E series of preferred numbers

From HandWiki
Short description: Series of preferred values for passive electrical components
Not to be confused with E notation or E number.

This graph shows how almost any value between 1 and 10 is within ±10% of an E12 series value, and its difference from the ideal value in a geometric sequence
Two decades of E12 values, which would give resistor values of 1 Ω to 82 Ω

The E series is a system of preferred numbers (also called preferred values) derived for use in electronic components. It consists of the E3, E6, E12, E24, E48, E96 and E192 series,[1] where the number after the 'E' designates the quantity of logarithmic value "steps" per decade. Although it is theoretically possible to produce components of any value, in practice the need for inventory simplification has led the industry to settle on the E series for resistors, capacitors, inductors, and zener diodes. Other types of electrical components are either specified by the Renard series (for example fuses) or are defined in relevant product standards (for example IEC 60228 for wires).

History

During the Golden Age of Radio (1920s to 1950s), numerous companies manufactured AM radio receivers for consumer use. In the early years, many components were not standardized between radio manufacturers. The capacitance values of capacitors (previously called condensers)[2][3] and resistance values of resistors[4][5][6][7] were not standardized.[8]

In 1924, the Radio Manufacturers Association (RMA) was formed in Chicago, Illinois by 50 radio manufacturers to license and share patents. Over time, this group created some of the earliest standards for electronics components. In 1936, the RMA adopted a preferred number system for the resistance values of fixed composition resistors.[9] Over time, resistor manufacturers migrated from older values to the 1936 resistance value standard.[6][7]

During World War II (1940s), American and British military production was a major influence for establishing common standards across many industries, especially in electronics, where it was essential to produce large quantities of standardized electronic parts for military wireless communication and Radar devices. Later, the mid-20th century baby boom and the invention of the transistor kicked off demand for consumer electronics goods during the 1950s. As transistor radio production migrated from United States towards Japan during the late-1950s, it was critical for the electronic industry to have international standards.

As worked on by the RMA,[10] the International Electrotechnical Commission (IEC) began work on an international standard in 1948.[11] The first version of this IEC Publication 63 (IEC 63) was released in 1952.[12] Later, IEC 63 was revised, amended, and renamed into the current version known as IEC 60063:2015.[13]

IEC 60063 release history:

  • IEC 63:1952 (aka IEC 60063:1952), first edition, published 1952-01-01.[12]
  • IEC 63:1963 (aka IEC 60063:1963), second edition, published 1963-01-01.[11]
  • IEC 63:1967/AMD1:1967 (aka IEC 60063:1967/AMD1:1967), first amendment of second edition, published 1967.[11]
  • IEC 63:1977/AMD2:1977 (aka IEC 60063:1977/AMD2:1977), second amendment of second edition, published 1977.[11]
  • IEC 60063:2015, third edition, published 2015-03-27.[13]

Overview

The E series of preferred numbers was chosen such that when a component is manufactured it will end up in a range of roughly equally spaced values (geometric progression) on a logarithmic scale. Each E series subdivides each decade magnitude into steps of 3, 6, 12, 24, 48, 96, 192 values.[nb 1] Subdivisions of E3 to E192 ensure the maximum error will be divided in the order of 40%, 20%, 10%, 5%, 2%, 1%, 0.5%. Also, the E192 series is used for 0.25% and 0.1% tolerance resistors.

Historically, the E series is split into two major groupings:

  • E3, E6, E12, E24 are subsets of E24. Values in this group are rounded to 2 significant figures.
  • E48, E96, E192 are subsets of E192. Values in this group are rounded to 3 significant figures.

Formula

The formula for each value is determined by the m-th root, though eight of the official E24 values and one of the official E192 values do not match the following formula.

[math]\displaystyle{ V_n = \mathrm{round} (\sqrt[m]{10^n}) }[/math]

where [math]\displaystyle{ V_n }[/math] is the rounded value, [math]\displaystyle{ m }[/math] is an integer of the E series group size, and [math]\displaystyle{ n }[/math] is an integer of [math]\displaystyle{ \{0, 1, 2, ..., m-1\} . }[/math]

E24 subsets

Since the electronic component industry established component values before standards discussions in the late-1940s, the standards organizations decided that it wasn't practical to change the former established values. These older values were used to create the E6, E12, E24 series standard that was accepted in Paris in 1950 then published as IEC 63 in 1952.

