# Rectifier filter

#### Kaiser Ed Bayawa

Joined Mar 19, 2015
64
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.

#### ronv

Joined Nov 12, 2008
3,770
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.
It should work, but the ripple will depend on how much current you draw from the supply.

#### #12

Joined Nov 30, 2010
18,224
Sqrt2 C Eripple(p-p)F = I

#### MrAl

Joined Jun 17, 2014
10,595
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.
Hi,

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

#### cmartinez

Joined Jan 17, 2007
8,098
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.
Can you post a very simple, hand-drawn diagram of your circuit?

#### wayneh

Joined Sep 9, 2010
17,405
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.

#### Kaiser Ed Bayawa

Joined Mar 19, 2015
64
the transformer rating is 12V and 0.75A

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#### AnalogKid

Joined Aug 1, 2013
10,563
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

#### dannyf

Joined Sep 13, 2015
2,197

#### ErnieM

Joined Apr 24, 2011
8,362
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.

#### alfacliff

Joined Dec 13, 2013
2,458
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.

#### Kaiser Ed Bayawa

Joined Mar 19, 2015
64
i used the term smooth for "no ripple voltage" or less fluctuation.

#### dannyf

Joined Sep 13, 2015
2,197
i used the term smooth for "no ripple voltage" or less fluctuation.
"no ripple voltage" and "less fluctuation" are two totally different things.

#### cmartinez

Joined Jan 17, 2007
8,098
"no ripple voltage" and "less fluctuation" are two totally different things.
The latter is readily attainable... but the former would be a holy grail hidden in neverland...

#### ErnieM

Joined Apr 24, 2011
8,362
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:

#### wayneh

Joined Sep 9, 2010
17,405

#### ErnieM

Joined Apr 24, 2011
8,362
My bad. Numbers are based on the quoted full load. Post 15 has been edited.

#### wayneh

Joined Sep 9, 2010
17,405
I knew what you meant. What we don't know is what the TS is doing.

#### ErnieM

Joined Apr 24, 2011
8,362
Understood. I was just trying to let MrAl know what was to be expected from his set up.