Filter design advice

[zachtheterrible]

Hi all,
I made a voice transmitter and receiver with 900MHZ linx modules, and it works great accept for the hisssss that overpowers small noises. I'm just using a regular ol' LM386 as my amplifier.

I want to make a 3khz low-pass filter. I just need some advice on what kind of filter would be the best? active, passive? LC, RC? I simply don't know where to begin with this :?

 

[Russlk]

A simple R-C filter should be all you need. Try 10K and 4.7nF If that is not enuf attenuation of the Hiss, put another section in cascade.

 

[ljcox]

Zach,
If that is not adequate, send me a PM and I'll design a simple LC filter for you.

All you need is one L and two C for a n=3 Butterworth filter.

Or, two L and 3 C for a n=5 (steeper slope)