Rectifier filter

Discussion in 'General Electronics Chat' started by Kaiser Ed Bayawa, Feb 16, 2016.

  1. Kaiser Ed Bayawa

    Thread Starter Member

    Mar 19, 2015
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    I am having a problem with my power suppy. The 12v transformer, I used bridge rectifier and a capacitor 2200uF filter.
    But still the output is not smooth.
    Do you have any idea about this filter?
     
  2. ronv

    AAC Fanatic!

    Nov 12, 2008
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    It should work, but the ripple will depend on how much current you draw from the supply.
     
  3. #12

    Expert

    Nov 30, 2010
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    Sqrt2 C Eripple(p-p)F = I
     
  4. MrAl

    Distinguished Member

    Jun 17, 2014
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    Hi,

    Add more caps in parallel, that makes it smoother.
    To get very smooth you need a voltage regulator.
     
  5. cmartinez

    AAC Fanatic!

    Jan 17, 2007
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    Can you post a very simple, hand-drawn diagram of your circuit?
     
  6. wayneh

    Expert

    Sep 9, 2010
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    You've gotten two solutions, more capacitance or a voltage regulator. There may be other solutions if you give more details about the rating of the transformer and the load you need to power.
     
  7. Kaiser Ed Bayawa

    Thread Starter Member

    Mar 19, 2015
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    the transformer rating is 12V and 0.75A
     
  8. AnalogKid

    AAC Fanatic!

    Aug 1, 2013
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    With the schematic you posted, the output never will be "smooth". Ever. It always will have some ripple. Increasing the size of the capacitor will decrease the ripple amplitude, but it will not - cannot - eliminate it.

    ak
     
  9. dannyf

    Well-Known Member

    Sep 13, 2015
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    define "smooth".
     
  10. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    Define smooth = how much peak to peak ripple can you allow?

    If that is zero you need a voltage regulator. If some number tell us what The lad R is and we can show you how to calculate how much capacitance you need.
     
  11. alfacliff

    Well-Known Member

    Dec 13, 2013
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    your circuit is of a simple "brute force " filter. more capacitance is need for this type. even with a regulator, more filter cap would be needed to prevent the regulator fromj dropping out under load.
     
  12. Kaiser Ed Bayawa

    Thread Starter Member

    Mar 19, 2015
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    i used the term smooth for "no ripple voltage" or less fluctuation.
     
  13. dannyf

    Well-Known Member

    Sep 13, 2015
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    "no ripple voltage" and "less fluctuation" are two totally different things.
     
  14. cmartinez

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    Jan 17, 2007
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    The latter is readily attainable... but the former would be a holy grail hidden in neverland...
     
  15. ErnieM

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    Apr 24, 2011
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    For a 2200uF cap, 60 cycle full Wave bridge with the full load of 0.75ma one should expect on the order of 2.8 volts peak to peak of ripple.

    Doubling your cap halves that number. Ten times the cap drives it down to just 0.28 V p-p.

    (edited to add spec'd load current)
     
    Last edited: Feb 17, 2016
  16. wayneh

    Expert

    Sep 9, 2010
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    Those depend on the load. No load, (almost) no ripple. Loading at double the rating, big ripple, and the cap does little except increase the total load.
     
  17. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    My bad. Numbers are based on the quoted full load. Post 15 has been edited.
     
  18. wayneh

    Expert

    Sep 9, 2010
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    I knew what you meant. What we don't know is what the TS is doing.
     
  19. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    Understood. I was just trying to let MrAl know what was to be expected from his set up.
     
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