Understanding Operational Amplifier - OpAmp

This article will not discuss about the mathematical interpretation of OpAmp. Rather, it'll be talking about why we use OpAmp or Why is OpAmp so important? So, if this is the night before your exam, I cannot help you. But, if you are working on your first OpAmp based project, continue reading.

Figure: Typical OpAmp Symbol

How does OpAmp work?

Truth is, I don't know. All I know is there are at-least 13 transistor inside an OpAmp and together, they do magic. In the past, there has been a lot of research on how to make OpAmp more efficient and useful. So, if we are to understand the exact working procedure of OpAmp, it'll take a lot of study. Even today, I have no clue how an OpAmp function internally, although I've done numerous projects with it. So today, I'm going to talk about OpAmp from application point of view.

OpAmp has 3 basic functions:

1. Amplifier
2. Comparator
3. Buffer

Figure: 'Inverting' Amplifier

If you connect the output and the input of an OpAmp through a resistor, it'll function as an amplifier. Depending on your connection, it can be either an 'inverting amplifier' or an 'non-inverting amplifier'. Whatever it is, it is basically the same. It'll amplify your input signal. I find it easy to use OpAmp as an amplifier. It is less hassle than to design an amplifier using transistor alone. 

Figure: OpAmp as 'Comparator'

If the output and input are not connected, then the OpAmp will function as a comparator. It is another very useful application. It allows you to compare an unknown voltage against a know voltage. Using multiple OpAmp and multiple known voltage reference, you can even design a low quality digital multimeter. You can make a line follower Robot using only comparators.

Figure: 'Buffer Ic'

If you connect the output and the input with a wire, it becomes a buffer IC. You can also call it a power amplifier. It means, output voltage will be same as input, but you can amplify the current. Hence drive a power hungry device, such as, a motor. 

OpAmp are also used where some sort of electrical isolation is required between two devices. Output pin's voltage and current depends on the biasing voltage of OpAmp. So whatever load is connected to output pin of OpAmp, it draws power from the same source as the OpAmp, not from the device which acts input to the OpAmp. 

My insight:

You all know, the age of personal computer began after the invention of transistors. A microprocessor will do anything you program it to do. OpAmp is basically a collection of transistors. Therefore, any program you write on a microprocessor or a micro controller (say operating a robot), same function can be implemented by OpAmp alone. Of course, the circuit will be enormous. But it's possible. 

In general, OpAmp decreases the difficulty of putting together multiple elements in a circuit. Same IC can perform a different task only by changing it's external connections.

In any semiconductor book, you'll find OpAmp appears before MOSFET and transistor. Technically, operation of MOSFET and transistors are easier to understand and OpAmp is a complex arrangement of transistors. So why introduce OpAmp first? Well, this is mainly because, in professional world, we are most likely to use OpAmp for amplification / comparison purpose. Other uses of transistors are easy to understand and it's function are limited. Furthermore, OpAmp are much more fun to work with. So don't worry about OpAmp's related equation first. Play with it. Get to know OpAmp. Then you'll have fun time reading about the mathematical explanations.

Figure: Internal circuit of an OpAmp

To know the full working procedure of OpAmp, you can refer to research papers anytime. Or look up on the Internet for some information enrich articles. But be warned, many of those information are result of years of research. So, for obvious reason you might not understand it in one day. But don't give up. Keep reading them. Study EEE hardier. And one day, help me understand OpAmp better!

Surviving life...!!!

Have we been blinded by our greed so much that we have forgotten how beautiful our life is?

Now a days, I often find myself asking, What am I actually doing? What I need to do and Where my life is heading to?

Life in our time has become so much of routine work, that we have learned to turn a blind eye to what actually matters.

You'll see successful businessmen, making tons of money but has no time to spend with his family.
You'll see brilliant mathematician, working as a cashier at some bank.
You'll see dumb kids at universities, just because they need a degree to hang on their wall.

WTF if wrong with us?

Workaholic - A Short story

[Note: This is my first take at fiction writing. Not to be mixed with my regular articles. ~Maisun]



"Will you have your usual menu, Ishraque?"

