- 13.01.2018
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по специальности:
1309000 «Оптическое и электронное оборудование»
Астана 2017 г/
Оглавление
ABOUT COMMUNICATION SYSTEM IN KAZAKHSTAN
DEVELOPMENT OF RADIO TECHNOLOGIES
GLOSSARY OF ELECTRONIC TERMS AND ABBREVIATIONS
DEVELOPMENT OF TELECOMMUNICATION
TELEPHONE CONVERSATION. BAD CONNECTION.
DIFFERENCE BETWEEN VOLTAGE AND CURRENT
The transport and communıcatıons system of Kazakhstan ınherıted after the break up of the Sovıet Unıon ıs ın a complex state. At the time of the Sovıet Unıon our transport was not independent. It as under the control of different ministries located in Moscow.At that time all communıcatıons went through Moscow. Now Kazakhstan is an independent country and it is obvious that its transport system has many drawbacks.
In the past Kazakhstan and Central Asia had communıcatıon links with no one but Russia. There were eleven railway and sixty motor way routes to the Russia and no routes leading beyond the ”Iron curtain”.The only railway station Druzhba on the Chinese border was not in operation for political reasons.Not a single air flight linked Kazakhstan with the outer world. There were no broadcasts from abroad to say nothing in the Internet access.Now the situation changed rapidly. The gates to China are openedwith thr railways and motor roads.
At present with the reconstruction of Aktay sea port there appeared a water route to Iran.A pilot project on passinger and freight railway communıcatıons with Istanbul via Tashkent and Teheran is under way. Kazakhstan participates in the implementation of TRASECA project aimed at eatablishing transport corridors from Europe to the Pacific zone via the Caucasus, Central Asia, Kazakhstan and China. Pipelines transport Kazakhstan’s oil to the world markets.Air routes link the two capitals practically with all neighboring countries. The World Web access is becoming an every day practice with more and more Kazakhstanians.
Vocabulary note
an instrument инструмент
sends and receives принимать и получать
voice messages голосовые сообщения
by means of electric current использовать электросеть
one of most valuable means один из важных значении в
of communications коммуникации
far sound далекий звук
telephone can send information телефон может отправлять информацию
from one computer to another с одного компьютера в другое
artificial satellites искусственные спутники
are installed or carried установить
connect with связан с
Telephone is an instrument that sends and receives voice messages, usually by means of electric current. It is one of most valuable means of communications. In just a few second, you can telephone person across the street, in another part of the country, or on another continent. The word telephone comes from two Greek words meaning far and sound.
In its most basic form, a telephone enable people to talk with one another at distances beyond the range of the human voice messages, but also written words, drawings, photographs and even video images, in addition telephone can send information from one computer to another.
Telephone in people’s homes are just one part of a vast, complex telephone network also includes large computers, tremendous length of cooper wire and hair thin strands of glass, cables buried in the ground and laid along the oceans, radio transmitters and receivers and artificial satellites orbiting far above the earth by means of wires that run through the houses and buildings. A small clip connects each telephone to the wiring. Other phones are installed or carried in bag or packet. Such phones connect with the network by radio.
Alexander Graham Bell invented the telephone in 1876. Today hundreds of millions of telephones serve people all over the world.
Complete as in the text.
Telephone is an instrument that …
It is one of most valuable means …
The word telephone comes from two Greek …
In its most basic form, a telephone enable people to talk …
Telephone in people’s homes are just one part of a vast, complex telephone network also includes
Answer the questions:
What is telephone?
Is it one of most valuable means of communications?
Where does the word telephone come from?
How can person talk with one another?
What does complex telephone network include?
Who and when invented the telephone?
What is telephone for you?
Does the mobile telephone play great role in your life? Why?
On the 14 February in
1876 American of the Scottish origin Alexander Bell gave in Bureau of patents
of the USA a request on the vehicle that he named a telephone to them. By only
two hours later similar order was placed a by other American on the last name
Gray. In England Bell with success continued demonstrations collecting plenty
of public. Finally, “delightful telephone presentation” was given to the queen
and her family. The supporters of Bell, taking credits, created in reply “New
England telephone of company” and plunged into a fight. By the result of fight,
however, creation became at the end of 1879 incorporated “Bell of company”.
Bell placing New York to Chicago telephone call in 1892. Credit for the invention of the electric telephone frequently disputed, and new controversie, over the issue have arisen from time to time. As with other inventions such as radio, television, the light bulb and the computer, there were several inventors who did experimental work on voice transmission over a wire and improved on each other ideas. Antonio Meucci, Johann Philipp Reis, Elisha Gray, Alexander Graham Bell, and Thomas Edison among others, have all been credited with pioneering work on the telephone.
An undisputed fact is that Alexander Graham Bell was the first to be awarded a patent for the electric telephone by the United States Patent and Trademark Office in March 1876. That first patent by Bell was the master patent of the telephone, from which other patents telephone devices and features flowed.
By the rainy morning of Augusts, 4, 1922 in the USA and Canada on a minute all telephones were off. America buried Alexander Graham Bell. The 13 million telephones sets of various kinds and constructions in honor a great inventor.
Types of telephone
dial telephone, rotary dialing telephone; набирать номер
pushbutton telephone, touch-tone telephone кнопочный телефон;
pay phone, public phone; телефон-автомат;
mobile phone, cell phone / cellular phone; мобильный телефон;
cordless / wireless phone, radiotelephone; радиотелефон;
satellite phone; спутниковый телефон;
IP telephone, softphone (software phone); телефон через копьютер;
WiFi phone (Wireless Fidelity). безпроводной телефон
2.Telephone parts and accessories
the base unit / the base; база
the receiver / the handset; трубка
the microphone; микрофон;
the dial; the buttons; диск; кнопка;
the redial button; кнопка повтора;
the hold button; кнопка удержания;
the bell; the hook; звонок; рычаг;
the telephone plug; телефон штекеры;
the telephone jack; розетка телефона;
the headset; earphone, earphones; наушник, наушник;
answering machine; fax machine; modem; автоответчик; факс; модем;
speakerphone; громкоговоритель;
Who gave a demonstration (1895) of the wireless telegraph?
Marconi succeeded in sending the letter S across the Atlantic Ocean using Morse code, isn’t it?
Radio is based on the studies of James Clerk Maxwell, who developed the mathematical theory of electromagnetic waves, and Heinrich Hertz, who devised an apparatus for generating and detecting them. Guglielmo Marconi, recognizing the possibility of using these waves for a wireless communication system, gave a demonstration (1895) of the wireless telegraph, using Hertz's spark coil as a transmitter and Edouard Branly's coherer (a radio detector in which the conductance between two conductors is improved by the passage of a high-frequency current) as the first radio receiver. The effective operating distance of this system increased as the equipment was improved, and in 1901, Marconi succeeded in sending the letter S across the Atlantic Ocean using Morse code. In 1904, Sir John A. Fleming developed the first vacuum electron tube , which was able to detect radio waves electronically. Two years later, Lee de Forest invented the audion, a type of triode, or three-element tube, which not only detected radio waves but also amplified them.
Radio telephony—the transmission of music and speech—also began in 1906 with the work of Reginald Fessiden and Ernst F. W. Alexanderson, but it was not until Edwin H. Armstrong patented (1913) the circuit for the regenerative receiver that long-range radio reception became practicable. The major developments in radio initially were for ship-to-shore communications. Radios that combine transmitters and receivers are now widely used for communications. Police and military forces and various businesses commonly use such radios to maintain contact with dispersed individuals or groups. Citizens band (CB) radios, two-way radios operating at frequencies near 27 megahertz, most typically used in vehicles for communication while traveling, became popular in the 1970s. Cellular telephones, despite the name, are another popular form of radio used for communication.
A radio communication system send signals by radio. –
Types of radio communication systems deployed depend on technology, standards, regulations, radio spectrum allocation, user requirements, service positioning, and investment.
The radio equipment involved in communication systems includes a transmitter and a receiver, each having an antenna and appropriate terminal equipment such as a microphone at the transmitter and a loudspeaker at the recieiver in the case of a voice-communication system.
May 7 is celebrated in our country as Radio’s Day, in commemoration of the discovery made by the Russian scientist Alexander Popov. On this day in 1895, Popov gave a working demonstration of the first radio receiver in the world, and several months later he transmitted the first radio message over a distance of 250 metres.
We know Soviet television to have developed swiftly in the past years and televiewing to have become one of the favourite pastimes of our people.
In 1961 Soviet television appeared on the international screen. More than 100 million people in 14 countrioes of Europe were able to enjoy Soviet TV programmes. In their turn Soviet people saw programmes from London ; Paris; Warsaw; Prague and other European cities.
Radio-engineering, electronics and television are finding increasing application in the national economy, transport and medicine.
The automation of industrial processes, of heat and power stations,remote control and management, the development of electronic computers and cybernetic systems—all this is possible because of the achievements of electronics.A television system at the Magnitogorsk Iron and Steel Mills helps to regulate the charging of the furnaces, the vacuum pouring of steel and other operations TV at sea and river ports makes possible the remote control and management of loading. With underwater television it is possible to check on the submerged part of a ship’s hull, to inspect sunkenships, and to study the sea and river bottom at varving depths, the conditionof sluices, while with television sets of special design it is possible to supervise the operation of bore holes and oil wells.
We know the organization of radio communication with the first Soviet cosmonauts to have been a triumph of Soviet radio-engineering. Now that the flights of the first cosmonauts are over, we know the radio electronic equipment to have operated faultlessly. This was the first two-way radio contact between man in outer space and the Earth.
During the space flights television enabled doctors on the Earth to follow the state of health of the cosmonauts, their movements and actions.
The development of Soviet science and technology in the field of space research sets more complicated tasks to be carried out by our radio-engineering and electronics experts.
One of the practical tasks of radio-engineering in outer space is to use artificial satellites for the needs of man on Earth. They ensure the transmission of meterological data collected by instruments carried by artificial satellites. The sputniks are also for international radio communication, broadcasting and world-wide television systems.
Answer the following questions:
1.Why was May 7 marked in our country as Radio Day?
2. When did Soviet television appear on the international screen?
3. How is electronics applied in the national economy?
4 How could doctors on the Earth follow the state of health of the cosmonaut during his flight?
5. How did the radio electronic equipment operate during the flights of the Soviet cosmonauts?
6. What device makes remote control possible?
7. What practical tasks are carried out by our radio-engineering and electronics experts?
RADIO TRANSMITTERSA "transmitter" is an electronic device which, usually with the aid of an antenna, propagates an electromagnetic signal such as radio, television, or other telecommunications.
Principles of radio
One of many applications of electricity is the generation of invisible waves of energy called radio waves.
With Oersted's accidental discovery of electromagnetism, it was realized that electricity and magnetism were related to each other. When an electric current was passed through a conductor, a magnetic field was generated perpendicular to the axis of flow. Likewise, if a conductor was exposed to a change in magnetic flux perpendicular to the conductor, a voltage was produced along the length of that conductor. So far, scientists knew that electricity and magnetism always seemed to affect each other at right angles.
Scottish physicist James Clerk Maxwell (1831-1879) "unified" the study of electricity and magnetism in four relatively tidy equations. He discovered that electric and magnetic fields were related to one another, with or without the presence of a conductive path for electrons to flow. Maxwell's discovery was this:
A changing electric field produces a perpendicular magnetic field, and A changing magnetic field produces a perpendicular electric field.
All of this can take place in open space, the alternating electric and magnetic fields supporting each other as they travel through space at the speed of light. This dynamic structure of electric and magnetic fields propagating through space is better known as an electromagnetic wave.
There are many kinds of natural radiative energy composed of electromagnetic waves. Even light is electromagnetic in nature. So are X-rays and "gamma" ray radiation. The only difference between these kinds of electromagnetic radiation is the frequency of their oscillation (alternation of the electric and magnetic fields back and forth in polarity). Byk using a source of AC voltage and a special device called an antenna, we can create electromagnetic waves (of a much lower frequency than that of light) with ease.
An antenna is nothing more than a device built to produce a dispersing electric or magnetic field. Two fundamental types of antennae are the dipole and the loop.
The dipole looks like an open circuit, and the loop like a short circuit. These pieces of wire are effective radiators of electromagnetic fields when connected to AC sources of high frequency. The two open wires of the dipole act as a sort of capacitor (two conductors separated by a dielectric), with the electric field open to dispersal instead of being concentrated between two closely-spaced plates. The closed wire path of the loop antenna acts like an inductor with a large air core, again providing opportunity for the field to disperse away from the antenna instead of being concentrated and contained as in a normal inductor.
As the powered dipole radiates its changing electric field into space, a changing magnetic field is produced at right angles, thus sustaining the electric field further into space, and so on as the wave propagates at the speed of light. As the powered loop antenna radiates its changing magnetic field into space, a changing electric field is produced at right angles, with the same end-result of a continuous electromagnetic wave sent away from the antenna. Both types antennas achieves the same basic task: the controlled production of an electromagnetic field.
When attached to a source of high-frequency AC power, an antenna acts as a transmitting device, converting AC voltage and current into electromagnetic wave energy.
A "radio receiver" is an electronic circuit that receives its input from an antenna, uses electronic filters to separate a wanted radio signal from all other signals picked up by this antenna, amplifies it to a level suitable for further processing, and finally converts through demodulation and decoding the signal into a form usable for the consumer, such as sound, pictures, digital data, measurement values, navigational positions, etc. [http://www.radio-electronics.com/info/receivers/index.php Radio-Electronics, "Radio Receiver Technology"]
The crystal radio receiver is a very simple kind of radio receiver. It needs no battery or power source except the power received from radio waves by a long outdoor wire antenna.
Portable radios include simple transistor radios that are typically monoaural and receive the AM, FM, and/or short wave broadcast bands. FM, and often AM, radios are sometimes included as a feature of portable CD, MP3 CD, and USB key players, as well as cassette player/recorders.
Self-powered portable radios, such as clockwork radios are used in developing nations or as part of an emergency preparedness kit. [http://radio.electrical-guide.info/types/ The Radio Guide, "Types of Portable Radios"]
A communications receiver is a type of radio receiver used as a component of radio communication link. Commercial communications receivers are characterised by high stability and reliability of performance, and are generally adapted for remote control and monitoring.
A - Abbreviation for "ampere" a unit of electrical current.
absorption - Loss or dissipation of energy as it travels through a medium, Example: radio waves lose some of their energy as they travel through the atmosphere.
AC - Abbreviation for "Alternating Current"
acceptor atoms - Trivalent atoms that accept free electrons from pentavalent atoms.
AC coupling - Circuit that passes an AC signal while blocking a DC voltage.
AC/DC - Equipment that will operate on either an AC or DC power source.
AC generator - Device used to transform mechanical energy into AC electrical power.
AC load line - A graph representing all possible combinations of AC output voltage and current for an amplifier.
AC power supply - Power supply that delivers an AC voltage.
active component - A component that changes the amplitude of a signal between input and output.
active filter - A filter that uses an amplifier in addition to reactive components to pass or reject selected frequencies.
active region - The region of BJT operation between saturation and cutoff used for linear amplification.
AC voltage - A voltage in which the polarity alternates.
ADC - Abbreviation for "analog to digital converter"
Admittance - (symbol "Y") Measure of how easily AC will flow through a circuit. Admittance is the reciprocal of impedance and is measured in siemens.
AF - Abbreviation for "audio frequency".
AFC - Abbreviation for "automatic frequency control".
