Caps in bridge rectifier

Discussion in 'The Projects Forum' started by tubeman, Feb 28, 2009.

  1. tubeman

    Thread Starter New Member

    Feb 27, 2009
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    I am building an 80 watt guitar amp. I have built several amps from scratch and have repaired more than I can count. Most all have been pre 1970's. I got a P-Xformer from a later Fender design that used a bridge rec.. The schematic shows .002μF caps across each diode in the bridge. I have searched the web for data on this type of bridge but can't find a thing. Does anyone know what these caps do ? I have attached a schematic showing this power supply type. I am not building this amp. Tubeman
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Small caps like that are sometimes used across power rectifiers to "buy time" for them to switch on and off. I think they were included in this schematic to help reduce/eliminate a 120Hz "buzz" that might otherwise occur due to the relatively slow rectifier switching times.

    It's easier to eliminate noise at the source rather than try to compensate for it elsewhere.
     
  3. tubeman

    Thread Starter New Member

    Feb 27, 2009
    2
    0
    Thank you SgtWookie , I was hoping that it was something simple like that. Thanks for the quick reply. tubeman
     
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