Reference Section • 79
Chapter 5
External Command Inputs
• External command stimuli are applied to the COMMAND BNC on the front panel
of the MultiClamp 700A.
• External Command Sensitivity is set in the Gains tab under the Options button
(
).
• Command Filter Frequency is set in the General tab under
.
• See also Capacitance Compensation, Feedback Resistor, Filter, and Mode.
Although the MultiClamp Commander provides some simple built-in command stimuli
(e.g. via the Pulse button), it is expected that most experiments will require more
complex stimulus protocols. These must be supplied by an external pulse generator or
a computer program like pCLAMP. External stimulus commands are supplied to the
MultiClamp 700A via the COMMAND BNC on the front panel (one BNC for each
Channel). Note that this is a DC-coupled input, so be sure that the external pulse
generator is correctly calibrated so that zero volts really correspond to zero.
External Command Sensitivity
External Command Sensitivity is a scaling parameter that is set in the Gains tab under
the Options button.
In V-Clamp mode, the purpose of External Command Sensitivity is to scale down the
command signal in order to reduce the effect of noise in the external pulse generator.
There are three settings: 20 mV/V, 100 mV/V and OFF. For example, 20 mV/V means
that a 1 Volt step applied to the COMMAND BNC will appear to the cell as a 20 mV
step; i.e. external commands are divided down by 50-fold. This setting should be used
when you wish to minimize noise as much as possible. The 100 mV/V setting (10-fold
dividing down) should be used when you wish to apply larger command stimuli to the
cell and noise is less of a concern.
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