ECE121: Electronics (1) - Regulated Power Supply
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What percentage of electronic equipment is powered from low voltage DC supplies?

  • 85%
  • 95% (correct)
  • 75%
  • 50%

    • What is the typical AC voltage connected to a transformer in a DC power supply?

  • 220 V RMS (correct)
  • 110 V RMS
  • 440 V RMS
  • 330 V RMS

    • Which component of a DC power supply converts AC mains into low voltage DC supplies?

  • Transformer
  • Zener Diode
  • Voltage Regulator
  • Rectifier (correct)

    • What characteristics must a DC power supply provide for electronic components?

    <p>Well regulated and low noise</p> Signup and view all the answers

    What is the primary purpose of a transformer in a DC power supply?

    <p>To step down AC voltage</p> Signup and view all the answers

    Which of the following describes the role of a Zener-regulated DC power supply?

    <p>It provides voltage regulation.</p> Signup and view all the answers

    What type of voltage regulator is commonly used in integrated circuits?

    <p>Basic Linear Voltage Regulator</p> Signup and view all the answers

    What is likely NOT a requirement for a DC power supply used in electronics?

    <p>High ripple voltage</p> Signup and view all the answers

    What is the purpose of a transformer in a DC power supply?

    <p>To step down AC voltage to a lower level for DC output</p> Signup and view all the answers

    What type of rectification is provided by the diode in a DC power supply?

    <p>Full-wave rectification</p> Signup and view all the answers

    Which component is primarily used for filtering the voltage in a basic DC power supply?

    <p>Capacitor</p> Signup and view all the answers

    What distinguishes an ideal DC power supply from a real DC power supply?

    <p>An ideal power supply provides constant voltage despite changes</p> Signup and view all the answers

    How is line regulation defined in the context of voltage regulation?

    <p>The change in output voltage relative to input voltage change</p> Signup and view all the answers

    What happens to the output voltage of a real power supply when the load changes?

    <p>It changes under load or line changes</p> Signup and view all the answers

    Which of the following voltage regulation components is typically used in a Zener-regulated power supply?

    <p>Zener diode</p> Signup and view all the answers

    What is the initial function of the basic capacitor filter in a DC power supply?

    <p>To smooth out the rectified voltage</p> Signup and view all the answers

    What is the primary control element in a series linear voltage regulator?

    <p>A pass transistor</p> Signup and view all the answers

    What role does the output sample circuit play in a series linear voltage regulator?

    <p>It senses changes in output voltage.</p> Signup and view all the answers

    How does the error detector function in a series linear voltage regulator?

    <p>By comparing the sample voltage with a reference voltage.</p> Signup and view all the answers

    Which component is used to sense changes in output voltage in a series linear voltage regulator?

    <p>A resistive voltage divider</p> Signup and view all the answers

    What is the main goal of a series linear voltage regulator?

    <p>To maintain a constant output voltage</p> Signup and view all the answers

    In a series linear voltage regulator, what happens when the output voltage decreases?

    <p>The error detector activates the control element to compensate.</p> Signup and view all the answers

    What is the primary function of a zener diode in a DC power supply?

    <p>To provide a stable output voltage</p> Signup and view all the answers

    What type of circuit amplifies the difference voltage in a series linear voltage regulator?

    <p>A differential amplifier circuit</p> Signup and view all the answers

    Which power supply type is a series linear voltage regulator categorized under?

    <p>Regulated power supply</p> Signup and view all the answers

    How does the zener diode maintain a nearly constant output voltage?

    <p>By allowing input voltage variations within limits</p> Signup and view all the answers

    What determines the limitations on input voltage variation for a zener diode?

    <p>The minimum and maximum current values</p> Signup and view all the answers

    What happens to the zener current (IZ) as input voltage (VIN) changes?

    <p>IZ changes proportionally with VIN</p> Signup and view all the answers

    Under which condition does the zener diode operate effectively?

    <p>Within specified current limits</p> Signup and view all the answers

    What is one of the key characteristics of a zener-regulated DC power supply?

    <p>It provides stable reference voltages</p> Signup and view all the answers

    Which configuration of a zener diode is important for operation?

    <p>Reverse-biased configuration</p> Signup and view all the answers

    What happens to output voltage in a zener-regulated power supply when the load increases?

    <p>Output voltage remains nearly constant</p> Signup and view all the answers

    What is the maximum output voltage that the LM317 regulator can provide?

    <p>37 V</p> Signup and view all the answers

    What type of current can the LM317 provide to a load?

    <p>1.5 A</p> Signup and view all the answers

    Which component is essential for voltage adjustment in both LM317 and LM337?

    <p>Variable Resistor R2</p> Signup and view all the answers

    What can be neglected when calculating the output current for LM317 and LM337?

    <p>IADG, which is small 50 µA</p> Signup and view all the answers

    How does the output voltage range of the LM337 compare to that of the LM317?

