Basic Electronics

Technology and Livelihood Education

AREA:

BASIC ELECTRONICS

LET Competencies: 1. Apply the Fundamentals of Electronics in Household Appliances 2. Identify Electronic Tools and Components used in Common Household Appliances Appliances 3. Interpret Electronics Schematic Diagram 4. Analyze Basic Electronic Circuit Trouble in Appliances 5. Appraise the Result of Simple Electronic Circuit Repair

STUDYING

PART I: CONTENT UPDATE

FUNDAMENTALS OF ELECTRONIC

ELECTRONICS Electronics is the branch of science and engineering concerned with the theory, design, and the use of devices which involve the transmission of power by utilizing electron emission or absorption. Electronics includes all aspects of photoelectric cells, transistors, circuits, cathode-ray tubes, electron tubes, oscilloscopes, electron microscopes, broadcasting, radio, television, telephone, and many other industries. DEFINITION OF TERMS

1. Electronic components - is any physical entity in an electronic system whose intention is to affect the electrons or their associated fields in a desired manner consistent with the intended function of the electronic system 2. Electrical Circuit - is a network that has a closed loop, giving a return path for the current 3. Network - is a connection of two or more components, and may not necessarily be a circuit 4. Conductors – are metals and other substances where electrons can move freely 5. Insulators – substances where electrons cannot move freely 6. Transformer – is an electronic devised used in producing desired voltage 7. Inductors – the choke or coil in a circuit that oppose changes in electric current 8. Semiconductors – a group that are neither good conductors nor good insulators BASIC ELECTRONIC TOOLS 1. Electric Drill and Drill Bits - in the range of 1/8 inch to 1/2 inch will come in handy when you need to drill holes on the printed circuit board that has been etched. Drilling of plastic or metal enclosure that houses the printed circuit board are sometimes necessary. 2. Soldering Iron - a 20 Watt to 30 Watt soldering iron with tips of 1/8 inch to 1/2 inch can be used for soldering of through hole components. Soldering of surface mount components may require smaller tips depending on the sizes of the components. Soldering iron normally will last a long time if it is taken care of properly by keeping the tips clean and well tinned.

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3. Disordering Pump - A pump aids in the removal of the liquid solder. It is operated by a spring-loaded vacuum pump and controlled by a simple trigger. 4. Vacuum Pick Up Tool - A pick and place head for transferring die or chips containing electronic circuitry from waffle packs to substrates prior to lead bonding operations. 5. Soldering Stand - It keeps the iron away from flammable materials 6. Helping Hand Tool - A crucial tool in doing successful electronics work. It consists of a weighted base, arms ending in alligator clips, magnifying glass and flexible joint. 7. Wire strpper - is used to strip off wire insulator from its conductor before it is used to connect to another wire or soldered into the printed circuit board. Some wire stripper or wire cutter has a measurement engraved on it to indicate the length that will be stripped. 8. Long nose Pliers – a 4-inch long nose pliers will come in handy when you need to hold components that have short leads that need to be soldered onto the PCB but will be too hot to handle with bare hands. It will also be useful to hold the component that needs to be de-soldered from the board. 9. Side-Cutting Pliers - 4-inch side cutting pliers will come in handy as one of the electronic tools when one need to trim off excess component leads on the printed circuit board. It can also be used to cut wires into shorter length before being used. 10. Small tweezers - is used to hold small components especially when doing soldering and de-soldering of surface mount components. 11. Allen Wrench set - set is sometimes used to unscrew or screw Allen type of screws. 12. Philips Head Screwdrivers -various sizes of Philips head screwdrivers will be handy as a lot of electronics projects that use screws are Philips Head type. 13. Flat Head Screwdrivers - of various sizes are also necessary as many screws that are used are of this type. 14. Hammer - a small, light hammer will be useful when assembling projects that involved casing. 15. Socket wrench - sets that include nut drivers, hex drivers, and starters in assorted sizes will come in handy during the assembly work of electronics project. 16. Pocket Knife - will be useful when one need to cut PCB, wires or remove some cooper from the printed circuit board. Maintenance Tips of Electronic Tools Good quality tools that are being purchased can last a lifetime if they are taken care of properly. 1. Ensure that the tools are used only for their intended purposes. 2. Keep them lubricated with a light film of oil to inhibit rust. 3. Keep the tools clean and sharp; keep the soldering tips clean and well well tinned. 4. Ensure that proper uses of of the tools are always adhered to by following the instructions of using the tools. ELECTRONIC COMPONENTS These are the basic electronic element usually packaged in a discrete form with two or more connecting leads or metallic pads in which intended to be connected together, usually by soldering to a printed circuit board, board, to create an electronic circuit with a particular function (for example an amplifier, radio receiver, or oscillator) oscillator) may be packaged singly (resistor, capacitor, transistor,

