004 - Power Supplies

Question 1

A-004-001-001
For the same transformer secondary voltage, which rectifier has the highest average output voltage?

(a) Half-wave
(b) Bridge
(c) Quarter-wave
(d) Full-wave centre-tap

Answer 1

A-004-001-001
For the same transformer secondary voltage, which rectifier has the highest average output voltage?

(b) Bridge

Question 2

A-004-001-002
In a half-wave power supply with a capacitor input filter and a load drawing little or no current, the peak inverse voltage (PIV) across the diode can reach _____ times the RMS voltage.

(a) 0.45
(b) 2.8
(c) 5.6
(d) 1.4

Answer 2

A-004-001-002
In a half-wave power supply with a capacitor input filter and a load drawing little or no current, the peak inverse voltage (PIV) across the diode can reach _____ times the RMS voltage.

(b) 2.8

Question 3

A-004-001-003
In a full-wave centre-tap power supply, regardless of load conditions, the peak inverse voltage (PIV) will be _____ times the RMS voltage:

(a) 0.636
(b) 0.707
(c) 2.8
(d) 1.4

Answer 3

A-004-001-003
In a full-wave centre-tap power supply, regardless of load conditions, the peak inverse voltage (PIV) will be _____ times the RMS voltage:

(c) 2.8

Question 4

A-004-001-004
A full-wave bridge rectifier circuit makes use of both halves of the AC cycle, but unlike the full-wave centre-tap rectifier circuit it does not require:

(a) any output filtering
(b) a centre-tapped primary on the transformer
(c) diodes across each leg of the transformer
(d) a centre-tapped secondary on the transformer

Answer 4

A-004-001-004
A full-wave bridge rectifier circuit makes use of both halves of the AC cycle, but unlike the full-wave centre-tap rectifier circuit it does not require:

(d) a centre-tapped secondary on the transformer

Question 5

A-004-001-005
For a given transformer the maximum output voltage available from a full-wave bridge rectifier circuit will be:

(a) half that of the full-wave centre-tap rectifier
(b) the same as the full-wave centre-tap rectifier
(c) double that of the full-wave centre-tap rectifier
(d) the same as the half-wave rectifier

Answer 5

A-004-001-005
For a given transformer the maximum output voltage available from a full-wave bridge rectifier circuit will be:

(c) double that of the full-wave centre-tap rectifier

Question 6

A-004-001-006
The ripple frequency produced by a full-wave power supply connected to a normal household circuit is:

(a) 60 Hz
(b) 90 Hz
(c) 30 Hz
(d) 120 Hz

Answer 6

A-004-001-006
The ripple frequency produced by a full-wave power supply connected to a normal household circuit is:

(d) 120 Hz

Question 7

A-004-001-007
The ripple frequency produced by a half-wave power supply connected to a normal household circuit is:

(a) 90 Hz
(b) 60 Hz
(c) 120 Hz
(d) 30 Hz

Answer 7

A-004-001-007
The ripple frequency produced by a half-wave power supply connected to a normal household circuit is:

(b) 60 Hz

Question 8

A-004-001-008
Full-wave voltage doublers:

(a) create four times the output voltage of half-wave doublers
(b) use less power than half-wave doublers
(c) use both halves of an AC wave
(d) are used only in high-frequency power supplies

Answer 8

A-004-001-008
Full-wave voltage doublers:

(c) use both halves of an AC wave

Question 9

A-004-001-009
What are the two major ratings that must not be exceeded for silicon-diode rectifiers used in power-supply circuits?

(a) Average power average voltage
(b) Capacitive reactance avalanche voltage
(c) Peak inverse voltage average forward current
(d) Peak load impedance peak voltage

Answer 9

A-004-001-009
What are the two major ratings that must not be exceeded for silicon-diode rectifiers used in power-supply circuits?

(c) Peak inverse voltage average forward current

Question 10

A-004-001-010
In a high voltage power supply, why should a resistor and capacitor be wired in parallel with the power-supply rectifier diodes?

(a) To smooth the output waveform
(b) To decrease the output voltage
(c) To equalize voltage drops and guard against transient voltage spikes
(d) To ensure that the current through each diode is about the same

Answer 10

A-004-001-010
In a high voltage power supply, why should a resistor and capacitor be wired in parallel with the power-supply rectifier diodes?

(c) To equalize voltage drops and guard against transient voltage spikes

Question 11

A-004-001-011
What is the output waveform of an unfiltered full-wave rectifier connected to a resistive load?

(a) A steady DC voltage
(b) A series of pulses at twice the frequency of the AC input
(c) A sine wave at half the frequency of the AC input
(d) A series of pulses at the same frequency as the AC input

Answer 11

A-004-001-011
What is the output waveform of an unfiltered full-wave rectifier connected to a resistive load?

