RADIO MECHANICS

RADIOMECHANICS

PROJECT EASEEffective and Affordable Secondary Education TECHNOLOGY AND LIVELIHOOD EDUCATION Radio Mechanics IV MODULE 1 BUREAU OF SECONDARY EDUCATION Department of Education DepEd Complex, Meralco Avenue Pasig City

PROJECT EASEEffective and Affordable Secondary Education TECHNOLOGY AND LIVELIHOOD EDUCATION Radio Mechanics IV MODULE 2 BUREAU OF SECONDARY EDUCATION Department of Education DepEd Complex, Meralco Avenue Pasig City

PROJECT EASEEffective and Affordable Secondary Education TECHNOLOGYAND LIVELIHOOD EDUCATION Radio Mechanics IV MODULE 3 BUREAU OF SECONDARY EDUCATION Department of Education DepEd Complex, Meralco Avenue Pasig City

PROJECT EASEEffective and Affordable Secondary Education TECHNOLOGY AND LIVELIHOOD EDUCATION Radio Mechanics IV MODULE 4 BUREAU OF SECONDARY EDUCATION Department of Education DepEd Complex, Meralco Avenue Pasig City

PROJECT EASEEffective and Affordable Secondary Education TECHNOLOGYAND LIVELIHOOD EDUCATION Radio Mechanics IV MODULE 5 BUREAU OF SECONDARY EDUCATION Department of Education DepEd Complex, Meralco Avenue Pasig City

PROJECT EASEEffective and Affordable Secondary Education TECHNOLOGY AND LIVELIHOOD EDUCATION Radio Mechanics IV MODULE 6 BUREAU OF SECONDARY EDUCATION Department of Education DepEd Complex, Meralco Avenue Pasig City

PROJECT EASEEffective and Affordable Secondary Education TECHNOLOGY AND LIVELIHOOD EDUCATION Radio Mechanics IV MODULE 7 BUREAU OF SECONDARY EDUCATION Department of Education DepEd Complex, Meralco Avenue Pasig City

PROJECT EASEEffective and Affordable Secondary Education TECHNOLOGY AND LIVELIHOOD EDUCATION Radio Mechanics IV MODULE 8 BUREAU OF SECONDARY EDUCATION Department of Education DepEd Complex, Meralco Avenue Pasig City

Radio Mechanics Fourth Year Module 1 The Starting Point (Fundamentals of Electronics)What this module is about Electronics is one of the most interesting and rewarding fields of study. It offers many opportunities toanyone who gets into it. Do you know somebody who engaged in this field? How about you? Do you want toengage in this endeavor? Engaging in electronics is sometimes frustrating, but knowledge of basic electronicswould be of great help. This module will guide you in learning the fundamentals of electronics. Following aresome of the interesting topics: -Ohm’s Law -Power Law -Sources of Electricity -Alternating Current (AC) and Direct Current (DC)What you are expected to learn After studying this module, you should be able to do these: 1. State the relationship of voltage, current, and resistance. 2. Learn the formulas of Ohm’s Law and Power Law. 3. Find the unknown values of voltage, current, resistance and power. 4. Describe the different sources of electricity. 5. Differentiate alternating current (AC) from direct current (DC).How to learn from this module In order to gain maximum benefit from this module, you have to follow carefully all the given instruc-tions. 1. Each part of this module will prepare you for the next part, be sure to work on each activity. 2. You must work through this module in sequence as the contents are presented. 1

3. Following shortly is a pretest. Do the test and check your answers by comparing them with the key to answers given at the last part of this module. Do not look at the key to answer page unless you have completed answering the test. 4. After reading and understanding each lesson, you have to do the given activity and answer the self-check to determine whether you understood what you have read. 5. Posttest is provided at the end. You must answer it and should get a score of at least 80% in order to move on to the next module. If you get lower, you have to go through the module again particularly on the part wherein you have committed an error. At this momemnt, try to answer the pretest. This will enable you to find out what you already knowand what you still need to know about the Fundamentals of Electronics. Good luck!Reminder: Be honest in answering and checking the test questions. Remember that you are studying by yourself,your learning totally depends on you.PRETESTI. Matching TypeDirections: Column A describes and interprets the meaning of the group of words in Column B. MatchColumnA with Column B. Write your answer on the blank before each number. ColumnA Column B____ 1. Voltage, current and resistance are related. power____ 2. When one quantity increases, the other one inversely proportional friction also increases. Ohm’s Law____ 3. Movement of free electrons is concerted. electricity____ 4. It is invisible force that produces heat, light and electromagnetism alternating current motion. chemical action____ 5. It utilizes certain materials that produce thermionic emission directly proportional voltage when made to vibrate. piezo-electric____ 6. Increase in one quantity decreases the other direct current current quantity. voltage____ 7. The changing magnetic field produces current.____ 8. Amplitude varies while changing polarity.____ 9. This is a type of current that flows in only one direction. 2

