Programmable Chip EEG

The Programmable Chip EEG is a dual channel electroencephalograph that could be a brain-computer interface.

The Programmable Chip EEG is programmable becouse of the Digitaly Programmable Potentiometers they are used to set the Gain, frequency range, and can calibrate multiple analog boards for different EEG tests.

The digital POT made by analog devices (AD5204) has 255 positions can be adjusted by the microcomputer that can receive commands from the computer. This is a great way for analog circuitry to have digital control. Digikey Part Number: AD5204BN10-ND

The AD5204 is a chip with 4 digitally controlled POTs and the pots can be daisy chained to have multiple chips controled by a single SPI interface.

The differential analog signal is amplified by the instramentation amplifier. Then the signal is amplified and conditioned by high pass and low pass filters.

The common mode signal is inverted summed and sent back to the body to decrese common mode signal thsi is done by the driver right leg circuit.

Band reject filters may be added soon in the future.

Then the analog signals are simultaniously digitized and the digital values can be clocked to the digital board.