2. Instantaneous Voltage
Instantaneous voltage is measured with respect to some
reference potential (usually ground). This reference level is first
established by positioning the trace along a graticule line with the
reference potential applied to the input; then, the instantaneous
voltage is applied and measured above or below the reference line
or voltage. In this type of measurement, the INPUT COUPLING
switch must be in the DC position. This method can also be used to
measure the DC component of a waveform, since the average or
DC value can be measured as a voltage above the reference level.
a. Set the vertical deflection factor to an appropriate setting
for the voltage to be measured, (VOLTS/DIV VAR to CAL)
and set the Trigger LEVEL/SLOPE to AUTO PRESET.
b. Switch the INPUT COUPLING switch to GND if the
reference is to be at ground, or to DC if the reference is to
be a voltage level. Touch the probe tip to the reference
voltage and vertically position the trace to a reference on
any horizontal graticule line. This reference position will
depend on the polarity and amplitude of the input signal.
Do not change the setting of the POSition control after the
reference has been set.
c. Remove the probe tip from the reference and connect it to
the signal source. Adjust the SEC/DIV switch for the
desired display.
d. Measure the vertical amplitude in divisions from the point
to be measured to the reference line.
e. Voltage = measured amplitude (in divisions), multiplied by
the deflection factor.
26
212 Operators Handbook