"Absolutely."

"How's that neck pain today?" Said Erik while serving the dishes.

"It's better today. I barely remember about it. I'm having such a busy time with this new project."

"Let me guess, you'll have to kill me if you told me."

"Correct. I can't possibly tell you how this new machine of mine will replace traditional medicine manufacturing and produce huge batch of life saving medicine within days."

"Enjoy your meal. See you in a bit." smiling as he went to sever other in the cafe.

Not that he was hungry. But his life has become more of a clock work now a days. Not that he needs the money, he has plenty of it. Nobody knows how much money he has. Once in a while, he would go to his bank and write of huge checks to charity in Africa. Not the ones who provide food, but education. He never explained why he does that. If you asked me, some of the people there could use little more food. You can't focus on learning when you are hungry. Unless the books are edible.

Global conflicts, deforestation, hunger, riots, war are the least of his worries. Hell, he doesn't even know the name of current President of USA. He is an workaholic. Only thing he thinks about, is his work. It changes time to time. But remains in the same genre.

" May be I should re-calibrate the speed of the ....."

His chain of thoughts was broken by a mild voice, "Is this seat taken?"

"No". He didn't even look up. In this cafe, he always took the seat in the corner. He would always seat with his back to the streets and facing the park. Not that there was a lot to see, it was quiet. No one bothered him here.


"Don't you get bored eating the same food everyday?"

For an unknown reason he would eat the same food every lunch hour. Sometimes the menu is different. But usually, it's the same. Erik knows about it. That's why he never goes into the details. Little rice. vegetables, preferably green, well cooked but not overdone. A big chunk of chicken or sometimes sea fish, of course the season has to be right.

Besides Erik, the cafe manager knows this. On busy day he would keep the bill ready ahead of time. Ishraque is not a man who likes to waste his time. And the cook knows it too. How would he forget? He nearly lost his steady pay check when he mistakenly overcooked the vegs. Nobody else supposed to know about his food habits.

Curious, he looked up.


"You haven't changed." said the lady, putting down his laptop on the table.

"I can say the same about you. You look old, but your smile is the same." said Ishraque after a long pause.

"What are you upto these days?"

"Not much. I work for agencies. Picking up a project or two."

"Aren't you gonna ask me how I'm doing or where I was all these time?" Said Jerin breaking the long silence.

"I would, but why ask question when you already know the answer to?" Trying to focus on his meal. On any other day, he would have finished by now.

"Still haven't gave up that 'Mr. Know-it-all' attitude? I'm impressed." now her eyes on the laptop screen.

"In my line of business, you get used to it."

"I do have to tell you, I could never predict you becoming a reporter." eating up the very last bit of his meal as slow as you possibly can.

"Thank you. I'll take that as a compliment" said Jerin as she ordered herself a cup of coffee.

"If I were you, I would have pressed charges against that Restaurant owner. You had every rights to say what you said."

"There was no need. He suddenly backed off after 2 days."

"Guess he wasn't so dumb after all." A little smile on Ishraque's face.


"Guess I'll be seeing you around." said Jerin as Ishraque was getting up from his chair.

"No you won't." said Ishraque as he put on his coat and moves towards the exit.



Why does he work so hard? Nobody knows. He would probably have to kill you if he told you.


~Maisun.
[Note: This is my first take at fiction writing. Not to be mixed with my regular articles. ]

Robotics: Where do we stand?

Working with robotics doesn't always refer to big and heavy piece of metal moving on its own, doing works with great efficiency previously done by humans. In the developed part of world, robotics is a hobby, an art form to many. In Bangladesh, its a challenge.

Robotics is a challenge not because it takes patience and hard work to complete, it is challenging because we live in Bangladesh.

It pains me to say it, but I find it the main reason.

I wish it wasn't true. I really do.

