Hey guys, Could you shed a little light on this problem here? I'm trying to calculate the half power frequency for these 2 circuits, and I'm not sure if my reasoning/math is right: For the former one, I did Fc=1/(2πR*C) where R=(R1*R2)/(R1+R2)+R3. Is this correct? Is this all? How about the latter one? Thank you

Hello Benny, You have to look from the capacitor into the circuit when you calculate the corner frequency or the time constant. Treat the voltage source as a short (0Ohm) for the calculation, because it has zero internal resistance. a) Lowpass Filter fc = 1/(2*pi*R*C) R = 1/(1/R1 + 1/R2 + 1/R3) b) Highpass Filter fc = 1/(2*pi*R*C) R = R1 + 1/(1/R2 + 1/R3) By the way you can simulate this circuit with LTspice to check the results. Best regards, Helmut

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