In message <e6acec5be8405b4e936c9e9bccac10241b6...@bb-corp-be1.corp.cubic.cub>, dated Wed, 14 Mar 2007, "Price, Ed" <ed.pr...@cubic.com> writes:
>BTW, does anyone know when component manufacturers started using this >tolerance progression? From my own observation, the system was in place >for 1930's era design. Was it codified under some old EIA standard, or >is it even older? Radio(tron) Designer's Handbook is usually good for antediluvian references, but Chapter 38 doesn't have any before WWII. My recollection of examining (cannibalizing) British armed forces equipment after WWII is that at the beginning of WWII (TR9 set), preferred value resistors were not in use, but they were very soon after the beginning, probably as a result of a Ministry of Supply or War Office edict. An article in 'Wireless World' on the subject certainly gives the impression that the principle, anyway, had been adopted in UK before 1939. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk There are benefits from being irrational - just ask the square root of 2. John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.org Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________
