| The
Model 2400 is a low noise, full featured intracellular/extracellular
amplifier designed for voltage clamping using patch electrodes
on single channels or whole cells. Its unique design allows
fast intracellular current clamp measurements with sharp electrodes.
Advanced circuit design techniques using field programmable
gate arrays eliminated noisy microprocessors.
Amplifier current gain is extremely flexible as it can
accept any of four resistive feedback probes. Each probe
has two feedback resistors selected from the following values:
10MΩ, 50MΩ, 100MΩ, 1GΩ, 5GΩ, and
10GΩ. The wide range of feedback resistors means currents
can be recorded with outputs of 1mV/nA to 10mV/fA. The standard
probe sent with each unit is the 100MΩ / 10GΩ version,
but other values can be selected.
Unlike other patch clamp amplifiers, the Model 2400 has a voltage follower
in the probe. This allows this amplifier to be a true fast current clamp
amplifier with no instability. An integrated four
pole low pass Bessel filter provides flexible signal conditioning. Fine
tuning capacity compensation is available to eliminate virtually all
electrode-induced transients. Calibrated whole cell compensation
provide
easy display of membrane capacitance and access resistance.
A host of command potentials are integrated internally within the model
2400, including an automatic tracking command to zero the membrane current,
manual controls for offset and holding potentials, and an easily readable
digital display. For signals that are more complicated, an external command
input with different scaling factors is available for use with any signal
source
A digital meter provides accurate values of command signals and membrane
currents or voltages, the true RMS noise of the amplifier and experimental
setup, the cut off frequency of the low pass filter, and the overall gain
of the amplifier plus probe.
Series resistance compensation provides the researcher with the option
of introducing either or both predictive and corrective compensation from
zero to 100%. Fine and coarse controls for lag provide sensitive control
to minimize oscillation produced by compensation close to 100%.
Separate compensation controls exist for eliminating transients seen
during current clamp experiments when the bridge balance is used.
Telegraph outputs provide analog voltage equivalents of front panel
settings including error conditions, amplifier mode and gain, Cmembrane,
RMS noise, and low pass filter cut-off value. These telegraphs
allow the Model 2400's front panel settings to be automatically recorded
by your system software.
For those who need extra large bandwidths, the raw bandwidth of the entire
amplifier may be adjusted via a rear panel potentiometer.
A second powered probe input is available for use as a bath signal input. |