From: "R. Lewis"
Subject: Re: want a list of R value E6 E12 E24 E48 E96
Date: Wed, 13 Nov 2002 22:36:19 -0000
Organization: Nextra UK
References: <3DCC0BE7.BEDAFF5@fanwap.com> <5wnbKyBajC09EwpE@jmwa.demon.co.uk>
NNTP-Posting-Date: Wed, 13 Nov 2002 22:35:26 +0000 (UTC)
X-Newsreader: Microsoft Outlook Express 6.00.2600.0000
"John Woodgate" wrote in message
> I read in sci.electronics.design that R. Lewis
> wrote (in ) about 'want a list of R
> value E6 E12 E24 E48 E96', on Wed, 13 Nov 2002:
> >Are you saying that the values decided for the 20% tol. range - toward 70
> >years ago now and not decided by any logarithmic method - are now
> >logarithmic based even though the values have not changed and, as you
> >pointed out, they do not follow any strict logarithmic progression anyway
> No. Before the logarithmic 'preferred value' series were introduced,
> carbon composition resistors were available in an arithmetical sequence
> of values: 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 7, 7.5, 8, 10, for
> example. That series has 15 values per decade and still has gaps. The
> E12 series has just 12 values per decade and only very small gaps.
No matter what logic is applied, what evidence is available, when someone
believes the original preferred ('bulk') resistor values - not called E6 or
anything similar- came about by consideration of a logarithmic progression,
they will always believe it to be so.
Seems to crop up every 1.5 to 2.2 years.