1079:
70:
It breaks down a system into units, and then any number of sub-assemblies. The unit is the highest level of demarcation in a system and is always a numeral. Subsequent demarcation are called assemblies and always have the Class Letter "A" as a prefix following by a sequential number starting with
48:
IEEE 200-1975 or "Standard
Reference Designations for Electrical and Electronics Parts and Equipments" is a standard that was used to define referencing naming systems for collections of electronic equipment. IEEE 200 was ratified in 1975. The IEEE renewed the standard in the 1990s, but withdrew it
59:, a standards body for mechanical engineers, initiated the new standard ASME Y14.44-2008. This standard, along with IEEE 315-1975, provide the electrical designer with guidance on how to properly reference and annotate everything from a single circuit board to a collection of complete enclosures.
35:. The reference designator usually consists of one or two letters followed by a number, e.g. C3, D1, R4, U15. The number is sometimes followed by a letter, indicating that components are grouped or matched with each other, e.g. R17A, R17B. The
824:
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,
155:
The table below lists designators commonly used, and does not necessarily comply with standards. For modern use, designators are often simplified towards shorter designators, because it requires less space on silkscreens.
39:
315 standard 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.
1260:
IEEE 315-1975 / ANSI Standard Y32.2. Annex F: "Cross reference list of Class
Designation Letters" compares IEC 113-2:1971 to the IEEE/ANSI standard. * AS 1102 and IEC 60617 for "Graphical Symbols for Electrotechnology".
79:
assemblies (class designation 'U'). Inseparable assemblies—i.e., "items which are ordinarily replaced as a single item of supply"—are typically treated as components in this referencing scheme.
52:
This standard codified information from, among other sources, a United States military standard MIL-STD-16 which dates back to at least the 1950s in
American industry.
71:
1. Any number of sub-assemblies may be defined until finally reaching the component. Note that IEEE 315-1975 defines separate class designation letters for
1126:
1175:
147:
The construction of reference designators is covered by IEEE 200-1975/ANSI Y32.16-1975 (replaced by ASME Y14.44-2008) and IEEE 315-1975.
141:
94:
Especially valuable is the method of referencing and annotating cables plus their connectors within and outside assemblies. Examples:
606:(most-movable connector of a connector pair), plug connector (connector may have "male" pin contacts and/or "female" socket contacts)
1120:
1273:
1234:
1248:
AS 1103.2-1982 - "Diagrams charts and tables for electrotechnology, Part 2: Item
Designation" (Superseded by AS 3702-1989.)
997:
350:
sometimes changed to "L" for inductor, though "E" was used in the currently inactive standard IEEE 315 (see Clause 22.4).
1151:
IEEE Standard 315-1975: Graphic
Symbols for Electrical and Electronics Diagrams (Including Reference Designation Letters)
1015:
1054:
1048:
370:
901:
190:
177:
907:
101:
1A1A45J333 - Unit 1, Assembly 1, Sub-Assembly 45, Jack 333 (J333 is a connector on a box referenced as A45)
943:
67:
ASME Y14.44-2008 and IEEE 315-1975 define how to reference and annotate components of electronic devices.
49:
from active support shortly thereafter. This document also has an ANSI document number, ANSI Y32.16-1975.
991:
883:
843:
220:
32:
1227:"Item Designations; or "Why are relays called 'K' in schematics? Why are circuit breakers called 'Q'?""
979:
955:
889:
470:
459:
278:
133:
98:
1A1A44J5 - Unit 1, Assembly 1, Sub-Assembly 44, Jack 5 (J5 is a connector on a box referenced as A44)
24:
1251:
AS 3702-1989 - "Item designation in electrotechnology". (Equivalent to IEC 60750 Edition 1.0, 1983.)
768:
436:
1200:
Standard
Reference Designations for Electrical and Electronics Parts and Equipments: IEEE 200-1975
1122:
Reference
Designations for Electrical and Electronics Parts and Equipment: ASME Y14.44-2008(R2014)
1084:
1042:
937:
925:
835:
780:
485:
418:
382:
140:) is the more fixed and P (or plug) is the less fixed of a connector pair, without regard to the
1171:
1097:
839:
810:
806:
333:
295:
1163:
895:
603:
358:
206:
137:
129:
125:
1092:
961:
913:
874:
723:
often changed to "Q", but sometimes "T" is used for bipolar transistors and "Q" for FETs.
