Bipolar Transistor Circuit Symbols

Circuit symbols for the various forms of bipolar transistor: NPN, PNP, Darlington, photosensitive transistor or phototransistor . .

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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.

Other bipolar transistor circuit symbols include those for phototransistors and Darlington transistors, etc.

Bipolar Transistor Circuit Symbols
Transistor Description Circuit Symbol
NPN bipolar transistor NPN transistor circuit symbol
PNP bipolar transistor PNP transistor circuit symbol
NPN bipolar transistor
with electrodes marked.
NPN transistor circuit symbol
NPN bipolar transistor
with no outer circle
NPN transistor circuit symbol
NPN bipolar phototransistor NPN phototransistor circuit symbol
NPN bipolar phototransistor
with no base connection
NPN phototransistor circuit symbol - no base connection
NPN bipolar phototransistor Bipolar transistor darlington circuit symbol
NPN photodarlington NPN photodarlington circuit symbol
Transistor optocoupler circuit symbol Optocoupler circuit symbol

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