Tag Archives: Transistor

Building Circuits from Scratch

This is all about “Do It Yourself: Electronics”, as how it started between two college friends from NIT Warangal.

“Oh! It was a total tangential lecture today”, sighed Pugs in the cafeteria.

“Why? What happened Pugs? What was it about?”, asked Surya.

“Electronics Fundamentals, yaar”, replied Pugs.

“But, why in this world have you chosen that elective, you being a comps guy?”, asked Surya with curiosity.

“I wish to design some electronic circuits of my own. So thought, that might be helpful.”

“That sounds interesting. But I can understand, what would you have felt in the lecture. BTW, what was the topic today?”

“Don’t ask me yaar. All these electrons moving around, then these imaginary holes, the potential barriers, and what not. After initial 5 minutes, I was totally lost.”

“You know what? You don’t really need to know all these gory details to design basic electronic circuits. And moreover, you should go by the top-down approach to fulfill your wish.”

“O really! And what is this top-down approach”, exclaimed Pugs.

“What I mean is that you should first start playing with the various electronics components, understand their practical usages by designing simple breadboard circuits. And, then go into the gory details, if necessary”, explained Surya.

“That’s wonderful. Design the circuits first. Cool!! … But how do I start? I don’t have any clue about what components, etc”

“That’s easy. I can give you a practical hands-on kick-starter.”

“That’s great Surya. I hope after that I’d be able to start designing circuits, and may be able to make sense out of the lectures, as well.”

“Ya sure Pugs. Let’s go to my room. I have various electronics stuff there to get you started.”

“Just an idea. I know, I am going to get an amazing kick-starter, and there may be many more like me. So, why not record your kick-starter.”

“Hey! No yaar. It is just for you”, Surya replied shyly, thinking of the public exposure.

“Come on Surya. Think of it. Your knowledge sharing could benefit so many.”

“Hmmm!! …”

“Don’t think so much. I know that would thrill you. Let me get the photography club guys to film it.”

All set in Surya’s room, he took out his various electronics stuff, and started explaining them to Pugs, as follows:

Pugs was all excited after this first level of kick-starter by Surya, and requested Surya to show the video on resistor colour coding, as well.

Here is what Surya showed on his laptop:

“I understood what all you showed me. But how do I use the various things?”, queried Pugs. “Okay. So, I’ll now show you the simplest electronics circuit – ‘Blinking an LED'”, replied Surya. And, here is what he did:

“That was really simple. Something like the ‘Hello World’ program we write, when we start learning a programming language”, expressed Pugs. “Exactly, that’s what it is in the electronics world – blinking an LED”, confirmed Surya.

“Chalo Pugs, let’s go for lunch”, said Surya, trying to shutdown his laptop. Pugs interrupted, “Ay no Surya. Just before we go for lunch, I have a small doubt”. “Ya, tell me”, asked Surya. “Theoretically, you explained to me about the various current, voltage, resistor values from the datasheets etc, and then built the circuit. Do this circuit, really have those values?”, doubted Pugs. “What do you think?” asked Surya. “If you are asking means should be, otherwise how would the circuit work.”, Pugs tried to confirm with Surya. “Yes and No. They would be close to those values but not exact – and that is what is practical about it – to be tolerant about the tolerances. To drive the point home, I think, let me show you the actual readings using a Digital MultiMeter (DMM)”. And with that, Surya demonstrated the following measurements:

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