RC Filter

I was able to fix some of my noise problems. I ended up having to tie all of the grounds to 1 common point. Long story...

I'd like to know more about the "simple" low pass RC Filters.

Say I'm using a Max186 which I have. An I want to sample a 0-5 volt input signal, at a frequency on 5 times per second. How do I come up with the values to give me a nice stable reading?

Most of the tutuorials are based on Audio Filters and deal with decibals, input freq, output freq, response time..... Blah Blah. I have no clue what most of that is or how it's applied to a simple ADC Input Filter which isn't too simple for me.

Please help