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This thread is spinoff from NewRPL mainthread to prevent further cluttering it. This subject did surface somewhere on page 18 to 20 on the NewRPL main thread (as autumn 2016). http://www.hpmuseum.org/forum/thread-4645-page-20.html

This notation is used atleast on electronics to write the values of atleast resistors and capacitors, usually seen on schematics as 1R2 or 4k7 etc. Most discussion were that where it originates and what are the rules of the system. Note is made that similar writing style is used with the currency cifrão. See: http://www.hpmuseum.org/forum/thread-464...l#pid59655

In internet page http://www.engineering-bachelors-degree....inductors/ (which seems somewhat cluttered copy and paste content) there is picture referred "BS 1852" which in 1970s version supposedly contains this type of notation for resistor and capacitor values. This supposedly BS1852 scan ( direct link to image in internet page mentioned previously http://lh3.googleusercontent.com/-xVb300...imgmax=800) indicates that actually there is no C nor L markings (nor F(arad) or H(enry)) used only R for resistor decimal point in case of unit factor 1.

It still remains a mystery where this system originates (ie. cifrão).

Edit. Marking for thousand, pause etc.
"A History of Mathematical Notations, Volume 1" : Preview pages : https://books.google.fi/books?id=OQZxHpG...3o&f=false
Finally managed to get a copy of the IEC 60062 intl. std.

It distinguishes between quantities in Ohms and in Farads. For resistances (Ohms) it dictates the use of letters: L, R, K, M & G, with weights: \(10^{-3}\), \(10^0\), \(10^3\), \(10^6\) & \(10^9\) respectively. Such letters are used instead of the decimal dot/comma. L meaning \(10^{-3}\) is justified in such std. (instead of m) cause it dictates the use of uppercase letters, and M is already used for \(10^6\).

For capacitances (Farads), the letters used are: p, n, \(\mu\), m & F, with weights: \(10^{-12}\), \(10^{-9}\), \(10^{-6}\), \(10^{-3}\) & \(10^0\) respectively. As with the previous case, such letters replace the decimal dot/comma. \(\mu\) can be replaced by u or even U.
(10-28-2016 12:27 PM)emece67 Wrote: [ -> ]Finally managed to get a copy of the IEC 60062 intl. std.
Somehow, I missed this new thread... When was your version of the standard published? Does it give an explanation why the letter "R" was chosen?

This is what I found out in the meantime:

The first (known) issue of BS 1852 was published in 1975, and it was based on the third issue of IEC 62 in 1974.

The first issue of IEC 62 was published on 1952-01-01, and it already described a so called "color code for fixed resistors" as well as a "letter and digit code for resistance and capacitance values and tolerances". (https://webstore.iec.ch/publication/12579) (Later issues of the standard added a production date code as well.)

The resistor color code defined in IEC 62 is even older than 1952; apparently it was based on a so called "RMA color code" or "RETMA color code" dating back into the early 1920s (RMA and RETMA stand for Radio Manufacturers' Association and Radio Electronics Television Manufacturers' Association, respectively, later part of the Electronic Industries Alliance) and was later standardized in EIA RS-279. This might indicate that the letter and digit code described in IEC 62 had earlier roots as well, although they are still unknown.

In 1973, there also was DIN 40825 defining a value code for resistors and capacitors. Since this (with two other DIN standards) was superseded by DIN IEC 62 in 1985, I assume, that DIN 40825 described the same code already found in earlier issues of IEC 62, but I have not seen the standard myself, therefore I'm not sure about that.
At least in Germany, the code was also known as RKM code.

IEC 62 became IEC 60062 in 1997.

BTW. IEC 60062 was updated to its sixth edition earlier this year, and reportedly this new version contains various additions (including a new color "pink" for the color code, but also in regard to the letter and digit code). This could be quite interesting, but so far I don't know the details.


Really interesting.

I have this one old radioamateur book from 1957 that mentions old colorcode system used in GB and US manufacturers ( with mention that some of them still did use it ). I assume it is one RETMA or the standard system derived from there.

The description of system is as follows (my translation):
"The resistor body color gives the first number, another end of the body have different color and gives the second number and amount of zeros is indicated by the colored dot in the middle of the body. The color and number relation is the same as "Vitrohm uses"." (the same as is used today, Edit. Color indicates number of zeros not multiplier. ..oh, never thought or paid attention before, multiplier of todays system gives same amount of zeros ofcourse since 10^x notation, silly me. ).

For the actual subject I have no further information.
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