For E3 to E24, the values from the formula are rounded to 2 significant figures. For unknown historical reasons, eight older industry values (shown in bold) are different from the calculated values.

Comparison of rounded log-scaled values to de-facto standard of E24 series
[math]\displaystyle{ n }[/math] 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Calculated [math]\displaystyle{ V_n }[/math] values 1.0 1.1 1.2 1.3 1.5 1.6 1.8 2.0 2.2 2.4 2.6 2.9 3.2 3.5 3.8 4.2 4.6 5.1 5.6 6.2 6.8 7.5 8.3 9.1
Official E24 values 1.0 1.1 1.2 1.3 1.5 1.6 1.8 2.0 2.2 2.4 2.7 3.0 3.3 3.6 3.9 4.3 4.7 5.1 5.6 6.2 6.8 7.5 8.2 9.1

E192 subsets

For E48 to E192, the values from the formula are rounded to 3 significant figures. Consequently, the eight exceptional E24 series values shown in bold above do not exist in the E48, E96, E192 series. The E48 and E96 series follow the formula, as does E192 series but with one exception:

  • To calculate the E48 series: [math]\displaystyle{ m }[/math] is 48, then [math]\displaystyle{ n }[/math] is incremented from 0 to 47 through the formula.
  • To calculate the E96 series: [math]\displaystyle{ m }[/math] is 96, then [math]\displaystyle{ n }[/math] is incremented from 0 to 95 through the formula.
  • To calculate the E192 series: [math]\displaystyle{ m }[/math] is 192, then [math]\displaystyle{ n }[/math] is incremented from 0 to 191 through the formula, with one exception for [math]\displaystyle{ n=185 }[/math] where 9.20 is the official value instead of the calculated 9.19 value.

Exceptions

High tolerance families

The E3 series is rarely used,[nb 1] except for some components with high variations like electrolytic capacitors, where the given tolerance is often unbalanced between negative and positive such as +50%−30% or +80%−20%, or for components with uncritical values such as pull-up resistors. The calculated constant tangential tolerance for this series gives (3√10 − 1) ÷ (3√10 + 1) = 36.60%, approximately. While the standard only specifies a tolerance greater than 20%, other sources indicate 40% or 50%. Currently, most electrolytic capacitors are manufactured with values in the E6 or E12 series, thus E3 series is mostly obsolete.

Low tolerance families

Since some values of the E24 series do not exist in the E48 / E96 / E192 series, some resistor manufacturers have added missing E24 values into some of their 1%, 0.5%, 0.25%, 0.1% tolerance resistor families. This allows easier purchasing migration between various tolerances. This E series merging is noted on resistor datasheets and webpages as "E96 + E24" or "E192 + E24".[14][15][16]

Comparison of E24 vs. E48 values
Both E24 & E48 contains – 1.00, 1.10, 7.50
E48 is missing – 1.20, 1.30, 1.50, 1.60, 1.80, 2.00, 2.20, 2.40, 2.70, 3.00, 3.30, 3.60, 3.90, 4.30, 4.70, 5.10, 5.60, 6.20, 6.80, 8.20, 9.10
Comparison of E24 vs. E96 values
Both E24 & E96 contains – 1.00, 1.10, 1.30, 1.50, 2.00, 7.50
E96 is missing – 1.20, 1.60, 1.80, 2.20, 2.40, 2.70, 3.00, 3.30, 3.60, 3.90, 4.30, 4.70, 5.10, 5.60, 6.20, 6.80, 8.20, 9.10.
Comparison of E24 vs. E192 values
Both E24 & E192 contains – 1.00, 1.10, 1.20, 1.30, 1.50, 1.60, 1.80, 2.00, 2.40, 4.70, 7.50
E192 is missing – 2.20, 2.70, 3.00, 3.30, 3.60, 3.90, 4.30, 5.10, 5.60, 6.20, 6.80, 8.20, 9.10

Examples

If a manufacturer sold resistors with all values in a range of 1 ohm to 10 megaohms, the available resistance values for E3 through E12 would be:

E3 (in ohms) E6 (in ohms) E12 (in ohms)
  • 1.0, 2.2, 4.7,
  • 10, 22, 47,
  • 100, 220, 470,
  • 1 k, 2.2 k, 4.7 k,
  • 10 k, 22 k, 47 k,
  • 100 k, 220 k, 470 k,
  • 1 M, 2.2 M, 4.7 M,
  • 10 M
  • 1.0, 1.5, 2.2, 3.3, 4.7, 6.8,
  • 10, 15, 22, 33, 47, 68,
  • 100, 150, 220, 330, 470, 680,
  • 1 k, 1.5 k, 2.2 k, 3.3 k, 4.7 k, 6.8 k,
  • 10 k, 15 k, 22 k, 33 k, 47 k, 68 k,
  • 100 k, 150 k, 220 k, 330 k, 470 k, 680 k,
  • 1 M, 1.5 M, 2.2 M, 3.3 M, 4.7 M, 6.8 M,
  • 10 M
  • 1.0, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2,
  • 10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82,
  • 100, 120, 150, 180, 220, 270, 330, 390, 470, 560, 680, 820,
  • 1 k, 1.2 k, 1.5 k, 1.8 k, 2.2 k, 2.7 k, 3.3 k, 3.9 k, 4.7 k, 5.6 k, 6.8 k, 8.2 k,
  • 10 k, 12 k, 15 k, 18 k, 22 k, 27 k, 33 k, 39 k, 47 k, 56 k, 68 k, 82 k,
  • 100 k, 120 k, 150 k, 180 k, 220 k, 270 k, 330 k, 390 k, 470 k, 560 k, 680 k, 820 k,
  • 1 M, 1.2 M, 1.5 M, 1.8 M, 2.2 M, 2.7 M, 3.3 M, 3.9 M, 4.7 M, 5.6 M, 6.8 M, 8.2 M,
  • 10 M

If a manufacturer sold capacitors with all values in a range of 1 pF to 10,000 μF, the available capacitance values for E3 and E6 would be:

E3 E6
  • 1.0 pF, 2.2 pF, 4.7 pF,
  • 10 pF, 22 pF, 47 pF,
  • 100 pF, 220 pF, 470 pF,
  • 1 nF, 2.2 nF, 4.7 nF,
  • 10 nF, 22 nF, 47 nF,
  • 100 nF, 220 nF, 470 nF,
  • 1 μF, 2.2 μF, 4.7 μF,
  • 10 μF, 22 μF, 47 μF,
  • 100 μF, 220 μF, 470 μF,
  • 1000 μF, 2200 μF, 4700 μF,
  • 10000 μF
  • 1.0 pF, 1.5 pF, 2.2 pF, 3.3 pF, 4.7 pF, 6.8 pF,
  • 10 pF, 15 pF, 22 pF, 33 pF, 47 pF, 68 pF,
  • 100 pF, 150 pF, 220 pF, 330 pF, 470 pF, 680 pF,
  • 1 nF, 1.5 nF, 2.2 nF, 3.3 nF, 4.7 nF, 6.8 nF,
  • 10 nF, 15 nF, 22 nF, 33 nF, 47 nF, 68 nF,
  • 100 nF, 150 nF, 220 nF, 330 nF, 470 nF, 680 nF,
  • 1 μF, 1.5 μF, 2.2 μF, 3.3 μF, 4.7 μF, 6.8 μF,
  • 10 μF, 15 μF, 22 μF, 33 μF, 47 μF, 68 μF,
  • 100 μF, 150 μF, 220 μF, 330 μF, 470 μF, 680 μF,
  • 1000 μF, 1500 μF, 2200 μF, 3300 μF, 4700 μF, 6800 μF,
  • 10000 μF

Lists

A decade of the E12 values shown with their electronic color codes on resistors.

