compilation of task and projects in consumer

compilation of task and projects in consumer
This compilation was created as a tribute and response to the leanings that I have got in this electronic vocational
course. This will also serve as a practical guide for beginners in this field. The main objective of this reading material is to
help students in understanding and learning electronics in an easier way. Further, i intend to awaken the interest not
only of the students, but also of others who are definitely exposed and involved to advance technology.
This compilation is equipped with instructions and illustrations that would help students and readers in resolving
problems regarding troubleshooting.
Nonetheless, even though, this reference contains reliable information, still, the reader must undergo adequate and
proper training in order to correctly apply theoretical and scientific knowledge that were included in this book.
I would like to thank Mr. Leo Diche
for his help and support
and for his perseverance in teaching me.
Electronics deals with electrical circuits that involve active electrical components such as vacuum tubes, transistors, diodes
and integrated circuits, and associated passive interconnection technologies. The nonlinear behaviour of active components and
their ability to control electron flows makes amplification of weak signals possible and electronics is widely used in information
processing, telecommunications and signal processing. The ability of electronic devices to act as switches makes digital information
processing possible. Interconnection technologies such as circuit boards, electronics packaging technology, and other varied forms
of communication infrastructure complete circuit functionality and transform the mixed components into a working system.
Electronics is distinct from electrical and electro-mechanical science and technology, which deals with the generation,
distribution, switching, storage and conversion of electrical energy to and from other energy forms using wires, motors, generators,
batteries, switches, relays, transformers, resistors and other passive components. This distinction started around 1906 with the
invention by Lee De Forest of the triode, which made electrical amplification of weak radio signals and audio signals possible with a
non-mechanical device. Until 1950 this field was called "radio technology" because its principal application was the design and
theory of radio transmitters, receivers and vacuum tubes.
Today, most electronic devices use semiconductor components to perform electron control. The study of semiconductor
devices and related technology is considered a branch of solid state physics, whereas the design and construction of electronic
circuits to solve practical problems come under electronics engineering. This article focuses on engineering aspects of electronics.
By maintaining a safe working practice you will protect not only your own safety but that of others who will come into
contact with your work.
Always ensure grounding straps and leads are intact and securely connected.
Always use the correct fire extinguisher. Water can conduct electric currents, Carbon dioxide (CO2) and appropriate
Halogenated extinguishers should be used and in some cases foam is appropriate.
Always ensure interlock switches are operating properly
Always ensure your tools and test equipment are kept clean, in good working order and always use the appropriate
tool for the job.
Always discharge capacitors in a circuit. Some capacitors such as those in a power supply will hold a lethal charge long
after the power has been removed.
Always familiarise yourself with the safety precautions associated with any solvents or chemicals you are about to
use. Many give off strong fumes which can ignite or cause drowsiness.
Always use appropriate tools, equipment and protective clothes, Buy the best you can afford.
Always use the recommended replacement component, many devices have built in safety measures and narrow
tolerance bands.
Always wear protective equipment, protective boots, hard-hats, goggles, overalls etc when they are needed.
Always remove all rings, bracelets, medallions or anything which could get caught in moving machinery or may
conduct electricity.
Always read the manufacturers data and information sheets. They are an invaluable source of information and safety
procedures for the equipment under test.
Always when working with electricity, keep your left hand in your pocket where possible to avoid providing an
electrical path through your chest and heart.
Do not work when you are tired or taking medicine which makes you drowsy or affects your reactions and
Do not work under poor lighting conditions
Do not work in areas which are damp
Never use an extension or adapter to overcome grounding straps or earth leads.
Never work in wet clothing
Never assume a circuit is off. Always check for power with the appropriate instrument.
Never meddle with safety devices
Never override interlock safety switches.
Never remove equipment grounding straps or leads.
- Electrical potential, or voltage, is the force or electrical energy required to move electrons from one place to another.
Symbol for Voltage: Letter E
Unit of measurement: Volt
Symbol for unit of measurement: Letter V
The difference in electrical potentials between two points in an electric field (the space surrounding an electric
charge) is known as the electrical potential difference. This difference is proportional to the electrostatic force that tends to
push electrons or other charge carriers from one point to the other. Potential difference, electrical potential, and
electromagnetic force are measured in volts, leading to the commonly used term voltage.
To have an electrical energy source, such as a battery, one terminal must be more positive or more negative than the
other. This condition may be referred to as a difference of potential, an electromotive force, a potential, or a voltage. All of the
terms are correct; however, voltage is the most commonly used.
Battery terminals (or any other points) having unequal electrical charges have the capacity to move electrical charges
through a resistance because of this difference of potential energy. An automobile battery has an electromotive force, potential
difference, or voltage of 12 volts. It is correct to say that the automobile battery voltage equals 12 volts, or E = 12 Volts.
- Electric current flow is the movement of free electrons through a conductor. The rate of movement is measured in
amperes. One ampere represents the movement of a specific number of electrons (6.28 x 1018 electrons = 1 coulomb =
unit of electric charge) past a certain point in a conductor in one second.
Symbol for Current: Letter I
Unit of measurement: Ampere
Symbol for unit of measurement: Letter A
When controlled by an external force, the electrons move generally in the same direction. The effect of this movement
is felt almost instantly from one end of the conductor to the other. The electron movement is called electric current.
Electric current, defined historically as conventional current, is the term used for current flow from the most positive
part of a circuit to the most negative part. However, to simplify circuit analysis, most electronics illustrations depict “electron
current” flow from the most negative part of a circuit to the most positive part since it is only the negatively charged electrons
that actually flow.
It should be noted that depending on the conditions, an electric current can consist of a flow of charged particles in either
direction or even in both directions at once.
A direct current (DC) is a unidirectional flow, while an alternating current (AC) reverses direction repeatedly.
Resistance is the opposition a device or material offers to the movement of electrons and is measured in ohms.
Symbol for resistance: Letter R
Unit of measurement: Ohms
Symbol for unit of measurement: Greek Letter Omega (Ω)
When there is current in a material, the free electrons move through the material and occasionally collide with atoms. These
collisions cause the electrons to lose some of their energy and restrict their movement. The more collisions mean the more
opposition to the flow of electrons. The higher the resistor value, the greater the opposition to current flow.
- Electrical impedance, or simply impedance, is a measure of the combined opposing forces to an alternating electric
Symbol for impedance: Letter Z
Unit of measurement: Ohms
Symbol for unit of measurement: Greek Letter Omega (Ω)
Unlike electrical resistance even though both are measured in ohms, the impedance of an electric circuit can be a
complex number because it is determined by the vector sum of a circuit’s resistance, capacitive reactance, and inductive
- Electric power is the rate at which electrical energy is produced or consumed and is measured in watts.
Symbol for Power: Letter P
Unit of Measurement: Watt
Symbol for unit of measurement: Letter W
Energy is typically defined as the ability to do work or, more specifically, the work resulting from a force acting on
mass over a distance. Electrical energy is the energy that’s stored in an electric field or transported by an electric current.
Some examples of electrical energy include:
 The energy that is constantly stored in the earth’s atmosphere and is partly released during a thunderstorm in the
form of lightning.
 The energy that is stored in the coils of an electrical generator in a power station and is then transmitted by wires to
the consumer; the consumer then pays for each unit of energy received.
 The energy that is stored in a capacitor and can be released to drive a current through an electrical circuit.
The operation of electrical circuits involves force (voltage) acting on mass (electrons) over a distance.
As mentioned, energy is the capacity to do work, so in electrical circuits, energy is transformed into heat energy. When
electrons flow through a conductor, the free electrons lose energy as they collide with atoms in the material. When there is
current through a resistor, energy is converted to heat.
Power, therefore, can be viewed as the measure of how much energy is being converted to heat.
A common example of this is the light bulb. The current through the filament that produces light also produces heat because
the filament has some opposition to current. All electrical devices dissipate or consume power. When an electrical component
such as a light bulb or a stereo is connected to and draws current from a voltage source, the component is considered a load on
that voltage source.
Every load device has a certain amount of resistance. This is load resistance. Load resistance is the resistance or
opposition of the load device to current. Load current is the current drawn from the voltage source by the load device.
- Inductance is an effect which results from the magnetic field that forms around a current-carrying conductor.
Electrical current through the conductor creates a magnetic flux proportional to the current. A change in this current
creates a change in magnetic flux that, in turn, generates an electromotive force (EMF) that acts to oppose this change
in current. Inductance is a measure of the generated EMF for a unit change in current.
Symbol for Inductance: Letter L
Unit of Measurement: Henry
Symbol for unit of measurement: Letter H
- Capacitance is a measure of stored energy between two conductive electrodes, or plates, separated by an insulator
(otherwise known as a capacitor). A capacitor can store electric energy when disconnected from its charging circuit,
so it can be used like a temporary battery.
Symbol for Capacitance: Letter C
Unit of Measurement: Farad
Symbol for unit of measurement: Letter F
- Reactance is the imaginary part of impedance and is caused by the presence of inductors or capacitors in the circuit.
Reactance produces a phase shift between the electric current and voltage in the circuit.
Symbol for Reactance: Letter X
Unit of Measurement: Ohms
Symbol for unit of measurement: Greek Letter Omega (Ω)
Inductive reactance (symbol XL) is caused by the fact that a current is accompanied by a magnetic field; therefore, a
varying current is accompanied by a varying magnetic field––the latter gives an electromotive force that resists the changes in
current. The more the current changes, the more an inductor resists it: the reactance is proportional to the frequency (hence
zero for DC). There is also a phase difference between the current and the applied voltage.
Capacitive reactance (symbol XC) reflects the fact that electrons cannot pass through a capacitor, yet effectively
alternating current can: the higher the frequency the better. There is also a phase difference between the alternating current
flowing through a capacitor and the potential difference across the capacitor’s electrodes.
- An electrical component is any component used in the generation, transmission, distribution, or consumption of
electric power. The minimum requirements for a simple circuit are a power source, load device(s), and conductor(s).
However, additional circuit components are usually added to provide control, protection, and monitoring capabilities.
All electronic circuits require some source of energy in order to operate. Some of the more common sources for providing
power are batteries, generators, and power supplies.