AGC - Abbreviation for "automatic gain control"
alkaline cell - A primary cell that delivers more current than a carbon-zinc cell. Also known as an "alkaline manganese cell".
alligator clip - Spring clip on the end of a test lead used to make a temporary connection.
alpha - Ratio of collector current to emitter current in a bipolar junction transistor (BJT). Greek letter alpha "" is the symbol used.
alternating current - An electric current that rises to a maximum in one direction, falls back to zero and then rises to a maximum in the opposite direction and then repeats.
alternator - Name for an AC generator.
AM - Abbreviation for "amplitude modulation"
ammeter - A meter used to measure current.
ampere - Unit of electrical current.
amplifier - A circuit that increases the voltage, current, or power of a signal.
amplitude - Magnitude or size of a signal voltage or current.
analog - Information represented as continuously varying voltage or current rather than in discrete levels as opposed to digital data varying between two discrete levels.
anode - The positive electrode or terminal of a device. The "P" material of a diode.
antenna, transmitting - A device that converts an electrical wave into an electromagnetic wave that radiates away from the antenna.
antenna, receiving - A device that converts a radiated electromagnetic wave into an electrical wave.
apparent power - Power attained in an AC circuit as a product of effective voltage and current which reach their peak at different times.
arc - Discharge of electricity through a gas such as lightning discharging through the atmosphere.
armature - The rotating or moving component of a magnetic circuit.
armstrong oscillator - An oscillator that uses an isolation transformer to achieve positive feedback from output to input.
astable multivibrator - An oscillator that produces a square wave output from a DC voltage.
atom - The smallest particle that an element can be broken down into and still maintain its unique identity.
atomic number - The number of positive charges or protons in the nucleus of an atom.
attenuate - To reduce the amplitude of an action or signal. The opposite of amplification.
audio - Relating to frequencies that can be heard by the human ear. Approximately 20 Hz. to 20 kHz.
autotransformer - A single winding transformer where the output is taken from taps on the winding.
average value - A value of voltage or current where the area of the wave above the value equals the area of the wave below the value.
AVC - Abbreviation for "automatic volume control"
avionics - Aviation electronics.
AWG - Abbreviation for "American wire gauge". A gauge that assigns a number value to the diameter of a wire.
balanced bridge - Condition that occurs when a bridge circuit is adjusted to produce a zero output.
band-pass filter - A tuned circuit designed to pass a band of frequencies between a lower cut-off frequency (f1) and a higher cut-off frequency (f2). Frequencies above and below the pass band are heavily attenuated.
band-stop filter - A tuned circuit designed to stop frequencies between a lower cut-off frequency (f1) and a higher cut-off frequency (f2) of the amplifier while passing all other frequencies.
bandwidth - Width of the band of frequencies between the half power points.
barrier potential - The natural difference of potential that exists across a forward biased pn junction.
base - The region that lies between the emitter and collector of a bipolar junction transistor (BJT).
base biasing - A method of biasing a BJT in which the bias voltage is supplied to the base by means of a resistor.
battery - A DC voltage source containing two or more cells that convert chemical energy to electrical energy.
baud - A unit of signaling speed equal to the number of signal events per second. Not necessarily the same as bits per second.
beta - (b) The ratio of collector current to base current in a bipolar junction transistor (BJT).
bias - A DC voltage applied to a device to control its operation.
binary - A number system having only two symbols, 0 and 1. A base 2 number system.
bipolar junction transistor - (BJT), A three terminal device in which emitter to collector current is controlled by base current.
bistable multivibrator - A multivibrator with two stable states. An external signal is required to change the output from one state to the other. Also called a latch.
bleeder current - A current drawn continuously from a source. Bleeder current is used to stabilize the output voltage of a source.
bode plot - A graph of gain versus frequency.
branch current - The portion of total current flowing in one path of a parallel circuit.
breakdown voltage - Voltage at which the breakdown of a dielectric or insulator occurs.
break over voltage - Minimum voltage required to cause a diac to break down and conduct.
bridge rectifier - A circuit using four diodes to provide full wave rectification. Converts an AC voltage to a pulsating DC voltage.
buffer - An amplifier used to isolate a load from a source.
bulk resistance - The natural resistance of a "P" type or "N" type semiconductor material.
Butterworth filter - A type of active filter characterized by a constant gain (flat response) across the mid-band of the circuit and a 20 dB per decade roll-off rate for each pole contained in the circuit.
BW - Abbreviation for bandwidth.
bypass capacitor - A capacitor used to provide an AC ground at some point in a circuit.
byte - Group of eight binary digits or bits.
cable - Group of two or more insulated wires.
CAD - Abbreviation for "computer aided design"
calibration - To adjust the correct value of a reading by comparison to a standard.
capacitance - The ability of a capacitor to store an electrical charge. The basic unit of capacitance is the Farad.
capacitive reactance - The opposition to current flow provided by a capacitor. Capacitive reactance is measured in ohms and varies inversely with frequency.
capacitor - An electronic component having capacitive reactance.
capacitor microphone - Microphone whose operation depends on variations in capacitance caused by varying air pressure on the movable plate of a capacitor.
carbon-film resistor - Device made by depositing a thin carbon film on a ceramic form.
carbon microphone - Microphone whose operation depends on pressure variation in carbon granules causing a change in resistance.
carbon resistor - Resistor of fixed value made by mixing carbon granules with a binder which is moulded and then baked.
cascaded amplifier - An amplifier with two or more stages arranged in a series configuration.
cascode amplifier - A high frequency amplifier made up of a common-source amplifier with a common-gate amplifier in its drain network.
cathode - The negative terminal electrode of a device. The "N" material in a junction diode.
cathode ray tube - (CRT) Vacuum tube used to display data in a visual form. Picture tube of a television or computer terminal.
cell - Single unit used to convert chemical energy into a DC electrical voltage.
center frequency - Frequency to which an amplifier is tuned. The frequency half way between the cut-off frequencies of a tuned circuit.
center tap - Midway connection between the two ends of a winding.
center tapped rectifier - Circuit that make use of a center tapped transformer and two diodes to provide full wave rectification.
center tapped transformer - A transformer with a connection at the electrical center of a winding.
ceramic capacitor - Capacitor in which the dielectric is ceramic.
charge - Quantity of electrical energy.
charge current - Current that flows to charge a capacitor or battery when voltage is applied.
chassis - Metal box or frame into which components are mounted.
chassis ground - Connection to a chassis.
chebyshev filter - A type of active filter characterized by high roll-off rates (40 dB per decade per pole) and mid-band gain that is not constant.
choke - Inductor used to oppose the flow of alternating current.
circuit - Interconnection of components to provide an electrical path between two or more components.
circuit breaker - A protective device used to open a circuit when current exceeds a maximum value. In effect a reusable fuse.
clamper - A diode circuit used to change the DC level of a waveform without distorting the waveform.
clapp oscillator - A variation of the Colpitts oscillator. An added capacitor is used to eliminate the effects of stray capacitance on the operation of the basic Colpitts oscillator.
class A amplifier - A linear amplifier biased so the active device conducts through 360 degrees of the input waveform.
class B amplifier - An amplifier with two active devices. The active components are biased so that each conducts for approximately 180 degrees of the input waveform cycle.
class C amplifier - An amplifier in which the active device conducts for less than 180 degrees of the input waveform cycle.
clipper - A diode circuit used to eliminate part of a waveform
clipping - Distortion caused by overdriving an amplifier.
clock - A square waveform used for synchronizing and timing of several circuits.
closed circuit - Circuit having a complete path for current flow.
closed-loop gain - Gain of an amplifier when a feedback path is present.
coaxial cable - Transmission line in which the signal carrying conductor is covered by a dialectric and another conductor.
coefficient of coupling - The degree of coupling between two circuits.
coercive force - (H) Magnetizing force needed to reduce residual magnetism in a material to zero.
collector - The semiconductor region in a bipolar junction transistor through which a flow of charge carriers leaves the base region.
collector characteristic curve - A graph of collector voltage over collector current for a given base current.
color code - Set of colors used to indicate value of a component.
colpitts oscillator - An oscillator with a pair of tapped capacitors in the feedback network.
common-anode display - A multi-segment light emitting diode (LED) with a single positive voltage input connection. Separate cathode connections are provided for each individual segment.
common cathode display - A multi-segment light emitting diode (LED) with a single negative voltage input connection. Separate anode connections are provided for each individual segment.
common base amplifier - A BJT circuit in which the base connection is common to both input and output.
common collector amplifier - A BJT circuit in which the collector connection is common to both input and output.
common drain amplifier - A FET circuit in which the drain connection is common to both input and output.
common emitter amplifier - A BJT circuit in which the emitter connection is common to both input and output.
common gate amplifier - A FET circuit in which the gate connection is common to both input and output.
common source amplifier - A FET circuit in which the source connection is common to both input and output.
common-mode rejection ratio - (CMRR) The ratio of op-amp differential gain to common-mode gain. A measure of an op-amp's ability to reject common-mode signals such as noise.
common-mode signals - Signals that appear simultaneously at two inputs of an operational amplifier (op-amp). Common mode signals are always equal in amplitude and phase.
comparator - An op-amp circuit that compares two inputs and provides a DC output indicating the polarity relationship between the inputs.
complementary symmetry amplifier - A class B amplifier using matched complementary transistors. Does not require a phase inverter for push-pull output.
complementary transistors - Two transistors, one NPN and one PNP having near identical characteristics. N-channel and P-channel FETs can also be complementary.
complex numbers - Numbers composed of a real number part and an imaginary number part.
compliance - The maximum possible peak-to-peak output of an amplifier.
constant current circuit - Circuit used to maintain constant current to a load having resistance that changes.
contact - Current carrying part of a switch, relay or connector.
continuity - Occurs when a complete path for current exists.
conventional current flow - Concept of current produced by the movement of positive charges towards the negative terminal of a source.
copper loss - Power lost in transformers, generators, connecting wires and other parts of a circuit due to current flow through the resistance of copper conductors.
core - Magnetic material within a coil used to concentrate the magnetic field.
coulomb - Unit of electric charge. A negative coulomb charge consists of 6.24 × 1018 electrons.
counter electromotive force - (counter emf) Voltage induced into an inductor due to an alternating or pulsating current. Counter emf is always in polarity opposite to that of the applied voltage. Opposing a change of current.
coupling - To electronically connect two circuits so that signal will pass from one to the other.
covalent bond - The way some atoms complete their valence shells by sharing valence electrons with neighbouring atoms.
crossover distortion - Distortion caused by both devices in a class B amplifier being cut-off at the same time.
crowbar - Circuit used to protect the output of a source from a short circuited load. Load current is limited to a value the source can deliver without damage.
CRT - Abbreviation for cathode ray tube.
crystal - Natural or synthetic piezoelectric or semiconductor material with atoms arranged with some degree of geometric regularity.
crystal-controlled oscillator - Oscillator that uses a quartz crystal in its feedback path to maintain a stable output frequency.
current - Measured in amperes, it is the flow of electrons through a conductor. Also know as electron flow.
current amplifier - Amplifier to increase signal current.
current divider - Parallel network designed to divide the total current of a circuit
current feedback - Feedback configuration where a portion of the output current is fed back to the amplifier input.
current-limiting resistor - Resistor in the path of current flow to control the amount of current drawn by a device.
current mirror - Term used to describe the fact that DC current through the base circuit of a class B amplifier is approximately equal to the DC collector current.
cutoff - Condition when an active device is biased such that output current is near zero or beyond zero.
cutoff frequency - Frequency at which the power gain of an amplifier falls below 50% of maximum.
cycle - When a repeating wave rises from zero to a positive maximum then back to zero and on to a negative maximum and back to zero it is said to have completed one cycle.
DAC - Abbreviation for "digital to analog converter."
damping - Reduction in magnitude of oscillation due to energy being dissipated as heat.
Darlington pair - An amplifier consisting of two bipolar junction transistors with their collectors connected together and the emitter of one connected to the base of the other. Circuit has an extremely high current gain and input impedance.
DC - Abbreviation for "direct current".
DC load line - A graph representing all possible combinations of voltage and current for a given load resistor in an amplifier.
DC offset - The change in input voltage required to produce a zero output voltage when no signal is applied to an amplifier.
DC power supply - Any source of DC power for electrical equipment.
dead short - Short circuit having zero resistance.
decade - A frequency factor of ten.
decibel - (dB) a logarithmic representation of gain or loss.
degenerative feedback - Also called negative feedback. A portion of the output of an amplifier is inverted and connected back to the input. This controls the gain of the amplifier and reduces distortion and noise.
delay time - The time for collector current to reach 10% of its maximum value in a BJT switching circuit.
depletion region - The area surrounding a pn junction that is depleted of carriers.
depletion mode - In a FET, an operating mode where reverse gate-source voltage is used to deplete the channel of free carriers. This reduces the size of the channel and increases its resistance.
depletion-mode MOSFET - A MOSFET designed to operate in either depletion mode or enhancement mode.
device - A component or part.
diac - A two terminal bidirectional thyristor. Has a symmetrical switching mode.
dielectric - Insulating material between two plates where an electrostatic field exists.
dielectric constant - Property of a material that determines how much electrostatic energy can be stored per unit volume when unit voltage is applied.
dielectric strength - The maximum voltage an insulating material can withstand without breaking down.
differential amplifier - An amplifier in which the output is in proportion to the differences between voltages applied to its two inputs.
differentiator - A circuit in which the output voltage is in proportion to the rate of change of the input voltage. A high pass RC circuit.
diffusion - Tendency of conduction band electrons to wander across a pn junction to combine with valence band holes.
digital - Relating to devices or circuits that have outputs of only two discrete levels. Examples: 0 or 1, high or low, on or off, true or false etc.
diode - A two terminal device that conducts in only one direction.
DIP - Abbreviation for "dual in line package."
direct coupling - Where the output of an amplifier is connected directly to the input of another amplifier or to a load. Also known as DC coupling because DC signals are not blocked.
direct current - Current that flows in only one direction.
discharge - Release of energy stored in either a battery or a capacitor.
discrete component - Package containing only a single component as opposed to an integrated circuit containing many components in a single package.
dissipation - Release of electrical energy in the form of heat.
distortion - An undesired change in a waveform or signal.
distributed capacitance - Any capacitance other than that within a capacitor. For example, the capacitance between adjacent turns of wire in a coil.
distributed inductance - Any inductance other than that within an inductor. Example inductance in any conductor.
domain - A moveable magnetized area in a magnetized material. Also known as magnetic domain.
donor atoms - Pentavalent atoms that give up electrons to the conduction band in an N type semiconductor material.
doping - The process of adding impurity atoms to intrinsic (pure) silicon or germanium to improve the conductivity of the semiconductor material.
dot convention - Standard used with transformer symbols to indicate whether the secondary voltage is in phase or out of phase with the primary voltage.
drift - A problem that can develop in tuned amplifiers when the frequency of the tuned circuit changes due to temperature or component aging.
dropping resistor - Resistor whose value has been chosen to drop or develop a given voltage.
dry cell - DC voltage generating chemical cell using a non liquid (paste) electrolyte.
dual in-line package - Integrated circuit package having two rows of connecting pins.
dual trace oscilloscope - Oscilloscope that can simultaneously display two signals.
dynamic - Relating to conditions that are changing or in motion.
