Engineering Questions with Answers - Multiple Choice Questions

MCQs on Interfacing Digital to Analog Converters, Stepper Motor Interfacing and Control of High Power Devices Using 8255

1 - Question

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

Answer: d
Explanation: DAC is used in digitally controlled gains, motor speed controls and programmable gain amplifiers.




2 - Question

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

Answer: b
Explanation: Zener is connected between OUT1 and OUT2 pins of AD7523 to save from negative transients.




3 - Question

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

Answer: d
Explanation: An operational amplifier is used as a current-to-voltage converter to convert the current output to output voltage and also provides additional driving capability to the DAC.




4 - Question

The DAC 0800 has a settling time of
a) 100 milliseconds
b) 100 microseconds
c) 50 milliseconds
d) 50 microseconds

View Answer

Answer: a
Explanation: DAC 0800 has a settling time of 100 milliseconds.




5 - Question

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

Answer: c
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 - Question

The internal schematic of a typical stepper motor has
a) 1 winding
b) 2 windings
c) 3 windings
d) 4 windings

View Answer

Answer: d
Explanation: The internal schematic of a typical stepper motor has 4 windings.




7 - Question

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

Answer: a
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 - Question

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

Answer: c
Explanation: In this scheme, the windings are applied with the required voltage pulses, in a cyclic fashion.




9 - Question

The firing angles of thyristors are controlled by
a) pulse generating circuits
b) relaxation oscillators
c) microprocessor
d) all of the mentioned

View Answer

Answer: d
Explanation: In early days, the firing angles were controlled by a pulse generating circuits like relaxation oscillators and now, they are accurately fired using a microprocessor.




10 - Question

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

Answer: c
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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