- A battery is a device that converts chemical energy to electrical energy. A multicellular battery consists of two or more
cells in a series (connected end-to-end). The negative terminal of one cell is connected to the positive terminal of
another cell and so on to increase the battery’s voltage potential. Batteries can also be wired in parallel to increase
their capacity.
- An electrical generator is a device that converts mechanical energy to electrical energy, generally using the principle
of electromagnetic induction. A force is required to provide the mechanical energy necessary to turn the rotor shaft of
the generator and produce an electrical output. The driving force producing this mechanical energy input is called the
prime mover. The prime mover can be any source of rotary motion such as that provided by waterfalls, windmills,
steam engines, diesel engines, aircraft engines, or nuclear driving sources. Generator output is independent of the
type of prime mover used, other than the requirement for a relatively constant rotational speed. A generator’s output
voltage is controlled by a voltage regulator. A voltage regulator changes the output voltage by varying the resistance
of the generator’s field circuit. Generators are rated in voltage amperes; in other words, how many volts they can
produce at how many amps per phase.
- A power supply, sometimes known as a power supply unit (PSU), is a device or system that supplies electrical or other
types of energy to an output load or group of loads. The term is most commonly applied to electrical energy supplies
such as rectifiers and inverters. Rectifiers are used to convert AC to DC while inverters are used to convert DC to AC.
A load is any device or circuit that absorbs power. Appliances plugged into a wall outlet are common examples of load devices.
There are many electrical components that fit into this category, so we will only discuss a few of the main ones.
- A lamp produces light from electricity and is often used to provide a visual indication of current flow. There are a wide
variety of lamps used in electronics from standard filament-type lamps to light emitting diodes (LED).
- A resistor is a passive device used to regulate current in a circuit. Electronic equipment uses a wide variety of
resistors made of resistive wire, metal film, or carbon composition. The two most common types of resistors are fixed
and variable.
Many fixed resistors use a pattern of four, five, or six colored stripes (or bands) painted around the body of the
resistor to indicate their resistance and tolerance values.
The variable resistor is a resistor whose resistance value can be adjusted, which in turn allows a circuit’s current
value to be increased or decreased. Variable resistors, also called potentiometers or rheostats, are operated by turning
a shaft or sliding a control. A common use of variable resistors is for dimming lights.
- Inductors are passive devices commonly used in signal processing circuits for their property of inductance, which, as
you may recall, oppose changes in current. An inductor is usually constructed as a coil of conducting material,
typically copper wire, wrapped around a core either of air or of ferromagnetic material. Core materials with a higher
permeability than air confine the magnetic field closely to the inductor, thereby increasing the inductance. The
opposition offered by a coil to the flow of alternating current is called inductive reactance.
- A capacitor is a passive electrical device that opposes changes in voltage and can be used to store energy in the
electric field between a pair of closely spaced conductors called plates. When voltage is applied to the capacitor,
electric charges of equal magnitude, but opposite polarity, build up on each plate. They can also be used to
differentiate between high-frequency and low-frequency signals, and this makes them useful in electronic filters.
Semiconductor devices are electronic components that exploit the electronic properties of certain Semi-conductive materials–
–typically silicon, germanium, and gallium arsenide. They use electronic conduction in the solid state by introduction of an
electric field or from exposure to light, pressure, or heat; thus, semiconductors can make excellent sensors.
- A diode is an active component that restricts the direction of movement of charge carriers. Essentially, it allows an
electric current to flow in one direction but blocks it in the opposite direction. Thus, the diode can be thought of as an
electronic version of a check valve.
- A transistor is a semiconductor device that uses a small amount of voltage or electrical current to control a larger
change in voltage or current. A transistor can be thought of as an electronic version of a switch and is the fundamental
building block of the circuitry that governs the operation of all modern electronics.
Electromagnetic devices exploit the properties of the region of space where electric charges experience a physical influence.
This region is commonly called the electromagnetic field. The term electromagnetism comes from the fact that electrical and
magnetic forces are involved simultaneously. The phenomenon of electromagnetic induction, which provides for the operation
of electrical generators, induction motors, and transformers, is based on the principle that a changing electric field generates a
magnetic field. Similarly, a changing magnetic field produces an electric field.
A transformer is a device that is used to transfer electrical energy from one circuit to another by means of an
electromagnetic field. One circuit is connected to a power source and is referred to as the primary. The other circuit is
connected to a load device and is referred to as the secondary. Transformers operate using the principles of mutual
induction and electromagnetism as there are no direct connections between the primary and secondary windings. A
transformer may perform several functions depending on its purpose in the circuit; it may increase (step up) voltage
and decrease the current, decrease (step down) voltage and increase current, isolate circuits, match impedance of
different circuits, or shift phases between circuits. Accordingly, transformers come in a range of sizes and can be
classified in many ways such as by its power level, frequency, voltage class, or by a ratio of the amount of voltage
required to step up or down.
Relays and solenoids are used for controlling or switching electrical circuits from a remote location. The primary
circuit is the controlling or actuating circuit. The current flow that energizes the coil of the relay is the primary
current. The secondary circuit is the controlled circuit. A relay’s contacts are made to close or open. Closed contacts
provide continuity in the controlled or secondary circuit of a relay; open contacts remove continuity from the
secondary circuit. The configuration of contacts available may offer one or many secondary circuit paths. One possible
application of a relay is to use a single primary current path to control several secondary current paths.
Electric motors convert electrical energy into mechanical energy. They come in many types and sizes that allow them
to perform different tasks. They work on the principle that electrical energy develops a magnetic field that produces a
mechanical force. The mechanical force of attraction and repulsion rotates a shaft 360 degrees. DC motors are
commonly used in battery-operated devices such as drills, shavers, toys, or larger items, such as a golf cart. They are
also found in some AC devices after being rectified for use in low-voltage applications such as video cassette recorders
and compact disc players.
Of course, simply having a power source and load device does not make a circuit. They must be connected for continuity. This
is usually accomplished by wiring or soldering the components together resulting in a closed loop. On electronic drawings, or
schematics, wires are illustrated as the line(s) that connect two or more components together.
A wire is a single, usually cylindrical, elongated strand of drawn metal.
There are several types of wiring used to carry electricity and telecommunications signals.
SOLID – solid wire or solid-core wire consists of one piece of metal wire.
STRANDED - Stranded wire is composed of a bundle of small-gauge wires wrapped in a particular pattern inside insulation to
make a larger conductor. Stranded wire is more flexible than a solid strand of the same overall gauge.
CABLES - Cables are two or more wires that are bound together, typically in a common protective jacket or sheath.
TWISTED PAIRS - Twisted-pair cabling is a form of wiring in which two conductors are wound together for the purposes of
cancelling out radio frequency interference and electromagnetic interference (RFI/EMI) from external sources and cross talk
from neighboring wires.
COAXIAL - Coaxial cable is made up of two wires: a wire conductor in the center and a circumferential outer conductor with
an insulator separating the two conductors. The dimension and material of the conductors and insulation determine the
cables’ characteristic impedance and attenuation at various frequencies.
FIBER-OPTIC – Fiber-optic cables are not made out of metal but rather glass or plastic fibers that are designed to guide light
along the fiber length by total internal reflection. A layer of cladding surrounds the fiber to redirect light and keep it within the
core. Fiber-optic cables are often used as a medium for telecommunication and networking because they offer the advantages
of improved bandwidth and noise immunity over traditional types of wiring.
Soldering is a method of joining metal parts using a filler material (solder) that has a low melting point, typically below 450
degrees Celsius (450° C) (842° Fahrenheit [F]). In the soldering process, heat is applied to the parts to be joined causing the
solder to melt and be drawn into the joint by capillary action. The most frequent application of soldering is assembling
electronic components to printed circuit boards (PCB). PCBs are used to mechanically support and electrically connect
electronic components using conductive pathways, or traces, etched from copper sheets laminated onto a nonconductive
Control devices allow the operator to control the aspects of the circuit’s operation. The most common control device is the
switch. A switch is a device for changing the flow of current in a circuit; a switch, when closed, provides zero resistance to the
circuit while an open switch introduces an infinite amount of resistance. Switches are commonly used to apply power or to
control a certain function of a circuit. There are several types of switches, but you will primarily be concerned with single-pole
single-throw (SPST), single-pole double-throw (SPDT), and double-pole double-throw (DPDT) switches.
- An SPST switch is a simple on-off switch, such as a light switch, that either opens or closes the circuit. The P refers to
the term pole, which is the movable portion or arm of the switch. The T is the throw, which identifies the number of
circuits that the pole opens or closes when the switch is operated.
- An SPDT switch is a toggle switch that provides a continuity path to one of two possible circuits. Figure 1–10 shows
the switch, or “bat” that toggles between one of the two circuit paths. An example of a SPDT switch is an AM/FM
selector switch on a radio.
- A DPDT switch provides twice the options as a SPDT switch. It could be used to connect two circuits together by
throwing one switch that is mechanically connected as illustrated by the dashed line.
Protective devices provide current limiting with the purpose of protecting circuits from the harmful effects of excess current
flow. Excess current, if permitted to flow, can cause circuitry to become hot and melt, resulting in an open circuit and possibly
damaging components along the way. Current limiters can reduce the peak current flowing in a circuit by taking the excess
current for a short period until the fault clears or until additional protective devices activate. The most common protective
devices are fuses and circuit breakers.
- A fuse is a type of overcurrent protection device. Its critical component is a thin metal wire that will melt when heated
by a prescribed electric current, opening the circuit of which it is a part, and so protecting the circuit from an
overcurrent condition. Fuses are rated with current and voltage ratings that indicate the maximum circuit current and
voltage in which the fuse can be used. Fuses should be replaced with only suitable substitutes even though many fuses
are physically the same size. You can replace a blown (open) fuse with another having the same size, voltage, and
current characteristics, or it is permissible to use one with a larger voltage rating and/or a smaller current rating. For
example, fuses carrying a 250V rating can be safely used in a 125V circuit, but a 125V fuse cannot be used in a 250V
circuit as the fuse may not be capable of safely interrupting the arc in a circuit of a higher voltage. Conversely, fuses
carrying a 2 amp rating can be safely used in a 5 amp circuit, but a 5 amp fuse cannot be used in a 2 amp circuit.