E-core - Laminated form in the shape of the letter "E", onto which inductors and transformers are wound.
eddy currents - Currents induced into a conducting core due to the changing magnetic field. Eddy currents produce heat which is a loss of power and lowers the efficiency of an inductor.
efficiency - The amount of power delivered to the load of an amplifier as a percentage of the power required from the power supply.
electric charge - Electric energy stored on the surface of a material. Also known as a static charge.
electric field - A field or force that exists in the space between two different potentials or voltages. Also known as an electrostatic field.
electricity - Science states that certain particles possess a force field or charge. The charge possessed by an electron is negative while the charge possessed by a proton is positive. Electricity can be divided into two groups, static and dynamic. Static electricity deals with charges at rest and dynamic electricity deals with charges in motion.
electric polarization - A displacement of bound charges in a dielectric when placed in an electric field.
electro acoustic transducer - Device that produces an energy transfer from electric to acoustic (sound) or from acoustic to electric. Examples include a microphone, earphones and loudspeakers.
electroluminescence - Conversion of electrical energy into light energy.
electrolyte - Electrically conducting liquid (wet) or paste (dry)
electrolytic capacitor - A capacitor having an electrolyte between the two plates. A thin layer of oxide is deposited on only the positive plate. The oxide acts as the dielectric for the capacitor. Electrolytic capacitors are polarized and so must be connected in correct polarity to prevent breakdown.
electromagnet - A coil of wire usually wound on a soft iron or steel core. When current is passed through the coil a magnetic field is generated. The core provides an easy path for the magnetic lines of force. This concentrates the field in the core.
electromagnetic communication - Use of an electromagnetic wave to pass information between two points. Also called wireless communication.
electromagnetic induction - Voltage produced in a coil due to relative motion between the coil and magnetic lines of force.
electromagnetic spectrum - List or diagram showing the range of electromagnetic radiation.
electromagnetic wave - Wave that consists of both electric and magnetic variation.
electromagnetism -Relates to the magnetic field generated around a conductor when current is passed through it.
electromechanical transducer - Device that transforms electrical energy into mechanical energy (electric motor) or mechanical energy into electrical energy (generator).
electromotive force - (emf) Force that causes the motion of electrons due to potential difference between two points. (voltage)
electron - Smallest sub atomic particle of negative charge that orbits the nucleus of an atom.
electron flow -Electrical current produced by the movement of free electrons towards a positive terminal.
electrostatic - Related to static electric charge.
electrostatic field - Force field produced by static electrical charges.
emitter - The semiconductor region from which charge carriers are injected into the base of a bipolar junction transistor.
emitter feedback - Coupling from the emitter output to the base input of a bipolar junction transistor.
emitter follower - A common collector amplifier. Has a high current gain, high input impedance and low output impedance.
energized - Being electrically connected to a voltage source so the device is activated.
energy - Capacity to do work.
engineering notation - A floating point system in which numbers are expressed as products consisting of a number greater than one multiplied by an appropriate power of ten that is some multiple of three.
enhancement-mode MOSFET - A field effect transistor in which there are no charge carriers in the channel when the gate source voltage is zero.
equivalent resistance - Total resistance of all the individual resistances in a circuit.
fall time - Time it takes the falling edge of a pulse to go from 90% of peak voltage to 10% of peak voltage.
farad - The basic unit of capacitance.
feedback - A portion of the output signal of an amplifier which is connected back to the input of the same amplifier.
feedback amplifier - An amplifier with an external signal path from its output back to its input.
ferrite - A powdered, compressed and sintered magnetic material having high resistively. The high resistance makes eddy current losses low at high frequencies.
ferrite bead - Ferrite composition in the form of a bead. Running a wire through the bead increases the inductance of the wire.
ferrite-core inductor - An inductor wound on a ferrite core.
ferrites - Compound composed of iron oxide, a metallic oxide and ceramic. The metal oxides include zinc, nickel, cobalt or iron.
ferrous - Composed of and or containing iron. A ferrous metal exhibits magnetic characteristics as opposed to non-ferrous material.
fiber optics - Laser's light output carries information that is conveyed between two points by thin glass optical fibers.
field effect transistor - (FET) A voltage controlled transistor in which the source to drain conduction is controlled by gate to source voltage.
filament - Thin thread of carbon or tungsten which produces heat or light with the passage of current.
filter - Network consisting of capacitors, resistors and/or inductors used to pass certain frequencies and block others.
flip flop - A bistable multivibrator. A circuit which has two output states and is switched from one to the other by means of an external signal (trigger).
floating ground - Common connection in a circuit that provides a return path for current but is not connected to an earth ground.
flow soldering - Flow or wave soldering technique in large scale electronic assembly to solder all the connections on a printed circuit board by moving the board over a wave of molten solder.
flux - Material used to remove oxide films from the surface of metals in preparation for soldering.
flux - In magnetism, the magnetic field consisting of lines of force.
flux density - The concentration of magnetic lines of force. Determines strength of the magnetic field.
flywheel effect - Sustaining effect of oscillation in an LC circuit.
forward bias - A PN junction bias which allows current to flow through the junction. Forward bias decreases the resistance of the depletion layer.
free electrons - Electrons that are not in any orbit around a nucleus.
free running multivibrator - A multivibrator that produces a continuous output waveform without any signal input. A square wave generator used to produce a clock signal.
frequency - Rate of recurrence of a periodic wave. Measured in Hertz (cycles per second).
frequency-division multiplex - (FDM) Transmission of two or more signals over a common path by using a different frequency band for each signal.
frequency-domain analysis - A method of representing a waveform by plotting its amplitude against frequency.
frequency meter - Meter used to measure frequency of periodic waves.
frequency multiplier - A harmonic conversion circuit in which the frequency of the output signal is an exact multiple of the input frequency.
frequency response - Indication of how well a circuit responds to different frequencies applied to it.
frequency response curve - A graph of amplitude over frequency indicating a circuit response to different frequencies.
full scale deflection - (FDS) Deflection of a meter's pointer to the farthest position on the scale.
full wave rectifier - Rectifier that makes use of the full AC wave in both the positive and negative half cycles.
function generator - Signal generator that can produce sine, square, triangle and saw tooth output waveforms.
fundamental frequency - Lowest frequency in a complex waveform.
fuse - A protective device in the current path that melts or breaks when current exceeds a predetermined maximum value.
gain - Increase in voltage, current and/or power. Gain is expressed as a ratio of amplifier output value to the corresponding amplifier input value.
gain bandwidth product - A device parameter that indicates the maximum possible product of gain and bandwidth. The gain bandwidth product of a device is equal to the unity gain frequency (funity) of the device.
gamma rays - High frequency electromagnetic radiation from radio active particles.
ganged - Mechanical coupling of two or more capacitors, switches, potentiometers, or any other adjustable components so that adjusting one control will operate all.
gas - Any aeriform or completely elastic fluid which is not a solid or a liquid. Gasses are produced by heating a liquid beyond its boiling point.
geiger counter - Device used to detect nuclear particles.
generator - Device used to convert mechanical energy to electrical energy.
giga - Metric prefix for 1 billion (109).
ground - An intentional or accidental conducting path between an electrical system or circuit and the earth or some conducting body acting in place of the earth. A ground is often used as the common wiring point or reference in a circuit.
gunn diode - A semiconductor diode that utilizes the Gunn effect to produce microwave frequency oscillation or to amplify a microwave frequency signal.
half power point - A frequency at which the power is 50% of maximum. This corresponds to 70.7% of maximum current or voltage.
h-parameters - (hybrid parameters) Transistor specifications that describe the component operating limits under specific circumstances.
half wave rectifier - A diode rectifier that converts AC to pulsating DC by eliminating either the negative or the positive alternation of each input AC cycle.
harmonic - Sine wave that is smaller in amplitude and some multiple of a fundamental frequency. Example: 880 Hz. is the second harmonic of 440 Hz., 880 Hz. is the third harmonic of 220 Hz.
hartley oscillator - An oscillator that uses a tapped inductor in the feedback network.
henry - The basic unit of inductance.
HERTZ - (Hz.) Unit of frequency. One hertz is equal to one cycle per second.
high fidelity - (Hi Fi)Sound reproduction equipment that reproduces sound as near to the original sound as possible
high-pass filter - A tuned circuit designed to pass all frequencies above a desnigated cut-off frequency. Frequencies below the cut-off frequency are rejected or attenuated
high tension - Lethal voltage in the kilovolt range and above.
hole - A gap left in the covalent bond when a valence electron gains sufficient energy to jump to the conduction band
hologram - Three-dimensional picture created with a laser.
holography - The science dealing with three-dimensional optical recording.
horizontally polarized wave - Electromagnetic wave that has the electric field in the horizontal plane.
hybrid circuit - Circuit that combines two technologies (passive and active or discrete and integrated components) onto one microelectronic circuit. Passive components are usual made by thin film techniques, while active components are made with semiconductor techniques.
hysteresis - Amount that the magnetization of a material lags the magnetizing force due to molecular friction. In Schmitt Trigger circuits, the difference between the upper and lower trigger points.
IC - Abbreviation for "integrated circuit"
IC voltage regulator - Three terminal device used to hold the output voltage of a power supply constant over a wide range of load variations.
IGFET - Insulated gate field effect transistor. Another name for a "MOSFET."
impedance - (Z) Measured in ohms it is the total opposition to the flow of current offered by a circuit. Impedance consists of the vector sum of resistance and reactance.
impedance coupling - Coupling of two signal amplifier circuits through the use of an impedance such as a inductor.
impedance matching - Matching the output impedance of a source to the input impedance of a load to attain maximum power transfer.
incandescence - State of a material when heated to the point where it emits light. (red hot or white hot).
induced voltage - Voltage generated in a conductor when subjected to a moving magnetic field.
inductance - Property of a circuit to oppose a change in current. The moving magnetic field produced by a change in current causes an induced voltage to oppose the original change.
inductive circuit - Circuit having greater inductive reactance than capacitive reactance.
inductive reactance - Opposition to the flow of AC current produced by an inductor. Measured in Ohms and varies in direct proportion to frequency.
inductor - Length of conductor used to introduce inductance into a circuit. The conductor is usually wound into a coil to concentrate the magnetic lines of force and maximize the inductance. While any conductor has inductance, in common usage the term inductor usually refers to a coil.
infrared - Electromagnetic heat radiation whose frequencies are above the microwave frequency band and below red in the visible band.
inhibit - To stop an action or block data from passing.
in phase - When two or more waves of the same frequency have their positive and negative peaks occurring at the same time.
input impedance - Opposition to the flow of signal current at the input of a circuit or load.
insulated - When a non conducting material is used to isolate conducting materials from one another.
insulating material - Material that will prevent the flow of current due to its chemical composition.
insulation resistance - Resistance of insulating material. The greater the insulation resistance, the better the insulation.
integrated - When two or more components are combined into a circuit and then incorporated into a single package.
integrator - A device that approximates and whose output is proportional to an integral of the input signal. A low pass filter.
intermediate frequency amplifier - In a super heterodyne radio it amplifies a fixed frequency lower than the received radio frequency and higher than the audio frequency.
intermittent - A fault occurring at random intervals of time. Intermittent problems are often difficult to locate because of the random nature. They often don't occur when the technician is present.
internal resistance - Every source has some resistance in series with the output current. When current is drawn from the source some power is lost due to the voltage drop across the internal resistance. Usually called output impedance or output resistance.
intrinsic material - A semiconductor material with electrical properties essentially characteristic of ideal pure crystal. Essentially silicon or germanium crystal with no measurable impurities.
intrinsic stand-off ratio - A unijunction transistor (UJT) rating used to determine the firing potential of the device.
inverting amplifier - An amplifier that has a 180° phase shift from input to output.
inverting input - In an operational amplifier (op amp) the input that is marked with a minus sign. A signal applied at the inverting input will be given 180° phase shift between input and output.
ion - An atom with fewer electrons in orbit than the number of protons in the nucleus is a positive ion. An atom with a greater number of electrons in orbit than the number of protons in the nucleus is a negative ion.
ionized - Atoms become ionized when they gain or lose a valence electron.
j - A prefix used to indicate an imaginary number. (Operator j)
jack - Socket or connector into which a plug may be inserted.
JFET - Abbreviation for "Junction field effect transistor".
joule - The unit of work and energy.
junction - Contact or connection between two or more wires or cables. The area where the p-type material and n-type material meet in a semiconductor.
junction diode - diode. A semiconductor diode in which the rectifying characteristics occur at a junction between the n-type and p-type semiconductor materials.
kilo - Metric prefix for 1000. (103).
kilovolt-ampere - 1000 volts at 1 ampere.
kilowatt-hour - 1000 watts for 1 hour.
kilowatt-hour meter - A meter used by electric utility companies to measure the amount of electric power used by a customer.
kinetic energy - Energy associated with motion.
Kirchhoff"s current law - The sum of the currents flowing into a point in a circuit is equal to the sum of the currents flowing out of that same point.
Kirchhoff"s voltage law - The algebraic sum of the voltage drops in a closed path circuit is equal to the algebraic sum of the source voltages applied.
knee voltage - The voltage at which a curve joins two relatively straight portions of a characteristic curve. For a PN junction diode, the point in the forward operating region of the characteristic curve where conduction starts to increase rapidly. For a zener diode, the term is often used in reference to the zener voltage rating.
lag - Difference in time between two waveforms of the same frequency expressed in degrees. Example: One waveform lags another waveform by a certain number of degrees.
laminated core - Core made up of sheets of magnetic material insulated from one another by an oxide or varnish.
lamp - Device that produces light.
laser - Device that produces a very narrow intense beam of light. The name is an axcronym for "light amplification by stimulated emission of radiation.
lead - The angle by which one alternating signal leads another in time. Opposite of lag. Also a wire that connects two points in a circuit.
lead-acid cell - Cell made up of lead plates immersed in a sulphuric acid electrolyte. An automobile battery usually consists of six lead-acid cells.
leakage - Small undesirable flow of current through an insulator or dielectric.
LED - Abbreviation for "light emitting diode."
left-hand-rule - If fingers of the left hand are placed around a wire so that the thumb points in the direction of electron flow, the fingers will be pointing in the direction of the magnetic field being produced by the conductor.
Lenz's law - The current induced in a circuit due to a change in the magnetic field is so directed as to oppose the flux, or to exert a mechanical force to oppose the motion.
level detector - An op-amp circuit that compares two inputs and provides a DC output indicating the polarity relationship between the inputs. A comparator.
lie detector - Piece of electronic equipment also called a polygraph used to determine whether a person is telling the truth by looking for dramatic changes in blood pressure, body temperature, breathing rate, heart rate and skin moisture in response to questions.
light - Electromagnetic radiation in a band of frequencies that can be received by the human eye.
lifetime - The time from the creation of an electron hole pair until recombination occurs.
light-emitting diode - A semiconductor diode that converts electric energy into electromagnetic radiation at a visible and near infrared frequencies when its pn junction is forward biased.
limiter - Circuit or device that prevents some portion of its input from reaching the output. A clipper.
linear - Relationship between input and output in which the output varies in direct proportion to the input.
linear scale - A scale in which the divisions are uniformly spaced.
line regulation - The ability of a voltage regulator to maintain a constant voltage when the regulator input voltage varies.
live - Term used to describe a circuit or piece of equipment that is on and has current flow within it.
load - A source drives a load. Whatever component or piece of equipment is connected to a source and draws current from a source is a load on that source.
load current - Current drawn from a source by a load.
load impedance - Vector sum of reactance and resistance in a load.
loading effect - Large load impedance will draw a small load current and so loading of the source is small. (light load). A small load impedance will draw a large load current from the source. (heavy load).
load regulation - The ability of a voltage regulator to maintain a constant output voltage under varying load currents.
load resistance - Resistance of a load.
logic - Science of dealing with the principle and applications of gates, relays and switches.
loss - Term used to describe a decrease in power.
low pass filter - A tuned circuit designed to pass all frequencies below a designated cut-off frequency.
magnet - Body that can be used to attract or repel magnetic materials.
magnetic circuit breaker - Circuit breaker that is tripped or activated by use of an electromagnet.
magnetic coil - Spiral of a conductor which is called an electromagnet.
magnetic core - Material that exists in the center of the magnetic coil to either physically support the windings (non-magnetic material) or to concentrate the magnetic flux (magnetic material).
magnetic field - Magnetic lines of force traveling from the north pole to the south pole of a magnet.
magnetic flux - The magnetic lines of force produced by a magnet.
magnetic leakage - The passage of magnetic flux outside the path along which it can do useful work.
magnetic poles - Points of a magnet from which magnetic lines of force leave (north pole) and arrive (south pole).
magnetism - Property of some materials to attract or repel others.
magnetizing force - Also called magnetic field strength. It is the magneto motive force per unit length at any given point in a magnetic circuit.
magneto motive force - Force that produces a magnetic field.
majority carriers - The conduction band electrons in an n-type material and the valence band holes in a p-type material. Produced by pentavalent impurities in n-type material and trivalent impurities in p-type material.
matched impedance - Condition that occurs when the output impedance of a source is equal to the input impedance of a load.
matching - Connection of two components or circuits so that maximum power is transferred between the two.
maximum power transfer - A theorem that states that maximum power will be transferred from source to load when input impedance of the load equals the output impedance of the source.
