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Canadian Amateur Radio Certificate - ADVANCED > 004 - Power Supplies > Flashcards

004 - Power Supplies Flashcards

1
Q

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

A

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

(b) Bridge

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2
Q

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

A

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

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3
Q

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

A

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

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4
Q

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

A

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

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5
Q

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

A

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

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6
Q

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

A

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

(d) 120 Hz

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7
Q

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

A

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

(b) 60 Hz

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8
Q

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

A

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

(c) use both halves of an AC wave

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9
Q

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

A

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

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10
Q

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

A

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

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11
Q

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

A

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

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12
Q

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

A

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

(b) inductance and current-handling capacity

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13
Q

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

A

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

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14
Q

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

A

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

(b) a higher terminal voltage output

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15
Q

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

A

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

(a) best regulated output

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16
Q

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

A

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

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17
Q

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

A

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

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18
Q

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

A

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

19
Q

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

A

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

20
Q

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

A

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

21
Q

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

A

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

22
Q

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

A

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

23
Q

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

A

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

24
Q

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

A

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

25
Q

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

A

A-004-003-003
What device is typically used as a stable reference voltage in a linear voltage regulator?

(d) A Zener diode

26
Q

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

A

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

27
Q

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

A

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

28
Q

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

A

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

29
Q

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

A

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

30
Q

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

A

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

31
Q

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

A

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

32
Q

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

A

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

33
Q

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

A

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

34
Q

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

A

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

35
Q

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

A

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

36
Q

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

A

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

37
Q

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

A

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

(d) static regulation

38
Q

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

A

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

(d) dynamic regulation

39
Q

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

A

A-004-004-006
The dynamic regulation of a power supply is improved by increasing the value of:

(d) the output capacitor

40
Q

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

A

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

41
Q

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

A

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

(b) a rectifier

42
Q

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

A

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

43
Q

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

A

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

(d) voltage regulator

44
Q

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

A

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

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