Precisely. You do not get a normal distribution around the target value,
because the closer each resistor is to the target value, the more valuable
it becomes as a higher tolerance resistor.
> From: Robert Johnson
> Organization: ITE Safety
> Date: Tue, 13 Mar 2007 23:33:27 -0500
> To: ted.eck..
Do I assume this means that a 10% 1K resistor will have values between
900 and 950 ohms or between 1050 and 1100 ohms since the resistors
measuring between 950 and 1050 will have been placed in the 5% or better
stock?
Bob Johnson
ted.eck...@apcc.com wrote:
> The standard resistor values are sel
Brian -
I reread your post and see I may have misunderstood your question. The
statement you cited was in a UL report or in a Recognition Card? If in
a report, it is utterly useless and is an example of poor report
writing. Not quite useless if it was in a Recognition Card, since it
would se
> From: Brian O'Connell
> Sent: Tuesday, March 13, 2007 12:48 PM
>
> In an OBMW2 (UL) file, this comment is attached to one of the
> wire types:
>
> "Additional consideration is needed before its use in
> System's thermal aging."
>
Brian -
Looks like it's a catch-all flag. It doesn't appear
Good day
Does anyone know where I can find Regulatory Information for marketing and
importing, Disk Storage Arrays into Central and South American Countries, plus
the Caribbean nations?
Regards
Roger Anderson
EqualLogic, Inc.
9 Townsend West
Nashua, NH 03063
U.S.A.
Phone 1-603-249-
In an OBMW2 (UL) file, this comment is attached to one of the wire types:
"Additional consideration is needed before its use in System's thermal
aging."
While I am waiting for the usual 5 to 20 day reply time from an agency
engineer, could someone please advise if this means anything speacil to
i
From: John Woodgate [mailto:j...@jmwa.demon.co.uk]
Sent: Tuesday, March 13, 2007 9:20 AM
To: emc-p...@ieee.org
Subject: Re: OT: standard component values
In message
,
dated Tue, 13 Mar 2007, "Tarver, Peter"
writes:
>Or maybe there's a mathematical reason that hasn't occurred to me, like
>some
Determine installation environment, measure Working V, add I.T. safety
standard, stir well.
For a SMPS, only the MINIMUM creepage is determined by the rated input V;
otherwise is determined by empirical measurements of the WV across a
particular dim.
"60950:1999" is obsolete.
R/S,
Brian
> -
> From: Amund Westin
> Sent: Tuesday, March 13, 2007 10:13 AM
> Interested in creepage distances
> 1) primary to secondary on the PBC
> 2) Primary to chassis
> 3) Secondary to chassis
> 4) Between primary leads on the PCB
>
> I have the 60950:1999 in front of me and a lot of "creepage
> tables" i
Trying to find out the different required creepage distances on a PCB (it's
an AC/DC PSU) where the primary voltage is 230VAC avd secondary voltage is
24VDC.
Interested in creepage distances
1) primary to secondary on the PBC
2) Primary to chassis
3) Secondary to chassis
4) Between primary leads o
In message ,
dated Tue, 13 Mar 2007, "Powell, Doug" writes:
>Years ago, I even had a program for my HP-67 calculator that would take
>a desired value and show me the nearest standard value.
There is a small app at:
http://www.miscel.dk/MiscEl/miscel.html
which does a lot more than that. I'm
In message
,
dated Tue, 13 Mar 2007, "Tarver, Peter"
writes:
>Or maybe there's a mathematical reason that hasn't occurred to me, like
>some arithmetic progression, or even simple phobias or prejudices.
Ah, you youngsters! (Strokes long, white beard.)
It's based on geometric progression and
Dave,
You are correct. Years ago the Electronic Industries Association (EIA),
devised a system and applied to resistors and capacitors. There is a
mathematical algorithm based on the E-Series numbers.
E6 20%
E12 10%
E24 5%
E48 2%
E96 1%
E1920.5, 0.25, 0.1%
Years ag
http://www.pc-control.co.uk/resistor-eia.htm
Regards,
Chris
From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of David
Cuthbert
Sent: 13 March 2007 15:38
To: 'Tarver, Peter'; 'PSTC 1'
Subject: RE: standard component values
Quote: "These values were supposed to have been derived f
Resistor/capacitor values are set up so that the ratio of any two
consecutive values is roughly twice the tolerance. This is per any number
of standards, all of which may be obsolete: USA Standard C83.2 (likely ANSI
now), EIA GEN 102, IEC Publication 63. The actual multipliers are slightly
diffe
Take E12 series - 12 values based on 10^1/12 = 1.212 - you calculate the next
value by multiplying the last by this number 1.212 and rounding thus:
1.0
1.0 x 1.212 = 1.2
1.212 x 1.212 = 1.47 = 1.5
1.47 x 1.212 = 1.78 = 1.8
Regards,
Chris
From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]
Peter,
My understanding is that each series, E12, E24, etc increments approximately
according to the corresponding tolerance such that adjacent values
approximately meet at the upper tolerance of one value and the lower
tolerance of the next greater value. This is rounded off to the nearest
intege
The standard resistor values are selected to ensure that any resistor
manufactured can be marked as a valid part and sold. For 5% resistors,
each value is approximately 10% larger than the previous value. Anything
between 9.5 and 10.5 could be called 10 within 5%. Likewise, the 1%
resistor value
Quote: "These values were supposed to have been derived from the
mathematical series of equally spacing values logarithmically for each
decade."
http://www.eng-tips.com/viewthread.cfm?qid=71035&page=5
Dave Cuthbert
Linear Technology
From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On B
An off-topic question that hopefully someone can shed a little light
upon.
I have wondered for as long as I've been involved in things electrical,
why standard component values are what they are. Text books are of no
use and I've done more than a few internet searches on this in the last
ten year
To Those Who are Interested in:
The following two standards took effect March 1, 2007.
GB 7251.2-2006 ( IEC 60439-2:2000)
低压成套开关设备和控制设备
第2部分：对母线干线系统(母线槽)的特殊要求
Low-voltage switchgear and controlgear assemblies—Part 2:Particular
requirements for busbar trunking systems (busways)
GB 725
In message
, dated Mon, 12 Mar 2007, Richard Pittenger
writes:
> I assume that some of you are involved with products such as
>back-lit LCD displays which use small fluorescent lamps for
>back-lighting. I'm working on a product that will be imported to the
>USA and it uses such a disp
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