Maxwell - Unit of magnetic flux. One maxwell equals one magnetic line of force.
mercury cell - Primary cell using a mercuric oxide cathode, a zinc anode and a potassium hydroxide electrolyte.
metal film resistor - A resistor in which a film of metal oxide or alloy is deposited on an insulating substrate.
metal oxide field effect transistor - (MOSFET) A field effect transistor in which the insulating layer between the gate electrode and the channel is a metal oxide layer.
metal oxide resistor - A metal film resistor in which an oxide of metal (such as tin) is deposited as a film onto the substrate.
meter - Any electrical or electronic measuring device. In the metric system, it is the unit of length equal to 39.37 inches.
meter FSD current - Value of meter current needed to cause the needle to deflect to its maximum position (full scale deflection).
meter resistance - DC resistance of the meter's armature coil.
mica capacitor - Capacitor using mica as the dielectric.
microphone - Electro acoustic transducer that converts sound energy into electric energy.
microwave - Band of very short wavelength radio waves within the UHF, SHF and EHF bands.
mid-band gain - Gain of an amplifier operating within its bandwidth.
mid-point bias - An amplifier biased at the center of its DC load line.
mil - One thousandth of an inch (0.001 in.)
Miller's theorem - A theorem that allows you to represent a feedback capacitor as equivalent input and output shunt capacitors.
minority carriers - The conduction band holes in n-type material and valence band electrons in p-type material. Most minority carriers are produced by temperature rather than by doping with impurities.
mismatch - Term used to describe a difference between the output impedance of a source and the input impedance of a load. A mismatch prevents the maximum transfer of power from source to load.
modulation - Process by which an information signal (audio for example) is used to modify some characteristic of a higher frequency wave known as a carrier (radio for example).
monostable multivibrator - A multivibrator with one stable output state. When triggered, the circuit output will switch to the unstable state for a predetermined period of time and then return to the stable state. A timer.
molecule - Smallest particle of a compound that still retains its characteristics.
MOSFET - Abbreviation for "metal oxide field effect transistor" also known as an "insulated gate field effect transistor). A field effect transistor in which the insulating layer between the gate electrode and the channel is a metal oxide layer.
moving coil microphone - Microphone that uses a moving coil within a fixed magnetic field. Dynamic microphone.
moving coil pick-up - Dynamic phonograph pick-up in which the stylus causes a coil to move within a fixed magnetic field.
moving coil loudspeaker - Loudspeaker that uses a moving "voice coil" placed within a fixed magnetic field. Audio frequency current in the voice coil causes movement which is mechanically transferred to the speaker cone. Also known as a dynamic loudspeaker.
multimeter - Electronic test equipment that can perform multiple tasks. Typically one capable of measuring voltage, current and resistance. More sophisticated modern digital multimeters also measure capacitance, inductance, current gain of transistors and/or anything else that can be measured electronically.
multiplier resistor - Resistor connected in series with a moving coil meter movement to extend the voltage ranges.
multi segmant display - Device made of several light emitting diodes arranged in a numeric or alphanumeric pattern. By lighting selected segments numeric or alphabet characters can be displayed.
multivibrator - A class of circuits designed to produce square waves or pulses. Astable multivibrators produce continuous pulses without an external stimulus or trigger. Monostable multivibrators produce a single pulse for some predetermined period of time only when triggered. Bistable multivibrators produce a DC output which is stable in either one of two states. Either high or low. An external stimulus or trigger is required for the bistable circuit to change states, either high to low or low to high.
mutual inductance - Ability of one inductor's lines of force to link with another inductor.
n-type semiconductor - A semiconductor compound formed by doping an intrinsic semiconductor with a pentavalent element. An n-type material contains an excess of conduction band electrons.
negative - Terminal that has an excess of electrons.
negative charge - A charge that has more electrons than protons
negative feedback - A feedback signal 180° out of phase with an amplifier input signal. Used to increase amplifier stability, bandwidth and input impedance. Also reduces distortion.
negative ground - A system where the negative terminal of the source is connected to the system's metal chassis.
negative ion - An atom having a greater number of electrons in orbit than there are protons in the nucleus.
negative resistance - A resistance such that when the current through it increases the voltage drop across the resistance decreases.
negative temperature coefficient - A term used to describe a component whose resistance or capacitance decreases when temperature increases.
neon bulb - Glass envelope filled with neon gas which when ionized by an applied voltage will glow red.
network - Combination of interconnected components, circuits or systems.
neutral - A terminal, point or object with balanced charges. Neither positive or negative.
neutral atom - An atom in which the number of negative charges (electrons in orbit) is equal to the number of positive charges (protons in the nucleus).
neutral wire - The conductor of a polyphase circuit or a single-phase three wire circuit that is intended to have a ground potential. The potential difference between the neutral and each of the other conductors are approximately equal in magnitude and equally spaced in phase.
neutron - Subatomic particle in the nucleus of an atom and having no electrical charge.
nickel-cadmium cell - A secondary cell that uses a nickel oxide positive electrode and a cadmium negative electrode.
node - Junction or branch point in a circuit.
noise - Unwanted electromagnetic radiation within an electrical or mechanical system.
An operational amplifier circuit having no phase inversion between the input and output.
non-inverting input - The terminal on an operational amplifier that is identified by a plus sign.
non-linear scale - A scale in which the divisions are not equally spaced.
normal closed - Designation which states that the contacts of a switch or relay are closed or connected when at rest. When activated, the contacts open or separated.
normally open - Designation which states that the contacts of a switch or relay are normally open or not connected. When activated the contacts close or become connected.
north pole - Pole of a magnet out of which magnetic lines of force are assumed to originate.
Norton's theorem - Any network of voltage sources and resistors can be replace by a single current source in parallel with a single resistor.
notch filter - A filter which blocks a narrow band of frequencies and passes all frequencies above and below the band.
npn transistor - A bipolar junction transistor in which a p-type base element is sandwiched between an n-type emitter and an n-type collector.
nucleus - Core of an atom. The nucleus contains both positive (protons) and neutral (neutrons) subatomic particles.
octave - Interval between two sounds whose fundamental frequencies differ by a ratio of 2 to 1. 440 Hz. is one octave above 220 Hz.
offset null - An op amp control pin used to eliminate the effects of internal component voltages on the output of the device.
ohm - Unit of resistance symbolized by the Greek capital letter omega (W).
ohmmeter - Device used to measure electrical resistance.
Ohm's law - Relationship between voltage, current and resistance. Ohm's law states that current in a resistance varies in direct proportion to voltage applied and inversely proportional to resistance.
Ohms per volt - Refers to a value of ohms per volt of full scale defection for a moving coil meter movement. The number of ohms per volt is the reciprocal of the amount of current required to produce full scale deflection of the needle. A meter requiring 50 microamps for full scale deflection has an internal resistance of 20 kW per volt. The higher the ohms per volt rating, the more sensitive the meter.
one-shot - Monostable multivibrator.
op-amp - Abbreviation for operational amplifier.
open loop gain - Gain of an amplifier when no feedback is present.
open loop mode - An amplifier circuit having no means of comparing the output with the input. (No feedback.)
operational amplifier - A high gain DC amplifier that has a high input impedance and a low output impedance. Op-amps are the most basic type of linear integrated circuits.
oscillate - To produce a continuous output waveform without an input signal present.
oscillator - An electronic circuit that produces a continuous output waveform with only DC applied.
oscilloscope - An instrument used to display a signal graphically. Shows signal amplitude, period and wave shape in addition to any DC voltage present. A multiple trace oscilloscope can show two or more waveforms at the same time for phase comparison and timing measurements.
out of phase - When the maximum and minimum points of two or more waveshapes do not occur at the same time.
output - Terminal at which a component, circuit or piece of equipment delivers current, voltage or power.
output impedance - Impedance measured across the output terminals of a device without a load connected.
output power - Amount of power a component, circuit or system can deliver to a load.
overload - Condition that occurs when the load is greater than the system was designed to handle. (Load resistance too small, load current too high.) Overload results in waveform distortion and/or overheating.
overload protection - Protective device such as a fuse or circuit breaker that automatically disconnects a load when current exceeds a predetermined value.
paper capacitor - Fixed capacitor using oiled or waxed paper as a dielectric.
parallel - Circuit having two or more paths for current flow. Also called shunt.
parallel resonant circuit - Circuit having an inductor and a capacitor in parallel with one another. Circuit offers a high impedance at resonant frequency. Sometimes called a "tank circuit."
pass band - The range of frequencies that will be passed and amplified by a tuned amplifier. Also the range of frequencies passed by a band pass filter.
passive component - Component that does not amplify a signal. Resistors and capacitors are examples.
passive filter - A filter that contains only passive or non amplifying components.
passive system - System that emits no energy. It only receives. It does not transmit or reveal its position.
peak - Maximum or highest amplitude level.
peak inverse voltage - (PIV) The maximum rated value of a AC voltage acting in the direction opposite to that in which a device is designed to pass current.
peak to peak - Difference between the maximum positive and maximum negative values of an AC waveform.
pentavalent element - Element whose atoms have five valence electrons. Used in doping intrinsic silicon or germanium to produce n-type semiconductor material. Most commonly used pentavalent materials are arsenic and phosphorus.
percent of regulation - The change in output voltage that occurs between no-load and full-load in a DC voltage source. Dividing this change by the full-load value and multiplying the result by 100 gives percent regulation.
percent of ripple - The ratio of the effective rms value of ripple voltage to the average value of the total voltage. Expressed as a percentage.
period - Time to complete one full cycle of a periodic or repeating waveform.
permanence - Magnetic equivalent of magnetic inductance and consequently equal to the reciprocal of reluctance, just as conductance is equal to the reciprocal of resistance.
permanent magnet - Magnet normally made of hardened steel that retains its magnetism indefinitely.
permeability - Measure of how m how much better a material is as a path for magnetic lines of force with respect to air which has a permeability of one. Symbolized by the Greek lower case letter mu (m).
phase - Angular relationship between two waves.
phase angle - Phase difference between two or more waves, normally expressed in degrees.
phase shift - Change in phase of a wave form between two points, expressed as degrees of lead or lag.
phase shift oscillator - An oscillator that uses three RC networks in its feedback path to produce the 180° phase shift required for oscillation.
phase splitter - Circuit that takes a single input signal and produces two output signals that are 180° apart in phase.
phonograph - Piece of equipment used to reproduce sound stored on a disk called a phonograph record.
phosphor - Luminescent material applied to the inner face of a cathode ray tube that when bombarded with electrons will emit light of various colors.<olors.< p=""></olors.<>
photoconductive cell - Material whose resistance decreases or conductance increases when exposed to light.
photoconduction - A process by which the conductance of a material is change by incident electromagnetic radiation in the visible light spectrum.
photo detector - Component used to detect or sense light.
photodiode - A semiconductor diode that changes its electrical characteristics in response to illumination.
photometer - Meter used to measure light intensity.
photon - Discrete portion of electromagnetic energy. A small packet of light.
photoresistor - Also known as a photoconductive cell or light dependent resistor. (LDR) A device whose resistance decreases with exposure to light.
photovoltaic cell - Component commonly called a solar cell used to convert light energy into electrical energy.
pi - Value representing the ratio between the circumference and diameter of a circle and equal to approximately 3.142.
pierce oscillator - A variation of the colpitts oscillator. This oscillator uses a quartz crystal in place of the inductor found in the colpitts oscillator feedback network. The crystal maintains a highly stable output frequency.
piezoelectric crystal - Crystal material that will generate a voltage when mechanical pressure is applied and conversely will undergo mechanical stress when subjected to a voltage.
piezoelectric effect - The production of a voltage between opposite sides of a piezoelectric crystal as a result of pressure or twisting. Also the reverse effect which the application of a voltage to opposite sides causes a deformation to occur at the frequency of the applied voltage. (Converts mechanical energy into electrical energy and electrical energy into mechanical energy.)
pinch-off region - A region on the characteristic curve of a FET in which the gate bias causes the depletion region to extend completely across the channel.
plastic film capacitor - Capacitor in which alternate layers of aluminum foil are separated by thin films of plastic dielectric.
plate - Conductive electrode in either a capacitor or battery. In vacuum tube technology, it is the name given to the anode.
plug - Movable connector that is normally connected into a socket or jack.
pnp transistor - A bipolar junction transistor with an n-type base and p-type emitter and collector.
pole - In an active filter, a single RC circuit. A one pole filter has one capacitor and one resistor. A two pole filter has two RC circuits and so on.
polar coordinates - Either of two numbers that locate a point in a plane by its distance from a fixed point and the angle this line makes with a fixed line.
polarity - Term used to describe positive and negative charges.
polarized - A component which must be connected in correct polarity to function and/or d/or prevent destruction. Example: Electrolytic capacitor.
positive - Polarity of point that attracts electrons as opposed to negative which supplies electrons.
positive charge - A charge that exists in a body that has fewer electrons than protons.
positive feedback - A feedback signal that is in phase with an amplifier input signal. Positive feedback is necessary for oscillation to occur.
positive ground - A system whereby the positive terminal of the source is connected to the system's conducting chassis.
positive ion - Atom that has lost one or more valence electrons resulting in a net positive charge.
potential difference - Voltage difference between two points which will cause current to flow in a closed circuit.
potential energy - Energy that has potential to do work because of its position relative to others.
potentiometer - A variable resistor with three terhree terminals. Mechanical turning of a shaft can be used to produce variable resistance and potential. Example: A volume control is usually a potentiometer.
power - Amount of energy converted by a circuit or component in a unit of time, normally seconds. Measured in units of watts. (joules/second).
power amplifier - An amplifier designed to deliver maximum power output to a load. Example: In an audio system, it is the power amplifier that drives the loudspeaker.
power derating factor - A transistor rating that tells how much the maximum allowable value of PD decreased for each 1°C rise in ambient temperature.
power dissipation - Amount of heat energy generated by a device in one second when current flows through it.
power factor - Ratio of actual power to apparent power.
power loss - Ratio of power absorbed to power delivered.
power supply - Electrical equipment used to deliver either AC or DC voltage.
power supply rejection ratio - A measure of an op-amps ability to maintain a constant output when the supply voltage varies.
primary - First winding of a transformer. Winding that is connected to the source as opposed to secondary which is a winding connected to a load.
primary cell - Cell that produces electrical energy through an internal electrochemical action. Once discharged a primary cell cannot be reused.
printed circuit board - Insulating board containing conductive tracks for circuit connections.
programmable UJT - Unijunction transistor with a variable intrinsic stand-off ratio.
propagation - Traveling of electromagnetic, electrical or sound waves through a medium.
propagation delay - Time required for a signal to pass through a device or circuit.
propagation time - Time required for a wave to travel between two points.
protoboard - Board with provision for attaching components without solder. Also called a breadboard. Primarily used for constructing experimental circuits.
proton - Sub atomic particle within the nucleus of an atom. Has a positive charge.
pulse - Rise and fall of some quantity (usually voltage) for a period of time.
pulse fall time - Time for a pulse to decrease from 90% of its peak value to 10% of its peak value.
pulse repetition frequency - The number of times per second that a pulse is transmitted. Pulse rate.
pulse repetition time - Time interval between the start of two consecutive pulses.
pulse rise time - Time required for a pulse to increase from 10% of its peak value to 90% of its peak value.
pulse width - Time interval between the leading edge and trailing edge of a pulse at a point where the amplitude is 50% of the peak value.
push>push-pull amplifier - Amplifier using two active devices operating 180° apart.
