Building a 12 VAC to 5 VDC bridge...

Discussion in 'The Projects Forum' started by sd_sparky, Apr 27, 2009.

  1. sd_sparky

    Thread Starter New Member

    Oct 20, 2008
    6
    0
    I'm looking for a schematic for a small bridge rectifier to convert 12 VAC to 4.5-5 VDC @ approx. 10ma.

    Has anyone got anything like this they'd like to share or can anyone tell me where I might find a drawing for this?

    Thanks!
     
    Last edited: Apr 27, 2009
  2. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,536
    Not sure what you're looking for exactly, but this is a fairly basic power supply circuit. With such a low current a linear regulator is a pretty good choice, though you will probably want to heat sink the regulator chip.

    [​IMG]

    Bridges can be either bought as components, or built using discrete diodes.
     
    Last edited: Apr 27, 2009
  3. carcia

    New Member

    May 12, 2006
    2
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    It should be the short answer, congratulations..
    :D
     
  4. sd_sparky

    Thread Starter New Member

    Oct 20, 2008
    6
    0
    Thanks for your help!

    :D
     
  5. sd_sparky

    Thread Starter New Member

    Oct 20, 2008
    6
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    And am I correct to assume the diodes would be 1N4001?

    Thanks again for your help!
     
  6. gerty

    AAC Fanatic!

    Aug 30, 2007
    1,153
    304
    1n4001 would work just fine...
     
  7. gerty

    AAC Fanatic!

    Aug 30, 2007
    1,153
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    Also , in your case the regulator would be marked "7805" for a fixed 5 volt regulator.
     
  8. sd_sparky

    Thread Starter New Member

    Oct 20, 2008
    6
    0
    If I wanted to adapt this configuration to a different output voltage, how would I calculate the change in components? If I wanted to change the output to 3v dc, would simply changing the voltage regulator to 7803 do the trick?

    I don't mean to ask stupid questions... I just don't have the electronics background to complete a project.

    Thanks!

    :D
     
  9. sd_sparky

    Thread Starter New Member

    Oct 20, 2008
    6
    0
    One more question... What would be the maximum output of this circuit at 5v?

    Thanks.
     
  10. sd_sparky

    Thread Starter New Member

    Oct 20, 2008
    6
    0
    I found this second drawing on another site. It's very similar to the circuit posted by Bill Marsden. Bill's uses a 100μF capacitor and the other uses a 50μF and a 0.1μF in parallel.

    Is there any advantage or limitation to either design? Do both do the job equally well?

    Bill's Circuit
    [​IMG]



    New Drawing

    [​IMG]

    Also, This drawing shows the 50μF at 35v. I keep finding 25v and 50v capacitors, but no 35v. Would a 50μF 50v work?

    Thank-you!

    :D
     
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