Noise and huge offset with Cyton and new gold cup electrodes [resolved]
iswapneel
Bangalore, India
I have recently got Cyton Board from a friend and while trying a tutorial from
https://docs.openbci.com/docs/01GettingStarted/02-Biosensing-Setups/EEGSetup
Signal I got on GUI was noisy and with huge offset. I tried couple of experiments
1. Short Channel 1 + SRB2 + Bias : EEG signal Range 4000uV+
2. Short Channel 1 + SRB2 with bias left dangled : EEG signal range ~10uV
I have uploaded photos of GUI and board setup here
https://drive.google.com/drive/folders/1lxzXB4JnN5DRvpIsIuO8Vo6q8sTu7Vif?usp=sharing
I was expecting signal to be in range of 20uV but I am getting signal in range of 10000uV+ in experiment 1. I tried with another channel and got around 4000uV+ signal. I am not sure what is the issue with the setup.
Would really appreciate any help.
Comments
Swapneel, hi.
When was this board purchased? Did it EVER work correctly, for example, with your friend?
Shorting all three electrodes: channel, SRB2, and Bias, SHOULD result in close to zero microvolts. If that is not happening, then something is wrong. Have you tried swapping some of your electrodes around? A gold cup electrode, if chipped, will expose the tin metal underneath, creating a battery effect. Are these gold cups from OpenBCI? What paste are you using?
Regards, William
Hi William,
Thanks for your reply ! Electrode are from OpenBCI and they have arrived a week ago.
I tried few more experiments and found that culprit was the bad conductive paste. With exact same setup and with new conductive paste (Ten 20 ) I am getting expected EEG signal.
Cheers,
Swapneel