Electronics Components

Electronics Components

Fig: Electronics components

 In this tutorial, we will be discussing Electronics Components, how they operate and their functions in the electric circuit. You can check out my previous post on Basic Concept of Electronics. 

Electronic components are the elements of  a circuit which helps in its functioning. They can be classified into two types: 

•  Active Components 
•  Passive Components

Active elements are those which possess gain and they can give energy to the circuit e.g. transistors, amplifiers etc.

On the contrary passive elements do not possess gain and they cannot give energy continuously to the circuit. e.g. resistor, inductor, capacitor .

RESISTORS:

Resistors are devices used in circuits to primarily limit current flow or to set voltage levels within circuits. Resistors are truly ubiquitous. There are almost as many types as there are applications. Resistors are used in amplifiers as loads for active devices, in bias networks, and as feedback elements. In combination with capacitors they establish time constants and act as filters. They are used to set operating currents and signal levels. Resistors are used in power circuits to reduce voltages by dissipating power, to measure currents, and to discharge capacitors after power is removed. They are used in precision circuits to establish currents, to provide accurate voltage ratios, and to set precise gain values. In logic circuits they act as bus and line terminators and as “pullup” and “pull-down” resistors. In high-voltage circuits they are used to measure voltages and to equalize leakage currents among diodes or capacitors connected in series. In radiofrequency (RF) circuits they set the bandwidth of resonant circuits, and they are even used as coil forms for inductors.

Symbol

Below are the schematic symbols of various kinds of resistors

Resistors typically come with resistance values from 1 Ω to 10,000,000 Ω.

Colour Coding

resistors generally have different resistant values known as the resistance, in order to make it very easy to identify the rated value or the resistance of any resistor we lay our hands on, manufactures makes us of a colour coding system to differentiate one resistor from another. The colours are divided into segments known as bands, some resistors have four bands while others have five bands. The images below gives  a clearer picture.

Fig A. Four Band Resistor chart (TOP)

            Five band resistor chart (bottom)

Fig B. Five Band Resistor chart

The above charts makes it very easy to determine the resistor's value.

 NB: If we have a 4-band resistor, the third band is the multiplier and the fourth band is the tolerance but in a 5-band resistor, the fourth is the multiplier while the fifth band is the tolerance

For example: The resistor in the image below has colour "brown" in its first band, colour "black" in its second band, colour "orange" in its third band and colour "gold" in its fourth band.

Using the colour coding chart in Fig A,  we would observe that colour brown has a value of  "1", colour black has a value of "0", colour orange which happens to be in the third band is the multiplier band and so from the chart we can see that we are to multiply by 1k which is "1000" and colour gold which is in the tolerance band  has a value of  "5%". We can now conclude that the above resistor is a 10,000 ohms resistor i.e. 10 x 1000 with  5% tolerance i.e. plus or minus 5%. So we have a 10,000 ohms resistor i.e. 10 kilo ohms (10k).

Other Examples:

Fig: 120 kilo ohms Resistor

Fig: 47 kilo ohms Resistor

Rarely do you see circuits that use a single resistor alone. Usually, resistors are found connected in a variety of ways. The two fundamental ways of connecting resistors :

• Series Connection 
• Parallel Connection

Series Connection

In series connection, same current flows through the network but different voltage drops across each resistor

The equivalent resistance in the series connection is given as:

  Rtotal = R1 + R2+ R3+ R4+.......+RN      

Parallel Connection

In parallel connection, same voltage drop is across each resistor but different current flows in each resistor in the network .

The equivalent resistance in the parallel connection is given as:

1/Rtotal = 1/R1 + 1/R2 + 1/R3+......+1/RN.

we will apply these formulas when designing circuits 

CAPACITORS     

These are components used to store electric energy in an electric field. If you take two oppositely

charged parallel conducting plates separated by a small distance apart by an insulator such as air or 

a dielectric such as ceramic you have created what’s called a capacitor.

DC current cannot flow through the capacitor as it blocks it allowing  a

voltage to be present across the plates in the form of an electrical charge due to

 this insulating layer.

Capacitors perform a number of functions in electronics some include:

• One major function is simple energy storage, where charge from an applied current is stored within the capacitor and later released back into the circuit as useful current. The rate of charging and discharging can be controlled by placing a resistor in series with the capacitor.
• The second major function of a capacitor when placed in series with a signal path is to block dc while allowing ac signal components to pass. A capacitor used in this way is referred to as a dc- blocking or ac- coupling capacitor. The second major function of a capacitor when placed in series with a signal path is to block dc while allowing ac signal components to pass. A capacitor used in this way is referred to as a dc- blocking or ac- coupling capacitor.
• Capacitors are also used to filter AC.

Capacitors are connected in two ways:

• Series Connection
• Parallel Connection

Series Connection

 

Parallel Connection

DIODES

A diode is defined as a two-terminal electronic component that only conducts current in one direction.

there are several types of diodes some include:

• photo diode
• Schottky Diode

• Zener diode  etc.

Applications:

• Rectifiers
• Clipper Circuits
• Clamping Circuits
• Reverse Current Protection Circuits
• In Logic Gates
• Voltage Multipliers

TRANSISTORS

A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power. It is composed of semiconductor material usually with at least three terminals for connection to an external circuit.

kinds:

• NPN transistors
• PNP transistors

Application

• Amplification 
• Switching

INDUCTORS:

An inductor, also called a coil, choke, or reactor, is a passive two-terminal electrical component that stores energy in a magnetic field.