Electrode cap, all channels are railed [resolved]

hvrigazovhvrigazov Sofia, Bulgaria
edited July 20 in Electrodes

Hello, I have an Electrode Cap. I followed these steps:
https://docs.openbci.com/docs/04AddOns/01-Headwear/ElectrodeCap
Now, when I try to use the EEG, I see "Railed" on every channel and very high values for each channel. I am not sure if it's working at all. It does not look anything like the examples. I have attached a recording. Beware that I have no experience with EEG devices so I just followed all instructions blindly.

Comments

  • wjcroftwjcroft Mount Shasta, CA

    HVrigasov, hi.

    Are you using Cyton? Has it worked correctly in the past with other electrode setups? Have you checked your reference and ground connections? If all channels are railing, it usually means a bad connection which all channels share.

    William

  • hvrigazovhvrigazov Sofia, Bulgaria

    Hi, I am using CytonDaisy. It has never worked before, I tried 4-5 times before in the past 6 months, same thing happens everytime, I have never been able to get useful data from it so far. Maybe I am wiring something wrong (as I said, I have no experience at all, so probably I am doing something really stupid). For example, in the following instruction:

    "Connect bottom pins N1P through N8P on the Cyton to a set of HPTA cables, shown below. These pins will be channels 1-8 on the OpenBCI GUI."

    Does it matter which pins I am connecting to which HPTA cables? Because I am selecting them at random. I can send pictures and tell you exactly what I have connected later today or tomorrow if it will help.

  • wjcroftwjcroft Mount Shasta, CA

    HVrigasov, hi.

    It has never worked before, I tried 4-5 times before in the past 6 months, same thing happens everytime, I have never been able to get useful data from it so far.

    So did you ever try reaching out to OpenBCI tech support via email (contact at openbci.com)? Normally a customer would expect to verify operation of his new product in a timely fashion. New products have a warranty period.

    From the descriptions you have given, it seems highly likely that your REF (reference) leads, connections, contacts, or gelling on the cap, are insufficient to make a valid quality scalp connection of the reference point on the cap. Without a reference, the 8 or 16 channel pins just 'float' and collect random noise, causing the 'RAILED' state you see.

    Have you followed the instructions in the document for connecting the REF and BIAS correctly? Do you have access to a digital voltmeter to check continuity (close to zero ohms) of the connection from the Cyton SRB2 pin ('bottom' SRB pins) to your electrode on the cap labeled 'REF'?

    Are you sure you are gelling the electrodes correctly? Too little or too much gel can cause issues. Do you have access in your network, school, company, to anyone with prior EEG experience?

    William

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