Resources are extremely limited when you are in Bangladesh and working on robotics. Building a project takes money, usually from your own pocket money. Even if you have sufficient funding, local electronics store may not have what you need. Sometimes we need to wait 3+ months to get a single IC. That too, from China with no guarantee of product and almost with no documentation. If you get through these two obstructions, you may then proceed to learn/build robotics. How long can you keep it up? Until you are a under-grad student. Soon as you graduate, you need to find an 'Actual' job. Otherwise, the society points finger at you. if not, the praise you in the beginning and then ditch you. They always do. Few find the courage and will power to carry on with their passion and works in Electronics/Robotics. Only FEW.

I recently met with a junior at my University. His father is an EEE and an entrepreneur. He's been building, testing and selling various items for a long time. Learning that he owns a CNC routing machine (I never knew there was one in Bangladesh) I was eager to meet him; and I did. Once a glorified Engineer and manufacturer, now does simple import and export business. He had so much to offer this country hadn't there been uncontrolled imports from China. I'm no economist, but I feel poor quality and uncontrolled imports from China has choked our domestic economy.

There is no significant industry in Bangladesh. Hence, Engineers find themselves behind a desk, filling routine paper works or in banks, counting others money.

Despite all of these nuisance, some managed to survive and held their heads high. Jonayet vaia for example. He has managed to build "ChondroBot" literally out of scraps. I have only heard of stories of scavenge hunt for suitable motor in Dholaikhal and the world has witnessed and group of undergrad students from a third world country make their way to 12th place worldwide in LMC 2012.

I've been assured by Kafi vai, that there are places in Bangladesh where Engineers solve actual problem s; whereas their batch mates are pushing papers from one desk to another. I have been informed by Promon, that there lies a group within Bangladesh which actually works on robotics. I've seen Shams waking up and doing something about his dreams. I've been told by Ron vai, hope is still there.


You know what I believe? I believe all great things starts with a dream.




It was 20th of February, about 2130 hrs. After having a closer look at the CNC machine, dust covered transformer winding machine, rusting transistors and innumerable boxes of unsold products; when uncle was about leave his office, I asked him, "Uncle, do you have any plans for comeback in future?"

He said, "No. I no longer have the energy." There was no dream in his eyes.

Now the question is, what becomes of us?

Probability, Practicality and Feasibility

I don't know if I've taken my studies a bit too seriously, but I know one thing for sure, I'm obsessed with 'practicality', 'probability', 'feasibility', 'efficiency'. If something is not "Mathematical", I lose my cool temper.

I'm not quite complaining about 'uncertainty' of life. I would rather say, I got to understand the beauty of it. The beauty of uncertainty, a momentary chaos; can sometimes be beautiful. If luck favours, you get to smile. If not, you get a set of problems to work on.

For me, it was a good day.

Surviving Quantum Entanglement...

At one hand side, you have logic. Solid, mathematical and objective. You know what you have done, doing or have to do. There's no denying of logic. Specially when you a student of science.

On the other hand, you have emotions. Abstract, conscience and mysterious. Sometimes, we call it instinct. We just know it is right, but have no proof of it. Most people didn't need any. Expect those, who fail to find the bridge between them.

I used to be one of those people in the later group. Scared of the logical outcome, refusing to take a leap of faith. Trusting my logic and logic only. Trying to deny the existence of instinct.....blindly.


At  the end of the day, I'm only a human being.



Praise to the Almighty, by whose grace I've found the missing key. The bridge between logic and instinct (read that as emotion). Ying and Yang. Harmony...Inner peace. I would also like to thank the people who have supported me so far. And a special credit goes to Larry Fleinhardt. With out his lecture Quantum Entanglement, this revelation would have been much more delayed.



Maisun Ibn Monowar.
7th December, 2013. 0215 hrs.
Original Article: "December 7th"

Surviving Over-Sharing

Hard to believe, but it is the truth. Social networks have made us socially isolated. Your world gets only smaller when you are a social network addict. Continuously making calculation of what others have and what you need, overlooking the most important calculation of all, what valuables do you already have.

In my opinion over-sharing can be rightfully tagged a mental disorder. And it seems, I have that disease.