HARDWARE - STIMULATORS









EEG AMPLIFIERS

One, two, four and eight channel amplifier units are available, which may be multiplied for larger channel arrays. All devices contain internal A-D converters and require only the USB cord to operate. Devices may be used with our data acquisition software, or analogue output is available for external A-D converters etc.

The one channel BioAmplifier and EEG8 units provide wide ranging control over gain and filtering, and are also suitable for other measures such as EMG, EOG, etc. The BioAmplifier is also available with a DC option. These amplifiers also include internal calibration and electrode impedance check facility.

EEG2 AND EEG4 AMPLIFIERS

These models use simplified filtering and gain ranges specifically selected for EEG. Analogue filters condition each independent, ultra low noise, high impedance differential amplifier, passing +/-5V signals to internal 16 bit A-D converters. Four available HP settings span from 0.01Hz to 1Hz, with an additional 30Hz, used as 'unblock'. Gain is selectable at 200uV or 400uV full sacle range, which are the settings we find most commonly used for EEG. Low pass filter may be configured at your preferred setting, normally 70Hz or 200Hz is used. The LP setting cannot be easily changed after manufacture.

These analogue signals are also available for external A-D converter connection if required. The unit only requires USB connection to function. In normal use, EEG flows to the PsychLab program on the host computer via USB. If used 'stand-alone' (i.e. without a host computer and utilising the analogue outputs), it will remember the last settings sent to it via USB. Adjustable High Pass frequency down to 0.01Hz is provided as with all our EEG range, making them particularly suitable for CNV and expectancy wave studies, where other 'DC' EEG amplifiers using digital filtering are less effective.

Units may be stacked / combined to produce larger numbers of synchronized channels and may be used in combination with any other devices in our range. A synchronization port is provided accomodate precise hardware event timing, for link up to other systems.

EEG4 SPECIFICATIONS
Maximum Signal Magnification
Nominal Output Voltage
Noise Level (Referred to Input)
Input Impedance
Low Frequency Response min (-3dB)
High Frequency Response max (-3dB)
Common Mode Rejection
Subject Isolation (optical / magnetic)
(Gain) 200,000
+/- 5V
<0.1uV
>1000Mohm
0.01Hz
see LPF
110dB
>5kV



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