1902 isolated pre-amplifier*

The 1902 is a versatile modular unit designed to work with modern computer-controlled data acquisition systems. Developed for a broad range of applications, the 1902 accepts biological and instrumentation signals from a wide variety of sources.

It is available in single or multi channel configurations. Communication with the computer is achieved through a serial line, allowing multiple sets of units to be controlled simultaneously.


  • Evoked response

  • TMS studies

  • Skin Conductance

  • Tremor Measurement

  • Auditory Brainstem

  • ...and many more life science and engineering research applications


A major advantage of programmable amplifiers is the degree of interaction between the signal conditioner and the application software recording the data. The 1902 is directly controlled through the CED data acquisition and analysis programs Spike2 and Signal, or through a stand-alone control application.

  • Trigger input converter from high-level pulses or switch closures to 5V TTL

  • Overload indicators with software readback

  • EMG filter with full wave rectifier and programmable post-filter gain

  • 16-bit ADC for digitisation of transducer and other low-bandwidth signals and transmission of results down the serial line

Software controllable features
  • Programmable gain with readback

  • Digital filters generated according to user-entered filter cut off values

  • Optional input clamping

  • Selectable mains notch filter

  • AC/DC coupling

  • Dynamically controlled 12-bit offset

1902 control panel

The isolated electrode input

The 1902 is designed to a specification worked out in conjunction with major UK physiological laboratories for an isolated amplifier to comply with EN 60601-1. It provides a low noise differential electrode input developed specifically for EEG, EMG, ECG and evoked potential applications.

IMPORTANT NOTE: The 1902 is research equipment and is not sold as a medical device within the meaning of the European Medical Devices Directive.

The transducer input port (non-isolated)

The transducer input port is suitable for use with a wide range of bridge and other transducers. It will accept single-ended and differential inputs and provides 5 volt and 12 volt outputs to supply the excitation voltages required by many transducers. Applications include: isometric force, strain gauges, temperature, pressure, acceleration, displacement and goniometers.

The 1902 is available in a transducer-only form with no isolated electrode input.

Technical Specifications
Main amplifier
Bandwidth DC to 10 kHz (-3dB) in DC mode 0.16 Hz to 10 kHz in AC mode
Gain accuracy ±2%

Filter response Bessel or Butterworth
Filter slope (low- and high-pass) 2nd or 3rd order (12 or 18 dB/octave)
Low pass filter corner frequency 1 Hz - 10 kHz cont. variable
High pass filter corner frequency 0.01 Hz - 1 kHz cont. variable
Filter latency 0.35 ms (approx.)
Rectification User-selectable

Mains notch cut (50 Hz or 60 Hz) 50 dB (typical)
Overload indicator 2 yellow LEDs (1 for each polarity) indicate when input is overrange
RS232 serial line 9600 Baud
USB via optional USB-serial adaptor
Important note: The CED 1902 is sold as a research instrument and not as a medical device within the meaning of the EC Medical Device Directive.
Transducer input
Input impedance 1 GOhm
Input bias current at 25 °C 50 nA
Common mode rejection (at x100 gain) 80 dB at 50 Hz
Bandwidth DC - 10 kHz
Gains x1 to x100,000
Gain step sequence 1, 3, 10
Gain accuracy ±2%
Noise 1 Hz to 10 KHz (at x100 gain) 1 microV r.m.s.
Power supplies & dimensions, single channel 1902
1902 chassis mechanical dimensions Width 240 x height 46 x depth 240 mm
1902 weight (approx.) 2.5 Kg
Power input 100 - 240V AC external power supply (PSU can supply up to four 1902s)
PSU weight 750g
Isolation pre-amplifier
Front end type Low noise EEG ECG
Input impedance
10 GOhm
Input bias current at 25°C
Noise referred to input, 1 Hz - 10 kHz
0.3 microV rms
Common-mode rejection at 50 Hz
100 dB
Common-mode voltage range
±1 V
Input offset voltage, initial adjusted
less than 10 microV after 1-hour warmup
Gain ranges (including 1902 system board)
100 - 100,000 or 1,000 - 1,000,000
Gain step sequence
1, 3, 10 ...
Gain accuracy
Bandwidth, all gains
DC - 10 kHz (-3 dB)
Isolation voltage, continuous
1500 V DC
Isolation voltage, peak for 5 sec
2500 V peak
Input-output leakage at 240V, 50 Hz
less than 20 microA
Input clamp option
0.5 - 14 ms
Lead configurations
I, II, III, aVR, aVL, aVF and V
1 mV pulse
Trigger inputs
Input impedance 100 kOhms
Voltage range ±15V
Trigger polarity Selectable
Trigger level +1.25 (approx.)
Trigger hysteresis +0.5V (approx.)
Output pulse TTL negative-going
Output pulse length 3 microSec
Trigger output drive capability 0.9 mA maximum

Items marked with* are investigational devices and for research use only. CAUTION - Investigational Device. Limited by Federal (or United States) law to investigational use.