OPERATING INSTRUCTIONS
G E N E R A L METHODS O F OPERATION
A waveform to be viewed is fed to V . I N P U T terminals (1)
and G N D (2) or (2) and D C terminal ( 3 ) . Adjust the
controls V E R T . A T T (4) and V . G A I N (11) so that the
displayed waveform is 4 0 to 60 mm high on the vertical
axis. F o r adjustments, refer to the items 4 and 11 of the
operating procedure outlined on the panel. T h e n obtain an
appropriate number of waveform peaks by adjusting the
controls S W E E P R A N G E (6) and V A R / H . G A I N ( 1 0 ) . T h e
displayed waveform must be synchronized to a steady
state. If the waveform contains only a single complete
cycle on C R T , it means that the time base frequency is
identical with the frequency of the signal being displayed.
In contrast with this, if the waveform contains five peaks,
the time base frequency is 1/5 of the frequency being
displayed. Waveforms displayed with frequencies as low as
below 50 Hz may cause flickering on C R T due to the slow
movement of spot.
T h i s phenomenon is eliminated as the time base frequency
gets higher than 50 Hz. B y using the V . I N P U T D C
terminal, the D C component of displayed waveform can be
measured or frequencies below 10 Hz can be viewed. When
observing A C component only, the V . I N P U T A C terminal
is used.
T h e polarity of displayed waveform is positive in the upper
direction of C R T and in the right-direction when viewed in
the horizontal direction.
T h e position of the waveform on C R T can be centered by
adjusting the controls (9) and ( 1 2 ) . Since the waveform
shifts up or down depending on the polarity of the D C
component, i t ' m u s t be corrected by adjusting the control
( 1 2 ) . If the waveform cannot be set in the center of the
screen even after the adjustment of the control ( 1 2 ) , it is an
indication that the D C component is too high and,
therefore, the controls (4) and (11) must be adjusted
appropriately until the waveform is centered.
T o measure the voltage of the displayed waveform, cali-
brate the amplitude of the waveform appropriately using
the scale on the screen as a guide and read the sensitivity
obtained.
Amplitude
Ampl itude
( P o s i t i v e s q u a r e w a v e )
W i t h A C - D C s e l e c t o r s w i t c h
s e t a t p o s i t i o n
DC.
Calculate the
voltage according to
the
equation below.
Voltage = Amplitude
x
sensitivity
A s an alternative, the voltage can be obtained by a
proportional calculation method using a waveform of a
known voltage; for example, if the amplitude of the signal
having 3 V p p of voltage is 4 cm (the sensitivity of the
oscilloscope is 3 V p p
-f
4
cm
= 0 . 7 5 V / c m ) and the ampli-
tude of unknown waveform is 6 c m , then:
3 V p p X V p p 3 V p p x 6cm
— _
=
— _ so „ — = X V p p
4
cm
6
cm
4
cm
Therefore, X = 4 . 5 V p p
All
levels on the oscilloscope are in peak-to-peak values
and,
therefore, must be converted into corresponding effective
values since effective values are commonly used in practice.
In this conversion, however, it should be noted that the
relationship between the effective value and the amplitude
varies according to the type of waveform. Some typical
relationships between two are given for reference:
Waveforms
Effective values
(rms)
Y
= 0 . 5 A
2 / 3 "
0 . 2 8 8 A
Fig. 2 Measurement of A C and DC components
6
" 7 ?
=
0
7
0
7
A
275=0.
354A
A
y =
0 . 5 A
l In
W i t h A C - D C s e l e c t o r s w i t c h
set a t p o s i t i o n A C .