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LC Filter and Capacitor Considerations [closed]


closed as unclear by ‭Olin Lathrop‭ on Sep 2, 2020 at 18:44

This question cannot be answered in its current form, because critical information is missing.

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I've been experimenting with LC filter circuits on the output of a SMPS I recently bought because it was too high for the circuit I'm making. After hooking up many different combinations, I found that this PI filter worked best for my load:

LC PI Filter

I'm trying to understand why this worked better than the two ceramic capacitor setup. My guess is the low ESR = more ringing? Is it standard to use electrolytics with this kind of filter? I guess I was really hesitant to use it because I couldn't find any examples online of electrolytics being used and the internet keeps shouting about how great MLCCs are.

P.S. Is it also better to use 3x22uF electrolytics instead or one bigger 68uF one?

Why should this post be closed?


Worked better than what? Show the other circuits, then it should be easy to explain why this one filters the ripple better. Also, tell us the ripple frequency you are trying to filter out. ‭Olin Lathrop‭ 19 days ago

So the only thing you changed was cap chemistry, not the capacitance? What does the layout look like? THR or SMD? X5R, NP0? ‭Lundin‭ 19 days ago

"on the output of a SMPS I recently bought because it was too high for the circuit I'm making" What does it mean for an SMPS to be "too high"? Do you mean it's output voltage? Are you trying to lower the voltage with a filter? At first I thought you were trying to filter out ripple, but on closer look that doesn't seem to be the case. I'm closing this mess until you fix the question to be more clear and address the issues raised in the comments. ‭Olin Lathrop‭ 18 days ago

"I'm closing this mess" @OlinLathrop, bringing the rudeness SE was famous for. ‭Chuck‭ 17 days ago

@Chuck If you don't like it, find your way back to SE. ‭Kranulis‭ 17 days ago

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