____ 10. Voltage is produced due to chemical reaction frequency between two different metals immersed in resistance electrolyte. photo-electric nuclear____ 11. The opposition to the flow of electric current. volt____ 12. Production of voltages when certain materials ampere emit their electrons and are exposed to light under certain conditions.____ 13. Number of times per second a cycle occurs____ 14. Work is done at a particular rate.____ 15. What is the basic unit of current.II. Problem Solving1. Calculate the voltage necessary to drive a current of 0.5 ampere through a resistance of 1,000 ohms.2. Calculate the power in a circuit where the source of 100 volts produces 4 amperes current in a 25-ohm resistance.3. What should be the value of a resistor to be connected in a circuit supplied with 24 volts in order to produce current of 0.5 ampere? Lesson 1 Voltage, Current, and Resistance (Ohm’s Law) Ohm’s Law shows the relationship of voltage, current, and resistance . It involves circuit analysis suchas finding unknown values of resistance, current and voltage. Ohm’s Law states that current flowing in a closedelectric circuit is directly proportional to the applied voltage and inversely proportional to the circuit resistance.This law was formulated by George Simon Ohm, a German scientist. Following are terms that relates to Ohm’slaw: Directly proportional means when one quantity increases the other quantity also increases. Example: In a circuit with a high voltage supply, the current flow in the said circuit is large. Inversely proportional means when one quantity increases the other quantity decreases. Example: In a high voltage circuit supply producing a large amount of current, circuit resistance is low. Expressed simply, if the supply of voltage in a circuit is high, it produces a large amount of current andresistance is presumed to be low. 3

For a better understanding of this lesson, knowledge of the meaning of the three basic electricalquantities, namely voltage, current ,and resistance is necessary.Voltage - An electrical force that moves electrons or charges to produce current. - A letter symbol of E or V. - Volt as its basic unit (v). - Can be measured by an instrument called voltmeter.Current - It is the concerted movement of free electrons in conductors. - Its letter symbol is I. - Its basic unit is ampere (A). - It is measured by an instrument, the ammeter.Resistance - Is the opposition to the flow of electric current. - Its letter symbol is R. - Its basic unit is ohm (represented by the Greek letter Omega, Ω. - It can be measured by an instrument called ohmmeter.Self-check:1. What is voltage? current? resistance?2. What letter symbol represents voltage, current and resistance respectively?3. What is the unit of measuring voltage, current and resistance respectively?4. What is the relationship between voltage and current? between current and resistance? between voltage and resistance?5. What is meant by directly proportional? inversely proportional? Lesson 2 Ohm’s Law and Electrical Power Formulas Ohm’s law states the relationship of voltage, current and resistance. It is one of the most essential lawgoverning electronic theories and principles. Knowledge of ohms law is a must for people engaged in the fieldof electronics. It involves circuit analysis such as finding unknown values of voltage, current and resistance.Ohm’s law states that the higher the voltage, the larger the current and the higher the resistance, the 4

lower the current. Their relationship is represented in the following equation: I = E R Where: I - is the current flow (in ampere) E- is the voltage (in volt) R- is the resistance (in ohm Ω )The three basic electrical quantities are defined below:Voltage = Current x Resistance E=IXRCurrent = Voltage / Resistance I = E / R or E RResistance = Voltage / Current R = E/I or E ITo keep the three formulas fresh in your mind, use the magic circle or magic triangle as your memoryguide, as follows: Horizontal Line E E IR IR Vertical Line In using the foregoing guide, the horizontal line represents the division process, and the vertical line, themultiplication process. Suppose you want to find out the unknown value of voltage (E), just cover letter E andthe remaining letters are I (current) and R (resistance) with a vertical line in between indicating the multiplica-tion process. Thus, E = I / R. Likewise, if you want to find the unknown value of resistance (R) cover letter R.The remaining letters are E and I with a horizontal line in between, indicating the division process. Thus, R = E/ I. The same procedure is applied if you want to find the unknown value of current (I). Power (P) is the rate of doing work. Electric power is the rate at which electrical energy can bedelivered to an electrical consuming device. The measuring unit of electric power is the watt. When multipliedby 1,000 is called kilowatt. Thus, one thousand ( 1,000) watts is one (1) kilowatt.1000 watts = 1 kilowatt 5

Power = Current x Voltage P = I x E This is the basic formula in determining electric power.Through Ohm’s law, one can derive other formulas in determining the extent of electrical power. P = E2 R P = I x E; by Ohm’s law I = E/RSubstituting E/R for I, thus; P = E/R x E; by multiplication, E x E is E2Then, P = E2 / R - this formula is derived from the basic formula.Another formula which can be used to determine electrical power is, P = I2 x RFrom the basic formula: P = I x E ; by Ohm’s Law, E = I x RSubstituting IR for E, thus P = I x IR; by multiplication, I x I is I2Then, P = I2 x R . This formula was also derived from the basic formula. Now that you have gone through the different aspects of Ohm’s Law and power formulas, you arenow ready for the next lesson which requires their application in solving simple problems. However, beforeproceeding, try to measure what you have learned by doing the activity and answering the questions in the self-check section.Self-check1. What formula are you going to use if you want to determine the unknown value of voltage? current? resistance?2. What power formula are you going to apply when the resistance and current in a circuit are known?3. What power formula is used when in a circuit the voltage supply and the resistance are known?Activity 1 EI (v) (A) Inside the small circle are the power and the basic electricalquantities. Write the formula for each quantity on the space provided RPfor the purpose. (Ω) (w) 6

Lesson 3Solving Unknown Values of Voltage, Current, Resistance and Power You have just learned the different formulas used in Ohm’s law and electrical power. In the precedinglesson, you learned also that the basic knowledge of Ohm’s law and power law is essential to people whowant to engage in electronics. Circuit analysis is always associated. It is the first step in a special circuit designand analysis. In learning the unknown values of voltage, current, resistance and electric power, study the followingexamples:Voltage: A. Current = 5 amperes Resistance = 20 ohms Voltage = ?Since voltage is unknown, use this formula: E = I x R; substituting the values of I and R = 5 A x 20 Ω E = 100 voltsB. current R = 10 Ω I = 10 A E?In the circuit above, voltage (E) is unknown. Thus, the formula is: E = I x R; substituting the values of I and R = 10 A x 10 Ω = 100 volts C. Asource of voltage produces current of 2 amperes through a resistance of 15 ohms. How much is the applied voltage? 7

