Why are they used?

Bipolar transitor (BJT) have two basic functions: "switching" (digital electronics) or "amplification" (analogue electronics). There are two basic types of bipolar transistor construction, PNP and NPN.

Applications / How do you spot opportunities?

Bipolar transitors was widely used in discrete circuit design. In analog circuits , transistors are used in amplifiers , audio amplifiers, radio frequency amplifiers, regulated power supplies , and SMPS. In digital circuits, they function similarly to electrical switches, and can used as a logic gates..

How to ask for opportunities?

Any Switching or Amplification function in your Circuit?