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diode etc.) or in more or less complex groups as integrated circuits (operational amplifier, resistor array, logic gate etc.)

CAPACITORS Capacitor is a device able to temporarily store electricity. It was invented by Ewald Georg von Kleist (October 1745). These relatively simple components consist of two pieces of conducting material (such as metal) separated by a nonconducting (insulating) material called a dielectric. When a voltage potential difference exists between the conductors, an electric field is present in the dielectric. This field stores energy and produces a mechanical force between the plates. The effect is greatest between wide, flat, parallel, narrowly separated conductors. Types of Capacitor 1. Electrolytic Capacitor (Electrochemical Type Capacitor) 2. Tantalum Capacitor 3. Ceramic Capacitor 4. Polystyrene Film Capacitor 5. Mica Capacitor 6. Metallized Polyester Capacitor 7. Variable Capacitor 8. Trimmer Capacitor DIODE This device is used to limit the movement of electricity to move in one specific direction. Some diodes are also designed to produce light or to act as a switch in an electrical circuit. It has two active electrodes between which the signal of interest may flow, and most are used for their unidirectional electric current property. Diode also allows an electric current to flow through them in only one direction. They are also known as rectifiers. It can be used to change alternating currents (ones flowing back and forth round a circuit, constantly swapping direction) into direct currents (ones that always flow in the same direction). Types of Diode 1. Light Emitting Diode (LED) 2. Avalanche Diode 3. Laser Diode 4. Schottky Diodes 5. Zener diode 6. Photodiode 7. Varicap Diode or Varactor Diode Rectifier Diode TRANSISTOR An electrical circuit needs to have switches to control the current. In electronic equipment, the most useful kind of switch is the transistor. Transistors is invented by William Shockley which considered by many as the father of transistor. This device commonly varies in composition and in the arrangement of the components. It is use to amplify or switch electronics signals which is made of a solid piece of a semiconductor material, with at least three terminals for connection to an external circuit. The diagram below shows the components in one kind of transistor.

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Gate: The post of a transistor that receives the current used to turn the switch on completing the circuit so electricity can flow Source: The post of a transistor where the current in the closed circuit enters the transistor Drain: The post of a transistor that passes the current from the transistor and on through the closed circuits

A transistor is turned on when an electrical charge is applied to the gate. This changes the electrical charge in the transistor to allow electrons to move from the source to the drain. If the transistor is turned off —no electrical charge on the gate —the pathway of the circuit is broken and the current stops. RESISTOR This device is the simplest components in any circuit. With a measurable ability to resist the flow of electrons used to control the strength of the current in a circuit. Resistors come in many different shapes and sizes. Variable resistors (also known as potentiometers) have a dial control on them so they change the amount of resistance when you turn them.

Europe Resistor Symbol

United State Resistor Symbol

Type of Resistor 1. Variable Resistor (Potentiometer) 2. Variable Resistor (Preset) 3. Carbon Composition Resistor 4. Film or Cermet Resistor 5. Wire-Wound Resistors 6. Metal oxide film resistors 7. Vitreous Enamel Resistors 8. Cement resistors 9. Semiconductor Resistors RESISTOR COLOR CODING COLOR

1ST band

2nd band

Black Brown Red Orange

0 1 2 3

0 1 2 3

r

3 band (multiplier)

4 band (tolerance)

+ 1% (F) + 2% (G)

Temp. Coefficient

100 ppm 50 ppm 15 ppm

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Yellow Green Blue Violet Gray White Gold Silver None

4 5 6 7 8 9

4 5 6 7 8 9

25 ppm + 0.5 % (D) + 0.25% (C) + 0.1% (B) + 0.05% (A) + 5% (J) + 10% (K) + 20% (M)

