Operating Instructions-Type
453/R453
applied
to the
EXT
HORIZ input connector
(8
EXT
TRIG
INPUT).
The
signal coupling provided
by
the B COUPLING
switch can be
used
to select
or
reject components
of
the
external horizontal signal (all components
of
external hori-
zontal signal accepted in DC position). Using this mode
of
operation, the horizontal deflection factor
is
uncalibrated.
External horizontql deflection factor
is
about
270 millivolts/
division in the
EXT
position
of
the B
SOURCE
switch and
about
2.7 volts/division in the
EXT
-;-
10
position.
A and B Gate
The
A and B
Gate
output connectors
(on
side panel) pro-
vide a rectangular output pulse which
is
coincident with the
sweep time
of
the respective sweep generator.
This
rectangu-
lar
pulse
is
about
+
12
volts in amplitude (into high-imped-
ance loads) with pulse duration the same
as
the respective
sweep.
Intensity Modulation
Intensity (Z-axis) modulation can be
used
to relate a third
item
of
electrical phenomena to the vertical (Y-axis) and the
horizontal {X-axis) coordinates
without
changing the wave
shape.
The
Z-axis modulating signal
applied
to the
CRT
circuit changes the intensity
of
the displayed waveform to
provide this display.
"Gray
scale" intensity modulation can
be obtained
by
applying
signals which
do
not completely
blank the display. Large amplitude signals
of
the correct
polarity
will completely blank the display; the sharpest dis-
play
is
provided
by
signals with a fast
rise
and fall.
The
voltage amplitude required for visible trace modulation
depends upon the setting
of
the INTENSITY control.
At
normal intensity level, a five-volt peak-to-peak signal pro-
duces a visible change in brightness.
When
the Z AXIS
INPUT
is
not in
use,
keep the ground strap in place to pre-
vent changes in trace intensity due to extraneous noise.
Time markers
applied
to the Z AXIS INPUT connector
provide a direct time reference on the display.
With
uncali-
brated horizontal sweep
or
external horizontal mode opera-
tion, the time markers provide a means
of
reading time
directly from the display. However,
if
the markers are
not
time-related to the displayed waveform, a single-sweep
display should be
used
(for internal sweep only) to provide
a stable display.
Calibrator
The one-kilohertz square-wave
Calibrator
of
the Type 453
provides a convenient signal source
for
checking basic verti-
cal gain and sweep timing. However, to provide maximum
measurement acuracy, the adjustment procedure given in the
Calibration section
of
this manual should be used.
The
Calibrator
output signal
is
also very useful for adjusting
probe compensation
as
described in the probe instruction
manual.
In
addition, the
calibrator
can be
used
as
a con-
venient signal source
for
application to external equipment.
Voltage.
The
Calibrator
provides accurate peak-to-peak
square-wave voltages
of
0.1
and 1
volt
into a high imped-
ance load. Voltage range
is
selected by the CALIBRATOR
switch
on
the side panel.
Output
resistance
is
about
200
ohms in the 1 V position and
about
20
ohms in the
0.1
V
2-20
position. The actual voltage across an external
load
resistor
can be calculated in the same manner
as
with
any
series
resistor combination (necessary only
if
the·
load
resistance
is
less
than
about
50
kilohms).
Current.
The
current loop, located on the side panel,
provides a five milliampere peak-to-peak square-wave cur-
rent which can be
used
to check and calibrate current-
measuring probe
systems.
This
current signal
is
obtained
by
clipping the probe around the current loop. Current
is
constant through the
loop
in either position
of
the CALI-
BRATOR
switch.
The
arrow
above the
PROBE
LOOP indi-
cates conventional current flow; i.e., from
+ to
-.
Frequency.
The
Calibrator
circuit
uses
frequency-stable
components to maintain accurate frequency and constant
duty
cycle.
Thus
the
Calibrator
can be
used
for checking
the basic sweep timing
of
the horizontal system.
Wave
shape.
The
square-wave output signal
of
the Cali-
brator
can be
used
as
a reference wave shape when check-
ing
or
adjusting the compensation
of
passive, high-resistance
probes. Since the square-wave output from the
Calibrator
has
a
flat
top, any distortion in the displayed waveform
is
due to the probe compensation.
BASIC
APPLICATIONS
General
The
following information describes the procedure and
technique for making basic measurements with a Type 453
,;11111
Oscilloscope.
These
applications are not described
in
detail
since each application must be
adapted
to the requirements
of
the individual measurements. Familiarity with the Type
453 will permit these basic techniques to be
applied
to a
wide variety
of
uses.
Peak-to-Peak Voltage
Measurements-AC
To
make a peak-to-peak voltage measurement,
use
the
following procedure:
1.
Connect the signal to either INPUT connector.
2.
Set
the
MODE
switch to display the channel used.
3.
Set
the VOLTS/DIV switch to display
about
five divi-
sions
of
the waveform.
4.
Set
the Input Coupling switch to AC.
NOTE
For
low-frequency
signals
below
about
16
hertz,
use
the
DC
position.
5.
Set the A Triggering controls to
obtain
a stable dis-
play.
Set
the TIME/DIV switch to a position that displays
several cycles
of
the waveform.
6.
Turn the vertical POSITION control
so
the lower por-
tion
of
the waveform coincides with one
of
the graticule
lines below the center horizontal line, and the top
of
the
,,....
waveform
is
on the viewing area.
Move
the display with
the horizontal POSITION control
so
one
of
the upper peaks
lies near the center vertical line
(see
Fig. 2-15).
®
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