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I built my EEG circuit on a breadboard and wanted to see if it works

Question asked by Nilia on Feb 1, 2018

My simple EEG circuit is not working. For a simple test I built my EEG circuit on a breadboard and wanted to see if it works before adding filters and moving it to perfboard. I used an AD620AN and a TL082CN.

 

 

The gain is 50 * 50 * 50 = 125000. As alpha and beta wave amplitudes have a range of about from 10 uV to 40 uV, output should has a range of about from ±1.25V to ±5V.

Purple wires are connections to electrodes. There is also a voltage divider (R1 = 2k2 ohm and R2 = 1k ohm) connected to OUT/2 to decrease 0-18V to 0-5V. Voltage divider output is connected to an Arduino.

But the circuit is not working. There isn't even some noise on the output. Arduino is reading about 380 but no / very little movement. I even changed the AD620 and TL082 with new ones but it didn't work also.

It is really strange that this simple circuit doesn't work.

What can be "the problem"? I'm out of ideas.

Thanks in advance.

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