- A circuit breaker serves the same purpose as a fuse, but it works a little differently. When excessive current passes
through a circuit breaker, it energizes and creates a break in the circuit. When this happens, the circuit breaker is said
to have “tripped” or “popped.” An advantage of the circuit breaker over the fuse is the ability to reset and reuse the
circuit breaker after the overload has been removed, while the fuse must be replaced.
- Ground is a point in a circuit used as a common reference point from which voltages are measured. Voltages may be
either positive or negative with respect to ground, which has a potential of zero volts. You are probably familiar with
the electrical ground on an automobile where the chassis is the common reference point. Ground may be either an
earth ground, which means that point has been connected to a metal stake driven into the earth; or as in the case of
most electronic equipment, the ground symbol denotes the metal chassis. When completing each electrical circuit,
common points are connected directly to the metal chassis; current flows through the metal chassis (conductor) to
each other points of the circuit.
Basically these are the primary tools when you are going to repair cell phones.
1. Multi-Tester ( Analog/Digital)- Used to measure Voltages, Currents and Resistance in electronic components.
2. Screwdrivers - Used to loosen the phones screws.
3. Tweezers - used to hold and pick small cell phone component parts.
4. Soldering iron - used to solder / re-solder electronic parts.
5. Soldering lead - used to bonds Electronic components.
6. Soldering Flux and Paste - Used to tightened soldering quality.
7. BGA Rework station - Applied Heat to remove and replaced parts and IC chips.
8. Re balling Kits - Tools for re balling IC bumps, this composed of Stencil plates, Ball Leads and Spatula
9. DC Regulated Power Supply- Used to substitute battery voltage when working on hardware troubleshooting.
10. Flashing and Unlocking Device- it is a Software Tool that is used to unlock and flash mobile phones
programmable circuits.
11. Cables and Wires - Used as an Interface from PC to cell phones when working on like flashing, unlocking and jail
Indicator Zero Connector
Indicator Pointer
Indicator Scale
Continuity Indicating
Range Selector Switch knob
0-ohms adjusting knob
/0- centering meter
(NULL meter) adjusting knob
6. Measuring Terminal +
7. Measuring Terminal - COM
8. Series Terminal Capacitor OUTPUT
9. Panel
11. Rear Case
1.) Resistance (OHMS) scale
2.) DCV, A scale and ACV scale
(10V or more)
3.) 0-centerig (NULL) +/- DCV scale
4.) ACV 2.5 (AC 2.5V) exclusive scale
5.) Transistor DC amplification factor
(hFE) scale
6.) 1.5 battery test (BATT 1.5V)
7.) OHMS range terminal to terminal
(Li) scale)
8.) OHMS range terminal to terminal
(LV) scale
9.) Decibel (dB) scale
10.) Continuity Indicating LED
11.0 Mirror: To obtain most accurate
readings, the mirror is devised to make
operator eyes, the indicator pointer, and
the indicator pointer reflexed to the
mirror put together in line.
Master Appliance Soldering Iron
Damp Sponge
Modeler’s Vise or Frame
Flux to remove oxides
If we wasp one size miniature serial loudspeaker (8 ohm speaker) suits, Flashing LED number FRL – 4403 will lighten and can
blink. But it must not use other equipment help unless, power supply is given with it only. You will already hear the sound
goes out the loudspeaker in the rhythm that it works with.
NE555 timer IC
2.2k ohm resistor
15k ohm resistor
0.01 uF ceramic capacitor
C2, C3
220 uF electrolytic capacitor
470 uF electrolytic capacitor
D1, D2
1N4002 diode
All resistors are 5 or 10 percent tolerance, 1/4-watt
all capacitors are 10 percent tolerance
This circuit roughly doubles the voltage of the input,
however the current output is low. Doubled output is at 'V
A switched-mode power supply (switching-mode power supply, SMPS, or simply switcher) is an electronic power
supply that incorporates a switching regulator in order to be highly efficient in the conversion of electrical power. Like other
types of power supplies, an SMPS transfers power from a source like the electrical power grid to a load (such as a personal
computer) while converting voltage and current characteristics. An SMPS is usually employed to efficiently provide a regulated
output voltage, typically at a level different from the input voltage.
Unlike a linear power supply, the pass transistor of a switching mode supply continually switches between low-dissipation,
full-on and full-off states, and spends very little time in the high dissipation transitions (which minimizes wasted energy).
Ideally, a switched-mode power supply dissipates no power. Voltage regulation is achieved by varying the ratio of on-to-off
time. In contrast, a linear power supply regulates the output voltage by continually dissipating power in the pass transistor.
This higher power conversion efficiency is an important advantage of a switched-mode power supply. Switched-mode power
supplies may also be substantially smaller and lighter than a linear supply due to the smaller transformer size and weight.
A voltage regulator is designed to automatically maintain a constant voltage level. A voltage regulator may be a simple "feedforward" design or may include negative feedback control loops. It may use an electromechanical mechanism, or electronic
components. Depending on the design, it may be used to regulate one or more AC or DC voltages.
Electronic voltage regulators are found in devices such as computer power supplies where they stabilize the DC voltages used
by the processor and other elements. In automobile alternators and central power station generator plants, voltage regulators
control the output of the plant. In an electric power distribution system, voltage regulators may be installed at a substation or
along distribution lines so that all customers receive steady voltage independent of how much power is drawn from the line.
Measures of regulator quality
The output voltage can only be held roughly constant; the regulation is specified by two measurements:
load regulation is the change in output voltage for a given change in load current (for example: "typically 15 mV,
maximum 100 mV for load currents between 5 mA and 1.4 A, at some specified temperature and input voltage").
line regulation or input regulation is the degree to which output voltage changes with input (supply) voltage
changes - as a ratio of output to input change (for example "typically 13 mV/V"), or the output voltage change over the
entire specified input voltage range (for example "plus or minus 2% for input voltages between 90 V and 260 V, 5060 Hz").
An audio power amplifier is an electronic amplifier that amplifies low-power audio signals (signals composed primarily of
frequencies between 20 - 20 000 Hz, the human range of hearing) to a level suitable for driving loudspeakers and is the final
stage in a typical audio playback chain.
The preceding stages in such a chain are low power audio amplifiers which perform tasks like pre-amplification, equalization,
tone control, mixing/effects, or audio sources like record players, CD players, and cassette players. Most audio power
amplifiers require these low-level inputs to adhere to line levels.
While the input signal to an audio power amplifier may measure only a few hundred microwatts, its output may be tens,
hundreds, or thousands of watts.
Mission Cyrus 1 Hi Fi integrated audio amplifier (1984)
The task of an audio amplifier is to take a small signal and make it bigger without making any other changes in it. This is a
demanding task, because
a musical sound usually contains several frequencies, all of which must be amplified by the same factor to avoid changing the
waveform and hence the quality of the sound. An amplifier which multiplies the amplitudes of all frequencies by the same
factor is said to be linear. Departures from linearity lead to various types of distortions.
The operational details of amplifiers are buried in the field of electronics, but for audio purposes it is usually safe to say that
current commercial audio amplifiers are so good that a normally operating amplifier is seldom the limitation on the fidelity of
a sound reproduction system. One must be sure that the amplifier can provide enough power to drive the existing
loudspeakers, but otherwise amplifiers are typically one of the most trouble-free elements of a sound system.
The amplitudes of all frequencies within an amplifier's operating range must be amplified by the same factor to avoid
distortion. An amplifier which satisfies this requirement is said to be perfectly linear. If the peaks of the waveform are clipped,
this gives rise to what is called harmonic distortion. Another type of distortion is intermodulation distortion, which occurs
when different frequencies in the signal mix to produce sum and difference frequencies which didn't exist in the signal.
Transient distortion occurs when amplifier components cannot handle the rate of change of the signal, for example in rapid
percussive attacks. There is also transient intermodulation distortion (TIM) to which modern integrated circuits are
susceptible. Such circuits depend upon feedback for their linearity, but time delays in the feedback can cause intermodulation
distortion on fast transients in the signal.
This is the circuit diagram of a fully transistorized sub woofer amplifier that can produce an output of 100W.There are seven
transistors including four in the output stage. The transistors Q1 and Q2 form the preamplifier stage. Transistors Q4 to Q7
form the output stage. Since no ICs are used the circuit is very robust and can be easily assembled on a general purpose PCB.
Circuit diagram with Parts list.
The circuit can be powered from a +35V/-35V, 5A dual power supply.
Use a 100W, 12 inch sub woofer at the output.
All electrolytic capacitors must be rated 100V.
The transistor Q4 to Q7 must be fitted with heat sinks.
IR detectors are little microchips
with a photocell that are tuned to
listen to infrared light. They are
almost always used for remote
control detection - every TV and
DVD player has one of these in the
front to listen for the IR signal
from the clicker. Inside the remote
control is a matching IR LED, which
emits IR pulses to tell the TV to
turn on, off or change channels. IR
light is not visible to the human
eye, which means it takes a little
more work to test a setup.
COLOR TELEVISION is part of the history of television, the technology of television and practices associated with television's
transmission of moving images in color video.
In its most basic form, a color broadcast can be created by broadcasting three monochrome images, one each in the three
colors of red, green and blue (RGB). When displayed together or in rapid succession, these images will blend together to
produce a full color image as seen by the viewer.
One of the great technical challenges of introducing color broadcast television was the desire to conserve bandwidth,
potentially three times that of the existing black-and-white (B&W) standards, and not use an excessive amount of radio
spectrum. In the United States, after considerable research, the National Television Systems Committee approved an allelectronic system developed by RCA which encoded the color information separately from the brightness information and
greatly reduced the resolution of the color information in order to conserve bandwidth. The brightness image remained
compatible with existing B&W television sets at slightly reduced resolution, while color televisions could decode the extra
information in the signal and produce a limited-resolution color display. The higher resolution B&W and lower resolution
color images combine in the eye to produce a seemingly high-resolution color image. The NTSC standard represented a major
technical achievement.
