I built the following circuit and I would like to calculate the gain. I would like to predict the output voltage by knowing the input voltage. Also, I would like to predict the phase shift.
I got the transfer function from this question:Deriving 2nd order passive low pass filter cutoff frequency
I use this website to do math quickly instead of using my own calculator. The website provide the same transfer function of the previous question: http://sim.okawa-denshi.jp/en/CRCRtool.php
Here is how I use the website: I set the range of frequency from 999 to 1001 to get the gain and phase shift precisely at the frequency of 1000 Hz.
My practical measurement of gain does not match the transfer function:
The transfer function says: The gain at 10 Hz would be -0.00125 dB that means the ratio between the output voltage and input voltage is 0.999 but mine is 0.5959 !!
Vout and Vin are in volts.
Gain = Vout / Vin
dT is the phase shift in seconds.
Phase shift is in degrees.