This set of Microprocessors Questions and Answers for Experienced people focuses on “Interfacing Digital to Analog Converters, Stepper Motor Interfacing and Control of High Power Devices Using 8255”.
1. DAC (Digital to Analog Converter) finds application in
a) digitally controlled gains
b) motor speed controls
c) programmable gain amplifiers
d) all of the mentioned
View Answer
Explanation: DAC is used in digitally controlled gains, motor speed controls and programmable gain amplifiers.
2. To save the DAC from negative transients the device connected between OUT1 and OUT2 of AD 7523 is
a) p-n junction diode
b) Zener
c) FET
d) BJT (Bipolar Junction transistor)
View Answer
Explanation: Zener is connected between OUT1 and OUT2 pins of AD7523 to save from negative transients.
3. An operational amplifier connected to the output of AD 7523 is used
a) to convert current output to output voltage
b) to provide additional driving capability
c) as current-to-voltage converter
d) all of the mentioned
View Answer
Explanation: An operational amplifier is used as a current-to-voltage converter to convert current output to output voltage and also provides additional driving capability to the DAC.
4. The DAC 0800 has a settling time of
a) 100 milliseconds
b) 100 microseconds
c) 50 milliseconds
d) 50 microseconds
View Answer
Explanation: DAC 0800 has a settling time of 100 milliseconds.
5. The device that is used to obtain an accurate position control of rotating shafts in terms of steps is
a) DC motor
b) AC motor
c) Stepper motor
d) Servo motor
View Answer
Explanation: Stepper motor employs rotation of its shaft in terms of steps, rather than continuous rotation as in case of AC or DC motors.
6. The internal schematic of a typical stepper motor has
a) 1 winding
b) 2 windings
c) 3 windings
d) 4 windings
View Answer
Explanation: The internal schematic of a typical stepper motor has 4 windings.
7. The number of pulses required for one complete rotation of the shaft of the stepper motor is equal to the
a) number of internal teeth on a rotor
b) number of internal teeth on a stator
c) number of internal teeth on a rotor and stator
d) number of external teeth on a stator
View Answer
Explanation: The number of pulses required for one complete rotation of the shaft of the stepper motor is equal to the number of internal teeth on its rotor.
8. A simple scheme for rotating the shaft of a stepper motor is called
a) rotating scheme
b) shaft scheme
c) wave scheme
d) none
View Answer
Explanation: In this scheme, the windings are applied with the required voltage pulses, in a cyclic fashion.
9. The firing angles of thyristors are controlled by
a) pulse generating circuits
b) relaxation oscillators
c) microprocessor
d) all of the mentioned
View Answer
Explanation: In early days, the firing angles were controlled by pulse generating circuits like relaxation oscillators and now, they are accurately fired using a microprocessor.
10. The Isolation transformers are generally used for
a) protecting low power circuit
b) isolation
c) protecting low power circuit and isolation
d) none
View Answer
Explanation: Any switching component of a high power circuit may be sufficient to damage the microprocessor system. So, to protect the low power circuit isolation transformers are used. They are also used if isolation is necessary.
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