Vertical lock lost:
This indicates a picture that is correct but rolling vertically. If the picture is rolling down the screen the frequency of the
verticaloscillator is incorrect - too high - and this may be the problem. Generally,the free run frequency of the vertical
oscillator should be a little belowthe video rate (of around 50 or 60 Hz depending on where you live). If it is rolling
continuously without jumping, then there is a loss ofsync from the sync separator or faulty components in the vertical
oscillatorcausing it to totally ignore the sync pulses. If it is rolling up rapidly and not quite able to remain locked, the freerun
frequency may be too low or there could be a fault in the sync circuits resulting in an inadequate vertical pull-in range. On
older sets, there was actually a vertical hold (and possibly even aSeparate vertical frequency) control. On anything made in the
last decade, this is unlikely. There may be Vertical Frequency and Vertical Pull-in Range adjustments (and others) accessible
via the service menu. However, if any of these ever change, it indicates a possible problem with the EEPROMlosing its memory
as component drift is unlikely. As with everything else, bad connections are possible as well. You will need a schematic and
possibly setup info to go beyond this.
Vertical squashed:
This is a vertical deflection problem - possibly a bad capacitor, badconnection, flyback/pump up diode, or other component.
None of these should be very expensive (in a relative sort of way). If the symptoms change - particularly if they become less
severe - as the set warms up, a dried up electrolytic capacitor is most likely. If they get worse, it could be a bad semiconductor.
Freeze spray or a heat gun may be useful in identifying the defective component. It is often easiest to substitute a good
capacitor for each electrolytic in the vertical output circuit. Look for bad connections (particularly to the deflection yoke), then
consider replacing the vertical output IC or transistor(s). A defective deflection yoke is also possible or in rare cases, a bad
yoke damping resistor (e.g., 500 ohms, may be mounted on the yoke assembly itself). The following are NOT possible: CRT,
flyback, tuner (except for the famous RCA/GE/Proscan or Sony models where the controller is at fault - see the sections on
these specific brands). I am just trying to think of really expensive parts that cannot possibly be at fault :-). Note that some
movies or laser karaoke discs are recorded in 'letterbox'format which at first glance looks like a squashed vertical problem.
However, the picture aspect ratio will be correct and turning up the brightness will reveal a perfectly normal raster above and
below the picture.
Part of picture cut off:
The following applies if the part of the picture is missing but nototherwise squashed or distorted. For example, 85% is missing
but theportion still visible is normal size. Wow! That's an interesting one, more so than the typical run-of-the-mill"my TV just
up and died on me". Or, "my pet orangutan just put a holein the CRT, what should I do"? Since the size of the picture fragment
is correct but 85% is missing,my first thought would be to check waveforms going into the verticalOutput stage. The supply
voltage is probably correct since that oftenDetermines the size. It almost sounds like the waveform rather thanbeing mostly on
(active video) and off for the short blanking periodis somehow only on during the last part of the active video thus givingyou
just the bottom of the picture. If there is a vertical output IC,it may be defective or the blanking input to it may be corrupted.
Theproblem may be as far back as the sync separator. Then again who knows,maybe wait for the schematics.
Single Vertical Line:
CAUTION: To prevent damage to the CRT phosphors, immediately turn down the brightness so the line is just barely visible. If
the user controls do not have enough range, you will have to locate and adjust the master brightness or screen/G2 pots. Since
you have high voltage, the horizontal deflection circuits are almost certainly working (unless there is a separate high voltage
power supply - almost unheard of in modern TVs and very uncommon in all but the most expensive monitors). Check for bad
solder connections between the main board and the deflection yoke. Could also be a bad horizontal coil in the yoke, linearity
coil, etc.There is not that much to go bad based on these symptoms assuming the high voltage and the horizontal deflection use
the same fly back. It is almost certainly not an IC or transistor that is bad.
From: "Phil Nelson"
Subject: horizontal problem (or not?) in National TV-7W
tube until I can get a little more adjustment out of it? Or is
barking up the wrong tree?
After much work, I have a good picture on my National TV7W television.
If I turn up the brightness enough to show some retrace
lines, however,
a faint vertical bar appears at the left of the screen.
The actual picture looks considerably better than this
blurry off-air
snapshot. If I turn down the brightness a bit, this problem
is masked, but
it's distracting when changing channels. The ideal
tune adjustment for one channel won't necessarily give the
best picture on
another station. Which brings up other questions involving
AGC and
alignment, but . . .
It's almost as if the scan flies a little "too far left" before
back in sync. If I reduce the brightness to make the retrace
disappear, this problem disappears. Horizontal and
vertical lock are
very stable.
Here is the schematic for the TV's horizontal section.
The vertical bar doesn't appear to contain any data. This
looks more like a
retrace issue.
A little while ago, I adjusted the drive trimmer cap on pin 4
of the
horizontal output tube to correct a horizontal linearity
that caused the picture to be too squished and bright on
the right side.
The 4.7 meg resistor on pin 4 has been replaced, but the
two 47K
resistors have not been replaced. The trimmer is turned as
far as it
can go at this point. Should I mess with other components
on the output
----------From: "Brenda Ann"
That's the horizontal blanking interval... it's the same as
the vertical
blanking interval, but at horizontal frequency (the bar you
see when the
picture 'rolls'). Normally, I have seen this bar on the right
side of the
screen, but depending upon the peculiarities of your
horizontal sync
circuit it could sit on the left as well. It's not a big deal, but
you can
try adjusting your horizontal hold to see if the bar
----------From: Robert Casey
Looks like a phase error. That is, the phase of the
horizontal oscillator's
output is off in terms of time compared to the video signal.
Looks like the
oscillator is a few microseconds too early in commanding a
retrace. There
usually are RC circuits to separate the horizontal sync from
the vertical
sync, and if one or more parts in those RC circuits are way
off, could
cause phase errors.
Or a bad resistor in the oscillator could do it. I assume you
replaced all
the wax caps. Don't use ceramic caps though, temperature
drift can mess
up horizontal oscillators.
It's also possible that the designers expected you to over
scan the image
more. C78, R33, R10 and R35 may be making a variable
phase shifter as
well as horiz size. Adjusting R10 for more over scan might
remove the phase
error. Of course the horizontal sync bar will disappear, but
be sure the
TV image center is centered.
This symptom can be divided into two cases. One is accompanied with too much noise or snow, the other is not (simply weak
in contrast).
Cause: Weak contrast and snowy picture are caused by a trouble in the antenna or in the RF amplifier circuit.
Plain weak contrast is caused by a trouble between the mixer and the video amplifier circuit inclusive.
Check whether the TV set has a weak contrast reception in all channels. If you observe weak contrast in only one station, check
the faulty contact in the tuner. If there is weak contrast in all channels, adjust the AGC control (both RF and AGC) first. If the
symptom cannot be eliminated, check if the symptom is accompanied with snow or not. If the picture is snowy, check for an
open circuit in the antenna feeder cable or in the RF amplifier circuit. If the picture is not snowy, observe the output signal of
the video detector with an oscilloscope. Normally, a signal of around 1.5 V p-p to 2 V p-p can be observed. If the strength of the
signal is very low, check the mixer, VIF, video detector and the AGC circuits. If the output voltage of the video detector is
normal, check the video amplifier circuit.
This symptom is characterized by a monochrome picture even during color reception.
There are three cases of this symptom. 1) color loss in all channels, 2) color loss in a
particular channel and 3) intermittent color loss.
1 No color in all channels. A trouble in any of the following circuits may cause the symptom: bandpass amplifier, ACC, color
killer, 3.58 MHz oscillator, 3.58 MHz output, burst gate and burst amplifier circuits.
2. No color in some or in a particular channel. This symptom is caused by a
misadjustment in the fine-tuning circuit (shift in the local oscillator frequency) or a loose contact in the channel selector
3 Intermittent color loss. This is caused by a loose contact in the channel selector, mismatch between the antenna and the
receiver or an intermittent operation of the 3.58 MHz oscillator.
a Solid-state circuits
The trouble-shooting procedure for color loss in all channels will be discussed.
Nevertheless, it may serve as reference for trouble-shooting the receiver for the other cases of color loss.
Note that for this symptom, the defective component may be in any of the numerous possible defective circuits. Thus, for an
efficient and prompt trouble-shooting, observe the symptom carefully. The exact method of trouble-shooting a receiver for this
kind of symptom varies with the type of circuit used in the chroma or color circuits. The troubleshooting details that will be
given are for circuits similar to the one given in Fig. 21-2. However, the trouble-shooting flow chart shown in Fig. 21-1 may be
used as reference in trouble-shooting other types of circuits. First, adjust the fine-tuning control with the color intensity set at
maximum and the
color killer set at minimum. If you cannot get the color, trouble-shoot the color circuits.
Short the collector and the emitter of the ACC transistor (Q2) in Fig. 21-2. If the
color appears, the ACC circuit is defective. Otherwise, if you cannot regain the color, disconnect the short across the collector
and the emitter of the ACC transistor and ground the emitter of the second bandpass transistor (Q3). After doing so, adjust the
color killer control. If you cannot get the color, the trouble may be in the bandpass amplifier circuit. Otherwise, if you recover a
normal color, the color killer circuit is defective. But if the brighter parts of the picture have a weak tint of blush green, the 3.58
MHz oscillator or the 3.58 MHz output circuit may be defective.
This symptom is also usually referred to as faded or insufficient color. It is characterized by a weak maximum color
reproduction. This symptom can be divided into two cases: 1) weak color in all channels and 2) weak color in some stations.
Cause: Weak color in all channels is caused by a breakdown in the ACC circuit or by a bandpass amplifier with a decreased
gain. Weak color in some stations is caused by a poorly tuned fine-tuning circuit, a mismatch between the antenna and the
feeder cable, a defective antenna, a defective feeder cable or an aging tuner.
Set the color control at maximum and then adjust the fine-tuning circuit with the finetuning knob to get maximum color for
every station. If only some stations have weak
color, check the condition and the matching of the antenna and the feeder cable. A mismatch between the antenna and the
feeder cable affects the receiver’s reception and good color reproduction cannot be expected. Otherwise, if all channels have
weak color and the color strength is not uniform, trouble-shoot the ACC and the bandpass amplifier.
A simple method of detecting a mismatch is to wrap the antenna cable just before the antenna terminals of the receiver with
an aluminum foil about 10 cm long. Move the foil slowly away from the antenna terminals and observe its effect on the color
on the screen.
If the color intensity changes as the foil is moved, then a mismatch between the cable and
the antenna is confirmed. This mismatch causes weak color reproduction.
How Cellphone Works?
