# filters

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### #1 ng

ng

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Posted 18 June 2005 - 03:33 AM

hi all,

can someone give a simple explanation on band pass,bandstop and resoant filters?

Thanx for all and any help!

### #2 marke

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Posted 18 June 2005 - 10:58 PM

Hello ng

A band pass filter will allow information through between a lower frequency and an upper frequency but block frequencies outside this window.
A band stop filter does the opposite, it blocks frequncies between a lower and upper frequency.
A resonant filter allows one frequency through only.

Best regards,

### #3 ng

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Posted 19 June 2005 - 01:56 AM

Thanku mark

Yes i do know that.i was hoping to get the working method.I mean how the capacitor and inductor works.is there a parallel and series confugiration for these type of filters?

### #4 marke

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Posted 19 June 2005 - 02:16 AM

Hello ng

This is not really something that can be explained in a couple of posts on a forum. It is a complex topic and there are many different configurations depending on the characterisitics required.
I would suggest that you need to get hold of a text book on the subject and have a good look at that.
The capacitor and inductor have an AC impedance known as the reactance of the component and these influence the characteristics of the filter or circuit.
If you have one inductor and one capacitor and the reactances are equal, the circuit will be as resonance and can be used as a resonant filter. -shunt connected for a high impedance or series connected for a low impedance.
The reactance of a capacitor is 1/(2 x pi x f x C) and the reactance of an inductor is 2 x pi x f x L

Best regards,

### #5 ng

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Posted 20 June 2005 - 09:02 AM

Okay ,Shall do that.But i hope to get some of my doubts cleared when i am reading...
Thanx for ur help and time,Mark.

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