E7D: Power supplies and voltage regulators
E7D01:
What is one characteristic of a linear electronic voltage regulator?
The conduction of a control element is varied to maintain a constant output voltage
It has a ramp voltage as its output
It eliminates the need for a pass transistor
The control element duty cycle is proportional to the line or load conditions
E7D02:
What is one characteristic of a switching electronic voltage regulator?
The control device’s duty cycle is controlled to produce a constant average output voltage
The resistance of a control element is varied in direct proportion to the line voltage or load current
It is generally less efficient than a linear regulator
It gives a ramp voltage at its output
E7D03:
What device is typically used as a stable reference voltage in a linear voltage regulator?
A Zener diode
A tunnel diode
An SCR
A varactor diode
E7D04:
Which of the following types of linear regulator makes the most efficient use of the primary power source?
A series regulator
A constant current source
A shunt regulator
A shunt current source
E7D05:
Which of the following types of linear voltage regulator places a constant load on the unregulated voltage source?
A shunt regulator
A constant current source
A series regulator
A shunt current source
E7D06:
What is the purpose of Q1 in the circuit shown in Figure E7-3?
It increases the current-handling capability of the regulator
It provides negative feedback to improve regulation
It provides a constant load for the voltage source
It provides D1 with current
E7D07:
What is the purpose of C2 in the circuit shown in Figure E7-3?
It bypasses hum around D1
It is a brute force filter for the output
To self-resonate at the hum frequency
To provide fixed DC bias for Q1
E7D08:
What type of circuit is shown in Figure E7-3?
Linear voltage regulator
Switching voltage regulator
Grounded emitter amplifier
Emitter follower
E7D09:
What is the purpose of C1 in the circuit shown in Figure E7-3?
It filters the supply voltage
It resonates at the ripple frequency
It provides fixed bias for Q1
It decouples the output
E7D10:
What is the purpose of C3 in the circuit shown in Figure E7-3?
It prevents self-oscillation
It provides brute force filtering of the output
It provides fixed bias for Q1
It clips the peaks of the ripple
E7D11:
What is the purpose of R1 in the circuit shown in Figure E7-3?
It supplies current to D1
It provides a constant load to the voltage source
It couples hum to D1
It bypasses hum around D1
E7D12:
What is the purpose of R2 in the circuit shown in Figure E7-3?
It provides a constant minimum load for Q1
It provides fixed bias for Q1
It provides fixed bias for D1
It decouples hum from D1
E7D13:
What is the purpose of D1 in the circuit shown in Figure E7-3?
To provide a voltage reference
To provide line voltage stabilization
Peak clipping
Hum filtering
E7D14:
What is one purpose of a "bleeder" resistor in a conventional (unregulated) power supply?
To improve output voltage regulation
To cut down on waste heat generated by the power supply
To balance the low-voltage filament windings
To boost the amount of output current
E7D15:
What is the purpose of a "step-start" circuit in a high-voltage power supply?
To allow the filter capacitors to charge gradually
To provide a dual-voltage output for reduced power applications
To compensate for variations of the incoming line voltage
To allow for remote control of the power supply
E7D16:
When several electrolytic filter capacitors are connected in series to increase the operating voltage of a power supply filter circuit, why should resistors be connected across each capacitor?
All of these answers are correct
To equalize, as much as possible, the voltage drop across each capacitor
To provide a safety bleeder to discharge the capacitors when the supply is off
To provide a minimum load current to reduce voltage excursions at light loads
E7D17:
What is the primary reason that a high-frequency inverter type high-voltage power supply can be both less expensive and lighter in weight than a conventional power supply?
The high frequency inverter design uses much smaller transformers and filter components for an equivalent power output
The inverter design does not require any output filtering
It uses a diode bridge rectifier for increased output
It uses a large power-factor compensation capacitor to create "free" power from the unused portion of the AC cycle
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