E7D Power supplies and voltage regulators; solar array charge controllers
- E7D01 (D)
How does a linear electronic voltage regulator work?
- A. It has a ramp voltage as its output
- B. It eliminates the need for a pass transistor
- C. The control element duty cycle is proportional to the line or load conditions
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| D. The conduction of a control element is varied to maintain a constant output voltage |
- E7D02 (B)
How does a switchmode voltage regulator work?
- A. By alternating the output between positive and negative voltages
- B. By varying the duty cycle of pulses input to a filter
- C. By varying the conductivity of a pass element
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| D. By switching between two Zener diode reference voltages |
- E7D03 (A)
What device is used as a stable voltage reference?
- A. A Zener diode
- B. A digital-to-analog converter
- C. An SCR
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| D. An analog-to-digital converter |
- E7D04 (B)
Which of the following describes a three-terminal voltage regulator?
- A. A series current source
- B. A series regulator
- C. A shunt regulator
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| D. A shunt current source |
- E7D05 (D)
Which of the following types of linear voltage regulator operates by loading the unregulated voltage source?
- A. A constant current source
- B. A series regulator
- C. A shunt current source
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- E7D06 (C)
What is the purpose of Q1 in the circuit shown in Figure E7-2?
- A. It provides negative feedback to improve regulation
- B. It provides a constant load for the voltage source
- C. It controls the current to keep the output voltage constant
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| D. It provides regulation by switching or “chopping” the input DC voltage |
- E7D07 (A)
What is the purpose of C2 in the circuit shown in Figure E7-2?
- A. It bypasses rectifier output ripple around D1
- B. It is a brute force filter for the output
- C. To prevent self-oscillation
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| D. To provide fixed DC bias for Q1 |
- E7D08 (C)
What type of circuit is shown in Figure E7-2?
- A. Switching voltage regulator
- B. Common emitter amplifier
- C. Linear voltage regulator
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- E7D09 (C)
How is battery operating time calculated?
- A. Average current divided by capacity in amp-hours
- B. Average current divided by internal resistance
- C. Capacity in amp-hours divided by average current
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| D. Internal resistance divided by average current |
- E7D10 (C)
Why is a switching type power supply less expensive and lighter than an equivalent linear power supply?
- A. The inverter design does not require an output filter circuit
- B. The control circuitry uses less current, therefore smaller heat sinks are required
- C. The high frequency inverter design uses much smaller transformers and filter components for an equivalent power output
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| D. It recovers power from the unused portion of the AC cycle, thus using fewer components |
- E7D11 (D)
What is the purpose of an inverter connected to a solar panel output?
- A. Reduce AC ripple on the output
- B. Maintain voltage with varying illumination levels
- C. Prevent discharge when panel is not illuminated
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| D. Convert the panel’s output from DC to AC |
- E7D12 (C)
What is the dropout voltage of a linear voltage regulator?
- A. Minimum input voltage for rated power dissipation
- B. Maximum output voltage drop when the input voltage is varied over its specified range
- C. Minimum input-to-output voltage required to maintain regulation
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| D. Maximum that the output voltage may decrease at rated load |
- E7D13 (C)
Which of the following calculates power dissipated by a series linear voltage regulator?
- A. Input voltage multiplied by input current
- B. Input voltage divided by output current
- C. Voltage difference from input to output multiplied by output current
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| D. Output voltage multiplied by output current |
- E7D14 (D)
What is the purpose of connecting equal-value resistors across power supply filter capacitors connected in series?
- A. Equalize the voltage across each capacitor
- B. Discharge the capacitors when voltage is removed
- C. Provide a minimum load on the supply
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| D. All these choices are correct |
- E7D15 (D)
What is the purpose of a step-start circuit in a high-voltage power supply?
- A. To provide a dual-voltage output for reduced power applications
- B. To compensate for variations of the incoming line voltage
- C. To prevent arcing across the input power switch or relay contacts
- D. To allow the filter capacitors to charge gradually
