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university:courses:electronics:electronics-lab-resistors [04 Jan 2013 16:37] – created Doug Merceruniversity:courses:electronics:electronics-lab-resistors [17 Mar 2024 10:36] (current) – Missing Ω Michele Zaffalon
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 **Understanding the differences between available resistor types and how to select the right one.** **Understanding the differences between available resistor types and how to select the right one.**
  
-Frist we will discuss the familiar "discrete" or axial-lead type resistors we are used to working with in the lab; then we will compare cost and performance tradeoffs of the discrete versions and thin- or thick-film networks.+First we will discuss the familiar "discrete" or axial-lead type resistors we are used to working with in the lab; then we will compare cost and performance tradeoffs of the discrete versions and thin- or thick-film networks.
  
 **Axial Lead Types:** **Axial Lead Types:**
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 Table 1. Standard resistor values: 2%, 5% and 10% Table 1. Standard resistor values: 2%, 5% and 10%
  
-Carbon-type resistors use color-coded bands to identify the resistor's ohmic value and tolerance:+Carbon-type resistors use color-coded bands to identify the resistor's ohmic value and tolerance: (For more on the resistor color code see the section below "A brief history of the resistor color code")
  
 {{ :university:courses:electronics:arn_f1.jpg?300 |}} {{ :university:courses:electronics:arn_f1.jpg?300 |}}
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 <WRAP centeralign> Table 2. Resistor Color code </WRAP>  <WRAP centeralign> Table 2. Resistor Color code </WRAP> 
  
-• Metal film resistors are chosen for precision applications where initial accuracy, low temperature coefficient, and lower noise are required. Metal film resistors are generally composed of Nichrome, tin oxide or tantalum nitride, and are available in either a hermetically sealed or molded phenolic body. Typical applications include bridge circuits, RC oscillators and active filters. Initial accuracies range from 0.1 to 1.0 %, with temperature coefficients ranging between 10 and 100 ppm/°C. Standard values range from 10.0 ? to 301 k? in discrete increments of 2% (for 0.5% and 1% rated tolerances).+• Metal film resistors are chosen for precision applications where initial accuracy, low temperature coefficient, and lower noise are required. Metal film resistors are generally composed of Nichrome, tin oxide or tantalum nitride, and are available in either a hermetically sealed or molded phenolic body. Typical applications include bridge circuits, RC oscillators and active filters. Initial accuracies range from 0.1 to 1.0 %, with temperature coefficients ranging between 10 and 100 ppm/°C. Standard values range from 10.0 Ω to 301 kΩ in discrete increments of 2% (for 0.5% and 1% rated tolerances).
  
 ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^
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 <WRAP centeralign> Figure 10 R/2R resistor ladder </WRAP> <WRAP centeralign> Figure 10 R/2R resistor ladder </WRAP>
 +
 +==== A brief history of the resistor color code: ====
 +
 +The following is excerpted from a mixture of:
 +
 +https://en.wikipedia.org/wiki/Electronic_Industries_Alliance#History\\
 +https://en.wikipedia.org/wiki/Electronic_color_code#History\\
 +https://hsm.stackexchange.com/questions/7096/resistor-color-code\\
 +https://hackaday.com/2020/01/13/why-do-resistors-have-a-color-code/ \\
 +https://www.dailybreak.com/break/cabinet-of-curiosities-why-indigo-is-in-the-rainbow\\
 +https://en.wikipedia.org/wiki/Isaac_Newton's_occult_studies
 +
 +Before industry standards were established (1925), each manufacturer used their own unique system for color coding or marking their components.
 +
 +Then in 1924, 50 radio manufacturers in Chicago formed a trade group. The idea was to share patents among the members. Almost immediately the name changed from “Associated Radio Manufacturers” to the “Radio Manufacturer’s Association” or RMA.
 +
 +The standard color code was developed by the Radio Manufacturers Association (RMA) in the 20’s as a three band code for resistor values. The three bands were more compact than the number value because the third band represented the number of zeroes. Initially the three colors were not three separate bands, and there was no neutral background color. Instead, they were the body color, the tip color and the dot color.
 +
 +{{ :university:courses:electronics:resistor-colors.png?600 |}}
 +
 +Identical adjacent colors were allowed.
 +
 +For example, 250 000 Ω was reduced to three bands. In addition, color bands remained visible in whatever position a resistor was soldered, whereas a stamped number value could be out of sight. The fourth band, representing the tolerance, was added later.
 +
 +[[https://books.google.nl/books?id=VJALAQAAIAAJ&q=%22The%20code%20identifies%20resistors%20by%20means%20of%203%20colors,%20known%20as%20%22body,%22%20%22tip%22%20and%20%22dot%22%20colors%22&dq=%22The%20code%20identifies%20resistors%20by%20means%20of%203%20colors,%20known%20as%20%22body,%22%20%22tip%22%20and%20%22dot%22%20colors%22&hl=en&sa=X&ved=0ahUKEwiGoq-m5cjZAhWCjqQKHQmgBi8Q6AEILTAB|Radio Physics Course, Ghirardi, 1931]]
 +
 +In 1952, it was standardized in IEC 62:1952 by the International Electrotechnical Commission (IEC) and since 1963 also published as EIA RS-279.
 +
 +The sequence of the central group of colors, ROYGBV, was chosen to match the rainbow mnemonic: red-orange-yellow-green-blue-violet, "ROYGBIV", without indigo because most people do not (can not) distinguish, with their eyes, a separate color between blue and violet, plus it’s a little silly color; and is only there because Newton was a little bit of a kook. (Of the rainbow's widely accepted seven colors, three are primary (red, yellow and blue); three are secondary (green, orange and violet) and just one is tertiary (indigo) – When Newton in 1665 named the colors in the rainbow after passing them through a prism – he wanted to the colors in the rainbow to match the 7 notes in a Dorian scale (a scale with no sharps or flats that starts on D), and Newton had a history of dabbling in the occult, and seven is considered a sacred number in the secretive paranormal sciences). The rainbow group is preceded by two low brightness colors, black and brown, representing the lowest digits 0 and 1, and succeeded by two bright colors, grey and white, representing the highest digits 8 and 9.
 +
 +[[https://books.google.nl/books?id=4tkiAAAAMAAJ&redir_esc=y|Electrical Engineering Science, Preston, 1960, p.115]]
 +
 +Color bands were used because they were easily and cheaply printed on tiny components. However, there were drawbacks, especially for color blind people. Overheating of a component or dirt accumulation may make it impossible to distinguish brown from red or orange. Advances in printing technology have now made printed numbers more practical on small components. The values of components in surface mount packages are marked with printed alphanumeric codes instead of a color code.
 +
 +==== For more info on passive components see: ====
 +
 +[[adi>static/imported-files/application_notes/500824934643930414583807523874018494695982855668424783486554001060AN348.pdf|AN-348: Avoiding Passive-Component Pitfalls]]
  
 ** Return to Lab Activity [[university:courses:electronics:labs|Table of Contents]] ** ** Return to Lab Activity [[university:courses:electronics:labs|Table of Contents]] **
  
  
university/courses/electronics/electronics-lab-resistors.1357313832.txt.gz · Last modified: 04 Jan 2013 16:37 by Doug Mercer

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