AoE 2L.2.3 - Filter applications I and II - Selecting signals

Filter Application II Application II.1: (on the left hand side) A 10kHz sinusodial signal is superimposed with a 50 Hz signal (e.g. noise from a power line). The passive RC high-pass is designed to extract the 10 kHz signal. The results of the simulator match very good with my lab experiments. f3dB = 1 / (2 pi RC) ~ 1000 Hz A Question: You can see a time varying bias of the output signal - the green curve - around the 0 V level. How can this be fixed? Application II.2: (on the right hand side) The interpretation vice versa. A 50Hz sinusodial signal (from a power line) is superimposed with a 10 kHz noise signal. The passive RC low-pass is designed to extract the 50 Hz signal. f3dB ~ 50 Hz +++ Filter Application I : Garbage detection: see http://gollreiter.eu/aol_2L_2_3_filter_application_II_garbage.htm +++ Reference: Thomas C. Hayes, Learning the Art of Electronics, Cambridge University Press, 2016, page 83