Digital Multimeter Half-Digits Explained - Workbench Wednesdays
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- Опубліковано 17 бер 2020
- What does it mean for a DMM to have 3.5 digits? How much more accurate is a 5.5 digit multimeter versus a 4.75 digit meter? Many people assume that more digits mean more accuracy. However, these numbers express the precision of the meter, not its accuracy! In this video, learn about a DMM's accuracy, what does "half a digit" mean: bit.ly/2vR7qj5
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Very good presentation, well done and for the record, his blue work bench in his foreground is a Tek 7000 series scope!
Great treatment of this subject. A majority of the time I can get away with "knock around" multimeters but have one "good" meter that is only used when I need instrumentation quality measurements.
Calculation at 5:22 is wrong, because the range is 20 V not 3.3 V, but it will not affect the result.
Right is:
3.3 - ((0.015% * 3.3) + (0.004% * 20)) = 3.299
3.3 + ((0.015% * 3.3) + (0.004% * 20)) = 3.301
The inherent problem with internet learning, you think you're learning correct info but instead you're being taught wrong info; you take that, pass it along, and eventually we end up with a flat earth society.
That's still only a 4.5 digit result :)
Actually, the datasheet of your multimeter specifies 5/6 (not 5/8), which sounds about right.
5/6 --> 6 possible numbers. 5, the highest number that digit will display.
1/2--> 2 possible numbers. 1 the highest number.
So 1/2 is not really a fraction and shouldn't be called "a half".
Yes it is confusing. Number of counts is better.
gabriel tabermero , But what is that going to be vs. digits? Counts may be wasted accuracy if it is not displayed correctly.
Thanks, I always wondered what half a digit really was.
Gracis por el video
Pretty decent video. Cleared up a lot for me. Oh, by the way, you gonna do anything with that Tek 7000 series scope or just use it as an arm rest?
😉
Owner of a venerable 7704A and it's my pride and joy!
Uffff tks For this great vídeo, 🤝🎩💯😊
Доходчиво и кратко. Спасибо!
Nice
Hi, Great videos by the way. Its been a while i have not used an Oscilloscope. I am considering buying this scope,
OWON XDS3104E Digital Oscilloscope. Is 100 Mhz sufficient for most applications or should i consider 200 Mhz?
If you had to buy 5.5 or 6.5 benchtop DMM, which one would you buy? Thank you for your videos!!!
@jameshisself Any specific brand? You also have a meter like Owon bench multimeter lookalike, it starts with M...PRO you've demonstrated once I think. Any good? What do you like and dislike about it? Is it made by Owon? When I researched it sometimes ago, it stated that it is made by the brand M..PRO, but the Owon looks identical. I'm confused, but I'm looking for an accurate 5.5 or 6.5 (I can't afford the 7.5) digit Benchtop DMM. I like the large display and even touchscreen but they are also expensive. I do understand the extra digits and mainly the ACCURACY is the most important! I get it and I agree, but before I spend some $$ I like to get others opinion and do more homework. If you had a budget about $1000, which one would you buy? Thanks again for your videos and your time!
@jameshisself You are FAST! Thank you for your suggestions!
Mine has 3.14159 digits
John Bond , But actually, you needed 3.14159265 digits to read your value, right?
@@BruceNitroxpro ua-cam.com/video/gmfI6vwAqdw/v-deo.html
Nice video. Thanks for the simple explanations. Please, stop the annoying click sound though.
datasheet says 3 5/6. Sounds odd, 5/8 sounds better.
Doesn't these values also change over time?
Yes, there are services that will recalibrate your instruments for $$$. Calibration usually lasts a year or two depending on the device. Often it is cheaper for a company to toss a device and buy a new one. This is where a hobbyist can pickup quality instruments on the cheap. As long as you realize they might be out of spec, it usually isn't really too much of a problem.
@@DaveMcAnulty interesting, my mind boggles how they calibrate in the first place
@@lloydtshare A more expensive version of the same equipment. :) There is always a bigger fish.
@@DaveMcAnulty but how was the more expensive equipment calibrated, maybe some sort of average?
@@DaveMcAnulty I've worked it out i know how it's done 😉
reading the comments I come to realize James doesn't know everything, he did say "it can be confusing" 00:25 - 00:26 I learned more in the comments than in the video.
try auto 2v setting,,, stick in 1.5v battery....
3/4 digit isn't 0.75; instead it should be able to display 4 different possible value for its Most Significant Digit that is from 0, 1, 2, 3
(4 different number capability).
For 6000 count it should be 5/6 digit for MSB, ie. 0,1,2,3, 4,5 (6 different number capability).
