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GND provides system ground and is linked to the bath via an agar-bridge or a Ag-AgCl
pellet. The headstage is attached to the amplifier with the headstage cable and an 8-pole
connector. The headstage can be mounted directly to a micromanipulator using the mounting
plate, a dove tail or a holding bar.
Important: The shield of the BNC connector is linked to the driven shield output and must not
be connected to ground. The headstage enclosure is grounded.
Caution: Please always adhere to the appropriate safety precautions (see chapter 1). Please
turn power off when connecting or disconnecting the headstage from the HEADSTAGE
connector!
7.2.
Headstage Bias Current Adjustment
Caution: It is important that this tuning procedure is performed ONLY after a warm-up
period of at least 30 minutes!
The ELC-03XS is equipped with a voltage-to-current converter with a very high output
impedance which is connected to the recording electrode. The zero current of this unit is
tuned with the BIAS current potentiometer (#49, Figure 1).
The tuning procedure should be performed regularly (at least once a month) since the BIAS
current changes over time.
The tuning procedure is performed using high-value resistors and/or a cell model. It cannot be
performed with an electrode, since there are always unknown potentials involved (tip
potential, junction potentials).
Disconnected all input signals (except the headstage). Put the CURRENT (nA) switch
(10, Figure 1) to position 0. Set the operation mode to CC.
Set the BIAS control potentiometer to 5 (zero position).
Connect the P
connector of the headstage to ground.
EL
Note: This cannot be done with the cell model. Please use a wire to connect the input of
the BNC connector on the headstage to GND of the headstage. Do not use the shield of
the BNC connector since it is connected to driven shield.
Tune the OFFSET to zero using the OFFSET control.
Remember: The zero position of the OFFSET control is at 5!!
Remove the wire and attach the cell model or a resistor with a value of about 5 M across
the same connection.
The value displayed at the POTENTIAL DISPLAY is related to the BIAS current of the
headstage according to Ohm's Law. Cancel this voltage by tuning the headstage BIAS
current potentiometer until the POTENTIAL DISPLAY shows 000.
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version 2.2
ELC-03XS User Manual
page 27
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