BA-01X User Manual
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version 1.9
page 21
7. Test and Tuning Procedures
Important: The BA-01X should be used only in warmed-up condition, i.e. 20 to 30 minutes
after turning power on.
The following test and tuning procedures are necessary for optimal recordings. It is
recommended to first connect a cell model to the amplifier to perform some basic adjustments
and to get familiar with these procedures. It is assumed that all connections are built as
described in chapter 5.
Important: Except for Headstage bias current adjustment (see 7.1) all adjustments described
below should be carried out every time before starting an experiment or after changing the
electrode.
7.1.
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 BA-01X system 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 control (#13, Figure 1, chapter 3.2).
The tuning procedure must be performed regularly (about once a month) since the bias current
changes over time. If very small currents are used (in the 10 pA range) the procedure must be
repeated in shorter intervals.
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).
o
Disconnected all input signals (except the headstage). Put the holding current switch to
position 0 (+ / 0 / - switch, #12, Figure 1).
o
Connect the MICROELECTRODE connector of the headstage to ground. If parasitic
oscillations occur use a 10 k
Ω
resistor for grounding. If you use a cell model set #3 in
Figure 7 to GROUND.
Note: 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.
o
Tune the OFFSET to zero using the OFFSET control (#16, Figure 1, see also chapter 7.2).
o
After tuning the OFFSET connect the cell model via the SUBCLICK connector (sharp
electrode). If you do not use a cell model, remove the wire and attach a resistor with a
value of about 5 to 10 M
Ω
across the same connection.
o
The value displayed at the DISPLAY (#2, Figure 1) is related to the BIAS current of the
headstage according to Ohm's Law. Cancel this voltage by tuning the headstage BIAS
current potentiometer (#13, Figure 1).