2000 counts become 1/2 or 2 different values for its MSB ie. 0 or 1.
Now, let's see 5000 count vs 50000 count vs 500000;
It should be noted as 3 and 5/6 digit vs 4 & 5/6 digit and 5 & 5/6 digit.
You got the idea for whatever count and so on.
22000 count?
4 and 1/2 digit then.
Budi Suryadinata , Exactly!
As my explanation for this topic is like this ;
The integer number is clearly meaning the number of digits before the decimal point....
The fraction number is meaning the upper range limit for the counts and should not be treated as a fractional number but as relative number so 3.5 digits does not mean 3 digits and half but as 3 1/2 which sounds like 3 1-to-2 which means the upper limit of meter counts is in the range of 1-to-2 like 1999 ( the upper limit of counts is within the range of 1000 to 2000 ).... Another example is 4.75 which is more correctly to say 4 3/4 ( 4 digits and 3-to-4 , 3000-to-4000 counts ) =3999 ( denoted as 4000 counts meter type ) or could be also 3199 ( denoted as 3200 counts meter type ).... 3 5/6 ( 3 digits and 5-to-6 upper limit range of counts ) =5999 or 6000 counts..... Is it clear now people ??!! ...
Thank you. Much better explanation than the video. Video is not simple enough. İ was confused.
As a second note; the notation of this digit system seems unnecessarily complex. Just because something can be written short doesn’t mean it s easier and more user friendly. Human brain is not a compiler that needs a short and smart code. Brain works obviously differently.
@@sds123faf You are welcome ... But that complexity was not for normal people and unprofessional... These instruments are basically for B2B class products which has nothing to do with consumer products so every user in B2B should have a degree of smartness than normal grade, i.e. who is working on 5 or 6 digits resolutions must be a special smart guy...
uh... I hate to bring this up.. but your data sheet at 1:55 says 5/6th not 5/8th.. and your right.. this is confusing.. my multimeter works just fine.. go back and fix your 5/6th and 5/8th problems and come back.. In the meantime I will try and find one of these strange multimeters you have so we can be on the same page.. I am 68 and sometimes I am not hip to this new stuff yet.. and the old adage "if it works good.. fix it!"
شكرا جيم
انت جزائري
@@ifmohammed6495 لا انا من العراق
So 0.75 > 1, got it 🙂
Counts is not precision, counts is resolution, nothing more.
Your 5.5 digit calculations, showed 0.004% * 3.3, when it should be * 20. And it showed a 4.5 digit reading instead of a 5.5 digit. You could see the extra digit in the physical multimeter a few seconds of video previous.
You missed the point. It was showing the difference between accuracy and precision. Digits/Counts are precision, not accuracy.
What the hell man? You say count can help us understand more about meter specs, then stick up a title card that says "COUNT".. but in the segment you talk about decimal point, measurement range, and digits WITHOUT EVER MENTIONING COUNT!!
Does it clarify how the counts spec helps, when you don't say what the spec is on this meter, or explain what it means?
(Maybe if you'd said 'the count spec on this meter is 5999, which means the maximum it can display is...')
Then, just to be (more) confusing you say that the meter has to switch ranges to display any value over six.point THREE? What about 6.00? 6.01? 6.02? (etc).
Then you make the point that 6.300 is displayed as 6.29??
You really need to proofread your script better....
It's easy. The counts tell you the highest number the display can show.
A typical 2000 count meter can show from 0000 to 1999, which is the same as 3 1/2 digits.
The 6000 count meter goes from 0000 to 5999, that's a 3 5/6 digit display.
You see, the only difference is the moment when the decimal point moves over. If you want to make precise measurements in a range between 1999 and 5999, you better choose the 6000 count meter because you keep the better resolution.
A 50.000 count meter displays from 00000 to 49999, also called 4 4/5 digits.
Also, the accuracy is related to the counts. A meter with 6 digits has to me way more accurate than one with 4 digits, otherwise it woudn't make sense.
@@schorse1000 Thanks for that. It's the clearest explanation of the count spec I've ever seen.
I still think James should've explained what a count spec is, rather than just throwing a bunch of numbers up while pretending it helps explain what the digits spec meant.
Plus - despite my typo on the actual number - I stand by my contention that he was just confusing things further by saying the meter "must switch to it's 60 volt range to display anything above *6.2* volts", at the same time as the meter showed *6.3* volts. (The "point two" makes no sense whatsoever, since the meter would have to switch ranges to display anything over 5.999 volts). And to top it off, he then says "the tens place wastes one entire digit, so six point three zero zero volts gets displayed as zero six point two nine", as if that was going to clear up anyone's confusion. Especially as the meter clearly showed 06.30 when he first changed ranges...