(b) A series of pulses at twice the frequency of the AC input

Question 12

A-004-002-001
Filter chokes are rated according to:

(a) reactance at 1000 Hz
(b) inductance and current-handling capacity
(c) power loss
(d) breakdown voltage

Answer 12

A-004-002-001
Filter chokes are rated according to:

(b) inductance and current-handling capacity

Question 13

A-004-002-002
Which of the following circuits gives the best regulation, under similar load conditions?

(a) A full-wave rectifier with a choke input filter
(b) A half-wave bridge rectifier with a capacitor input filter
(c) A half-wave rectifier with a choke input filter
(d) A full-wave rectifier with a capacitor input filter

Answer 13

A-004-002-002
Which of the following circuits gives the best regulation, under similar load conditions?

(a) A full-wave rectifier with a choke input filter

Question 14

A-004-002-003
The advantage of the capacitor input filter over the choke input filter is:

(a) better filtering action or smaller ripple voltage
(b) a higher terminal voltage output
(c) improved voltage regulation
(d) lower peak rectifier currents

Answer 14

A-004-002-003
The advantage of the capacitor input filter over the choke input filter is:

(b) a higher terminal voltage output

Question 15

A-004-002-004
With a normal load, the choke input filter will give the:

(a) best regulated output
(b) greatest percentage of ripple
(c) greatest ripple frequency
(d) highest output voltage

Answer 15

A-004-002-004
With a normal load, the choke input filter will give the:

(a) best regulated output

Question 16

A-004-002-005
There are two types of filters in general use in a power supply. They are called:

(a) choke output and capacitor output
(b) choke input and capacitor output
(c) choke input and capacitor input
(d) choke output and capacitor input

Answer 16

A-004-002-005
There are two types of filters in general use in a power supply. They are called:

(c) choke input and capacitor input

Question 17

A-004-002-006
The main function of the bleeder resistor in a power supply is to provide a discharge path for the capacitor in the power supply. But it may also be used for a secondary function, which is to:

(a) improve voltage regulation
(b) provide a ground return for the transformer
(c) inhibit the flow of current through the supply
(d) act as a secondary smoothing device in conjunction with the filter

Answer 17

A-004-002-006
The main function of the bleeder resistor in a power supply is to provide a discharge path for the capacitor in the power supply. But it may also be used for a secondary function, which is to:

(a) improve voltage regulation

Question 18

A-004-002-007
In a power supply, series chokes will:

(a) readily pass the DC and the AC component
(b) readily pass the DC but will impede the flow of the AC component
(c) impede the passage of DC but will pass the AC component
(d) impede both DC and AC

Answer 18

A-004-002-007
In a power supply, series chokes will:

(b) readily pass the DC but will impede the flow of the AC component

Question 19

A-004-002-008
When using a choke input filter, a minimum current should be drawn all the time when the device is switched on. This can be accomplished by:

(a) utilizing a full-wave bridge rectifier circuit
(b) placing an ammeter in the output circuit
(c) increasing the value of the output capacitor
(d) including a suitable bleeder resistance

Answer 19

A-004-002-008
When using a choke input filter, a minimum current should be drawn all the time when the device is switched on. This can be accomplished by:

(d) including a suitable bleeder resistance

Question 20

A-004-002-009
In the design of a power supply, the designer must be careful of resonance effects because the ripple voltage could build up to a high value. The components that must be carefully selected are:

(a) first choke and first capacitor
(b) the bleeder resistor and the first choke
(c) first capacitor and second capacitor
(d) first choke and second capacitor

Answer 20

A-004-002-009
In the design of a power supply, the designer must be careful of resonance effects because the ripple voltage could build up to a high value. The components that must be carefully selected are:

(a) first choke and first capacitor

Question 21

A-004-002-010
Excessive rectifier peak current and abnormally high peak inverse voltages can be caused in a power supply by the filter forming a:

(a) short circuit across the bleeder
(b) series resonant circuit with the first choke and first capacitor
(c) parallel resonant circuit with the first choke and second capacitor
(d) tuned inductance in the filter choke

Answer 21

A-004-002-010
Excessive rectifier peak current and abnormally high peak inverse voltages can be caused in a power supply by the filter forming a:

(b) series resonant circuit with the first choke and first capacitor

Question 22

A-004-002-011
In a properly designed choke input filter power supply, the no-load voltage across the filter capacitor will be about nine-tenths of the AC RMS voltage yet it is advisable to use capacitors rated at the peak transformer voltage. Why is this large safety margin suggested?