Example

TYPES OF CIRCUIT BOARD 1. Breadboard - Temporary, no soldering required - This is a way of making a temporary circuit, for testing purposes or to try out an idea. - No soldering is required and all the components can be re-used afterwards. - It is easy to change connections and replace components 2. Strip board - Permanent, soldered - Strip board has parallel strips of copper track on one side. The strips are 0.1" (2.54mm) apart and there are holes every 0.1" (2.54mm). - Strip board requires no special preparation other than cutting to size. It can be cut with a junior hacksaw, or simply snap it along the lines of holes by putting it over the edge of a bench or table and pushing hard. 3. Printed Circuit Board

-

Permanent, soldered Printed circuit boards have copper tracks connecting the holes where the components are placed.

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ELECTRONIC SCHEMATIC DIAGRAM Simple Amplifier Circuit Diagram

ELECTRONIC SYMBOLS 1. Resistor Component Circuit Symbol

Resistor

Variable Resistor (Rheostat)

Variable Resistor (Potentiometer)

Variable Resistor (Preset)

2. Capacitors Component

Capacitor

Circuit Symbol

Physical circuit

Function of Component A resistor restricts the flow of current, for example to limit the current passing through an LED. A resistor is used with a capacitor in a timing circuit. This type of variable resistor with 2 contacts (a rheostat) is usually used to control current. Examples include: adjusting lamp brightness, adjusting motor speed, and adjusting the rate of flow of charge into a capacitor in a timing circuit. This type of variable resistor with 3 contacts (a potentiometer) is usually used to control voltage. It can be used like this as a transducer converting position (angle of the control spindle) to an electrical signal. This type of variable resistor (a preset) is operated with a small screwdriver or similar tool. It is designed to be set when the circuit is made and then left without further adjustment. Presets are cheaper than normal variable resistors so they are often used in projects to reduce the cost.

Function of Component A capacitor stores electric charge. A capacitor is used with a resistor in a timing circuit. It can also be used as a filter, to block DC signals but pass AC signals.

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Capacitor, polarized

A capacitor stores electric charge. This type must be connected the correct way round. A capacitor is used with a resistor in a timing circuit. It can also be used as a filter, to block DC signals but pass AC signals.

Variable Capacitor

A variable capacitor is used in a radio tuner.

Trimmer Capacitor

This type of variable capacitor (a trimmer) is operated with a small screwdriver or similar tool. It is designed to be set when the circuit is made and then left without further adjustment.

3. Diodes Component

Circuit Symbol

Diode

Function of Component A device which only allows current to flow in one direction.

LED Light Emitting Diode

A transducer which converts electrical energy to light.

Zener Diode

A special diode which is used to maintain a fixed voltage across its terminals.

Photodiode

A light-sensitive diode.

4. Transistor Component

Circuit Symbol

Function of Component

Transistor NPN

A transistor amplifies current. It can be used with other components to make an amplifier or switching circuit.

Transistor PNP

A transistor amplifies current. It can be used with other components to make an amplifier or switching circuit.

Phototransistor

A light-sensitive transistor.

5. Audio and Radio Devices Component Circuit Symbol

Function of Component

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Microphone

A transducer which converts sound to electrical energy.

Earphone

A transducer which converts electrical energy to sound.

Loudspeaker


Piezo Transducer


Amplifier (general symbol)

Aerial (Antenna)

6. Meters and Oscilloscope Component Circuit Symbol

Voltmeter

Ammeter

Galvanometer

Ohmmeter

Oscilloscope

7. Sensors (input devices) Component Circuit Symbol

An amplifier circuit with one input. Really it is a block diagram symbol because it represents a circuit rather than just one component. A device which is designed to receive or transmit radio signals. It is also known as an antenna.

Function of Component A voltmeter is used to measure voltage. The proper name for voltage is 'potential difference', but most people prefer to say voltage.

An ammeter is used to measure current. A galvanometer is a very sensitive meter which is used to measure tiny currents, usually 1mA or less. An ohmmeter is used to measure resistance. Most multimeters have an ohmmeter setting. An oscilloscope is used to display the shape of electrical signals and it can be used to measure their voltage and time period. Function of Component

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A transducer which converts brightness (light) to resistance (an electrical property). LDR = Light Dependent Resistor A transducer which converts temperature (heat) to resistance (an electrical property).

