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Electronics is the science that is based on and concerned with the controlled flow of electrons, or other carriers of electric charge (holes ), especially in semiconductor devices. It is one of the principal branches of electrical engineering.
When a beginner to electronics first looks at a circuit board full of components he/she is often overwhelmed by the diversity of do-dads. An electronic circuit is made up of electronic components. Electronic components are classified as active or passive.In order to learn electronics, one needs to study components, circuits and instruments used in electronics.
Active and Passive components.
Active components are those that are capable of controlling voltages or currents and can create a switching action in the circuit. Examples are transistors, diodes, etc.
Passive components is one that contributes no power gain (amplification) to a circuit or system. It has no control action and does not require any input other than a signal to perform its function. Examples are resistors, capacitors, inductors.
Resistors, Capacitors,etc., are known as passive components because they can only attenuate the electrical voltage and signals And cannot amplify. Whereas devices like transistors, operational amplifier(Op Amp) can amplify or increase the amplitude And energy associated with the signals. Hence the transistors and OpAmp come under active devices.
These components can be combined in different configurations by interconnecting them with conducting wires to build different useful Electronic circuits.
Electronic circuits:
An electronic circuit is composed of individual electronic components, such as resistors, transistors, capacitors, inductors and diodes, connected by conductive wires or traces through which electrical current can flow.
Circuits can be constructed of discrete components connected by individual pieces of wire, but now a days, it is much more common to create interconnections by photo lithographic techniques on a laminated substrate (a printed circuit board or PCB) and solder the components to these interconnections to create a finished circuit.
In an Integrated Circuit or IC, the components and interconnections are formed on the same substrate, typically a semiconductor such as silicon.
Breadboards, or strip boards are common for testing new designs. They allow the designer to make quick changes to the circuit during development.
An electronic circuit can usually be categorized as an analog circuit, a digital circuit or a mixed-signal circuit (a combination of analog circuits and digital circuits).
Analog Circuits:
Analog circuits are those in which current or voltage may vary continuously with time to correspond to the information being represented. An analogue signal is a fluctuating voltage which can have any numerical value. i.e it may be tiny fractions of a volt or it may be hundreds of volts. It may be a constant voltage or rapidly changing. Analog circuitry is constructed from two fundamental building blocks: series and parallel circuits. In a series circuit, the same current passes through a series of components. A string of Christmas lights is a good example of a series circuit: if one goes out, they all do. In a parallel circuit, all the components are connected to the same voltage, and the current divides between the various components according to their resistance.
Analog circuits are sometimes called linear circuits although many non-linear effects are used in analog circuits such as mixers, modulators, etc. Good examples of analog circuits include vacuum tube and transistor amplifiers, operational amplifiers and oscillators.
Digital circuits:
It processes signals with discreet values, digital signal. A digital signal can only have one of two possible values. We may refer to as High i.e '1' or Low, '0'. The exact value of these voltages depends on the particular type of digital circuit but one of the most common systems uses +5 volts and 0 volts. In this system the +5v is referred to as the digital High (or simply HI) and the 0v as digital Low (or LO).
Computers, electronic clocks, and programmable logic controllers (used to control industrial processes) are constructed of digital circuits.
Mixed circuits:
Mixed-signal or hybrid circuits contain elements of both analog and digital circuits. Examples include comparators, timers, PLLs, ADCs (analog-to-digital converters), and DACs (digital-to-analog converters). Most modern radio and communications circuitry uses mixed signal circuits. For example, in a receiver, analog circuitry is used to amplify and frequency-convert signals so that they reach a suitable state to be converted into digital values, after which further signal processing can be performed in the digital domain.