Pythagorean theorem - A theorem in geometry: The square of the hypotenuse of a right triangle equals the sum of the squares of the other two sides. In electronics used for vector analysis of AC circuits
Q - Quality factor of an inductor or capacitor. It is the ratio of a component's reactance (energy stored) to its effective series resistance (energy dissipated). For a tuned circuit, a figure of merit used in bandwidth calculations. Q is the ratio of reactive power to resistive power in a tuned circuit. Also the symbol for charge in coulombs (Q for quantity).
quiescent - At rest. For an amplifier the term is used to describe a condition with no active input signal.
quiescent point - (Q point) A point on the DC load line of a given amplifier that represents the quiescent (no signal) value of output voltage and current for the circuit.
radar - Acronym for "radio detection and ranging" A system that measures the distance and direction of objects.
radio astronomy - Branch of astronomy that studies the radio waves generated by celestial bodies and uses these emissions to obtain information about them.
radio broadcast - Transmission of music, voice and other information on radio carrier waves that can be received by the general public.
radio communication - Term used to describe the transfer of information between two or more points by use of radio or electromagnetic waves.
radio-frequency amplifier - Amplifier having one or more active devices to amplify radio signals.
radio-frequency generator - Generator capable of supplying RF energy at any desired frequency in the radio-frequency spectrum.
radio-frequency probe - Probe used in conjunction with an AC meter to measure radio-frequency signals.
RC - Abbreviation for "resistance capacitance" also abbreviation for "radio controlled" as in "RC model airplanes."
RC time constant - Product of resistance and capacitance in seconds.
reactance - Symbol "X". Opposition to current flow without the dissipation of energy. Example: The opposition provided by inductance or capacitance to AC current.
reactive power - Also called imaginary power or wattles power. It is the power value in "volt amps" obtained from the product of source voltage and source current in a reactive circuit.
real number - Number having no imaginary part.
receiver - Unit or piece of equipment used to receive information.
recombination - Process by which a conduction band electron gives up energy (in the form of heat or light) and falls into a valence band hole.
rectangular coordinates - A Cartesian coordinate of a Cartesian coordinate system whose straight-line axes or coordinate planes are perpendicular.
rectangular wave - Also known as a pulse wave. A repeating wave that only operates between two levels or values and remains at one of these values for a small amount of time relative to the other value.
rectification - Process that converts alternating current to direct current.
rectifier - Diode circuit that converts alternating current into pulsating direct current.
reed relay - Relay consisting of two thin magnetic strips within a glass envelope. When a coil around the envelope is energized, the relay's contacts snap together making a connection between leads attached to the reed strips.
regenerative feedback - Positive feedback. Feedback from the output of an amplifier to the input such that the feedback signal is in phase with the input signal. Used to produce oscillation.
regulated power supply - Power supply that maintains a constant output voltage under changing load conditions.
regulator - Device or circuit that maintains a desired output under changing conditions.
relay - Electromechanical device that opens or closes contacts when a current is passed through a coil.
relative - Not independent. Compared with or with respect to some other measured quantity.
relaxation oscillator - Free running circuit that outputs pulses with a period dependent or one or more RC time constants.
reluctance - Resistance to the flow of magnetic lines of force.
remanence - Amount a material remains magnetized after the magnetizing force has been removed.
residual magnetism - Magnetism remaining in the core of an electromagnet after the coil current is removed.
resistance - Symbolized "R" and measured in ohms. Opposition to current flow and dissipation of energy in the form of heat.
resistive power - Amount of power dissipated as heat in a circuit containing resistive and reactive components. True power as opposed to reactive power.
resistive temperature detector - (RTD) Temperature detector consisting of a fine coil of conducting wire (such as platinum) that will produce a relatively linear increase in resistance as temperature increases.
receptivity - Measure of a material's resistance to current flow.
resistor - Component made of material that opposes flow of current and therefore has some value of resistance.
resistor color code - Coding system of colored stripes on a resistor to indicate the resistor's value and tolerance.
resonance - Circuit condition that occurs at the frequency where inductive reactance (XL) equals capacitive reactance (XC).
reverse bias - Bias on a PN junction that allows only leakage current (minority carriers) to flow. Positive polarity on the n-type material and negative polarity to the p-type material.
reverse breakdown voltage - Amount of reverse bias that will cause a PN junction to break down and conduct in the reverse direction.
reverse current - Current through a diode when reverse biased. An extremely small current also referred to as leakage.
reverse saturation current - Reverse current through a diode caused by thermal activity. This current is not affected by the amount of reverse bias on the component, but does vary with temperature.
RF - Abbreviation for "radio frequency."
rheostat - Two terminal variable resistor used to control current.
right angle triangle - Triangle having a 90° or square corner.
ripple frequency - Frequency of the ripple present in the output of a DC source.
ripple voltage - The small variations in Dc voltage that remain after filtering in a power supply.
rise time - Time for the leading edge of a pulse to rise from 10% of its peak value to 90% of its peak value.
RL differentiator - An RL circuit whose output voltage is proportional to the rate of change of the input voltage.
RL filter - Selective circuit of resistors and inductors that offers little or no opposition to certain frequencies while blocking or attenuating other frequencies.
RL integrator - RL circuit with an output proportionate to the integral of the input signal.
rms - Abbreviation for "root mean square"
rms value - Rms value of an AC sine wave is 0.707 times the peak value. This is the effective value of an AC sine wave. The rms value of a sine wave is the value of a DC voltage that would produce the same amount of heat in a heating element.
roll-off rate - Rate of change in gain when an amplifier is operated outside of its bandwidth.
rotary switch - Electromechanical device that has a rotating shaft connected to one terminal capable of making or breaking a connection to one or more other terminals.
R-2R ladder - Network or circuit composed of a sequence of L networks connected in tandem. Circuit used in digital to analog converters.
saturation - Condition in which a further increase in one variable produces no further increase in the resultant effect. In a bipolar junction transistor, the condition when the emitter to collector voltage is less than the emitter to base voltage. This condition puts forward bias on the base to collector junction.
sawtooth wave - Repeating waveform that rises from zero to maximum value linearly drops back to zero and repeats. A ramp waveform.
scale - Set of markings used for measurement.
schematic diagram - Illustration of an electrical or electronic circuit with the components represented by their symbols.
Schmitt trigger - Circuit to convert a given waveform to a square wave output.
Schottky diode - High speed diode that has very little junction capacitance. Also known as a "hot-carrier diode" or a "surface-barrier diode."
scientific notation - Numbers entered as a number from one to ten multiplied by a power of ten. Example: 8765 = 8.765 × 103.
secondary - Output winding of a transformer. Winding that is connected to a load.
secondary cell - Electrolytic cell used to store electricity. Once discharged may be restored by recharging by putting current through the cell in the direction opposite to that of discharge current.
selectivity - Characteristic of a circuit to discriminate between wanted and unwanted signals.
self biasing - Gate bias for a field effect transistor in which source current through a resistor produces the voltage for gate to source bias.
self inductance - Property that causes a counter electromotive force to be produced in a conductor when the magnetic field expands or collapses with a change of current.
semiconductor - An element which is neither a good conductor or a good insulator, but rather lies somewhere between the two. Characterized by a valence shell containing four electrons. Silicon, germanium and carbon are the semiconductors most frequently used in electronics.
series circuit - Circuit in which the components are connected end to end so that current has only one path to follow through the circuit.
series parallel network - Network that contains components connected in both series and parallel.
series resonance - Condition that occurs in a series LC circuit at the frequency where inductive reactance equals capacitive reactance. Impedance is minimum, current is maximum limited only by resistance in the circuit.
seven segment display - Device made of several light emitting diodes arranged in a numeric or alphanumeric pattern. By lighting selected segments numeric or alphabet characters can be displayed.
shells or bands - Orbital path containing a group of electrons having a common energy level.
shield - Metal grounded cover used to protect a wire, component or piece of equipment from stray magnetic and/or electric fields.
short circuit - Also called a short. Low resistance connection between two points in a circuit typically causing excessive current.
shunt resistor - Resistor connected in parallel or in shunt with another component or circuit.
signal - Electrical quantity that conveys information.
signal to noise ratio - Ratio of the magnitude of the signal to the magnitude of noise usually expressed in decibels.
silicon - (Si) Non metallic element (atomic number 14) used in pure form as a semiconductor.
silicon-controlled rectifier - (SCR) Three terminal active device that acts as a gated diode. The gate terminal is used to turn the device on allowing current to pass from cathode to anode.
silicon controlled switch - An SCR with an added terminal called an anode gate. A positive pulse either at the anode gate or the cathode gate will turn the device on.
silicon dioxide - Glass like material used as the gate insulating material in a MOSFET.
silicon transistor - A bipolar junction transistor using silicon as the semi conducting material.
silver - (Ag) Precious metal that does not easily corrode and is more conductive than copper.
silver mica capacitor - Mica capacitor with silver deposited directly onto the mica sheets instead of using conductive metal foil.
silver solder - Solder composed of silver, copper and zinc. Has a melting point lower than pure silver, but higher than lead-tin solder.
simplex - Communication in only one direction at a time. Example: FAX.
simulcast - Broadcasting a program simultaneously in two different forms, for example a program broadcast in both AM and FM.
sine - Sine of an angle of a right angle triangle is equal to the opposite side divided by the hypotenuse.
sine wave - Wave whose amplitude is the sine of a linear function of time. It is plotted on a graph that plots amplitude against time or radial degrees relative to the angular rotation of an alternator.
single in-line package - Package containing several electronic components (generally resistors) with a single row of connecting pins.
single pole double throw - (SPDT) Three terminal switch in which one terminal can be connected to either one of the other terminals.
single pole single throw - (SPST) Two terminal switch or relay that can open or close one circuit.
single sideband - (SSB) AM radio communication technique in which the transmitter suppresses one sideband and therefore transmits only a single sideband.
single throw switch - Switch containing only one set of contacts which can be either opened or closed.
sink - Device such as a load that consumes power or conducts away heat.
sintering - Process of bonding either a metal or powder by cold pressing it into a desired shape and then heating to form a strong cohesive body.
sinusoidal - Varying in proportion to the sine of an angle or time function. AC voltage in which the instantaneous value is equal to the sine of the phase angle times the peak value.
SIP - Abbreviation for "single in-line package."
skin effect - Tendency of high-frequency (rf) currents to flow near the surface layer of a conductor.
slew rate - The maximum rate at which the output voltage of an op-amp can change.
slide switch - Switch having a sliding button, bar or knob.
slow acting relay - Slow operating relay that when energized may not pull up the armature for several seconds.
slow-blow fuse - Fust that can withstand a heavy current (up to ten times its rated value) for a small period of time before it opens.
snap switch - Switch containing a spring under tension or compression that causes the contacts to come together suddenly when activated.
SNR - Abbreviation for "signal to noise ratio."
soft magnetic material - Ferromagnetic material that is easily demagnetized.
software - Program of instructions that directs the operation of a computer.
solar cell - Photovoltaic cell that converts light into electric energy. Especially useful as a power source for space vehicles.
solder - Metallic alloy used to join two metal surfaces.
soldering - Process of joining two metallic surfaces to make an electrical contact by melting solder (usually tin and lead) across them.
soldering iron - Tool with an internal heating element used to heat surfaces being soldered to the point where the solder becomes molten.
solenoid - An air core coil. Equipped with a movable iron core the solenoid will produce motion. As a result of current through the coil the iron core is pulled into the center of the winding. When the coil is deenergized, a spring pulls the movable core away from the center of the winding. Mechanical devices connected to the movable core are made to move as a result of current through the coil. Example: Electric door locks on some automobiles.
solid conductor - Conductor having a single solid wire instead of strands of fine wire twisted together.
solid state - Pertaining to circuits where signals pass through solid semiconductor material such as transistors and diodes as opposed to vacuum tubes where signals pass through a vacuum.
sonar - Acronym for "sound navigation and ranging." A system using reflected sound waves to determine the position of some target.
sonic - Pertaining to sound.
sound wave - Pressure waves propagated through air or other plastic media. Sound waves are generally audible to the human ear if the frequency is between approximately 20 and 20,000 vibrations per second. (hertz)
source - Device that provides signal power or energy to a load.
source follower - FET amplifier in which signal is applied between gate and drain with output taken between source and drain. Also called "common drain."
source impedance - Impedance through which output current is taken from a source.
south pole - Pole of a magnet into which magnetic lines of force are assumed to enter.
spark - Momentary discharge of electrical energy due to ionization of air or other dielectric material separating two charges.
SPDT - Single pole double throw.
speaker - Also called "loudspeaker." Transducer that converts electrical energy into mechanical energy at audio frequencies.
spectrum - Arrangement or display of light or other forms of electromagnetic radiation separated according to wavelength, energy or some other property.
spectrum analyzer - Instrument used to display the frequency domain of a waveform plotting amplitude against frequency.
speed-up capacitor - Capacitor added to the base circuit of a BJT switching circuit to improve the switching time of the device.