249:
194:
28:
556:
463:
320:
224:
1267:
949:
590:
307:
731:
616:
517:
345:
1226:
816:
voltage regulators are often "U" for IC, pots and trimmers often "R" for resistor
1003:
855:
794:
755:
540:
1167:
1078:
1149:
1074:
1036:
967:
919:
743:
718:
666:
628:
568:
474:
432:
386:
985:
706:
501:
282:
261:
237:
679:
653:
641:
513:
466:(connector may have "male" pin contacts and/or "female" socket contacts)
1030:
90:
1A12A2U3 - Unit 1, Assembly 12, Sub-assembly 2, Inseparable
Assembly 3
1257:
IEC 750-1983 (AS 3702 is equivalent, but provides extra information.)
1024:
973:
692:
544:
1009:
497:
274:
1207:
1203:
1159:
1155:
1063:
931:
56:
36:
658:
sometimes simplified to "R" for resistor, or "N" for network
421:, e.g., screws, nuts, washers, also used for drilled holes
87:
1A12A2R3 - Unit 1, Assembly 12, Sub-assembly 2, Resistor 3
1115:
1113:
109:1A1W35 - In the assembly A1 is a cable called W35.
974:Metal-oxide-semiconductor field-effect transistor
1254:IEC 113 (Superseded by IEC 750, i.e. IEC 60750.)
786:shorter "U" (unit) is preferred instead of "IC"
580:Mechanical part (including screws and fasteners)
1143:
1141:
1139:
1137:
462:(least-movable connector of a connector pair),
113:Connectors on this cable would be designated:
287:"D" is preferred for various types of diodes
124:ASME Y14.44-2008 continues the convention of
8:
914:Gas discharge tube, surge voltage protector
23:unambiguously identifies the location of a
16:Location identifier for a circuit component
323:, general light source, lamp, signal light
1148:"Chapter 22. Class Designation Letters".
671:sometimes simplified to "R" for resistor
176:Separable assembly or sub-assembly (e.g.
1127:American Society of Mechanical Engineers
158:
1109:
424:sometimes hardware is expanded to "HW"
266:may be simplified to "C" for capacitor
105:A cable connecting these two might be:
75:assemblies (class designation 'A') and
760:sometimes changed to "L" for inductor
932:Junction gate field-effect transistor
7:
813:(potentiometer / trimmer / rheostat)
698:sometimes "SW" is erroneously used
312:may be simplified to "D" for diode
14:
1077:
132:J when assigning references for
1237:from the original on 2024-07-17
860:often changed to "D" for diode
532:often changed to "D" for diode
451:often changed to "D" for diode
212:often changed to "D" for diode
1125:. Fairfield, New Jersey, USA:
1031:Thin-film transistor (display)
1020:SUS: Silicon unilateral switch
695:(all types, including buttons)
1:
1131:(NB. Replaced IEEE 200-1975.)
998:Programmable logic controller
1016:Silicon-controlled rectifier
595:often changed to "U" for IC
136:in assemblies where a J (or
144:of the connector contacts.
1290:
1168:10.1109/IEEESTD.1993.93397
1055:Vacuum fluorescent display
1049:Voltage-dependent resistor
209:(four diodes in a package)
55:To replace IEEE 200-1975,
950:Light-dependent resistor
902:Digital signal processor
879:ASSY: Separable assembly
809:(voltage reference), or
178:printed circuit assembly
1198:"Section 4.1.5.3 (2)".
1059:VT: Voltage transformer
908:Field-effect transistor
229:often shortened to "B"
1274:Electronic engineering
1212:(NB. Reaffirmed 1988.)
1188:(NB. Reaffirmed 1993.)
944:Liquid crystal display
277:(all types, including
992:Printed circuit board
134:electrical connectors
33:printed circuit board
980:Metal-oxide varistor
956:Light-emitting diode
926:Wire link ("jumper")
29:electrical schematic
21:reference designator
682:, variable resistor
437:directional coupler
1085:Electronics portal
1043:Variable capacitor
938:Lightning arrester
844:powered oscillator
781:Integrated circuit
1202:. New York, USA:
1177:978-0-7381-0947-3
1154:. New York, USA:
1098:Electronic symbol
867:Other designators
864:
863:
840:ceramic resonator
811:variable resistor
807:Voltage regulator
262:Capacitor network
1281:
1245:
1243:
1242:
1213:
1211:
1195:
1189:
1187:
1185:
1184:
1145:
1132:
1130:
1117:
1087:
1082:
1081:
896:Cathode ray tube
654:Resistor network
207:Bridge rectifier
159:
1289:
1288:
1284:
1283:
1282:
1280:
1279:
1278:
1264:
1263:
1240:
1238:
1229:. Engineering.
1225:
1222:
1220:Further reading
1217:
1216:
1197:
1196:
1192:
1182:
1180:
1178:
1162:. 1993-12-02 .
