a laboratory course. We are living in an age of information technology. Electronics is

at the very foundation of information and computer age which we are living now presently.

The giant strides that we have made in the areas of communications and computers are

possible only because of the great successes that we have achieved in the field of electronics.

It is some times unbelievable how many electronics gadgets that we carry theses days in our person

for example digital wrist watch, calculator, cell phone, digital diary or a PDA, digital

camera or a video camera etc.

The different types of electronic equipments that have invaded our offices and homes theses

days are also mind boggling. Many things we use at home, offices are remote controlled.

For example television, air conditioners, audio equipment, telephone, we use a cordless

for example.

It is almost close to magic how even a small child now-a-days can switch channels or increase

or decrease the volume of sound in a TV at home by just clicking on a few buttons at

the comfort of a sofa away from the television apparently without any physical wiring or

connection.

Again we are astonished how we are able to talk to our near and dear living several thousands

of kilometers away from wherever we are at home, office, on the road in a car or in a

class room by just clicking on a few numbers on our palm sized cellular phones. Electronics

has thus made deep impact in several vital areas such as health care, medical diagnosis

and treatment, air and space travels and automobile. In short the technological developments of

several countries of the globe are directly related to their strengths in electronic design,

manufacture products and services related to electronics.

It appears as though that we have to add inevitably an "E" to the three "R's" that we

normally specify to declare a man and woman literate. That is the three R's are reading,

writing and arithmetic. Needless to add that the E I was referring to here means "Electronics".

So apart from reading, writing and arithmetic one should also have basic knowledge of E,

or electronics. Thus electronics has become surely a basic science and it is no more an

applied science.

Just as we teach physics, chemistry, biology and mathematics in our schools it is time

we start teaching our children at school electronics as a separate subject by itself. This brings

us face to face an important question how to teach the basic concepts of such an important

subject like electronics in a most efficient and effective manor. If one wants to gain

a good grip and understanding of electronics he or she should build circuits and test them

independently.

For this one should acquire a practical knowledge of the characteristics of different devices

and in constructing the various circuits let as try to learn such skills by the proven

scheme of "learning by doing".What is this? An old Chinese proverb says I read -- I

forget; I see-I remember; I do-I understand. So if you need to understand and apply whatever

knowledge you acquire then it has to be by the method of doing rather than reading or

seeing. There is only way to learn to do anything; that is just do it. That is the way we all

have learnt as a child even to talk, to walk, to ride a cycle or whatever.

Many arts and special skills like dancing, singing, swimming and martial arts are all

learnt by going to an expert or a teacher who makes us learn by doing rather than by

listening to lectures or reading books. But why "learning by doing" is so important?

It is very simple. The reason is while doing we are given an opportunity to fail. So failures

are very important in the learning process. Nobody wants fail and if one fails, one starts

wondering as to what went wrong. Thus at the point of failure there is a profound learning

taking place. That is why people say failures are stepping stones to success.

Before we go into the subject of electronics it will be nice to look at some of the historical

background of electronics. I will just mention to you few landmarks in the history of electronics.

The invention of vacuum tubes or the thermionic valve brought in the age of electronics long

time back. Many new and exciting applications were found for theses devices. Many great

names like Edison, Marconi, Ambrose Fleming, De Forest, etc., are associated with electronics.

As a mater of fact the transition from the diode to the triode which has got three electrodes

was brought about by engineer suggestion by deforest. He suggested that we can introduce

a third electrode in the vacuum tube diode to make it into a triode and that really brought

about a major change and development in the area of electronics. You can see some examples

of vacuum tube on the screen.

These are different types of vacuum tube used in those days for amplification purposes and

things like that. You can see they have a filament, which is a thermionic filament.

When I pass a current through that thermionic electrons are develop which are collected

by an electrode, called the plate and you have another electrode the third electrode

which is the control grid which is in between these two electrodes and any voltage impinched

on them will alter the flow of electrons between the two main electrodes- the cathode and the

anode. So that is responsible for the amplification and such things. After the war in 1948, the

transistors were invented in the Bell laboratories in the USA by the three great people Bardeen,

Bratain and Shockely and that brought in much greater miniaturization and applications in

the area of radio electronics and things like that.

On the screen you can see some of the examples of transistors, different types of transistor

are shown in the photographs and the major development in electronics came up with the

introduction of integrated circuits. This invention is one of the major developments

in the area of electronics.

Here transistor have become already common place in everything from radios to phones

to computer and therefore the manufactures wanted some thing even better, some thing

which is much smaller and much more powerful. Two people are associated with invention of

integrated circuits. They are Jack Kilby of Texas instruments and Robert Noyce of Fairchild

semiconductors and Jack Kilby were awarded the noble prize in 2000 for his development

of integrated circuit. Robert Noyce was no more at that time and therefore Jack Kilby

alone was given for the partial development of the integrated circuit ideas.

Integrated circuits can be now found in almost every modern electrical device such as computers,

cars, television sets, CD players, cellular phones, etc. I will show you some photographs

of that. The basic idea here is the semiconductors are used for preparing the transistors. But

other devices like the resistors and capacitors have to be independently made by discrete

methods. It was the idea of Jack Kilby and Noyce whether the same semiconductors can

be used to also prepare diodes, resistors and capacitors.

