Stereo bandpass filter

[billman]

Hi,

I am trying to tune my car and made an adapter cable from the factory knock sensor to a small stereo jack.

I sounds good but i would like to interfere a bandpass filter so i only hear the frequency i am interested in (in this example 6900-7200 Hz).

Can someone help me out here since circuit design is not my field? :-)

I would not mind if it would also amplify the signal and gave me earphone output. (if there is a ready cheap solution, let me know).

thanks

[billman]

Nobody??

[Frank Berry]

Please give us more information.
Depending on the steepness of the lower and upper cutoffs, the filter could take several stages.
How much do you need to attenuate the audio below 6900Hz and above 7200Hz?

[billman]

lets say from 0 to 6800 and from 7200 - 40000 the less the better.

The frequency under 6800 and above 7200 is not of importance. Center should be 7000hz.

The expensive devices that meant to do this job are using "passive noise canceling".....whatever that means.

[Frank Berry]

You might be able to find a 7000Hz ceramic filter that would give you a very narrow bandpass.
I'll work with my engineering software to see if I can come up with an IC-based filter that might work for you.
Please email me so that we can communicate.
I'll work on a filter design and email my results to you.

frankberry99@gmail.com