calibrate digital meters

Discussion in 'General Electronics Chat' started by bug13, Dec 4, 2012.

  1. bug13

    Thread Starter Well-Known Member

    Feb 13, 2012
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    so I got a couple cheap Chinese digital meters, I want to see how good they are, is there a nice and easy way to calibrate them? what do you guys usually do?

    I am not looking for professional calibration, just want to know the readings are reasonable acceptable.

    (I know I should buy a fluke :))
     
  2. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    Just measure a known voltage with it..

    For typical hobbyist projects a fluke is just a waste of money and more accuracy/high voltage protection than anyone needs.

    Our flukes are professionally calibrated yearly with proper calibration equipment. NIST Voltage/Current sources. Funny part is most are just used for a simple continuity "beep"... and it costs more to calibrate them than it would be to just buy a new Chinese meter each year..
     
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  3. nsaspook

    AAC Fanatic!

    Aug 27, 2009
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    I think a high quality tool (fluke,hand tools in general) that will last 20+ years and still be as accurate the day it was new is a good investment for any serious hobbyist. I have a 25+ year old Fluke 73 that hasn't been calibrated in 20 years but was still in spec when I checked it with another meter.
    Borrow a calibrated meter and compare the readings with yours.
     
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  4. crutschow

    Expert

    Mar 14, 2008
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    My feeling is that modern multimeters seldom go out of calibration, unless they have been abused. The calibration basically depends upon the stability of the resistors in the unit and that, even for cheap devices, is likely quite good.

    If you have two meters then you can compare one against the other. If they both read close to the same for the various voltage, current, and resistance ranges, then they are both likely in reasonable calibration. Note that most applications don't require a high degree of measurement accuracy. The most might be needed for measuring the state of charge of a battery.

    If you want to check absolute calibration, then you could compare them to a known calibrated meter as nsaspook suggested.
     
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  5. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    calibrate against any good 4 1/2 digit DMM.
     
  6. nsaspook

    AAC Fanatic!

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  7. bug13

    Thread Starter Well-Known Member

    Feb 13, 2012
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    I just check my meters with a $3 2.048v precision Zener voltage reference, my 3 digit meter reads 3.05, my 4 digit one reads 2.045, not bad for a $20 meters

    but I definitely won't use them in main, as I has opened them up and they both use those 10c glass fuse. No good.

    Thanks guys!
     
  8. WBahn

    Moderator

    Mar 31, 2012
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    Couldn't even start to watch the video bcause of the dozens of cookies the site was trying to store on my computer.

    I bought a Micronta (i.e. Radio Shack) meter more than 30 years ago and last time I checked it against a calibrated bench meter (maybe five years ago) it was extremely close. I forget the specifics, but I don't think it varied by much more than 2% in the worst case and was usually under 1%. I got a second Micronta several years later (it is well over 20 years old) and although it has more (and useful) features, I don't like it nearly as well, but it was about the same in terms of accuracy when I checked it. Both of those meters have been pretty badly abused (like checking the line voltage in the place where I was living wile forgetting to switch from current to voltage mode).
     
  9. nsaspook

    AAC Fanatic!

    Aug 27, 2009
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    I must have sold a thousand Micronta pocket meters at Tandy RS when I worked for them as a teenager in the early 70's. The CB craze was in full swing so every trucker wanted something to check the voltage going to the radio. I'm sure I still have one in the attic at moms house.

    Yea, if you have the setting to ask for every cookie that site is nuts. I normally use Linux Firefox and only accept cookies from the origination website only.
     
  10. WBahn

    Moderator

    Mar 31, 2012
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    The one's I have were a step (or three) up from the true "pocket" meters. They were the same size, roughly, as the Fluke 77. I suspect (hope?) the quality was also a step up. Actually, I can't complain too much about the Radio Shack lines, such as Realistic, from that era (1980's, in my case). I had really good experiences with just about everything I bought from them. Not so, of course, a decade or two later.
     
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  11. nsaspook

    AAC Fanatic!

    Aug 27, 2009
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