Practical Electronics/Bipolar Transistors

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Transistors of different size


Transistor is made by joining one Positive Typed semiconductor in between two Negative Typed semiconductor or one Negative Typed semiconductor in between two Positive Typed semiconductor . The first is called NPN Transistor . The second is called PNP Transistor

All transistors have three terminals called (B)ase , (E)mitter, (C)ollector . Therefore transistor can be connected as two port network . Input port is at BE junction . Output is at CE junction . Hence, transistor is called Bipolar junction Device

Just like diode, Transistor needs to be biased to conduct or non conduct current to turn transistor on or turn transistor off. This makes transistor act like a Switch

Just like diode, Transistor allows current to flow in one direction when Transistor conducts current. NPN transistor pass positive half cycle . PNP transistor pass negative half cycle of signal

When transistor conducts current, it will act as voltage Amplifier either Inverting or Non-Inverting depend on the way resistors connect with transistor

Transistor's Types[edit]