TEC-B-01 User Manual
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version 1.1
page 19
General Considerations
The key to accurate and fast recording is a properly built setup.
Make sure that the internal system ground is connected to only one point on the measuring
ground and originates from the potential headstage. Multiple grounding should be avoided; all
ground points should originate from a central point. The electrode used for grounding the bath
should have a low resistance so that it can pass large currents.
Use electrodes with resistances as low as possible.
Keep cables short.
Check regularly whether cables and / or connections are broken.
Make sure that chloriding of silver wires for the electrodes is proper and that there are no
unwanted earth bridges, e.g. salt bridges originating from experimental solutions.
Only if no intracellular series resistance is considered TEC system can be tuned according to one of
three optimization methods (see also chapter 9):
1.
the “linear optimum” (LO) that provides only slow response to a command step and a maximal
accuracy of 90-97%.
2.
the "absolute value optimum" (AVO) that provides the fastest response to a command step with
very little overshoot (maximum 4%) or
3.
the "symmetrical optimum" (SO) has the best performance compensating intrinsic disturbance
signals but shows a considerable overshoot (maximum 43%) to a step command.
Under consideration of an existing intracellular series resistance these methods cannot be applied.
Instead, a series resistance compensation can be introduced to optimize clamp performance (see also
chapter 9.2).
Three control modes are implemented to adapt the TEC-03X to the needs of the user:
1.
NORMAL fits to many users. In this mode a good compromise between speed, accuracy,
noise and stability is achieved. The normal mode can be optimized by the LO
method (see above).
2.
SLOW
for relative slow recordings (e.g. ligand activated currents). In this mode accuracy
and stability are increased while speed is decreased. Optimization is done
according to the AVO- or SO method (see above).
3.
FAST
for very fast recordings (e.g. fast voltage activated currents). In this mode speed
and accuracy are increased but the system is very sensitive with a higher noise
level and tuning requires more experience. Optimization is done by adjusting the
amount of current proportional gain of the SERIES RESISTANCE
COMPENSATION and optimal positioning of the electrodes (see chapter 0).
Important
: First use a cell model for the tuning procedure. You will get familiar with the different
settings and the consequences for the system without any damage to cells or electrodes.
