Explore topic-wise MCQs in Digital Electronics.

This section includes 105 Mcqs, each offering curated multiple-choice questions to sharpen your Digital Electronics knowledge and support exam preparation. Choose a topic below to get started.

101.

There appears to be a problem with a 7-segment display on a DMM sometimes skipping certain numbers. How would you test the display?

A. Remove the display unit and check each segment diode with an ohmmeter. Replace the defective segments.
B. Apply 5 V directly to each segment of the display and check for individual segment operation. Replace any segment that has voltage applied but is not lit.
C. Tie all of the segments together and connect to Vcc; the number 8 should appear on the display. Now check the display supply voltage to determine if the display is receiving the correct voltage.
D. Connect the DMM to a variable supply and very slowly increase the voltage, while observing for missing digits. Then check the segment voltage to determine whether the display or the display driver is bad.
Answer» E.
Discussion
102.

Refer to the keyboard encoder in figure (a). Sometimes when the 5 key is pressed, the system attached to the keypad does not respond. The 5 input on the 74147 is monitored with a digital storage scope while repeatedly pressing the 5 key, and the waveform in figure (b) is obtained; the P above the trace indicates the points at which the technician pressed the key. What is most likely wrong with the circuit?

A. The switches on the 5 key are intermittent; the contacts need to be cleaned or the switch replaced.
B. The pull-up resistor connected to the 5 key is bad and should be replaced.
C. The common ground connection at the bottom of the 0 key has a bad solder connection; repair the connection.
D. The 74147 is intermittent, possibly due to high temperature, and should be replaced.
Answer» B. The pull-up resistor connected to the 5 key is bad and should be replaced.
Discussion
103.

In an AHDL BCD to binary code converter, how is multiplication by 10 accomplished?

A. By using the shifting of bits
B. By using the library multiplication function
C. By using integer types
D. By using the multiplication operator
Answer» B. By using the library multiplication function
Discussion
104.

A(n) ________ is a combinational logic circuit that compares two input binary quantities and generates outputs to indicate which one has the greater magnitude.

A. demultiplexer
B. code converter
C. magnitude comparator
D. E-MOS
Answer» D. E-MOS
Discussion
105.

Which statement below best describes the function of a decoder?

A. A decoder will convert a decimal number into the proper binary equivalent.
B. A decoder will convert a binary number into a specific output representing a particular character or digit.
C. Decoders are used to prevent improper operation of digital systems.
D. Decoders are special ICs that are used to make it possible for one brand of computer to talk to another.
Answer» C. Decoders are used to prevent improper operation of digital systems.
Discussion