Author Topic: Accuracy DMM  (Read 1197 times)

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Offline JanJansen

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Accuracy DMM
« on: December 14, 2016, 02:32:29 pm »
Hi, does DMMs with hi accuracy have these numbers for nothing ?,
i mean, do they jump around ?, or does it give a stable reading acros all digits ?
Is it worth buying ?

thank you
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Offline Fortran

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Re: Accuracy DMM
« Reply #1 on: December 14, 2016, 03:06:30 pm »
Check the manual for the DMM in question. It should say what kind of accuracy you can expect.

One of my HP's have a "High Resolution" mode, which sacrifices update rate and takes a lot of samples and averages them out which sometimes gives you an extra digit depending on your range.
They might mean something like that, but again, that would be mentioned in the manual.

If you're measuring a clean supply, you get a clean reading.
If your supply is full of ripple, it doesn't matter how good the multimeter is, you're still gonna get the last digit(s) jumping around.

 

Offline JanJansen

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Re: Accuracy DMM
« Reply #2 on: December 14, 2016, 03:30:53 pm »
I mean more for with resistors or diodes, do they give stable reading ?
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Online Kleinstein

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Re: Accuracy DMM
« Reply #3 on: December 14, 2016, 03:50:18 pm »
It is quite common that the last digit is moving a round a little. It also depends on the range and update rate used. Slower readings can be more stable and sometime even show an extra digit.
Quite often accuracy is not as good as the resolution  - so the last digit or sometimes even more are not guarantied to be accurate, but it can be still useful to see small changes and the difference can than still be meaningful.

With the resistor ranges it is well possible that the ranges for the high resistors (e.g. 2 M and more) are a little less stable. The reading on high resistors is just sensitive to external capacitive coupled disturbance and more noise by principle.

Similar the other ranges might not be all the same accuracy. Especially AC readings are usually less accurate. So check the manual to compare - not just looking at the number of digits / counts.
 

Offline Fortran

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Re: Accuracy DMM
« Reply #4 on: December 14, 2016, 04:22:31 pm »
To put it this way.
Which multimeter(s) are you looking at, and what do you intend to use it for?
If the "hi resolution" you mention is a marketing scheme, or an actual feature, we'll know pretty instantly. :)
 

Offline JanJansen

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Re: Accuracy DMM
« Reply #5 on: December 14, 2016, 04:37:46 pm »
I am looking to a : Hameg HMC8012

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