Transistor is a basis building of a modern electronics . Without transistor no electronics device can be made .As the name suggest transistor is nothing but a transformative resistor which transform voltage and current in one form to another ie with the help of transistor we can either increase the level of current or voltage or decrease it.With the combination of transistor capacitor re
sistor we can make different logic gates , processing circuits and many more in the field of digital and analog electronics . If you have good concept of transistor you can make your own logic circuit .As said above transistor is resistor but it is a non linear resistor . If you plot a voltage versus current graph for different value of resistor the graph is linear because the relation ship between voltage,current,resistor is resistor=voltage x current . Since transistor is a non linear device it doesnot follows this simple ohms law of resistor.In transistor if we plot current versus voltage graph there is a non linear characteristic curve which is exponential in nature . So a little bit of knowledge is required to make a circuit using transistor .
Basic principle of Transistor and how it works
There are two kind of transistors PNP and NPN according to the doping method of P-type material and N-type material. But if you understood one you can easily understand another . Here is the video demonstration of Transistor have a look and try to understand its principle