Pi Filter

[polus]

Im building a interface board which will be operating in a noisey enviroment and so, would like to filter the input.

Ive read about PI filters but am not sure exactly how to calculate the values required.

Theres a diagram here:
http://www.tpub.com/content/neets/14178/css/14178_164.htm

Are they known by another name becuase I cant find much in the search engines?

Thanks.

 

[audioguru2]

Hi Polis,
I think a pi filter has two capacitors and an inductor between them. Your circuit is an LC lowpass filter.
I searched Google for LC Power Supply Filter and got many links. This one shows that the LC filter must have the proper load or it will be resonant:

View attachment 40017

 

[polus]

Thanks Audiguru.

Ill have a look