PC-505B Manual, Rev. 201013
Warner
Instruments
A Harvard Apparatus Company
12
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 M
resistor
•
± 200 nA with the 50 M
resistor
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 g
ain scale modifier. The clipping LED lights when the
instrument I
m
output exceeds the amplifier limits.
4-Pole Bessel filter
The I
m
output 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 I
m
signal is present at
two BNC outputs labeled I
m
located 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.