The problem asks the value of the applied voltage, hence, the formula for finding the unknown voltageis used. E = I x R; substituting the given values of I and R = 2 A x 15 Ω = 30 volts Current: A. Voltage = 120 volts Resistance = 30 ohms Current = ? This time, the current is unknown, hence, use this formula for finding current: I = E/R, susbstituting the given values of E and R = 120 v 30 Ω = 4 amperesB. E=50 volts R = 10 Ω I=? From the above circuit, current (I) is unknown, hence, the formula you are going to use is; I = E/R; by substituting the values of E and R from the given formula; = 50 v 10 Ω = 5 amperes C. A heater with a resistance of 40 Ω is connected across a 120-volt power source. How much is the current? The problem asks the amount of current driven by a 120-volt power source, thus, we use this formulafor finding unknown current: I = E ; substituting the values of E and R from the given formula, we have R 8

= 120 40 Ω=3AResistance: A. Voltage = 100 volts Current = 4 amperes Resistance = ?At the moment, resistance is unknown, hence use this formula: R = E / I ; by substituting the values of E and I from the given formula = 100 V 4A = 25 Ω I=3A R=?B. E=24 voltsIn the circuit above, resistance (R) is unknown, so the formula used is R = E/I; substituting the values of E and I from the given formula = 24 V 3A =8Ω C. How much resistance allows 24 A current driven by a 12-volt source? 9

The value of resistance (R) is unknown in the problem. The formula we are going to use is as follows: R = E / I; by substituting the values of E and I from the given formula; = 12V 24 A = 0.5 ΩElectrical Power: 1. A bread toaster takes 5A from the 220-volt power source. How much power is used? Given: Current (I) = 5 A Voltage (E) = 220 V Power (P) = ? Formula : P = I x E; substituting the values of I and E = 5 A x 220 V = 1,100 watts 2. Calculate the power in a circuit where a source of voltage produces 3 amperes of current in a 50-ohm resistance. Given: Current = 3 A Resistance = 50 Ω Power = ? Formula: P = I2 x R; substituting the values of I and R from the given formula = (3A)2 x 50 Ω = 3 x 3 x 50 = 450 watts 3. How much is dissipated by a 2-ohm resistor with 10 volts across it? Given: Resistance = 2 Ω Voltage = 10 V 10

Power = ? Formula: P = E2 / R; substituting the values of E and R = (10V) 2 = 10 x 10 2Ω 2 = 100 2 = 50 wattsActivity 2 Below are exercises numbered 1-10. Write the values of voltage (E), current (I), resistance (R), andpower (P) in the empty squares. EXERCISES 1 2 3 4 5 6 7 8 9 10Voltage 100 24 35 200 100 60 50 12(in volts)Current 5 6 5 10 8 20 2(in ampere)Resistance 10 25 7 40 10 5 6(in ohm)Power 250 400 144 2,000 250 640 720 1,000(in watt)Self-check1. What power formula are you going to use when the values of current and resistance are given?2. What should be the power formula if voltage and resistance are given?3. The voltage of a resistor is 50 volts. The current flowing through it is 2 amperes. What is the value of the resistor? 11

Lesson 4 Sources of Electricity Through the ages, man experimented on different methods of producing electricity. He applied hisscientific know-how to make electric current work. Electricity is an invisible force or energy that produces heat as in the flat iron, electric range, andsoldering iron; light as in lamps and bulbs; and motion as in motors. This wonderful action of electricity makesalmost everything possible. All materials have changes in their atoms, but to do useful work, these charges must be separated for apotential difference that can make current flow. Some of the most common methods of producing electricaleffects are listed below:1. Friction - In this method, certain materials are rubbed against each other to produce charges. Electricity produced through this method is static electricity, which is usually used in laboratories and in research work.2. Photoelectric - In this method, certain materials emit their electrons when they are exposed to light under right conditions. Some of these materials are selenium, cesium, and silicon. The electricity produced bythis method is utilized in photo diodes, photo transistors, photo cells, and many more.3. Piezo-electric - This method uses certain materials, which when made to vibrate, produce voltage. Electricity produced by this method is used in crystal microphones and crystal pick-ups, among others.4. Thermionic emission - This method utilizes materials that release electrons when heated enough. The emitted electrons can be controlled to provide useful applications of electric current. This method is used in operating electron tubes and cathode ray tubes.5. Chemical action - In this method, two different metals are immersed in electrolyte. Chemical reaction between them occurs thus producing voltage. This method is used in dry cells and batteries.6. Electromagnetism - Electricity and magnetism are closely related. Any moving charge has an associated magnetic field, and any changing magnetic field can produce current. This is made possible when a conductor, such as coil of wire rotates in a magnetic field. This method is used in operating generators and alternators, the sources of commercial electricity.7. Nuclear method - In this method, there is a breaking up of atomic structure of some elements, thus releasing a great amount of energy. This method is utilized in nuclear power plants. 12

Activity 31. Visit a battery shop and ask the owner to allow you to observe the processes involved in making batteries (storage batteries in particular). List down all the processes in proper order.2. List down also all the materials used in making storage batteries.Self-check:1. What does electricity produce?2. What is the source of commercial electricity in our country?3. Enumerate at least five (5) electronic devices, instruments and appliances , using photoelectricity as power source. Now that you know the different sources of electricity , you have performed your activity and you haveanswered the questions given in the self-check properly, you may now proceed to the next lesson. Lesson 5 Alternating Current and Direct Current In your study about the different sources of electricity in the preceding lesson, you learned that electro-magnetism is one of the most common. Considering the fact that it was produced by generators and alterna-tors, it is also the source of commercial electricity. This important source accounts for most of the electricalpower used in homes and industry. Electricity produced is either alternating current (AC) or direct current(DC). Alternating current (AC) is a type of current that reverses its polarity and direction regularly (at theinstant, it is positive and the next instant, it is negative). In other words, it undergoes a cycle. Alternating currentcan have 60 cycles per second (60 cps), also known as its frequency, which is expressed in hertz. Thus,alternating current (AC) has a frequency of 60 hertz. Alternating current is produced byAC generators. 13

