sallen-key filter

D

D.M.

New Member

• Dec 6, 2009

• #1

can someone direct me to a page with fulfilling information about a SALLEN-KEY lowpass filter.

Please and thank you!

 

B

BrownOut

Banned

• Dec 6, 2009

• #2

Try this: Search for Sallen Key

 

D

D.M.

New Member

• Dec 6, 2009

• #3

you can be a smartass all you want.. i was asking more on the lines of preferred sights from other fellow electronics people.

 

jpanhalt

Well-Known Member

Most Helpful Member

• Dec 6, 2009

• #4

I don't believe there is a site devoted to Sallen-Key filer discussion.

TI has a free program, Filter-Pro, that will help you with the calculations. Unfortunately, I simply installed the program and don't have the URL for it. Try the TI site.

As for your characterization of BrownOut, I suggest you look within. Had you taken the few seconds it would have taken to better describe your needs, and I am sure BrownOut would have given more immediately helpful information to you. You reap what you sow.

John

 

Last edited: Dec 6, 2009

B

BrownOut

Banned

• Dec 6, 2009

• #5

I'm willing to bet the search turned up a bounty of useful information, for anyone who puts in the effort to sift through it. And the OP was given the TI link is another thread he originated.

 

Last edited: Dec 6, 2009

D

D.M.

New Member

• Dec 6, 2009

• #6

i was brash i understand and it was not necessary. it was rather funny you took the time to make that video instead of helping.

my post was rather vague, but i am swamped with work so i have little time to waste and i thought a quick post would be sufficient.

and i have researched many pages, i was just looking for preferred sights from anyone out there.

 

jpanhalt

Well-Known Member

Most Helpful Member

• Dec 6, 2009

• #7

I guess after a few tries, it appears that neither BrownOut nor I understand. What exactly do you mean by preferred sights?

Originally, I thought you meant "sites," but apparently that is not what you mean.

John

 

B

BrownOut

Banned

• Dec 6, 2009

• #8

He wants someone to provide a website that has information about S-K filters. In reality, a simple search turns up a boatload of information. Maybe it's too much information. (information overload)

 

jpanhalt

Well-Known Member

Most Helpful Member

• Dec 6, 2009

• #9

I guess he didn't understand what I meant by TI, as in ti.com. Here is the link:

Texas Instruments - Keyword Search Results

John

Edit: BTW, FilterPro is the first link; the other two discuss filters, including Sallen-Key.

 

Last edited: Dec 6, 2009

audioguru

Well-Known Member

Most Helpful Member

• Dec 6, 2009

• #10

I don't like Filter-Pro because it shows very odd resistor and capacitor values.
It has never made a Butterworth second order Sallen and Key filter with two resistors or two capacitors with the same value and it has never made a Butterworth Sallen and Key second order filter with the resistors with the sane value, or the capacitors with the same value plus some gain.

 

jpanhalt

Well-Known Member

Most Helpful Member

• Dec 6, 2009

• #11

@AG
Do you use the optional entry panel? I do a first pass, then pick a capacitor that I have and make a second pass. Odd resistor values are handled either by setting the series, or I just use a pair of resistors of the series that I have to get the calculated value.

John

 

audioguru

Well-Known Member

Most Helpful Member

• Dec 6, 2009

• #12

A Butterworth second order Sallen and Key filter is made with a unity gain opamp and one capacitor or resistor exactly twice the value of the other. FilterPro doesn't know that.

A Butterworth second order sallen and Key filter is also made with the same resistors and capacitors and the gain of the opamp about 1.6 times. FilterPro also desn't know that.

FilterPro is stupid.