ROSE EDUCATIONAL AIDS: Electronics

BASICS OF ELECTRONICS COMPONENTS

Introduction

There are many basic electronic components that are used for making electronics circuits. The components include diodes, resistors, capacitors, transistors, PCB, integrated circuits, etc. These components consist of two or more terminals which are fixed and soldered on printed circuit boards to get electronic circuits. In this session we introduce some electronics components and simple working circuits in simple way with the help of images and diagram. This will guide you a basic level knowledge of simple hobby circuits and components

Diode

A semiconductor diode is a two terminal electronic component with a PN junction. It is a one way valve for electricity. A diode has low or zero resistance in one direction, and high or maximum resistance in the other direction.

Semiconductor Diode

The cathode is the negative terminal of a diode is represented with K and the anode, which is the positive terminal, is represented with A. To know the anode and cathode of a practical diode, a bar line is drawn on the diode which means cathode, while the other end represents anode.

Representation of anode and cathode of a practical diode

PN Junction

A p-n junction diode is two-terminal semiconductor device, that allows the electric current in only one direction but it blocks the electric current in opposite or reverse direction. When the diode is forward biased, it allows the electric current flow. If the diode is reverse biased, it blocks the electric current flow

Types of diode and application

Resistor

Resistor prevents the flow of electricity through a circuit. Resistors have a set value. It is a passive electrical component with the primary function to limit the flow of electric current.

Symbol of resistor

Classification of Resistors

Resistor series and parallel connection

Series circuits

Series circuit is a circuit in which resistors are arranged in a chain. The total resistance of the circuit is found by simply adding up the resistance values of the individual resistors.

If R₁, R₂, R₃are resistors connected in series then,

Total resistance, R = R₁ + R₂ + R₃

Parallel circuits

Parallel resistors are resistors that are connected across from each other in an electric circuit. See the picture below. In the picture below R1, R2, and R3 are connected in parallel to each other

Total resistance in parallel circuits, (1 / R) = (1 / R1) + (1 / R2) + (1 / R3)

Color code of resistor

Resistor Color coding uses color bands to easily identify a resistors resistive value with its percentage tolerance

The use of color code bands on the body of a resistor is the most common system for indicating the value of a resistor.

Each color band is associated with a numerical value.

To remember the number and color you can use this

BBROYGBVGW

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Types of resistors are
Linear

Ø Fixed resistor

· Carbon composition resistor

· Wire wound resistor

· Thick film resistor

· Thin film resistor

Ø Variable resistor

· Potentiometer

· Rheostat

· Trimmer

Non Linear

· Thermistor

· Photo resistor (LDR)

· Varistor resistor

Surface mount (SMD)

Capacitor

The capacitor is a component which has the ability to store energy in the form of an electrical charge producing a potential difference across its plates, much like a small rechargeable battery. It consists of two metal plates separated by a dielectric. The dielectric can be made of many insulating materials such as air, glass, paper, plastic etc.

A capacitor is capable of storing electrical charge and energy. The higher the value of capacitance, the higher the charge the capacitor can store.

BASIC CLASSICIFICATION OF CAPACITORS

v Film capacitor

Film Capacitor is one of the most popular and widely used capacitors. These possess a difference in the properties of dielectric. Film capacitors are made out of two pieces of plastic film covered with metallic electrodes wound into a cylindrical shaped winding in the terminals attached. In general film capacitors are not polarized. So the two terminals are interchangeable.

v Ceramic capacitor

Ceramic capacitors are the common types of capacitors used in most of the electrical instruments as they are more reliable and cheaper to manufacture.

These capacitors consist of ceramic or porcelain discs and are said to exist in a non-polarized form which is used in various types of industries. Ceramic material is known to be an excellent dielectric because of its poor conductivity. It is a fixed-value capacitor where the ceramic material acts as the dielectric. It is constructed of two or more alternating layers of ceramic and a metal layer acting as the electrodes. The composition of the ceramic material defines the electrical behavior and applications.

Electrolytic capacitor is a polarized capacitor whose positive plate is made of a metal that forms an insulating oxide layer through anodization. This oxide layer acts as the dielectric of the capacitor. Solid, liquid, or gel electrolyte covers the surface of this oxide layer serving as the cathode or negative plate of the capacitor. Due to their very thin dielectric oxide layer and enlarged anode surface, electrolytic capacitors have a much higher capacitance-voltage product per unit volume than ceramic capacitors or film capacitors.

v Super capacitor

Super capacitor is a type of capacitor that can stores large amount of energy. Generally 10 to 100 times more energy per unit mass or volume as compared to electrolytic capacitors. Super capacitor is also known as ultra capacitor or double-layer electrolytic capacitor.

Transistor

Transistor is a three terminal active device made from different semiconductor materials that can act as either an insulator or a conductor by the application of a small signal voltage. Transistor is a current driven semiconductor device which can be used to control the flow of electric current in which a small amount of current in the Base lead to controls a larger current between the Collector and Emitter. They can be used to amplify a weak signal, as an oscillator or as a switch. It is also known as a BJT (Bipolar Junction Transistor).

Transistors are hermetically sealed and encased in plastic or a metal components

Classification of Transistors

Inductor

Inductor is a coil, choke, or a reactor, is passive two-terminal electrical component that stores energy in a magnetic field when electric current flows through it. An inductor typically consists of an insulated wire wound into a coil around the core.

Integrated circuit (IC)

Integrated circuits are key components of modern electronics. They are the heart and brains of most circuits. Integrated circuit also called micro electronic circuit, microchip, or chip. It is an assembly of electronic components of resistors, transistors, capacitors, etc. All the components stuffed together into a tiny chip and connected together to achieve a special common goal. The individual circuit components are generally in microscopic size.