Warner PC-505B User manual
PC-505B Manual, Rev. 201013
Warner Instruments
Whole Cell/Patch Clamp Amplifier
Model PC-505B
Warner Instruments
1125 Dixwell Avenue, Hamden, CT 06514
(800) 232-2380 / (800) 547-6766 - support
www.warneronline.com
PC-505B Manual, Rev. 201013
Table of Contents
INTRODUCTION.......................................................................................................................................4
NOMENCLATURE....................................................................................................................................6
Text conventions.....................................................................................................................................6
Device panel abbreviations....................................................................................................................6
Signal polarity conventions....................................................................................................................6
Membrane current (Im).........................................................................................................................6
Membrane potential (Vm) ....................................................................................................................7
CONTROL DESCRIPTION......................................................................................................................8
Front panel..............................................................................................................................................8
COMMANDS block..................................................................................................................................8
FAST CAP COMP (fast capacitance compensation) command block...................................................10
WHOLE CELL COMMAND BLOCK...........................................................................................................10
OUTPUT command block ....................................................................................................................11
METER section ....................................................................................................................................13
Front and rear panel BNC’s and connectors.....................................................................................13
Headstage...........................................................................................................................................16
Electrode holders ...............................................................................................................................16
Model Cell..........................................................................................................................................17
SETUP AND INITIAL TEST..................................................................................................................18
Line voltage...........................................................................................................................................18
Instrument grounding..........................................................................................................................18
Headstage precautions .........................................................................................................................18
Headstage preparation.........................................................................................................................19
Test Procedures ....................................................................................................................................19
Initial connections..............................................................................................................................19
Initial configuration ...........................................................................................................................19
RMS noise checkout............................................................................................................................21
Imoutput checkout ..............................................................................................................................21
Junction zero checkout.......................................................................................................................21
Internal DC voltage command checkout............................................................................................21
External DC Voltage command checkout...........................................................................................22
Internal AC voltage command checkout.............................................................................................23
Auto Zero control checkout................................................................................................................23
Vc commands checkout....................................................................................................................23
PC-505B Manual, Rev. 201013
Cap Comp checkout............................................................................................................................24
Current clamp checkout .....................................................................................................................24
OPERATION............................................................................................................................................26
Initial settings........................................................................................................................................26
Preliminary ...........................................................................................................................................27
Mount the electrode............................................................................................................................27
Submerge the electrode tip.................................................................................................................27
Zero the pipette offset.........................................................................................................................27
Measure the pipette resistance (RP)...................................................................................................28
Voltage clamp........................................................................................................................................29
Attach to the cell and form gigaseal...................................................................................................29
Set electrode capacitance compensation............................................................................................30
Measure seal resistance (RS) .............................................................................................................30
Patch or whole cell recording?..........................................................................................................31
Patch recording - Leak subtraction....................................................................................................31
Patch recording –Excised patch........................................................................................................31
Patch recording - Cell-attached patch...............................................................................................32
Whole-cell recording –Initial conditions...........................................................................................32
Whole-cell recording - Rupture the membrane patch........................................................................32
Whole-cell recording - Series R compensation..................................................................................33
Whole-cell recording - % correction..................................................................................................34
Current clamp.......................................................................................................................................35
Switching into current clamp .............................................................................................................35
Recording in current clamp................................................................................................................35
External command currents ...............................................................................................................36
Bilayer recording..................................................................................................................................36
THEORETICAL CONSIDERATIONS .................................................................................................37
Chloriding silver wire...........................................................................................................................37
Chloriding by electrolysis ..................................................................................................................37
Chloriding chemically........................................................................................................................37
Electrode holders..................................................................................................................................37
Care and use of holders......................................................................................................................38
Cleaning and storage .........................................................................................................................38
Replacing holder parts.......................................................................................................................38
Reference electrodes.............................................................................................................................39
APPENDIX................................................................................................................................................40
Specifications.........................................................................................................................................40
Accessories and replacement parts.....................................................................................................42
Warranty and service...........................................................................................................................43
Warranty.............................................................................................................................................43
Service notes.......................................................................................................................................43
PC-505B Manual, Rev. 201013
Recommended reading.........................................................................................................................44
Glossary.................................................................................................................................................47
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The PC-505B Whole Cell/Patch Clamp Amplifier is a low noise, resistive-feedback patch clamp
designed for whole-cell, single channel, and bilayer applications. The unique circuitry and
dedicated design of this amplifier allows Warner Instruments to present a superior quality
instrument at a cost significantly below that of many of our competitors.
