TEC-B-01 User Manual
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version 1.1
page 16
Potential Electrode (BA-03X)
Set the ELECTRODE RESISTANCE (#
13
) switch to CURRENT ELECTRODE. The upper digital
display (#
10
) shows the resistance of the current electrode in XX.X M
.
Current Electrode (TEC-B-01)
Push the ELECTRODE RESISTANCE PUSHBUTTON (#
33
). The left digital display (#
3
) shows
the resistance of the potential electrode in XX.X M
.
Important
: Since the amplitude of the current pulses is relatively small (at least for oocytes) the
electrode resistance can be checked even if the electrode is inside the cell!
5.4. Capacity
Compensation
The frequency response of the potential electrode (low-pass characteristic due to stray capacities) is
compensated for by a feedback circuit ("negative capacity" compensation, CAPACITY
COMPENSATION) and a "driven-shield" arrangement (for an overview see Ogden 1994). Since
in
oocyte experiments
microelectrodes are usually in the one M
range or below for most experiments
it is
not required to use the CAPACITY COMPENSATION
.
The tuning of the capacity compensation control is performed using pulses applied to the COMMAND
INPUT or pulses provided by the electrode resistance test circuit. The TEC-B-01 has to be in CC mode
(see chapter 5.5).
With the cell model connected or the electrode in the bath the CAPACITY COMPENSATION control
is turned clockwise until there is no artifact on the POTENTIAL OUTPUT P
EL
.
Important
: Capacity compensation is based on positive feedback. Therefore overcompensation causes
oscillations which can damage the preparation or the recording electrodes. Therefore the control must
be handled with care and before impaling a new cell it must be set to 0.
