Editing Resistor (section)

==Resistor marking==
{{Main article|Electronic color code}}
[[File:ResistorColorCodeGuide.jpg|thumb|right|Wheel-based [[Radio Manufacturers Association|RMA]] Resistor Color Code guide. Circa 1945–1950.]]

Axial resistor cases are usually tan, brown, blue, or green (though other colors are occasionally found as well, such as dark red or dark gray), and display three to six colored stripes that indicate resistance (and by extension tolerance), and may include bands to indicate the temperature coefficient and reliability class. In four-striped resistors, the first two stripes represent the first two digits of the resistance in [[ohm]]s, the third represents a [[Multiplication#Notation and terminology|multiplier]], and the fourth the tolerance (which if absent, denotes ±20%). For five- and six- striped resistors the third band is the third digit, the fourth is the multiplier and the fifth is the tolerance; a sixth stripe represents the temperature coefficient. The power rating of the resistor is usually not marked and is deduced from its size.

[[Surface-mount]] resistors are marked numerically.

Early 20th century resistors, essentially uninsulated, were dipped in paint to cover their entire body for color-coding. This base color represented the first digit. A second color of paint was applied to one end of the element to represent a second digit, and a color dot (or band) in the middle provided the third digit. The rule was "body, tip, dot", providing two significant digits for value and the decimal multiplier, in that sequence. Default tolerance was ±20%. Closer-tolerance resistors had silver (±10%) or gold-colored (±5%) paint on the other end.

===Preferred values===
{{See also|E-series of preferred numbers}}
Early resistors were made in more or less arbitrary round numbers; a series might have 100, 125, 150, 200, 300, etc.<ref>{{cite web |title=1940 Catalog – page 60 – Resistors |url=http://www.radioshackcatalogs.com/html/1940/hr060.html |website=[[RadioShack]] |access-date=11 July 2017 |archive-url=https://web.archive.org/web/20170711160604/http://www.radioshackcatalogs.com/html/1940/hr060.html |archive-date=11 July 2017}}</ref> Early power wirewound resistors, such as brown vitreous-enameled types, were made with a system of preferred values like some of those mentioned here. Resistors as manufactured are subject to a certain percentage [[Engineering tolerance|tolerance]], and it makes sense to manufacture values that correlate with the tolerance, so that the actual value of a resistor overlaps slightly with its neighbors. Wider spacing leaves gaps; narrower spacing increases manufacturing and inventory costs to provide resistors that are more or less interchangeable.

A logical scheme is to produce resistors in a range of values which increase in a [[geometric progression]], so that each value is greater than its predecessor by a fixed multiplier or percentage, chosen to match the tolerance of the range. For example, for a tolerance of ±20% it makes sense to have each resistor about 1.5 times its predecessor, covering a decade in 6 values. More precisely, the factor used is 1.4678 ≈ <math>10^{1/6}</math>, giving values of 1.47, 2.15, 3.16, 4.64, 6.81, 10 for the 1–10-decade (a decade is a range increasing by a factor of 10; 0.1–1 and 10–100 are other examples); these are rounded in practice to 1.5, 2.2, 3.3, 4.7, 6.8, 10; followed by 15, 22, 33, ... and preceded by ... 0.47, 0.68, 1. This scheme has been adopted as the [[E6 (number series)|E6 series]] of the [[International Electrotechnical Commission|IEC]] 60063 [[preferred number]] values. There are also '''E12''', '''E24''', '''E48''', '''E96''' and '''E192''' series for components of progressively finer resolution, with 12, 24, 48, 96, and 192 different values within each decade. The actual values used are in the [[International Electrotechnical Commission|IEC]] 60063 lists of preferred numbers.

A resistor of 100 ohms ±20% would be expected to have a value between 80 and 120 ohms; its E6 neighbors are 68 (54–82) and 150 (120–180) ohms.  A sensible spacing, E6 is used for ±20% components; E12 for ±10%; E24 for ±5%; E48 for ±2%, E96 for ±1%; E192 for ±0.5% or better. Resistors are manufactured in values from a few milliohms to about a gigaohm in IEC60063 ranges appropriate for their tolerance. Manufacturers may sort resistors into tolerance-classes based on measurement.  Accordingly, a selection of 100 ohms resistors with a tolerance of ±10%, might not lie just around 100 ohm (but no more than 10% off) as one would expect (a bell-curve), but rather be in two groups – either between 5 and 10% too high or 5 to 10% too low (but not closer to 100 ohm than that) because any resistors the factory had measured as being less than 5% off would have been marked and sold as resistors with only ±5% tolerance or better.  When designing a circuit, this may become a consideration.  This process of sorting parts based on post-production measurement is known as "binning", and can be applied to other components than resistors (such as speed grades for CPUs).

