Extra-Study/pages/E7D.md

E7D Power supplies and voltage regulators; solar array charge controllers

• E7D01 (D) How does a linear electronic voltage regulator work? #card
  • 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
  • D. The conduction of a control element is varied to maintain a constant output voltage
• E7D02 (B) How does a switchmode voltage regulator work? #card
  • 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
  • D. By switching between two Zener diode reference voltages
• E7D03 (A) What device is used as a stable voltage reference? #card
  • A. A Zener diode
  • B. A digital-to-analog converter
  • C. An SCR
  • D. An analog-to-digital converter
• E7D04 (B) Which of the following describes a three-terminal voltage regulator? #card
  • A. A series current source
  • B. A series regulator
  • C. A shunt regulator
  • D. A shunt current source
• E7D05 (D) Which of the following types of linear voltage regulator operates by loading the unregulated voltage source? #card
  • A. A constant current source
  • B. A series regulator
  • C. A shunt current source
  • D. A shunt regulator
• E7D06 (C) What is the purpose of Q1 in the circuit shown in Figure E7-2? #card
  • 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
  • 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? #card
  • A. It bypasses rectifier output ripple around D1
  • B. It is a brute force filter for the output
  • C. To prevent self-oscillation
  • D. To provide fixed DC bias for Q1
• E7D08 (C) What type of circuit is shown in Figure E7-2? #card
  • A. Switching voltage regulator
  • B. Common emitter amplifier
  • C. Linear voltage regulator
  • D. Common base amplifier
• E7D09 (C) How is battery operating time calculated? #card
  • 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
  • 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? #card
  • 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
  • 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? #card
  • A. Reduce AC ripple on the output
  • B. Maintain voltage with varying illumination levels
  • C. Prevent discharge when panel is not illuminated
  • D. Convert the panel’s output from DC to AC
• E7D12 (C) What is the dropout voltage of a linear voltage regulator? #card
  • 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
  • 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? #card
  • 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
  • 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? #card
  • A. Equalize the voltage across each capacitor
  • B. Discharge the capacitors when voltage is removed
  • C. Provide a minimum load on the supply
  • D. All these choices are correct
• E7D15 (D) What is the purpose of a step-start circuit in a high-voltage power supply? #card
  • 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