Circuit Symbols
Drawing style

Sources

The published documents behind the explanations on this site.

Standards

Document Publisher Read on
DIN 72552-2:2014-07 — Terminal markings for vehicles, Part 2: Codes (status page) DIN Media 2026-09-23
IEC 60062:2016+AMD1:2019 — Marking codes for resistors and capacitors; public preview contents (preview p. 3) International Electrotechnical Commission 2026-09-23
IEC 60417 — equipment-symbol overview: 5007, 5008 and 5009 (preview p. 6) International Electrotechnical Commission 2026-09-22
IEC 60617:2026 DB — Graphical symbols for diagrams International Electrotechnical Commission 2026-09-22
IEC 60947-5-1:2024 — control circuit devices; public preview contents, Annex M (preview p. 6) International Electrotechnical Commission 2026-09-23
IEEE 315-1975 — historical standard status IEEE Standards Association 2026-09-22

Textbooks and teaching material

Document Publisher Read on
DC Electrical Circuit Analysis — resistive devices and schematic ground symbols (pp. 53, 59–64) James M. Fiore, Mohawk Valley Community College 2026-09-22
Lessons In Electric Circuits, Vol. III — §2.8, bipolar junction transistors (emitter arrow, p. 63) Tony R. Kuphaldt 2026-09-23
Lessons In Electric Circuits, Vol. III — §3.1, diode representations (Figure 3.5, p. 100) Tony R. Kuphaldt 2026-09-23
Lessons In Electric Circuits, Vol. IV — §§3.2–3.4, the inversion bubble on gate symbols (pp. 31, 51) Tony R. Kuphaldt 2026-09-23
Lessons In Electric Circuits, Vol. IV — §§3.4.1–3.4.3, AND and OR gate symbols (pp. 49–52) Tony R. Kuphaldt 2026-09-23
Lessons In Electric Circuits, Vol. IV — §3.4.7, Exclusive-OR gate symbol (pp. 57–58) Tony R. Kuphaldt 2026-09-23
Lessons In Electric Circuits, Vol. IV — §12, shift-register pin diagram (nc pins, p. 356) Tony R. Kuphaldt 2026-09-23
Lessons In Electric Circuits, Vol. V — §9, Circuit Schematic Symbols (pp. 130–139) Tony R. Kuphaldt 2026-09-22
ModEL — AC Induction Motor Starters, §2.1 (contactor coil terminals A1 and A2, pp. 7–9) Tony R. Kuphaldt 2026-09-23
ModEL — Bipolar Junction Transistors, §4.3 note 8 (emitter arrow direction, p. 32) Tony R. Kuphaldt 2026-09-23
ModEL — Bipolar Junction Transistors, simplified tutorial (current directions and the emitter arrow, p. 20) Tony R. Kuphaldt 2026-09-23
ModEL — Bipolar Junction Transistors, simplified tutorial and §4.2 (terminal roles) Tony R. Kuphaldt 2026-09-22
ModEL — Capacitors and Capacitive Circuits, §3.6 (electrolytic capacitors, p. 53) Tony R. Kuphaldt 2026-09-23
ModEL — Capacitors and Capacitive Circuits, §5.2 (capacitor labelling and polarity stripes, pp. 70–72) Tony R. Kuphaldt 2026-09-23
ModEL — Components and Symbols, §§3.2–3.3 (meters in series and parallel, pp. 8–11) Tony R. Kuphaldt 2026-09-22
ModEL — Components and Symbols, §§3.4–3.6 (NEMA and IEC symbol families, pp. 11–13) Tony R. Kuphaldt 2026-09-23
ModEL — Components and Symbols, §3.5 (cells and ideal source symbols, p. 12) Tony R. Kuphaldt 2026-09-22
ModEL — Components and Symbols, §§3.6–3.7 (resistors and potentiometers, pp. 13–14) Tony R. Kuphaldt 2026-09-22
ModEL — Components and Symbols, §3.8 (switch symbols, poles, throws and dashed links, pp. 15–16) Tony R. Kuphaldt 2026-09-23
ModEL — Components and Symbols, §3.9 (solenoid coil symbols, p. 18) Tony R. Kuphaldt 2026-09-23
ModEL — Components and Symbols, §3.10 (fuses and circuit breakers, p. 20) Tony R. Kuphaldt 2026-09-22
ModEL — Components and Symbols, §3.11 (relay example with motor and lamp loads, p. 22) Tony R. Kuphaldt 2026-09-23
ModEL — Components and Symbols, §3.11 (relay symbol, p. 21) Tony R. Kuphaldt 2026-09-23
ModEL — Components and Symbols, §3.12 (electromagnetic generator symbol, p. 23) Tony R. Kuphaldt 2026-09-23
ModEL — Components and Symbols, §§3.13–3.14 (inductors and transformers, pp. 24–26) Tony R. Kuphaldt 2026-09-22
ModEL — Components and Symbols, §3.15 (capacitor polarity, pp. 27–28) Tony R. Kuphaldt 2026-09-22
ModEL — Components and Symbols, §3.16 (diodes, p. 29) Tony R. Kuphaldt 2026-09-23
ModEL — Components and Symbols, §3.17 (LED symbol, p. 31) Tony R. Kuphaldt 2026-09-23
ModEL — Components and Symbols, §3.20 (wire crossings and dashed links, p. 36) Tony R. Kuphaldt 2026-09-23
ModEL — Components and Symbols, §4.3 (capacitor labelling, p. 49) Tony R. Kuphaldt 2026-09-23
ModEL — Electrical Switches, §§3.1–3.3 (pp. 16–19) Tony R. Kuphaldt 2026-09-22
ModEL — Electrical Switches, §3.4 (making and breaking order, p. 20) Tony R. Kuphaldt 2026-09-23
ModEL — Electrical Switches, §§3.5.1–3.5.3 (toggle and pushbutton operators, p. 21) Tony R. Kuphaldt 2026-09-23
ModEL — Electromechanical Relays, §§3.2–3.3 and §5.1 (normal and present contact status) Tony R. Kuphaldt 2026-09-22
ModEL — Electromechanical Relays, §3.7 (latching relays, p. 41) Tony R. Kuphaldt 2026-09-23
ModEL — Field-Effect Transistors, §4.3 and §6.2 (body, channel and symbol alternatives) Tony R. Kuphaldt 2026-09-22
ModEL — Inductors and Inductive Circuits, §§3.1–3.2 (current change and polarity) Tony R. Kuphaldt 2026-09-22
ModEL — Ohm’s and Joule’s Laws, Resistor Ratings, and Electrical Safety, §6.2 (resistor labelling, p. 73) Tony R. Kuphaldt 2026-09-23
ModEL — PN Junctions and Diodes, §§2.3–2.7 (bias and diode variants) Tony R. Kuphaldt 2026-09-22
ModEL — Semiconductor Logic Gates, §2.1 (schematic versus package pinout, p. 8) Tony R. Kuphaldt 2026-09-23
ModEL — Semiconductor Logic Gates, §3.1 (truth tables, pp. 34–35) Tony R. Kuphaldt 2026-09-22
ModEL — Semiconductor Logic Gates, §3.4 (supply terminal labels VCC, VEE, VDD and VSS, p. 43) Tony R. Kuphaldt 2026-09-23
ModEL — Sources and Loads, Voltmeters and Ammeters, §§4.2–4.6 and §6.2 Tony R. Kuphaldt 2026-09-22
ModEL — Transformers, §§4.1, 4.3–4.4 (windings, centre taps, autotransformers and dots) Tony R. Kuphaldt 2026-09-22
ModEL — Transistor Switching Circuits, §§3.1–3.4 (cutoff and saturation) Tony R. Kuphaldt 2026-09-22
Modular Electronics Learning — authorship and CC BY 4.0 notice Tony R. Kuphaldt 2026-09-22
University Physics, Vol. 2, §8.1 — capacitor representations, Figure 8.9 OpenStax, Rice University 2026-09-22

Course notes

Document Publisher Read on
AT121 course notes — Relays: ISO relay contact numbers Community College of Philadelphia (D. Reed), reproducing with permission an MG Car Club article by Rick Astley 2026-09-23
Capacitor Codes (seminar handout) MIT Robotics and Electronics Cooperative 2026-09-23
Combined Science: Synergy, June 2022 paper — motor symbol (p. 47) AQA 2026-09-22
Diodes — terminal polarity, ideal and offset models (pp. 1–2, 7–10) MIT OpenCourseWare — Chaniotakis and Cory 2026-09-22
E84 — Bipolar Junction Transistor: terminals and optional symbol enclosure Ruye Wang, Harvey Mudd College 2026-09-22
ECE 2210 Capacitors Lab — electrolytic capacitors (p. 2) University of Utah, Department of Electrical and Computer Engineering 2026-09-23
ECE 3310, Experiment 9 — inductor core symbols, Figure 2 Wayne State University 2026-09-22
Electrical Schematics, §§1.3.1–1.3.5 — nodes, crossings, references and congruent drawings Tufts University 2026-09-22
Electromechanical: Switches and Relays (30 May 2024) Steven McDermott, CSE Senior Design Knowledge Base, University of Texas at Arlington 2026-09-23
Motor Branch Circuits Basics, IEC & NEMA Devices — numbers on IEC relay terminals (slides 17 and 24) Tom Wylie, IND223 course module, hosted by ATE Central (NSF Advanced Technological Education) 2026-09-23

Manufacturer documents

Document Publisher Read on
Chassis, Earth and Signal Grounding: Terminology and Symbols NI 2026-09-22
Circuit Breakers and Automatic Switches — breaker identification symbol (p. 10) Schneider Electric 2026-09-22
General Descriptions of Aluminum Electrolytic Capacitors — reverse polarity, §2-3-2 Nichicon 2026-09-22
Overview of IEEE Standard 91-1984 — Explanation of Logic Symbols, §§2–3 (pp. 2–5) Texas Instruments 2026-09-22
Relay technology — structure, operation and contact forms Omron 2026-09-22
Small-signal diode datasheet — forward-voltage graphs (p. 2) Vishay 2026-09-22
Thermistors — NTC and PTC product-description definitions Murata Manufacturing 2026-09-22
Where Is Ground? — local reference versus earth Analog Devices 2026-09-22

Encyclopedias

Document Publisher Read on
Logic gate — Symbols (revision 1376198871 of 22 September 2026) Wikipedia contributors 2026-09-23

Other

Document Publisher Read on
Design to Manufacturing Standards — Reference Designators (slide 33) Dieter Bergman, IPC 2026-09-22
Info Byte: What’s the Reason Behind Relay Terminal Numbering? (23 February 2022) David Peterson, Control.com 2026-09-23