===SMT resistors===
[[File:Zero ohm resistors cropped.jpg|thumb|This image shows four surface-mount resistors (the component at the upper left is a [[capacitor]]) including two [[zero-ohm resistor]]s. Zero-ohm links are often used instead of wire links, so that they can be inserted by a resistor-inserting machine. Their resistance is negligible. ]]

[[Surface-mount technology|Surface mounted]] resistors of larger sizes (metric [[Surface-mount technology#Packages|1608]] and above) are printed with numerical values in a code related to that used on axial resistors. Standard-tolerance [[surface-mount technology|surface-mount technology (SMT)]] resistors are marked with a three-digit code, in which the first two digits are the first two [[significant digit]]s of the value and the third digit is the power of ten (the number of zeroes). For example:

* 334 = 33 × 10<sup>4</sup> Ω = 330 kΩ
* 222 = 22 × 10<sup>2</sup> Ω = 2.2 kΩ
* 473 = 47 × 10<sup>3</sup> Ω = 47 kΩ
* 105 = 10 × 10<sup>5</sup> Ω = 1 MΩ

Resistances less than 100 Ω are written: 100, 220, 470. The final zero represents ten to the power zero, which is&nbsp;1. For example:

* 100 = 10 × 10<sup>0</sup> Ω = 10 Ω
* 220 = 22 × 10<sup>0</sup> Ω = 22 Ω

Sometimes these values are marked as 10 or 22 to prevent a mistake.

Resistances less than 10 Ω have 'R' to indicate the position of the decimal point ([[radix point]]). For example:

* 4R7 = 4.7 Ω
* R300 = 0.30 Ω
* 0R22 = 0.22 Ω
* 0R01 = 0.01 Ω

000 and 0000 sometimes appear as values on surface-mount [[zero-ohm link]]s, since these have (approximately) zero resistance.

More recent surface-mount resistors are too small, physically, to permit practical markings to be applied.

===Precision resistor markings===

Many precision resistors, including surface mount and axial-lead types, are marked with a four-digit code. The first three digits are the significant figures and the fourth is the power of ten. For example:

* 1001 = 100 × 10<sup>1</sup> Ω = 1.00 kΩ
* 4992 = 499 × 10<sup>2</sup> Ω = 49.9 kΩ
* 1000 = 100 × 10<sup>0</sup> Ω = 100 Ω

Axial-lead precision resistors often use color code bands to represent this four-digit code.

==== {{anchor|3-char-resistor-marking-code}}EIA-96 marking ====

The former EIA-96 marking system now included in [[IEC&nbsp;60062:2016]]<!-- not in earlier issues --> is a more compact marking system intended for physically small high-precision resistors. It uses a two-digit code plus a letter (a total of three alphanumeric characters) to indicate 1% resistance values to three significant digits.<ref>[https://eepower.com/resistor-guide/resistor-standards-and-codes/resistor-smd-code/ "Chapter 2 - Resistor standards and codes"].</ref> The two digits (from "01" to "96") are a code that indicates one of the 96 "positions" in the standard [[E96 series]] of 1% resistor values. The uppercase letter is a code that indicates a [[power of ten]] multiplier. For example, the marking "01C" represents 10&nbsp;kOhm; "10C" represents 12.4&nbsp;kOhm; "96C" represents 97.6&nbsp;kOhm.<ref>[https://www.bourns.com/pdfs/CRP0603.pdf "CRP0603 Series - Precision Chip Resistors"]. p. 3.</ref><ref>[http://kiloohm.info/eia96-resistor/96C "Online calculator - EIA-96 SMD resistor"].</ref><ref>[https://www.electricaltechnology.org/2013/07/how-to-calculate-or-find-value-of-smd.html "SMD Resistor Codes: How to Find the Value of SMD Resistors"].</ref><ref>[https://www.ttelectronics.com/TTElectronics/media/ProductFiles/ApplicationNotes/TN004-Methods-for-Marking-Values-on-Resistors.pdf "Marking Codes used on Welwyn Chip Resistors"]. p. 2.</ref><ref>[https://www.electronics-notes.com/articles/electronic_components/resistors/smt-smd-resistor-codes-markings.php "Surface Mount Resistor: codes & markings"].</ref>