LDR

Thermistor

8. Logic Gates Gate Traditional Type Symbol

NOT

AND

NAND

OR

NOR

EX-OR

EXNOR

IEC Symbol

Function of Gate

A NOT gate can only have one input. The 'o' on the output means 'not'. The output of a NOT gate is the inverse (opposite) of its input, so the output is true when the input is false. A NOT gate is also called an inverter. An AND gate can have two or more inputs. The output of an AND gate is true when all its inputs are true. A NAND gate can have two or more inputs. The 'o' on the output means 'not' showing that it is a Not AND gate. The output of a NAND gate is true unless all its inputs are true. An OR gate can have two or more inputs. The output of an OR gate is true when at least one of its inputs is true. A NOR gate can have two or more inputs. The 'o' on the output means 'not' showing that it is a Not OR gate. The output of a NOR gate is true when none of its inputs are true. An EX-OR gate can only have two inputs. The output of an EX-OR gate is true when its inputs are different (one true, one false). An EX-NOR gate can only have two inputs. The 'o' on the output means 'not' showing that it is a Not EXOR gate. The output of an

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EX-NOR gate is true when its inputs are the same (both true or both false).

BASIC ELECTRONIC CIRCUIT TROUBLE IN APPLIANCES

1. Broken wiring inside cord set - internal breaks in the conductors of cord sets or other connecting cords caused by flexing, pulling, or other long term abuse. This is one of the most common problems with vacuum cleaners which tend to be dragged around by their tails. 2. Bad internal connections - broken wires, corroded or loosened terminals. Wires may break from vibration, corrosion, poor manufacturing, as well as thermal fatigue. The break may be in a heating element or other subassembly. In many cases, failure will be total as in when one of the AC line connections falls off. At other times, operation will be intermittent or erratic - or parts of the appliance will not function. For example, with a blow dryer, the heating element could open up but the fan may continue to run properly. 3. Short circuits – When two wires touching or contacting the metal case of an appliance happens too often. Partially, this is due to the shoddy manufacturing quality of many small appliances like toaster ovens. These also have metal (mostly) cabinets and many metal interior parts with sharp edges which can readily eat through wire insulation due to repeated vibrations, heating and cooling cycles, and the like. A short circuit may develop with no operational problems - but the case of the appliance will be electrically 'hot'. This is a dangerous situation. Large appliances with 3 wire plugs - plugged into a properly grounded 3 wire circuit would then blow a fuse or trip a circuit breaker. However, small appliances like toaster, broilers, irons, etc., have two wire plugs and will just set there with a live cabinet. 4. Worn, dirty, or broken switches or thermostat contacts - These will result in erratic or no action when the switch is flipped or thermostat knob is turned. In many cases, the part will feel bad - it won't have that 'click' it had when new or may be hard to turn or flip. Often, however, operation will just be erratic jiggling the switch or knob will make the motor or light go on or off, for example. 5. Gummed up lubrication, or worn or dry bearings - Often, due to environmental conditions (dust, dirt, humidity) or just poor quality control during manufacture, a motor or fan bearing will gum up or become dry resulting in sluggish and/or noisy operation and overheating. In extreme cases, the bearing may seize resulting in a totally stopped motor. If not detected, this may result in a blown fuse (at the least) and possibly a burnt out motor from the overheating. 6. Broken or worn drive belts or gears - rotating parts do not rotate or turn slowly or with little power even through the motor is revving its little head off. When the brush drive belt in an upright vacuum cleaner breaks, the results are obvious and the broken belt often falls to the ground (to be eaten by the

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dog or mistaken for a mouse tail. However, there are often other belts inside appliances which will result in less obvious consequences when they loosen with age or fail completely. 7. Broken parts - plastic or metal castings, linkages, washers, and other 'doodads' are often not constructed quite the way they used to be. When any of these fail, they can bring a complicated appliance to its knees. Failure may be caused by normal wear and tear, improper use, accidents, or shoddy manufacturing. 8. Insect damage - Many appliances make inviting homes for all sorts of multilegged creatures. Evidence of their visits or extended stays will be obvious including frayed insulation, short circuits caused by bodily fluids or entire bodies, remains of food and droppings. Even the smallest ventilation hole can be a front door. SIMPLE ELECTRONIC CIRCUIT REPAIR