Principal features of the PC-505B include:
✓Low noise levels of 0.038 pA RMS at 1 kHz
✓Built-in RMS noise monitor
✓Voltage and current clamp modes with independently selectable Vhold and Ihold
✓Bandwidth to 25 kHz
✓Internal 4-pole low-pass Bessel filter with rear panel filter telegraph
✓Built-in test generator
✓Automatic junction potential compensation
✓Two-range fast capacitance compensation
✓Series resistance and C-slow capacitance compensation
✓% Correction circuitry
✓Adjustable duration zap circuit for whole cell membrane penetration
✓Output gain selection with rear-panel gain telegraph
✓Front/rear panel controls and connectors are color coded and organized for quick
reference and convenient operation
THIS EQUIPMENT IS NOT DESIGNED NOR INTENDED
FOR USE ON HUMAN SUBJECTS
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NOMENCLATURE
Text conventions
This manual refers to amplifier controls at three functional levels; control blocks, specific
controls within a block, and settings of specific controls. To minimize the potential for confusion,
we have employed several text conventions which are specified below. Since our goal is to provide
clarity rather than complexity, we welcome any feedback you may wish to provide.
➢Warner Instrument product numbers are presented using bold type.
➢References to instrument panel control blocks are specified using UNDERLINED SMALL CAPS.
➢References to specific controls within a block are specified using SMALL CAPS.
➢References to individual control settings are specified using italic type.
➢Special comments and warnings are presented in highlighted text.
Any other formatting should be apparent from context.
Device panel abbreviations
Many controls on the PC-505B have abbreviations associated with them. Several of these
abbreviations are listed here for quick reference. In addition, these and other terms have been
collected and are included in a Glossary at the back of this manual.
Term
Meaning
Sections
CAP COMP
capacitance compensation
FAST CAP COMP
Im
output current
OUTPUT,METER,REAR PANEL
Vm
membrane voltage
OUTPUT,METER,REAR PANEL
Vc
COMMAND IN voltage
OUTPUT,METER,REAR PANEL
Vc
sum of all command and
compensation voltages
METER
Vc+ h IN
Vcplus HOLDING voltage
METER
P STAT
potentiostat mode
OUTPUT,REAR PANEL
Signal polarity conventions
Membrane current (Im)
Imis indicated as positive when cations flow outward from the pipet tip, through the cell
membrane and into the bath, and/or when anions flow from the bath into the pipet. With
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outside-out patch and whole cell preparations, this corresponds to the conventional
physiological definition of outward transmembrane current. With inside-out or cell-attached
patches, the physiological transmembrane current equals minus the indicated Im.
Membrane potential (Vm)
Membrane potential is defined as pipet potential minus bath potential. With outside-
out patch and whole cell preparations, this corresponds to the conventional physiological
definition of transmembrane potential. With inside-out or cell-attached patches, the
physiological transmembrane potential equals minus the indicated Vm.
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CONTROL DESCRIPTION
The instrument front panel is divided into several control blocks. Controls within these
blocks are dedicated towards a common functional purpose. Each control block is outlined in
blue and is clearly labeled as COMMANDS,FAST CAP COMP,WHOLE CELL,and OUTPUT. A final section
contains the LCD METER,as well as the METER SELECT and POWER switches. This section will be
referred to as the METER block.
Front panel
COMMANDS block
The COMMANDS block
contains the VOLTAGE and
CURRENT HOLDING controls, the
JUNCTION ZERO controls, and a
COMMAND SELECT toggle switch
selecting internal or external
command inputs. This block
also contains several controls for
adjusting the sensitivity of input
commands, as well as controls
for the ZAP function.
Voltage and current commands
The VOLTAGE and CURRENT
HOLD controls provide independent modification of holding potential and holding current
settings within the ranges ± 200 mV and ± 1.0 nA, respectively. A MODE toggle switch in the
OUTPUT command block is used to select between voltage clamp (Vc) or current clamp (Ic)
modes. Placing the instrument in current or voltage clamp mode activates either the VOLTAGE
or CURRENT HOLD controls, respectively. This structure allows switching between voltage and
current clamping configurations without the need to readjust settings. VOLTAGE and CURRENT
HOLD controls are not attenuated by COMMAND SENSITIVITY settings.
