Analog electronics

Analog electronics are electronic systems with continuously variable signal i.e. small changes in input result in small changes in output. Analog signal invariably include noise; that is, random disturbances or variations.

The term “analogue” describes the proportional relationship between a signal and a voltage or current that represents the signal.

Voltage Rise and Voltage Drop

There are two kinds of voltage or potential difference. One is voltage Rise and voltage.

Voltage Rise: The energy introduced or added into a circuit is called a Voltage Vise.

Voltage Drop: The energy removed from the circuit by the load is called a Voltage Drop.

Thus, Voltage Rise=Voltage Drop.

Inductor and Capacitor

An inductor (or reactor) can store energy in a magnetic field created by the electric current passing through it. An inductor’s ability to store magnetic energy is measured, in units of henries. It is a conducting wire shaped as a coil; the loops help to create a strong magnetic field inside the coil. Inductors are used where current and voltage change with time, to delay and reshape alternating currents. Inductors called chokes are used as parts of filters in power supplies or to block AC signals from passing through a circuit.

A capacitor is a device for storing electric charge. Capacitors consist of a pair of conductors separated by a dielectric (insulator) for example; consist of metal foils separated by a layer of insulating film. When voltage is applied across the conductors, a static electric field develops across the dielectric, causing positive charge to collect on one plate and negative charge on the other plate. Energy is stored in the electrostatic field.

Capacitors are widely used in electronic circuits for blocking direct current while allowing alternating current to pass, in filter networks, for smoothing the output of power supplies, in the resonant circuits that tune radios to particular frequencies and for many other purposes.


It is also called VOM(Volt-Ohm meter) or a multitester, is an electronic measuring instrument to measure voltage, current and resistance. They may use analog or digital circuits.

It is usually hand-held device used for basic fault finding and field service as it can measure to a very high degree of accuracy. They can be used to troubleshoot electrical problems.


A transformer transfers electrical energy from one circuit to another through inductively coupled

conductors—it’s coils to efficiently raise or lower AC voltages. It cannot increase power so that if the voltage is raised, the current is proportionally lowered and vice versa.

Transformers can be a thumbnail-size inside a microphone to huge units used to interconnect portions of power grids. They are used in many different things like Computer network interface cards, modems and power amplifiers.


They are a class of crystalline solids with electrical conductivity between that of a conductor and an insulator. Such materials can be treated chemically to allow transmission and control of an electric current. Semiconductors are used in the diodes, transistors, and integrated circuits.


A diode is an electronic component that conducts electric current in only one direction. The most common function of a diode is to allow an electric current to pass in one direction (called the diode’s forward direction), while blocking current in the opposite direction (the reverse direction). Thus, the diode can be thought of as an electronic version of a check valve.

A modern semiconductor diode is made of a crystal of semiconductor usually p–n junction diode which is formed by joining P-type and N-type semiconductors together in very close contact.


A transistor is a semiconductor device used to amplify and switch electronic signals. It is made of three layer of semiconductor material, with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor’s terminals changes the current flowing through another pair of terminals. Because the controlled (output) power can be much more than the controlling (input) power, the transistor provides amplification of a signal.


It limits the amount of current that can flow, in a circuit and it protects from overload or to control the current in circuit. They are color-coded to indicate the intensity of resistance.

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