Noise when electrodes are not attached.

huyuxinhuyuxin Singapore
edited May 2019 in Cyton
Hey there, I have just recently assembled my Cyton 8 Channel kit and I am receiving quite a large noise on channel 6 even when nothing is touching the electrodes.

image. 

The other channels seems to be ok though. This happens for connections with both the dongle and the wifi board. What can I do to resolve this?

Comments

  • wjcroftwjcroft Mount Shasta, CA
    Hi Huyuxin,

    What happens when you follow the tutorial instructions?


    Do the signals look ok there? In that tutorial the red lead (channel 7) is connected to 10-20 site O1. If channel 7 looks ok there (alpha can be seen with eyes closed), try moving the red lead over to channel 6. (And in the GUI, turn off 7 and turn on 6.) Do you get the same behavior with 6 as with 7?

    Depending on the noise in the environment, operating the Cyton with no leads connected to the pins can produce various types of 'RAILED' (maximums exceeded) results. The only sure way to assess a channel is when it is connected with wires: channel, SRB2 and Bias. (Or in the case of differential, plus and minus pins.)

    Can you also comment WHERE you purchased your OpenBCI? From our Shop?

    Thanks,

    William

  • huyuxinhuyuxin Singapore
    Followed the tutorial but can't seem to detect any alpha waves with eyes closed. No spikes around 10Hz was observed after my eyes are closed for 10s.
    When I moved the red lead over to channel 6, the signals on the app remained noisy.
    image
    Connecting channel 7's electrode wire (red) to channel 6's electrode seems to work fine, the electrode responds when touched and remained flat when not.
    image
    The SRB2 and Bias pins are connected to the provided earlobe clips, but not clipped to anything.

    And yes, the OpenBCI is purchased from the official shop.
  • huyuxinhuyuxin Singapore
    Here is a picture of the wiring
    image
  • wjcroftwjcroft Mount Shasta, CA
    Did you follow all the steps of the tutorial? How did the other tests work, ECG, EMG, EEG in general. This is important, please respond.

    You mention earlobe clips? Are you using gold cups and paste, or something else? If you have gold cups and paste, that is the best way to follow the tutorial.

    You say: "Connecting channel 7's electrode wire (red) to channel 6's electrode seems to work fine, the electrode responds when touched and remained flat when not." I'm not exactly clear what you are saying. That sentence would imply that channel 6 looks ok when connected to the red wire going to O1. Correct?

    Not everyone can generate the alpha with eyes closed. Besides O1 you could try P3 or P4 or Pz. Or try another subject. It's a bit hard to watch the GUI while checking for eyes closed alpha.

    You mention "alpha SPIKES", but it does not 'spike', it just gets somewhat larger on the FFT display. With subjects that demonstrate this, you can generally also see the modest ~ 10 Hz waveforms in the time series.

    For better GUI displays, turn off channels that are unused, not connected to skin.

    Regards,

  • wjcroftwjcroft Mount Shasta, CA
    I just see your Ultracortex setup. Do you have gold cups and paste?
  • wjcroftwjcroft Mount Shasta, CA
    "The SRB2 and Bias pins are connected to the provided earlobe clips, but not clipped to anything."

    Why are they not connected to your ear lobes??
  • huyuxinhuyuxin Singapore
    Sometimes it tends to spazz out and give wild readings on all channels too.

  • wjcroftwjcroft Mount Shasta, CA
    PLEASE PLEASE, go through all the steps of the tutorial with gold cups and paste if you have them.

    You have a huge amount of 50 Hz (mains) noise, is your notch filter turned on?

    Every time you move your head there is going to be moderate noise, that is just the nature of EEG.

  • wjcroftwjcroft Mount Shasta, CA
    In your video, I see that channel 6 is flat lining. Is it connected to your scalp? If so, then it looks like channel 6 is bad on your board. Does it respond at all or is it completely dead? Have you tried swapping the electrode holder / wire in channel 6 with other channels?
  • huyuxinhuyuxin Singapore
    Thank you for your response, I just got started on this EEG setup so I may mess some steps up in the process. Please bear with me if I have misinterpreted what you said. :D

    I do not have the gold cup electrodes and paste, so my tests with ECG, EMG can only be done with the provided spiky electrodes. 
    I have not being able to do those tests yet as it is pretty difficult to attach the spiky electrodes to my body, would you recommend getting the gold cup electrodes and paste for testing before continuing?

    Currently, I am using the provided earlobe clips in the ultracortex setup instead of gold cups and pastes.
    The statement "Connecting channel 7's electrode wire (red) to channel 6's electrode seems to work fine, the electrode responds when touched and remained flat when not." was meant to indicate that Channel 7 (originally connected to electrode at O1) looks alright when connecting to Channel 6's electrode placed at T6, indicating that the problem appears to not lie with the electrodes in Channel 6. Channel 6 on the OpenBCI Gui still contains a lot of noise and nothing I have done seem to resolve it, even unplugging the wires from the board.

    The channel 6 in the video is flat lining as I disabled it so that its noisy signal would not clutter the GUI. As of now, it is difficult to tell if channel 6 responds at all as the noise seems to drown out everything, giving me no indication when I touched the electrode. However, the other channels do respond when I touch channel 6's electrode. (Connected to yellow wire in the picture)
    In the video, the 50Hz notch filter is also turned on. 
    "Every time you move your head there is going to be moderate noise, that is just the nature of EEG." However, the video was taken with my head held pretty still, so I am a bit lost of what the issue might be. 

    "The SRB2 and Bias pins are connected to the provided earlobe clips, but not clipped to anything."
    Why are they not connected to your ear lobes?? This was before placing it on my head and I was checking if the connections were working fine by just touching the electrodes to see if there is a response in their channels. Hence the SRB2 and Bias are not yet connected to anything at the time.

    Thank you for your help William!
  • wjcroftwjcroft Mount Shasta, CA
    If you just purchased this and the channel 6 issue continues, then email contact at openbci.com, and ask how to proceed. Mentioning @openbci. 

    The tutorial is hard to perform without gold cups and paste. So you have no other electrodes besides the Ultracortex mounted ones?

  • huyuxinhuyuxin Singapore
    Yeap, only have electrodes from the Ultracortex mounted ones :/
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