CMS/DRL Sensor Set External (Flat or Pin, ActiveTwo)

This CMS/DRL External Sensor Set is specifically designed for use as external CMS/DRL with the ActiveTwo EEG system from BioSemi B.V. They can be used as ground and reference electrodes for EXG sensors or instead of the CMS/DRL in an A-Set. When used to replace the CMS/DRL of an A-Set, make sure CMS/DRL of the A-Set are hanging loose or else ground-loops are created.

CMS/DRL External Sensors come with a 160 cm cable which terminates in a 4-pin DIN type plug (plugs into AUX1 of the AD Box). CMS/DRL electrodes are available as either Pin or Flat type sensors.

One CMS/DRL External Sensor Set per pack.

Technical Specifications

• Electrode Type:
  • CMS (reference): Active Electrode
  • DRL (ground): Passive Electrode
• Electrode Form: Pin or Flat
• Cable Length: 160 cm
• Connector: DIN 4-Pin Plug
• Compatibility: ActiveTwo, BioSemi

Application Note

CMS (common mode sensor) is an active electrode sensor. DRL (driven right leg) is a passive electrode sensor. CMS and DRL electrodes create a feedback loop, which drives the average potential of the subject (the Common Mode voltage) as close as possible to the ADC reference voltage in the AD-box (the ADC reference can be considered as the amplifier "zero"). The return current is limited electronically at 50 uA. This protects the subject against excessive flow of currents due to amplifier and/or electrode defects. In addition, the circuit provides an indication (blue LED off) indicating whether such an error condition has occurred.

You cannot use both external CMS/DRL and CMS/DRL of the A-Set at the same time as this will create ground-loops.