Online Digital Electronics Test - Digital Electronics Test 7

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Total number of questions: 20.
Time allotted: 30 minutes.
Each question carries 1 mark; there are no negative marks.
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What is an analog-to-digital converter?

It makes digital signals.

It takes analog signals and puts them in digital format.

It allows the use of digital signals in everyday life.

It stores information on a CD.

[#]

The controls on an oscilloscope that will help obtain a stable display are in the ________.

vertical section

horizontal section

trigger section

display section

[#]

Hex is often used in digital applications as a shorthand way to represent strings of bits.

True

False

[#]

Use Boolean algebra to find the most simplified SOP expression for F = ABD + CD + ACD + ABC + ABCD.

F = ABD + ABC + CD

F = CD + AD

F = BC + AB

F = AC + AD

[#]

The Boolean expression C + CD is equal to ________.

C + D

[#]

As a technician you are confronted with a TTL circuit board containing dozens of IC chips. You have taken several readings at numerous IC chips, but the readings are inconclusive because of their erratic nature. Of the possible faults listed, select the one that most probably is causing the problem.

A defective IC chip that is drawing excessive current from the power supply

A solar bridge between the inputs on the first IC chip on the board

An open input on the first IC chip on the board

A defective output IC chip that has an internal open to V_cc

[#]

For the XNOR gate truth table shown below, the values for w, x, y, and z are ____, ____, ____, and ____, respectively.

1, 0, 0, 1

0, 1, 0, 1

1, 1, 1, 0

1, 0, 0, 0

[#]

The output pulse width for a 555 monostable circuit with R₁ = 3.3 k

and C₁ = 0.02

F is ________.

7.3

7.3 ms

73 ms

[#]

The J-K flip-flop is a standard building block of clocked (sequential) logic circuits known as a ________.

FUNCTION

logic primitive

VARIABLE

PROCESS

[#]

10.

A glitch that appears on the decoded output of a ripple counter is often difficult to see on an oscilloscope because ________.

it is a random event

it occurs less frequently than the normal decoded output

it is very fast

all of the above

[#]

11.

Which is not part of a hard disk drive?

Spindle

Platter

Read/write head

Valve

[#]

12.

Each programmable array logic (PAL) gate product is applied to an OR gate and, if combinational logic is desired, the product is ORed and then:

the polarity fuse is restored

sent to an inverter for output

sent immediately to an output pin

passed to the AND function for output

[#]

13.

The programming technologies that are used in CPLD devices are all nonvolatile.

True

False

[#]

14.

The GAL22V10 has 12 outputs pins and 10 input pins.

True

False

[#]

15.

The symbol shown below is an AND gate.

True

False

[#]

16.

Add the following BCD numbers.

0110		0111		1001
0101		1000		1000

0000 1011 0000 1111 0001 0001

0001 0001 0001 0101 0001 0001

0000 1011 0000 1111 0001 0111

0001 0001 0001 0101 0001 0111

[#]

17.

Whenever a totem-pole TTL output goes from LOW to HIGH, a high-amplitude current spike is drawn from the V_cc supply. How is this effect corrected to a digital circuit?

By connecting a radio-frequency capacitor from V_cc to ground.

By using a switching power supply

By connecting a capacitor from V_out to ground

By connecting a large resistor from V_cc to V_out

[#]

18.

What is the purpose of a decoder's inputs?

To allow the decoder to respond to the inputs to activate the correct output gate.

To disable the decoder outputs so that all outputs will be inactive.

To disable the inputs and activate all outputs.

To allow the decoder to respond to the inputs to activate the correct output gate, and to disable the inputs and activate all outputs.

[#]

19.

In a typical IC monostable multivibrator circuit, at the falling edge of the trigger input, the output switches HIGH for a period of time determined by the ________.

value of the RC timing components

amplitude of the input trigger

frequency of the input trigger

magnitude of the dc supply voltage

[#]

20.

A microcontroller is called a computer on a chip.

True

False

[#]

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Online Digital Electronics Test - Digital Electronics Test 7

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