As a basic Part of a Technician, It is fully advice that he/she must posses a basic knowledge of what technology he or she come up
to.. Before we procced further, please take a simple brief to inhanced your knowlegde about the Field of What we are going to
discuss hereafter.... Now first come first we all ever wonder how does the cellphone works?
Have you ever wondered how a cell phone works? What makes it different from a regular phone? What's inside of it and how do
they created it? What do all those terms like PCS, GSM, CDMA and TDMA mean?
To start with, one of the most interesting things about a cell phone is that it is actually a radio -- an extremely sophisticated radio,
but a radio nonetheless. The telephone was invented by Alexander Graham Bell in 1876, and wireless communication can trace its
roots to the invention of the radio by Nikolai Tesla in the 1880s (formally presented in 1894 by a young Italian named Guglielmo
Marconi). It was only natural that these two great technologies would eventually be combined.
If you prepare to take a deep knowledge, i recommended you to visit this site and have a brief of Fundamentals of Wireless
A basic technician all need is just to have a simple understanding about cellphones, we do not need extreme and intimate deeper
meaning about it, that's because what we are going to take around here is to fix what those various mobile phones company
created and make it as simple as that... We are going to fix somewhat if their product gets busted by the end user's who
bought it...below is just a simple basic information I gathered to compensate somewhat of what we are going to learn.
Cell Phone Network Technologies:
2G Technology
There are three common technologies used by 2G cell-phone networks for transmitting information:
* Frequency division multiple access (FDMA)
* Time division multiple access (TDMA)
* Code division multiple access (CDMA)
Although these technologies sound very intimidating, you can get a good sense of how they work just by breaking down the title of
each one.
The first word tells you what the access method is. The second word, division, lets you know that it splits calls based on that access
* FDMA puts each call on a separate frequency.
* TDMA assigns each call a certain portion of time on a designated frequency.
* CDMA gives a unique code to each call and spreads it over the available frequencies.
The last part of each name is multiple access. This simply means that more than one user can utilize each cell.
FDMA separates the spectrum into distinct voice channels by splitting it into uniform chunks of bandwidth. To better understand
FDMA, think of radio stations: Each station sends its signal at a different frequency within the available band. FDMA is used mainly
for analog transmission. While it is certainly capable of carrying digital information, FDMA is not considered to be an efficient
method for digital transmission.
In FDMA, each phone uses a different frequency.
TDMA is the access method used by the Electronics Industry Alliance and the Telecommunications Industry Association for Interim
Standard 54 (IS-54) and Interim Standard 136 (IS-136). Using TDMA, a narrow band that is 30 kHz wide and 6.7 milliseconds long is
split time-wise into three time slots.
Narrow band means "channels" in the traditional sense. Each conversation gets the radio for one-third of the time. This is possible
because voice data that has been converted to digital information is compressed so that it takes up significantly less transmission
space. Therefore, TDMA has three times the capacity of an analog system using the same number of channels. TDMA systems
operate in either the 800-MHz (IS-54) or 1900-MHz (IS-136) frequency bands.
TDMA splits a frequency into time slots.
Unlocking Your GSM Phone
Any GSM phone can work with any SIM card, but some service providers "lock" the phone so that it will only work with their service.
If your phone is locked, you can't use it with any other service provider, whether locally or overseas. You can unlock the phone using
a special code -- but it's unlikely your service provider will give it to you. There are Web sites that will give you the unlock code, some
for a small fee, some for free.
TDMA is also used as the access technology for Global System for Mobile communications (GSM). However, GSM implements
TDMA in a somewhat different and incompatible way from IS-136. Think of GSM and IS-136 as two different operating systems that
work on the same processor, like Windows and Linux both working on an Intel Pentium III. GSM systems use encryption to make
phone calls more secure. GSM operates in the 900-MHz and 1800-MHz bands in Europe and Asia and in the 850-MHz and 1900-MHz
(sometimes referred to as 1.9-GHz) band in the United States. It is used in digital cellular and PCS-based systems. GSM is also the
basis for Integrated Digital Enhanced Network (IDEN), a popular system introduced by Motorola and used by Nextel.
GSM is the international standard in Europe, Australia and much of Asia and Africa. In covered areas, cell-phone users can buy one
phone that will work anywhere where the standard is supported. To connect to the specific service providers in these different
countries, GSM users simply switch subscriber identification module (SIM) cards. SIM cards are small removable disks that slip in and
out of GSM cell phones. They store all the connection data and identification numbers you need to access a particular wireless
service provider.
Unfortunately, the 850MHz/1900-MHz GSM phones used in the United States are not compatible with the international system. If
you live in the United States and need to have cell-phone access when you're overseas, you can either buy a tri-band or quad-band
GSM phone and use it both at home and when traveling or just buy a GSM 900MHz/1800MHz cell phone for traveling. You can get
900MHz/1800MHz GSM phones from Planet Omni, an online electronics firm based in California. They offer a wide selection of
Nokia, Motorola and Ericsson GSM phones. They don't sell international SIM cards, however. You can pick up prepaid SIM cards for a
wide range of countries at
CDMA takes an entirely different approach from TDMA. CDMA, after digitizing data, spreads it out over the entire available
bandwidth. Multiple calls are overlaid on each other on the channel, with each assigned a unique sequence code. CDMA is a form of
spread spectrum, which simply means that data is sent in small pieces over a number of the discrete frequencies available for use at
any time in the specified range.
In CDMA, each phone's data has a unique code. All of the users transmit in the same wide-band chunk of spectrum. Each user's
signal is spread over the entire bandwidth by a unique spreading code. At the receiver, that same unique code is used to recover the
signal. Because CDMA systems need to put an accurate time-stamp on each piece of a signal, it references the GPS system for this
information. Between eight and 10 separate calls can be carried in the same channel space as one analog AMPS call. CDMA
technology is the basis for Interim Standard 95 (IS-95) and operates in both the 800-MHz and 1900-MHz frequency bands.
Ideally, TDMA and CDMA are transparent to each other. In practice, high-power CDMA signals raise the noise floor for TDMA
receivers, and high-power TDMA signals can cause overloading and jamming of CDMA receivers.
2G is a cell phone network protocol. Click here to learn about network protocols for Smartphones.
Now let's look at the distinction between multiple-band and multiple-mode technologies.
Multi-band vs. Multi-mode Cell Phones
Dual Band vs. Dual Mode
If you travel a lot, you will probably want to look for phones that offer multiple bands, multiple modes or both. Let's take a look at
each of these options:
* Multiple band - A phone that has multiple-band capability can switch frequencies. For example, a dual-band TDMA phone could
use TDMA services in either an 800-MHz or a 1900-MHz system. A quad-band GSM phone could use GSM service in the 850-MHz,
900-MHz, 1800-MHz or 1900-MHz band.
* Multiple mode - In cell phones, "mode" refers to the type of transmission technology used. So, a phone that supported AMPS
and TDMA could switch back and forth as needed. It's important that one of the modes is AMPS -- this gives you analog service if you
are in an area that doesn't have digital support.
* Multiple band/Multiple mode - The best of both worlds allows you to switch between frequency bands and transmission modes
as needed.
Cellular vs. PCS
Personal Communications Services (PCS) is a wireless phone service very similar to cellular phone service, but with an emphasis on
personal service and extended mobility. The term "PCS" is often used in place of "digital cellular," but true PCS means that other
services like paging, caller ID and e-mail are bundled into the service.
While cellular was originally created for use in cars, PCS was designed from the ground up for greater user mobility. PCS has smaller
cells and therefore requires a larger number of antennas to cover a geographic area. PCS phones use frequencies between 1.85 and
1.99 GHz (1850 MHz to 1990 MHz).
Technically, cellular systems in the United States operate in the 824-MHz to 894-MHz frequency bands; PCS operates in the 1850MHz to 1990-MHz bands. And while it is based on TDMA, PCS has 200-kHz channel spacing and eight time slots instead of the typical
30-kHz channel spacing and three time slots found in digital cellular.
Changing bands or modes is done automatically by phones that support these options. Usually the phone will have a default option
set, such as 1900-MHz TDMA, and will try to connect at that frequency with that technology first. If it supports dual bands, it will
switch to 800 MHz if it cannot connect at 1900 MHz. And if the phone supports more than one mode, it will try the digital mode(s)
first, then switch to analog.
You can find both dual-mode and tri-mode phones. The term "tri-mode" can be deceptive. It may mean that the phone supports two
digital technologies, such as CDMA and TDMA, as well as analog. In that case, it is a true tri-mode phone. But it can also mean that it
supports one digital technology in two bands and also offers analog support. A popular version of the tri-mode type of phone for
people who do a lot of international traveling has GSM service in the 900-MHz band for Europe and Asia and the 1900-MHz band for
the United States, in addition to the analog service. Technically, this is a dual-mode phone, and one of those modes (GSM) supports
two bands.
3G and 3GS Technology
In the next section, we'll take a look at 3G mobile-phone technology.
3G technology is the latest in mobile communications. 3G stands for "third generation" -- this makes analog cellular technology
generation one and digital/PCS generation two. 3G technology is intended for the true multimedia cell phone -- typically called
smartphones -- and features increased bandwidth and transfer rates to accommodate Web-based applications and phone-based
audio and video files.
3G comprises several cellular access technologies. The three most common ones as of 2005 are:
* CDMA2000 - based on 2G Code Division Multiple Access (see Cellular Access Technologies)
* WCDMA (UMTS) - Wideband Code Division Multiple Access
* TD-SCDMA - Time-division Synchronous Code-division Multiple Access
3G networks have potential transfer speeds of up to 3 Mbps (about 15 seconds to download a 3-minute MP3 song). For comparison,
the fastest 2G phones can achieve up to 144Kbps (about 8 minutes to download a 3-minute song). 3G's high data rates are ideal for
downloading information from the Internet and sending and receiving large, multimedia files. 3G phones are like mini-laptops and
can accommodate broadband applications like video conferencing, receiving streaming video from the Web, sending and receiving
faxes and instantly downloading e-mail messages with attachments.
