Re: [time-nuts] OT Prototype Boards
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 from using british definitions to metric definitions the rule, those making the 1866 metric act only the translation table to the now derivate unit of US Inch, as opposed to the later defined international inch. What a mess, what a mess. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Prototype Boards
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... 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 from using british definitions to metric definitions the rule, those making the 1866 metric act only the translation table to the now derivate unit of US Inch, as opposed to the later defined international inch. What a mess, what a mess. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Prototype Boards
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 international foot was defined in 1959, a great deal of survey data was already available based on the former definitions, especially in the United States and in India. The small difference between the survey and the international foot would not be detectable on a survey of a small parcel, but becomes significant for mapping, or when the state plane coordinate system is used in the US, because the origin of the system may be hundreds of thousands of feet (hundreds of miles) from the point of interest. Hence the previous definitions continued to be used for surveying in the United States and India for many years, and are denoted survey feet to distinguish them from the international foot. The United Kingdom was unaffected by this problem, as the retriangulation of Great Britain (1936-62) had been done in meters. The United States survey foot is defined as exactly 1200/3937 meter, approximately 0.3048006096 m.[ -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Prototype Boards
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 IS (present tense) one, defined as 2.54 cm. Except... http://en.wikipedia.org/wiki/Foot_%28unit%29#International_foot When the international foot was defined in 1959, a great deal of survey data was already available based on the former definitions, especially in the United States and in India. The small difference between the survey and the international foot would not be detectable on a survey of a small parcel, but becomes significant for mapping, or when the state plane coordinate system is used in the US, because the origin of the system may be hundreds of thousands of feet (hundreds of miles) from the point of interest. Hence the previous definitions continued to be used for surveying in the United States and India for many years, and are denoted survey feet to distinguish them from the international foot. The United Kingdom was unaffected by this problem, as the retriangulation of Great Britain (1936-62) had been done in meters. The United States survey foot is defined as exactly 1200/3937 meter, approximately 0.3048006096 m.[ -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Prototype Boards
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) 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 international foot was defined in 1959, a great deal of survey data was already available based on the former definitions, especially in the United States and in India. The small difference between the survey and the international foot would not be detectable on a survey of a small parcel, but becomes significant for mapping, or when the state plane coordinate system is used in the US, because the origin of the system may be hundreds of thousands of feet (hundreds of miles) from the point of interest. Hence the previous definitions continued to be used for surveying in the United States and India for many years, and are denoted survey feet to distinguish them from the international foot. The United Kingdom was unaffected by this problem, as the retriangulation of Great Britain (1936-62) had been done in meters. The United States survey foot is defined as exactly 1200/3937 meter, approximately 0.3048006096 m.[ -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Prototype Boards
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 system actually /on/ the Greenwich prime meridian - see: http://www.rmg.co.uk/explore/astronomy-and-time/astronomy-facts/history/the-longitude-of-greenwich David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Prototype Boards
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 pinboards. They don't have to be shot in rockets . . . My only bitch currently is with the absurd gaps in the Arduino boards Grr. Don Bob Stewart 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 prototype board sitting around here someplace that is unusable because the pitch isn't quite right. Needless to say, I'm ordering this from ebay from a seller in China or Hong Kong or someplace, points East. Bob - AE6RV ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind. De Erroribus Medicorum, R. Bacon, 13th century. If you don't know what it is, don't poke it. Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 Skype: buffler2 www.lightningforensics.com www.sixmilesystems.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
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 can't find it, so it must be in a landfill, but it was just exactly the wrong size to fit a chip. You could get the first few pins in, but then the differences would be enough that no more would fit. Bob - Original Message - From: Orin Eman orin.e...@gmail.com To: Discussion of precise time and frequency measurement 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... if it is, you should be fine with 0.1 pitch chips. Orin. On Mon, Jun 24, 2013 at 9:10 PM, Bob Stewart b...@evoria.net wrote: 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 prototype board sitting around here someplace that is unusable because the pitch isn't quite right. Needless to say, I'm ordering this from ebay from a seller in China or Hong Kong or someplace, points East. Bob - AE6RV ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Prototype Boards