List of values for each E series:[nb 1]

E3 values
(40% tolerance)
1.0, 2.2, 4.7
E6 values
(20% tolerance)
1.0, 1.5, 2.2, 3.3, 4.7, 6.8
E12 values
(10% tolerance)
1.0, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2
E24 values
(5% tolerance)
1.0, 1.1, 1.2, 1.3, 1.5, 1.6, 1.8, 2.0, 2.2, 2.4, 2.7, 3.0, 3.3, 3.6, 3.9, 4.3, 4.7, 5.1, 5.6, 6.2, 6.8, 7.5, 8.2, 9.1
E48 values
(2% tolerance)
1.00, 1.05, 1.10, 1.15, 1.21, 1.27, 1.33, 1.40, 1.47, 1.54, 1.62, 1.69, 1.78, 1.87, 1.96, 2.05, 2.15, 2.26, 2.37, 2.49, 2.61, 2.74, 2.87, 3.01, 3.16, 3.32, 3.48, 3.65, 3.83, 4.02, 4.22, 4.42, 4.64, 4.87, 5.11, 5.36, 5.62, 5.90, 6.19, 6.49, 6.81, 7.15, 7.50, 7.87, 8.25, 8.66, 9.09, 9.53
E96 values
(1% tolerance)
1.00, 1.02, 1.05, 1.07, 1.10, 1.13, 1.15, 1.18, 1.21, 1.24, 1.27, 1.30, 1.33, 1.37, 1.40, 1.43, 1.47, 1.50, 1.54, 1.58, 1.62, 1.65, 1.69, 1.74, 1.78, 1.82, 1.87, 1.91, 1.96, 2.00, 2.05, 2.10, 2.15, 2.21, 2.26, 2.32, 2.37, 2.43, 2.49, 2.55, 2.61, 2.67, 2.74, 2.80, 2.87, 2.94, 3.01, 3.09, 3.16, 3.24, 3.32, 3.40, 3.48, 3.57, 3.65, 3.74, 3.83, 3.92, 4.02, 4.12, 4.22, 4.32, 4.42, 4.53, 4.64, 4.75, 4.87, 4.99, 5.11, 5.23, 5.36, 5.49, 5.62, 5.76, 5.90, 6.04, 6.19, 6.34, 6.49, 6.65, 6.81, 6.98, 7.15, 7.32, 7.50, 7.68, 7.87, 8.06, 8.25, 8.45, 8.66, 8.87, 9.09, 9.31, 9.53, 9.76
E192 values
(0.5% and lower tolerance)
1.00, 1.01, 1.02, 1.04, 1.05, 1.06, 1.07, 1.09, 1.10, 1.11, 1.13, 1.14, 1.15, 1.17, 1.18, 1.20, 1.21, 1.23, 1.24, 1.26, 1.27, 1.29, 1.30, 1.32, 1.33, 1.35, 1.37, 1.38, 1.40, 1.42, 1.43, 1.45, 1.47, 1.49, 1.50, 1.52, 1.54, 1.56, 1.58, 1.60, 1.62, 1.64, 1.65, 1.67, 1.69, 1.72, 1.74, 1.76, 1.78, 1.80, 1.82, 1.84, 1.87, 1.89, 1.91, 1.93, 1.96, 1.98, 2.00, 2.03, 2.05, 2.08, 2.10, 2.13, 2.15, 2.18, 2.21, 2.23, 2.26, 2.29, 2.32, 2.34, 2.37, 2.40, 2.43, 2.46, 2.49, 2.52, 2.55, 2.58, 2.61, 2.64, 2.67, 2.71, 2.74, 2.77, 2.80, 2.84, 2.87, 2.91, 2.94, 2.98, 3.01, 3.05, 3.09, 3.12, 3.16, 3.20, 3.24, 3.28, 3.32, 3.36, 3.40, 3.44, 3.48, 3.52, 3.57, 3.61, 3.65, 3.70, 3.74, 3.79, 3.83, 3.88, 3.92, 3.97, 4.02, 4.07, 4.12, 4.17, 4.22, 4.27, 4.32, 4.37, 4.42, 4.48, 4.53, 4.59, 4.64, 4.70, 4.75, 4.81, 4.87, 4.93, 4.99, 5.05, 5.11, 5.17, 5.23, 5.30, 5.36, 5.42, 5.49, 5.56, 5.62, 5.69, 5.76, 5.83, 5.90, 5.97, 6.04, 6.12, 6.19, 6.26, 6.34, 6.42, 6.49, 6.57, 6.65, 6.73, 6.81, 6.90, 6.98, 7.06, 7.15, 7.23, 7.32, 7.41, 7.50, 7.59, 7.68, 7.77, 7.87, 7.96, 8.06, 8.16, 8.25, 8.35, 8.45, 8.56, 8.66, 8.76, 8.87, 8.98, 9.09, 9.20, 9.31, 9.42, 9.53, 9.65, 9.76, 9.88