Internal command, external command, and command sensitivity
The COMMAND SELECT toggle switch selects between an internally generated (internal
command) or an externally generated (external command) command that is applied to the
COMMAND IN BNC located on the instrument rear panel.
NOTE: When set to external command, the COMMAND SENSITIVITY controls attenuate the signal
applied to the COMMAND IN BNC located on the instrument rear panel. When set to internal
command, the COMMAND SENSITIVITY controls select the scaling of the internally generated
TEST PULSE.
The COMMAND SENSITIVITY controls are comprised of an on/off toggle and a sensitivity
selector. The SENSITIVITY SELECTOR attenuates either the internally generated TEST PULSE or
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any externally applied command voltages connected to the COMMAND IN input BNC by factors
of x0.1, x0.01, and x0.001.
Internal or external commands are activated by moving the COMMAND SENSITIVITY toggle
into the on position. When switched off, these modifiers are disconnected from the COMMAND
pathway.
Test pulse
When internal command is selected and COMMAND SENSITIVITY is switched on, a 1V p-p
square wave test pulse (line frequency; 50/60 Hz) is generated by the PC-505B. The test
pulse is attenuated by the SENSITIVITY SELECTOR toggle and is available for adjustment of
capacitance compensation, measurement of pipet resistance, or for monitoring the formation
of a gigohm seal at the electrode tip.
SENSITIVITY SELECTOR setting
Amplitude of test pulse
square wave (p-p)
x0.1
100 mV
x0.01
10 mV
x0.001
1 mV
When external command is selected, the internal TEST PULSE circuitry is disabled and
commands appearing at the COMMAND IN BNC are attenuated and available to be applied to
the headstage.
Junction Zero and Auto Zero
These controls set the pipette current to zero after the pipette is placed in the test
solution and prior to seal formation. This circuitry is used to compensate for electrode
potentials, liquid junction potentials and other offset voltages, and establishes a zero
baseline reference potential. The 10-turn JUNCTION ZERO control manually adjusts Imbetween
120 mV with immediate response.
With the AUTO ZERO toggle switch in the on position (auto zero LED on) depressing the
associated pushbutton zeros the current automatically. The settling time is rapid when used
with Mpipette resistances, but can take several seconds if used with Gresistances. For
complete compensation, hold the pushbutton in until Imon the METER reads zero.
NOTE: With AUTO ZERO turned on, the manual junction control remains active. In this mode,
depressing the auto zero pushbutton will zero any manual setting, holding potential, and
time-averaged test pulse or command voltage present. Switching AUTO ZERO off restores the
uncompensated current and voltages. To re-zero, repeat using either manual or auto zeroing.
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Zap
The ZAP function generates an internal +1.5 V pulse which is applied to the headstage.
The pulse duration may be adjusted from 0.1 to 10 ms as indicated. A safe/active toggle
switch arms the circuitry and the pulse is initiated when the ZAP button is depressed.
FAST CAP COMP (fast capacitance compensation)
command block
The two pairs of controls, C-FAST 1/FAST 1and C-FAST
2/FAST 2, are used to adjust the amplitude and time
constant (tau) of the circuitry that compensates for
capacitative currents due to the pipet and other stray
capacitances. This is achieved by applying an appropriate
capacitative countercurrent to the headstage input. These
controls are disabled in current clamp mode.
When properly adjusted, FAST CAP COMP controls have
two important functions: 1) to closely align the voltage
clamp waveform at the cell membrane to the command
signal waveform, and 2) to minimize large current
transients associated with rapid changes in applied
membrane potential. These effects, if uncompensated, can
drive the headstage amplifier into saturation, which can result in the loss of several ms of
data while the headstage recovers.
WHOLE CELL COMMAND BLOCK
The WHOLE CELL command block contains
controls for C-SLOW, SERIES R, %CORRECTION, and
LEAK SUBTRACTION. These controls are used to
compensate for the effects of membrane
capacitance and access resistance when the
amplifier is used in whole cell mode. With the
exception of LEAK SUBTRACTION, these controls are
only available when the PROBE RESISTER (in the
OUTPUT command block) is in low mode.
C-Slow
This control is used to compensate for the
whole–cell membrane capacitance. The
compensated capacitance can be read directly
from the lockable 10-turn control. The associated
toggle switch disables C–SLOW allowing comparison with the uncompensated signal.
