One of the most common and least expensive crystals available is the 3.58 MHz crystal used in color television sets. What hex value would have to be loaded into the counter in Figure 8-12 in order to use the 3.58 MHz crystal to derive the 60Hz reference signal for the clock?
A) 63C0 B) E3C0 C) E912 D) 16ED
Question 2
Which of the statements below best describes the basic operation of a dual-slope A/D converter?
A) A ramp voltage and analog input voltage are applied to a comparator. As the input voltage causes the integrating capacitor to charge, it will at some point equal the ramp voltage. The ramp voltage is measured and displayed on the digital panel meter.
B) A ramp generator is used to enable a counter through a comparator. When the ramp voltage equals the input voltage the counter is latched and then reset. The counter reading is proportional to the input voltage since the ramp is changing at a constant V/second rate.
C) Two ramps are generated: one by the input voltage and the other by a reference voltage. The input voltage ramp charges the integrating capacitor, while the reference voltage discharges the capacitor and enables the counter until the capacitor is discharged, at which time the counter value is loaded into the output latches.
D) The input voltage is used to set the frequency of a voltage-controlled oscillator (VCO). The VCO quits changing frequency when the input voltage stabilizes. The frequency of the VCO, which is proportional to the analog input voltage, is measured and is displayed on the digital display as a voltage reading.
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