Circuit Detail: The “Electrode Check” circuit injects a low current 30 Hz sine wave into the “+” and “-” connectors of the SS1LA or SS2L leads.
The circuit is able to measure the Voltage Peak to Peak (V P-P) between “+” and the Ground electrode, as well as between “-” and the Ground electrode. The voltage will vary depending on the resistance between the electrodes. The more resistance, the more the voltage measured.
The circuit is also able to temporarily remove the input connections, in order to determine the voltage in a high impedance state. This allows an auto calibration to be performed without requiring the user to remove the cable from the “Electrode Check” connector.
The calculated resistance (calculated by the hardware/software/firmware) is displayed on the screen when you choose MP3X menu > Electrode Checker.
If the “Check Electrode Impedance” button is not displayed in BSL EEG Lessons (L03 and L04), you will need a free hardware update to restore functionality.
Under severe cases of electrostatic discharge, the Electrode Check on older MP35 or MP36 models (2012 or earlier) could potentially lead to hardware damage. The system will withstand extreme amounts of static discharge and exceeds all of the current standards. To prevent potential damage to these older MP35 or MP36 DAQ units, EEG lessons were updated to disable the “Check Impedance” button in BSL EEG Lessons. BIOPAC is offering a free Electrode Check hardware upgrade to enhance the performance of the system. After the upgrade, the Electrode Check will be enabled in EEG Lessons 3 and 4.
We strongly recommend this upgrade if you use the Electrode Check feature.