BASIC CONCEPTS� OF �ELECTRONICS

PRESENTED

BY

DEPARTMENT OF ELECTRONICS

TJPS COLLEGE,GUNTUR.

​

Electronics is the branch of science that deals with flow, control of electrons and also specify their behavior and effects in vacuums, gases & semiconductors.

Passive Components:

Components which do not required external source to their operation is called Passive Components. ��

Active Components:�Components which required external source to their operation is called Active Components.

Electric Current

​

Definition: The continuous flow of electrons in an electric circuit is called an electric current.

​

 Unit of Current:

​

The charge is measured in coulombs and time in seconds, so the unit of electric current is coulomb/Sec (C/s) or amperes (A).

The amperes is the SI unit of the conductor. The I is the symbolic representation of the current.

Mathematically, it is represented by

RESISTOR

​

Resist is the word which means “to oppose”.

​

 Resistance is the property of opposing the flow of electrons, in a conductor or a semiconductor.

A Resistor is an electronic component which has the property of resistance.

Symbol and Units

The symbol for a Resistor is as shown below.

​

​

​

The units of resistance is Ohms, which is indicated by Ω omega.

The formula for resistance is

R = V/I

​

Where V is Voltage,R is Resistance and I is Current.

• Indication − R
• Units − Ohms
• Symbol − Ω

​

Color Coding

The below table shows a list of values which each color indicates.

​

Example 1 − Determine the value of a resistor with a color code yellow, blue, orange and silver.

​

Solution − The value of yellow is 4,

blue is 6, orange is 3 which represents

multiplier.

Silver is ±10 which is the tolerance value.

Hence the value of the resistor is

46×10³ = 46kΩ±10

.

Ohms Law and Power:

​

The relationship between Voltage,

Current and Resistance in any

DC electrical circuit

was firstly discovered by

the German physicist Georg Ohm.

​

Georg Ohm found that, ��1.At a constant temperature, the electrical current(I) is flowing through a fixed linear resistance(R) is directly proportional to the voltage(V) applied across it.� i.e., I α V��2. it is inversely proportional to the resistance(R).� i.e., I α 1/R� This relationship between the Voltage, Current and Resistance forms the basis of Ohms Law and is shown below.

Ohms Law Relationship

​

By knowing any two values of the Voltage, Current or Resistance quantities we can use Ohms Law to find the third missing value. 

​

Ohms Law is used extensively in electronics formulas and calculations so it is “very important to understand and accurately remember these formulas”.

To find the Voltage, ( V ):

​

[ V = I x R ]      V (volts) = I (amps) x R (Ω)

​

To find the Current, ( I ):

​

[ I = V ÷ R ]      I (amps) = V (volts) ÷ R (Ω)

​

To find the Resistance, ( R ):

​

[ R = V ÷ I ]      R (Ω) = V (volts) ÷ I (amps)

Ohms Law Triangle:

​

CAPACITOR

​

A Capacitor is a passive component that has the ability to store the charge(or) energy in the form of potential difference between its plates.

.

• A capacitor consists of two parallel plates separated by a dielectric.

​

• The dielectric can be made of many insulating materials such as air, glass, paper, plastic etc.

​

• The symbol for electrical charge is Q and its unit is the Coulomb.

​

• Electrolytic capacitors are polarized. They have a +ve and a -ve terminal.

​

• Capacitance is measured in Farads, which is a very large unit

​

• so micro-Farad ( μF ), nano-Farad ( nF ) and pico-Farad ( pF ) are generally used.

Inductor

Inductor is a passive two-terminal component that temporarily stores energy in the form of a magnetic field.

​

It is usually called as a coil.

​

The main property of an inductor is that it opposes any change in current.

Diode.

A semiconductor diode is a two terminal electronic component with a PN junction. This is also called as a Rectifier.

​

​

Formation of a Diode:

​

​

​

​

​

​

​

​

​

​

​

​

​

A P-type material has holes as the majority carriers and an N-type material has electrons as the majority carriers.

Biasing of a Diode:

​

A diode has two biased conditions with the given supply. They are Forward biased condition and Reverse biased condition.

