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Vertical POSITION Control
COMPONENTS USED TO SELECT THE VERTICAL OPERATING MODE

Neets Module 16-Introduction to Test Equipment
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6-18 Figure 6-20.—Vertical input arrangement. The VERTICAL-DEFLECTION AMPLIFIER increases the amplitude of the input signal level required for the deflection of the CRT beam. The deflection amplifier must not have any other effect on the signal, such as changing the shape (called DISTORTION). Figure 6-21 shows the results of distortion occurring in a deflection amplifier. Figure 6-21.—Deflection amplifier distortion. Attenuator Control An amplifier can handle only a limited range of input amplitudes before it begins to distort the signal. Signal distortion is prevented in oscilloscopes by the incorporation of circuitry that permits adjustment of the input signal amplitude to a level that prevents distortion from occurring. This adjustment is called the ATTENUATOR control in some scopes (VOLTS/DIV and VAR in figure 6-19). This control extends the usefulness of the oscilloscope by enabling it to handle a wide range of signal amplitudes. The attenuator usually consists of two controls. One is a multiposition (VOLTS/DIV) control, and the other is a variable (VAR) potentiometer. Each position of the control may be marked either as to the amount of voltage required to deflect the beam a unit distance, such as VOLTS/DIV, or as to the amount of attenuation (called the DEFLECTION FACTOR) given to the signal, such as 100, 10, or 1. Suppose the .5 VOLTS/DIV position were selected. In this position, the beam would deflect vertically 1 division for every 0.5 volts of applied signal. If a sine wave occupied 4 divisions peak-to- peak, its amplitude would be 2 volts peak-to-peak (4 0.5), as shown in figure 6-22.






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