# Beginner question about LC filters

Discussion in 'General Electronics Chat' started by turkeybuzzard, Mar 24, 2011.

1. ### turkeybuzzard Thread Starter New Member

Mar 23, 2011
3
0
Hi -- I'm trying to understand how LC band-stop filters work and hope someone might be able to help:

Here's the circuit:

http://dl.dropbox.com/u/7372632/Circuit.pdf

1. If the AC source is at frequency f and the Rs are equal resistance and each F is an LC parallel band stop filter tuned to frequency f, then are the currents across all three resistors the same (at all frequencies)? Is the oscillating current inside each F the same? Symetry would suggest that all the LC filters behave the same and all the resistors behave the same, right?

Dave

2. ### Wendy Moderator

Mar 24, 2008
20,993
2,731
Welcome to AAC.

This should have been in the general electronics chat, as it is electronics, not physics.

A moderator will be along shortly and move it. Please do not start a second thread, as one of the two similar threads will have to be closed.

Filters are a deep subject, the math can be highly complex, and leans heavily on the square root of -1 (called an imaginary number, and is denoted by j .

I don't know your math background, or how far your studies have gone.

Ignore the resistors for the moment, calculate the impedance for a series LC circuit and a parallel LC circuit at resonance. The calculate the voltages across each component (this has elements of a trick question, the answers will surprise) on the series LC at resonance.

Last edited: Mar 24, 2011