The NL144 FILTER is a 4-channel, second order (two-pole) high-pass filter module. It is an ideal partner for the NL820A Isolated Amplifier system with its 4-channel NL844 AC pre-amplifier and the NL530 4-channel Conditioner module. In combination with either the NL135/136 or NL134 Filters, a full 4 channel low frequency and high frequency cut-off system is provided.
The filter settings have been selected for most electrophysiological and human neurophysiological protocols but other frequencies can be factory set to order. The design is implemented using low noise active linear circuitry and does not suffer any of the aliasing problems that are encountered when cheaper methods are used. A rotary switch selects the 14 frequency settings giving repeatability over a wide range with 12dB/octave [40dB/decade] attenuation below the selected frequency value. The ‘DC’ switch position by-passes the filter sections completely.
Rear connections to the motherboard allow Input and Output interconnections between this and (newer) NL820A, NL134/135/136 and NL530 modules without the need of front panel cables.