This control is not available in patch mode since the FAST CAP COMP circuitry is used to
address capacitances in this mode.
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Series R
Series resistance compensation is used to compensate for the voltage drop across the
electrode and access resistance in the experimental setup. This control is used to adjust the
time constant of the C–SLOW control facilitating measurement of membrane resistance which
can be read from the dial.
This control is not available in single channel recording mode since series resistances
are negligible when compared with cell membrane and single channel resistances.
% Correction
% Correction is used to apply voltage compensation to the amplifier to correct for the
voltage drops due to the series resistance. This control is adjusted until the output signal
just begins to oscillate at the leading edge (ringing) of the TEST PULSE during experimental
setup. The control is activated by a toggle switch.
Leak subtraction
Leak subtraction is used to compensate for leakage currents to the bath through the
pipet/membrane seal resistance (RS) or through the membrane patch. For ‘leaky’ seals (RS
~1 G) it is important to correct for the error caused by the shunt resistance of the leak.
This error can usually be ignored with ‘tight’ seals (RS ~10 to 100 G). Fully
counterclockwise rotation of this control switches it off.
NOTE: Do not use LEAK SUBTRACTION if using % CORRECTION in whole cell mode. The
interaction between these two controls can introduce a systematic error into your data!
OUTPUT command block
The OUTPUT command block
contains controls for selecting different
operating modes and headstage
resistors. The instrument gain and filter
controls can also be found here.
Probe resistor select
The headstage resistor is selected
with the PROBE RESISTOR select switch.
The high position selects the 50 G
resistor for both patch and bilayer
headstages (models LC-201, HC-202,and
HB-205, respectively). The low position is
used for whole cell recording and selects the 500 Mresistor in the LC-201 headstage and the
50 Mresistor in the HC-202 headstage. It is not available in the HB-205 headstage.
The low resistor is automatically selected when in current clamp mode,
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Clamp mode switch
In voltage clamp mode (MODE switch in upper position), all command controls are active
with the exception of the CURRENT HOLD command (in COMMANDS block). The range of voltage
clamp potentials at the headstage input is ± 200 mV.
Zero current mode (MODE switch in center position) is a transition mode between voltage
clamp and current clamp. It disengages all commands and functions from the headstage
with the exception of the ZAP controls.
The primary uses for zero current mode are: 1) to protect the preparation when
switching between voltage and current clamp modes, and 2) to preset the voltage hold or
current hold settings prior to switching to voltage or current clamp modes, respectively.
In current clamp mode (MODE switch in lower position), all commands are again active.
The current range at the preparation is limited by the ± 10 V input maximum and the
headstage resistor, as follows:
•± 20 nA with the 500 Mresistor
•± 200 nA with the 50 Mresistor
NOTE: Current clamp mode does not operate with the PROBE SELECT toggle set to high. The
low headstage resistance is automatically selected when in current clamp mode.
Gain
The GAIN control selects the amplifier gain in units of mV/pA. The gain scale on this
control is modified by the PROBE RESISTOR select toggle (x0.1 or x1.0 for the low setting, and
x10 for the high setting).
LED’s indicate the selected gain scale modifier. The clipping LED lights when the
instrument Imoutput exceeds the amplifier limits.
4-Pole Bessel filter
The Imoutput signal can be filtered using the internal low–pass 4-pole Bessel filter
selectable from 50 Hz to 20 kHz in 9 steps. The full amplifier bandwidth of 25 kHz is available
by selecting bypass with the ACTIVE/BYPASS toggle switch. The filtered Imsignal is present at
two BNC outputs labeled Imlocated at both the front and rear panels.
Voltammetry
The PC-505B can be used as a potentiostat for voltammetric measurements. A rear panel
POTENTIOSTAT SWITCH increases maximum output of the VOLTAGE HOLD control (in the
COMMANDS block) to ± 1 V and increases the maximum COMMAND IN signal to ± 2 V. The P STAT
LED lights to indicate on status for this switch.
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METER section
The six METER switch settings interact with other controls as noted. Due to the limiting
bandwidth of the meter display, any high frequency signals presented will be reported as its
DC time average value.
Junction Zero : This selection reports the voltage supplied by the JUNCTION ZERO control used
to compensate offset voltages present in the setup. Full scale reading is 120 mV.
Vc+ h IN:This selection reports the sum of the COMMAND
IN voltage (Vc; after attenuation by command sensitivity)
and the internal holding voltage (h). Full scale reading is
200 mV.
