TEC-B-01 User Manual
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version 1.1
page 15
5.2.
Offset Compensation
If an electrode is immersed into the bath solution an offset voltage will appear, even if no current is
passed. This offset potential is the sum of various effects at the tip of the electrode filled with
electrolyte (“tip potential”, junction potential etc.). This offset voltage must be compensated i.e. set to
0 carefully with the OFFSET controls (#
11
at TEC-01B and
#
16
at BA-03X) before recording from a
cell. The OFFSET compensation is done in CC mode of the amplifier. When adjusting the OFFSETs
make sure that no current flows through the electrodes. Thus, it is recommended to disconnect
COMMAND INPUT (#
15
) and to disable the HOLD
unit (switch #
7
to 0).
Potential Electrode
The potential of the potential electrode is read from the POTENTIAL DISPLAY (#
3
) of BA-03X.
The display shows the potential of the potential electrode in XXX mV.
Compensate the OFFSET with the OFFSET (#
16
) potentiometer from the BA-03X.
Current Electrode
Switch the reading of the TEC-B-01 digital display (#
9
) to V
CEL
using the electrode selector switch
(#
10
). The display (#
9
) shows the potential of the current electrode in XXX mV.
Compensate the OFFSET with the CURRENT ELECTRODE OFFSET (#
11
) potentiometer.
Note
: If a cell model is connected the OFFSET controls should read values around 5, otherwise it is
likely that the headstages or the amplifier are damaged. If microelectrodes are used unusual high
OFFSETs are a sign of badly chlorinated silver wires or unwanted grounding of the bath.
5.3.
Electrode Resistance Test
The electrode resistance is dependent on the tip diameter of the electrodes and may reveal whether
electrodes are broken or clogged. Therefore, a resistance measurement test for the CURRENT
ELECTRODE microelectrodes is included in the TEC-B-01. The respective test for the POTENTIAL
ELECTRODE is included in the BA-03X. The test operates independently of any other adjustments,
assuming that all microelectrodes are in contact with a grounded bath (zero potential). The measured
resistance is independent of tip potentials and is automatically displayed on the respective digital
display in M
. Furthermore, the electrode resistance can be tested even if the electrode is inside a cell!
The measurement is performed by applying square current pulses of ±10 nA to the respective
microelectrode. The voltage deflection caused by this injection is recorded and processed to give a
direct reading in M
on the digital display.
Important
: The electrode resistance test is also a test of the correct function of the respective
headstage.
The resistance test gives only a rough estimate of the electrode resistance. The value for the current
electrode is dependent on the calibration of the current headstage (see chapter 5) and the reading is
correct only in position x1.
