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ELC-03XS User Manual
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Figure 10: ELC x1 / x100 switchable headstage
Important: Even if the ELC-03XS is modified for the x1 / x100 switchable headstage it can
be used as a standard amplifier with a standard, i.e. not switchable headstage. In this case the
amplifier will recognize that a standard headstage is connected, and the additional current
switch at the front panel and the TTL input at the rear panel are automatically disabled.
8. Introduction into Experiments
The ELC-03XS is capable to perform several types of experiments that are briefly introduced
in the following with special focus on loose-patch stimulation and recording. It is assumed
that the capacity of the electrode is compensated, the offset of the electrode is cancelled and,
for intracellular recordings in BRIDGE mode, electrode artifact is eliminated using the bridge
balance circuit. Particularly, when working with charged substances and approaching the cell
in VC mode, the current offset is cancelled using the PIPETTE HOLD POTENTIAL
potentiometer (33, Figure 1).
8.1.
Recordings with the Differential Headstage (optional)
Extracellular measurements are mostly done in slices or in vivo, in noisy environments, where
distortions of the recorded signal caused by other instruments and the animal itself are very
common. Additionally, extracellular signals are very small and have to be amplified
enormously. The drawback is that noise is amplified as well. Therefore, the headstage of the
ELC 03X can be equipped with a differential input that minimizes noise pick-up. Differential
means, that the signal for the amplifier is the difference between the positive (+) (P
) and
EL
negative (-) (REF.) input of the headstage. This results in canceling of all common mode
signals (i.e. which both electrodes record, e.g. noise). For differential measurements, both
inputs of the headstage (REF. and P
) are connected to microelectrodes using cables with
EL
grounded enclosure or electrode holders. P
is connected to the measuring electrode and
EL
REF. to the reference electrode. The experimental chamber is grounded by an Ag-AgCl pellet
(or an AGAR bridge) connected to GND of the headstage (see Figure 11).
If differential measurement is not required (single-ended measurement configuration, see
Figure 11), the REF input must be connected to ground (GND). The amplifier is in an
undefined state, if the REF is left open, and can go into saturation making reliable
measurements impossible (for more details see Lalley et al., 1999).
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version 2.2
page 29
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