Firstly thanks for such a beautiful query.
Before coming to your query… I want to give you a feel of Transistor with the help of some real world concrete examples. [Try to maintain some patience for further discussion and ignore some technical points for simplicity]
Image - 1
Any physical system in this physical world is expressed physically in a simplest form, with some Input ‘X’, some Output ‘Y’ and main block (like this).
Image - 2
In our daily life this example, we have seen very frequently. And we are quite familiar with the use of each and every unit of our Electric Fan System.
In this picture,
Input ‘X’ = Switch
Output ‘Y’ = Air (by rotation of fan)
‘Z’ = …?
Image - 3
Its a domestic Electric Juicer Machine, similarly here also
Input ‘X’ = Fruits feeding
Output ‘Y’ = Juice
‘Z’ = …?
In above all examples some common entries are,
- input (X)
- output (Y)
- and, one additional variable ‘Z’.
In case of fan, this ‘Z’ is a simple regulator who control the speed of fan (based on our requirement) whereas for juicer it's a knob who control the speed of motor (again based on our need).
Finally… this ‘Z’ variable is nothing but a controlling agent who control our process based on our requirement.
Now come to your Point of Interest(POI)…
- In every system (including electronic) controlling is a most important part to run our system efficiently. Since for controlling capability, a system must have (minimum) 3-port i.e terminal. Out of which one terminal (here X) for input, one for output (here Y) and one terminal for control input (here Z).
Since Diodes having only 2-terminal means no controlling action possible whereas Transistors (BJT, FET’s e.t.c) is A three terminal device.
Thus configuration of transistors allows for controlling action due to presence of controll terminal (i.e for BJT ‘Z’ is Base and for FET’s ‘Z’ is Gate terminal).
So just because of these unique controlling action capability; transistors covered more space in our academic-syllabus.
Technically in our electronics world the major functions of transistors are
- switching action i.e as a switch (what I have discussed in above examples)
- amplification action i.e as a amplifier
Thanks for your patience.
Hope it’ll help you!
-JP.
If you're a hard core e-lover must be greatful to Bell-Lab and American Physicist John Bardeen, Walter Brattain, and William Shockley, who invented (1947) this magical device.
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