It's not 'industry'. It's the international standards agency, whatever it's called. The folks that define a meter as some number of wavelengths of light in vacuo and so on. There are some early perf boards that have holes on 1/16 centers, for use w/flea clips'. -John === 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 it, so it must be in a landfill, but it was just exactly the wrong size to fit a chip. You could get the first few pins in, but then the differences would be enough that no more would fit. Bob - Original Message - From: Orin Eman orin.e...@gmail.com To: Discussion of precise time and frequency measurement 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... if it is, you should be fine with 0.1 pitch chips. Orin. On Mon, Jun 24, 2013 at 9:10 PM, Bob Stewart b...@evoria.net wrote: 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 prototype board sitting around here someplace that is unusable because the pitch isn't quite right. Needless to say, I'm ordering this from ebay from a seller in China or Hong Kong or someplace, points East. Bob - AE6RV ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Prototype Boards
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 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 it, so it must be in a landfill, but it was just exactly the wrong size to fit a chip. You could get the first few pins in, but then the differences would be enough that no more would fit. Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Prototype Boards
Maybe it was a 2 mm pitch, a somewhat common size. Others that come to mind are 0.125 and 0.156 inches. Tom - Original Message - From: Bob Stewart b...@evoria.net To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Tuesday, June 25, 2013 10:03 AM 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 can't find it, so it must be in a landfill, but it was just exactly the wrong size to fit a chip. You could get the first few pins in, but then the differences would be enough that no more would fit. Bob - Original Message - From: Orin Eman orin.e...@gmail.com To: Discussion of precise time and frequency measurement 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... if it is, you should be fine with 0.1 pitch chips. Orin. On Mon, Jun 24, 2013 at 9:10 PM, Bob Stewart b...@evoria.net wrote: 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 prototype board sitting around here someplace that is unusable because the pitch isn't quite right. Needless to say, I'm ordering this from ebay from a seller in China or Hong Kong or someplace, points East. Bob - AE6RV ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Prototype Boards
Brent, I seem to remember a story about the early days of micro-computing, when Russia was cloning 8080 chips. Their chips were of such poor quality that each chip had a unique list of executions that could not be used. Anyway, the Russians had sized their chip in metric measurements (2.54mm) 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 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 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Prototype Boards
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 Circuit Board - you will find plenty. Also - I tend to do point-to-point wiring by soldering 30ga kynar wire wrap wire to the pads. Silver plated - solders well... I have an old pair of flush cutters with a nick in the blade that works perfectly as a wire stripper... ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
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... On 6/25/2013 5:09 PM, J. Forster wrote: It's not 'industry'. It's the international standards agency, whatever it's called. The folks that define a meter as some number of wavelengths of light in vacuo and so on. There are some early perf boards that have holes on 1/16 centers, for use w/flea clips'. -John === 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 it, so it must be in a landfill, but it was just exactly the wrong size to fit a chip. You could get the first few pins in, but then the differences would be enough that no more would fit. Bob - Original Message - From: Orin Emanorin.e...@gmail.com To: Discussion of precise time and frequency measurement 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... if it is, you should be fine with 0.1 pitch chips. Orin. On Mon, Jun 24, 2013 at 9:10 PM, Bob Stewartb...@evoria.net wrote: 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 prototype board sitting around here someplace that is unusable because the pitch isn't quite right. Needless to say, I'm ordering this from ebay from a seller in China or Hong Kong or someplace, points East. Bob - AE6RV ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Prototype Boards