Resistors can easily be developed by doping the semiconductor suitably and the capacitors

can be developed by using a p-n junction diode in a reverse bios mode and therefore diodes

can be made; resistors can be made; capacitors can be made out of semiconductor therefore

Jack Kilby and others started to make the whole circuit, which involves different devices,

completely using semiconductors. That is how the whole idea of integrated circuits came.

You integrate the different components like transistors, diodes, resistors and capacitors

all made of basic semiconductor material on the same substrate. The bulk resistivity of

the semiconductor and its diffusion doped layers could be exploited for fabricating

resistors, p-n junctions, diode, etc., and that I already mentioned. So this is one of

the fast integrated circuit idea which was implemented by Jack Kilby in his lab. You

can see that it is very crude and it has got no resemblance to the modern, well refined,

design of integrated circuit which I will show you in the next graph.

One of the integrated circuits with its memory chip is shown here and the other picture here

shows different integrated circuits. They have different packages. In all of these you

can see enormous number of transistors being prepared side by side and few of resistors

and very few capacitors and no inductances at all.

So integrated circuits are characterized by very many numbers of transistors, few resistors,

very few capacitors and almost no inductances. Therefore the whole idea of integrated circuits

completely modified the concept of circuit design. Instead of going for the distribution

of various devices, in olden days circuits will have more of resistors, capacitors, etc.,

and less number of active devices like transistors but with the introduction of integrated circuits

the situation reversed. That is we have more number of active devices like transistors,

etc and less number of resistors, capacitors and things like that. So this is generally

the background of the brief history of the electronics. Now I will move over to the table

to show you some real transistors, vacuum tubes and integrated circuits.

Here you can see the vacuum tubes. This is a vacuum tube which is used for power electronics.

You have number of pins; you will have a base into which these pins will go and the corresponding

voltages will be applied.

These are characterized by very high voltages of the order of 200-300 volts and you require

a separate power supply for energizing the filament and therefore you require large number

of power supplies and they will dissipate enormous amount of energy and therefore you

will find that they have to be cool if large big circuit are built with vacuum tube diodes

and triodes you require very efficient cooling system. Whereas when you come to the transistors,

these are semiconductor transistors. You can see this is smallest one; very small three

terminal device just as you have triode where you have plate, control grid and cathode,

here you have three electrodes -- emitter, the collector and the base. Here again you

have a slightly bigger one; this is for higher current or higher power. This one is much

higher power and this one very large power of several watts. I will just perhaps take

it out and show it you. You have two terminals only here. They correspond to the emitter

and base and the casing becomes by itself one of the other electrodes which is the collector

which takes the brunt of current in any given circuit. So these are transistors of different

type, all made of semiconductors.

Then we come to the integrated circuits. You have here a very tiny one which has got eight

pins on either side. These are called dual in line package and you have much larger one

slightly larger one which has got fourteen or sixteen pins on either side; eight on either

side or seven on either side. This one is the much larger integrated circuit which has

got about forty pins; twenty on one side and twenty on the other. So these are integrated

circuits which have got several transistors.

For example this will have easily about twenty transistors; this will be much larger and

this will have thousands of transistors inside and the actual semiconductors will be some

where very small, few millimeter squared and to make them easy to handle they are put on

bigger package with number of pins so that they can be connected into a real circuit

outside.

So these three are the modern integrated circuits. The latest integrated circuits in the computer

that you see will have much larger number of pins of the order of 396, 400 and things

like that and some of resistors, capacitors also have to be used along with these for

building different circuits which have come in; something very similar to intergraded

circuits and are called surface mountable devices. So along with these things the miniaturization

is complete. Therefore you have enormous number of applications coming out of them including

the things that you know of like the cell phone and things like that. They have enormous

number of very tiny circuits built with several integrated circuit and several small devices

like transistors, capacitors, resistors, etc all found in one. They are all wired on one

single printed circuit board; the circuit board itself will be printed with the all

the wiring pattern and the whole thing in modern times is all automated and therefore

large number of such things can be manufactured very quickly and very efficiently and these

devices they also increase in the order of efficiency and performance. The vacuum tubes

are not all that good because they have enormous amount of heat generated. These are good but

these are much better. Here the transistors are very close to each other and therefore

the performance and reliability is enormously improved in these integrated circuits

Now let us see what we will discuss in this course on basic electronics. We have components

and devices which go into the building of circuits; we have measuring instruments like

different types and we also have circuits to learn. For example if we take the components

and devices you can classify them basically into two; one is called passive component

devices. The examples of passive components are resistors, capacitors, diodes, inductors,

etc. If you look at active components there are transistors, operational amplifiers, etc.

The passive components cannot amplify; they will only attenuate. If a signal or voltage

or current is given to them there will only be reductions if at all after passing through

this component. Therefore they are called passive. Whereas if you take the active components

like transistors or op amp, there can be an enhancement of the voltage or current or whatever

and therefore they are called active components.

Now if we look at measuring instruments one has to know something about the digital multimeters.

Most of them are digital multimeters. There are a very few occasions when you come across

analog multimeters. Power supply is very essential for the powering the different circuit for

working; voltage sources and current sources, oscilloscopes for observing the different

wave forms and function generators which are basically to generate different kinds of wave

forms or signals. When you come to the circuit, you find different types of circuit like rectifiers,

amplifiers, oscillators, filters and so many different types of circuits.

What is the prerequisite of this course? The basics prerequisite we assume for this is

that you have a general understanding of the principles of electricity and magnetism. That

is all that is required to know from your side. Once you know that we will be able to