NOTE: To read h alone (in order to set the holding voltage
or holding current) turn COMMAND SENSITIVITY off or set the
external signal to zero.
Vc:This selection reports the sum of all command
voltages. Mathematically, Vc= (Vc+ h IN) + (junction zero)
+ (auto zero) + (Series R). It does not include leak
subtraction. Full scale range is ±200 mV.
Vm: This selection reports the transmembrane potential when in current clamp mode. Full
scale range is 200 mV.
Im: This selection reports the transmembrane current when in voltage clamp mode. Full
scale range is ± 1999 pA.
RMS noise: This selection reports the root mean square (RMS) value of the noise filtered to
a bandwidth of 1 kHz. This reading is valid only when the PROBE RESISTOR select is set to high
since the amplifier gain changes for other settings. The expected reading for the 50 G
resistor (with open input and properly shielded from 60 Hz interference) is approximately
0.040 pA. Full scale range is 1.999 pA RMS.
Front and rear panel BNC’s and connectors
The PC-505B has input and/or output BNC’s on both front and read panels. These
include Imand Vmoutputs, Vcx10 and Vmx10 outputs, GAIN and FILTER TELEGRAPHS, Im/Vm
mode telegraph, SYNC OUTPUT, and COMMAND INPUT.
Front and rear panel layouts are described below. With the exception of the rear panel
COMMAND IN BNC, all connector sleeves are connected to circuit ground and are insulated
from the chassis.
Front panel BNC’s
Vcx10 –Output BNC reporting the sum of all voltages applied to the headstage input.
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Vmx10 –Output BNC reporting the transmembrane potential (active only in current
clamp mode).
Im –Output BNC reporting membrane current in both voltage and current clamp modes.
Rear panel BNC’s
Im/Vm OUT–Output BNC reporting membrane current when instrument is in voltage
clamp mode, and Vmx10 when instrument is in current clamp mode.
Im/VmTELEGRAPH –Provides TTL logic to indicate voltage clamp or current clamp mode.
0=I clamp, 1= V clamp
COMMAND IN –Differential input BNC for voltage command from external sources (e.g.
signal generator or computer). Since the center pin and sleeve are the (+) and (-)
inputs, respectively, the sleeve is not grounded. The applied voltage is attenuated by
the COMMAND SENSITIVITY switch and is available in both voltage and current clamp
modes.
The COMMAND IN input BNC is disengaged when TEST PULSE is active (internal
command), when the COMMAND SENSITIVITY toggle switch is off, or when the amplifier
is in zero current mode (MODE selector switch set to Io).
GAIN TELEGRAPH –Output BNC reporting Imgain as a combination of the GAIN switch
selection and the gain multiplier (x0.1, x1.0 or x10) dependent on the headstage in
use. Telegraphs range from 0.5 to 7.0 V in 0.5 V steps as shown below.
Gain telegraph settings
Imgain (mV/pA)
telegraph out (V)
0.05
0.5
0.1
1.0
0.2
1.5
0.5
2.0
1.0
2.5
2.0
3.0
5.0
3.5
10
4.0
20
4.5
50
5.0
100
5.5
200
6.0
500
6.5
1000
7.0
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FILTER TELEGRAPH –Output BNC reporting the filter setting in use. Telegraphs range from
0.2 to 2.0 V in 0.2 V steps as shown below.
Filter telegraph settings
Frequency (Hz)
telegraph out (V)
50
0.2
100
0.4
200
0.6
500
0.8
1k
1.0
2k
1.2
5k
1.4
10k
1.6
20k
1.8
Bypass
2.0
SYNC OUT –Sync out provides a TTL pulsed output for synchronizing an oscilloscopes or
other equipment with the internally generated 50/60 Hz TEST PULSE or SPEED TEST
signal.
Rear panel connectors and controls
In addition to input and output BNC’s, the instrument rear panel also contains the
headstage cable connector, calibration trimmers, and selector/function switches for PSTAT
and SPEED TEST modes.
Headstage cable connector –The headstage connects to the instrument via an 8–pin DIN
connector.
PSTAT switch –The PC–505B is converted to operate as a potentiostat for voltammetric
measurements by a clockwise rotation of this switch. When switched on, the front
panel PSTAT indicator LED will light. In this mode, the maximum electrode voltage
hold potential is increased to ± 1 V and the COMMAND IN attenuator is modified to
allow command inputs up to ± 2 V.