{|
|
{| class="wikitable" style="float:left; margin-right:2em;"
!Code
!Series
!colspan="7"|Letter
|-
!Digits
!E96
!Y&nbsp;/&nbsp;S
!X&nbsp;/&nbsp;R
!A
!B&nbsp;/&nbsp;H
!C
!D
!E
|-
!01
!1.00
|1R00||10R0||100R||1K00||10K0||100K||1M00
|- 
!02
!1.02
|1R02||10R2||102R||1K02||10K2||102K||1M02
|-
!03
!1.05
|1R05||10R5||105R||1K05||10K5||105K||1M05
|-
!04
!1.07
|1R07||10R7||107R||1K07||10K7||107K||1M07
|-
!05
!1.10
|1R10||11R0||110R||1K10||11K0||110K||1M10
|-
!06
!1.13
|1R13||11R3||113R||1K13||11K3||113K||1M13
|-
!07
!1.15
|1R15||11R5||115R||1K15||11K5||115K||1M15
|-
!08
!1.18
|1R18||11R8||118R||1K18||11K8||118K||1M18
|-
!09
!1.21
|1R21||12R1||121R||1K21||12K1||121K||1M21
|-
!10
!1.24
|1R24||12R4||124R||1K24||12K4||124K||1M24
|-
!11
!1.27
|1R27||12R7||127R||1K27||12K7||127K||1M27
|-
!12
!1.30
|1R30||13R0||130R||1K30||13K0||130K||1M30
|-
!13
!1.33
|1R33||13R3||133R||1K33||13K3||133K||1M33
|-
!14
!1.37
|1R37||13R7||137R||1K37||13K7||137K||1M37
|-
!15
!1.40
|1R40||14R0||140R||1K40||14K0||140K||1M40
|-
!16
!1.43
|1R43||14R3||143R||1K43||14K3||143K||1M43
|-
!17
!1.47
|1R47||14R7||147R||1K47||14K7||147K||1M47
|-
!18
!1.50
|1R50||15R0||150R||1K50||15K0||150K||1M50
|-
!19
!1.54
|1R54||15R4||154R||1K54||15K4||154K||1M54
|-
!20
!1.58
|1R58||15R8||158R||1K58||15K8||158K||1M58
|-
!21
!1.62
|1R62||16R2||162R||1K62||16K2||162K||1M62
|-
!22
!1.65
|1R65||16R5||165R||1K65||16K5||165K||1M65
|-
!23
!1.69
|1R69||16R9||169R||1K69||16K9||169K||1M69
|-
!24
!1.74
|1R74||17R4||174R||1K74||17K4||174K||1M74
|-
!25
!1.78
|1R78||17R8||178R||1K78||17K8||178K||1M78
|-
!26
!1.82
|1R82||18R2||182R||1K82||18K2||182K||1M82
|-
!27
!1.87
|1R87||18R7||187R||1K87||18K7||187K||1M87
|-
!28
!1.91
|1R91||19R1||191R||1K91||19K1||191K||1M91
|-
!29
!1.96
|1R96||19R6||196R||1K96||19K6||196K||1M96
|-
!30
!2.00
|2R00||20R0||200R||2K00||20K0||200K||2M00
|-
!31
!2.05
|2R05||20R5||205R||2K05||20K5||205K||2M05
|-
!32
!2.10
|2R10||21R0||210R||2K10||21K0||210K||2M10
|-
!33
!2.15
|2R15||21R5||215R||2K15||21K5||215K||2M15
|-
!34
!2.21
|2R21||22R1||221R||2K21||22K1||221K||2M21
|-
!35
!2.26
|2R26||22R6||226R||2K26||22K6||226K||2M26
|-
!36
!2.32
|2R32||23R2||232R||2K32||23K2||232K||2M32
|-
!37
!2.37
|2R37||23R7||237R||2K37||23K7||237K||2M37
|-
!38
!2.43
|2R43||24R3||243R||2K43||24K3||243K||2M43
|-
!39
!2.49
|2R49||24R9||249R||2K49||24K9||249K||2M49
|-
!40
!2.55
|2R55||25R5||255R||2K55||25K5||255K||2M55
|-
!41
!2.61
|2R61||26R1||261R||2K61||26K1||261K||2M61
|-
!42
!2.67
|2R67||26R7||267R||2K67||26K7||267K||2M67
|-
!43
!2.74
|2R74||27R4||274R||2K74||27K4||274K||2M74
|-
!44
!2.80
|2R80||28R0||280R||2K80||28K0||280K||2M80
|-
!45
!2.87
|2R87||28R7||287R||2K87||28K7||287K||2M87
|-
!46
!2.94
|2R94||29R4||294R||2K94||29K4||294K||2M94
|-
!47
!3.01
|3R01||30R1||301R||3K01||30K1||301K||3M01
|-
!48
!3.09
|3R09||30R9||309R||3K09||30K9||309K||3M09
|}
|
