John,
On 06/25/2013 07:52 PM, J. Forster wrote:
No. It's THE definition... there is only one.
It's not like Pi, which equals 3 for small circles.
Inches comes in many lengths, these are just a little over 2 ppm apart
from each other.
In 1893 the Mendenhall Order had the US shift from
Magnus,
There WERE (past tense) a number of definitions of the inch, ranging from
lines on bars of PtIr to a string of grain kernels.
Now there IS (present tense) one, defined as 2.54 cm.
-John
John,
On 06/25/2013 07:52 PM, J. Forster wrote:
No. It's THE definition...
j...@quikus.com said:
There WERE (past tense) a number of definitions of the inch, ranging from
lines on bars of PtIr to a string of grain kernels.
Now there IS (present tense) one, defined as 2.54 cm.
Except...
http://en.wikipedia.org/wiki/Foot_%28unit%29#International_foot
When the
Oh dear. Please go metric US. Please.
We will help you.
Jim
On 27 June 2013 11:33, Hal Murray hmur...@megapathdsl.net wrote:
j...@quikus.com said:
There WERE (past tense) a number of definitions of the inch, ranging from
lines on bars of PtIr to a string of grain kernels.
Now there
The same issue arises with old callendars. What always happens is the old
units are converted to the current standard. You never see a LASER
wavelength in barlycorns. The current definitions are used and backward
corrected.
-John
==
j...@quikus.com said:
There WERE (past tense)
Oh dear. Please go metric US. Please.
We will help you.
Jim
===
Even being metric (and my own country is shamefully slow in adopting metres
for travel distances and litres for selling e.g. milk), did not stop errors
in setting the zero degree line of the GPS
2.54 mm is DEFINED as 0.1 inch. The conversion is EXACT.
-John
2.54 mm pitch is close enough to the .1 in standard. The through-hole
DIP chips will fit fine. I used to build stuff with .1 in perfboard,
sockets, and wire-wrap but only use a very few glue chips now and
time-nuts@febo.com
Cc:
Sent: Monday, June 24, 2013 11:35 PM
Subject: Re: [time-nuts] OT Prototype Boards
0.1 is 2.54mm by definition these days.
See: http://en.wikipedia.org/wiki/International_yard_and_pound
Now whether the board really is 2.54mm is an entirely different matter
time-nuts@febo.com
Cc:
Sent: Monday, June 24, 2013 11:35 PM
Subject: Re: [time-nuts] OT Prototype Boards
0.1 is 2.54mm by definition these days.
See: http://en.wikipedia.org/wiki/International_yard_and_pound
Now whether the board really is 2.54mm is an entirely different
matter
I once saw a board that was 2.5 mm, which would cause what you
describe. As soon as I figured out what the problem was, in the trash
it went.
Brent
On 6/25/2013 8:03 AM, Bob Stewart wrote:
OK, I see in the wiki that 0.1 is by definition 2.54mm. I was taught it was
2.54001, but that's not
Subject: Re: [time-nuts] OT Prototype Boards
OK, I see in the wiki that 0.1 is by definition 2.54mm. I was taught it was
2.54001, but that's not right, either. But, if industry says that they're
defined as the same, then I'm the one out of date. =) I wonder what was with
that old prototype board. I
) rather than inches
(0.10), so that black market imports of the real thing would not fit.
Bob
- Original Message -
From: Brent Gordon time-n...@adobe-labs.com
To: time-nuts@febo.com
Cc:
Sent: Tuesday, June 25, 2013 9:40 AM
Subject: Re: [time-nuts] OT Prototype Boards
I once
With Glass/Epoxy protoboards being so expensive, I have bought several lots of
a phenolic perf board for prototypes off the web and they have been the most
inexpensive boards I have ever found. I don't feel bad about trashing failed
prototypes.. Search your favorite site for 7x9cm PCB Blank
: Re: [time-nuts] OT Prototype Boards
0.1 is 2.54mm by definition these days.
See: http://en.wikipedia.org/wiki/International_yard_and_pound
Now whether the board really is 2.54mm is an entirely different
matter...
if it is, you should be fine with 0.1 pitch chips.
Orin.
