Transistor & FET Component Circuit Symbols

- circuit symbols or circuit diagram symbols for transistors, FETs and SCR related devices.

There are many different circuit symbols for transistors, FETs, MOSFETs and SCRs, thyristors, TRIACs and DIACs, etc.

This page provides circuit symbols for transistors, FETs, MOSFETs and SCRs, thyristors, TRIACs and DIACs.

The circuit symbols are based on those that appear to be most widely used.

Basic bipolar transistor circuit symbols

The selection of transistor circuit diagram symbols:

Schematic symbol for a basic transistor showing the three electrodes: base, emitter, collector
Bipolar transistor (NPN - this type is the more widely used variety)

Schematic symbol for the transistor showing the inward facing arrow indicating a PNP transistor
Bipolar transistor (PNP)

Schematic symbol for a bipolar transistor. No circle is shown round the device as this format is often used on some diagrams.
Bipolar transistor
(no circle around symbol as often seen)

Schemtic symbol for a bipolar junction transistor showing the base emitter and collector plainly marked.
Bipolar transistor
(with base, emitter and collector electrodes marked - this is generally only seen on basic circuits, i.e. for hobbyists etc)

Schematic symbol for a phototransistor with no base connection and arrows towards the transistor indicating incident light
Bipolar phototransistor
(with base not connected)

Schematic symbol for a phototransistor with an external base connection - the arrows towards the transistor indicate the incident light.
Bipolar phototransistor

Darlington transistor circuit symbols

Darlington transistor circuit diagram symbols:

Schematic symbol for the Darlington bipolar transistor showing how the emitter of the first or input transistor is connected directly into the base of the second.
Darlington transistor

Symbol for a basic photodarlington transistor with inbound arrows depicting the incident light - notice also the base in this transistor symbol is not connected
Photodarlington transistor

Schematic symbol for a photodarlington transistor with external base conenction - inbound arrows indicate the incident light and hence the photo-sensitivity
Photodarlington transistor with base connection

FET circuit symbols

Darlington transistor schematic diagram symbols:

Schematic symbol for a dual gate MOSFET showing the two gate connections as well as the channel, drain and source.
Dual gate MOSFET

SCR, TRIAC, & DIAC circuit symbols

SCR, TRIAC, & DIAC circuit diagram symbols:

Schematic symbol for a DIAC showing the two triangles back to back and the two bars giving a broad indication of its function and structure.

Schematic symbol fopr an SCR - Silicon Controleld Rectifier of Thyristor
Thyristor (Silicon Controleld Rectifier, SCR)

Schematic symbol for a TRIAC showing the gate, anode and cathode electrode names.

Symbol for the TRIAC showing the three electrodes but without their names on the symbol.
TRIAC (without electrode names, etc)

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