{| class="wikitable" style="float: right; margin-right: 2em;"
!Code
!Series
!colspan="7"|Letter
|-
!Digits
!E96
!Y&nbsp;/&nbsp;S
!X&nbsp;/&nbsp;R
!A
!B&nbsp;/&nbsp;H
!C
!D
!E
|-
!49
!3.16
|3R16||31R6||316R||3K16||31K6||316K||3M16
|-
!50
!3.24
|3R24||32R4||324R||3K24||32K4||324K||3M24
|-
!51
!3.32
|3R32||33R2||332R||3K32||33K2||332K||3M32
|-
!52
!3.40
|3R40||34R0||340R||3K40||34K0||340K||3M40
|-
!53
!3.48
|3R48||34R8||348R||3K48||34K8||348K||3M48
|-
!54
!3.57
|3R57||35R7||357R||3K57||35K7||357K||3M57
|-
!55
!3.65
|3R65||36R5||365R||3K65||36K5||365K||3M65
|-
!56
!3.74
|3R74||37R4||374R||3K74||37K4||374K||3M74
|-
!57
!3.83
|3R83||38R3||383R||3K83||38K3||383K||3M83
|-
!58
!3.92
|3R92||39R2||392R||3K92||39K2||392K||3M92
|-
!59
!4.02
|4R02||40R2||402R||4K02||40K2||402K||4M02
|-
!60
!4.12
|4R12||41R2||412R||4K12||41K2||412K||4M12
|-
!61
!4.22
|4R22||42R2||422R||4K22||42K2||422K||4M22
|-
!62
!4.32
|4R32||43R2||432R||4K32||43K2||432K||4M32
|-
!63
!4.42
|4R42||44R2||442R||4K42||44K2||442K||4M42
|-
!64
!4.53
|4R53||45R3||453R||4K53||45K3||453K||4M53
|-
!65
!4.64
|4R64||46R4||464R||4K64||46K4||464K||4M64
|-
!66
!4.75
|4R75||47R5||475R||4K75||47K5||475K||4M75
|-
!67
!4.87
|4R87||48R7||487R||4K87||48K7||487K||4M87
|-
!68
!4.99
|4R99||49R9||499R||4K99||49K9||499K||4M99
|-
!69
!5.11
|5R11||51R1||511R||5K11||51K1||511K||5M11
|-
!70
!5.23
|5R23||52R3||523R||5K23||52K3||523K||5M23
|-
!71
!5.36
|5R36||53R6||536R||5K36||53K6||536K||5M36
|-
!72
!5.49
|5R49||54R9||549R||5K49||54K9||549K||5M49
|-
!73
!5.62
|5R62||56R2||562R||5K62||56K2||562K||5M62
|-
!74
!5.76
|5R76||57R6||576R||5K76||57K6||576K||5M76
|-
!75
!5.90
|5R90||59R0||590R||5K90||59K0||590K||5M90
|-
!76
!6.04
|6R04||60R4||604R||6K04||60K4||604K||6M04
|-
!77
!6.19
|6R19||61R9||619R||6K19||61K9||619K||6M19
|-
!78
!6.34
|6R34||63R4||634R||6K34||63K4||634K||6M34
|-
!79
!6.49
|6R49||64R9||649R||6K49||64K9||649K||6M49
|-
!80
!6.65
|6R65||66R5||665R||6K65||66K5||665K||6M65
|-
!81
!6.81
|6R81||68R1||681R||6K81||68K1||681K||6M81
|-
!82
!6.98
|6R98||69R8||698R||6K98||69K8||698K||6M98
|-
!83
!7.15
|7R15||71R5||715R||7K15||71K5||715K||7M15
|-
!84
!7.32
|7R32||73R2||732R||7K32||73K2||732K||7M32
|-
!85
!7.50
|7R50||75R0||750R||7K50||75K0||750K||7M50
|-
!86
!7.68
|7R68||76R8||768R||7K68||76K8||768K||7M68
|-
!87
!7.87
|7R87||78R7||787R||7K87||78K7||787K||7M87
|-
!88
!8.06
|8R06||80R6||806R||8K06||80K6||806K||8M06
|-
!89
!8.25
|8R25||82R5||825R||8K25||82K5||825K||8M25
|-
!90
!8.45
|8R45||84R5||845R||8K45||84K5||845K||8M45
|-
!91
!8.66
|8R66||86R6||866R||8K66||86K6||866K||8M66
|-
!92
!8.87
|8R87||88R7||887R||8K87||88K7||887K||8M87
|-
!93
!9.09
|9R09||90R9||909R||9K09||90K9||909K||9M09
|-
!94
!9.31
|9R31||93R1||931R||9K31||93K1||931K||9M31
|-
!95
!9.53
|9R53||95R3||953R||9K53||95K3||953K||9M53
|-
!96
!9.76
|9R76||97R6||976R||9K76||97K6||976K||9M76
|}
|}
{{clear}}