SPST - Abbreviation for "single pole single throw."
square wave - Wave that alternates between two fixed values for an equal amount of time.
static - Crackling noise heard on AM radio receivers. Caused by electric storms or electric devices.
static electricity - Stationary electric charges.
static reverse current - Reverse current through a zener diode when the reverse voltage across the diode is less than the zener voltage rating of the device.
stator - Stationary part of some rotary device such as a variable capacitor.
step-down transformer - Transformer in which the output AC voltage is less than the input AC voltage.
step-up transformer - Transformer in which the output AC voltage is greater than the input AC voltage.
stereo sound - System in which reproduced sound is delivered through two or more channels to give a sense of direction to the source.
stop band - Range of frequencies outside the pass band of a tuned amplifier.
storage time - In a BJT switching circuit, it is the time required for collector current to drop from 100% to 90% of its maximum value.
stranded conductor - Conductor composed of a group of strands of wire twisted together.
stray capacitance - Undesirable capacitance that exists between two conductors such as two leads or one lead and a metal chassis.
subassembly - Components contained in a unit for convenience in assembling or servicing equipment.
subatomic - Particles such as electrons, protons and neutrons that are smaller than atoms.
substrate - Mechanical insulating support upon which a device is fabricated.
summing amplifier - An op-amp circuit whose output is proportional to the sum of its instantaneous voltages.
superconductor - Metal such as lead or niobium that, when cooled to within a few degrees of absolute zero, can conduct current with no resistance.
super heterodyne receiver - Radio receiver that converts all radio frequencies to a fixed intermediate frequency to maximize gain and bandwidth before demodulation.
super high frequency - (SHF) Frequency band between 3 GHz and 30 GHz. So designated by Federal Communications Commission (FCC).
superposition theorem - Theorem designed to simplify networks containing two or more sources. It states that in a network containing more than one source, the current at any one point is equal to the algebraic sum of the currents produced by each source acting separately.
supply voltage - Voltage provided by a power source.
surface-barrier diode - (Schottky diode) High speed diode that has very little junction capacitance. Also known as a "hot-carrier diode."
surface leakage current - Diode reverse current that passes along the surface of the semiconductor materials.
surge current - High charging current that flows into a power supply filter capacitor as the power is first turned on.
sweep generator - Test instrument designed to produce a voltage that continuously varies in frequency over a band of frequencies. Used as a source to display frequency response of a circuit on an oscilloscope.
switch - Electrical device having two states, on (closed) or off (open). Ideally having zero impedance when closed and infinite impedance when open.
switching transistor - transistor designed to change rapidly between saturation and cut-off.
synchronization - Also called sync. Precise matching of two waves or functions.
synchronous - Two or more signals in step or in phase.
sync pulse - Pulse used as a reference for synchronization.
system - Combination of several pieces of equipment to perform in a particular manner.
tank circuit - Parallel resonant circuit containing only a coil and a capacitor. Both the coil and capacitor store electrical energy for part of each cycle.
tantalum capacitor - Electrolytic capacitor having a tantalum foil anode. Able to have a large capacity in a small package.
tap - Electrical connection to some point other than at the ends of a resistor or inductor.
tapered - Non unifrom distribution of resistance per unit length throughout the element of a potentiometer.
technician - Expert in troubleshooting circuit and system malfunctions. Along with a thorough knowledge of test equipment and how to use it to diagnose problems, the technician is also familiar with how to repair or replace faulty components. Technicians basically translate theory into action.
telegraphy - Communication between two points by sending and receiving a series of current pulses either through wire or by radio.
telemetry - Transmission of instrument readings to a remote location either by wire or by radio.
telephone - Apparatus designed to convert sound waves into electrical waves which are sent to and reproduced data distant point.
telephone line - Wires existing between subscribers and central stations in a telephone system.
telephony - Telecommunications system involving the transmission of speech information, allowing two or more persons to communicate verbally.
teletypewriter - Electric typewriter that like a tele-printer can produce coded signals corresponding to the keys pressed or print characters corresponding to the coded signals received.
television - System that converts both audio and visual information into corresponding electrical signals which are then transmitted through wires or by radio waves to a receiver which reproduces the original information.
telex - Teletypewriter exchange service.
temperature coefficient of frequency - Rate at which frequency changes with temperature.
tera - (T) Metric prefix that represents 1012.
terminal - Point at which electrical connections are made.
tesla - (T) Unit of magnetic flux density. (1 tesla = 1 Wb/m2).
test - Sequence of operations intended to verify the correct operation or malfunctioning of a piece of equipment or system.
thermal relay - Relay activated by a heating element.
thermal runaway - Problem that can develop in an amplifier when an increase in temperature causes an increase in collector current. The increase in collector current causes a further increase in temperature and so on. Unless the circuit is designed to prevent this condition, the device can be driven into saturation.
thermal stability - The ability of a circuit to maintain stable characteristics in spite of increased temperature.
thermistor - Temperature sensitive semiconductor that has a negative temperature coefficient of resistance. As temperature increases, resistance decreases.
thermocouple - Temperature transducer consisting of two dissimilar metals welded together at one end to form a junction that when heated will generate a voltage.
thermometry - Relating to the measuring of temperature.
thermostat - Device that opens or closes a circuit in response to changes in temperature.
Thevenin's theorem - Theorem that replaces any complex network with a single voltage source in series with a single resistance.
thick-film capacitor - Capacitor consisting of two thick-film layers of conductive film separated by a deposited thick-layer dielectric film.
thick film resistor - Fixed value resistor consisting of thick-film resistive element made from metal particles and glass powder.
thin film capacitor - Capacitor in which both the electrodes and the dielectric are deposited in layers on a substrate.
thin film detector - (TFD) A temperature detector containing a thin layer of platinum and used for precise temperature readings.
three phase supply - AC supply that consists of three AC voltages 120° out of phase with each other.
threshold - Minimum point at which an effect is produced or detected.
threshold voltage - For an enhancement MOSFET, the minimum gate source voltage required for conduction of source drain current.
thyristor - A term used to classify all four layer semiconductor devices. SCRs and triacs are examples of thyristors.
time constant - (t) Time required for a capacitor in an RC circuit to charge to 63% of the remaining potential across the circuit. Also time required for current to reach 63% of maximum value in an RL circuit. Time constant of an RC circuit is the product of R and C. Time constant of an RL circuit is equal to inductance divided by resistance.
time division multiplexing - (TDM) Transmission of two or more signals on the same path, but at different times.
time-domain analysis - A method of representing a waveform by plotting amplitude over time.
toggle switch - Spring loaded switch that is put in one of two positions either on or off.
tolerance - Permissible deviation from a specified value normally expressed as a percentage.
TO package - Cylindrical, metal can type of package of some semiconductor components.
toroidal coil - Coil wound on a doughnut shaped core.
transconductance - Also called mutual conductance. Ratio of a change in output current to the change in input voltage that caused it.
transducer - Device that converts energy from one form to another.
transformer - Inductor with two or more windings. Through mutual inductance, current in one winding called a primary will induce current into the other windings called secondaries.
transformer coupling - Also called inductive coupling. Coupling of two circuits by means of mutual inductance provided by a transformer.
transistor - Term derived from "transfer resistor." Semiconductor device that can be used as an amplifier or as an electronic switch.
transmission - Sending of information.
transmission line - Conducting line used to transmit signal energy between two points.
transmitter - Equipment used to achieve transmission.
triac - Bidirectional gate controlled thyristor similar to an SCR, but capable of conducting in both directions. Provides full wave control of AC power.
triangular wave - A repeating wave that has equal positive going and negative going ramps. The ramps have linear rates of change with time.
trigger - Pulse used to initiate a circuit action.
triggering - Initiation of an action in a circuit which then functions for a predetermined time. Example: The duration of one sweep in a cathode ray tube.
trimmer - Small value variable capacitor, resistor or inductor used to fine tune a larger value.
trivalent element - One having three valence electrons. Used as an impurity in semiconductor material to produce p-type material. Most commonly used trivalent elements are: Aluminum, Gallium and Boron.
troubleshooting - Systematic approach to locating the cause of a fault in an electronic circuit or system.
tuned circuit - Circuit that can have its component values adjusted so that it responds to one selected frequency and rejects all others.
tunnel diode - Heavily doped junction diode that has negative resistance in the forward direction of its operating range.
turn-off time - Sum of storage time and fall time.
turn-on time - Sum of delay time and rise time.
turns ratio - Ratio of the number of turns in the secondary winding of a transformer to the number of turns in the primary winding.
two phase - Two repeating waveforms having a phase difference of 90°.
UHF - Abbreviation for "ultra high frequency.
ultrasonic - Signals that are just above the frequency range of human hearing of approximately 20 kHz.
uncharged - Material having atoms with the same number of electrons in orbit as the number of protons in the nucleus. Having no electrical charge.
unijunction transistor - Three terminal device that acts as a diode with its own internal voltage divider biasing circuit.
unity gain frequency - Frequency of operation for a device where the gain of the component drops to unity.
VA - Abbreviation for "volt ampere"
vacuum tube - Electron tube evacuated to such a degree that its electrical characteristics are essentially unaffected by the presence of residual gas or vapor. Have been essentially replaced by transistors for amplification and rectification. Cathode ray tubes are still used as display devices.
valence shell - The outermost electron shell for a given atom. The number of electrons in this shell determines the conductivity of the atom.
varactor diode - PN junction diode with a high junction capacitance when reverse biased. Most often used as a voltage controlled capacitor. The varactor is also called: varicap, tuning diode and epicap.
variable capacitor - Capacitor whose capacitance can be change by varying the effective area of the plates or the distance between the plates.
variable resistor - Resistor whose resistance can be changed by turning a shaft. See also "potentiometer and rheostat."
VCR - Abbreviation for "video cassette recorder."
vector - Quantity having both magnitude and direction. Normally represented by a line. Length of the line indicates magnitude and orientation indicates direction.
vector diagram - Arrangement of vectors showing phase relationships between two or more AC quantities of the same frequency.
vertical MOS - Enhancement type MOSFET designed to handle much greater values of drain current than standard E-MOSFET.
very high frequency - (VHF) Electromagnetic frequency band from 30 MHz to 300 MHz.
very low frequency - (VLF) Frequency band from 3 kHz to 30 kHz.
video - Relating to any picture or visual information. From the latin word meaning "I see."
video amplifier - Amplifier having one or mare stages designed to amplify video signals.
virtual ground - Point in a circuit that is always at approximately ground potential. Often a ground for voltage, but not for current.
voice coil - Coil attached to the diaphragm of a moving coil loudspeaker. The coil is moved through an air gap between magnetic pole pieces.
voice synthesizer - Synthesizer that can simulate speech by stringing together phonemes.
volt - Unit of potential difference or electromotive force. One volt is the potential difference needed to produce one ampere of current through a resistance of one ohm.
voltage - (V) Term used to designate electrical pressure or force that causes current to flow.
voltage amplifier - Amplifier designed to build up signal voltage. By design amplifiers can have a large voltage gain or a large current gain or a large power gain. Voltage amplifiers are designed to maximize voltage gain often at the expense of current gain or power gain.
voltage controlled oscillator - Oscillator whose output frequency depends on an input control voltage.
voltage divider - Fixed or variable series resistor network connected across a voltage to obtain a desired fraction of that voltage.
voltage divider biasing - Biasing method used with amplifiers in which two series resistors connected across a source. The junction of the two biasing resistors provides correct bias voltage for the amplifier.
voltage drop - Voltage or difference in potential developed across a component due to current flow.
voltage feedback - Feedback configuration where a portion of the output voltage is fed back to the input of an amplifier.
voltage follower - Operational amplifier circuit characterized by a high input impedance, low output impedance and unity voltage gain. Used as a buffer between a source and a low impedance load.
voltage gain - Also called voltage amplification. Ratio of amplifier output voltage to input voltage usually expressed in decibels.
voltage multiplier - Rectifier circuit using diodes and capacitors to produce a DC output voltage that is some multiple of the peak value of AC input voltage. Cost effective way of producing higher DC voltages. Voltage doublers and voltage triplers are examples.
voltage rating - Maximum voltage a component can withstand without breaking down.
voltage regulator - Device or circuit that maintains constant output voltage (within certain limits) in spite of changing line voltage and/or load current.
voltage source - Circuit or device that supplies voltage to a load.
voltaic cell - Primary cell having two unlike electrodes immersed in a solution that chemically interacts to produce a voltage.
volt-ampere - Unit of apparent power in an AC circuit containing capacitive or inductive reactance. Apparent power is the product of source voltage and current.
voltmeter - Instrument used to measure difference in potential between two points.
volume - Magnitude or power level of audio frequency. Measured in volume units (VU).
watt - Unit of electrical power required to do work at the rate of one joule per second. One watt of power is expended when one ampere of direct current flows through a resistance of one ohm. In an AC circuit, true power is the product of effective volts and effective amperes, multiplied by the power factor.
wattage rating - Maximum power a device can safely handle continuously.
watt-hour - Unit of electrical work, equal to a power of one watt being absorbed for one hour.
wattmeter - Instrument used to measure electric power in watts.
wave - Electric, electromagnetic, acoustic, mechanical or other form whose physical activity rises and falls or advances and retreats periodically as it travels through some medium.
waveform - Shape of a wave.
waveguide - Rectangular or circular pipe used to guide electromagnetic waves at micro frequencies.
wavelength - (l) Distance between two points of corresponding phase and is equal to waveform velocity divided by frequency.
weber - (Wb) Unit of magnetic flux. One weber is the amount of flux that when linked with a single turn of wire for an interval of one second will induce an electromotive force of one volt.
wien-bridge oscillator - Oscillator that uses an RC low-pass filter and an RC high-pass filter to set the frequency of oscillations.
wet cell - Secondary cell using a liquid as an electrolyte.
wetting - Term used in soldering to describe the condition that occurs when the metals being soldered are hot enough to melt the solder so it flows over the surface.
wheatstone bridge - Four arm bridge circuit used to measure resistance, inductance or capacitance.
wideband amplifier - Also called "broadband amplifier." Amplifier with a flat response over a wide range of frequencies.
winding - One or more turns of a conductor wound in the form of a coil.
wire - Single solid or stranded group of conductors having a low resistance to current flow. Used to make connections between circuits or points in a circuit.
wire gauge - American wire gauge (AWG) is a system of numerical designations of wire diameters.
wireless - Term describing radio communication that requires no wired between two communicating points.
wire wound resistor - Resistor in which the resistive element is a length of high resistance wire or ribbon usually nichrome wound onto an insulating form.
wire wrapping - Method of making a connection by wrapping wire around a rectangular pin.
woofer - Large loudspeaker designed primarily to reproduce low frequency audio signals.
work - Work is done any time energy is transformed from one type to another. The amount of work done is dependent on the amount of energy transformed.
X - Symbol for reactance
X aY - Symbol for admittance.
Y axis - Vertical axis.
xis - Horizontal axis
Z axis - Axis perpendicular to both X and Y axes.
Zener Diode - Semiconductor diode in which reverse breakdown voltage current causes the diode to develop a constant voltage. Used as a clamp for voltage regulation.
Zeroing - Calibrating a meter so that it shows a value of zero when zero is being measurе.
Job hunting or job seeking is the act of looking for employment, due to unemployment or discontent with a current position. The immediate goal of job seeking is usually to obtain a job interview with an employer which may lead to getting hired. The job hunter or seeker typically first looks for job vacancies or employment opportunities. Common methods of job hunting are:
*
using a job search engine
* looking through the classifieds in newspapers
* using a private or public employment agency or recruiter
* finding a job through a friend or an extended business network or personal network
IV. Job hunting
Language notes
Position должность
Application заявление
Promising перспективный
Creativе творческий
Competitive конкурентоспособный
Responsibility ответственность
Skillful умелый. опытный,
Negotiations переговоры,
Entrepreneur предприниматель,
Fair честный,
Reliability надежность,
Letter of Recommendation рекомендательное письмо,
length продолжительность,
Experimental period испытательный срок,
environment окружающая среда,
excellent references прекрасные отзывы,
job работа,
Officer должностное лицо,
To earn зарабатывать
Charge оплата любых услуг,
Salary зарплата служащих,
Wages зарплата рабочих
Bonus премия,
Labour contract (agreement) трудовое соглашение
Deadline конечный срок подачи чего-то,
junior младший по работе,
Red tape (разг) канцелярская (бумажная работа),
senior старший по работе,
Word combinations
1)You have excellent references from your previous job
У вас прекрасные отзывы с предыдущей работы.
2) What do you consider a fair salary?
Какую зарплату Вы считаете достойной Вас?
3)The hours are from nine to five thirty
Мы работаем с девяти до половины шестого.
4) Tell him not to sign the contract
Скажите ему, чтобы он не подписывал контракт.
5) I am a Marketing Manager – So am I.
Я работаю менеджером по вопросам маркетинга.- Я тоже.
Applying
One can also go and hand out résumés or Curriculum Vitae to prospective employers. Another recommended method of job hunting is to use cold calling or emailing to companies that one desires to work for and inquire to whether there are any job vacancies.
