The NL844 pre-amplifier is specifically designed to operate in conjunction with the NL820A Isolator. Its low noise and high impedance differential inputs make it particularly suitable for use as a headstage pre-amplifier close to the preparation, ideal for isolated EMG, EEG or ECG applications.
The NL844 features 4 pairs of colour coded 1.5mm DIN "touch proof" sockets for electrode connection as well as a COM input. The unit can be operated in 1, 2, 3 or 4 channel modes with unused channels switched off using the rear panel toggle switches.
This unit is particularly suited for use where there are very large stimulus artifacts, for example when used close to a magnetic stimulator coil. The input circuit automatically adjusts to the DC input conditions plus a non-linear filter modifies its time constant if the differential input signal exceeds its normal ± 0mV working range. Therefore, fast, short artifacts do not block the subsequent stages. This results in an amplifier with a very fast recovery time from stimulus artifact pulses.
|Gain||x100, x1,000, x10,000 (operated in channel pairs)|
|Low Frequency Cut||3, 10, 30 Hz (operated in channel pairs)|
|High Frequency Cut||With NL820A > 35 kHz -3dB|
|Input Impedance||100 MO|
|Common Mode||10,000:1 (-80 dB) (with NL820A -120 dB)|
|Noise||5 ¼V RMS full bandwidth|
|Lead Length||2.5 m|