Table

E-series values, 1.0–2.13
E3 E6 E12 E24 E48 E96 E192
1.0 1.0 1.0 1.0 1.00 1.00 1.00
1.01
1.02 1.02
1.04
1.05 1.05 1.05
1.06
1.07 1.07
1.09
1.1 1.10 1.10 1.10
1.11
1.13 1.13
1.14
1.15 1.15 1.15
1.17
1.18 1.18
1.20
1.2 1.2 1.21 1.21 1.21
1.23
1.24 1.24
1.26
1.27 1.27 1.27
1.29
1.30 1.30
1.32
1.3 1.33 1.33 1.33
1.35
1.37 1.37
1.38
1.40 1.40 1.40
1.42
1.43 1.43
1.45
1.5 1.5 1.5 1.47 1.47 1.47
1.49
1.50 1.50
1.52
1.54 1.54 1.54
1.56
1.58 1.58
1.60
1.6 1.62 1.62 1.62
1.64
1.65 1.65
1.67
1.69 1.69 1.69
1.72
1.74 1.74
1.76
1.8 1.8 1.78 1.78 1.78
1.80
1.82 1.82
1.84
1.87 1.87 1.87
1.89
1.91 1.91
1.93
2.0 1.96 1.96 1.96
1.98
2.00 2.00
2.03
2.05 2.05 2.05
2.08
2.10 2.10
2.13
E-series values, 2.15–4.59
E3 E6 E12 E24 E48 E96 E192
2.2 2.2 2.2 2.2 2.15 2.15 2.15
2.18
2.21 2.21
2.23
2.26 2.26 2.26
2.29
2.32 2.32
2.34
2.4 2.37 2.37 2.37
2.40
2.43 2.43
2.46
2.49 2.49 2.49
2.52
2.55 2.55
2.58
2.7 2.7 2.61 2.61 2.61
2.64
2.67 2.67
2.71
2.74 2.74 2.74
2.77
2.80 2.80
2.84
3.0 2.87 2.87 2.87
2.91
2.94 2.94
2.98
3.01 3.01 3.01
3.05
3.09 3.09
3.12
3.3 3.3 3.3 3.16 3.16 3.16
3.20
3.24 3.24
3.28
3.32 3.32 3.32
3.36
3.40 3.40
3.44
3.6 3.48 3.48 3.48
3.52
3.57 3.57
3.61
3.65 3.65 3.65
3.70
3.74 3.74
3.79
3.9 3.9 3.83 3.83 3.83
3.88
3.92 3.92
3.97
4.02 4.02 4.02
4.07
4.12 4.12
4.17
4.3 4.22 4.22 4.22
4.27
4.32 4.32
4.37
4.42 4.42 4.42
4.48
4.53 4.53
4.59
E-series values, 4.64–9.88
E3 E6 E12 E24 E48 E96 E192
4.7 4.7 4.7 4.7 4.64 4.64 4.64
4.70
4.75 4.75
4.81
4.87 4.87 4.87
4.93
4.99 4.99
5.05
5.1 5.11 5.11 5.11
5.17
5.23 5.23
5.30
5.36 5.36 5.36
5.42
5.49 5.49
5.56
5.6 5.6 5.62 5.62 5.62
5.69
5.76 5.76
5.83
5.90 5.90 5.90
5.97
6.04 6.04
6.12
6.2 6.19 6.19 6.19
6.26
6.34 6.34
6.42
6.49 6.49 6.49
6.57
6.65 6.65
6.73
6.8 6.8 6.8 6.81 6.81 6.81
6.90
6.98 6.98
7.06
7.15 7.15 7.15
7.23
7.32 7.32
7.41
7.5 7.50 7.50 7.50
7.59
7.68 7.68
7.77
7.87 7.87 7.87
7.96
8.06 8.06
8.16
8.2 8.2 8.25 8.25 8.25
8.35
8.45 8.45
8.56
8.66 8.66 8.66
8.76
8.87 8.87
8.98
9.1 9.09 9.09 9.09
9.20
9.31 9.31
9.42
9.53 9.53 9.53
9.65
9.76 9.76
9.88

