# 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
60
6
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.

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
16,685
7,322
Sqrt2 C Eripple(p-p)F = I

4. ### MrAl Distinguished Member

Jun 17, 2014
2,554
515
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
3,698
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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
60
6
the transformer rating is 12V and 0.75A

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8. ### AnalogKid Distinguished Member

Aug 1, 2013
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1,297
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
2,196
417
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
2,449
428
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
60
6
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 AAC Fanatic!

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 AAC Fanatic!

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.

Last edited: Feb 17, 2016

Sep 9, 2010
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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.