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.
In Partnership with Würth Elektronik eiSos GmbH & Co. KG
by Dale Wilson
by Jake Hertz