Sub Element G7: Practical Circuits

Question 1

What useful feature does a power supply bleeder resistor provide?

Answer 1

It ensures that the filter capacitors are discharged when power is removed

Question 2

Which of the following components are used in a power supply filter network?

Answer 2

Capacitors and inductors

Question 3

Which type of rectifier circuit uses two diodes and a center-tapped transformer?

Answer 3

Full-wave

Question 4

What is an advantage of a half-wave rectifier in a power supply?

Answer 4

Only one diode is required

Question 5

What portion of the AC cycle is converted to DC by a half-wave rectifier?

Answer 5

180 degrees

Question 6

What portion of the AC cycle is converted to DC by a full-wave rectifier?

Answer 6

360 degrees

Question 7

What is the output waveform of an unfiltered full-wave rectifier connected to a resistive load?

Answer 7

A series of DC pulses at twice the frequency of the AC input

Question 8

Which of the following is an advantage of a switch mode power supply as compared to a linear power supply?

Answer 8

High-frequency operation allows the use of smaller components

Question 9

What is the reason for neutralizing the final amplifier stage of a transmitter?

Answer 9

To eliminate self-oscillations

Question 10

Which of these classes of amplifiers has the highest efficiency?

Answer 10

Class C

Question 11

Which of the following describes the function of a two-input AND gate?

Answer 11

Output is high only when both inputs are high

Question 12

Which of the following describes the function of a two input NOR gate?

Answer 12

Output is low when either or both inputs are high

Question 13

How many states does a 3-bit binary counter have?

Answer 13

8

Question 14

What is a shift register?

Answer 14

A clocked array of circuits that passes data in steps along the array

Question 15

Which of the following are basic components of a sine wave oscillator?

Answer 15

A filter and an amplifier operating in a feedback loop

Question 16

How is the efficiency of an RF power amplifier determined?

Answer 16

Divide the RF output power by the DC input power

Question 17

What determines the frequency of an LC oscillator?

Answer 17

The inductance and capacitance in the tank circuit

Question 18

Which of the following describes a linear amplifier?

Answer 18

An amplifier in which the output preserves the input waveform

Question 19

For which of the following modes is a Class C power stage appropriate for amplifying a modulated signal?

Answer 19

FM

Question 20

Which of the following is used to process signals from the balanced modulator then send them to the mixer in some single sideband phone transmitters?

Answer 20

Filter

Question 21

Which circuit is used to combine signals from the carrier oscillator and speech amplifier then send the result to the filter in some single sideband phone transmitters?

Answer 21

Balanced modulator

Question 22

What circuit is used to process signals from the RF amplifier and local oscillator then send the result to the IF filter in a superheterodyne receiver?

Answer 22

Mixer

Question 23

What circuit is used to combine signals from the IF amplifier and BFO and send the result to the AF amplifier in some single sideband receivers?

Answer 23

Product detector

Question 24

Which of the following is an advantage of a direct digital synthesizer (DDS)?

Answer 24

Variable frequency with the stability of a crystal oscillator

Question 25

What should be the impedance of a low-pass filter as compared to the impedance of the transmission line into which it is inserted?

Answer 25

About the same

Question 26

What is the simplest combination of stages that implement a superheterodyne receiver?

Answer 26

HF oscillator, mixer, detector

Question 27

What circuit is used in analog FM receivers to convert IF output signals to audio?

Answer 27

Discriminator

Question 28

What is the phase difference between the I and Q signals that software-defined radio (SDR) equipment uses for modulation and demodulation?

Answer 28

90 degrees

Question 29

What is an advantage of using I and Q signals in software-defined radios (SDRs)?

Answer 29

All types of modulation can be created with appropriate processing.

Question 30

What is meant by the term “software-defined radio” (SDR)?

Answer 30

A radio in which most major signal processing functions are performed by software

Question 31

What is the frequency above which a low-pass filter’s output power is less than half the input power?

Answer 31

Cutoff frequency

Question 32

What term specifies a filter’s maximum ability to reject signals outside its passband?

Answer 32

Ultimate rejection

Question 33

The bandwidth of a band-pass filter is measured between what two frequencies?

Answer 33

Upper and lower half-power

Question 34

What term specifies a filter’s attenuation inside its passband?

Answer 34

Insertion loss

Question 35

Which of the following is a typical application for a Direct Digital Synthesizer?

Answer 35

A high-stability variable frequency oscillator in a transceiver