Transistor: labelled reference, IEC style

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Transistor: labelled reference, IEC style, sheet 1 of 2

  1. Fig. 1

    BCE

    NPN transistor

    A bipolar transistor has base, collector and emitter terminals. In the current-controlled model used here, base drive controls conduction between collector and emitter.

  2. Fig. 2

    BCE

    PNP transistor

    The arrow is always on the emitter. It points out of the transistor for NPN and into it for PNP, whichever way the symbol is rotated.

  3. Fig. 3

    GDS

    N-channel MOSFET

    A MOSFET uses gate voltage relative to source to control its channel between drain and source. The three-terminal form shown here connects its body internally to source.

  4. Fig. 4

    GDS

    P-channel MOSFET

    In the body-arrow MOSFET convention used here, the arrow points toward the channel for N-channel and away for P-channel. Other MOSFET symbol forms place the arrow differently.

Notes

  1. The terminal key and the sources are on sheet 2.
Name
Class
Date
Sheet
1 of 2
Drawing
Transistor Labelled reference
Style
IEC style
From
circuitsymbols.com
Licence
CC BY 4.0

Transistor: labelled reference, IEC style, sheet 2 of 2

Terminal key
Fig.TerminalsWhat the terminal is
1, 2BThe base is the terminal drawn against the flat bar; a small base current controls the device.
1, 2CThe collector is the branch connected to the base bar that has no emitter arrow. The base has its own separate lead to that bar.
1, 2EThe arrow is always on the emitter. It points out of the transistor for NPN and into it for PNP, whichever way the symbol is rotated.
3, 4GThe gate is the insulated terminal drawn parallel to the channel with a gap between them.
3, 4DThe drain (D) is the other channel terminal: the channel runs between drain and source.
3, 4SThe source (S) is the channel terminal joined to the body in the three-terminal form shown here, so the controlling gate voltage is applied between gate and source.

Sources

  1. ModEL — Bipolar Junction Transistors, simplified tutorial and §4.2 (terminal roles), Tony R. Kuphaldt, retrieved 2026-09-22
  2. Lessons In Electric Circuits, Vol. V — §9, Circuit Schematic Symbols (pp. 130–139), Tony R. Kuphaldt, retrieved 2026-09-22
  3. ModEL — Field-Effect Transistors, §4.3 and §6.2 (body, channel and symbol alternatives), Tony R. Kuphaldt, retrieved 2026-09-22

Notes

  1. The Fig. numbers are those on sheet 1.
Name
Class
Date
Sheet
2 of 2
Drawing
Transistor Labelled reference
Style
IEC style
From
circuitsymbols.com
Licence
CC BY 4.0