Hello all, I am a computer and electrical engineering student and I am doing a project where I am making an EEG. I used a design that I found here: https://hackaday.io/project/167393-low-cost-eeg-circuit. I have checked the circuit that we made on a breadboard several times and everything is connected properly. As I tested from stage to stage I found that after the lowpass filter in the bandpass filter, the first 1uF capacitor seems to discharge down to zero. So after that stage, like the output of the variable amplifier, there is no output voltage. Any possible solutions?