Basic Electronic In Laptop Repairing.pdf

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Contents : Static electricity and its history Coulomb's law Categorizing objects Current electricity Electric current intensity The concept of electrical resistance The concept of voltage Ohm law The concept of electric power Things related to power Resistor and its types Detecting resistance amount from color bands Reading resistance from numeric codes and Latin letters The concept of tolerance (error percentage) of resistors Resistors’ standard amounts The final problems of the chapter

Electricity and electronic principle Static electricity and its history The origin of human knowledge of electricity can be estimated to be from 600 BC, when Greek philosopher Thales discovered that, amber can attract light objects by rubbing. And the name electricity comes from “electron”, the Greek word for amber.

Attracting light objects with amber

Creating static electricity in objects by rubbing was experienced until the end of 18 century by many scientists including “Otto von Guericke”. In those experiments, they realized that: some of the objects have the Property of attracting or repelling other objects by rubbing. In other words, they can apply force to each other. Existence of the force is because of the existence of «Electrical load» in objects. That’s why it’s called «Electric force».

Coulomb's law: The reason of force existence between 2 loaded objects can be justified like this: there is an »Electric field «around each loaded object and even though it can’t be seen by the eyes, it’s real. For the first time a French physicist, “Coulomb” could experimentally measure the force between loaded objects in 1785. He also got a relation for the force amount which is:

Force between 2 loaded particles depends on load amount of each one, distance between 2 loads and also environment material that the 2 loaded particle are in. Electrical load unit is called Coulomb and it is equivalent to electrical load of 6.24 * 1018 electron.

-1.6*10-19 An electron is approximately equals to Coulomb. The negative sign next to the number (-1.6) doesn't have any effect on its amount and it’s only to show the negative load of electron.

Categorizing objects: Objects in nature are electrically divided into three categories: A: Insulator or non-conductor: The objects in which there are no free electrons. Glass, Mica, Rubber and Wood are among them. Electricity in those objects are static and they stay (static) at one point.

Glass

Mica

B: Conductor: The objects that have a large number of free electrons, such as copper, silver and aluminum. The generated electricity is uniformly distributed over the metal surface due to the ability of the electrical load to move in the metal.

Aluminum bars

Copper cables

C: Semiconductor: The objects that are electrically between conductors and insulators. In other words, they are the elements that have 4 electrons in their outer shell of atom. Like silicon and germanium:

Molecular structure of silicon

Germanium Transistor

Current electricity: In 1799, Italian physicist Alessandro Volta was able to generate electricity by his own voltaic pile and send a continuous current in the wires. He called this electricity "current electricity".

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Electric current intensity: The amount of electrical load changes in time unit is called electric current.

If the movement of electrons is uniformly in a steady direction in the wire, the current is called D.C and its amount is calculated with the formula below :

t: Time in terms of second q: Amount of electrical load in terms of Coulomb I: Electric current in terms of Ampere The number of electrons that pass from a point of circuit determines the amount of current flow from the circuit. The higher the number of the electrons, the more the “current flow”.

Amperage definition: An ampere is electric current of wire and one Coulomb electrical load (6.24*1018 electron) flows from its specific section surface in one second. Electric current is represented by the Latin letter I (the first letter of Intensity) and its unit is indicated by A ampere. The smaller amperage units are: One thousandth of ampere=1mA and One millionth of amp=1μA. m= milli μ=micro

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Resistance The concept of Electrical resistance The electrical resistance is a factor that prevents the flow of electric current. The resistor is represented by the Latin letter R (the first letter of Resistance) and its unit is in terms of ohm with the Latin letter Ω. Larger ohm units: One thousand ohm= one Kilo Ohm= 1KΩ One million ohm= one Mega Ohm= 1MΩ

Voltage The concept of voltage The potential difference between two points of circuit is the amount of energy that electrical load consumes to move from one point to another.

v: Voltage in terms of volt w: Energy in terms of Joule q: Electrical load in terms of Coulomb Definition of Volt: one volt is the potential difference of two points of circuit. When one Coulomb electrical load (6.24*1018 electron) consumes one joule energy while moving from those two points, it would be one volt. Voltage is represented by Latin letter V (first letter of voltage) and its unit is indicated in terms of V volt. Ohm’s Law

when current intensity I flows from resistor R, the potential difference V will be created in both sides of the resistor and the amount is obtained by the following formula :

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This law is named after its discoverer Georg Ohm.

