What are 6.5 Digit Multimeters Good For?
in [Design]
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From: Jan Panteltje on 13 Mar 2010 08:33 On a sunny day (Fri, 12 Mar 2010 18:37:43 -0600) it happened Jim Yanik <jyanik(a)abuse.gov> wrote in <Xns9D39C7E3AA7F3jyaniklocalnetcom(a)216.168.3.44>: >>>They are not needed, all you need is a 5 Euro multimeter, >>>and in extreme cases a precise reference. >>>That means if you use one of those reference chips, you borrow >>>the very accurate multimeter for a day, measure your reference chip, >>>write it down, and use that to calibrate your cheap multimeter, >>>or o compute it's real value, >>>Saved: 1000$ > >that fails to verify the voltage divider. >the reference would only verify the low range. That is true, but it seems if your read the specs on the expensive ones, then those are sometimes also that accurate on DC only and on limited ranges.
From: John Fields on 13 Mar 2010 09:13 On Sat, 13 Mar 2010 13:27:35 GMT, Jan Panteltje <pNaonStpealmtje(a)yahoo.com> wrote: >On a sunny day (Fri, 12 Mar 2010 13:00:04 -0800) it happened D from BC ><myrealaddress(a)comic.com> wrote in <MPG.26044b27299d843e9896f7(a)209.197.12.12>: > >>In article <hne8fg$uqm$1(a)news.albasani.net>, pNaonStpealmtje(a)yahoo.com >>says... >>> >>> On a sunny day (Fri, 12 Mar 2010 10:50:48 -0600) it happened John Fields >>> <jfields(a)austininstruments.com> wrote in >>> <ekrkp5lg8obtcmftn2tmq8adsnlte9u59e(a)4ax.com>: >>> >>> >On Fri, 12 Mar 2010 12:30:31 GMT, Jan Panteltje >>> ><pNaonStpealmtje(a)yahoo.com> wrote: >>> > >>> >>On a sunny day (Thu, 11 Mar 2010 17:56:35 -0800) it happened D from BC >>> >><myrealaddress(a)comic.com> wrote in <MPG.26033f321480b139896e5(a)209.197.12.12>: >>> >> >>> >>>6.5 digit multimeters sell around $1000.00. >>> >>>For electronics development, are these $1000 multimeters really >>> >>>necessary? >>> >>>What are they good for? >>> >> >>> >>They are not needed, all you need is a 5 Euro multimeter, >>> >>and in extreme cases a precise reference. >>> >>That means if you use one of those reference chips, you borrow >>> >>the very accurate multimeter for a day, measure your reference chip, >>> >>write it down, and use that to calibrate your cheap multimeter, >>> >>or o compute it's real value, >>> >>Saved: 1000$ >>> > >>> >--- >>> >If you don't _need_ the accurate multimeter, then how do you get around >>> >the fact that unless you use _it_ to measure the reference, your cheap >>> >multimeter is pretty much a boat anchor? >>> > >>> > >>> >JF >>> >>> Sorry can you explain that again in electronics English? >> >>He means you still need an accurate tool to make use of a less accurate >>tool. Which raises the question, why have the less accurate tool? >> >>btw... Boat anchor is a term I sometimes use for large heavy antiqued >>test equipment. >>Pre LCD scopes are boat anchors. > >Yes, OK, but Fields did not read very well, >you only need the accurate one ONCE. >And that means you can go to a place and have yor reference measured. --- You seem to be the one having trouble with the language since even if it's used only once, you still _need_ the higher accuracy instrument in order to determine the error in the lower accuracy one. JF
From: John Fields on 13 Mar 2010 09:20 On Sat, 13 Mar 2010 13:17:00 GMT, Jan Panteltje <pNaonStpealmtje(a)yahoo.com> wrote: >On a sunny day (Fri, 12 Mar 2010 15:03:42 -0600) it happened John Fields ><jfields(a)austininstruments.com> wrote in ><8talp59g6d4lma3q6p93ttnnsn4cnm6m71(a)4ax.com>: > >>On Fri, 12 Mar 2010 20:15:16 GMT, Jan Panteltje >><pNaonStpealmtje(a)yahoo.com> wrote: >> >>>On a sunny day (Fri, 12 Mar 2010 09:33:25 -0800) it happened D from BC >>><myrealaddress(a)comic.com> wrote in <MPG.26041ac522f727379896f0(a)209.197.12.12>: >>> >>>>In article <hndc5b$37k$1(a)news.albasani.net>, pNaonStpealmtje(a)yahoo.com >>>>says... >>>>> >>>>> On a sunny day (Thu, 11 Mar 2010 17:56:35 -0800) it happened D from BC >>>>> <myrealaddress(a)comic.com> wrote in <MPG.26033f321480b139896e5(a)209.197.12.12>: >>>>> >>>>> >6.5 digit multimeters sell around $1000.00. >>>>> >For electronics development, are these $1000 multimeters really >>>>> >necessary? >>>>> >What are they good for? >>>>> >>>>> They are not needed, all you need is a 5 Euro multimeter, >>>>> and in extreme cases a precise reference. >>>>> That means if you use one of those reference chips, you borrow >>>>> the very accurate multimeter for a day, measure your reference chip, >>>>> write it down, and use that to calibrate your cheap multimeter, >>>>> or o compute it's real value, >>>>> Saved: 1000$ >>>>> >>>>> Of course there are exceptions, >>>>> but in places where that counts they usually have a lot of ++++expensive stuff anyways. >>>>> Usually places where nothing really useful is done, like in CERN, or ITER, or LIGO, >>>>> etc. >>>> >>>>How about mohm measurements? Maybe that's handy. >>>>My DMM only goes to 0.1 ohm. >>>>I thought of measuring DCR of coils or pcb trace resistance for sim >>>>accuracy. >>> >>>I have a controlled current souce. >>>Stuff 1 A through the .1 resistor and measure the voltage drop? >> >>--- >>And you've determined the accuracy of the current source and the >>resistor, how??? >> >>JF > >The question was not about accuracy, but how to measure .1 Ohm. --- Sidestep, eh? _How_ to measure it is trivial; how to _believe_ that what you measure is right is the essence of the thread. JF
