NavigationUser loginWho's new
|
Amateur Radio Question PoolsNew! View the differences between the 2008 Extra question pool and the previous pool. Canadian Advanced Qualification Question PoolPrev 1 2 3 4 5 6 7 NextA-004-01-01 For the same transformer secondary voltage, which rectifier has the highest average output voltage? Quarter-wave Bridge Full-wave A-004-01-02 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. 2.8 5.6 l.4 A-004-01-03 In a full-wave centre-tap power supply, regardless of load conditions, the peak inverse voltage (PIV) will be _____ times the RMS voltage: 2.8 0.707 1.4 A-004-01-04 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 centre-tapped primary on the transformer a centre-tapped secondary on the transformer diodes across each leg of the transformer A-004-01-05 The output from a full-wave bridge rectifier circuit will appear to be: half that of the full-wave centre-tap rectifier the same as the full-wave centre-tap rectifier the same as the half-wave rectifier A-004-01-06 The ripple frequency produced by a fullwave power supply connected to a normal household circuit is: 60 Hz 90 Hz 30 Hz A-004-01-07 The ripple frequency produced by a halfwave power supply connected to a normal household circuit is: 60 Hz 120 Hz 30 Hz A-004-01-08 Full-wave voltage doublers: use less power than half- wave doublers use both halves of an AC wave are used only in high-frequency power supplies A-004-01-09 What are the two major ratings that must not be exceeded for silicon-diode rectifiers used in power-supply circuits? Capacitive reactance; avalanche voltage Peak load impedance; peak voltage Peak inverse voltage; average forward current A-004-01-10 Why should a resistor and capacitor be wired in parallel with power-supply rectifier diodes? To equalize voltage drops and guard against transient voltage spikes To decrease the output voltage To ensure that the current through each diode is about the same A-004-01-11 What is the output waveform of an unfiltered full-wave rectifier connected to a resistive load? A sine wave at half the frequency of the AC input A series of pulses at twice the frequency of the AC input A series of pulses at the same frequency as the AC input A-004-02-01 Filter chokes are rated according to: power loss breakdown voltage inductance and current-handling capacity A-004-02-02 Which of the following circuits gives the best regulation, under similar load conditions? A half-wave rectifier with a choke input filter A full-wave rectifier with a choke input filter A full-wave rectifier with a capacitor input filter A-004-02-03 The advantage of the capacitor input filter over the choke input filter is: improved voltage regulation lower peak rectifier currents a higher terminal voltage output A-004-02-04 With a normal load, the choke input filter will give the: greatest percentage of ripple greatest ripple frequency highest output voltage A-004-02-05 There are two types of filters in general use in a power supply. They are called: choke input and capacitor input choke input and capacitor output choke output and capacitor input A-004-02-06 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: provide a ground return for the transformer inhibit the flow of current through the supply act as a secondary smoothing device in conjunction with the filter A-004-02-07 In a power supply, series chokes will: readily pass the DC and the AC component impede the passage of DC but will pass the AC component impede both DC and AC A-004-02-08 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: placing an ammeter in the output circuit increasing the value of the output capacitor adjusting the bleeder resistance A-004-02-09 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: first capacitor and second capacitor first choke and first capacitor first choke and second capacitor A-004-02-10 Excessive rectifier peak current and abnormally high peak inverse voltages can be caused in a power supply by the filter forming a: parallel resonant circuit with the first choke and second capacitor series resonant circuit with the first choke and first capacitor tuned inductance in the filter choke A-004-02-11 In a properly designed choke input filter power supply, the filter capacitor will be about nine-tenths of the AC RMS noload voltage across the voltage; yet it is advisable to use capacitors rated at the peak transformer voltage. Why is this large safety margin suggested? Under heavy load, high currents and voltages are produced Under no-load conditions and a burnedout bleeder, voltages could reach the peak transformer voltage Under no-load conditions, the current could reach a high level A-004-03-01 What is one characteristic of a linear electronic voltage regulator? It has a ramp voltage at its output A pass transistor switches from its "on" state to its "off" state The control device is switched on or off, with the duty cycle proportional to the line or load conditions A-004-03-02 What is one characteristic of a switching voltage regulator? The conduction of a control element is varied in direct proportion to the line voltage or load current It provides more than one output voltage It gives a ramp voltage at its output A-004-03-03 What device is typically used as a stable reference voltage in a linear voltage regulator? A varactor diode A junction diode A zener diode A-004-03-04 What type of linear regulator is used in applications requiring efficient utilization of the primary power source? A constant current source A shunt current source A series regulator A-004-03-05 What type of linear voltage regulator is used in applications requiring a constant load on the unregulated voltage source? A shunt current source A shunt regulator A series regulator A-004-03-06 How is remote sensing accomplished in a linear voltage regulator? A load connection is made outside the feedback loop A feedback connection to an error amplifier is made directly to the load By wireless inductive loops A-004-03-07 What is a three-terminal regulator? A regulator containing a voltage reference, error amplifier, sensing resistors and transistors, and a pass element A regulator containing three error amplifiers and sensing transistors A regulator that supplies three voltages with variable current A-004-03-08 What are the important characteristics of a three-terminal regulator? Maximum and minimum input voltage, maximum output current and voltage Maximum and minimum input voltage, minimum output voltage and maximum output current Maximum and minimum input voltage, minimum output current and voltage A-004-03-09 What type of voltage regulator contains a voltage reference, error amplifier, sensing resistors and transistors, and a pass element in one package? A three-terminal regulator A switching regulator A zener regulator A-004-03-10 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: non-linear and switching linear and non-linear "stiff" and switching A-004-03-11 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: three-terminal regulator twenty-four pin terminal regulator six-terminal regulator A-004-04-01 In a series-regulated power supply, the power dissipation of the pass transistor is: directly proportional to the load current and the input/output voltage differential dependent upon the peak inverse voltage appearing across the Zener diode indirectly proportional to the load voltage and the input/output voltage differential A-004-04-02 In any regulated power supply, the output is cleanest and the regulation is best: across the secondary of the pass transistor across the load at the output of the pass transistor A-004-04-03 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: ideal rectifier differential A-004-04-04 The regulation of long-term changes in the load resistance of a power supply is called: analog regulation static regulation dynamic regulation A-004-04-05 The regulation of short-term changes in the load resistance of a power supply is called: static regulation analog regulation active regulation A-004-04-06 The dynamic regulation of a power supply is improved by increasing the value of: the input capacitor the output capacitor the bleeder resistor A-004-04-07 The output capacitor, in a power supply or CW transmitter, will give better dynamic regulation if: the negative terminal of the electrolytic is connected to the positive and the positive terminal to ground a battery is placed in series with the output capacitor it is placed in series with other capacitors A-004-04-08 In a regulated power supply, four diodes connected together in a BRIDGE act as: matching between the secondary of the power transformer and the filter a rectifier a tuning network A-004-04-09 In a regulated power supply, components that conduct alternating current at the input before the transformer and direct current before the output are: diodes fuses chokes A-004-04-10 In a regulated power supply, the output of the electrolytic filter capacitor is connected to the : pi filter solid-state by-pass circuit matching circuit for the load A-004-04-11 In a regulated power supply, a diode connected across the input and output terminals of a regulator is used to: provide additional capacity protect the regulator from voltage fluctuations in the primary of the transformer protect the regulator |
ARRL Amateur Radio News |