ELC-01MX User Manual
version 2.6
page 12
(2) PIP. HOLD / OFFSET potentiometer
Control to compensate for the electrode potential OFFSET (ten-turn potentiometer,
symmetrical, i.e. 0 mV = 5 on the dial) in CC mode (range:
±
100 mV), or to zero the pipette
current in VC mode.
In CC mode any offset caused by electrode (tip potential, liquid junction potential etc.) is
cancelled by subtracting this potential value from the electrode, i.e. an offset of –10 mV is
cancelled by subtracting -10 mV using this potentiometer.
In VC mode an offset at the electrode would lead to current flow through the electrode
because without a COMMAND the electrode will be clamped to 0 mV, and the VC circuit
generates a current to achieve this. In order to avoid this current flow the electrode has to be
clamped to its offset potential, i.e. a potential has to be added to the COMMAND. In the
scenario mentioned above the electrode has to be clamped to –10 mV. Then, the electrode is
clamped to its offset potential and no current will flow.
If the OFFSET is correctly compensated in CC mode, there is automatically no current flow
when approaching the cell in VC mode. However, liquid junction potentials occurring after
establishing the whole-cell configuration are not automatically cancelled.
Important: Command potentials are not affected. Potential out shows zero!
Note: This procedure has to be done at the beginning of the experiment as soon as the pipette
has contact to the bath solution, i.e. before approaching a cell.
(3) CUR. OUTP. SENSITIVITY switch
Switch to select the scaling of the CURRENT OUTPUT
0.1
0.1 V/nA (1 V = 10 nA)
1
1 V/nA (1V = 1 nA)
10
10 V/nA (1 V = 0.1 nA)
(4) HOLD. CUR. (nA) potentiometer
Ten-turn potentiometer for generating a holding current in CC or BRIDGE mode, or for
setting the amplitude of the GATED stimulus (see also #9), range:
±
100 nA (100 = 10 nA).
(5) HOLD. CUR. (nA) polarity switch
Switch for setting the polarity of the holding current in CC or BRIDGE mode, or for the
GATED stimulus (see also #9). In zero position the holding current/gated stimulus is disabled.
(6) C.COMP. potentiometer
Ten-turn potentiometer for compensating the capacity of the electrode, clockwise, range:
0-30 pF. Functional in all current clamp modes (CC, CC+ BRIDGE, R
EL
, OFF)
(7) STIM. INPUT 10 nA/V connector
BNC connector for an external command in CC or BRIDGE mode (sensitivity: 10 nA / V, i.e.
1 V = 10 nA).
The voltage signal that is connected here is transformed to a proportional current at the
electrode in CC mode. The signal form remains unchanged.