(a) Under no-load conditions and a burned-out bleeder, voltages could reach the peak transformer voltage
(b) Resonance can be set up in the filter producing high voltages
(c) Under heavy load, high currents and voltages are produced
(d) Under no-load conditions, the current could reach a high level

Answer 22

A-004-002-011
In a properly designed choke input filter power supply, the no-load voltage across the filter capacitor will be about nine-tenths of the AC RMS voltage yet it is advisable to use capacitors rated at the peak transformer voltage. Why is this large safety margin suggested?

(a) Under no-load conditions and a burned-out bleeder, voltages could reach the peak transformer voltage

Question 23

A-004-003-001
What is one characteristic of a linear electronic voltage regulator?

(a) It has a ramp voltage at its output
(b) The conduction of a control element is varied in direct proportion to the line voltage or load current
(c) A pass transistor switches from its “on” state to its “off” state
(d) The control device is switched on or off, with the duty cycle proportional to the line or load conditions

Answer 23

A-004-003-001
What is one characteristic of a linear electronic voltage regulator?

(b) The conduction of a control element is varied in direct proportion to the line voltage or load current

Question 24

A-004-003-002
What is one characteristic of a switching voltage regulator?

(a) The conduction of a control element is varied in direct proportion to the line voltage or load current
(b) The control device is switched on and off, with the duty cycle proportional to the line or load conditions
(c) It provides more than one output voltage
(d) It gives a ramp voltage at its output

Answer 24

A-004-003-002
What is one characteristic of a switching voltage regulator?

(b) The control device is switched on and off, with the duty cycle proportional to the line or load conditions

Question 25

A-004-003-003 What device is typically used as a stable reference voltage in a linear voltage regulator? (a) An SCR (b) A varactor diode (c) A junction diode (d) A Zener diode

Answer 25

A-004-003-003 What device is typically used as a stable reference voltage in a linear voltage regulator? (d) A Zener diode

Question 26

A-004-003-004 What type of linear regulator is used in applications requiring efficient utilization of the primary power source? (a) A shunt regulator (b) A series regulator (c) A constant current source (d) A shunt current source

Answer 26

A-004-003-004 What type of linear regulator is used in applications requiring efficient utilization of the primary power source? (b) A series regulator

Question 27

A-004-003-005 What type of linear voltage regulator is used in applications requiring a constant load on the unregulated voltage source? (a) A constant current source (b) A shunt current source (c) A shunt regulator (d) A series regulator

Answer 27

A-004-003-005 What type of linear voltage regulator is used in applications requiring a constant load on the unregulated voltage source? (c) A shunt regulator

Question 28

A-004-003-006 How is remote sensing accomplished in a linear voltage regulator? (a) A feedback connection to an error amplifier is made directly to the load (b) An error amplifier compares the input voltage to the reference voltage (c) A load connection is made outside the feedback loop (d) By wireless inductive loops

Answer 28

A-004-003-006 How is remote sensing accomplished in a linear voltage regulator? (a) A feedback connection to an error amplifier is made directly to the load

Question 29

A-004-003-007 What is a three-terminal regulator? (a) A regulator that supplies three voltages at a constant current (b) A regulator containing three error amplifiers and sensing transistors (c) A regulator containing a voltage reference, error amplifier, sensing resistors and transistors, and a pass element (d) A regulator that supplies three voltages with variable current

Answer 29

A-004-003-007 What is a three-terminal regulator? (c) A regulator containing a voltage reference, error amplifier, sensing resistors and transistors, and a pass element

Question 30

A-004-003-008 In addition to an input voltage range what are the important characteristics of a three-terminal regulator? (a) Maximum output voltage and minimum output current (b) Minimum output voltage and maximum output current (c) Output voltage and minimum output current (d) Output voltage and maximum output current

Answer 30

A-004-003-008 In addition to an input voltage range what are the important characteristics of a three-terminal regulator? (d) Output voltage and maximum output current

Question 31

A-004-003-009 What type of voltage regulator contains a voltage reference, error amplifier, sensing resistors and transistors, and a pass element in one package? (a) An op-amp regulator (b) A three-terminal regulator (c) A switching regulator (d) A Zener regulator

Answer 31

A-004-003-009 What type of voltage regulator contains a voltage reference, error amplifier, sensing resistors and transistors, and a pass element in one package? (b) A three-terminal regulator

Question 32

A-004-003-010 When extremely low ripple is required, or when the voltage supplied to the load must remain constant under conditions of large fluctuations of current and line voltage, a closed-loop amplifier is used to regulate the power supply. There are two main categories of electronic regulators. They are: (a) non-linear and switching (b) linear and non-linear (c) stiff and switching (d) linear and switching

Answer 32

A-004-003-010 When extremely low ripple is required, or when the voltage supplied to the load must remain constant under conditions of large fluctuations of current and line voltage, a closed-loop amplifier is used to regulate the power supply. There are two main categories of electronic regulators. They are: (d) linear and switching

