DC Preamplifier (NL102G)

DC Preamplifier (NL102G)

A direct-coupled pre-amplifier designed specifically for intracellular recording.

  • Electrode impedance checking
  • Four current injection ranges of ±100, ±50, ±20, and ±10 nA
  • Four bridge balance ranges of 100 MΩ, 200 MΩ, 500 MΩ, and 1000 MΩ
  • DC level control
  • Constant current capacitance compensation (neg. cap.)
  • x1 output amplifier has ±10 V dynamic input signal range
  • Low leakage current and low DC drift

Item# Description U.S. List Price Quantity
65-0222 NL102G DC Pre-Amplifier including Headstage and NL412 Pulse Generator
65-0223 NL102GH Replacement Headset (Including Fitting)
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The NL-102G DC Pre-Ampliflier is a suitable amplifier for intracellular recording. It can also be used for extracellular microelectrode recordings.

Used with the NL-106 AC/DC Amplifier, it provides a total gain up to x1000, while the NL-125/NL-126 filters provide continuously adjustable bandpass (and notch) filtering from DC to > 50 kHz. The NL-102G features capacitance neutralization, current injection (up to 100 nA) and impedance checking. Internally generated current injection and impedance checking can both be controlled by other devices or NeuroLog modules.

With features such as low leakage current and low DC drift, the NL-102G is particularly well suited for intracellular measurements through high impedance fluid-filled electrodes. The input stage is conveniently located at the end of a 2 meter cable for direct attachment to a micro electrode stepper.

The NL-102G now includes the NL-412 remote buzz box and NL-976 accessory kit. The NL-412 allows remote and full activation of the capacitance compensation circuitry. The buzz process can aid in cell penetration during electrode impalement.

Input Resistance 1011 Ω
Voltage Gains x1, x10 fixed
Input Voltage Range ± 10 V, absolute max. of ± 14 V
Gate Leakage Current Adjustable to zero
Rise Time Zero Source Resistance: 1 µsec
20 MΩ source resistance: 15 µsec
Injection Current Bridge Balance Selectable ranges: 100 nA/100 MΩ, 50 nA/200 MΩ, 20 nA/500 MΩ, and 10 nA/1000 MΩ
Zero Stability
(Referred to Input)
± 100 µV/day
Output Impedance 600 Ω
0 to 30 pF
Maximum Noise Level At 10 kHz Bandwidth Zero source input resistance: 20 µV peak-to-peak (4 µV RMS): 10 MΩ source resistance: 180 µV peak-to-peak (36 µV RMS)
DC Level Range ± 2 V (referred to input)
Output Voltage Range ± 11 V
Electrode Impedance Check
x1 out 1 mV/MΩ
x10 out 10 mV/MΩ
Calibrator 10 mV or 100 µV 150 Hz square wave
External Stimulus Input Range ± 10 V corresponds to ± full scale current depends on range selected
Amplification 2 Outputs Available:
x1 Out Voltage present at + input referred to GND including any potential dropped across electrode resistance by injection stimulus current applied. Max. voltage range of amplifier ±10 V.
x10 Out x10 signal present at + input referred to GND less voltage generated across electrode resistance Re when bridge balance control is correctly set for value of Re.
Bridge Balance Range ±10 V corresponds to 100 MΩ at 100 nA, 200 MΩ at 50 nA, 500 MΩ at 20 nA, and 1000 MΩ at 10 nA depending on setting of inject current selector (printed circuit board mounted)
DC Level Control Enables x10 amplifier to back off up to ± 2 V at input
Current Injection Stimulus currents can be injected into electrode system in either direction under following conditions:
1 Set by current inject control in magnitude, direction by front panel HYPER/DEP switch and gated ON or OFF by TTL gate pulses at front panel socket.
2 Set in magnitude and direction by analog voltage applied at front panel socket signal range ± 10 V; current injection can be combination of both control systems; full scale current injection conditions are printed circuit board selector at 100 nA, 50 nA, 20 nA or 10 nA
Out Socket
Allows connection of oscilloscope to monitor injection current (± 10 V full scale injection current)
Other Injection Current Possibilities
1 Max. uncontrolled current for dye injection to preparations or clearing of blocked electrodes; current is dependent on electrode resistance and can be up to ±1 µA max.; repeated reversal of selector switch usually cleans blocked electrodes
2 Impedance check measurement selected by front panel switch injects current (1 nA) through electrode giving signal at x1 output which is pulse wave of amplitude 1mV/MΩ or 10 mV/MΩ at x10 output
NL102G has front panel control to adjust amplifier section to compensate for capacity to ground at electrode; adjustment is easily made by switching on impedance check signal and setting NEG CAP control for fast rise time square wave without excessive overshoot at output; range is sufficient to compensate for capacities up to 30 pF; amplifier can be deliberately put into oscillatory mode by push button adjacent to NEG CAP control and is of use when penetrating cell membrane during electrode manipulation
Calibration Square wave calibration signal built into NL102G for calibration through complete system; select it through front panel switch as one of two magnitudes: 10 mV or 100 µV. Can be gate controlled by TTL signal applied to front panel sockets; signal (approx. 150 Hz) is summed with bridge balance signal at input of x10 amplifier section