1. AMPLIFIERS – INTRODUCTION
Amplifiers are used extensively in electronic circuits to make an electronic signal bigger
without affecting it in any other way. Generally we think of Amplifiers as audio amplifiers in
the radios, CD players and stereo’s we use around the home.
An amplifier, electronic amplifier or
(informally) amp is an electronic device
that increases the power of a signal.
It does this by taking energy from a
power supply and controlling the output
to match the input signal shape but with
a larger amplitude. In this sense, an
amplifier modulates the output of the power supply to make the output signal stronger than
the input signal. An amplifier is effectively the opposite of an attenuator: while an amplifier
provides gain, an attenuator provides loss.
The first practical electronic device which could amplify was the
Audion (triode) vacuum tube, invented in 1906 by Lee De Forest
which led to the first amplifiers. The terms "amplifier" and
"amplification" (from the Latin amplificare, 'to enlarge or expand')
were first used for this new capability around 1915 when triodes
became widespread. For the next 50 years vacuum tubes were the
only devices which could amplify, and were used in all amplifiers
until the 1960s, when transistors began to be used. Most amplifiers
today use transistors, although tubes are still used.
,Worksheet No.1
Exercise 1. Reading Comprehension : Answer the questions.
1. What is an amplifier?
2. How does an amplifier work?
3. What was the first „amplifier“ called?
4. When and who was it invented by?
5. When did people begin to use transistors?
Exercise 2. Complete the highlighted words to the definitions.
1. to enlarge or expand - __________________
2. an increase in wealth or resources - __________________
3. __________________ are composed of individual electronic components, such as resistors,
transistors, capacitors, inductors and diodes, connected by conductive wires or traces through
which electric current can flow.
4. The __________________of a periodic variable is a measure of its change over a single
period (such as time or spatial period).
5. signal that comes out of an electronic system - __________________
6. __________________ are devices that control electric current through a vacuum in a sealed
container.
7. an electronic device that supplies electric energy to an electrical load - ________________
8. signal going into an electronic system - __________________
Exercise 3. Speaking
1. What amplifiers do you use daily around the home? Name the devices.
2. Do you know any famous amplifier brands? What is your favourite one?
3. What is the brand of your hi-fi audio, car, guitar, etc. amplifier?
, 2. SIGNAL
A signal as referred to in communication systems, signal processing, and electrical
engineering "is a function that conveys information about the behavior or attributes of some
phenomenon".
In the physical world, any quantity exhibiting variation in time or variation in space (such as
an image) is potentially a signal that might provide information on the status of a physical
system, or convey a message between observers, among other possibilities.
The IEEE (The Institute of Electrical and Electronics Engineers) Transactions on Signal
Processing states that the term "signal" includes audio, video, speech, image, communication,
geophysical, sonar, radar, medical and musical signals.
In electronics, a signal is an electric current or electromagnetic field used to convey data from
one place to another. The simplest form of signal is a direct current (DC) that is switched on
and off; this is the principle by which the early telegraph worked. More complex signals
consist of an alternating-current (AC) or electromagnetic carrier that contains one or more
data streams.
input signal - signal going into an electronic system (MP3, microphone, camera...)
output signal - signal that comes out of an electronic system (loudspeaker, oscilloscope,
another amplifier...)
Amplifiers are used extensively in electronic circuits to make an electronic signal bigger
without affecting it in any other way. Generally we think of Amplifiers as audio amplifiers in
the radios, CD players and stereo’s we use around the home.
An amplifier, electronic amplifier or
(informally) amp is an electronic device
that increases the power of a signal.
It does this by taking energy from a
power supply and controlling the output
to match the input signal shape but with
a larger amplitude. In this sense, an
amplifier modulates the output of the power supply to make the output signal stronger than
the input signal. An amplifier is effectively the opposite of an attenuator: while an amplifier
provides gain, an attenuator provides loss.
The first practical electronic device which could amplify was the
Audion (triode) vacuum tube, invented in 1906 by Lee De Forest
which led to the first amplifiers. The terms "amplifier" and
"amplification" (from the Latin amplificare, 'to enlarge or expand')
were first used for this new capability around 1915 when triodes
became widespread. For the next 50 years vacuum tubes were the
only devices which could amplify, and were used in all amplifiers
until the 1960s, when transistors began to be used. Most amplifiers
today use transistors, although tubes are still used.
,Worksheet No.1
Exercise 1. Reading Comprehension : Answer the questions.
1. What is an amplifier?
2. How does an amplifier work?
3. What was the first „amplifier“ called?
4. When and who was it invented by?
5. When did people begin to use transistors?
Exercise 2. Complete the highlighted words to the definitions.
1. to enlarge or expand - __________________
2. an increase in wealth or resources - __________________
3. __________________ are composed of individual electronic components, such as resistors,
transistors, capacitors, inductors and diodes, connected by conductive wires or traces through
which electric current can flow.
4. The __________________of a periodic variable is a measure of its change over a single
period (such as time or spatial period).
5. signal that comes out of an electronic system - __________________
6. __________________ are devices that control electric current through a vacuum in a sealed
container.
7. an electronic device that supplies electric energy to an electrical load - ________________
8. signal going into an electronic system - __________________
Exercise 3. Speaking
1. What amplifiers do you use daily around the home? Name the devices.
2. Do you know any famous amplifier brands? What is your favourite one?
3. What is the brand of your hi-fi audio, car, guitar, etc. amplifier?
, 2. SIGNAL
A signal as referred to in communication systems, signal processing, and electrical
engineering "is a function that conveys information about the behavior or attributes of some
phenomenon".
In the physical world, any quantity exhibiting variation in time or variation in space (such as
an image) is potentially a signal that might provide information on the status of a physical
system, or convey a message between observers, among other possibilities.
The IEEE (The Institute of Electrical and Electronics Engineers) Transactions on Signal
Processing states that the term "signal" includes audio, video, speech, image, communication,
geophysical, sonar, radar, medical and musical signals.
In electronics, a signal is an electric current or electromagnetic field used to convey data from
one place to another. The simplest form of signal is a direct current (DC) that is switched on
and off; this is the principle by which the early telegraph worked. More complex signals
consist of an alternating-current (AC) or electromagnetic carrier that contains one or more
data streams.
input signal - signal going into an electronic system (MP3, microphone, camera...)
output signal - signal that comes out of an electronic system (loudspeaker, oscilloscope,
another amplifier...)
