BC-535 Preliminary, Rev. 060126
20
•
Deactivate the
OFFSET CONTROLS
by moving the
UNLOCK
toggle to the unlock position. The
ACTIVE
LED will go off and the toggle will return to its original position. The offset reading on
the
METER
in the
METER
block will not change.
•
Adjust the position of the trace on the oscilloscope to a convenient reference line.
•
Switch the
SELECTOR
SWITCH
in the
METER
block to
Σ
V
c
.
•
Using the
VOLTAGE
UP
/
DOWN
TOGGLE
switches in the
HOLD
block, adjust hold potential until
the meter reads 20 mV.
•
Switch the
COMMANDS APPLIED
toggle in the
HOLD
block to on. The
COMMANDS APPLIED
LED will
light.
•
Notice that the displayed voltage on the oscilloscope moves from zero to 0.2 V (one division
upward).
•
Notice that the
METER
also shows 20 mV. This reading is correct since the V
c
X
10
OUTPUT
is the
applied V
m
HOLD
multiplied by 10 (e.g.: 20 mV x 10 = 0.2 V).
•
Switch the amplifier to standby. Notice that the applied voltage appears at the headstage
input even when the amplifier is in standby mode or when the headstage has open inputs
(i.e. the oscilloscope trace doesn’t change when amp is in standby).
•
Make similar adjustments to the hold control to assure yourself that the amplifier performs as
expected.
•
Switch the
COMMANDS APPLIED
toggle in the
HOLD
block to off.
•
Using the
VOLTAGE
UP
/
DOWN
TOGGLE
switches in the
HOLD
block, adjust hold potential until
the meter reads 0 mV.
•
Place the amplifier into standby.
Input noise test without model membrane
•
Remove the model membrane. Insure that the Faraday cage remains grounded, either
through the headstage grounding jack or to the amplifier grounding posts.
•
Move the BNC connection from the V
m
X
10
OUTPUT
to the I
m
OUTPUT
(in the
OUTPUTS
block)
and monitor the I
m
OUTPUT
with the oscilloscope.
•
Set the amplifier
GAIN
to 100 mV/pA and the oscilloscope voltage base to 50 mV/div.
•
Verify that the
FILTER TOGGLE
is active and switch the
FILTER
control to 1 kHz.
•
Verify that the
COMMANDS APPLIED
toggle in the
HOLD
block is set to off.
•
Switch the
STANDBY
/
OPERATE
switch to operate. You should observe that the noise level
decreases to no greater than 30 mV p-p. At a gain setting of 100 mV/pA this corresponds to a
maximum noise level of 0.043 pA RMS.
•
Place the amplifier into standby.
Input noise test with model membrane
•
Connect the model membrane (
MC-1
) to the headstage inputs and the green wire from the
model membrane to the headstage grounding jack. Insure that the Faraday cage remains
grounded, either through the headstage grounding jack or to the amplifier grounding posts.
•
Set the I
m
GAIN
on the amplifier to 5 mV/pA.
•
Set the oscilloscope voltage base to 10 mV/div.
•
Verify that the filter is set to 1 kHz.
•
Verify that the
COMMANDS APPLIED
toggle in the
HOLD
block is set to off.
Warner
Instruments
A Harvard Apparatus Company .