Features and Characteristics of Alternating Current -Varies in amplitude (from minimum to maximum value) while changing polarity. -Can be stepped up or down by a transformer.Applications of Alternating Current1. Alternating current is used in unlimited extent for lighting purposes, both indoor and outdoor.2. It is used in industries and establishments to operate various machines.3. It is used at home to operate appliances run by motors.4. It is also for commercial electrical power distribution.5. It is likewise used as input signals in amplifier circuits. Direct Current (DC) is a type of current that flows in only one direction. It is produced from cells onbatteries and AC generators. Below is a wave form of direct current. + 0 - DC WaveformFeatures and Characteristics of Direct Current-Fixed in polarity (positive or negative)-Steady or varied in amplitudeApplications of Direct Current1. DC is employed in transportation to operate engines.2. DC is used to operate portable appliances such as the radio, TV and karaoke.3. Used as electrode voltages of active devices in electronic circuits.Activity 4 List down all your electrical and electronic appliances at home and identify their supply voltage,alternating current voltage (ACV) or direct current voltage ( DCV). 14

Self-check:Directions: Answer the following questions:1. What is the difference between alternating current (AC) and direct current (DC)?2. What are the applications of direct current? the alternating current?3. What are the features and characteristics of direct current? the alternating current?LET’S SUMMARIZE z Ohm’s law states the relationship of voltage, current and resistance. In an electric circuit, current is directly proportional to the applied voltage and inversely proportional to the circuit resistance. z The ohm’s law formulas are as follows: I = E/R, for finding unknown current E = I x R; for finding unknown voltage R = E/I; for finding unknown resistance z The electrical power formulas are as follows: P=IxE P = I2 x R P = E2/R z The foregoing formulas are used to determine electric power consumed by electronics / electrical appliances when voltage, current, and resistance are known. z The sources of electrical energy are friction, photoelectric, piezo-electric, thermionic emission, chemical action, electromagnetism and nuclear. z Electricity produced by different sources is either alternating current (AC) or direct current (DC). Alternating current periodically changes its polarity and direction while direct current flows in one direction only.POSTTESTI. Directions: Write the word or word group that best answers each statement on the blank provided for the purpose. _____________ 1. It is the rate of doing work. _____________ 2. The rate or number of times per second that a cycle occurs. _____________ 3. It states the relationship of voltage, current, and resistance. _____________ 4. It utilizes certain materials which when made to vibrate produces voltage. _____________ 5. It is the concerted movement of free electrons. _____________ 6. It is an invisible force that produces heat, light, and motion. 15

_____________ 7. Atype of current that varies in amplitude while changing polarity._____________ 8. It is the opposition to the flow of electric current._____________ 9. It is the basic unit for measuring electric current._____________ 10. It is a type of current that flows only in one direction.II. Problem Solving1. What should be the value of a resistor to be connected in a circuit supplied with 12 volts in order to produce a current of 0.2 ampere?2. What is the power consumed by a bread toaster that is connected to a 220-volt source when a current of 5 amperes flow through it?3. Determine the current flow in a circuit when a voltage source of 24 volts is applied across a resistance of 8 ohms.KEY TO ANSWERSPretest PosttestI. Multiple Choice I. Identification1. Ohm’s law 1. power2. directly proportional 2. frequency3. current 3. Ohm’s law4. electricity 4. piezo-electric5. piezo-electric 5. current6. inversely proportional 6. electricity7. electromagnetism 7. alternating current8. alternating current 8. resistance9. direct current 9. ampere10. chemical action 10. direct current11. resistance12. photo-electric II. Problem Solving13. frequency 1. 60 ohms14. power 2. 1, 100 watts15. ampere 3. 3 amperesII. Problem Solving1. 500 volts2. 400 watts3. 48 ohms 16

Radio Mechanics Fourth Year Module 2 Strike While the Iron is Still Hot (Soldering Techniques)What this module is about Every electronic technician should know the rules on how to solder properly. The importance of doinga good soldering job that can contribute to the normal operation and service of the radio receiver, TV receiveror other electronic equipment, and project or kit. About 90% of all kit assembly and service problems relateto poorly soldered connections, particularly on printed circuit board. This module guides readers in the properway of soldering wire or component lead to the PCB. Moreover, it provides soldering rules, recommends thecorrect wattage of soldering iron for PCB, selection of solder and soldering precautions. At the end of this module, you should be able to do the following:1. Learn the different soldering techniques.2. Explain the correct tinning procedure of soldering iron, type of soldering lead and characteristics of a good solder.3. Perform an acceptable soldering job.How to learn from this module Here are some tips on how to use this module. This will guide you in learning the different lessons. I’msure you will find this very helpful as you read it.1. Read the objectives so you will know what you expect to learn from this module.2. Be sure to work on each activity because each activity prepares you for the next.3. Answer the pretest before going over the module to determine what you already know about the topics. Use the key to correction at the end of this module to check your answers, but do not do this only after completing the module.4. Always answer the self-check portion after each activity to determine whether you understood what you have read.5. Read the lessons again if you were not able to answer the questions correctly. 1

