6-20
Figure 6-23.—Vertical-deflection controls.
COMPONENTS USED TO DETERMINE PERIOD TIME OF THE DISPLAY
The TIME/DIV (figure 6-24) controls on the scope determine the period time of the displayed
waveform. As we discussed earlier, the sweep generator develops the sawtooth waveform that is applied
to the horizontal-deflection plates of the CRT. This sawtooth voltage causes the beam to move across the
screen. This trace (sometimes called SWEEP) sets the frequency of the TIME BASE of the oscilloscope.
The frequency of the time base is variable, which enables the oscilloscope to accept a wide range of input
frequencies. Again, two controls are used (figure 6-24). One is a multiposition switch (TIME/DIV) that
changes the frequency of the sweep generator in steps. The second control is a potentiometer (VAR) that
varies the frequency between steps. Each step on the TIME/DIV control is calibrated. The front panel has
markings that group the numbers into microseconds and milliseconds.
