Quote Originally Posted by mister_e
look at
http://www.chem.uoa.gr/applets/Apple...xt_OpAmps2.htm
http://www.allaboutcircuits.com/vol_6/chpt_6/6.html
http://webpages.ursinus.edu/lriley/r...html#fig:opint


and ... LMAO!!! a really quik one
http://lhcb-elec.web.cern.ch/lhcb-el...s/00000031.htm
I checked these links and found to be very preliminary.
U should check the National Semiconductor's Opamp Circuits Application
note. If Ur input frequency is fixed then use Bandpass filter -Besel or Chebishev type tuned to that frequncy as centre of bandpass.With LM324
U can do upto 2-300Hz but with TLO64 or better U can go to 10Khz. With
the quad opamp U can make 2stage filter with very low distortion.U may
need additional gain stage for final output.