Before going through this module, try to answer the succeeding pretest. This will enable you to find outwhat you already know and what you still need to know about soldering techniques. Good luck!PRETESTDirections: Read each statement carefully and write the letter of the best answer on the blank before eachnumber._____ 1. The ideal wattage of soldering iron for beginners. a. 100 watts b. 30 watts c. 40 watts d. 60 watts_____ 2. The best type of soldering lead used in soldering components. a. 40/60 b. 60/40 c. 30/70 d. 50/50_____ 3. Normally used to hold components and serves as heat sink. a. diagonal cutter b. mechanical plier c. long or needle nose plier d. electrical plier_____ 4. Tool used in desoldering of components. a. brush b. flux remover c. file d. desoldering pump_____ 5. Cleaning supply needed in soldering. a. flux remover b. file c. sandpaper d. desoldering adaptor Did you fare well? If not, don’t worry. Anyway you will be answering the same set of test after youhave studied all the lessons in this module. By that time you shall have been able to answer all the questionscorrectly. 2

Take note, if you need any assistance in carrying out the different activities, don’t hesitate to ask thehelp of your teacher. For enrichment, read more about the topic from books which you will borrow from your school or anypublic library. Lesson 1 Soldering Tools and Materials In large and heavy metal work, welding is used in joining metals permanently. In electronics work,soldering is used to join pigtails of components, transistor leads, IC pins and among others. Soldering is theprocess of heating materials, and joints to be soldered and applying solder on the heated joints to ensurepermanent connection. The materials used in this process are soldering iron 30 to 35 watts for transistors or IC; soldering gun100 to 140 watts for chassis work, soldering tip-pretin new heating it and melting solder around heated tip;sponge to damp off extra solder of tip; re-wet every now and then. Solder resin core (does away with usingsoldering paste; 60% tin and 40% lead, 60:40).Soldering Tools1. Long or needle nose pliers hold components and serve as heat sink.2. Side or diagonal cutter which cuts excessive length of component leads, pares or strips off wire ends.3. Cleaning supplies such as flux remover which is used with brush or spray.4. Desoldering tools such as desoldering pump.Activity 1Soldering IronAssemblyMaterials Needed:1 handle (wood)1 filament tube holder1 soldering iron filament 30w1 soldering tip 3

1 AC cord with plug1 electrical tapeProcedure:1. Prepare the needed materials.2. Insert the filament tube holder into the wood handle as shown in figure 1 below.3. Insert the soldering iron filament inside the tube holder.4. Connect the AC cord with a plug to the soldering iron filament.5. Be sure to use electrical tape for the two joints which are connected to 220 VAC.6. Insert the soldering tip 30w to the soldering iron filament.7. The soldering iron is now ready for testing.Self-check:1. What is the purpose of soldering?2. How do we assemble soldering iron?3. How many watts does a soldering iron use for transistor work?4. What is the power rating in watts of a soldering gun used for chassis work?5. What possible problems do you encounter in this activity? Lesson 2 Characteristics of a Good Solder1. Clean the material or joint to be soldered. See that the solder does not stick to dirty joints or surfaces.2. Heat the joint or part to be soldered with the tip.3. Apply the solder on the part or joint to be soldered, not on the tip.4. Once the solder melts and flows around ( some flows on tip) remove the iron tip.5. Avoid disturbing the solder as it cools off. a. Do not apply heat longer than necessary (not more than 5 seconds in 1 spot). b. Prolonged heat can ruin components including the foil of PCB. c. If possible, keep the iron at a 300 to 400 angle to the point. 4

d. Apply only enough solder to coat the joint and circuit board pad. e. Avoid sharp peaks “bridges” between foils.6. Use heat sink whenever possible.7. Use soldering iron 30 watts and 60 by 40 soldering lead.Activity 2 Tinning of the Soldering IronMaterials Needed:1 soldering iron 30 w1 sand paper # 2401 flat file1 wire brush1 philips screwdriverProcedure:1. To ensure maximum heat to the tip of the soldering iron, it must always be properly tinned.2. Use sandpaper or wire brush in tinning the soldering tip of iron.3. For gold plated tips, use sponge, instead of a file or wire brush to avoid destroying the soldering tip.4. Be sure that the soldering tip is always pitted. Use a screwdriver to tighten the screw. Component side Horizontally Vertically mounted mountedPCB Foil side Soldering lead Soldering tip Soldering and Tinning 5

Activity 3Soldering of Components on PCBMaterials:1 universal PCB20 assorted resistors1 meter soldering lead, 60:401 soldering iron1 extension cord 220 VProcedure:1. Mount all the resistors on the PCB board as shown below. Follow the correct mounting procedure. • •• • • •• • • •• • • •• • • •• • • •• • • •• • • •• • • •• • • •• • • •• • • •• •2. One at a time, solder the resistor properly.3. Use at least 5 seconds in soldering every joint to avoid damage on PCB foil.4. Do not leave solder nuggets that can provide nuggets or bridges between foils.5. Be sure to cut all excess wire to avoid short circuits.Self-check:1. What is the composition of the most commonly used soldering lead?2. How do you clean or tin a tip when soldering?3. Why must the material or joint to be soldered must be cleaned very well before soldering?4. What materials are needed in tinning? 6

Lesson 3 Acceptable Soldering Jobs Always remember to keep the soldering iron tip clean. Wipe often on a wet sponge or cloth, thenapply the solder to it to give the entire tip a wet look. This tinning process protects the tip and enables you tomake good connections. When the solder tends to “ball” or does not stick to the tip, the tip needs to be cleanedand re-tinned. Use resin core radio - type solder (60:40 or 50:50 tin lead content) for all soldering.Soldering A Connection1. Position the circuit board with the plain side up (not the foil side). Soldering iron tip2. Apply only enough solder to wet both tip and the connection thoroughly. SolderSolderingiron tip3. Let the connection harden before moving the wire. The connection should be smooth and bright. 7

