Standard Reference Designators

<< Click to Display Table of Contents >>

Navigation:  Schematics >

Standard Reference Designators

A reference designator unambiguously identifies a component in an electrical schematic or on a printed circuit board. The reference designator usually consists of one or two letters followed by a number, e.g. R13, C1002. The number is sometimes followed by a letter, indicating that components are grouped or matched with each other, e.g. R17A, R17B. IEEE 315 contains a list of Class Designation Letters to use for electrical and electronic assemblies. For example, the letter R is a reference prefix for the resistors of an assembly, C for capacitors, K for relays.

Designator        

Component Type

A

Separable assembly or sub-assembly (e.g. printed circuit assembly)

AT

Attenuator or isolator

BR

Attenuator or isolator

C

Capacitor

CN

Capacitor network

D

Diode (including Zeners, thyristors and LEDs)

DL

Delay line

DS

Display

F

Fuse

FB or FEB

Ferrite bead

FD

Fiducial

FL

Filter

G

Generator or oscillator

GN

General network

H

Hardware

HY

Circulator or directional coupler

J

Jack (least-movable connector of a connector pair) | Jack connector (connector may have "male" pin contacts and/or "female" socket contacts)

JP

Link (Jumper)

K

Relay or contactor

L

Inductor or coil or ferrite bead

LS

Loudspeaker or buzzer

M

Motor

MK

Microphone

MP

Mechanical part (including screws and fasteners)

P

Plug (most-movable connector of a connector pair) | Plug connector (connector may have "male" pin contacts and/or "female" socket contacts)

PS

Power supply

Q

Transistor (all types)

R

Resistor

RN

Resistor network

RT

Thermistor

RV

Varistor

S

Switch (all types, including push-buttons)

T

Transformer

TC

Thermocouple

TUN

Tuner

TP

Test point

U

Inseparable assembly (e.g., integrated circuit)

V

Vacuum tube

VR

Variable resistor (potentiometer or rheostat)

X

Socket connector for another item not P or J, paired with the letter symbol for that item (XV for vacuum tube socket, XF for fuse holder, XA for printed circuit assembly connector, XU for integrated circuit connector, XDS for light socket, etc.)

Y

Crystal or oscillator

Z

Zener diode