Neurolog Filter & Conditioner Modules

The NL125/6 filter module employs two active sections to control the high and low pass characteristics. The low frequency cutoff point can be set continuously from 0.5Hz to 5kHz with a single turn potentiometer, in four switched ranges. Similarly the high frequency cutoff can be set continuously from 5Hz to 50kHz in four switched ranges. DC and WB (wide band) switch positions by-pass the lower and upper filter sections, respectively. A switchable active notch filter is provided for the rejection of line frequency interference; this can be set by the user to 50Hz or 60Hz, with a 20Hz notch width (-3dB points).

The NL134/5/6 FILTERS are 4-channel, second order (two-pole) low-pass with mains frequency Notch reject (NL135/6 only) filter modules. They are ideal partners for the NL820 Isolated Amplifier system.The filter settings have been selected for most electrophysiological protocols but other frequencies can be factory set to order.A rotary switch selects the 14 frequency settings giving repeatability over a wide range with 12dB/octave [40dB/decade] attenuation above the selected frequency value. The ‘WB’ (wide-band) switch position by-passes the filter sections completely (both LP and Notch). The active Notch filter provides rejection of line frequency [50Hz (NL135) or 60Hz (NL136)] interference when switched in. (No switch is fitted on the NL134).

The NL143 is a 3-channel difference, or differential, amplifier with 4-channels of input. Internal selection allows the difference between any of the four input channels to be made. Internal preset controls (finger operated) allow an offset to be nulled or added as required.High input protection allows for signals coming from units that are not part of the NeuroLog System.This module allows the difference between two signals of interest to be continuously monitored, but can also be used to null DC offsets introduced by computer DAC interface cards.

The NL144 is a 4-channel, second order (two-pole) high pass filter which complements the NL134/5/6 mentioned above.when used with the NL820A isolator, these module provide a compact solution to 4 channel high and low pass filtering.

A single width module designed to give gain and offset set-up controls when interfacing signals to the analog-to-digital converters (ADCs) of PCs.The module contains four channels each with independently adjustable filter settings and front panel gain and offset presets. There is also a master ADC offset control to allow unipolar ADCs to be used with bipolar signals.As ADC boards have a precise input range (outside of which damage may occur) the module features on-board preset controls to set all channels to ‘CLIP’ (or limit) at independently set positive and negative (or zero) levels.