If the
roll off was such that the strength was around 6 dB down
at 250 Hz. it
would satisfy my requirements. What I'm after is
reducing mains hum
and its first few harmonics to a level where
they are below the strength of
the desired signals, which fall in
the range of 1 to 4.5
kHz.
------------------------------------------
Take a look at this......
As it stands, it does have quite high passband loss, around 10dB, but less
stages could reduce passband loss at the expense of a less steep roll off.
There should be plenty of info online allowing you to design a simple CR
filter like this, it's standard textbook stuff, and there's probably sites where
you can just feed in your requirements and have it churn out the
results:-)
If you want lower pass band losses and sharper cut off then you would
probably need to consider active filters.
regards
Nigel
GM8PZR
