Author Topic: How much accuracy do YOU really need?  (Read 3775 times)

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Offline TimFox

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Re: How much accuracy do YOU really need?
« Reply #25 on: February 11, 2023, 05:37:03 am »
Another potential problem with any ADC system is stuck bits:  a diagnostic can tabulate the frequency of the individual bits to look for stickiness.
 

Offline madires

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Re: How much accuracy do YOU really need?
« Reply #26 on: February 11, 2023, 01:10:39 pm »
accuracy <-> precision <-> resolution

Umm... what do you mean by the "<->" symbol?

Arrows. All three are different things, but still connected.
 

Offline David Hess

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Re: How much accuracy do YOU really need?
« Reply #27 on: February 11, 2023, 02:25:12 pm »
Another potential problem with any ADC system is stuck bits:  a diagnostic can tabulate the frequency of the individual bits to look for stickiness.

Missing codes and lack of being monotonic may or may not indicate a problem depending on the design and resolution.
 

Offline Siwastaja

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Re: How much accuracy do YOU really need?
« Reply #28 on: February 11, 2023, 02:53:51 pm »
Test gear is 99% masturbation.

Whether the accuracy specs matter for real projects, completely depends on what kind of projects one works with. Generally most of the projects are fine with 2-3 digits of resolution and 1-5% of accuracy in pretty much everything, but if your specific project needs higher accuracy, then such generalization is not helpful for that project.

Incidentally, people who discuss and collect highly accurate test gear almost never build any actual projects that need this accuracy. At most, they build more test gear.
 
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Offline TimFox

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Re: How much accuracy do YOU really need?
« Reply #29 on: February 11, 2023, 03:02:37 pm »
Another potential problem with any ADC system is stuck bits:  a diagnostic can tabulate the frequency of the individual bits to look for stickiness.

Missing codes and lack of being monotonic may or may not indicate a problem depending on the design and resolution.

My experience where it was a problem were on large-scale digitized x-ray detector arrays.
 

Offline madires

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Re: How much accuracy do YOU really need?
« Reply #30 on: February 11, 2023, 04:23:09 pm »
Incidentally, people who discuss and collect highly accurate test gear almost never build any actual projects that need this accuracy. At most, they build more test gear.

Just in case, there's a group therapy thread: https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/  ;D
 
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Offline MathWizard

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Re: How much accuracy do YOU really need?
« Reply #31 on: February 12, 2023, 12:21:19 am »
Using my Siglent SDM3065X, 6.5d meter, I was measuring VBE of some BJT's w/ 10G input Z mode, and 100PLC, I still found I could only get down to milli-volt levels. Because the temperature drift I guess, it just seemed to keep going. I need to check that more, see if the starting values are always around the same into the uV, and see where it goes if left a long time.

But yeah it worked good enough to match the diode equations. I have a few other meters, I should see how they do. I never really compared them much. Just lately, I was checking my Keithley 197 5.5d meter, and it sure settles on a value nicer than the Siglent, when its not on  10-100PLC. IDK what downside the K197 has that way, but it makes the faster, Silent way, seem pointless, in that it just spews numbers in the lower digits. Sometimes that can be useful, but it's hard to look at. Thats why unless I want the delay of 1-100PLC, I mainly use 0.6PLC.
« Last Edit: February 12, 2023, 12:25:37 am by MathWizard »
 

Offline bdunham7

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Re: How much accuracy do YOU really need?
« Reply #32 on: February 12, 2023, 02:08:02 am »
Test gear is 99% masturbation.

Everyone needs a hobby.
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 


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