See also

  • Electronic color code – color-code used to indicate the values of axial electronic components, such as resistors, capacitors, inductors, diodes (also see IEC 60062).
  • Geometric progression
  • Preferred number
  • Renard series – used for current rating of electric fuses
  • Three-character marking code for resistors – for (E48/)E96 values (see EIA-96 and IEC 60062:2016)
  • Two-character marking code for capacitors – for (E3/E6/E12/)E24 values (see ANSI/EIA-198-D:1991, ANSI/EIA-198-1-E:1998, ANSI/EIA-198-1-F:2002 and IEC 60062:2016/AMD1:2019)
  • Reference designator

Notes

  1. ↑ 1.0 1.1 1.2 Some part vendors also list an "E1 series" (with only the value "1"). However, this does not appear to have been standardized in any version of the IEC standard.

References

  1. ↑ Chip Resistors – Product catalog. Passive System Alliance (PSA) / Walsin Technology Corp.. August 2018. p. 2. http://www.passivecomponent.com/wp-content/uploads/2018/10/chipR.pdf. Retrieved 2019-03-23. "[…] E1 series resistance: 1 Ω, 10 Ω, 100 Ω, 1000 Ω, 10000 Ω, 100000 Ω […]" 
  2. ↑ Catalog – Capacitors (Condensers). Allied Radio. 1930. p. 139. http://www.alliedcatalogs.com/html/catalogs_additional/1930/hr139.html. Retrieved 2017-07-11. 
  3. ↑ "Catalog – Capacitors (Condensers)". RadioShack. 1940. p. 54. http://www.radioshackcatalogs.com/html/1940/hr054.html. 
  4. ↑ Catalog – Resistors. Allied Radio. 1930. p. 141. http://www.alliedcatalogs.com/html/catalogs_additional/1930/hr141.html. Retrieved 2017-07-11. 
  5. ↑ "Catalog – Resistors". RadioShack. 1940. p. 60. http://www.radioshackcatalogs.com/html/1940/hr060.html. 
  6. ↑ 6.0 6.1 Reference Data for Radio Engineers (1 ed.). Federal Telephone and Radio Corporation (FTR). 1943. pp. 37–38. https://worldradiohistory.com/BOOKSHELF-ARH/Handbooks/Federal-Reference-Data-Radio-Engineers-1st-1943.pdf. Retrieved 2021-09-08.  (NB. This 1943 publication already shows a list of new "preferred values of resistance" following what was adopted by the IEC for standardization since 1948 and later standardized in IEC 63:1952. For comparison, it also lists "old standard resistance values" as follows: 50, 75, 100, 150, 200, 250, 300, 350, 400, 450, 500, 600, 750, 1 k, 1.2 k, 1.5 k, 2 k, 2.5 k, 3 k, 3.5 k, 4 k, 5 k, 7.5 k, 10 k, 12 k, 15 k, 20 k, 25 k, 30 k, 40 k, 50 k, 60 k, 75 k, 100 k, 120 k, 150 k, 200 k, 250 k, 300 k, 400 k, 500 k, 600 k, 750 k, 1 Meg, 1.5 Meg, 2.0 Meg, 3.0 Meg, 4.0 Meg, 5.0 Meg, 6.0 Meg, 7.0 Meg, 8.0 Meg, 9.0 Meg, 10.00 Meg.)
  7. ↑ 7.0 7.1 Reference Data for Radio Engineers (2 ed.). Federal Telephone and Radio Corporation (FTR). 1946. pp. 53–54. http://www.tubebooks.org/Books/FTR_ref_data.pdf. Retrieved 2020-01-03. 
  8. ↑ Catalog – Passives. Jameco Electronics. 2017. pp. 29–41. https://www.jameco.com/Jameco/catalogs/c171/Passives.pdf. Retrieved 2017-07-11. 
  9. ↑ Components Handbook. MIT Radiation Laboratory Series. 17. McGraw-Hill. 1949. p. 38. https://archive.org/details/mit-rad-lab-series-version-3/17%20-%20Components%20Handbook/page/38/mode/2up. 