Interviewing
Once an employer has received your résumé, they will make a short list of potential employees to be interviewed based on the resume and any other information contributed. During the interview process, interviewers generally look for persons who they believe will be best for the job and work environment. The interview may occur in several rounds until the interviewer is satisfied and offers the job to the applicant.
Types of Jobs
There are several types of jobs, including full-time long-term regular jobs, internship, or contract jobs.
Job-hunter — ˈjob ˌhunter noun [countable] someone who is looking for a job; =job seeker: • She had just embarked on a job hunt in Chicago
Before You Start Job Hunting
Your cover letter and resume or CV is typically the first impression an employer will have of you. It needs to market your relevant skills, knowledge, and accomplishments. The right resume and cover letter is one of the most critical job search tools you can have. Once your resume is in order you'll need to send it out via email or snail mail or post it online. Our Resume and Cover Letter Center steps you through writing, publishing, posting, and submitting your resume and cover letter to employers and to jobs web sites.
Tips
for Effective Job Hunting
It's always important to make sure you have covered all the bases when you are
in the midst of a job search. Review these ten tips to make sure your job
hunting is on the right track.
Electronics is a field of engineering and applied physics dealing with the design and application of electronic circuits. The operation of circuits depends on the flow of electrons for generation, transmission, reception and storage of information.
Today it is difficult to imagine our life without electronics.It surrounds use everywhere. Electronic devices are widely used in scientific research and industrial designing, they control the work of plants and power stations, calculate the trajectories of space ships and help the people discover new phenomena of nature.
Automatization of production processes and studieson living organisms became
possible due to electronics.The invention of vacuum tubes at the beginning of the 20th
century was, the starting point of the rapid growth of modern electronics.
Vacuum tubes assisted in manipulation of signals.
The development of a large variety of tubes designed for specialized functions
made possible the progress in radiocommunication technology before the World War II
and in the creation of early computers during and shortly after the war.
The transistor invented by American scientists W Shockly, J.Bardeen and W Brattain in 1948 completely replaced the vacuum tube.
The transistor, a small piece of a semi conductor with three electrodes, had
great advantages over the best vacuum tubes.
It provided the same functions as the vacuum
tube but at reduced weight, cost,
power consumption, and with highreliability.
With the invention of the transistor all essential circuit functions
could be carried out inside solid bodies. The aim of creating electronic circuits
with entirely solid state components had
finally been realized.
Early transistors could respond at a rate of a few million times a second.
This was fast enough to serve in radio circuits, but far below the speed needed for high speed computers or for microwave communication systems.
The progress in semiconductor technology led to the development of the
integrated circuit, which was discovered due to the efforts of John Kilby in1958.
There appeared a new field of science — integrated electronics.
The essence of it is batch processing. Instead of making, testing and assembling descrete components on a chip one at a time, large groupings of these components together
with their interconnections were made all at a time.
I would like to tell you about telecommunications and their developing.
We can not deny the role of telecommunications in our life. The Internet, phones, telegraph, cell phones, radio, television are all the means of communication or telecommunication. Nowadays we live in information era, when information is the key and engine of progress. Our society needs perfect means of information exchange that is why all types of telecommunication are under the permanent developing.
Currently hundreds of millions of people use wireless communication means. Cell phone is no longer a symbol of prestige but a tool, which lets to use working time more effectively. Considering that the main service of a mobile connection operator is providing high quality connection, much attention in the telecommunication market is paid to the spectrum of services that cell network subscriber may receive.
Today we can easily connect to the Internet using our cell phone or to take a picture or to take a short movie, using our video cell phone.
Late in the nineteenth century, communication facilities were augmented by a new invention — telephone. In the USA its use expanded slowly and by 1900 the American Telephone and Telegraph Company controlled 855,000 telephones.
After 1900, telephone installations extended much more rapidly in all the wealthier countries. The number of telephones in use in the world grew at almost 100 per cent per decade. But long-distance telephone services gradually developed and began to compete with telegraphic business. A greater contribution to long-range communication came with the development of wireless technology.
Before the outbreak of the First World War wireless telegraphy was established as a means of regular communication with ships at sea and provided a valuable supplement to existing telegraph lines. In the next few years the telephone systems of all the chief countries were connected with each other by radio. Far more immediate was the influence that radio had through broadcasting and by television, which followed it at an interval of about twenty-five years.
Telephones are as much a part of infrastructure of our society as roads or electricity, and competition will make them cheaper. Losses from lower prices will be countered by higher usage. Most important of all, by cutting out the need to install costly cables and microwave transmitters, the new telephones could be a boon to the remote and poor regions of the earth. Even today, half the world's population lives more than two hours away from a telephone.
Satellite phones are not going to deliver all their benefits at once.
Computer is not an acronym and sometimes abbreviated as comp or'puter. The term "computer" was originally given to humans (human computers) who performed numerical calculations using mechanical calculators, such as the abacus and slide rule. The term was later given to a mechanical device as they began replacing the human computers. Today's computers are electronic devices that accept data (input),process that data, produce output, and then store (storage) the results.
The first digital computer and what most people think of as a computer was called the ENIAC, built during World War II (1943-1946). Early computers like the ENIAC used vacuum tubes and were large (sometimes room size) and only found in businesses, Universities, or governments. Later, computers began utilizing transistors as well as smaller and cheaper parts that allowed the common person to own a computer.
Today, computers help make jobs that used to be complicated much simpler. For example, you can write a letter in a word processor, edit it anytime, spell check, print copies, and send it to someone across the world in a matter of seconds. All of these activities would have taken someone days, if not months, to do before computers. Also, all of the above is just a small fraction of what computers can do.
Today's computers have some or all of the below components (hardware). As technology advances, older technologies, such as a floppy disk drive and Zip drive (both shown below), are no longer required or included with computers.
Floppy disk driveA computer does not need all of the components mentioned above. However, a computer cannot work without having at the very minimum the below parts.
Computer hardware refers to the physical components that make up a computer system.
There are many different kinds of hardware that can be installed inside, and connected to the outside, of a computer.
Computer hardware may sometimes be seen abbreviated as computer hw.
Abbreviated as HW, Hardware is best described as any physical component of a computer system that contains a circuit board, ICs, or other electronics. A perfect example of hardware is the screen on which you are viewing this page. Whether it be acomputer monitor, tablet or smartphone; it's hardware.
Without any hardware, your computer would not exist, and software could not be used. The picture is aLogitech webcam, an example of an external hardwareperipheral. This hardware device allows users to take videos or pictures and transmit them over the Internet.
Below is a list of external hardware and internal hardware that may be found with a computer.
Vocabulary.
ü telephone book (directory) – телефонная книга
ü telephone booth (box phone) – телефон-автомат
ü directory enquiries – телефонная служба
ü switchboard operator – телефонист, оператор
ü general call – общий звонок
ü emergency call – экстренный звонок
ü local call – местный звонок
ü personal call – индивидуальный звонок
ü IDD (international direct dialing) – прямой международный звонок
ü to book (to order) the call – заказать звонок
ü to answer the call – ответить на звонок
ü to make a call (to call, to ring up) – сделать звонок
ü to call back (to call later, to return the call) – перезвонить
ü to misdial – неправильный звонок
ü go ahead – разговаривать
ü to hang up (to ring off, to put down the receiver) – вешать трубку
ü the line is free(clear) – свободная линия
ü to put down (to write down) a telephone number – записать номер телефона
ü to speak more loudly (to speak up) – разговаривать громко
Learning how to communicate well on the telephone is one of the top priorities for many people who need to use English at work. Learning the common phrases that are used on the telephone helps us to know what to expect. Telephoning requires special skills as there are a number of difficulties that arise when telephoning that are specific to telephoning. The first and foremost difficulty is not being able to see the person you are communicating with. This lack of visual communication often makes people, who can communicate quite successfully in other situations, nervous and thereby hinders their communicative abilities.
We do not telephone to someone. No preposition is needed:
We make a phone call
We dial a number
We contact someone by phone
We give someone a call
We give someone a ring
We telephone someone
We get hold of someone
We get in touch with someone
English business telephone talks are clearly structured and strongly intended. According to their intentions or purposes they can be easily classified into the following general groups: giving information, requesting information, confirming information, making arrangements, persuading the called party, negotiating and complaining.
The most obvious thing is to plan your telephone call; know the name of a person whom you want to speak to, and what you want to say. The techniques of telephoning are very much the same in all countries. Only remember your good telephone manners.
Advices
ü When talking on the telephone - speak clearly - Do not shout.
ü Make sure that your conversation with a busy person is as brief as possible.
ü When you get a wrong number don’t ask: “What number is this?” It is a good manner to ask: “Is this two -three -four -five -six?” If not – apologize. If a wrong number call comes through don’t lose your temper. Simply say: “Sorry, wrong number” – and hang up.
ü Always identify yourself when making a call, especially if you are calling on business, e. g. “This is Mr Brown of the British Trade Mission. Could I speak to Mr Jones...”
ü If you have a visitor do not carry on a long chat your visitor tries hard to avoid listening to your conversation. The best thing to do is to say you are busy at the moment and ... “May I call you back in a little while?” But don’t forget to do so.
Useful word-combinations.
|
answer |
to say "hello" into the phone when it rings |
|
answering machine |
something that you can record a message on if the person you are calling isn't home |
|
busy signal |
a beeping sound that tells the caller that the other person is already on the phone with someone else |
|
call |
a telephone conversation; to telephone |
|
caller |
the person who telephones |
|
call back/phone back |
to call someone who called you first |
|
call display |
a screen that shows you who is calling |
|
cellular phone/cell phone |
a telephone that you can take with you away from your house; mobile phone |
|
dial |
to press the buttons on the phone |
|
dial tone |
the sound the phone makes when you pick it up |
|
directory/phone book |
a book that alphabetically lists local phone numbers of people and businesses |
|
hang up |
to put the receiver down and end a call |
|
operator |
a person who answers telephone-related questions when you dial "0" |
|
phone |
a telephone; to telephone |
|
phone booth/pay phone |
a place where you can pay to use a telephone in public |
|
pick up |
to answer the phone |
|
receiver |
the piece on the phone that you speak into and listen from |
|
ring |
the sound a phone makes when somebody calls; to make that sound |
|
ringer |
the sound-piece that alerts a person that a call is coming through |
- Hello. Pizza Delivery. Can I help you?
- Hi. Yes, I’ve been working all day and I am really hungry. Can I order a pizza, please?
- Sorry. Could you speak a bit louder, please? I can’t hear you.
- Okay. I’d like to have a hot Pepperoni pizza, please. Is your home delivery service free?
- I’m so sorry. I didn’t catch that again. Are you going to have a pizza?
- Yes. That’s right, mam.
- Can you speak a little slower, please? Did you say that you want a vegetarian pizza? Is that right?
- No, I didn’t. It’s strange but I can hear you quite well.
- Oh, my god. There’s a lot of background noise – I can barely hear you. And I’m struggling to understand. Well… Hang on one second, please. I’ll go and turn off the radio.
- Sorry. What did you say? Will you speak up, please?... Hello! … We seem to have a bad connection on this phone. Okay. I think I have to choose someone else. Sorry about that anyway. Bye!
- Hello! … Apparently we got cut off.
- Good afternoon. «Tower Investment Bank». May I help you?
- Hi. I would like to talk to Mr. Clinton from the accounting department, please.
- May I ask you who is calling?
- My name is Bruno Ponti. I’m calling from an advertising agency.
- Thank you, Mr. Ponti. Just a moment, please. Let me check if Mr. Clinton is in his office.
- Sure.
- Thank you for waiting. I’m sorry but Mr. Clinton isn’t available at the moment. Would you like to leave a message or shall I ask him to call you back? Does he have your number?
- I believe he does. But I can give it to you, just in case.
- All right. Go ahead, please.
- My number is 046 78345.
- OK. And would you mind repeating your name?
- Sure. Bruno Ponti. I can spell it: B-R-U-N-O P-O-N-T-I.
- Thank you, Mr. Ponti. I’ll ask Mr. Clinton to call you back as soon as possible today.
- Thanks a lot. Bye.
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BATTERYBattery, in electricity and electrochemistry, any of a class of devices that convert chemical energy directly into electrical energy. Although the term battery, in strict usage, designates an assembly of two or more galvanic cells capable of such energy conversion, it is commonly applied to a single cell of this kind.
Every battery (or cell) has a cathode, or positive plate, and an anode, or negative plate. These electrodesmust be separated by and are often immersed in anelectrolyte that permits the passage of ions between the electrodes. The electrode materials and theelectrolyte are chosen and arranged so that sufficien telectromotive force (measured in volts) and electric current (measured in amperes) can be developed between the terminals of a battery to operate lights, machines, or other devices. Since an electrode contains only a limited number of units of chemical energy convertible to electrical energy, it follows that a battery of a given size has only a certain capacity to operate devices and will eventually become exhausted. The active parts of a battery are usually encased in a box with a cover system (or jacket) that keeps air outside and the electrolyte solvent inside and that provides a structure for the assembly.
Commercially available batteries are designed and built with market factors in mind. The quality of materials and the complexity of electrode and container design are reflected in the market price sought for any specific product. As new materials are discovered or the properties of traditional ones improved, however, the typical performance of even older battery systems sometimes increases by large percentages.
Batteries are divided into two general groups: (1) primary batteries and (2) secondary, or storage, batteries. Primary batteries are designed to be used until the voltage is too low to operate a given device and are then discarded. Secondary batteries have many special design features, as well as particular materials for the electrodes, that permit them to be reconstituted (recharged). After partial or complete discharge, they can be recharged by the application of direct current (DC) voltage.
The history of mobile phones, covers mobile communication devices which connect wirelessly to the public switched telephone network.
While the transmission of speech by radio has a long history, the first models that were wireless, mobile, and also capable of connecting to the standard telephone network are much more recent. The first such devices were barely portable compared to today's compact hand-held devices, and their use was clumsy.
Along with the process of developing more portable technology, and better interconnections system, drastic changes have taken place in both the networking of wireless communication and the prevalence of its use, with smartphones becoming common globally and a growing proportion of Internet access now done via mobile broadband.
In December 1947, Douglas H. Ring and W. Rae Young, Bell Labs engineers, proposed hexagonal cells for mobile phones in vehicles. At this stage, the technology to implement these ideas did not exist, nor had the frequencies been allocated. Two decades would pass before Richard H. Frenkiel, Joel S. Engel and Philip T. Porter of Bell Labs expanded the early proposals into a much more detailed system plan. It was Porter who first proposed that the cell towers use the now-familiar directional antennas to reduce interference and increase channel reuse (see picture at right) Porter also invented the dial-then-send method used by all cell phones to reduce wasted channel time.
In all these early examples, a mobile phone had to stay within the coverage area serviced by one base station throughout the phone call, i.e. there was no continuity of service as the phones moved through several cell areas. The concepts of frequency reuse and handoff, as well as a number of other concepts that formed the basis of modern cell phone technology, were described in the late 1960s, in papers by Frenkiel and Porter. In 1970 Amos E. Joel, Jr., a Bell Labs engineer, invented a "three-sided trunk circuit" to aid in the "call handoff" process from one cell to another. His patent contained an early description of the Bell Labs cellular concept, but as switching systems became faster, such a circuit became unnecessary and was never implemented in a system.
A cellular telephone switching plan was described by Fluhr and Nussbaum in 1973, and a cellular telephone data signaling system was described in 1977 by Hachenburg et al.
