-ve voltage generation 555

Discussion in 'General Electronics Chat' started by aamirali, Mar 7, 2012.

  1. aamirali

    Thread Starter Member

    Feb 2, 2012
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    I have checked -ve voltage generator by 555, here
    http://www.eleccircuit.com/12vdc-negative-voltage-dc-converter-by-555/

    But I don't understand why cap C4 whose +ve side is positively charged & -ve plate is grounded during positive cycle.
    Then why during 0V cycle, +ve plate is at zero & -ve side is at -vcc potential.
    Do charge gets transferred
     
  2. Jony130

    AAC Fanatic!

    Feb 17, 2009
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  3. Wendy

    Moderator

    Mar 24, 2008
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  4. buzaiandras

    Member

    Jul 18, 2011
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    If I understand it correctly (I might be wrong, I am a beginner) during the 0V cycle the +ve plate is brought to 0V potential by the 555 timer. But the +ve plate is still at a higher potential than the -ve plate. the capacitor is still charged. You can think of it as a change of reference for the voltage measurement.
    So if -ve is at a lower potential than +ve then when +ve is brought to 0V it means that -ve must be below 0. This is why it is at -vcc.

    Something similar happens with the capacitors in a astable multivibrator.
    Maybe somebody with more experience can shed light on this for us :)

    Thank you
     
  5. Jony130

    AAC Fanatic!

    Feb 17, 2009
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    Yes you are right
    http://forum.allaboutcircuits.com/showpost.php?p=200183&postcount=12
     
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