question on BrainFlow gain change with ThinkPulse electrodes

jrseojrjrseojr Seoul, Korea
edited July 2021 in Cyton

Hi,
I get an issue regarding changing gain values of each electrode because of using ThinkPulse™ Active Electrode Kit.

Question: In order to use ThinkPulse™ Active Electrodes, I should set gain value as 8 or 5 by sending a command to a Cyton board. In that case, should I set value on certain variable or call some functions of BrainFlow? or do some extra calculations when I get data (e.g., "data = (board.get_board_data())[board.get_eeg_channels(0),:] * ???")?

P.S I am confusing that asking this question in this Forum is proper or not. If my question is not proper in this forum. I would like to apologize.

Thanks!

Comments

  • Andrey1994Andrey1994 Moscow

    you can multiply by 24 and divide by your new gain to get real value from the body

  • wjcroftwjcroft Mount Shasta, CA

    Hi, Jrseojr,

    I believe @Andrey1994 (BrainFlow developer) may have some insights into the warning you are seeing.

    You can also ask questions on the BrainFlow Slack, sign up via page below. But I think Andrey will see your question here on the Forum.

    https://brainflow.org/

    William

  • jrseojrjrseojr Seoul, Korea
    edited July 2021

    @wjcroft and @Andrey1994
    Thanks for answering.
    Ah... I have an additional question for the Cyton board and OpenBCI-GUI.
    As I mentioned above, I should use ThinkPulse™ Active Electrodes. Therefore, following the instruction of ThinkPluse, I set all electrodes' gain value as x8 in the hardware setting widget of OpenBCI-GUI.
    In that time, OpenBCI-GUI sent a command to Cyton board "x1040010X", "x2040010X", , , , "x8040010X".
    When I compare saved files (collecting EEG in x8 gain and x24 gain / same condition), all electrodes' uV values were different.

    Question for @wjcroft : If I only change gain value of electrodes in the Cyton board by sending the serial command (condition is using ThinkPulse electrode), I don't have to do anything on OpenBCI-GUI, and should I just use uV value of saved files without extra calculation?

    Question for @Andrey1994 : I have a question regarding your answer; however I will ask it on BrainFlow slack :).

    Cheers
    J.

  • wjcroftwjcroft Mount Shasta, CA

    Yes I believe if you change the gain in the GUI, the recording file always shows the correct microvolts.

  • wjcroftwjcroft Mount Shasta, CA

    Richard @retiutut, can you comment on the recording microvolts values when the gain is changed in the GUI?

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