On Mon, Jun 24, 2013
b...@evoria.net said:
OK, I see in the wiki that 0.1 is by definition 2.54mm. I was taught it
was 2.54001, but that's not right, either. But, if industry says that
they're defined as the same, then I'm the one out of date. =) I wonder
what was with that old prototype board. I can't find
Subject: Re: [time-nuts] OT Prototype Boards
In the eastern block the customary pitch was exactly 2.5mm. At least
SSSR and DDR ICs were made so. For DIP40s it was a little of a stretch
(read pin bending) job to get them fit on .1 spaced boards
hmur...@megapathdsl.net
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Cc:
Sent: Tuesday, June 25, 2013 10:53 AM
Subject: Re: [time-nuts] OT Prototype Boards
I think many many years ago, the metric-inch conversion was slightly off from
25.4 mm/inch
On Tue, Jun 25, 2013 at 9:17 AM, Bob Stewart b...@evoria.net wrote:
Hi Hal,
I had always used 25.4001 or .03937 to do my conversions. So, I looked
online and found the .039370078 and did the reciprocal. It is, indeed very
very close to 25.4. If you google 25.4001 conversion you can find
Likely you had a very old perf board that was made before the 0.1 spacing
was common. Back in the vacuum tube days the solder strips had tabs on
3/8 centers and layouts were done on multiples of that. And then when the
early through hole chips came out they were on 0.1 centers. And you
Machinists know that 1 inch is exactly 2.54cm or 25.4mm. It's a
definition, not a coincidence.
-Bob
On Tue, Jun 25, 2013 at 10:17 AM, Bob Stewart b...@evoria.net wrote:
Hi Hal,
I had always used 25.4001 or .03937 to do my conversions. So, I looked
online and found the .039370078 and did
In message caf_se-av85uzwvkp2zeil10dcdeohroj0wne1d-13vawcwt...@mail.gmail.com
, Robert Darlington writes:
Machinists know that 1 inch is exactly 2.54cm or 25.4mm. It's a
definition, not a coincidence.
The crucial word in that statement being a :-)
--
Poul-Henning Kamp | UNIX since Zilog
No. It's THE definition... there is only one.
It's not like Pi, which equals 3 for small circles.
-John
===
In message
caf_se-av85uzwvkp2zeil10dcdeohroj0wne1d-13vawcwt...@mail.gmail.com
, Robert Darlington writes:
Machinists know that 1 inch is exactly 2.54cm or 25.4mm.
b...@evoria.net said:
If you google 25.4001 conversion you can find lots of tables using that as
the conversion factor online. I don't know where the error came from or why
it's quoted so regularly.
Thanks. I never would have thought to search for 25.4001. That's an amazing
calibration
Chris Albertson wrote:
On Tue, Jun 25, 2013 at 9:17 AM, Bob Stewartb...@evoria.net wrote:
Hi Hal,
I had always used 25.4001 or .03937 to do my conversions. So, I looked
online and found the .039370078 and did the reciprocal. It is, indeed very
very close to 25.4. If you google 25.4001
It was a JOKE!!!
And, in fact, pi IS a definition: the ratio of the circumferance to the
diameter of a circle - whether it's measured in cubits, furlongs,
nanometers, or light years.
-John
==
Your pi example does not work. Pi is not a definition. the length of
an inch has
Hi Bob,
On 06/25/2013 06:17 PM, Bob Stewart wrote:
Hi Hal,
I had always used 25.4001 or .03937 to do my conversions. So, I looked online and found
the .039370078 and did the reciprocal. It is, indeed very very close to 25.4. If you
google 25.4001 conversion you can find lots of tables
Your pi example does not work. Pi is not a definition. the length of
an inch has changed many times over the centuries so there have been many
definitions. So yes 2.54 mm is the current definition but there are others
and you only have to go mack to 1958 to find that another definition of the
I need to get some largish prototype boards for my project. Has the industry
standardized on a 0.10 pitch for hole spacing? IOW, if the ad says 2.54mm
pitch will I get a board that will fit American chips, or will I just get
something metric sized for the landfill? I ask, because I've got a
0.1 is 2.54mm by definition these days.
See: http://en.wikipedia.org/wiki/International_yard_and_pound
Now whether the board really is 2.54mm is an entirely different matter...
if it is, you should be fine with 0.1 pitch chips.
Orin.
On Mon, Jun 24, 2013 at 9:10 PM, Bob Stewart
2.54 mm pitch is close enough to the .1 in standard. The through-hole
DIP chips will fit fine. I used to build stuff with .1 in perfboard,
sockets, and wire-wrap but only use a very few glue chips now and
pinboards. They don't have to be shot in rockets . . .
My only bitch currently is with the
2.54 mm is exactly 0.1 inch.
Tom
- Original Message -
From: Don Latham d...@montana.com
To: Bob Stewart b...@evoria.net; Discussion of precise time and
frequency measurement time-nuts@febo.com
Sent: Tuesday, June 25, 2013 12:37 AM
Subject: Re: [time-nuts] OT Prototype Boards
2.54
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