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Component Library Reference

Reference specification for all 50 built-in CircuitMarkdown components, mnemonics, and pin definitions.

1. Overview

CircuitMarkdown includes 50 built-in schematic components. Every component connects to the 40-pixel integer grid.

Pin Addressing Rules

  • You can reference pins by number (such as 1, 2, 3) or by named alias (such as +, -, GND, OUT, B, C, E).
  • Wire statements use the format ComponentID.PinName (such as R1.1 or Q1.B).
  • Pin numbers match standard EDA numbering conventions.

2. Passives

Passive components store, dissipate, or restrict electric current.

Mnemonic Full Name Pins (Numbered) Pin Aliases Description
R Resistor 1, 2 None Two-terminal resistive element (zigzag style).
C Capacitor 1, 2 None Non-polarized capacitor with parallel plates.
C_POL Polarized Capacitor 1, 2 None Polarized capacitor with curved cathode plate.
L Inductor 1, 2 None Multi-turn inductor coil.
POT Potentiometer 1, 2, 3 L (pin 1), R (pin 2), W (pin 3) Three-terminal variable resistor with center wiper W.
LDR Photoresistor 1, 2 None Light-dependent resistor with inbound arrow indicator.
XFER Transformer 1, 2, 3, 4 None Four-terminal core-coupled primary and secondary transformer.
XTAL Crystal 1, 2 None Quartz crystal resonator.
FUSE Fuse 1, 2 None Overcurrent protection element with internal fuse link.

Example

R1 10k C1 100nF POT1 50k
R1 10k C1 100nF POT1 50k

3. Switches & Audio

Electromechanical switches and acoustic transducers.

Mnemonic Full Name Pins (Numbered) Pin Aliases Description
SW SPST Switch 1, 2 None Single-Pole Single-Throw toggle switch.
SPDT SPDT Switch 1, 2, 3 COM (pin 1), T1 (pin 2), T2 (pin 3) Single-Pole Double-Throw changeover switch with common terminal.
PB Pushbutton 1, 2 None Momentary normally open pushbutton.
SPKR Speaker / Buzzer 1, 2 None Acoustic speaker transducer.

Example

S1 Power SPKR1 8 Ohm
S1 Power SPKR1 8 Ohm

4. Diodes & Semiconductors

Two-terminal and three-terminal semiconductor rectifiers and solid-state devices.

Mnemonic Full Name Pins (Numbered) Pin Aliases Description
D Diode 1, 2 None Standard PN junction rectifier diode.
ZD Zener Diode 1, 2 None Voltage-regulating Zener diode with cathode wings.
SCHOTTKY Schottky Diode 1, 2 None Low forward drop Schottky barrier diode.
LED Light Emitting Diode 1, 2 None Light emitting diode with emission arrows.
PHOTODIODE Photodiode 1, 2 None Light-detecting diode with inward arrows.
VARACTOR Varactor Diode 1, 2 None Voltage-variable capacitance diode.
SCR Thyristor / SCR 1, 2, 3 A (pin 1), K (pin 2), G (pin 3) Silicon Controlled Rectifier with Anode, Cathode, Gate.
BRIDGE Bridge Rectifier 1, 2, 3, 4 + (pin 1), - (pin 2), ~1 (pin 3), ~2 (pin 4) Full-wave 4-diode rectifier package.

Example

D1 1N4148 LED1 Green
D1 1N4148 LED1 Green

5. Transistors & FETs

Bipolar and field-effect transistors for switching and amplification.

Mnemonic Full Name Pins (Numbered) Pin Aliases Description
NPN BJT NPN Transistor 1, 2, 3 E (pin 1), B (pin 2), C (pin 3) Bipolar junction NPN transistor with outward emitter arrow.
PNP BJT PNP Transistor 1, 2, 3 E (pin 1), B (pin 2), C (pin 3) Bipolar junction PNP transistor with inward emitter arrow.
MOS_N N-Channel MOSFET 1, 2, 3 S (pin 1), G (pin 2), D (pin 3) Enhancement N-channel MOSFET with Source, Gate, Drain.
MOS_P P-Channel MOSFET 1, 2, 3 S (pin 1), G (pin 2), D (pin 3) Enhancement P-channel MOSFET with Source, Gate, Drain.
JFET_N N-Channel JFET 1, 2, 3 S (pin 1), G (pin 2), D (pin 3) Junction field-effect transistor, N-channel.
JFET_P P-Channel JFET 1, 2, 3 S (pin 1), G (pin 2), D (pin 3) Junction field-effect transistor, P-channel.

Example

Q1 2N3904 M1 IRFZ44N
Q1 2N3904 M1 IRFZ44N

6. Sources, Power & Terminals

Power rails, energy sources, reference points, and external connector terminals.

Mnemonic Full Name Pins (Numbered) Pin Aliases Description
V DC Voltage Source 1, 2 + (pin 1), - (pin 2) Ideal constant DC voltage source.
BAT Single-Cell Battery 1, 2 + (pin 1), - (pin 2) Single-cell chemical battery.
BAT_MULTI Multi-Cell Battery 1, 2 + (pin 1), - (pin 2) Multi-cell battery source.
I DC Current Source 1, 2 + (pin 1), - (pin 2) Ideal constant DC current source with arrow.
AC AC Voltage Source 1, 2 + (pin 1), - (pin 2) Sinusoidal alternating current generator.
GND Ground Reference 1 GND (pin 1) 0V earth ground reference marker.
VCC Positive Supply Flag 1 VCC (pin 1) Positive power supply rail terminal arrow.
TERM Terminal Pin 1 TERM, PORT External connection terminal node.
PORT Interface Port 1 PORT, TERM I/O interface port terminal circle.

Example

VCC1 +5V GND1 R1 1k
VCC1 +5V GND1 R1 1k

7. Integrated Circuits & Logic Gates

Digital logic gates, operational amplifiers, multi-pin packages, and displays.

Mnemonic Full Name Pins (Numbered) Pin Aliases Description
OPAMP Operational Amplifier 1, 2, 3, 4, 5 + (pin 1), - (pin 2), OUT (pin 3), V+ (pin 4), V- (pin 5) Five-terminal operational amplifier with supply rails.
COMP Voltage Comparator 1, 2, 3, 4, 5 + (pin 1), - (pin 2), OUT (pin 3), V+ (pin 4), V- (pin 5) High-speed comparator with hysteresis symbol.
BUF Digital Buffer 1, 2 I (pin 1), O (pin 2) Non-inverting digital logic buffer.
NOT Inverter Gate 1, 2 I (pin 1), O (pin 2) Single-input digital NOT inverter gate.
AND 2-Input AND Gate 1, 2, 3 A (pin 1), B (pin 2), O (pin 3) Two-input logical AND gate.
OR 2-Input OR Gate 1, 2, 3 A (pin 1), B (pin 2), O (pin 3) Two-input logical OR gate.
NAND 2-Input NAND Gate 1, 2, 3 A (pin 1), B (pin 2), O (pin 3) Two-input logical NAND gate with inverted output bubble.
NOR 2-Input NOR Gate 1, 2, 3 A (pin 1), B (pin 2), O (pin 3) Two-input logical NOR gate with inverted output bubble.
XOR 2-Input XOR Gate 1, 2, 3 A (pin 1), B (pin 2), O (pin 3) Two-input logical Exclusive-OR gate.
DFF D Flip-Flop 1, 2, 3, 4 D (pin 1), CLK (pin 2), Q (pin 3), ~Q (pin 4) Edge-triggered D flip-flop with complementary outputs.
MUX 2-to-1 Multiplexer 1, 2, 3, 4 I0 (pin 1), I1 (pin 2), S (pin 3), O (pin 4) Two-input multiplexer with select input S.
8P_IC 8-Pin DIP IC 1 to 8 None Generic 8-pin Dual In-line Package with notch marker.
16P_IC 16-Pin DIP IC 1 to 16 None Generic 16-pin Dual In-line Package with notch marker.
7SEG 7-Segment Display 1 to 10 e (1), d (2), com1 (3), c (4), dp (5), b (6), a (7), com2 (8), f (9), g (10) Ten-pin common-anode / common-cathode 7-segment numerical display.

Example

U1A 74HC08 U2A 74HC04
U1A 74HC08 U2A 74HC04