3GS feels wonderfully familiar – it’s design is almost identical to the 3G, and it’s not until you switch the device on that you start to
appreciate the differences. The “S” stands for speed – Apple has used a faster processor in the 3GS, and the impact is immediate,
with applications loading more briskly, programs running noticeably faster, and the already slick user-interface getting an extra layer
of go-faster stripes. It’s also HSDPA compatible, a step up from 3G, meaning it can surf the web at faster speeds. Battery life is longer
too; I was able to squeeze a full day out of my iPhone without needing to give it a lunchtime charging boost.
Learning with Block Diagram on How basically Cell-phone works?
How basically Cell-phone works?
In this lesson we are going to take a brief familiarization of a typical block diagram of a cellphone. Block Diagram can help us
understand the flow of a certain part of a cellphone's circuit. A Cell-phone handset is basically composed of two sections, which is RF
and Baseband Sections.
RF refers to radio frequency, the mode of communication for wireless technologies of all kinds, including cordless phones, radar,
ham radio, GPS, and radio and television broadcasts. RF technology is so much a part of our lives we scarcely notice it for its
ubiquity. From baby monitors to cell phones, Bluetooth® to remote control toys, RF waves are all around us. RF waves are
electromagnetic waves which propagate at the speed of light, or 186,000 miles per second (300,000 km/s). The frequencies of RF
waves, however, are slower than those of visible light, making RF waves invisible to the human eye.
In signal processing, baseband describes signals and systems whose range of frequencies is measured from zero to a maximum
bandwidth or highest signal frequency. It is sometimes used as a noun for a band of frequencies starting at zero.
In telecommunications, it is the frequency range occupied by a message signal prior to modulation.
It can be considered as a synonym to low-pass.
Baseband is also sometimes used as a general term for part of the physical components of a wireless communications product.
Typically, it includes the control circuitry (microprocessor), the power supply, and amplifiers.
A baseband processor is an IC that is mainly used in a mobile phone to process communication functions.
Basically Baseband also composed of to sections which is the Analog and Digital Processing Sections. So, we are going to separate
each other for better and easier to understand.
Cell-phone have three different sections which is the following.
I prepare this to be simple and easy instead of using or explaining it with deep technical terms .
In this manner, it is easy for us to understand the concepts and methods of how basically the cellphone works.
Cell-phone have three sections since baseband is differentiated by into two which is the Analog and Digital function while the RF
section remains as a whole circuit section.. which is the following cosists.
1. Radio Frequency (RF Section)
2. The Analog Baseband Processor
3. And the Digital Baseband Processor.
Radio Frequency Processing Section
The RF section is the part of the cell-phone circuit is also known as RF Transceiver.
It is the section that transmit and receive certain frequency to a network and synchronize to other phone.
The RF - A radio section is based on two main Circuits.
1. Transmitter
2 . Reciever
A simple mobile phone uses these two circuits to correspond to an other mobile phone. A Transmitter is a circuit or device which is
used to transmit radio signals in the air.and a reciever is simply like radios which are used to recieve transmissions(Radiation) which
is spread in the air by any transmitter on a specific frequency.
The two way communication is made possible by setting two transmitters and two recievers sycronized in this form that a trasmitter
in a cell phone is syncronised with the frequency of other cell phone's recieving frequency same like the transmitter of second cell
phone is syncronised with the recieving frequency of first cell phone. So first cell phone transmits its radiation in the air while the
other phone listens it and same process is present in the opposit side. so these hand held two cell phones correspond to one
the technology used in these days is a little bit different but it is based on the basic theory prescribed before. the today's technology
will be discussed in later on.
Things we should know about Nokia
Nokia is the largest manufacturer of mobile (cellphone) company in world. Its total market share is
around 38% . Its a Finland based company with its branches all over the world. Nokia produces GSM, CDMA,
and W-CDMA (UMTS) mobile devices. It also offers Internet services for its mobile users, which include music,
maps, media, messaging and games. Nokia is also the fifth most valuable global brand in the
Interbrand/BusinessWeek Best Global Brands list of 2008. It is ranked 85 in terms of revenue in fortune 500
some of the things we should know about Nokia.
The name of Nokia originates from Nokia town of Finland which is named after river Nokianvirta which flows
through the town.
Nokia has been listed as the 20th most admirable company in the world by Fortune’s list of 2006 (1st in network
communications, 4th non-US company).
If we reverse the name of Nokia it becomes “aikon” which is used in many SDK software packages, including
Nokia’s own Symbian S60 SDK.
Nokia phones do not start its call timers until the call is actually initiated( Except for Series 60 based handsets
like the Nokia 6600 ) which is unlike most of the today’s handsets.
Nokia’s mobile phone User’s Guides mostly uses the Agfa Rotis Sans font which is Nokia’s corporate font and
was originally designed by Eric Spiekermann.
The sms tunes available to users of Nokia phones are actually Morse code. “Special” tone in Morse code for
“SMS”, “Ascending” tone is Morse code for “Connecting People”(Nokia’s slogan) and the “Standard” tone is
Morse code for “M” (Message).
Nokia is currently the world’s largest digital camera manufacturer because the sales of its camera-equipped
mobile phones have exceeded those of any conventional camera manufacturer.
The world’s first commercial GSM call was made in 1991 in Helsinki over a Nokia-supplied network, by Prime
Minister of Finland Harri Holkeri, using a Nokia phone.
The ringtone “Nokia tune” is actually based on a 19th century guitar work named “Gran Vals” by Spanish
musician Francisco Tárrega. The Nokia Tune was originally named “Grande Valse” on Nokia phones but later was
changed to “Nokia Tune” around 1998 when it became so well known that people referred to it as the “Nokia
Understanding about nokia.....
What is DCT-3, DCTL, DCT-4, DCT-4+, WD2 and BB5 Nokia Phones?
As of now , all popular nokia units are divided into 6 category: DCT3, DCTL,
DCT4, DCT4+, WD2, BB5...
DCT3- common only are 3210 5110 6110 6150 3310 3350 3410 3390 8210 8250
8290 2100 3610 etc.
image of 3310 take a closely look the code or name of part like CCNT stands for power ic,
COBBA ( audio ic) and HAGAR (RF IC)
DCT4- common only are 8310 6610 7210 3100 3510 3530 1100 2600 etc..
image of 3100 see the difference between dct3 and dct4.. dct4 has no
name cobba, ccnt & hagar..but now it have UEM and Mjolner.. cobba & ccnt
merge as UEM, flash & ram make as one and Mjolner replaced hagar.. see it?
DCT4+ common only are 1110 1200 6070 3220 7260 7360 etc..i
image of 7360 same
as dct4... all ic are same
name exept the size...
all ic part are smaller
than dct4, but its all the
same name and
WD2- common only are 6600 7650 3650 3230 n-gage 6260 etc..
image of 6600 same also as dct4.. it has same ic but wd2 has now 4 flash ic
parts and the Ram has now separated and of course the LCD has now wide
BB5 common only are n-series like n70 n73 6680 6630 etc.
image of N70 so now bb5 has fusion all the category. It now
combined all parts; small and big, but the UEM is now same as
CPU size and many other parts are added.
Samsung Service Codes for different models of Samsung
mobile phones
For all:
*#06# Show IMEI
*#9999# Show mobile Software Version
*#0837# Show mobile Software Version (instructions)
*#0001# Show Serial Parameters
*#9125# Activates the smiley when charging
*#0523# LCD Contrast
*#9998*228# Battery status (capacity, voltage,
*#9998*246# Program status
*#9998*289# Change Alarm Buzzer Frequency
*#9998*324# Debug Screens
*#9998*364# Watchdog
*#9998*377# EEPROM Error Stack - Use side keys to select
*#9998*427# Trace Watchdog
*#9998*523# Change LCD contrast
*#9998*544# Jig detect
*#9998*636# Memory status
*#9998*746# SIM File Size
*#9998*778# SIM Service Table
*#9998*785# RTK (Run Time Kernel) errors - if ok then phn
is reset, info is put in memory error
*#9998*786# Run, Last UP, Last DOWN
*#9998*837# Mobile Software Version
*#9998*842# Test Vibrator - Flash the screenlight during 10
sec and vibration activated
*#9998*862# Vocoder Reg - Normal, Earphone or Carkit
*#9998*872# Diag
*#9998*947# Reset On Fatal Error
*#9998*999# Last/Chk
*#9998*9266# Yann debug screen (Debug Screens?)
*#9998*9999# Software version
*0001*s*f*t# Changes serial parameters (s=?, f=0.1, t=0.1)
*0002*?# unknown Samsung's comand
*0003*?# unknown Samsung's comand
For Samsung SGH (R210, T100, A300...)
if Samsung code is in format *#9998*xxx#
try write in this *#0xxx#
For Samsung SGH-600 SGH-2100
*2767*3855# Full EEPROM Reset (THIS CODE REMOVES SPLOCK! but also changes IMEI to 447967-89-400044-0
*2767*2878# Custom EEPROM Reset
For Samsung E700
*2767*688# remove USER CODE and SIMLOCK
For Samsung V200
Power on the mobile phone without SIM card and type these
*2767*63342# and press green button
*2767*3855# and press green button
*2767*2878# and press green button
*2767*927# and press green button
*2767*7822573738# press button
Phone will be unlocked, but all trims are resetted !!!
