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SECTION 3
CIRCUIT DESCRIPTION
BLOCK DIAGRAM
The
Block
Diagram
shows
interconnections
of the functional
parts
of the oscilloscope, except the power
supplies.
Functions
of
the
switches
are
shown
instead
of
their actual connections.
Plug-In Preamplifiers
In
the
upper
left
of
the Block
Diagram
is
shown the vertical-deflection system. The block
labeled " Plug-Ins"
represents one
of the plug-in
preamplifiers available.
Connections for power
in and
signal-out are made through a multiple-
contact
mating
plug
and socket.
Output
from
these
units
is
push-pull
at
low
impedance.
Main-Unit Amplifier
The
main-unit
amplifier amplifies the signal
and
drives
the delay
line which
terminates
in
the vertical deflection plates.
The trigger pick-
off circuits obtain a sample ofthe vertical signal
for triggering the sweep,
Delay
Line
In
the
Type
531,
the
balanced
24-section
lumped-section delay line adds 1/4 microsecond
of delay to the signal so that the sweep circuits
will have
time
to get the cathode-ray spot un-
blanked
and sweeping before the signal reaches
the vertical-deflection plates.
In the Type
541, a balanced 50-section delay
line adds
.2 microseconds
of delay
for sweep
unblanking purposes.
Trigger Cathode Followers
The trigger signal from the main-unit ampli-
fier passes through two cathode followers.
The
first applies
the signal at low impedance to the
trigger amplifier and the second connects to the
front-panel
VERT.
SIG,
OUT
binding
post.
Trigger Amplifier
The trigger amplifier provides either in-phase
Ger
531/541—CI RCUIT
DESCRIPTION
or inverted output in order to provide negative-
going
output
for either negative-going or posi-
tive-going input trigger signals.
Trigger Shaper
The
trigger-shaper
amplifier makes
a sharp
pulse
from
the trigger
signal
at a time during
the sloping part of the trigger signal determined
by the setting of the triggering-level control.
A
sharpened
negative-going
pulse
triggers
the
multivibrator.
Multivibrator
The multivibrator turns on the sweep genera-
tor and generates the crt-tube unblanking pulse
when it is switched from its quiescent state. The
sharp
negative-going
trigger
signal
from
the
trigger-shaper
circuit trips
the multivibrator,
which
thereafter
stays in the second state until
the
sweep
generator
reverts
it to its quiescent
state.
Sweep Generator
The
sweep
generator
is a Miller
integrator
that
produces
a positive-going
sawtooth
about
150
volts
peak-to-peak.
The
sweep
generator
turns
itself
off when
it reaches
a prescribed
level determined by the sweep-length control, by
transmitting
a signal through the trigger-hold-
off circuits to the multivibrator.
Trigger Holdoff
PAGE 3-1
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