# LC Filter Design

Discussion in 'The Projects Forum' started by lijoostenk, Jan 26, 2013.

1. ### lijoostenk Thread Starter New Member

Jan 25, 2013
12
0
I need to design a simple LC filter for eliminating the ac ripples at the output of a rectifier. My circuit involves series connected high power LED's which receives its input from the filter.
So I need a filter which can tolerate such high currents (>2A). Can anyone help me out in designing this filter?

2. ### antonv Member

Nov 27, 2012
149
27
A simple LC filter (series inductor followed by a parallel capacitor) may work fine. Important things to pay attention to are that the inductor has a saturation current of maybe twice the 2A and also low dc resistance, and that the capacitor can handle high ripple currents. How much depends on what your are driving and probably the frequency you are using.
How much inductance the inductor needs will also depend on your frequency. How well the whole circuit works will also depend a lot on how you wire it. Long wires in the wrong places can wreck the filter's performance.

3. ### thatoneguy AAC Fanatic!

Feb 19, 2009
6,357
728
For an RC filter, C is roughly:

$C=\frac{8.6}{f \cdot R \cdot Ripple%}$

C is in Farads, f is rectified frequency (100 or 120 Hz for 50 or 60Hz), %ripple is deviation from average voltage, R is load defined by: $\frac{Vout}{Iout}$.

4. ### #12 Expert

Nov 30, 2010
18,093
9,683
Inductors were used a lot, 50 years ago. They have been replaced by excellent, inexpensive capacitors. I would recommend you do not use any inductor at all unless this is a homework assignment.

In addition, LEDs are not very picky about the cleanliness of the DC power. A whole volt of ripple would not be a problem in this case.

5. ### crutschow Expert

Mar 14, 2008
20,494
5,803
The OP wants an LC filter.

Here's a reference that may help.

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