A-004 — Power supplies

Power supplies: rectifiers, filtering, regulation, switching supplies and their failure modes.

All 44 questions

• A-004-001-001 For the same transformer secondary voltage, which rectifier has the highest average output voltage?
• 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-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-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-004-001-005 For a given transformer the maximum output voltage available from a full-wave bridge rectifier circuit will be:
• A-004-001-006 The ripple frequency produced by a full-wave power supply connected to a normal household circuit is:
• A-004-001-007 The ripple frequency produced by a half-wave power supply connected to a normal household circuit is:
• A-004-001-008 Full-wave voltage doublers:
• 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-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-004-001-011 What is the output waveform of an unfiltered full-wave rectifier connected to a resistive load?
• A-004-002-001 Filter chokes are rated according to:
• A-004-002-002 Which of the following circuits gives the best regulation, under similar load conditions?
• A-004-002-003 The advantage of the capacitor input filter over the choke input filter is:
• A-004-002-004 With a normal load, the choke input filter will give the:
• A-004-002-005 There are two types of filters in general use in a power supply. They are called:
• 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-004-002-007 In a power supply, series chokes will:
• 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-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-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-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-004-003-001 What is one characteristic of a linear electronic voltage regulator?
• A-004-003-002 What is one characteristic of a switching voltage regulator?
• A-004-003-003 What device is typically used as a stable reference voltage in a linear voltage regulator?
• A-004-003-004 What type of linear regulator is used in applications requiring efficient utilization of the primary power source?
• A-004-003-005 What type of linear voltage regulator is used in applications requiring a constant load on the unregulated voltage source?
• A-004-003-006 How is remote sensing accomplished in a linear voltage regulator?
• A-004-003-007 What is a three-terminal regulator?
• A-004-003-008 In addition to an input voltage range what are the important characteristics of a three-terminal regulator?
• 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-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-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-004-004-001 In a series-regulated power supply, the power dissipation of the pass transistor is:
• A-004-004-002 In any regulated power supply, the output is cleanest and the regulation is best:
• 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-004-004-004 The regulation of long-term changes in the load resistance of a power supply is called:
• A-004-004-005 The regulation of short-term changes in the load resistance of a power supply is called:
• A-004-004-006 The dynamic regulation of a power supply is improved by increasing the value of:
• 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-004-004-008 In a regulated power supply, four diodes connected together in a BRIDGE act as:
• 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-004-004-010 In a regulated power supply, the output of the electrolytic filter capacitor is connected to the:
• A-004-004-011 In a regulated power supply, a diode connected across the input and output terminals of a regulator is used to: