Transistor emitter arrow

An arrow on one lead showing the device's polarity.

Also known as: NPN PNP arrow, Emitter arrow, Transistor polarity arrow

Engineering & technicalStandard profile

Meanings

The arrow on a transistor's emitter points in the direction of conventional current, which is what tells an NPN device from a PNP one. There is no other visual difference between them, so the direction of one small arrowhead determines how the whole circuit around it must be arranged.

Officially standardisedVerified fact
Marks the emitter lead of a bipolar transistor and points in the direction of conventional current flow through that lead.
Contexts: Technical drawing, Electrical equipment
Officially standardisedVerified fact
Is the only difference between the NPN and PNP symbols, so its direction determines the supply polarity the surrounding circuit must use.
Contexts: Technical drawing, Electrical equipment

Visual description

A short arrowhead placed on one of three leads meeting a vertical bar, pointing either towards or away from it.

Symmetry: none
Orientation: upright

Confidence

IdentityHigh confidence: High confidence because the identity is documented in encyclopedic references, but multiple independent sources agree.
Historical originModerate confidence: Moderate confidence because the historical origin is documented in encyclopedic references, but multiple independent sources agree, but early or supporting evidence is limited, but the regional or cultural match to this specific claim is not precise.
Current useHigh confidence: High confidence because the current use is documented in encyclopedic references, but multiple independent sources agree.
Visual matchHigh confidence: High confidence because the visual match is documented in encyclopedic references, but multiple independent sources agree.

Sources

ANSI Y32.2 / IEEE 315, Graphic Symbols for Electrical and Electronics Diagrams
IEEE / American National Standards Institute · retrieved 2026-08-22
Paywalled and NOT READ in full. Registered so the zig-zag resistor familiar from American schematics can be attributed to the standard that defines it, rather than described as the 'old' or 'wrong' form. See docs/paywalled-standards.md.
Electronic symbol
Wikipedia · retrieved 2026-07-31
Tertiary reference. Used for what the component is, how its symbol is conventionally drawn, and where the ANSI and IEC conventions differ. Not used for any claim about the text of IEC 60617, which is paywalled and was not consulted.
IEC 60617, Graphical symbols for diagrams
International Electrotechnical Commission · retrieved 2026-08-22
Maintained as an online database and NOT READ in full. Registered so a circuit-diagram record can say which body defines its symbol, and so the divergence between the IEC form and the older American form can be recorded as a real standards difference rather than a drawing preference. See docs/paywalled-standards.md.
Circuit diagram
Wikipedia · retrieved 2026-07-31
Tertiary reference. Used for what the component is, how its symbol is conventionally drawn, and where the ANSI and IEC conventions differ. Not used for any claim about the text of IEC 60617, which is paywalled and was not consulted.

Last reviewed 2026-08-23

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Circuit and electronic symbols

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Meanings

Officially standardisedVerified fact

Marks the emitter lead of a bipolar transistor and points in the direction of conventional current flow through that lead.

Contexts: Technical drawing, Electrical equipment

Officially standardisedVerified fact

Is the only difference between the NPN and PNP symbols, so its direction determines the supply polarity the surrounding circuit must use.

Contexts: Technical drawing, Electrical equipment

Confidence

IdentityHigh confidence: High confidence because the identity is documented in encyclopedic references, but multiple independent sources agree.
Historical originModerate confidence: Moderate confidence because the historical origin is documented in encyclopedic references, but multiple independent sources agree, but early or supporting evidence is limited, but the regional or cultural match to this specific claim is not precise.
Current useHigh confidence: High confidence because the current use is documented in encyclopedic references, but multiple independent sources agree.
Visual matchHigh confidence: High confidence because the visual match is documented in encyclopedic references, but multiple independent sources agree.

Sources

ANSI Y32.2 / IEEE 315, Graphic Symbols for Electrical and Electronics Diagrams
IEEE / American National Standards Institute · retrieved 2026-08-22
Paywalled and NOT READ in full. Registered so the zig-zag resistor familiar from American schematics can be attributed to the standard that defines it, rather than described as the 'old' or 'wrong' form. See docs/paywalled-standards.md.
Electronic symbol
Wikipedia · retrieved 2026-07-31
Tertiary reference. Used for what the component is, how its symbol is conventionally drawn, and where the ANSI and IEC conventions differ. Not used for any claim about the text of IEC 60617, which is paywalled and was not consulted.
IEC 60617, Graphical symbols for diagrams
International Electrotechnical Commission · retrieved 2026-08-22
Maintained as an online database and NOT READ in full. Registered so a circuit-diagram record can say which body defines its symbol, and so the divergence between the IEC form and the older American form can be recorded as a real standards difference rather than a drawing preference. See docs/paywalled-standards.md.
Circuit diagram
Wikipedia · retrieved 2026-07-31
Tertiary reference. Used for what the component is, how its symbol is conventionally drawn, and where the ANSI and IEC conventions differ. Not used for any claim about the text of IEC 60617, which is paywalled and was not consulted.

Last reviewed 2026-08-23