User
Guide
for
Axoclamp
900A
calculated
offset
is
being
applied.
Offset
value
is
displayed
in
the
adjustable
field.
You
can
fine
‐
tune
the
offset
value
manually
after
pressing
Zero
.
Manual
Check
the
checkbox
and
then
adjust
the
value
to
optimize
the
Scaled
Output
signal
(but
note
that
Zero
is
generally
used
for
this
command).
Additional
Notes
Output
Offset
can
fail
if
the
DC
voltage
is
greater
than
±3
V.
Pipette
Capacitance
Neutralization
Input
Capacitance
The
capacitance
(C
in
)
at
the
input
of
the
headstage
amplifier
is
due
to
the
capacitance
of
the
amplifier
input
itself
(C
in1
)
plus
the
capacitance
to
ground
of
the
microelectrode
and
any
connecting
lead
(C
in2
).
C
in
combined
with
the
microelectrode
resistance
(R
e
)
acts
as
a
lowpass
filter
for
signals
recorded
at
the
tip
of
the
microelectrode.
For
optimal
performance
at
high
frequencies
this
RC
time
constant
must
be
made
as
small
as
possible.
Two
techniques
may
be
used
to
increase
the
recording
bandwidth.
Use
microelectrodes
with
the
lowest
possible
resistance
compatible
with
stable
recording,
and
take
steps
to
minimize
the
contribution
to
C
in
by
the
capacitance
of
the
microelectrode.
In
practice,
this
means
using
patch
electrodes
where
possible,
or
using
sharp
microelectrodes
with
minimal
capacitance
(see
Chapter
4,
Sharp
Microelectrode
Recording
).
Electronically
neutralize
C
in
.
The
second
approach
has
been
implemented
in
the
Axoclamp
900A
in
two
ways.
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