​

Forward Biased Condition:

​

When a diode is connected in a circuit, with its anode to the positive terminal and cathode to the negative terminal of the supply, then such a connection is said to be forward biased condition.

A diode conducts well in forward biased condition.

Reverse Biased Condition:

​

When a diode is connected in a circuit, with its anode to the negative terminal and cathode to the positive terminal of the supply, then such a connection is said to be Reverse biased condition.

​

A diode cannot conduct in reverse biased condition.

 Transistor

​

A Transistor is a three terminal semiconductor device that regulates current or voltage flow and acts as a switch for signals.

​

A transistor also acts as a switch .

​

It also regulates the incoming current and voltage of the signals.

Construction of a Transistor:

​

The Transistor is a three terminal semiconductor device which is formed by connecting two diodes back to back.

​

Hence it has got two PN junctions.

​

​

​

​

​

​

Emitter

​

• The left hand side of the above shown structure can be understood as Emitter.

​

• This is  a heavily doped as its main function is to supply a number of majority carriers, i.e. either electrons or holes.

​

• As this emits electrons, it is called as an Emitter.

​

• This is simply indicated with the letter E.

Base

• The middle material in the above figure is the Base.

​

• This is thin and lightly doped.

​

• Its main function is to pass the majority carriers from the emitter to the collector.

​

• This is indicated by the letter B.

Collector

​

• The right side material in the above figure can be understood as a Collector.

​

• Its name implies its function of collecting the carriers.

​

• This is a bit larger in size than emitter and base. It is moderately doped.

​

• This is indicated by the letter C.

​

The symbols of PNP and NPN transistors are .

The arrow-head  indicated the emitter of a transistor.

Advantages

​

There are many advantages of a transistor as

​

• High voltage gain.

​

• Lower supply voltage is sufficient.

​

• Most suitable for low power applications.

​

• Smaller and lighter in weight.

​

• Very suitable to integrate with resistors and diodes to produce ICs.

​

​

Light Emitting Diode (LED)

​

It is most widely used semiconductor which emit either visible light or invisible infrared light when forward biased.

​

Remote controls generate invisible light.

​

A Light emitting diodes (LED) is an optical electrical energy into light energy when voltage is applied.

Layers of LED

​

There are three layers in a light emitting mode (LED). These are:

​

P-type semiconductor

Trivalent impurities are added to the intrinsic or pure semiconductor. Holes are majority charge carriers.

​

N-types semiconductor

Pentavalent impurities are added to the intrinsic semiconductor. Free electrons are majority charge carriers.

Working of LED

​

Light Emitting Diode (LED) works only in forward biased condition

where free electrons are from n-side and the holes from p-side are pushed towards the junction.

​

The recombination of free electrons and holes takes place in depletion region as well as in p-type and n-type semiconductor.

​

Hence each recombination of charge emits energy in the form of light.

Types of LED:

​

These are various types of light emitting diodes:

• Gallium Arsenide (GaAs) – infrared
• Gallium Arsenide Phosphide (GaAsP) – red to infrared, orange
• Aluminium Gallium Arsenide Phosphide (AlGaAsP) – high-brightness red, orange-red, orange, and yellow
• Gallium Phosphide (GaP) – red, yellow and green
• Aluminium Gallium Phosphide (AlGaP) – green
• Gallium Nitride (GaN) – green, emerald green
• Gallium Indium Nitride (GaInN) – near ultraviolet, bluish-green and blue
• Silicon Carbide (SiC) – blue as a substrate
• Zinc Selenide (ZnSe) – blue

​

​

Advantages of LED:

​

• Brightness of LED can be easily controlled by varying the current.

​

• These are smaller in size, light in weight and have longer in lifetime.

​

• LEDs operate very fast.

​

• These can emit different colors of light.

​

Disadvantages of LED:

​

Main disadvantages of LEDs are efficiency is low and need more power to operate than normal p-n junction diodes.

​

Applications of LED:

​

These are various applications of LEDs:

• Digital computers and calculators
• Traffic signals and Burglar alarms systems
• digital watches
• Camera flashes and automotive heat lamps

​

Breadboard