Ohm triangle:

The resulting relationships of Ohm's law:

Concept of electric power The work which is done in a time unit is called electric power which is obtained from the following relation:

P: Electric power in terms of watt w: Energy in terms of Joule t: Time in terms of second Electric power is represented by Latin letter P (first letter of Power) and its unit is indicated in terms of W watt. Allowed power, is the maximum power that a device can tolerate. The resulting relationships of power formula:

As a result, the final formula of power is as follows: Problem 1: What is resistance of a 100 watt light bulb ?

Problem 2: What happens if we connect a 100 watt with 110 volt light bulb to a 220 volt power ?

P1=100w V1=110v V2=220V First solution: First, we calculate the resistance of the light bulb:

The bulb burns due to quadrupled (4 times of) power Second solution: We calculate the allowed current of the bulb:

Bulb burns because current is doubled. Result: resistors burn, in case power and current intensity raise from the allowed limit Problem 3: Calculate the resistance of a 1000 watt electric heater compared to a 200 watt bulb.

V=220v P1=1000w P2=200w

Bulb resistance is 5 times of heater resistance. Result: The higher the power of the consumer devices, the lower their resistance. Problem 4: how much ampere does a 3300 watt air conditioner use? P=3300w V=220v I=?

Air conditioner uses 15 ampere (the current)

Resistor

Types of resistors in terms of placement on PCB circuits: A) SMD or SMT Surface Mount Device (SMD) Surface Mount Technology (SMT)

They are placed on the surface.

B) PTH Plated Through Hole (PTH)

Placing pin through a hole.

B: types of resistors in terms of usage on circuits 1. 2. 3. 4. 5.

Fixed resistors Adjustable Resistors Variable Resistors Array Resistors Printed Carbon Resistors

1- Fixed Resistors: These resistors are divided into 2 types in terms of production (1- Wire wound 2Composition) A) Wire Wound Resistor Types of wire wound resistors divide into Cement-Clay-Chinese resistors depending on their insulation. There is coil inside them. Wires are usually made of alloys (nickel-copper) / (nickel-chromium) / (nickel-chromium-aluminum) Wire wound resistors have lower ohm and higher power compared to composition ones and their size (Wire wound resistors) is also bigger.

B) Composition Composition Resistors include 1234-

Carbon composition Resistors Carbon film Resistor Metal film Resistor Metal oxide film Resistor

Carbon composition Resistors: carbonic compositions (mixture of carbon powder) is formed (formwork) as dough with resin and resistant materials, and cooked in a furnace and covered with insulator. These resistors are small in size with high resistance but low tolerance, from one fourth watts to two watts.

Carbon film Resistor: This type of resistor is made of sedimentation of a thin layer of carbon on a ceramic bar, and groves will be created on the resistor for increasing its amount, then the set is covered with insulator.

Metal film Resistor: This type of resistor is made on glass material bar and a thin layer of gold, platinum and silver (metals) is covered on it and then grooves will be created on the layer. The disadvantages of these resistors are expensiveness and power limitation (1 watt).

Metal oxide film resistor: This type of resistor is somehow like the metal film resistor with a difference that, tin and antimony metal oxides are used instead of metal cover.

Adjustable resistors: (knobs) These resistors are used in radio, Television and audio devices as adjustable resistors (manually) in order to turn up and down volume or adjust brightness which are usually carbonic and wire types are used in high power. Types of these resistors are : Potentiometer: A potentiometer is used to change the voltage

Rheostat: it is used to change the resistance

Trimmer: Instead of a moving handle, it has a groove which should be adjusted with a screwdriver.

The way these resistors work is that they have two fixed and one variable pins. The resistance amount between the two fixed pins (2 side pins), which in fact determines the potentiometer’s amount, is a fixed amount. While the resistance between the pin in the middle and either of the side pins can be changed by a revolving axis (knob handle).

Variable Resistors (Varistor)

These types of resistors change without mechanical actions and they change under factors such as voltage, heat, light and magnetism, and are divided on the same basis.

Symbolic circuit of Varistor

A) Voltage Dependent Resistor (VDR) This type of resistor’s resistance changes depending on the amount of applied voltage and it is used to keep the voltage fixed in a point of circuit and its resistance decreases when voltage increases.

B) Thermal Resistor (Thermistor) It is divided into two categories:

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Positive Temperature Coefficient (PTC) A thermistor with positive thermal coefficient’s resistance amount increases when heat increases.

