TEC-B-01 User Manual
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version 1.1
page 30
Since SERIES RESISTANCE COMPENSATION is done by positive feedback in the control circuit,
its use can lead very quickly to stability problems. Therefore, the clamp speed should be improved first
through conventional methods.
The optimal positioning of the electrodes, especially of the current electrode is important for best
SERIES RESISTANCE COMPENSATION (see also chapter 0). By placing the electrode in the center
of the oocyte, the membrane capacity is charged homogeneously. The capacitive current transient is
mono-exponential and the amplifier can be tuned without ringing around the slow tail of the transient
(Greeff, 2000).
Before the experiment make sure that the electrodes are in optimal position (see Figure 8). If
you have a micromanipulator that can remember positions you can first position the electrodes
without the oocyte. Then the position is saved and the electrodes are drawn back, the oocyte is
placed and the electrodes are brought back into the saved position.
Set the voltage clamp control mode switch to FAST.
Apply adequate test pulses without filtering.
Tune the amount of SERIES RESISTANCE COMPENSATION (#
13
), while watching the
current output. The capacitive transient of the current should show a mono-exponential decay.
Overcompensation is indicated by a ringing after the first peak of the capacitive transient (see
also Figure 7 in chapter 0, left side). This is also a sign that electrode position is not optimal.