Fax, in full facsimile, also called telefax, in telecommunications, the transmission and reproduction of documents by wire or radio wave. Common fax machines are designed to scan printed textual and graphic material and then transmit the information through the telephone network to similar machines, where facsimiles are reproduced close to the form of the original documents. Fax machines, because of their low cost and their reliability, speed, and simplicity of operation, revolutionized business and personal correspondence. They virtually replaced telegraphic services, and they also present an alternative to government-run postal services and private couriers.
Most office and home fax machines conform to the Group 3 standard, which was adopted in 1980 in order to ensure the compatibility of digital machines operating through public telephone systems worldwide. As a standard letter-size sheet is fed through a machine, it is scanned repeatedly across its width by a charge-coupled device (CCD), a solid-state scanner that has 1,728 photosensors in a single row. Each photosensor in turn generates a low or high variation in voltage, depending on whether the scanned spot is black or white. Since there normally are 4 scan lines per mm (100 scan lines per inch), the scanning of a single sheet can generate almost two million variations in voltage. The high/low variations are converted to a stream of binary digits, or bits, and the bit stream is subjected to a source encoder, which reduces or “compresses” the number of bits required to represent long runs of white or black spots. The encoded bit stream can then be modulated onto an analogcarrier wave by a voice-band modem and transmitted through the telephone network. With source encoding, the number of bits required to represent a typewritten sheet can be reduced from two million to less than 400,000. As a result, at standard fax modem speeds (up to 56,000 bits per second, though usually less) a single page can be transmitted in as little as 15 seconds.
Communication between a transmitting and
a receiving fax machine opens with the dialing of
the telephone number of the receiving machine. This begins a process known as
the “handshake,” in which the two machines exchange signals that establish compatible
features such as modem speed, source code, and printing resolution. The page information
is then transmitted, followed by a signal that indicates no more pages are to
be sent. The called machine signals receipt of the message, and the calling
machine signals to disconnect the line.
At the receiving machine, the signal is demodulated, decoded, and stored for timed release to the printer. In older fax machines the document was reproduced on special thermally sensitive paper, using a print head that had a row of fine wires corresponding to the photosensors in the scanning strip. In modern machines it is reproduced on plain paper by a xerographic process, in which a minutely focused beam of light from a semiconductor laser or a light-emitting diode, modulated by the incoming data stream, is swept across a rotating, electrostatically charged drum. The drum picks up toner powder in charged spots corresponding to black spots on the original document and transfers the toner to the paper.
What is a Resistor?
An electric resistor is a two-terminal passive component specifically used to oppose and limit current. A resistor works on the principle of Ohm’s Law which states that voltage across the terminals of a resistor is directly proportional to the current flowing through it.
Ohm’s Law: V = IR
where V is the voltage applied across resistor,
I is the current flowing through it,
and R is the constant called resistance.
The unit of resistance is ohms.
Types of Resistors:
Resistors can be broadly classified based on the following criteria: the type of material used, the power rating and resistance value.
1. Fixed resistors.
In some scenarios, an electrical circuit may need a lesser amount of current to flow through it than the input value. Fixed resistors are used in these situations to limit the flow of current.
1.1 Carbon Composition Resistors:
These resistors are cylindrical rods which are a mixture of carbon granules and powdered ceramic. The resistor value depends on the composition of the ceramic material. A higher quantity of ceramic content will result in more resistance. Since the rod is coated with an insulated material, there are chances of damage due to excessive heat caused by soldering.
High current and voltage can also damage the resistor. These factors bring irreversible changes in the resistance power of these resistors. This type of resistor is rarely used nowadays due to their high cost and are only preferred in power supply and welding circuits.
1.2 Carbon film resistors:
This resistor is formed by depositing a carbon film layer on an insulating substrate. Helical cuts are then made through the carbon film to trace a long and helical resistive path. The resistance can be varied by using different resistivity carbon material and modifying the shape of the resistor. The helical resistive path make these resistors highly inductive and of little use for RF applications.
They exhibit a temperature coefficient between -100 and -900 ppm/ °C. The carbon film is protected either by a conformal epoxy coating or a ceramic tube. The operation of these resistors requires high pulse stability.
Capacitor is an electronic component that stores electric charge. The capacitor is made of 2 close conductors (usually plates) that are separated by a dielectric material. The plates accumulate electric charge when connected to power source. One plate accumulates positive charge and the other plate accumulates negative charge.
The capacitance is the amount of electric charge that is stored in the capacitor at voltage of 1 Volt.
The capacitance is measured in units of Farad (F).
The capacitor disconnects current in direct current (DC) circuits and short circuit in alternating current (AC) circuits.
Capacitor |
|
|
Polarized capacitor |
|
|
Variable capacitor |
|
|
The capacitance (C) of the capacitor is equal to the electric charge (Q) divided by the voltage (V):
C is the capacitance in farad (F)
Q is the electric charge in coulombs (C), that is stored on the capacitor
V is the voltage between the capacitor's plates in volts (V)
The capacitance (C) of the plates capacitor is equal to the permittivity (ε) times the plate area (A) divided by the gap or distance between the plates (d):
C is the capacitance of the capacitor, in farad (F).
ε is the permittivity of the capacitor's dialectic material, in farad per meter (F/m).
A is the area of the capacitor's plate in square meters (m2].
d is the distance between the capacitor's plates, in meters (m).
The total capacitance of capacitors in series, C1,C2,C3,.. :
The total capacitance of capacitors in parallel, C1,C2,C3,.. :
CTotal = C1+C2+C3+...
The capacitor's momentary current ic(t) is equal to the capacitance of the capacitor,
times the derivative of the momentary capacitor's voltage vc(t):
The capacitor's momentary voltage vc(t) is equal to the initial voltage of the capacitor,
plus 1/C times the integral of the momentary capacitor's current ic(t) over time t:
The capacitor's stored energy EC in joules (J) is equal to the capacitance C in farad (F)
times the square capacitor's voltage VC in volts (V) divided by 2:
EC = C × VC 2 / 2
ω = 2π f
ω - angular velocity measured in radians per second (rad/s)
f - frequency measured in hertz (Hz).
Cartesian form:
Polar form:
ZC = XC∟-90º
|
Variable capacitor has changeable capacitance |
|
|
Electrolytic capacitors are used when high capacitance is needed. Most of the electrolytic capacitors are polarized |
|
|
Spherical capacitor has a sphere shape |
|
|
Power capacitor |
Power capacitors are used in high voltage power systems. |
|
Ceramic capacitor has ceramic dielectric material. Has high voltage functionality. |
|
|
Tantalum oxide dielectric material. Has high capacitance |
|
|
High accuracy capacitors |
|
|
Paper capacitor |
Paper dielectric material |
Relay is a very important device now days. They are used in various circuits and many of us have problem of how to use a relay. With the help of this article I have tried to explain two things.
Working of relay
As we know relay is a device which is used to provide connection between two or more points or device in response to the input signal applied. In another words relay provide isolation between the controller and the device as we know devices may work on AC as well as on DC. However, they receive signals from microcontroller which works on DC hence we require a relay to bridge the gap. Relay is extremely useful when you need to control a large amount of current or voltage with small electrical signal.
Parts of Relay Switch
There are 5 parts in every relay -
1. Electromagnet- It consists of iron core wounded by coil of wires. When electricity is passed through it become magnetic therefore it is called as electromagnet.
2. Armature-The movable magnetic strip is known as armature. When current flowsthrough them, it energizes the coil and produce magnetic field which is used to make or break the normally open (N/O) or normally close (N/C) points. Armature can be moved with direct current (DC) as well as alternating current (AC).
3. Spring - When no current flow through coil electromagnet, the spring pulls the armature away so that circuit cannot be completed.
4. Set of electrical contacts- There are two contact points :
a. Normally open-In this the device connected to it will work when relay is activated and disconnect it when relay is inactive.
b. Normally close- In this the device connected to it will not work when relay is activated and the circuit is connected when relay is inactive.
5. Molded frame-Relays are covered with plastic or glass so that we can observe its working without opening or removing its cover.
Working of Relay
Working of relay is simple, when power is supplied to relay current start flowing through the control coil as a result electromagnetic starts energizing. Hear points A,B,C are used as control points. When power is applied to input terminal due to electromagnetic effect, B and C are connected thus closes the contacts causing a short circuit for the power to the load. If the relay was already de-energized when the contacts were closed, then thecontact move opposite and make an open circuit. When power supply is cut off point A and C are connected. This force is mainly provided by two factors they are spring and gravity.
WORKING OF SINGLE-POLE DOUBLE-THROW RELAY
SPDT relay is an electromagnetic switch consisting of a coil (terminals 85 & 86), 1 common terminal (30), 1 normally closed terminal (87a) and a normally open terminal (87).
Fig1. Poles of a SPDT Relay Switch
When the coil of the relay is at rest (not energized), the common terminal (30) and the normally closed terminal (87a) have continuity.
Fig2. Un-energized Relay Position
When the coil is energized, the common terminal (30) and the normally open terminal (87) have continuity.
Fig3. Energized Relay Position
Basically, the coil is an electromagnet that causes the arm that is always connected to the common (30) to pivot when energized thereby breaking contact with the normally closed terminal (87a) and making it with the normally open terminal (87).
Below is an example of how the connections are made to a load in a circuit using a SPDT relay switch?
Fig4. Connection of an SPDT Relay to Load
When the relay coil is energized, contact is established between the common (COM) and normally-open (NO) terminal thereby completing the supply connections to the load. Hence, the load is switched “on” when the relay is energized. Also check this article to understand the working of relays with the help of pictures, here - How Relay works
Different Types of Relay
1. Single Pole Single Throw (SPST)- these types of relay comprise of 4 terminals. Two terminals are used as coil points and other two can be used to connect or disconnect the circuit (A and B).
2. Single Pole Double Throw (SPDT)- these types of relay comprise of 5 terminals two for coil one for common terminal(C) and rest two can be connected to the common terminal.
3. Double Pole Single Throw (DPST)- these types of relay comprise of 6 terminal two for coil and other four for connecting and disconnecting two device. In other words it contains two SPST relay in one package.
4.DoublePole Double Throw(SPDT)- these types of relay comprise of 8 terminal two for coil and another two as common point and rest for connecting and disconnecting devices. In another words in this two SPDT relay are connected in one package.
FAMOUS PHYSICISTS
Alessandro Volta (1745-1827)
Alessandro Volta was an Italian physicist.
He invented electric baterry in 1800.
Georg Simon Ohm (1789-1854)
Georg Simon Ohm was a German physicist.
Ohm determined that the potential
difference (voltage) applied across a conductor
is directly proportional to electric current.
Now this relationship is known as Ohm’s law.
Andre – Marie Ampere (1775-1836)
Andre – Marie Ampere was a French physicist
who founded the science of electrodynamics
and electromagnetism. He demonstrated that
electric currents produce magnetic fields.
The unit of measurement of electric current,
the ampere, is named after him.
Voltage is the electrical force that would drive an electric current between two points.
· Voltage is a measure of the energy carried by the charge.
· Voltage is sometimes called the potential difference.
· Voltage is supplied by the battery.
· Voltage is used up in components, but not in wires, and we say voltage across a component.
· Voltage is measured in volts, V.
· Voltage is measured with voltmeter, connected in parallel.
· The symbol V is used for voltage in equations.
Voltage at a point and 0V (zero volts)
In electronics voltage at a point is the voltage difference between that point and a reference point of 0V (zero volts).
Zero volts could be any point in the circuit, but it is normally the negative terminal of the battery or power supply. Circuit diagrams are often labelled with 0V as a reminder.
CURRENT
Current is the rate at which electric charge flows past
a point in a circuit.
· Current is the rate of flow of charge.
· Current is not used up, what flows into a component
must flow out.
· We say current through a component.
· Current is measured in amps (amperes), A.
· Current is measured with an ammeter, connected in series. To connect in series you must break the circuit and connect the ammeter in the gap,
· The symbol I is used for current in equations.
The need to break the circuit to connect in series means that ammeters are difficult to use on soldered circuits. Most testing in electronics is done with voltmeters which can be easily connected without disturing circuits.
|
Current |
|
Voltage |
|
|
Symbol |
I |
|
V |
|
Definition |
Current is the rate at which electric charge flows past a point in a circuit. In other words, current is the rate of flow of electric charge. |
|
Voltage, also called electromotive force, is the potential difference in charge between two points in an electrical field. In other words, voltage is the "energy per unit charge”. |
|
Unit |
A or amps or amperage |
|
V or volts or voltage |
|
Relationship |
Current is the effect (voltage being the cause). Current cannot flow without Voltage. |
|
Voltage is the cause and current is its effect. Voltage can exist without current. |
|
Measuring Instrument |
Ammeter |
|
Voltmeter |
|
SI Unit |
1 ampere =1 coulomb/second. |
|
1 volt = 1 joule/coulomb. (V=W/C) |
|
Field created |
A magnetic field |
|
An electrostatic field |
|
In series connection |
Current is the same through all components connected in series. |
|
Voltage gets distributed over components connected in series. |
|
In a parallel connection |
Current gets distributed over components connected in parallel. |
|
Voltages are the same across all components connected in parallel. |
OHM’S LAW
Electric current can flow through a resistance when there is a voltage across that resistance. Ohm’s Law shows the relationship between the voltage (V), current (I) and resistance (R). It can be written in three ways:
or
where
V = voltage in volts (V)
I = current in amps (A)
R= resistance in ohms Ώ
or
V = voltage in volts (V)
I = current in milliamps (mA)
R= resistance in kilohms (k Ώ)
For most electronic circuits the amps is too large and the ohm is too small, so we often measure current in milliamps (mA) and resistance in kilohms (k Ώ).
1 mA = 0.001 A and 1 k Ώ – 1000 Ώ.
A wire is a single conductor which may have insulation (usually plastic).
A cable is a group of one or more flexible conductors (wires).
Single
core wire.
This is one solid wire with a plastic coating. It can be bent to shape but will break if bent many times.
Stranded wire cable.
It consist of many fine strands of wire covered by plastic insulation. It is flexible and can be bent many times.
Signal cable.
It consists of several colour – coded cores of stranded wire with plastic insulation.
Screened
cable.
The central wire carries the signal and the screen is connected to 0 V (common) to shield the signal from electrical interference. Screened cable is used for audio signals.
Co-axial cable
It is a screened cable for high frequency signals such as signals in TV antennas.
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2. Eric H. Glendinning, John McEvwan. Oxford English for Electronics. Oxford University Press.
3. English for telephoning David Gorden Smith Oxford Business English.
4. Толмачева Л.Ф.Учебное пособие по английскому языку для студентов транспортных ВУЗов Изд-во «Бастау». г. Алматы, 2001 г.
5. Raymond Murphy «English Grammar in Use» Second edition Cambridge University Press
6. И. П. Агабекян «Английский язык» 20 издание Ростов-на-Дону «Феникс» 2012 г
7. И. П. Агабекян «Английский язык» 20 издание Ростов-на-Дону «Феникс» 2012 г
8. «Англо-русский словарь сокращений по телекоммуникациям» А. В. Александров «Руссо» Москва 2002 г
9. В.К. Мюллер «Англо-русский Русско-английский словарь» Москва,2009 г.
10. Д. Коллин «Англо-русский русско-английский словарь с грамматическим приложением» Москва «Ладком» 2012 г.
11. Л. Д. Цесарский «After lessons» Пособие по Английскому языку для внеаудиторных занятий для средних специальных учебных заведений Москва «Высшая школа» 2001 г.
12. В. Франк, А. Досмаганбетова «Қазақ тілі» жоғарғы сынып оқушылары және студенттерге арналған анықтамалық. Алматы, 2006 ж.
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