phone battery must be fully charged
For Samsung S500
*2767*MVT# (*2767*688#) E2P MVT Reset
*#SIMLOCK# (*#7465625#)
China Mobile Phones Service Codes
default user code: 1122, 3344, 1234, 5678
Engineer mode: *#110*01#
Factory mode: *#987#
Enable COM port: *#110*01# -> Device -> Set UART -> PS
Config -> UART1/115200
Restore factory settings: *#987*99#
LCD contrast: *#369#
software version: *#800#
software version: *#900#
set default language: *#0000# Send
set English language: *#0044# Send
set English language (new firmware): *#001# Send
Service codes BenQ:
software version: *#300#
test mode: *#302*20040615#
Service codes Pantech:
software version: *01763*79837#
service menu: *01763*476#
reset defaults (phone/user code reset to default):
Service codes 3xx, 5xx:
software version: *#79#
software version: *#837#
Service codes VK200, VK2000, VK2010, VK2020, VK4000:
software version: *#79#
service menu: *#9998*8336# (hold #)
reset defaults (phone/user code reset to default):
*#9998*7328# (hold #)
LG Service codes: software version: 2945#*#
Sony-Ericsson Service codes: J100 software version: #82#
Fly Service codes:
2040(i) reset defaults: *#987*99# Send
MX200 reset defaults: *#987*99# Send
MX200 software version: *#900# Send
SL300m reset defaults: *#987*99# Send
SL300m software version: *#900# Send
SL500m reset defaults: *#987*99# Send
SL500m software version: *#900# Send
MP500 reset defaults: *#987*99# Send
MP500 software version: *#900# Send
Set language to English: *#0044#
Set language to Russian: *#0007#
Service codes Konka:
C926 software version: *320# Send
C926 set default language: *#0000# Send
C926 set English language: *#0044# Send
Service codes GStar:
GM208 (Chinese Nokea 6230+) engineering menu: *#66*#
Set language to English: *#0044#
Set language to Russian: *#0007#
Service codes Motorola:
Motofone F3 software version: **9999* Send
C113, C114, C115, C115i, C116, C117, C118 software version:
C138, C139, C140 software version: #02#*
C155, C156, C157 software version: #02#*
C257, C261 software version: #02#*
V171, V172, V173 software version: #02#*
V175, V176, V176 software version: #02#*
C168, W220 software version: *#**837#
W208, W375 software version: #02#*
ZTE Mobile1- *938*737381#
unlocking phone code,only press***847# without simcard
E900 software version: *#5002*8376263#
E900 full reset: *2767*3855#
Service codes Spice:
S404 enable COM port: *#42253646633# -> Device -> Set
UART -> PS -> UART1/115200
S410 engineer mode: *#3646633#
S900 software version: *#8375#
S900 serial no: *#33778#
Service codes Philips:
S200 enable COM port: *#3338913# -> Device -> Set UART ->
PS -> UART1/115200
Service codes “Chinese” models:
default user code: 1122, 3344, 1234, 5678
Engineer mode: *#110*01#
Factory mode: *#987#
Enable COM port: *#110*01# -> Device -> Set UART -> PS
Config -> UART1/115200
Restore factory settings: *#987*99#
LCD contrast: *#369#
software version: *#800#
software version: *#900#
Service codes BenQ:
software version: *#300#
test mode: *#302*20040615#
Service codes Pantech:
software version: *01763*79837#
service menu: *01763*476#
reset defaults (phone/user code reset to default):
Service codes VK-Mobile 3xx, 5xx:
software version: *#79#
software version: *#837#
service menu: *#85*364# (hold #)
Service codes VK200, VK2000, VK2010, VK2020, VK4000:
software version: *#79#
service menu: *#9998*8336# (hold #)
reset defaults (phone/user code reset to default):
*#9998*7328# (hold #)
Service codes LG:
software version: 2945#*#
KG300 NVRAM format: 2945#*# -> menu 15
Service codes Sony-Ericsson:
J100 software version: #82#
Service codes Fly:
M100 software version: ####0000#
2040(i) reset defaults: *#987*99# Send
MX200 reset defaults: *#987*99# Send
MX200 software version: *#900# Send
SL300m reset defaults: *#987*99# Send
SL300m software version: *#900# Send
SL500m reset defaults: *#987*99# Send
SL500m software version: *#900# Send
MP500 reset defaults: *#987*99# Send
MP500 software version: *#900# Send
Set language to English: *#0044#
Set language to Russian: *#0007#
Service codes Konka:
C926 software version: *320# Send
C926 set default language: *#0000# Send
C926 set English language: *#0044# Send
Service codes GStar:
GM208 (Chinese Nokea 6230+) engineering menu: *#66*#
Set language to English: *#0044#
Set language to Russian: *#0007#
Service codes Motofone-F3:
Motofone F3 software version: **9999* Send
***300* Set SIM Pin
***310* / ***311* SIM Pin ON | OFF
***000* Reset Factory settings
***644* Set Voicemail number
***260* / ***261* Auto keypad lock ON | OFF
***510* / ***511* Voice Prompts ON | OFF
***160* / ***161* Restricted Calling (Phonebook only) ON |
***200608* Send: software version
***200606* Send: software version
***200806* Send: flex version
***250* / ***251* Keypad tones ON | OFF
***470* Select time format
***500* /***501* Prepaid Balance Display ON | OFF
***520* Change language
Service codes Motorola:
C113, C114, C115, C115i, C116, C117, C118 software version:
C138, C139, C140 software version: #02#*
C155, C156, C157 software version: #02#*
C257, C261 software version: #02#*
V171, V172, V173 software version: #02#*
V175, V176, V176 software version: #02#*
C168, W220 software version: *#**837#
W208, W375 software version: #02#*
and “yes””
Enter into Engineering Mode: *#110*01#
Enter into factory Mode: *#987#
Restore Factory Settings: *#987*99#
Check Software Version: *#900# OR *#800#
Default User Codes: 1122, 3344, 1234, 5678
Change LCD Contrast: *#369#
To Enable COM Port: *#110*01# -> Device -> Set UART -> PS
Config -> UART1/115200
Codes to Change Screen Language:
 *#0000# + Send : Set Default Language
 *#0007# + Send : Set Language to Russian
 *#0033# + Send : Set Language to French
 *#0034# + Send : Set Language to Spanish
 *#0039# + Send : Set Language to Italian
 *#0044# + Send : Set Language to English
 *#0049# + Send : Set Language to German
*#0066# + Send : Set Language to Thai
*#0084# + Send : Set Language to Vietnamese
*#0966# + Send : Set Language to Arabic
ALL LG mobile phones Service codes for Security lock reset
service tests/software version check.
ALL LG service codes.
ALL LG 2G : 2945#*#
LG U8110 277634#*#
LG U8120 277634#*#
LG U8120 v105 47328545454#
LG U8130 47328545454#
LG U8138 47328545454#
LG U8180 v10A 49857465454#
LG U8180 v11A 492662464663#
LG U8330 637664#*#
LG U8360 *6*41*12##
LG U8360 V.10D & V.10E *5*33*62##
LG U8380 525252#*#
LG U8550 885508428679#*#
LG 8550 (italian Unlock Flash)v08j 2945#*#
LG U880 U890 142358#*#
LG U900 v09e 277634#*#
LG U900 v10b 082065#*#
LG U310 566366#*#
LG U310 menù NCK815118#*#
LG L600V 63342425#*#
If you use a desktop computer, you might already know that there isn't any single part called the "computer." A computer is really a
system of many parts working together. The physical parts, which you can see and touch, are collectively called hardware. (Software,
on the other hand, refers to the instructions, or programs, that tell the hardware what to do.)
The illustration below shows the most common hardware in a desktop computer system. Your system may look a little different, but
it probably has most of these parts. A laptop computer has similar parts but combines them into a single notebook-sized package.
Desktop computer system
Let's take a look at each of these parts.
System unit
The system unit is the core of a computer system. Usually it's a rectangular box placed on or underneath your desk. Inside this box
are many electronic components that process information. The most important of these components is the central processing unit
(CPU), or microprocessor, which acts as the "brain" of your computer. Another component is random access memory (RAM), which
temporarily stores information that the CPU uses while the computer is on. The information stored in RAM is erased when the
computer is turned off.
Almost every other part of your computer connects to the system unit using cables. The cables plug into specific ports (openings),
typically on the back of the system unit. Hardware that is not part of the system unit is sometimes called a peripheral device or
System unit
Your computer has one or more disk drives—devices that store information on a metal or plastic disk. The disk preserves the
information even when your computer is turned off.
Hard disk drive
Your computer's hard disk drive stores information on a hard disk, a rigid platter or stack of platters with a magnetic surface.
Because hard disks can hold massive amounts of information, they usually serve as your computer's primary means of storage,
holding almost all of your programs and files. The hard disk drive is normally located inside the system unit.
Hard disk drive
CD and DVD drives
Nearly all computers today come equipped with a CD or DVD drive, usually located on the front of the system unit. CD drives use
lasers to read (retrieve) data from a CD, and many CD drives can also write (record) data onto CDs. If you have a recordable disk
drive, you can store copies of your files on blank CDs. You can also use a CD drive to play music CDs on your computer.
DVD drives can do everything that CD drives can, plus read DVDs. If you have a DVD drive, you can watch movies on your computer.
Many DVD drives can record data onto blank DVDs.
If you have a recordable CD or DVD drive, periodically back up (copy) your important files to CDs or DVDs. That way, if your
hard disk ever fails, you won't lose your data.
Floppy disk drive
Floppy disk drives store information on floppy disks, also called floppies or diskettes. Compared to CDs and DVDs, floppy disks can
store only a small amount of data. They also retrieve information more slowly and are more prone to damage. For these reasons,
floppy disk drives are less popular than they used to be, although some computers still include them.
Floppy disk
Why are floppy disks "floppy"? Even though the outside is made of hard plastic, that's just the sleeve. The disk inside is made of a
thin, flexible vinyl material.
A mouse is a small device used to point to and select items on your computer screen. Although mice come in many shapes, the
typical mouse does look a bit like an actual mouse. It's small, oblong, and connected to the system unit by a long wire that resembles
a tail. Some newer mice are wireless.
A mouse usually has two buttons: a primary button (usually the left button) and a secondary button. Many mice also have a wheel
between the two buttons, which allows you to scroll smoothly through screens of information.
When you move the mouse with your hand, a pointer on your screen moves in the same direction. (The pointer's appearance might
change depending on where it's positioned on your screen.) When you want to select an item, you point to the item and then click
(press and release) the primary button. Pointing and clicking with your mouse is the main way to interact with your computer.
A keyboard is used mainly for typing text into your computer. Like the keyboard on a typewriter, it has keys for letters and numbers,
but it also has special keys:
The function keys, found on the top row, perform different functions depending on where they are used.
The numeric keypad, located on the right side of most keyboards, allows you to enter numbers quickly.
The navigation keys, such as the arrow keys, allow you to move your position within a document or webpage.
You can also use your keyboard to perform many of the same tasks you can perform with a mouse.
A monitor displays information in visual form, using text and graphics. The portion of the monitor that displays the information is
called the screen. Like a television screen, a computer screen can show still or moving pictures.
There are two basic types of monitors: CRT (cathode ray tube) monitors and LCD (liquid crystal display) monitors. Both types
produce sharp images, but LCD monitors have the advantage of being much thinner and lighter. CRT monitors, however, are
generally more affordable.