1. Broken wiring inside cord set If the problem is intermittent, plug the appliance in and turn it on. Then try bending or pushing the wire toward the plug or appliance connector end to see if you can make the internal conductors touch at least momentarily. If the cord set is removable, test between ends with a continuity checker or multimeter on the low ohms scale. If it is not detachable, open the appliance to perform this test. 2. Bad internal connections In many cases, a visual inspection with some careful flexing and prodding will reveal the location of the bad connection. If it is an intermittent, this may need to be done with a well insulated stick while the appliance is on and running. When all else fails, the use of a continuity checker or multimeter on the low ohms scale can identify broken connections which are not obviously wires visibly broken in two. For testing heating elements, use the multimeter as a continuity checker may not be sensitive enough since the element normally has some resistance. 3. Short circuits Visually inspect for bare wires or wires with frayed or worn insulation touching metal parts, terminals they should not be connected to, or other wires. Use a multimeter on the high ohms scale to check between both prongs of the AC plug and any exposed metal parts. Try all positions of any power or selector switches. Any resistance measurement less than 100K ohms or so is cause for concern - and further checking. Also test between internal terminals and wires that should not be connected together. 4. Worn, dirty, or broken switches or thermostat contacts Where there is a changed feel to the switch or thermostat with an associated operational problem, there is little doubt that the part is bad and must be replaced. Where this is not the case, label the connections to the switch or thermostat and then remove the wires. Use the continuity checker or ohmmeter across each set of contacts. They should be 0 ohms or open depending on the position of the switch or knob and nothing in between. In most cases, you should be able to obtain both readings. The exception is with respect to thermostats where room temperature is off one end of their range. Inability to make the

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contacts open or close or erratic intermediate resistances which are affected by tapping or jiggling are a sure sign of a bad set of contacts. 5. Gummed up lubrication, or worn or dry bearings If the appliance does not run but there is a hum (AC line operated appliances) or runs sluggishly or with less power than you recall when new, lubrication problems are likely. With the appliance unplugged, check for free rotation of the motor(s). In general, the shaft sticking out of the motor itself should turn freely with very little resistance. If it is difficult to turn, the motor bearings themselves may need attention or the mechanism attached to the motor may be filled with crud. In most cases, a thorough cleaning to remove all the old dried up and contaminated oil or grease followed by relubing with similar oil or grease as appropriate will return the appliance to good health. Don't skimp on the disassembly - total cleaning will be best. Even the motor should be carefully removed and broken down to its component parts - end plates, rotor, and stator, brushes (if any) in order to properly clean and lubricate its bearings. 6. Broken or worn drive belts or gears Except for the case of a vacuum cleaner where the belt is readily accessible, open the appliance. A good rubber belt will be perfectly elastic and will return to its relaxed length instantly when stretched by 25 percent and let go. It will not be cracked, shiny, hard, or brittle. A V-type belt should be dry (no oil coating), undamaged (not cracked, brittle, or frayed), and tight (it should deflect 1/4" to 1/2" when pressed firmly halfway between the pulleys). 7. Broken parts In many cases, the problem will be obvious. Where it is not, some careful detective work - putting the various mechanisms through their paces - should reveal what is not functioning. Although replacement parts may be available, you can be sure that their cost will be excessive and improvisation may ultimately be the best approach to repair.

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PART II: ANALYZING TEST ITEMS Competency No. 1 Apply the Fundamentals of Electronics in Household Appliances

1. What branch of physics refers to the flow of electron through nonmetal conductors? A. Mechanics C. Electricity B. Physics D. Electronics The correct answer is D. Electronics Option A deals with energy and forces and their effects on the bodies Option B refers to experimental science Option C refers to the basic forms of energy

Competency No. 2 Identify Electronic Tools and Components used in Common Household Appliances

