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

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01:56:43

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

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Filter Application I : Garbage detection:
see http://gollreiter.eu/aol_2L_2_3_filter_application_II_garbage.htm

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Reference: Thomas C. Hayes, Learning the Art of Electronics, Cambridge University Press, 2016, page 83

published 10 years ago

2ctiby

10 years ago

Looks good to me...you might want to set the 10kHz amplitude to 13v to be the same as that of the 50Hz

hurz

10 years ago

@rigo59, the biasing offset just looks as a DC at first view. Actually its the 50Hz signal, which is by native of such filter not 100% blocked, differential to a "-cos()" from the original 50Hz sin(). Watch a little longer and you notice the phase shift relation. Hope that helps.

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