Question 33

A-004-003-011 A modern type of regulator, which features a reference, high-gain amplifier, temperature-compensated voltage sensing resistors and transistors as well as a pass element is commonly referred to as a: (a) nine-pin terminal regulator (b) twenty-four pin terminal (c) regulator six-terminal regulator (d) three-terminal regulator

Answer 33

A-004-003-011 A modern type of regulator, which features a reference, high-gain amplifier, temperature-compensated voltage sensing resistors and transistors as well as a pass element is commonly referred to as a: (d) three-terminal regulator

Question 34

A-004-004-001 In a series-regulated power supply, the power dissipation of the pass transistor is: (a) the inverse of the load current and the input/output voltage differential (b) dependent upon the peak inverse voltage appearing across the Zener diode (c) directly proportional to the load current and the input/output voltage differential (d) indirectly proportional to the load voltage and the input/output voltage differential

Answer 34

A-004-004-001 In a series-regulated power supply, the power dissipation of the pass transistor is: (c) directly proportional to the load current and the input/output voltage differential

Question 35

A-004-004-002 In any regulated power supply, the output is cleanest and the regulation is best: (a) at the point where the sampling network or error amplifier is connected (b) across the secondary of the pass transistor (c) across the load (d) at the output of the pass transistor

Answer 35

A-004-004-002 In any regulated power supply, the output is cleanest and the regulation is best: (a) at the point where the sampling network or error amplifier is connected

Question 36

A-004-004-003 When discussing a power supply the_______ resistance is equal to the output voltage divided by the total current drawn, including the current drawn by the bleeder resistor: (a) ideal (b) rectifier (c) differential (d) load

Answer 36

A-004-004-003 When discussing a power supply the_______ resistance is equal to the output voltage divided by the total current drawn, including the current drawn by the bleeder resistor: (d) load

Question 37

A-004-004-004 The regulation of long-term changes in the load resistance of a power supply is called: (a) active regulation (b) analog regulation (c) dynamic regulation (d) static regulation

Answer 37

A-004-004-004 The regulation of long-term changes in the load resistance of a power supply is called: (d) static regulation

Question 38

A-004-004-005 The regulation of short-term changes in the load resistance of a power supply is called: (a) static regulation (b) analog regulation (c) active regulation (d) dynamic regulation

Answer 38

A-004-004-005 The regulation of short-term changes in the load resistance of a power supply is called: (d) dynamic regulation

Question 39

A-004-004-006 The dynamic regulation of a power supply is improved by increasing the value of: (a) the choke (b) the input capacitor (c) the bleeder resistor (d) the output capacitor

Answer 39

A-004-004-006 The dynamic regulation of a power supply is improved by increasing the value of: (d) the output capacitor

Question 40

A-004-004-007 The output capacitor, in a power supply filter used to provide power for an SSB or CW transmitter, will give better dynamic regulation if: (a) the negative terminal of the electrolytic capacitor is connected to the positive and the positive terminal to ground (b) a battery is placed in series with the output capacitor (c) it is placed in series with other capacitors (d) the output capacitance is increased

Answer 40

A-004-004-007 The output capacitor, in a power supply filter used to provide power for an SSB or CW transmitter, will give better dynamic regulation if: (d) the output capacitance is increased

Question 41

A-004-004-008 In a regulated power supply, four diodes connected together in a BRIDGE act as: (a) equalization across the transformer (b) a rectifier (c) matching between the secondary of the power transformer and the filter (d) a tuning network

Answer 41

A-004-004-008 In a regulated power supply, four diodes connected together in a BRIDGE act as: (b) a rectifier

Question 42

A-004-004-009 In a regulated power supply, components that conduct alternating current at the input before the transformer and direct current before the output are: (a) fuses (b) capacitors (c) diodes (d) chokes

Answer 42

A-004-004-009 In a regulated power supply, components that conduct alternating current at the input before the transformer and direct current before the output are: (a) fuses

Question 43

A-004-004-010 In a regulated power supply, the output of the electrolytic filter capacitor is connected to the: (a) pi filter (b) solid-state by-pass circuit (c) matching circuit for the load (d) voltage regulator

Answer 43

A-004-004-010 In a regulated power supply, the output of the electrolytic filter capacitor is connected to the: (d) voltage regulator

Question 44

A-004-004-011 In a regulated power supply, a diode connected across the input and output terminals of a regulator is used to: (a) protect the regulator from reverse voltages (b) provide an RF by-pass for the voltage control (c) provide additional capacity (d) protect the regulator from voltage fluctuations in the primary of the transformer

Answer 44

A-004-004-011 In a regulated power supply, a diode connected across the input and output terminals of a regulator is used to: (a) protect the regulator from reverse voltages