Use this 1.5 mm AC-coupled electrode lead adapter when more than one ground is required while recording electrodermal activity (i.e., Galvanic Skin Response). One end of the adapter plugs into the ground on the amplifier and the other end accepts the electrode lead.
To record GSR with other biopotential signals (ECG, EEG, EOG, EGG, EMG, ERS), BIOPAC recommends using CBL205 connected to one ground on any of the biopotential amplifiers. The subject will be grounded through the Vin- of the GSR electrodes, but in some cases it is necessary to have more than one ground; in such cases, use an AC-coupled lead adapter (CBL205) to prevent ground loops.
For example, if—while recording a biopotential and GSR— the GSR electrode is removed during a stage of the experiment, you will want to maintain ground for the biopotential. To always have a ground and no ground loops:
Connect the Vin- lead of the GSR as ground.
Connect an AC-coupled ground to the biopotential amplifier.
Note—If using any two of the following at the same time: GSR100C, EBI100C or the NICO100C, ground loops will be a problem and you will not be able to make absolute measurements (such as SCL). One solution is to record with two MP150 systems, with one of the two units connected to each system.
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