Transistor Circuit Symbols

There are not too many circuit symbols for bipolar transistors. There are of course different circuit symbols to indicate NPN and PNP transistors.

In addition to this, some transistor circuit symbols have the circle around them and others not. Those without are widely used in the circuits detailing the internal circuitry of ICs as it is easier to incorporate the multiple emitters and other variations of the basic transistor if the circle is not included.

Table: Transistor Circuit Symbols

Symbol	Name	Description
	NPN Bipolar Transistor	Allows current flow when high potential at base
	PNP Bipolar Transistor	Allows current flow when low potential at base
	Darlington Transistor	Made from 2 bipolar transistors
	JFET-N Transistor	N-channel field effect transistor
	JFET-P Transistor	P-channel field effect transistor
	NMOS Transistor	N-channel MOSFET transistor
	PMOS Transistor	P-channel MOSFET transistor