Electronic amplifiers are special devices that increase the power, voltage or current of incoming signals. Their exact purpose and principles of operation depend on the specific type of device, of which there are many. They are used in recording studios, on television and radio, help in receiving Wi-Fi signals and signals from space. And this is not the whole list of functions, therefore it is difficult to overestimate the value of these devices.
Triodes and first amplifiers
At the beginning of the 20th century, the world was experiencing rapid development of technology. Engineering, industry, and energy developed. It was at this time that such a science as electronics was born. At first, it did not have wide practical application, but after half a century this direction has become most important for human civilization. Everything that people use these days would be impossible without the development of electronic technology. An important breakthrough of that period was the invention of a device called a triode.
The first model of this device was a glass lamp with three electrical contacts and was designed to change the input signal of an electric current. The change occurred by amplifying the input signal. So the first electronic amplifier in history appeared, which at the dawn of the century allowed a breakthrough in the communications industry - it was possible to create the first wireless telegraph.
General principles
The basic principle of operation of absolutely any electric signal amplifier, regardless of its functional purpose, is due to the fact that with small changes in the values of electric current and / or voltage at the input of the amplifier circuit, there is a significant increase in these parameters at the output, which can be applied in practice.
The main part of any amplifier is a device called a transistor. It consists of three separate semiconductor elements that have electrical contacts - this is the collector, base, emitter. When AC flows through them, depending on its direction, the transistor amplifies or attenuates the power of the input signal.
Amp Parameters
The most important characteristic of an amplifier is the gain, and it is equal to the ratio of the parameter value at the input to the parameter value at the output of the circuit. In fact, this indicator gives the main idea of the quality of the device and its capabilities. Another important parameter is the amplitude response. In fact, this is a functional dependence of the amplitude of the output indicators on the values of the input signal. The importance of this parameter is that this dependence is non-linear, which means that the circuit will react differently to different values of the signal at the input. The third important parameter of the electronic amplifier is the amplitude-frequency characteristic, which actually shows the dependence of the gain value on the frequency of the input signal. As it turns out in practice, at different AC frequencies, amplification occurs in different ways.
Classification
There are several signs by which these or other types of amplifiers are distinguished. The first is the frequency. Low-frequency devices are able to increase the rate by no more than a hundred kilohertz. In high-frequency ones, it grows in the range from 100 kHz to 100 MHz, sometimes a little more. There are also so-called “selective” devices operating in a certain small frequency range. The widest coverage of the fourth type of devices. Broadband can amplify from 10 Hz to 100 MHz.
Another typology is that devices contain an active element. It can be, for example, a transistor. There are semiconductor, microwave amplifiers, diode, tube.
One of the newest varieties is parametric, where the increase in signal power occurs through the energy of a generating external source. Occasionally, the capacitance of a nonlinear inductive element in an electric circuit changes. There are amplification devices on tunnel diodes that are used to transmit sound to radio receivers.
The classification by mode is better known. They are indicated by capital letters of the Latin alphabet. Until the 60s of the last century, there were only four classes: A, B, C, D. Subsequently, the technologies improved and became more complicated, additional types of modes, subclasses, amplifiers with alternating voltage appeared.
Broadcasting Basics
The most important negative factor affecting the quality of the TV signal is the distance from the source (TV tower). If the distance from the television tower is so high that the antenna is simply not able to catch the signal, it makes sense to include a television amplifier in the network.
A television signal is a complex electromagnetic pulse that carries video and audio information. Because of this, amplifiers for TV antennas are noticeably different from radio devices. There are many TV amplifiers, different in characteristics and functionality.
They are mainly divided into two categories - analog signal amplifiers and digital TV (DVB-T2). It is also worth taking into account that the choice of device depends on how many TV receivers you need to transmit the signal.
Mobile Application
The most important device for humans these days is, of course, a mobile phone. Today, there are several billion handheld communications equipment in the world. But what would be the use of them if mobile networks did not exist? The phone simply turns into an expensive toy when the subscriber is in places where there is no coverage of mobile signals. In each mobile device there is a communication amplifier. The fact is that one built-in antenna for receiving a signal from a mobile operator will not be enough due to the fact that the signal weakens with distance from the source.
In order for the communication to take place without interference, a special communication amplifier in the phone increases the power of the signal caught by the antenna and translates it into a form convenient for the subscriber. But sometimes even this built-in amplifier is not enough when coverage is too weak. And then special external amplifiers are used - repeaters that go separately from the telephone kit.
Wi-Fi Application
In the modern information age, it is difficult to imagine your life without access to the World Wide Web. The most popular type of wireless connection is undoubtedly Wi-Fi. However, this technology has a noticeable minus - a limited range. In the absence of obstacles, devices can receive the network at a distance of only 100 meters. This is not always convenient, especially for large companies or firms whose branches are located in different areas of the city.
A similar disadvantage is removed by WiFi amplifiers. These are special repeater devices that receive a weak electromagnetic signal, convert it to a more powerful one and relay them to nearby receivers of the Internet signal. WiFi amplifiers are increasingly becoming popular in the countryside, which makes this type of Internet connection no less popular than mobile.
Sound Frequency Change
A person is able to hear sound only within certain limits of perception. In fact, people cannot respond to sound signals with a frequency of over 20 thousand Hz. Ultrasonic waves are heard only by some species of animals, mainly leading nocturnal life. As for low-frequency, here the threshold for a person is from 16 Hz. Everything below is called infrasound. Similar waves are formed when a meteorite falls, during storms. But for the human ear, such signals are inaudible.
The frequency amplifier is used in many household appliances and appliances. These are televisions, radio transmitters, music centers. There are also separate special devices. Their essence is to achieve a certain frequency range equal to what the human brain is capable of perceiving. Low frequencies are converted, the oscillation power changes. Some devices have the ability to adjust the tones, volume level. With the built-in equalizer, you can even adjust the amplitude of the signal.
With the use of radio tubes
Vacuum tubes are used in tube amplifiers. Such devices are popular in recording studios and music reproduction. Their advantage is that in addition to obtaining suitable frequencies, it is possible to obtain additional tones. They are called harmonics, and if it is even or odd in semiconductor devices, in tube devices it is mainly only the first. The sound is cleaner, the music is better.
The power of tube amplifiers is lower than in transistor ones, but their circuitry is much simpler, without an abundance of complex parts. It is believed that such devices more naturally transmit sound, especially high frequency ranges. There may be problems playing bass. Therefore, it is recommended to listen to mainly vocal or jazz music using devices.
About candy bars
There is a variety of electronic amplifiers, which are called monoblock. Their influence extends to only one sound channel. Hence the term where "mono" means "single." Similar aggregates were used by musicians from fairly well-known bands such as the Grateful Dead. Amplifiers work on lamps, but exist with transistors. Their advantage: they provide excellent sound quality.
For stereo equipment will require two monoblocks. This is due to the effect on the right or left sound channel. In addition, it is advisable to purchase a preamplifier. Monoblocks - time-tested devices. They appeared one of the first of their kind and are widespread to this day. Disadvantages - a rather high price and special requirements for placement and use. Therefore, only professional musicians with the means can afford to equip such a sound system.