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2. It is an electronic tool that is use to strip off wire insulator from its conductor. A. wire stripper C. small tweezers B. socket wrench D. long nose pliers The correct answer is A. wire stripper Option B used for gripping Option C is small tweezers it is used to hold small components Option D is long nose pliers it is used to hold components that have short leads Competency No. 3 Interpret Electronics Schematic Diagram 3. LDR refers to? A. Light Dependent Resistor B. Light Devices Resistor

C. Light Diode Resistant D. Light Depending Resistor

The correct answer is A. Light Dependent Resistor Option B does not apply to the question Option C does not apply to the question Option D does not apply to the question Competency No. 4 Analyze Basic Electronic Circuit Trouble in Appliances 4. Circuit troubles such as broken wires, corroded or loosened terminals show: A. short circuits C. broken wiring B. broken parts D. bad internal connections The correct answer is D. bad internal connections Option A is circuit trouble that caused contraction of metal case Option B is circuit trouble that caused linkages and complication to appliances Option C is circuit trouble that caused internal breaks in the conductors

Competency No. 5 Appraise the Result of Simple Electronic Circuit Repair

5. What should be the repair in a broken wiring? A. bends or pushes the wire toward the plug or appliance connector end B. label the connections to the switch or thermostat C. inspect for bare wires or wires with frayed or worn insulation D. use the continuity checker or ohmmeter across each set of contacts The correct answer is A. Bend or pushes the wire toward the plug or appliance connector end Option B is used as a repair for worn or broken switches Option C is used as repair in short circuits Option D is used as a repair for broken circuit 6. The symbol for earphone

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a.

c.

b.

d.

7. Which voltage source converts chemical energy to electrical energy? a. Electrical generator c. Battery b. Solar cell d. Electronic power supply 8. What is the color code in 5 band for a 150 M + 10% resistor? a. Brown, Green, Black, Blue, and Gold b. Brown, Green, Black, Yellow, and Gold c. Brown, Green, Black, Blue, and Silver d. Brown, Green, Black, Yellow, and Silver 9. Which electronics material opposes the movement of free electrons? a. Element c. Conductor b. Insulator d. Semiconductor 10. The logic gate that will have HIGH or "1" at its output when any one of its inputs is HIGH is a(n): a. OR Gate c. Nor Gate b. Ex-Or Gate d. Ex-Nor Gate 11. Which among the types of circuit board can easily change the connections of components? a. Strip board c. Breadboard b. Printed circuit board d. None of the above 12. Which is the symbol for amplifier? a.

c.

b.

d.

13. What is the common characteristic of strip board and printed circuit board? a. temporary circuit board c. no soldering required b. permanent circuit board d. requires no special preparation 14. Which of the following is not an electronics component? a. diode c. resistors b. capacitors d. power 15. What does LED refers to? a. Light Emitting Diode b. Light Emission Devices

c. Light Emitting Devices d. Light Emission Diode

16. Which is NOT true about proper maintenance of electronic tools? a. Ensure that the tools are used only for their intended purposes.

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b. Keep the tools lubricated with soap and water inhibits rust. c. Keep the tools clean and sharp. d. Keeps the soldering tips clean and well tinned. 17. The symbol for transistor PNP a.

c.

b.

d.

18. If a signal passing through a gate is inhibited by sending a low into one of the inputs, and the output is HIGH, the gate is a(n): a. OR Gate c. AND Gate b. NOR Gate d. NAND Gate 19. One of the most common problems with vacuum cleaners is broken wiring inside cord set. This is due to _____________. a. flexing, wiring, long term abuse c. poor manufacturing b. vibration, corrosion d. dust, dirt, humidity 20. This symbol is used to measure voltage. a.

c.

b.

d.

21. A device which is designed to receive or transmit radio signals. a. Amplifier c. Antenna b. Ammeter d. Piezo Transducer 22. What electronic component is commonly used to amplify or switch electronic signals? a. capacitor c. diode b. transistor d. resistor 23. Use to assemble electronics appliances and project. a. electronics tools c. electronics components b. electronics unit d. electrical network

24. When using soldering iron in soldering surface mount component it requires ___. a. bigger tips c. narrow tips b. smaller tips d. wider tips 25. What is the color code in 5 band for a 63 M and 10% resistor? a. Blue, Orange, Black, Green and Gold b. Blue, Orange, Black, Green and Silver c. Blue, Yellow, Black, Green and Silver d. Blue, Red, Black, Green and Silver

