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Construction of the both the transistors is simple by the way of doping we do. But the operation is quite confusing.
asked May 11, 2016 in Electro-Communication by T.PRATHIBA (181 points)
retagged May 12, 2016 by slow_learner | 88 views
+1 good question

1 Answer

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Best answer

BJT - Bipolar Junction Transistors , 

i.e Transistors with a junction of p-type and n-type semiconductors.

These BJ Transistors are used in :

  • Switches
  • Amplifiers or oscillators

Both PNP & NPN Transistors have same working principle but there are changes in :

  • How they are biased
  • Polarity of power supply

In simple words , in PNP transistors all voltages and current are reversed as when compared to NPN transistor.


NPN Transistor :

  • Current flows from Collector to Emitter
  • Electrons are important carriers

Uses:

  • Most common use of NPN is switches where it goes ON(Saturation Mode) and OFF(Cut off Mode) in high power devices

PNP Transistor :

  • Current flows from Emitter to Collector 
  • Hole (positively charged) are important carriers

Uses :
A PNP transistor in a radio boosts the relatively small signal from an antenna

answered May 12, 2016 by transformer (235 points)
selected May 12, 2016 by T.PRATHIBA
simple and clear answer. Thank you :)
its good to hear good comments..thanks