4. Check the connection. Poor connections look crystalline and grainy as the solder tends to blob. Heat the connection if it does not look smooth and bright.1. Position the circuit board with the plain side Push down (not the foil side) up. here2. Hold the resistor by the body as shown, and bend the leads straight down.3. Push the leads through the holes at the proper location on the circuit board. The end with color bands may be positioned either way.4. Press the resistor against the circuit board. Then bend the leads outward slightly to hold the resistor in place.Soldering a Connection1. Place the soldering tip against both the lead and the circuit board foil. Heat both for 2 to 3 seconds. Soldering iron Component lead Foil Circuit Board 8

2. Then apply the solder to the other side of the connection. NOTE: Let the heated lead and the circuit board melt the solder. Soldering iron Solder Foil3. As the solder begins to melt, let it flow around the connection. Then remove the solder and the iron and let the connection cool.4. Hold the lead with one hand while cutting off the excess lead length close to the connection. This keeps you from being hit in the eye by the flying lead.Checking Connection Solder flows outward Soldering iron and gradually blends positioned Be sure the solder makes a good electric con- with the foil and lead. correctly.nection. When both the lead and the circuit board foil areheated at the same time, the solder will flow onto the lead Foiland the foil evenly. The solder will then make a goodelectrical connection between the lead and the foil. When the lead is not heated sufficiently, the solder Solder does not flow ontowill not flow onto the lead as shown in the picture. lead. A dark bead sur-Reheat the connection and, if necessary apply a small amount rounds and insulates theof additional solder to obtain a good connection. lead from the connection. Burned rosin Foil Soldering iron positioned incorrectly.9

When the foil is not heated enough, the solder will blob on the circuit board as shown. Reheat theconnection and, if necessary, apply a small amount of additional solder to obtain a good connection.Solder appears to Soldering iron posi-flow inward and sit tioned incorrectly.on top of the foil. Burned rosin Foil Be sure you did not make any solder bridges. Due to the small foil area around the circuit board holesand the small areas between foils, you must use utmost care to prevent solder bridges between adjacent foilareas. A solder bridge between two adjacent foils. A solder bridge may occur if you accidentally touch an adjacent connection. If you use too muchsolder or “drag” the soldering iron across other foils as you remove it from the connection. Always take a goodlook at the foil area around each lead before you solder it. Then, when you solder the connection, make surethe solder remains in this area and does not bridge to another foil. This is important when the foils are small andclose together. How the connection should appearPrinted Circuit Desoldering It is sometimes necessary to remove a defective part from a printed circuit board. This can be difficultto do when the part has several leads. Several tools and aids have been developed to make the job easier.There are two popular vacuum type tools for this job. The vacuum desoldering pencil melts the joints, and then 10

the bulb is released to draw the solder off of the board. Vacuum bulb Desoldering pencil After all the leads have been desoldered, the part can be removed. A separate vacuum desolderingbulb can be used with a separate soldering pencil to accomplish the same job. Some technicians prefer to heat all the connections of a component at the same time. This will alsoallow removal of the part. Special desoldering tips are available to accomplish this. Different tip styles areneeded for the various transistor and integrated circuit parts. Yes, another technique is to use finely braided wire.Self-check:1. What precautions should be observed to avoid “bridges” between foils?2. What precautions should be observed to avoid damage to the foil on PCB?3. What is the effect of leaving solder nuggets on PCB?4. Why is there need to practice soldering? 11

LET’S SUMMARIZE To develop accurate soldering, be sure the solder made a good electric connection. When both thelead and the circuit board foil are heated at the same time, the solder will flour onto the lead and the foil evenly.The solder will then make a good electrical connection between the lead and the foil. When the lead is notheated sufficiently, the solder will not flow onto the lead. Reheat the connection and if necessary apply a smallamount of additional solder to obtain a good connection.POSTTESTDirections: Read each statement carefully and write the letter of the best answer on the blank before eachnumber._____ 1. The ideal wattage of soldering iron for beginners. a. 100 watts b. 40 watts c. 30 watts d. 60 watts_____ 2. The least type of soldering lead used in soldering components. a. 30-70 b. 40-60 c. 50-50 d. 60-40_____ 3. Tool used in desoldering of components. a. flux remover b. file c. sandpaper d. desoldering pump_____ 4. Tool used to hold components and serve as heat sink. a. long or needle nose plier b. electrical plier c. diagonal cutter d. mechanical plier_____ 5. Cleaning supply needed in soldering. a. flux remover b. file 12

c. sandpaper d. desoldering adaptorKEY TO CORRECTIONPretest1. b2. b3. c4. d5. aPosttest1. c2. d3. d4. a5. a 13

Radio Mechanics Fourth Year Module 3 Use me Up Before You Go Go (Electronic Handtools and Test Instruments)What this module is about Do you know that practically all equipment need to be tested and measured? Common troubles ofequipment cannot be identified without the use of tools and test instruments. This module was written to helpdetermine problems and troubles that may arise from time to time as we continue studying electronics.What you are expected to learn When you have completed this module, you should be able to do the following:1. Identify commonly used tools and electronic test instrument.2. Explain the use of tools and test instruments.How to learn from this module Here are tips on how to use this module. These will guide you in studying the different lessons. I’m sureyou will find these very helpful as you read through.1. Read the objectives so you will know what you expect to learn from this module.2. Be sure to work out each activity because each part prepares you for the next.3. Answer the pretest before you go through the module to determine what you already know about the content. Use the key to correction at the back to check your answers but do this only after completing the module. Always answer the self-check after each activity to determine whether you understood what you read.4. Read the lesson again if you were not able to answer the question correctly. Before going through this module, try to answer the pretest. This will acquiant you with electronichandtools and test equipment. Good luck! 1

