Low Pass & High Pass Filters (NL134, NL135, NL136, NL144)

Low Pass & High Pass Filters (NL134, NL135, NL136, NL144)

Various low and high pass filters.

  • Four-channel two-pole filters
  • With and without notch
  • 50 and 60 Hz notch available
  • Low and high pass filter options

Item# Description U.S. List Price Quantity
65-0239 NL134 4-Channel Low Pass Filter, without Notch Filter
65-0240 NL135 4-Channel Low Pass Filter, with 50 Hz Notch Filter
65-0241 NL136 4-Channel Low Pass Filter, with 60 Hz Notch Filter
65-0242 NL144 4-Channel High Pass Filter, without Notch Filter*
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The NL134, NL135 and NL136 are 4-channel, 2-pole (second order) low pass filters. Both the NL135 and NL136 have an AC power rejection notch filter module that is an ideal partner for the NL820A Isolated Amplifier System with its 2/4 channel AC or DC pre-amplifiers.

The filter settings have been selected for most electrophysiological and clinical 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 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 NL144 is a high-pass version and does not have a notch filter. Preset factory filter settings span from 0.1 to 200 Hz in 1-2-3-5 steps.

Input Voltage Range ± 15 V max, ± 10 V operating
Input Impedance 120 kO
Filter Settings (-6 dB) 10 to 20k Hz in 1-2-3-5 steps, and WB
Cut-Off Accuracy (± 2% ±1.25 Hz < 630 Hz) or
(± 2% ± 62.5 Hz > 630 Hz)
Gain Before Cut-Off +1.0
Attn. Beyond Cut-Off 40 dB/decade, 12 dB/octave
Notch Attn/Width (-3 dB) > 50 dB/20 Hz
Crosstalk // Noise Better than -60 dB // < 100 µVrms