What are 6.5 Digit Multimeters Good For?
in [Design]
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From: Spehro Pefhany on 12 Mar 2010 16:37 On Fri, 12 Mar 2010 15:31:33 -0600, John Fields <jfields(a)austininstruments.com> wrote: >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 By his logic, you wouldn't need a wife if your neigbor has one.
From: Fred Bartoli on 12 Mar 2010 16:50 Spehro Pefhany a �crit : > On Fri, 12 Mar 2010 15:31:33 -0600, John Fields > <jfields(a)austininstruments.com> wrote: > >> 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 > > By his logic, you wouldn't need a wife if your neigbor has one. > But I sure wouldn't use the $5 wife, even if I had the million dollars baby to compare against... -- Thanks, Fred.
From: John Fields on 12 Mar 2010 17:30 On Fri, 12 Mar 2010 16:37:29 -0500, Spehro Pefhany <speffSNIP(a)interlogDOTyou.knowwhat> wrote: >On Fri, 12 Mar 2010 15:31:33 -0600, John Fields ><jfields(a)austininstruments.com> wrote: > >>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 > >By his logic, you wouldn't need a wife if your neigbor has one. --- How sad, though, if you had a cheap one and found out how woefully inadequate she was by comparing her with your neighbor's classy one. ;) JF
From: John Larkin on 12 Mar 2010 18:23 On Fri, 12 Mar 2010 10:24:06 -0800, "Joel Koltner" <zapwireDASHgroups(a)yahoo.com> wrote: >"John Larkin" <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in message >news:mh0lp5t4e1abliki9ra07qgrpb9q56ej6k(a)4ax.com... >> It's interesting to calculate the resistance of traces and actually >> measure them. Most pcb houses skimp on plating, so when you specify "1 >> oz" copper, you seldom get it. > >I figured that it's a somewhat open-loop process where they stick your board >in a tank and set a timer (based on calculations of their chemistry and the >size of your board) so it's probably no better than +/-20%... and apparently >many customers aren't really relying on the spec anyway so only a few places >bother measuring it for you. Except that you never get too much copper... always too little. John
From: Jamie on 12 Mar 2010 19:47
Jon Slaughter wrote: > John Larkin wrote: > >> On Thu, 11 Mar 2010 17:56:35 -0800, D from BC >> <myrealaddress(a)comic.com> wrote: >> >>> 6.5 digit multimeters sell around $1000.00. >>> For electronics development, are these $1000 multimeters really >>> necessary? >>> What are they good for? >> >> >> Measuring to PPM accuracy, and measuring microvolt-level voltages. And >> as a traceable standard for calibrating products. >> >> The Fluke 8845A is excellent. >> >> John > > > What's the big deal? Can't they just switch to 24-bit ADC's on the cheap > and get the accuracy? Or is there some special techniques required to > get that resolution in practice? resolution, stability, linearity, certification etc.. |