how do i make a 1440hz filter

[jjfabiszak]

I am looking to see if anybody knows where I can find the schematics for a 1440hz filter. I have two audio frequencies a 1440hz and 2670hz frequency on one line and need to filter out the 1440hz frequency to verify that the 2670hz frequency is indeed 2670hz. Thank you guys very much...

 

[penrico]

What order?
Do you need active filter or passive filter?
You should use filter softwares. I recomend filter free, you can design and simulate, all kind of filters.

see filter free page at:

www.nuhertz.com


Good luck

 

[jjfabiszak]

I am not sure if it should be an active or passive filter.... all i know is that there are two frequencies on this one line and i am trying to troublehshoot it by verifying that the two frequencies on this line are in fact the correct frequencies of 1440hz and 2670hz... my theory is that if i make a filter that will filter out the 1440hz frequency than i will be able to see the 2670hz on a o-scope and verify the correct frequency.. .is this not accurate? does anybody know a better way to do this?

 

[penrico]

I think the better choice is a notch filter. Some time ago I made a notch filter for 9500hz, and have other frequency of 12000hz that I had to see. Let me if I can found that circuit, maybe it could be enoght for you.

Added after 6 minutes:

Here I found. I change the values to get 1500hz

Added after 10 minutes:


Changing the values, you can get better or worse Q. Just play for a little time, and try some values in the simulation. The circuit work very good.

 

[Kral]

jjfabiszak,
See the articel "Closing the Loop Deepens Notches" at **broken link removed**.
Regards,
Kral

 

[joker12]

Beware, the filter posted has a relatively wide notch for your application and the 2.67KHz signal would be attenuated by about -10dB.