SPEED TEST is used to re–adjust the rear panel boost trimmers, normally only required
when replacing a headstage. These adjustments are factory set for the headstage
supplied with the instrument.
CMR, BOOST, and GAIN trimpots are factory set. User adjustment may be required if a
headstage is replaced. Adjustments instructions are provided with the new
headstage.
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Grounds –Circuit and chassis ground connectors (black and green, respectively) are
binding posts supplied with a shorting link. For most recording situations, the
shorting link can remain connected with no detrimental effect in amplifier
performance. However, there are occasions where line noise can be reduced if the
two grounds are isolated from each other. We recommend that you test both
connected and unconnected configurations to determine which is best for your setup.
Headstage
The headstage, or probe, is a low leakage current, solid state, current-to-voltage
converter which is switch selectable between two feedback resistors.
The headstage input terminal is a 1 mm jack connector that accepts a 1 mm pin on the
electrode holder. Pin jacks on the side of the headstage provide for grounded and/or driven
shield applications.
The headstage housing is a metal enclosure which serves as a shield which is driven by
the command signal. The attached metal rod is used for mounting to a micromanipulator
and is insulated from the headstage housing. A 2.5 m cable with 8-pin DIN connector
attaches the headstage to the mating connector on the instrument rear panel.
NOTE: Due to the requirement of maintaining the lowest possible instrument noise,
headstage input protection cannot be employed. As such, strict handling precautions are
necessary to avoid damage to the headstage by static discharge. (See page 18 for details.)
Headstage types, applications and features
Headstage Types
Application
Features
LC-201
Patch / Whole Cell
50 G/500Mheadstage.
Single channel currents up to ± 200 pA.
Whole cell currents up to ± 20 nA.
HC-202
Patch / Whole Cell
50 G/50Mheadstage.
Single channel currents up to ± 200 pA.
Whole cell currents up to ± 200 nA.
HB-205
Bilayer studies
50 Gheadstage for bilayer.
Currents up to ± 200 pA.
Bilayer capacitance up to 250 pF.
Electrode holders
Electrode holders connect the glass micropipet electrode to the headstage. A fine
chlorided silver wire, the actual electrode, makes electrical contact between the headstage
input and the electrolyte solution in the micropipet.
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Holders are machined from polycarbonate to minimize electrical noise and are custom
bored to accommodate various diameter pipet electrode glasses. The micropipet is secured
with a rubber gasket and a polycarbonate screw–cap matching the OD of the pipet glass. A
1 mm pin makes electrical contact with the silver wire and plugs the holder onto the
headstage. A 1/16” OD access port is provided for applying suction to seal the pipet tip to
the cell membrane.
NOTE: The standard holder used with the PC–505B is type QSW-AxxP (straight body) where
"xx" specifies the glass OD in mm.
Model Cell
A model cell is included with the instrument. This model cell has three connectors, one
to simulate the bath (10Mto ground), one each to simulate a membrane patch, and one to
simulate a whole cell application. An additional model cell is included with the HB-205
bilayer headstage to simulate a planar lipid bilayer membrane.
The model cell is used in the following familiarization instructions and is a valuable tool
in troubleshooting problems with actual setups.
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SETUP AND INITIAL TEST
Line voltage
Power line voltage requirements for the PC-505B are specified on the serial number
nameplate attached to the chassis rear. They are wired for either 100-130 VAC or 220-240 VAC
at either 50 or 60 Hz. Check to be sure the PC-505B is wired for the line voltage and frequency to
be used.
Instrument grounding
The power cord is fitted with a three-prong grounding type plug and should be plugged into
a properly wired three-wire grounded receptacle. This internally grounds the PC-505B chassis to
the power receptacle ground and insures safe operation of the equipment.
Headstage precautions
The PC-505B headstage is a high-impedance, static-sensitive device as noted on the
protective envelope in which it is shipped. The device can be seriously damaged by static
discharge or inadvertent grounding. Therefore, to insure proper operation and long life, we
recommend you follow these precautions:
1. Always discharge static electricity from your body before handling the headstage.
Your body has a capacitance of around 100-200 pF to ground and can acquire enough static
charge (by handling Styrofoam, touching the face of a video monitor, walking across a dry
carpet, wearing polyester clothing, etc) to alter your electric potential by as much as 10 kV
relative to ground. A discharge of this magnitude through the headstage can render it
useless. We recommend that you electrically discharge yourself either by firmly contacting
a securely-grounded part of the setup with a lightly moistening a finger, or by wearing a
grounded wrist strap available from any electronics store.
