Hello, human. I bring to your attention a small report on the two-channel EEG amplifier board designing.
Compared with the simulated circuit diagram (see previous post), I used trimming resistors in the input gain control circuit (instrumentation amplifier). Thus, it is possible to calibrate the amplifier for measurement with high accuracy, or to change the range of the measured signals. The input bus line supports working with active electrodes, for which the power bus line is connected. To shield the circuit nodes, the entire board will be hidden from both sides by metal covers (see next post). Since the area of the intended application of the board is a mobile system, the board size was reduced as much as possible, and amounted to 26.5mm * 34.8mm. The height of the board will be determined after the end of the protective covers design. Below you can see a diagram and a drawing of some layers of the printed circuit board, also I made a couple of 3D board models.