1147:
1146:
1135:
1119:
1118:
1111:
1106:
1093:Circuit diagram
1083:
1076:
1073:
1068:
962:circuit breaker
960:MCB: Miniature
875:Aerial, antenna
869:
408:General network
250:Circuit breaker
165:Component type
153:
65:
46:
17:
12:
11:
5:
1287:
1285:
1277:
1276:
1266:
1265:
1262:
1261:
1258:
1255:
1252:
1249:
1246:
1233:. 2018-07-01.
1221:
1218:
1215:
1214:
1190:
1176:
1133:
1108:
1107:
1105:
1102:
1101:
1100:
1095:
1089:
1088:
1072:
1069:
1067:
1066:
1060:
1057:
1051:
1045:
1039:
1033:
1027:
1021:
1018:
1012:
1006:
1000:
994:
988:
982:
976:
970:
964:
958:
952:
946:
940:
934:
928:
922:
916:
910:
904:
898:
892:
886:
880:
877:
870:
868:
865:
862:
861:
858:
853:
849:
848:
846:
833:
829:
828:
826:
822:
818:
817:
814:
804:
800:
799:
797:
792:
788:
787:
784:
778:
774:
773:
771:
766:
762:
761:
758:
753:
749:
748:
746:
741:
737:
736:
734:
729:
725:
724:
721:
716:
712:
711:
709:
707:Spark arrester
704:
700:
699:
696:
690:
686:
685:
683:
677:
673:
672:
669:
664:
660:
659:
656:
651:
647:
646:
644:
639:
635:
634:
632:
626:
622:
621:
619:
614:
610:
609:
607:
601:
597:
596:
593:
588:
584:
583:
581:
578:
574:
573:
571:
566:
562:
561:
559:
554:
550:
549:
547:
538:
534:
533:
530:
527:
523:
522:
520:
511:
507:
506:
504:
495:
491:
490:
488:
483:
479:
478:
467:
464:jack connector
457:
453:
452:
449:
448:Infrared diode
446:
442:
441:
439:
430:
426:
425:
422:
416:
412:
411:
409:
406:
402:
401:
399:
398:Graphical logo
396:
392:
391:
389:
380:
376:
375:
373:
368:
364:
363:
361:
356:
352:
351:
348:
343:
339:
338:
336:
331:
327:
326:
324:
318:
314:
313:
310:
305:
301:
300:
298:
293:
289:
288:
285:
272:
268:
267:
264:
259:
255:
254:
252:
247:
243:
242:
240:
235:
231:
230:
227:
225:battery holder
218:
214:
213:
210:
204:
200:
199:
197:
188:
184:
183:
181:
174:
170:
169:
166:
163:
152:
149:
122:
121:
118:
111:
110:
103:
102:
99:
92:
91:
88:
64:
61:
45:
42:
15:
13:
10:
9:
6:
4:
3:
2:
1286:
1275:
1272:
1271:
1269:
1259:
1256:
1253:
1250:
1247:
1236:
1232:
1228:
1224:
1223:
1219:
1209:
1205:
1201:
1194:
1191:
1179:
1173:
1169:
1165:
1161:
1157:
1153:
1152:
1144:
1142:
1140:
1138:
1134:
1128:
1124:
1123:
1116:
1114:
1110:
1103:
1099:
1096:
1094:
1091:
1090:
1086:
1080:
1075:
1070:
1065:
1061:
1058:
1056:
1052:
1050:
1046:
1044:
1040:
1038:
1034:
1032:
1028:
1026:
1022:
1019:
1017:
1013:
1011:
1007:
1005:
1001:
999:
995:
993:
989:
987:
983:
981:
977:
975:
971:
969:
965:
963:
959:
957:
953:
951:
947:
945:
941:
939:
935:
933:
929:
927:
923:
921:
917:
915:
911:
909:
905:
903:
899:
897:
893:
891:
887:
885:
881:
878:
876:
872:
871:
866:
859:
857:
854:
851:
850:
847:
845:
841:
837:
834:
831:
830:
827:
823:
820:
819:
815:
812:
808:
805:
802:
801:
798:
796:
793:
790:
789:
785:
782:
779:
776:
775:
772:
770:
767:
764:
763:
759:
757:
754:
751:
750:
747:
745:
742:
739:
738:
735:
733:
730:
727:
726:
722:
720:
717:
714:
713:
710:
708:
705:
702:
701:
697:
694:
691:
688:
687:
684:
681:
678:
675:
674:
670:
668:
665:
662:
661:
657:
655:
652:
649:
648:
645:
643:
640:
637:
636:
633:
630:
627:
624:
623:
620:
618:
615:
612:
611:
608:
605:
602:
599:
598:
594:
592:
591:Opto-isolator
589:
586:
585:
582:
579:
576:
575:
572:
570:
567:
564:
563:
560:
558:
555:
552:
551:
548:
546:
542:
539:
536:
535:
531:
528:
525:
524:
521:
519:
515:
512:
509:
508:
505:
503:
499:
496:
493:
492:
489:
487:
486:Jumper (link)
484:
481:
480:
476:
472:
469:all types of
468:
465:
461:
458:
455:
454:
450:
447:
444:
443:
440:
438:
434:
431:
428:
427:
423:
420:
417:
414:
413:
410:
407:
404:
403:
400:
397:
394:
393:
390:
388:
384:
381:
378:
377:
374:
372:
369:
366:
365:
362:
360:
357:
354:
353:
349:
347:
344:
341:
340:
337:
335:
332:
329:
328:
325:
322:
319:
316:
315:
311:
309:
308:Diode network
306:
303:
302:
299:
297:
294:
291:
290:
286:
284:
280:
276:
273:
270:
269:
265:
263:
260:
257:
256:
253:
251:
248:
245:
244:
241:
239:
236:
233:
232:
228:
226:
222:
219:
216:
215:
211:
208:
205:
202:
201:
198:
196:
192:
189:
186:
185:
182:
179:
175:
172:
171:
167:
164:
161:
160:
157:
150:
148:
145:
143:
139:
135:
131:
127:
119:
116:
115:
114:
108:
107:
106:
100:
97:
96:
95:
89:
86:
85:
84:
81:
78:
74:
68:
62:
60:
58:
53:
50:
43:
41:
38:
34:
30:
26:
22:
1239:. Retrieved
1231:penwatch.net
1230:
1199:
1193:
1181:. Retrieved
1150:
1121:
732:Thermocouple
617:Power supply
518:ferrite bead
473:, including
346:Ferrite bead
154:
146:
123:
112:
104:
93:
82:
76:
72:
69:
66:
54:
51:
47:
20:
18:
856:Zener diode
795:Vacuum tube
756:Transformer
631:(all types)
541:Loudspeaker
516:or coil or
475:pin headers
168:Modern use
162:Designator
151:Designators
77:inseparable
1241:2024-07-17
1183:2024-07-16
1104:References
1037:Thermistor
968:Microphone
920:Pin header
912:GDT, SVP:
832:X, XTAL, Y
744:Test point
719:Transistor
667:Thermistor
629:Transistor
569:Microphone
471:connectors
433:Circulator
387:oscillator
296:Delay line
191:Attenuator
83:Examples:
63:Definition
27:within an
1008:RY, RLA:
986:Neon lamp
890:Connector
502:contactor
383:Generator
283:thyristor
238:Capacitor
73:separable
25:component
1268:Category
1235:Archived
1210:. 1988 .
1129:. 2014 .
1071:See also
972:MOSFET:
680:Varistor
642:Resistor
514:Inductor
419:Hardware
359:Fiducial
195:isolator
120:1A1W35P2
117:1A1W35P1
31:or on a
924:J, JW:
884:Battery
836:Crystal
565:MK, MIC
537:LS, SPK
526:LD, LED
321:Display
221:Battery
217:BT, BAT
44:History
1174:
1025:Switch
1004:Pickup
930:JFET:
693:Switch
545:buzzer
379:G, OSC
371:Filter
142:gender
128:P and
1053:VFD:
1047:VDR:
1029:TFT:
1014:SCR:
1010:Relay
996:PLC:
990:PCB:
978:MOV:
966:MIC:
954:LED:
948:LDR:
942:LCD:
906:FET:
900:DSP:
894:CRT:
825:etc.)
777:U, IC
769:Tuner
752:TR, T
557:Motor
498:Relay
275:Diode
271:D, CR
1208:ANSI
1204:IEEE
1172:ISBN
1160:ANSI
1156:IEEE
1064:Wire
1041:VC:
1035:TH:
1023:SW:
1002:PU:
984:NE:
936:LA:
888:CN:
873:AE:
783:(IC)
604:Plug
460:Jack
334:Fuse
138:jack
130:Jack
126:Plug
57:ASME
37:IEEE
1164:doi
1062:W:
918:H:
882:B:
765:TUN
543:or
529:LED
500:or
435:or
385:or
281:),
279:LED
223:or
193:or
1270::
1206:/
1170:.
1158:/
1136:^
1112:^
852:ZD
842:,
838:,
803:VR
740:TP
728:TC
703:SA
676:RV
663:RT
650:RN
613:PS
587:OP
577:MP
482:JP
477:.
445:IR
429:HY
405:GN
395:GL
367:FL
355:FD
342:FB
317:DS
304:DN
292:DL
258:CN
246:CB
203:BR
187:AT
19:A
1244:.
1186:.
1166::
821:X
791:V
715:T
689:S
638:R
625:Q
600:P
553:M
510:L
494:K
456:J
415:H
330:F
234:C
180:)
173:A
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