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matthiaspaul · (This post was last modified: 12-19-2016 07:20 PM by matthiaspaul.)

(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 Since this (with two other DIN standards) was superseded by DIN IEC 62 in 1985, I assume, that DIN 40825 described the same code already found in earlier issues of IEC 62, but I have not seen the standard myself,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.

Greetings,

Matthias