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Can someone please explain parts of this diagram

Discussion in 'General Electronics Discussion' started by wedagedara, Sep 11, 2012.

  1. wedagedara

    wedagedara

    6
    0
    Feb 9, 2012
    Can someone please explain parts of this diagram

    VISIT HERE

    Please tell me what is:
    R1:
    R2:
    R3:
    C1:
    C2:
    And what are the four diodes used(in4xxx)
    My electronic knowledge is not so good. I just need to repair my lamp.
    Thanks a lot
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    9,367
    1,903
    Nov 17, 2011
    The four diodes are a bridge rectifier. Input pins 1 and 3 are AC, output pins 2 and 4 are DC.
    R1, C1 and R3 are current limiters. C1 operates on the AC side. The value 334 means 330nF. At 50 Hz this is equivalent to ~10kOhm. A capacitor is used instead of a resistor because it has lower power loss due to the phase shift between current and voltage.
    R2 is for safety reasons. It discharges C1 when the lamp is turned off.
    C2 is a smoothing capacitor. The DC voltage after the rectifier still has a large AC voltage superimposed which is reduced by C2.
     
  3. wedagedara

    wedagedara

    6
    0
    Feb 9, 2012
    No, i didn't meant to explain their works. I just asked what are the values of them(Eg: 10K, 33uF, etc). So it useful to buy them from a shop. The diagram is not clear to identify them,
    So please tell me what are R1, R2, R3, C1 and C2.
    Thanks
     
  4. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    Sure it is...

    [​IMG]
     

    Attached Files:

  5. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    resistors are in ohms. C1 is 0.33uF and must be mains rated.
     
  6. wedagedara

    wedagedara

    6
    0
    Feb 9, 2012
    Thanks a lot
     
  7. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    Generally recommended that C1 be 1.5-2.0 times or better than the mains rated in this application... This is to help compensate for transients in the mains supply...
     
  8. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    When I say "mains rated" I mean that the capacitor is rated to be placed across the mains.

    And my meaning was clearly not clear. So, for the benefit of wedegedara:

    The lowest of these is Class X (there are also X1 and X2 with higher ratings).

    See here.
     
  9. Harald Kapp

    Harald Kapp Moderator Moderator

    9,367
    1,903
    Nov 17, 2011
    YOu could have asked that, but your question wasn't that unambiguous.
     
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