Transistors..

Hi Guys,

This time I have got a fairly famous analogy to share..the one used to explain the working of a transistor.

Transistors are quite famous. It can be thought as an electronic switch/amplifier. So what makes us dependant on transistors and why not those mechanical switches? Mechanical switches are at least easy to understand! The reason to this (and probably the only reason) is that these mechanical switches are bulky. Given the fact that we are moving towards miniaturisation, we badly needed a switch preferably manufactured using Silicon technologies. Transistors just did that! In fact, you might not realise as to how many transistors you deal with in your daily lives today. Also, you carry several thousands of transistors daily! (Mobile phones, Laptops,Mp3 players…) .  Would you not want to know what it is then? Nothing technical..just an analogy to help you correlate..! Keep reading..

Analogy:

Now, consider a large vessel housing a cork and another pipe inlet. If water is supplied to the mouth of the vessel (let us term this point as “COLLECTOR”), it might flow all the way down to the other end (“EMMITTER”). However, in the arrangement shown in the picture above, the cork blocks water to flow from the Collector to the Emitter. Well, then how does this water flow down? The pipe inlet (“BASE”) comes to the rescue here! If a sufficient amount of water is sent through the Base, into the vessel, the cork is slightly pushed upwards allowing the Emitter to receive (Collector water + Base water)! So in a nutshell, NO sufficient base water => NO Emitter water provided there is Collector water. Does this not itself seem like a switch? A switch controlled by the BASE? Maybe also an amplifier? EMITTER receives more than what was sent by the COLLECTOR..

There we go! You now know what happens in a transistor.. The Base, Emitter and Collector are the transistor pins. The collector is fed with the input current and the Emitter is the output. The Base current controls the switching operation!

Voltage, Current and Resistance?

Hey Folks. After quite lot of thinking, here I come up with yet another analogy. This time to relate to basic terms used in Electronics: Voltage, Current and Resistance. What are they really? How do I relate to it?   Keep reading...

Firstly, let me have for you their simple definitions.

Voltage is the potential difference between two points. That is if a point say "A" is at 15V and another point "B" is at 5V, then there is a +10V potential difference between points A and B. That is, Vab = 10V. Voltage is measured in Volts (V).

Current is the flow of electric charges through a certain medium normally due to voltage gradients (difference) between two points. In the above example, since there exists a voltage difference between points "A" and "B", electron flow occur from "B" to "A" (since "B" is more positive and electrons are negative charges). Remember that electron current travel in direction opposite to that of the electron flow and hence travel from "A" to "B". Current is denoted by symbol "I" and measured in Amperes.

Resistance is the degree or measure of obstruction that an object provides  to electric current when passing through it. Hence more the resistance of a medium, the lesser will it allow current to flow through. It is denoted by symbol "R".

Further, all these three parameters can be related to each other using a famous equation called the OHM'S LAW. The law states that, for an ideal conductor, V = I x R. This is not difficult keep in mind..    Higher the resistance => Less Current    Also Higher the resistance ==> Higher potential drop.

Well, I am sure you must be feeling quite dizzy by now! How do you remember/correlate these things? Below is my analogy..

I chose a see-saw to demonstrate since I am sure most of you at your early times would have used it for sure. Now, assume that Person1's weight is the voltage at point A and Person2's weight is the voltage at point B. If their weights are the same, the see-saw does not move. To see a see-saw in action (and thats the fun part), you need to have different weights.

The difference is weights can be thought as a difference in Voltage between those 2 points A and B and the motion of see-saw as the current flowing. The direction of motion of the see-saw will then indicate the direction of current (Higher weight to the lower one). However the motion of the see-saw is dependant on the pivot. The tighter it's screws are, the lesser it would move though you have got a differential weight. The pivot is the Resistance!

So, in summary here.. Voltages are analogous to weights of people, Current flow is analogous to movement of see-saw (direction too) & Resistance is analogous to the pivot holding the see-saw. As simple as it is!