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PART III: ENHANCING TEST TAKING SKILLS 1. What input values will cause an AND logic gate to produce a HIGH output? a. At least one input is LOW. b. At least one input is HIGH. c. All inputs are LOW. d. All inputs are HIGH. 2. Ohm's law describes the mathematical relationship between a. resistance, voltage, and current b. resistor size and resistor value c. ohms, kilohms, and megohms d. none of the above 3. One of the most common applications of a potentiometer is as an adjustable voltage divider, also known as a. divider control c. voltage control b. volume control d. current control 4. What is this symbol a. capacitor b. variable capacitor

? c. polarized capacitor d. timmer capacitor

5. What is the color code for a 220 5% resistor? a. Red, Red, Brown, Silver b. Red, Red, Brown, Gold c. Red, Red, Black, Gold d. Orange, Orange, Black, Gold 6. Component that store electrical charge in an electrical field. a. capacitors c. resistors b. diode d. transistor 7. What electronic circuit trouble is affected of environmental condition such as dust, dirt, and humidity? a. broken wiring inside cord set c. short circuits b. gummed up lubrication d. insect damage 8. It is used to connect the holes where components are placed in a printed circuit board. a. terminal strip c. phenolic board b. copper tracks d. copper board 9. A NAND gate has:

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a. LOW inputs and a HIGH output output b. LOW inputs and a LOW output

c. HIGH inputs and a HIGH d. None of these above

10. This symbol is used to measure current. a. c. b. d. 11. What is the resistor value of Blue, Black, Silver? a. 60 K + 5% c. 60 K + 10% b. 50 K + 5% d. 50 K + 5%

Orange and

12. Electronic tools can last lifetime if they are ___________________. a. used in many purposes b. inhibit rust because they are not lubricated c. properly use based from the instructions given d. clean once in a while 13. A _____ is a device that resists the flow of charge. a. Resistor c. Diode b. Buffer d. Microfarad (or µF;) 14. In logic gate, the output will be a LOW for any case when one or more inputs are zero in a(n): a. OR Gate b. AND Gate c. NAND Gate d. NOT Gate 15. It is used to display the shape of electrical signals and it can be used to measure their voltage and time period. a. Galvanometer b. Ohmmeter c. Voltmeter d. Oscilloscope 16. What do you call a diagram that shows the electrical connections of a circuit's components? a. Schematic Diagram b. Block Diagram c. Pictorial Diagram d. Electronic Diagram 17. Which of these is the function of zener diode? a. allows current to flow in one direction b. converts electrical energy to light c. maintain a fixed voltage across its terminals d. produced a light-sensitive diode 18. A device designed to receive or transmit radio signals. a. loudspeaker c. microphone b. antenna d. amplifier

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19. What kind of network does electric circuit has? a. opened loop c. closed loop b. one loop d. two loop 20. In logic gates, the output is true when its inputs are different. a. OR Gate c. EX-OR Gate b. NOR Gate d. EX-NOR Gate 21. A kind of diode which converts electrical energy to light. a. Rectifier diode c. Varicap Diode b. Zener Diode d. Light Emitting Diode 22. A very sensitive meter which is used to measure tiny currents a. Galvanometer c. Ohmmeter b. Ammeter d. Volt Meter 23. It is used to limit the movement of electricity to move in one specific direction. a. Capacitor c. Transistor b. Resistor d. Diode 24. Which type of logic gate has one input? a. NOT Gate c. AND Gate b. NAND Gate d. NOR Gate 25. A standard wattage for soldering iron is a. 20W to 10W c. 20W to 40W b. 20W to 30 W d. 20W to 50W

ANALYZING TEST ITEMS

1. D 2. A 3. A 4. D 5. A 6. B 7. C 8. A 9. D 10. A 11. C

ANSWER ENHANCING TEST TAKING SKILLS

1. D 2. A 3. B 4. C 5. B 6. A 7. B 8. B 9. A 10. B 11. C

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12. C 13. B 14. B 15. A 16. B 17. B 18. D 19. A 20. D 21. C 22. C 23. A 24. B 25. B

12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25.

C A B D A C B C C D A D A B

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Basic Electronics

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