From: John Fields on 13 Mar 2010 09:25 On Sat, 13 Mar 2010 13:23:56 GMT, Jan Panteltje <pNaonStpealmtje(a)yahoo.com> wrote: >On a sunny day (Fri, 12 Mar 2010 15:31:33 -0600) it happened John Fields ><jfields(a)austininstruments.com> wrote in ><a3blp59kk10s93orbunu7mg8s921d1t56f(a)4ax.com>: > >>On Fri, 12 Mar 2010 20:33:42 GMT, Jan Panteltje >><pNaonStpealmtje(a)yahoo.com> wrote: >> >>>On a sunny day (Fri, 12 Mar 2010 10:50:48 -0600) it happened John Fields >>><jfields(a)austininstruments.com> wrote in >>><ekrkp5lg8obtcmftn2tmq8adsnlte9u59e(a)4ax.com>: >>> >>>>On Fri, 12 Mar 2010 12:30:31 GMT, Jan Panteltje >>>><pNaonStpealmtje(a)yahoo.com> wrote: >>>> >>>>>On a sunny day (Thu, 11 Mar 2010 17:56:35 -0800) it happened D from BC >>>>><myrealaddress(a)comic.com> wrote in <MPG.26033f321480b139896e5(a)209.197.12.12>: >>>>> >>>>>>6.5 digit multimeters sell around $1000.00. >>>>>>For electronics development, are these $1000 multimeters really >>>>>>necessary? >>>>>>What are they good for? >>>>> >>>>>They are not needed, all you need is a 5 Euro multimeter, >>>>>and in extreme cases a precise reference. >>>>>That means if you use one of those reference chips, you borrow >>>>>the very accurate multimeter for a day, measure your reference chip, >>>>>write it down, and use that to calibrate your cheap multimeter, >>>>>or o compute it's real value, >>>>>Saved: 1000$ >>>> >>>>--- >>>>If you don't _need_ the accurate multimeter, then how do you get around >>>>the fact that unless you use _it_ to measure the reference, your cheap >>>>multimeter is pretty much a boat anchor? >>>> >>>> >>>>JF >>> >>>Sorry can you explain that again in electronics English? >> >>--- >>If you can't understand it in plain English, what makes you think you'll >>be any less confused in "electronics English", whatever that may be? >> >>The point I was making was that your statement that 6.5 digit >>multimeters aren't needed is wrong, since without one you wouldn't be >>able to determine the accuracy of the cheap multimeter. >> >> >>JF > >I know a guy who was actually a technican, he started studying philoosphy. >He showed mw one of his books. >To make a long story short: Philosophy is not for me. --- The book had an ugly cover? JF
From: Archimedes' Lever on 13 Mar 2010 12:39
On Sat, 13 Mar 2010 13:17:00 GMT, Jan Panteltje <pNaonStpealmtje(a)yahoo.com> wrote: >On a sunny day (Fri, 12 Mar 2010 15:03:42 -0600) it happened John Fields ><jfields(a)austininstruments.com> wrote in ><8talp59g6d4lma3q6p93ttnnsn4cnm6m71(a)4ax.com>: > >>On Fri, 12 Mar 2010 20:15:16 GMT, Jan Panteltje >><pNaonStpealmtje(a)yahoo.com> wrote: >> >>>On a sunny day (Fri, 12 Mar 2010 09:33:25 -0800) it happened D from BC >>><myrealaddress(a)comic.com> wrote in <MPG.26041ac522f727379896f0(a)209.197.12.12>: >>> >>>>In article <hndc5b$37k$1(a)news.albasani.net>, pNaonStpealmtje(a)yahoo.com >>>>says... >>>>> >>>>> On a sunny day (Thu, 11 Mar 2010 17:56:35 -0800) it happened D from BC >>>>> <myrealaddress(a)comic.com> wrote in <MPG.26033f321480b139896e5(a)209.197.12.12>: >>>>> >>>>> >6.5 digit multimeters sell around $1000.00. >>>>> >For electronics development, are these $1000 multimeters really >>>>> >necessary? >>>>> >What are they good for? >>>>> >>>>> They are not needed, all you need is a 5 Euro multimeter, >>>>> and in extreme cases a precise reference. >>>>> That means if you use one of those reference chips, you borrow >>>>> the very accurate multimeter for a day, measure your reference chip, >>>>> write it down, and use that to calibrate your cheap multimeter, >>>>> or o compute it's real value, >>>>> Saved: 1000$ >>>>> >>>>> Of course there are exceptions, >>>>> but in places where that counts they usually have a lot of ++++expensive stuff anyways. >>>>> Usually places where nothing really useful is done, like in CERN, or ITER, or LIGO, >>>>> etc. >>>> >>>>How about mohm measurements? Maybe that's handy. >>>>My DMM only goes to 0.1 ohm. >>>>I thought of measuring DCR of coils or pcb trace resistance for sim >>>>accuracy. >>> >>>I have a controlled current souce. >>>Stuff 1 A through the .1 resistor and measure the voltage drop? >> >>--- >>And you've determined the accuracy of the current source and the >>resistor, how??? >> >>JF > >The question was not about accuracy, but how to measure .1 Ohm. Which one cannot do without a KNOWN source voltage and a KNOWN capacity to read current accurately. |