Specifications

CORRECT
FLAT
OVER
COM-
PENSATED
(OVERSHOOT}
UNDER
COtvl-
PENSATED
(ROLLOFF}
465
Figure 11.
Probe eompensation.
INPUT
COUPLING
CAPACITOR
PRECHARGING
ln the
GND
position,
the
input signal
is connected
to
ground
through
a
one-megohm
resistor to
form
a
pre'
charging
network.
This
network allows
the
input
coupling
capacitor
to
charge
to
the average
dc'voltage
level
of the
signal
applied
to
the
probe.
Thus,
any
large
voltage
tran-
sients
accidentally
generated
will
not be
applied
to
the am'
plifier
input.
The
precharging
network
also
provides
a
mea-
sure
of
protection
to
the
external
circuitry
by
reducing
the
current
levels
that
can
be
drawn
from the
external
circuitry
duri
ng capacitor
charging.
The
following
procedure
should
be
used whenever
the
probe
tip
is connected
to
a signal source
having a
different
dc
level than
that
previously
applied,
especially
if the
dc
level
difference
is more than
10
times
the
VOLTS/DIV
setti
ng:
1. Set
the AC-GND-DC
switch
to
GND
before
connect-
ing the
probe
tip to
a signal
source.
2.
Touch
the
probe
tip to
the
oscilloscope
chassis
ground.
3.
Wait
several
seconds
for
the
input
coupling
capacitor
to
discharge.
4. Connect
the
probe
tip
to the signal
source.
Wait several
seconds
for
the
input coupling
capacitor
to
charge.
Set
the
AC-GND-DC
switch
to
AC. The
display
will
remain on
the screen,
and the
ac
component
of
the
signal
can
be
measured
in the
normal
manner.
5.
6.
@
36
4658/DM44
OPerators