There are nine gain ranges. In addition to the manual control, electronic operation of this facility is provided via the external computer control socket on the control panel. In addition to the manual control, electronic operation of this facility is provided via the external computer control socket on the control panel. Hz 100 uV square wave signal source, while the reference terminal is switched to 'isolated ground' potential. This simulates an electrode signal of 100 uV, which may be measured at the A-D converter for calibration purposes.
Calibration is selected simultaneously for all channels by a switch on the control unit.
The amplified output is passed to a level detection circuit which lights a tri-color LED for each channel on the front of the head amplifier unit, showing green for less than 5k ohms, orange for less than 10k ohms or red for greater than 10k ohms. These thresholds may be adjusted by a screw trimmer on the control panel. The AC current is fed to consecutive channels in opposite phase, such that the resulting current that flows through the ground electrode is minimised. For this reason, if the full compliment of 8 channels for each EEG8 unit is not used, try to balance the same number of both even and odd channel numbers. In addition to the manual control, electronic operation of this facility is provided via the external computer control socket on the control panel.