PC-505B Manual, Rev. 201013
Warner
Instruments
A Harvard Apparatus Company
36
knob. Commands from all of the sources are summed by the amplifier and applied.
Command currents can be monitored on the meter or at the I
M
OUTPUT
BNC.
External command currents
Maximum current capability produced by an externally applied command signal depend
on the
COMMAND SENSITIVITY
selected. A
10 V
signal applied to the
COMMAND IN
BNC will
produce pipette currents as shown in the table below. (These values assume the headstage
is set with the
PROBE RESISTOR
toggle set to
low.)
COMMAND SENSITIVITY
setting
Attenuated command
voltage with 10 V input
Maximum current
capability
x0.1
1 V
1 nA
x0.01
100 mV
100 pA
X 0.001
10 mV
10 pA
A positive command voltage produces a positive (cation-outward) current from the pipette.
Bilayer recording
Bilayer recording is performed using the
HB-205B
headstage. The
HB-205B
is a switchable
(50 G
/500 M
) headstage modified to allow for compensating the relatively large capacitance
of the bilayer membrane. Up to approximately 250 pF can be compensated. As such, the noise
level for this headstage is about 10% greater than for the standard 50 G
headstage due to the
increased capacitance compensation.
Bilayers are usually formed across an aperture in a cup contained within a Faraday cage.
Because of the high impedance of the bilayer, the assembly
must
be shielded from interference
to obtain low-noise recordings. Warner has a complete Bilayer Workstation available, and if
needed, the amplifier used with that system can be replaced with the
PC-505B
.
Regardless if you’re using the
PC-505B
with Warner’s Bilayer Workstation or with a custom
rig, Plug the
HB-205B
headstage into the
PROBE RECEPTACLE
on the rear of the instrument and
turn the
PROBE SELECT
knob to
high
. The amplifier automatically recognizes the headstage and
illuminates the front panel
BILAYER
light. You can proceed with voltage or current clamp
measurements as desired.