The impedance written on these resistors is measured at 25 degrees Celsius. Negative Temperature Coefficient (NTC) A thermistor with negative thermal coefficient’s resistance amount decreases when heat increases and is made of various oxides Fe2O3, MnO2, NiO. To neutralize undesirable changes of the currents and voltages of the elements by heat, it is used as thermostat to prevent the temperature from rising and to prevent the very high instantaneous current intensity.

C: Light Dependent Resistor (LDR) Resistance amount decreases due to the intensity of light. And its main material is cadmium sulfide.

D: Magnetic Dependent Resistor (MDR) The resistance amount of these resistors changes by applying the magnetic field, in a way that by increasing the field, their ohm amount decreases.

E: There are other variable resistors which their resistance amount changes by humidity, gas

Array or Network resistors The array resistor actually contains a set of several resistors inside a package, which are available both in SMD and PTH, and the internal resistance amounts are all equal. In logic circuits, they are being used to pull up and pull down the inputs and outputs, they are also used in LED circuits. In SMD type, pins across from each other make separated resistors and they don’t have common pin.

In the PTH type, a pin (which is marked) is the common pin, and each of the other pins make a resistor with the common pin.

Printed carbon resistors These resistors are carbon mix type and are printed directly on fiber layers of PCB circuit. This type of resistor’s tolerance (error percentage) is high (even up to 30%) and it can’t be replaced.

Detecting resistance amount from color bands 1- Four colors:

First and second bands = Numbers Third band = coefficient or number of zeros Fourth band = Tolerance or error percentage The order of reading resistance amount

Tolerance+-(Coefficient*Numbers)

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2- Five colors:

First, second and third bands= Numbers Fourth band = coefficient or number of zeros Fifth band = Tolerance (Error Percentage) The order of reading resistance amount:

Tolerance+-(Coefficient*Numbers)

3- Body, end and point color: This type is the British standard (B.S) which was used in older devices

Body and end colors= numbers Dot color= coefficient or number of zeros Initial (beginning) color= Tolerance

The order of reading colors Body- End- Dot ↑ ↑ ↑ Numbers Coefficient

The order of reading resistance amount :

Tolerance+-(Coefficient*Numbers) tolerance color 4 colors

Coefficient color

Number color

2%= Red 5%= Golden 10%= silver

1= black 10= brown 100= red 1000= orange 10000= yellow 100000= Green 1000000= Blue 0.1= Golden

1= Brown 2= Red 3= Orange 4= Yellow 5= Green 6= Blue 7= Purple 8= Gray

0.01= Silver

9= white 0= black

tolerance color 5 color 0.1%= Purple 0.25%= Blue 0.5%= Green 1%= Brown 2%= Red

4- Six colors: it's like 5 colors and the sixth color is the characteristic of the thermal coefficient which its number is expressed in terms of PPM or centigrade degree.

The order of reading resistance amount

Tolerance+-(Coefficient*Numbers) 5PPM= Purple 10PPM= Blue 15PPM= Orange 25PPM= Yellow 50PPM= Red 100PPM= Brown

How to read resistance amount from the numeric and letter codes: 1- clear mode which means no code and password :Ohm and tolerance and even the allowed power (maximum power) of resistors are written on them. Such as : 15Ω 10% 2W 15ohm 2 watts resistor with 10% tolerance

330 ohm 10 wat resistor with 5% tolerance

2- 3 digit mode

4700Ω= 4.7 KΩ

3- 4 digit mode

176*104=1760000Ω=1.76MΩ

4- A Latin letter and several digit mode

22Ω

R= Ω= Ohm K=KΩ= Kilo Ohm M= MΩ= Mega Ohm Note: The Latin letter will be considered as decimal if it is placed between the digits or on the left side of the digits.

5- 2 Latin letters and several digit mode

10KΩ with 5% tolerance (error percent) 0.27Ω with 1% tolerance 3.3MΩ with 10% tolerance Note: The first Latin letter will be considered as decimal if it is placed between the digits or on the left side of the digits.

