HEKA Elektronik EPC 10 USB, Руководство по оборудованию, Страница: 41 / 81

5.1 EPC 10 USB Window 35
CC-Gain: Four current clamp scaling ranges can be selected:
ˆ
0.1 pA/mV
ˆ
1 pA/mV
ˆ
10 pA/mV
ˆ
100 pA/mV
Figure 5.18: CC-Gain
These correspond to maximum command currents of 1 nA, 10 nA, 100 nA and 1 µ A, respectively. This scaling has
to be taken into account, if one intends to use the ”External Stim.Input CC” for stimulation. When the CC-scaling
is set to 1 pA/mV, a 100 mV command, feed into ”External Stim.Input CC”, would result in 100 pA command
current.
Note: The maximum command currents can be increased by a factor of ”5” when activating the
Extended Stimulus Range
in the
EPC 10 USB
menu.
Note: The Gain settings are restricted to the selected range, i.e. with a CC scaling of 1.0 pA/mV,
only the intermediate Gain range (0.5-20 mV/pA) can be used in current clamp mode.
Gentle CC-Switch: This control selects between the two alternate modes of switching back and forth between
voltage and current clamp. When selecting Gentle CC-Switch: On , I-hold will be set to inject the holding current
required to keep the membrane voltage constant while switching to current clamp mode. Thus, V-mon will be
identical to the original V-membrane commanded under voltage clamp. In analogy, upon returning to voltage
clamp, V-membrane will be set according to the membrane potential under current clamp and rounded to the next
2 mV. When selecting Gentle CC-Switch: Off , I-hold will be set to 0 pA when switching to current clamp mode.
Figure 5.19: Gentle Switch
V-mon Gain: The measured voltage can be amplified by a factor of 10 or 100 before digitization. In the Vmon*100
setting the voltage range is 100 mV instead of 1 V, therefore the resolution is 10x better. This is particularly useful
in field potential measurements, where small voltage deflections are to be resolved.
Note: This feature is available only with
EPC 10 USB
revision F (or newer) amplifiers.
Figure 5.20: Vmon Gain
Last V-memb: Quite often, the membrane potential under current clamp will have changed, and when returning
to voltage clamp, V-membrane will possibly differ from that set before switching to current clamp mode. Last
V-memb can then be used to conveniently restore the original V-membrane value.
Figure 5.21: Various controls
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