Active notch filter

[5th element]

http://www.linkwitzlab.com/filters.htm#7

This shows a notch filter.

Does anyone know the design formula for design B?

Am I being an idiot and not recognising that its actually there?

Cheers for any help Matt

 

[moamps]

Hi,

http://www.linkwitzlab.com/images/graphics/inductr2.gif

Regards

 

[5th element]

Yes that tells you how to calculate the value of the inductor.
But what about the frequency it all works at?
The Q of the notch? and
The size of the notch (db)?

I knew about that bit but not the rest.

 

[jackinnj]

Yes that tells you how to calculate the value of the inductor.
But what about the frequency it all works at?
The Q of the notch? and
The size of the notch (db)?

I knew about that bit but not the rest.

You should probably step back for a minute and take a look at some of the tutorials on filter design.

TI has a good tutorial on their website.

 

[5th element]

Look I have used active filters in the past to great effect and am in the process of building another. I know how to use them. This project tho calls for a notch filter which I have never had to use before. So hence I dont know how to calculate one. All I need to know is the formulas. If TI has this which I will look into then great. I was just wondering wheather anyone knew the formula LW has used in that notch.

 

[jackinnj]

I don't think that Linkwitz changed any of the principles of electrical engineering.

Q = w0 RC

 

[moamps]

Gyrator (simulate inductor)

http://www.national.com/an/AN/AN-435.pdf

 

[JensRasmussen]

I think there is an error here ?

Hi,

The drawing has an error I think.

The parallel resistor across the inductor needs to be R2-R1.

http://www.linkwitzlab.com/images/graphics/inductr2.gif

\Jens