What are 6.5 Digit Multimeters Good For?
in [Design]
|
From: Jim Yanik on 12 Mar 2010 19:37 John Fields <jfields(a)austininstruments.com> wrote in news: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 $1000 multimeters really >>>necessary? >>>What are they good for? >> >>They are not needed, all you need is a 5 Euro multimeter, >>and in extreme cases a precise reference. >>That means if you use one of those reference chips, you borrow >>the very accurate multimeter for a day, measure your reference chip, >>write it down, and use that to calibrate your cheap multimeter, >>or o compute it's real value, >>Saved: 1000$ that fails to verify the voltage divider. the reference would only verify the low range. > > --- > 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 > -- Jim Yanik jyanik at localnet dot com
From: Jim Yanik on 12 Mar 2010 19:40 D from BC <myrealaddress(a)comic.com> wrote in news: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. > > > > the 6.5 digit lab meters usually have 4-wire ohms measurement; you get a more reliable reading,don't have to worry about lead resistance. -- Jim Yanik jyanik at localnet dot com
From: Jim Yanik on 12 Mar 2010 19:43 D from BC <myrealaddress(a)comic.com> wrote in news:MPG.26044b27299d843e9896f7(a)209.197.12.12: > btw... Boat anchor is a term I sometimes use for large heavy antiqued > test equipment. > Pre LCD scopes are boat anchors. > > Not true. -- Jim Yanik jyanik at localnet dot com
From: D from BC on 12 Mar 2010 19:53 In article <Xns9D39C8D3FC146jyaniklocalnetcom(a)216.168.3.44>, jyanik(a)abuse.gov says... > > D from BC <myrealaddress(a)comic.com> wrote in > news:MPG.26044b27299d843e9896f7(a)209.197.12.12: > > > > btw... Boat anchor is a term I sometimes use for large heavy antiqued > > test equipment. > > > > > Pre LCD scopes are boat anchors. > > > > > > Not true. Yeah.. :P CRT + linear transformer + steel chassis = boat anchor. LCD + smps + plastic box = not boat anchor
From: Michael A. Terrell on 12 Mar 2010 20:08
Dave Platt wrote: > > In article <MPG.260350d8fa1b2c289896e7(a)209.197.12.12>, > D from BC <myrealaddress(a)comic.com> wrote: > > >32 ADC > >http://focus.ti.com/lit/ds/symlink/ads1282.pdf > >$77 at Digikey > >I think that's 10 digit. 2^32 = 4294967296 > >Say full scale is 1V then 1st step is 232picovolts. > >uhuh.. > >I get 1mV fuzz just by shorting out my scope probe! > > *chuckle* > > Some years ago, a guy in one of the audio forums suggested that audio > really ought to be recorded and delivered using 32-bit PCM, "just to > make sure." > > I pointed out that if one were to set the playback amplitude so that a > least-significant-bit signal produced audio at the listening position > equal in power to the random thermal noise of air molecules hitting > the eardrum, a full-scale 32-bit signal would vaporize the power > lines, explode the building and kill the listener :-) Yes, but what's the downside of letting one more audiophool eliminate themselves from the genepool? -- Lead free solder is Belgium's version of 'Hold my beer and watch this!' |