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first letter: resistance Range

second letter: tolerance

Ohm Ω =R Kilo Ohm KΩ =K Mega Ohm MΩ =M

0.1% =B 0.25% =C 0.5% =D ٪1 = F ٪2 = G ٪3 = H ٪5 = J ٪10 =K ٪20 =M

Concept of the tolerance (error percentage) of resistor: In the factory production line, making each resistor is associated with error. The accurate the resistor, the less its error percentage (tolerance). When resistor tolerance is said to be 5%, its amount will be calculated as follows. Error percentage+-resistance amount in terms of ohm For example, a 10KΩ resistor with 10% error is calculated like this 10%+-10000=10KΩ 10%of 10000 is 1000, so the resistor can vary from 9000Ω to 11000Ω 10000-1000=9000Ω 10000+1000=11000Ω

Standard amounts of resistors Several base numbers have been selected as standard from one tens of resistance (eg, 0 to 10 ohm) for example, in standard E6, six base numbers (1- 1.5- 2.2- 3.3-4.7-6.8) are the existing resistances of the standard. Letter E is taken from beginning of the word European. You can see the full chart of standards below :

8.20 3.00 9.10 1.69 3.01 5.36 9.53 1.30 1.74 2.32 3.09 4.12 5.49 7.32 9.76 1.14 1.32 1.52 1.76 2.03 2.34 2.71 3.12 3.61 4.17 4.81 5.56 6.42 7.41 8.56 9.88

6.80 6.80 2.70 8.20 1.62 2.87 5.11 9.09 1.27 1.69 2.26 3.01 4.02 5.36 7.15 9.53 1.13 1.30 1.50 1.74 2.00 2.32 2.67 3.09 3.57 4.12 4.75 5.49 6.34 7.32 8.45 9.76

5.60 2.40 7.50 1.54 2.74 4.87 8.66 1.24 1.65 2.21 2.94 3.92 5.23 6.98 9.31 1.11 1.29 1.49 1.72 1.98 2.29 2.64 3.05 3.52 4.07 4.70 5.42 6.26 7.23 8.35 9.65

4.70 4.70 2.20 6.80 1.47 2.61 4.64 8.25 1.21 1.62 2.15 2.87 3.83 5.11 6.81 9.09 1.10 1.27 1.47 1.69 1.96 2.26 2.61 3.01 3.48 4.02 4.64 5.36 6.19 7.15 8.25 9.53

3.90 2.00 6.20 1.40 2.49 4.42 7.87 1.18 1.58 2.10 2.80 3.74 4.99 6.65 8.87 1.09 1.26 1.45 1.67 1.93 2.23 2.58 2.98 3.44 3.97 4.59 5.30 6.12 7.06 8.16 9.42

3.30 3.30 1.80 5.60 1.33 2.37 4.22 7.50 1.15 1.54 2.05 2.74 3.65 4.87 6.49 8.66 1.07 1.24 1.43 1.65 1.91 2.21 2.55 2.94 3.40 3.92 4.53 5.23 6.04 6.98 8.06 9.31

2.70 1.60 5.10 1.27 2.26 4.02 7.15 1.13 1.50 2.00 2.67 3.57 4.75 6.34 8.45 1.06 1.23 1.42 1.64 1.89 2.18 2.52 2.91 3.36 3.88 4.48 5.17 5.97 6.90 7.96 9.20

2.20 2.20 1.50 4.70 1.21 2.15 3.83 6.81 1.10 1.47 1.96 2.61 3.48 4.64 6.19 8.25 1.05 1.21 1.40 1.62 1.87 2.15 2.49 2.87 3.32 3.83 4.42 5.11 5.90 6.81 7.87 9.09

1.80 1.30 4.30 1.15 2.05 3.65 6.49 1.07 1.43 1.91 2.55 3.40 4.53 6.04 8.06 1.04 1.20 1.38 1.60 1.84 2.13 2.46 2.84 3.28 3.79 4.37 5.05 5.83 6.73 7.77 8.98

1.50 1.50 1.20 3.90 1.10 1.96 3.48 6.19 1.05 1.40 1.87 2.49 3.32 4.42 5.90 7.87 1.02 1.18 1.37 1.58 1.82 2.10 2.43 2.80 3.24 3.74 4.32 4.99 5.76 6.65 7.68 8.87

1.20 1.10 3.60 1.05 1.87 3.32 5.90 1.02 1.37 1.82 2.43 3.24 4.32 5.76 7.68 1.01 1.17 1.35 1.56 1.80 2.08 2.40 2.77 3.20 3.70 4.27 4.93 5.69 6.57 7.59 8.76

E6 1.00 1.00 E12 1.00 E24 3.30 1.00 E48 1.78 3.16 5.62 1.00 E96 1.33 1.78 2.37 3.16 4.22 5.62 7.50 1.00 E192 1.15 1.33 1.54 1.78 2.05 2.37 2.74 3.16 3.65 4.22 4.87 5.62 6.49 7.50 8.66

The final problems of the chapter: -if 100 mA current flows through a 2.2 Kilo ohm resistor, what would the voltage at both sides be?