===Industrial type designation===
{| class="wikitable" style="float: left; margin-right: 2em;"
|+Power Rating at 70&nbsp;°C
!Type no.
!Power<br />rating<br />(watts)
![[MIL-R-11]]<br />style
![[MIL-R-39008]]<br />style
|- style="text-align: center;"
|BB||{{frac|1|8}}||RC05||RCR05
|- style="text-align: center;"
|CB||{{frac|1|4}}||RC07||RCR07
|- style="text-align: center;"
|EB||{{frac|1|2}}||RC20||RCR20
|- style="text-align: center;"
|GB||1||RC32||RCR32
|- style="text-align: center;"
|HB||2||RC42||RCR42
|- style="text-align: center;"
|GM||3||-||-
|- style="text-align: center;"
|HM||4||-||-
|}
{| class="wikitable" style="float: left;"
|+Tolerance code
|- style="text-align: center;"
!style="width: 75px;"|Industrial type designation
!style="width: 50px;"|Tolerance
!style="width: 75px;"|MIL designation
|- style="text-align: center;"
|5||±5%||J
|- style="text-align: center;"
|2||±20%||M
|- style="text-align: center;"
|1||±10%||K
|- style="text-align: center;"
| -||±2%||G
|- style="text-align: center;"
| -||±1%||F
|- style="text-align: center;"
| -||±0.5%||D
|- style="text-align: center;"
| -||±0.25%||C
|- style="text-align: center;"
| -||±0.1%||B
|}
{{clear}}

Steps to find out the resistance or capacitance values:<ref>Maini, A. K. (2008), ''Electronics and Communications Simplified'', 9th ed., Khanna Publications. {{ISBN|817409217X}}</ref>

# First two letters gives the power dissipation capacity.
# Next three digits gives the resistance value.
## First two digits are the significant values
## Third digit is the multiplier.
# Final digit gives the tolerance.

If a resistor is coded:
* EB1041: power dissipation capacity = 1/2 watts, resistance value = {{val|10|e=4}}±10% = between {{val|9|e=4}} ohms and {{val|11|e=4}} ohms.
* CB3932: power dissipation capacity = 1/4 watts, resistance value = {{val|39|e=3}}±20% = between {{val|31.2|e=3}} and {{val|46.8|e=3}} ohms.