PRETESTDirections: Read each statement carefully and choose the letter of the best answer. Write it on the blankbefore each number._____1. Use to cut soft wires and component parts. a. long nose pliers b. diagonal cutters c. mechanical pliers d. electrical pliers_____2. It removes the insulator from the hook up wire. a. soldering aid b. soldering iron c. wire stripper d. desoldering tool_____3. A tool used to solder and unsolder the components on a printed circuit board. a. soldering gun b. soldering iron c. heat sink d. low wattage soldering pencil_____4. An instrument used to measure voltage. a. ammeter b. voltmeter c. ohmmeter d. watt meter_____5. A handtool used in soldering high wattage equipment. a. soldering lead b. soldering iron c. soldering pencil d. soldering gun_____6. An instrument used in measuring current. a. ammeter b. ohmmeter c. voltmeter d. wattmeter 2

_____7. What does V.O.M. mean? a. volt ohmmeter b. volt ohm milliameter c. voltage ohmmeter d. ammeter_____8. An instrument used in measuring resistance. a. voltmeter b. wattmeter c. ohmmeter d. ammeter_____9. A handtool used in desoldering components. a. long nose pliers b. diagonal cutter c. electrical pliers d. soldering pump_____10. It must be observed when measuring DC voltage and DC current. a. negative b. positive c. polarity d. meter Are you familiar with the different electronic handtools and test instruments? If not, you still have thechance to know it because as we go along, you are going to use all those tools and instruments. Lesson 1 Commonly Used Tools and Electronic Test Instruments Special tools and various test instruments were developed as a result of the problems encountered inlocating, repairing, and replacing worn-out electronic parts. However, tools alone do not enable the technicianto service or repair electronic equipment that has broken down completely or is performing inefficiently. Addi-tional test instruments like different kinds of meters are necessary. 3

Radio and television service is primarily based on the proper use of tools and test instruments. It istherefore needed, that the technician knows the different sets of tools and test instruments and know how touse them. This lesson provides a comprehensive study of various testing instruments such as the ohmmeter,DC voltmeter,AC voltmeter, DC milliammeter and DC ammeter as well as the use of the different electronictools such as the soldering iron, desoldering tool, pincers, standard screwdriver, flat file, adjustable wrench,socket wrench, pliers, long nose pliers, side cutter and phillip’s screwdriver.Electronic Tools and their UsesLong nose pliers Side cutter PliersStandard Screwdriver Adjustable wrench Socket wrenchSoldering iron Desoldering tool 4

1. Soldering iron - solders different component leads on printed circuit board (PCB).2. Desoldering tool- desolders soldering leads from components3. Pincers - gets components mostly in a deeper location of electronic equipment.4. Standard screwdriver - tightens and loosens standard screws.5. Phillip’s screwdriver - tightens philip screw.6. Flat file - smoothens the rough edges of PCB and cleans the soldering tip.7. Adjustable wrench - loosens and tightens square and octagon nuts.8. Socket wrench - tightens or loosens the octagon screw.9. Long nose pliers - holds wire and component leads while soldering.10. Diagonal cutter - cuts excess leads of components and wires.11. Ohmmeter - measures resistance unit in ohms.12. DC voltmeter - measures DC voltages in volts.13. AC voltmeter - measures AC voltages in volts.Activity 1 Cite at least two electronic activities you know and enumerate the tools and test instruments used.Self-check:1. How does a soldering iron differ from a desoldering tool?2. List down at least three handtools which an electronic technician seldom uses.3. Diagonal cutters and component are used to cut ______.4. What is the difference between a Phillip’s screwdriver and a standard screwdriver?5. Where is the long nose pliers used? Lesson 2 Testing Different Electronic ComponentsMeasuring Resistance Using V.O.M. Procedures1. Set the range selector to R x 1.2. Connect the end of the negative and positive test probes.3. Adjust the zero ohm adjuster to zero for accurate measurements. 5

4. Start measuring resistance.5. Note: When change in range selector occurs, adjust the zero ohm adjuster to zero reading for accurate measurements.Ohmmeter Reading1. When the V.O.M. is set to its R x 1 position, read the scale directly.2. If the instrument is operated on its R x 10 range, multiply the scale reading by 10.3. Multiply the scale reading by 1,000 if the R x 1K range is used.4. If the V.O.M. is operated on its R x 10K range, multiply the scale reading by 10,000.VOM - Volt Ohm MilliammeterRange Selector1. R x 12. K x 103. R x 1004. R x 1K5. R x 10KExample: Read the pointer indicated by numbers in meter scale and multiply the reading by the setting of rangeselector. Example: 1. R x 1 = 160 x 1 = 160 Ω 2. R x 10 = 34 x 2 = 68 Ω 6

