Electronics > Beginners
LPF question
stoica adrian:
Hello,
I have two qestions, if you can help me.
What happens after you pass the 3db point of a LPF, and witch is the maximum ° that you can obtain with a LPF?
Bassman59:
--- Quote from: stoica adrian on July 13, 2018, 03:00:38 am ---Hello,
I have two qestions, if you can help me.
What happens after you pass the 3db point of a LPF,
--- End quote ---
Pass it from which side? To the right (increasing frequency) of the 3 dB point, the response increases towards unity, at which point it flattens out. To the left of the 3 dB point, the response decreases with a slope given by the number of poles in (the order of) the filter. One pole, your attenuation goes as 6 dB/octave. Two poles give an attenuation of 12 dB/octave, and so forth.
--- Quote ---and witch is the maximum ° that you can obtain with a LPF?
--- End quote ---
That too depends on the order of the filter.
Circlotron:
RC low pass filter output would approach 90 deg phase lag, I expect.
Probably never quite get there.
David Hess:
90 degrees maximum per pole or order.
Audioguru:
A single R and a single C makes a very poor filter. it rolls off at only 6dB (half the level) for each octave (10 times the frequency). Use an opamp or a few to make a multi-order active filter.
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