# Online Digital Electronics Test - Digital Electronics Test 7

Instruction:

• Total number of questions : 20.
• Time alloted : 30 minutes.
• Each question carry 1 mark, no negative marks.
• DO NOT refresh the page.
• All the best :-).

1.

What is an analog-to-digital converter?

A.
 It makes digital signals.
B.
 It takes analog signals and puts them in digital format.
C.
 It allows the use of digital signals in everyday life.
D.
 It stores information on a CD.

2.

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

A.
 vertical section
B.
 horizontal section
C.
 trigger section
D.
 display section

3.

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

A.
 True
B.
 False

4.

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

A.
 F = ABD + ABC + CD
B.
C.
 F = BC + AB
D.

5.

The Boolean expression C + CD is equal to ________.

A.
 C
B.
 D
C.
 C + D
D.
 1

6.

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.
 A defective IC chip that is drawing excessive current from the power supply
B.
 A solar bridge between the inputs on the first IC chip on the board
C.
 An open input on the first IC chip on the board
D.
 A defective output IC chip that has an internal open to Vcc

7.

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

A.
 1, 0, 0, 1
B.
 0, 1, 0, 1
C.
 1, 1, 1, 0
D.
 1, 0, 0, 0

8.

The output pulse width for a 555 monostable circuit with R1 = 3.3 k and C1 = 0.02 F is ________.

A.
 7.3 s
B.
 73 s
C.
 7.3 ms
D.
 73 ms

9.

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

A.
 FUNCTION
B.
 logic primitive
C.
 VARIABLE
D.
 PROCESS

10.

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

A.
 it is a random event
B.
 it occurs less frequently than the normal decoded output
C.
 it is very fast
D.
 all of the above

11.

Which is not part of a hard disk drive?

A.
 Spindle
B.
 Platter
C.
D.
 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:

A.
 the polarity fuse is restored
B.
 sent to an inverter for output
C.
 sent immediately to an output pin
D.
 passed to the AND function for output

13.

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

A.
 True
B.
 False

14.

The GAL22V10 has 12 outputs pins and 10 input pins.

A.
 True
B.
 False

15.

The symbol shown below is an AND gate.

A.
 True
B.
 False

16.

 0110 0111 1001 0101 1000 1000

A.
 0000  1011    0000  1111    0001  0001
B.
 0001  0001    0001  0101    0001  0001
C.
 0000  1011    0000  1111    0001  0111
D.
 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 Vcc supply. How is this effect corrected to a digital circuit?

A.
 By connecting a radio-frequency capacitor from Vcc to ground.
B.
 By using a switching power supply
C.
 By connecting a capacitor from Vout to ground
D.
 By connecting a large resistor from Vcc to Vout

18.

What is the purpose of a decoder's inputs?

A.
 To allow the decoder to respond to the inputs to activate the correct output gate.
B.
 To disable the decoder outputs so that all outputs will be inactive.
C.
 To disable the inputs and activate all outputs.
D.
 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 ________.

A.
 value of the RC timing components
B.
 amplitude of the input trigger
C.
 frequency of the input trigger
D.
 magnitude of the dc supply voltage

20.

A microcontroller is called a computer on a chip.

A.
 True
B.
 False