Bridge rectifier question

Discussion in 'General Electronics Chat' started by DougB, Dec 2, 2010.

  1. DougB

    Thread Starter New Member

    Sep 11, 2010
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    0
    My project requires that I be able to power it with a 12 VDC supply. My 12 VDC can come either from a battery or a rectified AC source depending on the availability of a source. If I connect a battery directly to the output of the bridge rectifier (no AC available on the input of the bridge), do I hurt anything((bridge, battery, transformer) or do I need to isolate the bridge when the battery is used?
     
  2. #12

    Expert

    Nov 30, 2010
    16,345
    6,829
    That will work. Just connect the battery. A bridge rectifier will not let DC flow backwards through it.
     
  3. radiohead

    Active Member

    May 28, 2009
    474
    31
    You can also use the bridge rectifier as reverse polarity protection. Connect the output of the bridge to the circuit you want to protect, and the polarity of the DC input to the bridge doesn't matter, the output will always be correct.
     
  4. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    The polarity protection is a good point. The only thing you need to remember is that you'll get about a 2 volt drop in voltage depending on the rectifier (1.5-2.3-ish volt drop from 2 diodes).
     
  5. tyblu

    Member

    Nov 29, 2010
    199
    16
    If the battery voltage is less than the peak AC voltage, it will have to be protected as well just in case they are connected at the same time. Another diode!
     
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