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 it, so it must be in a landfill, but it was just exactly the wrong size to fit a chip. You could get the first few pins in, but then the differences would be enough that no more would fit. I think many many years ago, the metric-inch conversion was slightly off from 25.4 mm/inch, but that was back before PCBs and it was only off a tiny amount. Wikipedia's inch article has a history section: http://en.wikipedia.org/wiki/Inch#Modern_standardisation The (a?) old conversion was 39.37 inches/meter. In 1959, that was changed to 25.4 mm/inch. For those of you reading the surveying discussion, there is still a US Survey inch using 39.37. :) 25.4 mm/inch is 39.370078 inches/meter. That's under 2 ppm from 39.37. A 50 pin connector with 0.1 inch spacing would be off by only 0.001 inch. You could probably see or measure that if you looked carefully, but I doubt if there would be any problems inserting a part. -- I've never had any problems with 0.1 inch spacing. I have seen problems with surface mount parts that were metric at 0.65 or 0.5 mm pitch where somebody rounded off too early. That's easy to do if you look at the drawing and use the inch numbers without realizing that you should be using the metric numbers. I just looked at a couple of data sheets. They omitted the inch numbers for the drawings that were really metric. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Prototype Boards
You are right, I was wrong. The Russian 8080 boards were made with 2.5mm, not 2.54. - Original Message - From: MailLists li...@medesign.ro To: j...@quikus.com; Discussion of precise time and frequency measurement time-nuts@febo.com Cc: Sent: Tuesday, June 25, 2013 10:05 AM 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... ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Prototype Boards
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 using that as the conversion factor online. I don't know where the error came from or why it's quoted so regularly. But, it appears to be the rounded result of taking the reciprocal of a rounded number. Don't machinists use this number for conversion? Thanks for the discussion, everyone. bob - Original Message - From: Hal Murray 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, but that was back before PCBs and it was only off a tiny amount. Wikipedia's inch article has a history section: http://en.wikipedia.org/wiki/Inch#Modern_standardisation The (a?) old conversion was 39.37 inches/meter. In 1959, that was changed to 25.4 mm/inch. For those of you reading the surveying discussion, there is still a US Survey inch using 39.37. :) 25.4 mm/inch is 39.370078 inches/meter. That's under 2 ppm from 39.37. A 50 pin connector with 0.1 inch spacing would be off by only 0.001 inch. You could probably see or measure that if you looked carefully, but I doubt if there would be any problems inserting a part. -- I've never had any problems with 0.1 inch spacing. I have seen problems with surface mount parts that were metric at 0.65 or 0.5 mm pitch where somebody rounded off too early. That's easy to do if you look at the drawing and use the inch numbers without realizing that you should be using the metric numbers. I just looked at a couple of data sheets. They omitted the inch numbers for the drawings that were really metric. -- ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Prototype Boards
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 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. But, it appears to be the rounded result of taking the reciprocal of a rounded number. Don't machinists use this number for conversion? Some years ago in 1959 the inch was re-defined to be exactly 25.4 mm. Before that time the inch was only very close to 24.5 mm But for the last 50+ years 24.5 has been an exact conversion. Likely people who are now 65+ years old where taught something different in school if they were in school befoe 1959 and did not keep up with this. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Prototype Boards
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 couldn't use the 3/16 perf boards. They likely still make 3/16 boards. THey are better for all analog parts where you don't use ICs. Now days the world has gone surface mount and the 0.1 based parts are looking rather over sized. Everything is geting smaller and cheaper. On Mon, Jun 24, 2013 at 9:10 PM, Bob Stewart b...@evoria.net wrote: 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 prototype board sitting around here someplace that is unusable because the pitch isn't quite right. Needless to say, I'm ordering this from ebay from a seller in China or Hong Kong or someplace, points East. Bob - AE6RV ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Prototype Boards
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 the reciprocal. It is, indeed very very close to 25.4. 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. But, it appears to be the rounded result of taking the reciprocal of a rounded number. Don't machinists use this number for conversion? Thanks for the discussion, everyone. bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Prototype Boards
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 Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Prototype Boards
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. It's a definition, not a coincidence. The crucial word in that statement being a :-) -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Prototype Boards
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 on the quality of information out there on the web. I still remember 39.37 inches per meter from early school years. I wonder what grade that was. I don't remember that there were any digits past 39.37 but neither do I remember that there weren't any more. I don't remember any discussion of accuracy back then. My guess is that the conversion charts on the web come from somebody starting with 39.37 rather than 25.4 and being smart enough to do the arithmetic but not sharp enough to understand the accuracy or round-off issues. I wonder how many of them are carried over from before the inch was redefined in 1959 as compared to starting with 39.37. You do have to be more than a little geeky to pay attention to things like this. It's under 2 ppm. My copy of Machinery's Handbook (copyright 1984) says 100 inches is 2,540.0 mm. It also says 0.03937 inch/mm and 25.4 mm/inch with no discussion of the accuracy. At the few ppm level you have to pay attention to temperature. (The wiki page on micrometers discusses temperature and they are only good for 0.0001 inches, 100 ppm.) -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Prototype Boards