2. Do not ground or apply a low-impedance signal the headstage input connector pin.
3. Do not ground the headstage case when the power is on. This includes allowing the
headstage case to inadvertently contact any grounded components, This is necessary since
the case is both isolated from ground and is driven at the command potential.
4. Two 1 mm pin jacks are provided on the side of the headstage for grounded and/or driven
shield applications.
The circuit ground pin jack is insulated from the case and is identified by a black collar. It
is intended to be used for the bath ground and/or shielding around the electrode and holder.
It is not intended as a general equipment ground.
The uninsulated pin jack makes direct contact with the headstage case and is driven at the
command potential. It can be used to drive any additional guard shielding such as a foil
covering or conductive paint applied to the pipette electrode. Insure that the guard shielding
never touches ground.
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Headstage preparation
Using the proper handling precautions described above, connect the headstage cable
connector into the rear panel probe receptacle and connect the Imoutput BNC to an oscilloscope.
The headstage probe normally requires a grounded enclosure (Faraday cage) to shield it from
50/60 Hz line interference.
The shield should be grounded to the (black) circuit ground jack on the rear of the PC-505B
chassis. Place the headstage into the shield enclosure and run the grounding cable to the
amplifier in the same bundle as the headstage cable.
NOTE: As a general rule, cables and wires running to the same location should be bundled to
minimize stray capacitances.
Test Procedures
To perform the following tests of the instrument you will need these tools and components.
•The PC-505B amplifier
•The headstage mounted into a shielded enclosure
•An oscilloscope with BNC cables
•An adjustable DC voltage source
•The model cell shipped with the instrument
Initial connections
Place the amplifier on a counter and make the following connections between the
instrument and oscilloscope.
1. Connect the Imoutput BNC on the instrument front panel to the oscilloscope.
2. Connect the DC voltage source to the COMMAND IN BNC on the instrument rear
panel.
3. Connect the headstage to the amplifier and place the headstage into the shielded
enclosure (Faraday cage). Do not make attachments to the headstage inputs at this
time. Insure that the Faraday cage is grounded as described above.
4. Plug the amplifier, voltage source, and oscilloscope in.
5. Power up the voltage source and oscilloscope.
Initial configuration
Set all controls on the PC-505B to the values specified in the following table. With the
exception of the power switch, this initial configuration will be used to return the amplifier
to a known condition to begin each sub–section during the instrument checkout.
PC-505B Manual, Rev. 201013
Warner Instruments
AHarvard Apparatus Company
20
Begin each checkout section by returning the PC-505B to this known configuration.
Headstage inputs: Open
Front panel controls:
Control
Control block
Initial setting
POWER
METER
off
VOLTAGE HOLD
COMMANDS
fully CCW, toggle switch off
CURRENT HOLD
COMMANDS
fully CCW, toggle switch off
COMMAND SELECT
COMMANDS
external command
COMMAND SENSITIVITY
COMMANDS
off, x0.1
JUNCTION ZERO control
COMMANDS
zero mV
AUTO ZERO toggle
COMMANDS
off
ZAP toggle
COMMANDS
safe
ZAP control
COMMANDS
0.1 ms
C–FAST 1
FAST CAP COMP
fully CCW
C–FAST 2
FAST CAP COMP
fully CCW
FAST 1
FAST CAP COMP
fully CCW
FAST 2
FAST CAP COMP
fully CCW
C–SLOW
WHOLE CELL
fully CCW
C–SLOW toggle
WHOLE CELL
off
SERIES R
WHOLE CELL
fully CCW
LEAK SUBTRACTION
WHOLE CELL
fully CCW, click off
%CORRECTION
WHOLE CELL
fully CCW
%CORRECTION toggle
WHOLE CELL
off
PROBE RESISTOR select
OUTPUT
high
MODE
OUTPUT
Vc
GAIN
OUTPUT
10 mV/pA
FILTER
OUTPUT
10 kHz
FILTER toggle
OUTPUT
active
METER select
METER
Im
Oscilloscope setup:
Control
Setting
Time base
2 ms/div
Voltage base
1 V/div
Trigger
line triggered
Connect Imoutput on instrument front panel to the
oscilloscope
Table of contents
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