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INSTRUMENT OPERATION
Axopatch 200B, Copyright 1997-1999, Axon Instruments, Inc.
EXTERNAL COMMAND INPUT (front panel switched)
Applies external command signal divided by 50 to the command input of the
Axopatch 200B when the front toggle switch is set to EXT. COMMAND.
EXTERNAL COMMAND INPUT (rear panel switched)
Applies external command signal divided by 10 to the command input when the rear panel
switch is engaged. This input should be used for VOLTAMMETRY commands, since the
10-fold scaling factor allows for the greater voltage range required for such experiments
(up to ± 1 V).
The two external command inputs are summed together inside the patch clamp.
FORCED RESET INPUT
Causes the integrator and differentiator to reset on the positive edge of a TTL pulse. Used,
for example, to force a reset just before applying a command to a cell or membrane patch.
This increases the probability that no reset will occur during the brief recording period
following the command.
SPEED TEST INPUT
When switched on by the rear panel switch, the SPEED TEST injects a current into the
headstage input through a 1 pF capacitor in the headstage. This is used for verifying the
dynamic response of the headstage. Injected current waveform is the derivative of the
voltage waveform applied at SPEED TEST input. For example, a 100 Hz 10 V
p-p
triangle
wave will inject a 1 nA
p-p
square wave into the headstage input.
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