Leader LBO-516 Instruction Manual - page 25
3. Position the AC/GND/DC switch (16) to GND.
4. Use the appropriate vertical POSITION control (17) or
(18) to set the baseline on the central horizontal graticule line.
However, if you know the signal voltage is to be positive,use
the 0% or bottom-most graticule line. If you know the signal
voltage is to be negative, use the 100% or uppermost graticule
line.
NOTE: The vertical POSITION controls must not be
touched again until the measurement is completed.
5. Position the AC/GND/DC switch to DC. The polarity of all
points above the ground-reference line is positive; all points
below the ground-reference line are negative.
CAUTION: Make certain the waveform is not riding
on a high-amplitude DC voltage before positioning the
AC/GND/DC switch.
6. Use the horizontal POSITION control (29) to position any
point of interest on the central vertical graticule line. This line
has additional calibration marks equal to 0.2 major divisions
each. The voltage relative to ground at any point selected is
equal to the number of divisions from that point to the ground-
reference line multiplied by the
VOLTS/DIV setting. In the example used for Figure 2-15,
the voltage for a 0.5 V/div scale is 2.5 V (5.0 div X 0.5 V).
7. If XI0 vertical magnification is used, divide the Step 6
voltage by 10 to get the correct voltage. If 10X attenuator
probes are used, multiply the voltage by 10. However, if X10
vertical magnification and 10X attenuator probes are used,
their effects cancel and the Step 6 voltage can be used
without correction.
2-4-2 Differential Measurement Techniques
Differential measurement techniques allow direct mea-
surement of the voltage drop across "floating" components (both
ends above ground), and measurement of very small signals in
electrically noisy environments (such as exist near high-power AC
machinery).
The control manipulations for differential operation were
explained in paragraph
2-3-6 Additive and Differential
Operation. The technique for making the physical connections
are shown in Figure 2-16. Figure 2-16a shows the simple
technique perfectly satisfactory for measuring high-level signals
on floating signals. In this example, the AC voltage drop (ripple)
across a power choke is observed
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