Dawn of Time when radios were first being produced, some factories used Sodium vapor lighting. Certain color identifiers (or Dots) back then were unreadable due to the color of the lighting.

    So companies like Philco, Atwater kent, and others used colors the assemblers could actually see in that type of light.
    It took me decades to find out the reasoning behind the odd values.

    You can prove this for yourself quite easily. Most cities have Mercury and Sodium vapor lights for street lighting in places. Take a handful of different value resistors and try reading the color bands on them in the different light types.
  2. duke37


    Jan 9, 2011
    An analogy of the odd values can be seen in the choice of frequency in the normal music scale.
    There are twelve notes in an octave - yes there are - and the difference in frequency between one note and the next is the twelfth root of two, about 6%. Multiply the frequency of a note by this increment twelve times and you will get double the frequency. Note A 440 Hz is the basic reference frequency.
  3. WA2YNE


    Nov 20, 2018
    I am one of those rare people who know a lot, but admit to not knowing everything.
    At 80 years old this month, I am still researching, searching and learning more stuffs.
    I started learning basic electronics about 1953 or 1954, when it was still mainlt tube.. The transistors were barely starting to be avaiale at the time.
  4. duke37


    Jan 9, 2011
    A mere chicken:) You will have to run to catch me up.
    The trouble with old age is that you have to learn the same thing over and over again.
  5. Terry01


    Jul 5, 2017
    At 80 years old and even older than 80 years old, I bet you know a lot of stuffs between you both! What you don't know you'll be able to make a wee porky up about something similar that you do know about and "wing it" and pretend you know everything! Ha Ha! :p
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