PC-505B Manual, Rev. 201013
Warner Instruments
A Harvard Apparatus Company
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.)
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.
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