Commander
Reference
Additional
Notes
Tuning
generates
a
Sync
Output.
Tuning
is
the
current
clamp
equivalent
of
Seal
Test
in
voltage
clamp.
V
‐
Clamp
Control
Gain
See
Detect
Oscillation
.
Lag
A
voltage
clamp
is
a
negative
‐
feedback
circuit
and
as
such
it
requires
a
90°
phase
shift
within
the
circuit.
Ideally
this
phase
shift
is
supplied
by
the
capacitance
of
the
membrane.
In
practice,
membranes
introduce
significantly
less
than
90°
phase
shift
(see
discussion
by
Finkel
&
Gage,
1985).
The
frequency
response
of
the
voltage
‐
clamp
circuit
can
be
modified
by
the
Lag
control.
The
voltage
‐
clamp
circuit
can
thereby
be
adjusted
to
compensate
for
the
non
‐
ideal
phase
response
of
real
membranes.
The
controls
are
in
the
Axoclamp
900A
Commander,
in
the
Voltage
Clamp
Control
section
of
the
TEVC
and
dSEVC
tabs.
Phase
lag
cuts
the
high
‐
frequency
gain
of
the
voltage
‐
clamp
circuit.
This
can
be
used
to
reduce
the
noise
but
at
the
same
time
it
slows
the
response
and
introduces
ringing.
In
the
extreme
lag
position
the
phase
‐
control
circuit
introduces
pure
lag.
In
some
instances
no
phase
lag
is
required
(
e
.g.,
with
an
RC
cell
model
the
best
TEVC
or
dSEVC
is
achieved
when
no
phase
lag
is
used).
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