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Schematic diagrams with antiparallel diodes

Discussion in 'General Electronics Discussion' started by boogie, Aug 3, 2013.

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  1. boogie

    boogie

    2
    0
    Jul 13, 2013
    Hello everyone. I would like to now what is the role of the 2 antiparallel diodes in the circuit, D305 and D307, D918 and D919, from the 2 schematic diagrams below? I mention that the 2 schematic diagrams are from a CD player radiocassette device. Thank you in advance!
     

    Attached Files:

  2. BobK

    BobK

    7,682
    1,688
    Jan 5, 2010
    It limits the voltage to about + or -0.6V

    Bob
     
  3. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    May 8, 2012
    The Diodes in the RF input schematic (D305, D307) make sense to me but D918, D919 evoke questions. Why two of them (ying & yang) on that node? This is the common node of the bridge and is usually connected to GND for positive output voltage. As I see it this node can only swing negative anyway. Also, why 1N4148's, which are switching diodes? The bridge uses 1N4004 power diodes rated at 1A while the the 1N4148 is rated at ~200 mA, yet they share the same current.

    Sure would like to see the rest of this circuit.

    Chris
     
  4. davenn

    davenn Moderator

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    Sep 5, 2009
    would appear to be bringing Data Ground close to but not at the same potential as chassis ground. maybe they still want a modest amount of isolation between DGND and chassis GND ??

    Dave
     
  5. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    May 8, 2012
    Since I didn't see the entire schematic I thought it was a -700mV voltage source for something not shown in those two prints. Guess not.

    Chris
     
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