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V=R.I R= 2.2 KΩ=2200Ω I=100mA= 0.1A V=R.I= 2200*0.1=220 V=220V voltage of both sides of the resistor -If voltage of both sides of a 1 Kilo ohm resistor is 12 volt, calculate its current.

-Voltage of both sides of a resistor is 3.3 volt and its current is 30 mA. What is the amount of resistance?

-A 100 ohm resistor that can tolerate current of 0.3 amps is required in an electric

circuit.

The following resistors are available for choosing ? (100Ω-10w) and (100Ω-7.5w) and (100Ω-5w) which one should be chosen?

(100Ω-10w) resistor is better, because allowed wattage limit needs to be more than power 9. Two other resistors will burn on the circuit. -Calculate the allowed voltage of a 100 ohm resistor, if its allowed power is 2 watts?

-A flashlight LED with 300 MW power requires 50 mA to be able to turn ON. what is the LED's volt amount?

Evaluate your knowledge by answering the questions bellow: -What do you think is the difference between a 100 ohm ¼ watt resistor and a 100 ohm ½ watt resistor? Is it possible to place ¼ watt resistor in a circuit in which a ½ watt resistor is required? What about in reverse? -Calculate the amounts of E12 series resistors from 1 ohm to 100 ohm? -Calculate the amounts of resistors that are specified with following colors? First color Brown Brown Brown Red

First color Yellow Orange Brown Green

Second color Black Black Black Purple

Second color Purple White Gray Blue

Third color Brown Black Red Red

Third color Black Brown Green Black

Fourth color Golden Silver Red Golden

Fourth color Red Golden Orange Yellow

Fifth color Red Green Brown Blue

-According to the tolerance of each resistor of previous problem, specify the maximum and minimum ranges of each one?

1M5G= 1K8J= 1R2F= 4R7K= 68MM= 2K2B= 470RH= 560KD= 56KK= 6R8C= 47MN= RJ390=

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CAPACITOR Capacitor is probably the second most commonly used component in electronic circuits. A capacitor is a device that can temporarily store an electric charge. Capacitors come in several different varieties, the two most common being ceramic disk and electrolytic. The amount of capacitance of a given capacitor is measured in Farads designated by the symbol F.

DIODE A diode is a device that lets current flow in only one direction. A diode has two terminals, called the anode and the cathode. Current will flow through the diode only when positive voltage is applied to the anode and negative voltage to the cathode. If these voltages are reversed, current will not flow.

LIGHT EMITTING DIODE A light-emitting diode (LED) is a special type of diode that emits light when current passes through it. It is usually used as an indicator.

TRANSISTOR A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power. It is composed of semiconductor material usually with at least three terminals commonly called Base, Emitter, and Collector used for connection to an external circuit.

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ANTENNA An antenna is a transducer that converts radio frequency (RF) fields into alternating current or vice versa. There are both receiving and transmission antennas for sending or receiving radio transmissions. Antennas play an important role in the operation of all radio equipment. They are used in wireless local area networks, mobile telephony and satellite communication.

MICROPHONE A microphone, colloquially nicknamed mic or mike, is a transducer that converts sound into an electrical signal.

LOUDSPEAKER A loudspeaker is an electroacoustic transducer which converts an electrical audio signal into a corresponding sound.

RELAY SWITCH Relays are switches that open and close circuits electromechanically or electronically. Relays control one electrical circuit by opening and closing contacts in another circuit. There is an open contact when the relay is not energized.

TRANSFORMER A transformer is an electrical device that transfers electrical energy between two or more circuits through electromagnetic induction. It can also be said to be an electrical device that steps-up an steps-down electrical current.

BRIDGE RECTIFIER A bridge rectifier is a type of full wave rectifier which uses four or more diodes to efficiently convert AC to DC.

FUSE A fuse is an electrical safety device that operates to provide over current protection in a circuit. It's an essential component that must be present in both Electrical and Electronic appliances.

BATTERY A battery is a device consisting of one or more electrochemical cells with external connections provided to power electrical devices.

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INDUCTOR An inductor, also called a coil, choke or reactor, is a passive two-terminal electrical component that stores electrical energy in a magnetic field when electric current flows through it.

SWITCH A switch is an electronic component or device that can switch an electrical circuit, interrupting the current or diverting it from one conductor to another.

INTEGRATED CIRCUIT An integrated circuit is a special component that contains an entire electronic circuit, complete with transistors, diodes, and other elements, all photographically etched onto a tiny piece of silicon.

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