  10. ↑ "Preferred Numbers". Proceedings of the Institute of Radio Engineers (Institute of Radio Engineers (IRE)) 39 (2): 115. March 1951. doi:10.1109/JRPROC.1951.230759. ISSN 0096-8390. "[…] For example, some years ago, the Radio-Television Manufacturers Association found it desirable to standardize the values of resistors. The ASA Preferred Numbers Standard was considered, but judged not to suit the manufacturing conditions and the buying practices of the resistor field at the moment, whereas a special series of numbers suited better. The special series was adopted and, since it was an official RTMA list, it has been used by later RTMA committees for other applications than resistors, although adopted originally because of seeming advantages for resistors. Ironically, the original advantages have largely disappeared through changes in resistor manufacturing conditions. But the irregular standard remains... […]". 
  11. ↑ 11.0 11.1 11.2 11.3 IEC 60063:1963 – Preferred number series for resistors and capacitors – Amended in accordance with Amendments 1 (1967) and 2 (1977) (2.0 ed.). International Electrotechnical Commission (IEC). 2007. ISBN 978-2-8318-0027-1. https://webstore.iec.ch/publication/486. Retrieved 2017-07-11. "[…] During the discussions of IEC Technical Committee 12: Radio-communication, at the meeting in Stockholm in 1948, it was […] agreed that one of the most urgent items for international standardization was the series of preferred values for resistors and for capacitors up to 0,1 μF. It would have been desirable to standardize for these series the [math]\displaystyle{ \sqrt[10]{10}\!\, }[/math]-system, but […] in several countries the [math]\displaystyle{ \sqrt[12]{10}\!\, }[/math]-system had been adopted […] because of standardization of tolerances at 5, 10 and 20%. As it was not practicable to change the commercial practice in these countries, the [math]\displaystyle{ \sqrt[12]{10}\!\, }[/math]-system was adopted. The Committee expressed regret that […] it was necessary to recommend the [math]\displaystyle{ \sqrt[12]{10}\!\, }[/math]-system, although it would have been more consistent with ISO practice to use the [math]\displaystyle{ \sqrt[10]{10}\!\, }[/math]-system. The proposal for the series E6, E12 and E24 of preferred values was accepted in Paris in 1950 and subsequently published […] In 1957, the British National Committee came forward with a proposal for E48 and E96 series […] as an extension […] discussed in Zürich in 1957 and Stockholm in 1958 […] at The Hague in September 1959 […] in Ulm at […] October 1959 […] for approval under the Six Months' Rule in March 1960 […] it was decided […] in Nice in 1962 that these series should be published […]"  [1]
  12. ↑ 12.0 12.1 IEC 60063:1952 – Series of preferred values and their associated tolerances for resistors and capacitors (1.0 ed.). International Electrotechnical Commission (IEC). 2007. https://webstore.iec.ch/publication/12583. Retrieved 11 July 2017. 
  13. ↑ 13.0 13.1 IEC 60063:2015 – Preferred number series for resistors and capacitors (3.0 ed.). International Electrotechnical Commission (IEC). 2015-03-27. ISBN 978-2-8322-2427-4. https://webstore.iec.ch/publication/22011. Retrieved 2017-07-11.  [2]
  14. ↑ "Standard Values Used in Capacitors, Inductors, and Resistors". Bourns. 2017. http://www.bourns.com/support/technical-articles/standard-values-used-in-capacitors-inductors-and-resistors. 
  15. ↑ "D/CRCW e3 – Standard Thick Film Chip Resistors – Datasheet". Vishay Intertechnology. 2017. http://www.vishay.com/docs/20035/dcrcwe3.pdf. 
  16. ↑ "TNPW e3 – High Stability Thin Film Flat Chip Resistors – Datasheet". Vishay Intertechnology. 2017. http://www.mouser.com/ds/2/427/tnpw_e3-64594.pdf. 

External links

Printable E series tables

es:Números preferentes#Condensadores y resistencias



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