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 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. But, it appears to be the rounded result of taking the reciprocal of a rounded number. Don't machinists use this number for conversion? Some years ago in 1959 the inch was re-defined to be exactly 25.4 mm. Before that time the inch was only very close to 24.5 mm But for the last 50+ years 24.5 has been an exact conversion. Likely people who are now 65+ years old where taught something different in school if they were in school befoe 1959 and did not keep up with this. To make it even more interesting there were several flavours (US, Canadian, UK ...)of the inch which all differed by a very small amount. Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Prototype Boards
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 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 inch was used. Yes the length of the inch actally changed. So in theory any ruller or machine tools or micrometer made in work war II era has been wrong for a long time. But fortunately the change was tiny at the 1/10,000th level The lllength of the inch, foot, yard and so on all changed a little over 50 years ago so that we could have exact and easy conversions to and from the rest of the world's units. On Tue, Jun 25, 2013 at 10:52 AM, J. Forster j...@quikus.com wrote: 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. It's a definition, not a coincidence. The crucial word in that statement being a :-) -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Prototype Boards
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 using that as the conversion factor online. I don't know where the error came from or why it's quoted so regularly. But, it appears to be the rounded result of taking the reciprocal of a rounded number. Don't machinists use this number for conversion? Thanks for the discussion, everyone. US Metric Act from 1866: www.nist.gov/pml/wmd/metric/upload/HR-596-Metric-Law-1866.pdf http://lamar.colostate.edu/~hillger/laws/metric-act.html In 1912 C.E. Johansson decided to use 25.4 mm for one inch (at 20 degrees C), for his gauge-sets. That was later agreed internationallly on in 1933, but the US Metric Act remained unchanged, which caused confusion ever since. Interesting article: http://www.changeover.com/metrology.html Anyway, unless you need to use a US Survey feet, 1 inch = 25.4 mm exactly is what you should be using. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Prototype Boards
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 inch was used. Yes the length of the inch actally changed. So in theory any ruller or machine tools or micrometer made in work war II era has been wrong for a long time. But fortunately the change was tiny at the 1/10,000th level The lllength of the inch, foot, yard and so on all changed a little over 50 years ago so that we could have exact and easy conversions to and from the rest of the world's units. On Tue, Jun 25, 2013 at 10:52 AM, J. Forster j...@quikus.com wrote: 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. It's a definition, not a coincidence. The crucial word in that statement being a :-) -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] OT Prototype Boards
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 prototype board sitting around here someplace that is unusable because the pitch isn't quite right. Needless to say, I'm ordering this from ebay from a seller in China or Hong Kong or someplace, points East. Bob - AE6RV ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
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 at 9:10 PM, Bob Stewart b...@evoria.net wrote: 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 prototype board sitting around here someplace that is unusable because the pitch isn't quite right. Needless to say, I'm ordering this from ebay from a seller in China or Hong Kong or someplace, points East. Bob - AE6RV ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Prototype Boards
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 absurd gaps in the Arduino boards Grr. Don Bob Stewart 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 prototype board sitting around here someplace that is unusable because the pitch isn't quite right. Needless to say, I'm ordering this from ebay from a seller in China or Hong Kong or someplace, points East. Bob - AE6RV ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind. De Erroribus Medicorum, R. Bacon, 13th century. If you don't know what it is, don't poke it. Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 Skype: buffler2 www.lightningforensics.com www.sixmilesystems.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT Prototype Boards
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 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 absurd gaps in the Arduino boards Grr. Don Bob Stewart 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 prototype board sitting around here someplace that is unusable because the pitch isn't quite right. Needless to say, I'm ordering this from ebay from a seller in China or Hong Kong or someplace, points East. Bob - AE6RV ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind. De Erroribus Medicorum, R. Bacon, 13th century. If you don't know what it is, don't poke it. Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 Skype: buffler2 www.lightningforensics.com www.sixmilesystems.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
