J
l
J
]
l
l
J
J
l
Set
the
input
coupling
switch
to
GND
and
position
the
baseline
to
a
convenient
reference line. For
examplE:l,
if
the
voltage
to
be measured is positive, then
position
the
baseline
to
the
bottom
graticule
line.
Switch
the
Input Coupling
Switch
to
DC. Measure the
divisions
of
vertical
deflection
between the reference line
and
the
desired
point
on the waveform (see Fig. 17).
Multiply
the
veritcal
deflection
by
the VOL
TS/DIV
switch
setting.
Include
the
attenuation
factor
of
the
probe
if the
probe
does
not
have a
scale-factor
switching
connector.
EXAMPLE:
The
vertical
distance
measured is
4.6
divisions
(see Fig. 17), the waveform is above the
reference line, and the
VOL
TS/DIV
switch
is set
to
2.
Using
the
formula:
Instan-
taneous
Voltage
vertical
VOLTS/
distance
X
polarity
X DIV
(divisions)
setting
Substituting:=
4.6 X
(+1)
X 2 V = 9.2 volts.
If a negative voltage is
to
be measured,
position
the
trace
to
the top
graticule
line and measure from C
to
B (see
Fig. 17).
The
ground
reference
line
can be checked at
any
time
by
switching
to
the
GND
position.
£._
:~GATIVE
REFERENCE
LINE
©--/
I
100
..
I
90-+----+-...---+®
B I MEASURE
,__
..,.\,-t--t-t-+-1-+--t--+-t
AMPLITUDE
--+--+--t--+-+-+--r+--f+11r-t--+-t--+--+-++-,-t--
A TO B
T-
-
--
---
l
A~~ti~~v~E
VERTICAL C
TO
B
DE
FjLECTI
:r_+----+-.........,__._-+--"""---+~-+--'--+-~+----l
f-----t-
---
-~
=~"-~·
·-·~~~-~~-~~~
1737·05
Fig. 17. Instantaneous voltage measurement.
This method can also be used
to
measure one voltage
with
respect
to
another. Position one
of
the voltage levels
to
a convenient reference line. Measure the
divisions
of
vertical deflection between the reference line and
the
other
voltage level.
Substitute
this value in the
formula
just
given.
@
466/464 DM44 Operators
37
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