LCD monitor (left); CRT monitor (right)
A printer transfers data from a computer onto paper. You don't need a printer to use your computer, but having one allows you to
print e-mail, cards, invitations, announcements, and other materials. Many people also like being able to print their own photos at
The two main types of printers are inkjet printers and laser printers. Inkjet printers are the most popular printers for the home. They
can print in black and white or in full color and can produce high-quality photographs when used with special paper. Laser printers
are faster and generally better able to handle heavy use.
Inkjet printer (left); laser printer (right)
Speakers are used to play sound. They may be built into the system unit or connected with cables. Speakers allow you to listen to
music and hear sound effects from your computer.
Computer speakers
To connect your computer to the Internet, you need a modem. A modem is a device that sends and receives computer information
over a telephone line or high-speed cable. Modems are sometimes built into the system unit, but higher-speed modems are usually
separate components.
Cable modem
A computer case (also known as a computer chassis, cabinet, box, tower, enclosure, housing, system unit or simply case) is the
enclosure that contains most of the components of a computer (usually excluding the display, keyboard and mouse). A computer
case is sometimes incorrectly referred to metonymously as a CPU referring to a component housed within the case. CPU was a
common term in the earlier days of home computers, when peripherals other than the motherboard were usually housed in their
own separate cases.
Power supply
Inside a custom-built computer: the power supply at the bottom has its own cooling fan.
A power supply unit (PSU) converts alternating current (AC) electric power to low-voltage DC power for the internal components of
the computer. Some power supplies have a switch to change between 230 V and 115 V. Other models have automatic sensors that
switch input voltage automatically, or are able to accept any voltage between those limits. Power supply units used in computers are
nearly always switch mode power supplies (SMPS). The SMPS provides regulated direct current power at the several voltages
required by the motherboard and accessories such as disk drives and cooling fans.
The motherboard is the main component inside the case. It is a large rectangular board with integrated circuitry that connects the
other parts of the computer including the CPU, the RAM, the disk drives (CD, DVD, hard disk, or any others) as well as any
peripherals connected via the ports or the expansion slots.
Components directly attached to the motherboard include:
The CPU (Central Processing Unit) performs most of the calculations which enable a computer to function, and is
sometimes referred to as the "brain" of the computer. It is usually cooled by a heat sink and fan. Most newer CPUs include
an on-die Graphics Processing Unit (GPU).
The Chipset, which includes the north bridge, mediates communication between the CPU and the other components of the
system, including main memory.
The Random-Access Memory (RAM) stores the code and data that are being actively accessed by the CPU.
The Read-Only Memory (ROM) stores the BIOS that runs when the computer is powered on or otherwise begins execution,
a process known as Bootstrapping, or "booting" or "booting up". The BIOS (Basic Input Output System) includes boot
firmware and power management firmware. Newer motherboards use Unified Extensible Firmware Interface (UEFI) instead
of BIOS.
Buses connect the CPU to various internal components and to expansion cards for graphics and sound.
o Current
 PCI Express: for expansion cards such as graphics, sound, network interfaces, TV tuners, etc.
 PCI: for other expansion cards.
 SATA: for disk drives.
o Obsolete
 AGP: superseded by PCI Express.
 VLB: VESA Local Bus, superseded by AGP.
 Micro Channel architecture
 ISA: expansion card slot format obsolete in PCs, but still used in industrial computers.
Ports for external peripherals. These ports may be controlled directly by the south bridge I/O controller or provided by
expansion cards attached to the motherboard.
o Memory Card
Expansion cards
The expansion card (also expansion board, adapter card or accessory card) in computing is a printed circuit board that can be
inserted into an expansion slot of a computer motherboard or backplane to add functionality to a computer system via the
expansion bus.
An example of an expansion card is a sound card that enables the computer to output sound to audio devices, as well as accept
input from a microphone. Most modern computers have hardware support for sound integrated in the motherboard chipset but
some users prefer to install a separate sound card as an upgrade. Most sound cards, either built-in or added, have surround sound
capabilities and 3-D sound effects.
Secondary storage devices
Computer data storage, often called storage or memory, refers to computer components and recording media that retain digital
data. Data storage is a core function and fundamental component of computers.
Fixed media
Hard disk drives: a hard disk drive (HDD; also hard drive, hard disk, or disk drive)[2] is a device for storing and retrieving
digital information, primarily computer data. It consists of one or more rigid (hence "hard") rapidly rotating discs (often
referred to as platters), coated with magnetic material and with magnetic heads arranged to write data to the surfaces and
read it from them.
Solid-state drives: a solid-state drive (SSD), sometimes called a solid-state disk or electronic disk, is a data storage device
that uses solid-state memory to store persistent data with the intention of providing access in the same manner of a
traditional block I/O hard disk drive. SSDs are distinguished from traditional magnetic disks such as hard disk drives (HDDs)
or floppy disk, which are electromechanical devices containing spinning disks and movable read/write heads.
RAID array controller - a device to manage several internal or external hard disks and optionally some peripherals in order
to achieve performance or reliability improvement in what is called a RAID array.
Removable media
Optical Disc Drives for reading from and writing to various kinds of optical media, including Compact Discs such as CDROMs, DVDs, DVD-RAMs and Blu-ray Discs. Optical discs are the most common way of transferring digital video, and are
popular for data storage as well.
Floppy disk drives for reading and writing to floppy disks, an outdated storage media consisting of a thin disk of a flexible
magnetic storage medium. These were once standard on most computers but are no longer in common use. Floppies are
used today mainly for loading device drivers not included with an operating system release (for example, RAID drivers).
Zip drives, an outdated medium-capacity removable disk storage system, for reading from and writing to Zip disks, was first
introduced by Iomega in 1994.
USB flash drive plug into a USB port and do not require a separate drive. USB flash drive is a typically small, lightweight,
removable, and rewritable flash memory data storage device integrated with a USB interface. Capacities vary, from
hundreds of megabytes (in the same range as CDs) to tens of gigabytes (surpassing Blu-ray discs but also costing
significantly more).
Memory card readers for reading from and writing to Memory cards, a flash memory data storage device used to store
digital information. Memory cards are typically used on mobile devices. They are thinner, smaller and lighter than USB flash
drives. Common types of memory cards are SD and MS.
Tape drives read and write data on a magnetic tape, and are used for long term storage and backups.
Input and output peripherals
Input and output devices are typically housed externally to the main computer chassis. The following are either standard or very
common to many computer systems.
Wheel mouse
Input devices allow the user to enter information into the system, or control its operation. Very early computer systems had literal
toggle switches that could be tested by running programs as a simple form of user input; modern personal computers have
alphanumeric keyboards and pointing devices to allow the user to interact with running software.
Text input devices
o Keyboard - a device to input text and characters by depressing buttons (referred to as keys or buttons).
Pointing devices
o Mouse - a pointing device that detects two dimensional motion relative to its supporting surface.
 Optical Mouse - uses light (laser technology) to determine mouse motion.
o Trackball - a pointing device consisting of an exposed protruding ball housed in a socket that detects rotation
about two axes.
o Touchscreen - senses the user pressing directly on the monitor.
Gaming devices
o Joystick - a hand-operated pivoted stick whose position is transmitted to the computer.
o Game pad - a hand held game controller that relies on the digits (especially thumbs) to provide input.
o Game controller - a specific type of controller specialized for certain gaming purposes.
Image, Video input devices
o Image scanner - a device that provides input by analyzing images, printed text, handwriting, or an object.
o Web cam - a video camera used to provide visual input that can be easily transferred over the internet.
Audio input devices
o Microphone - an acoustic sensor that provides input by converting sound into electrical signals.
Output devices display information in a human readable form. A program-controlled pilot lamp would be a very simple example of
an output devices. Modern personal computers have full-screen point-addressable graphic displays and often a printing device to
produce paper copies of documents and images.
Printer - a device that produces a permanent human-readable text or graphic document.
o Laser printer
o Inkjet printer
o Dot matrix printer
o Thermal printer
Computer monitors
Definition of Abbreviations on Mobile Phones Circuit
2G 2nd Generation
3G 3rd Generation
3Gs 3rd Generation speed
4G 4th Generation
A/D-converter Analog-to-digital converter
ACI Accessory Control Interface
ADC Analog-to-digital converter
ADSP Application DPS (expected to run high level tasks)
AGC Automatic gain control (maintains volume)
ALS Ambient light sensor
AMSL After Market Service Leader
ARM Advanced RISC Machines
ARPU Average revenue per user (per month or per year)
ASIC Application Specific Integrated Circuit
ASIP Application Specific Interface Protector
B2B Board to board, connector between PWB and UI board
BB Baseband
BC02 Bluetooth module made by CSR
BIQUAD Bi-quadratic ,type of filter function)
BSI Battery Size Indicator
BT Bluetooth
CBus MCU controlled serial bus connected to
UPP_WD2,UEME and Zocus
CCP Compact Camera Port
CDSP Cellular DSP (expected to run at low levels)
CLDC Connected limited device configuration
CMOS Complimentary metal-oxide semiconductor circuit (low
power consumption)
COF Chip on Foil
COG Chip on Glass
CPU Central Processing Unit
CSR cambridge silicon radio
CSTN Color Super Twisted Nematic
CTSI Clock Timing Sleep and interrupt block of Tiku
CW Continuous wave
D/A-converter Digital-to-analouge converter
DAC Digital-to-analouge converter
DBI Digital Battery Interface
DBus DSP controlled serial bus connected between UPP_WD2
and Helgo
DCT-4 Digital Core Technology
DMA Direct memory access
DP Data Package
DPLL Digital Phase Locked Loop
DSP Digital Signal Processor
DtoS Differential to Single ended
EDGE Enhanced data rates for global/GSM evaluation
EGSM Extended GSM
EM Energy management
EMC Electromagnetic compability
EMI Electromagnetic interference
ESD Electrostatic discharge
FCI Functional cover interface
FPS Flash Programming Tool
FR Full rate
FSTN Film compensated super twisted nematic
GND Ground, conductive mass
GPIB General-purpose interface bus
GPRS General Packet Radio Service
GSM Group Special Mobile/Global System for Mobile
HF Hands free
HFCM Handsfree Common
HS Handset
HSCSD High speed circuit switched data (data transmission
connection faster than GSM)
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