Capacitor Symbols (help)

Discussion in 'General Electronics Chat' started by morphemes, Jan 27, 2014.

  1. morphemes

    Thread Starter New Member

    Jan 27, 2014
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    [​IMG]
    I'm completely inexperienced, so forgive me if this is a no brainer, but I have no idea what this symbol means. I know that some of them are capacitors... & some of them are polarized capacitors, but the additional solid black line is throwing me off. I can't figure out where they're going. Are they wired from the circuit to nothing? Are they wired to ground or what?


    The schematic is for a bridged DMOS audio amplifier.

    Thanks for the help.
     
    Last edited: Jan 27, 2014
  2. t06afre

    AAC Fanatic!

    May 11, 2009
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    The single black line is a ground symbol. Not a symbol I would have used by the way
     
  3. blah2222

    Well-Known Member

    May 3, 2010
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    Single black line = ground
    White & black pair = polarized (white +, black -)
    Black pair = non-polarized
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
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    The additional black line is the chassis or power common signal, unfortunately the earth ground gets used extensively, regardless of whether the P.S. is at earth ground or not.
    There are at least four symbols for indicating the correct nature of the Power common.
    When the earth symbol is used without due consideration, it becomes meaningless.
    IMO, the schematic was drawn correctly.
    Incidentally you sometimes may come across a small value non-polarized cap with a line indicating the one side of the connection, this is in order that the outer foil is next to the chassis or power common, mostly relevant in HF/RF circuitry.
    Max.
     
  5. t06afre

    AAC Fanatic!

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    In which standard is that a correct ground symbol?
    Edit: It is actually within the IEC 60617 to use a single bar as symbol for chassis ground. However using this symbol in this case. Is slightly out of place
     
    Last edited: Jan 28, 2014
  6. MaxHeadRoom

    Expert

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    The alternative single bar with or without the 'hatching' has been in use in Europe for a few decades.
    I have come across quite a few N.A. manufacturers using it, also it is sometimes used filled in black as shown and open non-filled (White) in the same schematic to show two galvanically isolated circuits part of the same equipment.
    http://www.edrawsoft.com/electrical-symbols.php
    Max.
     
  7. #12

    Expert

    Nov 30, 2010
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    Anyway...you will have to learn to accommodate several styles of drawing that come from different places/countries. It won't be long until, "common sense" tells you what the symbol means.

    Two black bars over a third black bar? Not likely it's a three plate capacitor. Must be a "funny" ground symbol. When you get to the point that you're familiar with the working parts (input filters, feedback loops, etc.), the symbols that are not obvious will be very few and you will be able to figure them out from what they couldn't possibly be. It just takes a little while. ps, you will still find mistakes occasionally and have to figure out what the designer MEANT instead of what he drew.
     
  8. morphemes

    Thread Starter New Member

    Jan 27, 2014
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    In retrospect, it was kind of like trying to read having only known consonants. I was sure the vowels were there, but their symbols only confused & further degraded my ability to pronounce... Anyway, I kind of figured it meant ground, but I wasn't sure & my instincts regarding electricity shut down any ability to further conceptualize the circuit, least we set fire to the building & kill ourselves. It was driving me crazy. Now that I know, I shall never forget. Thanks for the help, everyone.
     
  9. MaxHeadRoom

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    Jul 18, 2013
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