    <p>Similar range but with only negative values</p> Signup and view all the answers

    What is the role of the external fixed resistor R1 in both LM317 and LM337 circuits?

    <p>To assist in voltage adjustment</p> Signup and view all the answers

    What will the output voltage be if R1 and R2 are set to their minimum values for the LM317?

    <p>1.2 V</p> Signup and view all the answers

    What is the function of the amplified difference voltage in a basic op-amp series regulator?

    <p>To maintain output voltage at a reference level</p> Signup and view all the answers

    What do the last two digits in the part number of a fixed voltage linear regulator indicate?

    <p>The output voltage</p> Signup and view all the answers

    Which of the following is a feature of integrated circuit voltage regulators?

    <p>They contain the reference voltage, error detector, and control unit in one package</p> Signup and view all the answers

    Which IC series is used for positive output linear regulation?

    <p>78xx</p> Signup and view all the answers

    What characterizes the 79xx series voltage regulators?

    <p>They are fixed negative voltage regulators</p> Signup and view all the answers

    What is a common application of a Zener-regulated DC power supply?

    <p>To provide a stable reference voltage</p> Signup and view all the answers

    What is the primary component of a basic linear voltage regulator?

    <p>Transistor</p> Signup and view all the answers

    Which of the following describes variable voltage integrated circuit regulators?

    <p>They do not have a fixed output voltage</p> Signup and view all the answers

    Signup and view all the answers

    Study Notes

    ECE121: Electronics (1) - Lecture 1: Regulated Power Supply

    • The course is ECE121: Electronics (1), lecture 1 covers regulated power supplies
    • The lecturer is Dr. Haitham El-Hussieny
    • The institution is Benha University, Faculty of Engineering (Shoubra)
    • The lecture date is Spring 2017

    Lecture Outline

    • Introduction to DC power supplies
    • Concept of voltage regulation
    • Zener-regulated DC power supply
    • Basic linear voltage regulator
    • Integrated circuit voltage regulators

    Introduction

    • Approximately 95% of electronic devices use low-voltage DC power supplies
    • Power sources can be batteries or AC-to-DC converters
    • Electronic components need well-regulated DC power with low noise and fast response to load changes

    Components of DC Power Supplies

    • AC (typically 220 V RMS) is passed through a transformer to lower the voltage to the desired DC output level
    • A rectifier converts AC to pulsating DC
    • A filter smooths the pulsating DC to a smoother DC voltage
    • A regulator maintains a constant DC voltage despite input or load changes

    Ideal vs. Real DC Regulated Power Supply

    • Ideal power supplies maintain a constant DC voltage regardless of input voltage or load changes
    • Real power supplies have output voltages that change with load or input variations

    Concept of Voltage Regulation

    • Line regulation is the percentage change in output voltage for a given change in input voltage
      • Line regulation = [(ΔVout / Vout) * 100%] / ΔVin (expressed in % / V)
    • Example: If the input voltage decreases by 5V and the output voltage by 0.25V, with a nominal output of 15V, the line regulation is 0.333%/V

    Load Regulation

    • Load regulation is the percentage change in output voltage for a given change in load current
      • Load regulation = [(VNL - VFL) / VFL] * 100% (expressed as a percentage, where VNL is no-load voltage and VFL is full-load voltage)
    • Example: If the no-load voltage is 12V and the full-load voltage is 11.9V, the load regulation is 0.840%

    A Zener-Regulated DC Power Supply

    • Zener diodes can be used as voltage regulators to provide stable reference voltages
    • Output voltage remains nearly constant despite input voltage changes (within limits)
    • Output voltage changes proportionally with input voltage changes, but output voltage changes stay within limits

    Basic Linear Voltage Regulator

    • Series voltage regulators use a pass transistor in series with the load
    • Output circuit senses output voltage changes
    • Error detector compares sample voltage with a reference voltage, causing the control element to compensate to maintain constant output voltage
    • Example: A resistive voltage divider, and an op-amp to adjust

    Integrated Circuit Voltage Regulators

    • IC regulators combine the reference voltage, error detector, and control units in one package
    • Types: fixed voltage (e.g., 78xx series for positive, 79xx for negative) and variable voltage (e.g., LM317 for positive, LM337 for negative)
    • The last two digits in the part number denote the output voltage (e.g., 7805 is a 5V regulator)
    • LM317 and LM337 are variable voltage regulators; external components set output voltage, allow adjustments from 1.2V to 37V

    Power Supply Project

    • Students are required to individually simulate a 12V power supply using IC regulators in Proteus and submit by a specific date.
    • Each team should simulate a variable power supply (+ve or -ve) and submit by another date

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    ECE121 Electronics (1) Lecture 1: Regulated Power Supply PDF

    Description

    This quiz focuses on the first lecture of ECE121: Electronics (1), presented by Dr. Haitham El-Hussieny at Benha University. The lecture delves into the fundamentals of regulated power supplies, including voltage regulation and the components involved in DC power supplies. Test your understanding of the concepts discussed in this essential topic for electronics.

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