Electrical and Electronics: Module 23

Module 23A: Power Supplies (Core)

Suggested time: 10 - 15 hours

Level: Intermediate

Prerequisites: Modules 1, 2, 17A

Foundational Objectives

To work safely and cooperatively with other students and handle materials in a safe manner.
To be knowledgeable and skilled with different materials and devices and their application in the electricity and electronics field.
To demonstrate the safe use and knowledge of meters and hand and power tools used in the electrical industry.
To make and interpret meter readings.
To test and evaluate the integrity of electrical and electronic components.

Common Essential Learnings Foundational Objectives

To use the appropriate vocabulary and symbols related to power supply. (COM)
To make necessary calculations and decisions related to power supply. (NUM, IL)
To develop an understanding of the limitations of technology (TL).
To use problem-solving strategies to troubleshoot power supplies. (CCT)

Learning Objectives	Notes
TRANSFORMERS
23.1 To select a suitable transformer for the required power supply. (CCT)	Using the information acquired in Module 14, determine the type of transformer required for the application. Select and test the transformer if it is being recycled from salvaged parts.

RECTIFICATION

23.2 To explain the operation of a half-wave rectifier. (COM)	Connect a diode into a circuit to provide half-wave rectification. Using a multimeter measure the output voltage. Observe the shape of the output wave using an oscilloscope. Draw the schematic diagram of a half-wave rectifier circuit.
23.3 To troubleshoot a half-wave rectifier. (CCT)	No power applied . use a multimeter to check the diode and transformer. Analyze and predict the expected results of: a shorted transformer an open transformer a shorted diode an open diode.
23.4 To explain the operation of a full-wave rectifier. (COM)	Connect two diodes and a center-tap transformer into a configuration that will provide full-wave rectification. Using a multimeter, measure the output voltage. Observe the shape of the output wave using an oscilloscope. Draw the schematic diagram of a full-wave rectifier circuit. Analyze and predict the expected results of: a shorted transformer an open transformer a shorted diode or diodes an open diode or diodes.
23.5 Troubleshoot a full-wave rectifier. (CCT, TL)	Connect four diodes in a bridge rectifier configuration to a transformer to provide full-wave rectification. Using a multimeter, measure the output voltage.
23.6 To explain the operation of a bridge rectifier. (COM)	Observe the shape of the output wave using an oscilloscope. Draw the schematic diagram of the bridge rectifier circuit taking special note of the orientation of the diodes.
23.7 Troubleshoot a bridge rectifier. (CCT, TL)	Analyze and predict the expected results of: a shorted transformer an open transformer a shorted diode or diodes an open diode or diodes.

Module 23B: Power Supplies (Core)

Suggested time: 10 . 15 hours Level: Intermediate

Prerequisite: Module 23A

Learning Objectives	Notes
FILTERING
23.8 To explain how capacitors are used in filter circuits. (TL, CCT)	Properly connect a filter capacitor to the output of an unfiltered power supply. Using an oscilloscope, observe the wave-form before and after the capacitor. Measure the voltage before and after the capacitor and note the effect on the output voltage of the power supply.
23.9 Explain the pi-filter configuration. (CCT, COM)	Properly connect two capacitors and a resistor to the output of an unregulated power supply in the configuration of a pi-filter. Using an oscilloscope, observe the wave-form before and after the pi-filter. Measure the voltage before and after the pi-filter and note the effect on the output voltage of the power supply. Replace the resistor in the above configuration with an inductor and note any change in the filtered wave-form.
23.10 To troubleshoot a defective filter. (CCT, COM)	Taking special precautions in the application and disconnection of the power source and with the use of instruments (multimeter and oscilloscope), observe the output of a power supply with a defective filter. Analyze and predict the expected results of: a) a shorted filter capacitor b) an open capacitor.
23.11 To explain and express ripple in terms of percent. (CCT, COM)	Using an oscilloscope measure the ripple of the output of a filtered power supply and calculate the percent ripple.

VOLTAGE REGULATION

23.12 To describe the action of the bleeder resistor. (IL, COM)	Analyze the schematic diagram of a power supply and explain the purpose of the bleeder resistor.
23.13 To calculate the value of a bleeder resistor. (NUM)	Calculate the value of the bleeder resistor from a given set of requirements for the power supply.
23.14 To design a simple zener diode voltage regulator. (COM, CCT)	Draw the schematic of a zener diode regulated power supply. Connect the circuit and verify the regulation of the output voltage as the input voltage is varied.
23.15 To explain the operation of a transistor regulated power supply. (CCT, COM)	Construct and analyze a circuit using a transistor and zener diode for voltage regulation.
23.16 To design a simple series feedback regulator using an operational amplifier (op-amp). (COM, CCT)	Construct and analyze the regulation of a power supply using an operational amplifier (op-amp).

Module 23C: Power Supplies (Core)

Suggested time: 10 - 15 hours Level: Advanced

Prerequisites: Modules 1, 2, 17A, 23A, 23B

Learning Objectives	Notes
FUSES and OVER-CURRENT DEVICES Refer to Module 7 for additional information
23.17 Explain the three ratings given to fuses. (COM)	Describe the ratings of a sample of fuses.
23.18 Describe the opening characteristics of a fast-blow, medium-blow and slow-blow fuse. (COM)	Using reference manuals, find the ratings for the samples in 23.17.
23.19 To identify fuses of different styles.	Associate samples of fuses with the styles available.
23.20 To select the most appropriate fuse for a given application. (CCT, IL)	Select the proper type of fuse given a set of required characteristics.
23.21 To explain the suitability of using either fuses or circuit breakers. (CCT)	List the characteristics of fuses and circuit breakers and give examples of the appropriate use of each.
23.22 To identify two types of circuit breakers. (COM, IL)	List characteristics of each type of breaker.
23.23 To describe a fuse resistor and give an application. (CCT)	Locate the fuse resistor in a schematic diagram and explain its use.
23.24 To describe how temperature affects a thermistor. (CCT)	Connect a circuit using a thermistor and measure the effect of temperature rise.
23.25 To describe how voltage affects a varistor. (CCT)	Connect a circuit using a varistor and measure the effect of change in voltage.