What are 6.5 Digit Multimeters Good For?
in [Design]
|
From: Jan Panteltje on 12 Mar 2010 15:15 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?
From: Jan Panteltje on 12 Mar 2010 15:19 On a sunny day (Fri, 12 Mar 2010 09:19:04 -0800) it happened John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in <2jtkp5l6640dtc9b5tujet830kbqtap7i4(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 $1000 multimeters really >>>necessary? >>>What are they good for? >> >>They are not needed, all you need is a 5 Euro multimeter, >>and in extreme cases a precise reference. > >Does your e5 multimeter resolve microvolts? If not, it's useless for >designing thermocouple stuff. Use a LM335, faster, cheaper, better :-) >Can it measure resistance to 0.02%? That >is useful too. For what? >If all you do is muck around with uPs that have 8 bit ADCs, a cheap >meter is almost good enough. > >One cool thing to do with a good DVM is measure voltage drops in PCB >traces and planes, often microvolts. That answers the eternal >question. "where is the damned current going?" I judt answered that to somebody else, use a controlled current source to measure low resistance. It is super simple to make little opamp tool that allows you to probe 2 points on a PCB, takes five minutes to solder together, and have some gain to connect it to your 5 Euro meter, you only need difference, no need for big accuracy in that case. >John > >
From: Jan Panteltje on 12 Mar 2010 15:23 On a sunny day (Fri, 12 Mar 2010 17:56:07 +0100) it happened Fred Bartoli <myname_with_a_dot_inbetween(a)free.fr> wrote in <hndrkn$k3q$1(a)speranza.aioe.org>: >Jan Panteltje a �crit : >> 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 $1000 multimeters really >>> necessary? > >Depends on what you're doing (just got a 8.5 digits 3458A) > >>> What are they good for? >> > >Calibrate my 6.5 and 7.5 digits DMM? And few other things too... > > >> They are not needed, all you need is a 5 Euro multimeter, >> and in extreme cases a precise reference. >> That means if you use one of those reference chips, you borrow >> the very accurate multimeter for a day, measure your reference chip, >> write it down, and use that to calibrate your cheap multimeter, >> or o compute it's real value, >> Saved: 1000$ >> >> 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. >> > >Trying to imply that since you have nothing more than a $5 DMM you're >doing useful things? >Then trash all your tools and you'll get really important... Well, I dunno, I have met people who first thing wanted to stuff the lab with lots of super expensive stuff. Sort of an ego trip. It impresses customers perhaps, but not me. What you do with it counts. There is an old saying: A good musician can play wonderful music on a child's flute. The beginner can not get a decent note out of a Stradivarius. Always remember that, my quote, I came up with it (bangs chest, ego sound LOL). It is so true. >-- >Thanks, >Fred. >
From: Jan Panteltje on 12 Mar 2010 15:33 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?
From: D from BC on 12 Mar 2010 15:43
In article <hne7cu$st1$1(a)news.albasani.net>, pNaonStpealmtje(a)yahoo.com says... > > I have a controlled current souce. > Stuff 1 A through the .1 resistor and measure the voltage drop? Huh..My power supply does have constant I mode.. I'll try that someday. |