Ohmmeter The ohmmeter is used to measure resistance. Thetopmost scale of a multimeter is for ohmmeter readings. It isshown in the figure below. Other scales are not shown tofocus your attention only on the scale for reading resistance.Zero is located on the right side of the meter. Infinity is on theleft side. Two steps should be taken before making any resistance measurement. The first step is to select aproper range or multiplier in the function selector. The second step is to adjust the needle or pointer to zeroreading. This is done by sorting together test prods and turning slowly the Ohms adjustment knob until theneedle points to zero reading. Zero adjustment should be done on any multiplier range. This procedure ensuresaccuracy of measurement. Zero adjustment Sanwa YX-360 TR tester in our examples has been chosen on the basis of its popularity amongtechnicians. There are four multiplier ranges in this Sanwa model: x1, x10, 1Κ and x 10Κ. The figure belowshows these ranges. The lowest range is x1. This range is used for measuring low resistances not exceeding 500 ohms. Forresistance measurements of less than 1000 ohms x10 range is more accurate. If a higher multiplier range ofx1K or x10K is used for this kind of resistance measurements it would appear as zero resistance. Theopposite is true when very high resistances are being measured at low multiplier ranges of x1 and x10: it wouldseem to be open although it may not be the case. For resistance values not exceeding 100,000 ohmsmultipliers x 1K and x10K can be used either way. 7

In actual practice, the resistance of a good resistor measured by tester may not coincide with its resis-tance value indicated by the color on its body. This difference is due to what is called tolerance. A resistor isconsidered defective if the value of the resistor differs by more than 20% from its original color coded value.Reading Exercises FigureA Suppose we have a 100 ohms resistor which we would like to check. For this particular resistancerange x1 or x10 can be used. Figure Aand B show meter readings in both ranges. Figure B In FigureA, the needle points to 100 ohms. This is direct reading because 100 multiplied by 1 equals100. Figure B shows the needle pointed at number 10 which when multiplied by 10 also equals 100 ohms. After these two examples you will be able to take measurements of higher resistances yourself. All youhave to do is to multiply the reading on the scale by a multiplier to which the selector is set. Should you comeacross unknown values of resistors try different multiplier settings to determine actual resistance. More practiceeducates the user to decide quickly on the proper multiplier needed for a given value of a resistor. 8

Wrong Correct A meter is highly sensitive when used to measure very high resis-tances. Care should be taken not to hold the metallic part of the testprods of the tester. Holding these parts of test prods with your fingers orboth hands will render the test inaccurate and misleading because yourbody resistance will be parallel to the resistor or any other component youare testing. Figure C demonstrates human body resistance. Figure C When there is a need, a component under test may be held with one hand but make sure that the otherhand does not touch the metallic part of the test prods. It would be best to lay the component on the table sothat you could avoid holding it during the test. For low resistance test with 1x and x10 multipliers holdingcomponents with both hands is permitted because it will not affect measurements. The ohmmeter can be used only for resistance or continuity tests. Its accidental use for measuringcomponents under high voltage or electrical current will damage the meter. Before taking any resistance test ona radio under service make sure the power is off or unplug it. Another important thing to remember is to set thefunction selector to DC or AC when the ohmmeter is not used. This prolongs the life of the ohmmeter battery.In DC or AC functions, the battery is switched off. Prolonged shortening of tests prods when the meter is setto ohmmeter function will discharge the battery because it is in series with test prods. It is recommended thattest prods are removed from the meter when it is not in use or is stored for safe keeping.Measuring DC Voltage, AC Voltage and Current in DCProcedure:1. Set the range selector to the highest range if you are measuring “unknown” voltage. (1000V).2. If you are measuring DC voltages, set your range selector to DCV ranges.3. If you are measuring AC voltages, set your range selector to ACV ranges. 9

4. If you are measuring current, set your range selector to DCMA ranges. When your range selector is set at the following selector ranges, the multipliers are as follows:Range Selectors1000 V-multiply by 20 per line500 V -multiply by 10 per line250 V -multiply by 5 per line50 V -multiply by 1 per line25 V -multiply by .5 per line10 V -multiply by .2 per line5 V -multiply by .1 per line2.5 V -multiply by .05 per line1 V -multiply by .02 per line.5 V -multiply by .01 per line.1 V -multiply by .002 per lineExample: Pointer 1 Pointer 2 0 5 10 15 20 25 30 35 40 45 501. If your range selector is set to 500 V and your pointer deflects to 3rd line, 3 x 10 = 30 V.2. If your range selector is set to 250 V and your pointer deflects to 18th line, 18 x 5 = 90 V. The figure below shows three sets of scales used forAC and DC measurements. AC and DC voltageswill be discussed later in the text. In the meantime do not bother with the type of voltage you are going to test. 10

For voltage readings, zero is located on the left side of the voltmeter scale. The pointer of the meterrests on the left and moves towards the right. The voltage range selector indicates the maximum capacity of thevoltmeter to measure such voltages. For example, in measuring voltages which are expected to be less than 10volts the voltage selector can be set to range 10 V. The scale reading will be taken from 0-10 V scale. Similarly, if the expected voltage is less than 1000 volts the voltage selector should be set to 1000 V.The scale reading will be taken from 0-10 V scale. The next scale is 0-50. It is used for voltage reading of two different settings of the voltage selector onDC function. When the expected voltage is about 50 volts, the selector is set to 50 V range. The voltagereading in this case will be direct because the scale is equal to the voltage range setting. The figure belowdemonstrates the reading and the setting of the range selector. Another voltage range available on DC function is .5 volt. Reading is take from 0-50 V scale. Theneedle points at number 20 at scale. Thus the voltage reading is .2 volt. 11

The lowest voltage range of the meter is .1 volt. The reading is taken from 0-10 V scale. The needlepoints at number 6 which means a reading of .06 volt. The last scale we are going to deal with is 0-250V. There are two voltage selector settings that can beused for reading from this scale. If the expected voltage is less than 250 volts, the selector is set to 250 V andthe reading can be directly taken from the scale. The reading is 150 volts. The lower voltage setting is 2.5 volts. The same 0-250 V scale is used for voltage readings of thissetting. The figure below shows an example of this voltage reading. The pointer is at 100 while the setting is2.5 volts. The reading is 1 volt. 12