EEVblog Electronics Community Forum
EEVblog => EEVblog Specific => Topic started by: GlennSprigg on October 19, 2017, 02:57:18 pm
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Hi Dave. I hope all is going well with your progress here !!
I've checked out all the OLDER videos, including those from 'Joe Smith'.
since your 'BM235' onwards through the '121GW' prototype......
Not being an expert like you Dave, I have always been curious about a few points.
(Just trying to understand Dave)..... If a 'Meter' has 3 decimal points in a particular
range, (like reading 4.367v), obviously this depends on the specified % accuracy.
However, for a '9999-count' meter, showing say..... '4.3674v', how does this have
any real meaning, UNLESS the devices 'accuracy' is say '.005%' ? on that scale ??
The 'Numbers' are there.... but the final digits mean little anyway ?????
And in regards to the above, I would at least 'like' a Meter to have a 'Zero' button,
to compensate for Lead Resistance etc. for continuity/ohms/volts......
Keep up the great work Dave, & Hi to your family for supporting you !!
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I could be wrong here as I'm just a novice.
As an example, a temperature meter may be accurate up to 1 degree, but show 0.1 degrees resolution. Even though this decimal value won't be accurate, and you can't count on "1.4" being actually "1.4", they should still be able to indicate some relative rise/drop of temperature that is less than 1 degree. With two calibrated meters measuring two spots, you could know which is warmer/colder, even at less than 1 degree.
So, a multimeter accurate to 0.1v might be able to show some relative rise/drop of voltage from 0.10 to 0.19 even though you can't count on the number being exact/truthful.
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The number of digits defines the precision, which is not dependent on the meter accuracy, even though both are usually confused.
The attached image shows the difference way better than I could explain.
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Thank you to both of you for your responses !!!
I understand what you are both saying, but you may be missing my point.
I 'Know' there are always 'errors', and within the 'specs' that's acceptable.
I'm questioning the 'NEED' for say '4-decimal' assumed precision, when
due to the 'acceptable' specs % error, that last digit is virtually ignored ???
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One use of more precision than accuracy (or "too many digits") is for relative measurements, e.g. watching a battery discharge. You can compare the displayed values over a short time period but you can not relate them to another multimeter or the same multimeter the next day.
Btw, a 9999 count meter can not display "4.3674". You need an 50000 count meter for that.
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To 'Glarsson'
I understand what you are saying..... especially about watching a 'Change', as opposed to an actual value.
Regarding your observation about how . . . 9999 count meter can not display "4.3674"...... Oops !!!
You are right. My 'question' was 'relative', and not precise with my examples !!!
Granted ALL that, I would STILL like a Meter that has a 'ZERO' button, for 'Resistance' measurements etc.
PURELY OUT OF INTEREST !!!! :-).... Back in the 1970's when I was an Apprentice, I worked for the Major
power company in South Australia. (Called E.T.S.A. then). This was BEFORE anything 'digital' ever existed.
We had an ANALOG meter, that was the STANDARD for the whole STATE !!! It was in it's OWN room, and
sat on a concrete 'Plinth', that went down to it's OWN foundation through the floor, so that NO building vibrations
ever affected it's readings, or would ever cause any 'wear' on it's precision 'Jeweled' bearings.......
NOT to mention being temperature & humidity controlled !!!! It was the BASIS of all State-Wide calibrations.
I WONDER where it is now ????.... Now we use atomic clocks & satellites... but there are STILL basic 'references'.
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P.S. I would still love to hear from Dave, about his '121GW' Multimeter......
I'm really interested in hearing about how it is going !!! xx
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PURELY OUT OF INTEREST !!!! :-).... Back in the 1970's when I was an Apprentice, I worked for the Major
power company in South Australia. (Called E.T.S.A. then). This was BEFORE anything 'digital' ever existed.
We had an ANALOG meter, that was the STANDARD for the whole STATE !!! It was in it's OWN room, and
sat on a concrete 'Plinth', that went down to it's OWN foundation through the floor, so that NO building vibrations
ever affected it's readings, or would ever cause any 'wear' on it's precision 'Jeweled' bearings.......
NOT to mention being temperature & humidity controlled !!!! It was the BASIS of all State-Wide calibrations.
I WONDER where it is now ????.... Now we use atomic clocks & satellites... but there are STILL basic 'references'.
Nice! Would like to have seen that. I imagine the meter itself would have been very large.
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To 'joeqsmith'. Is that "Joe Smith" from 'YouTube', re: multimeter testing etc etc ?? (Been chatting lately).
YES, it was quite a large meter, which I 'THINK' was made by the original "AVO" meter company, but I may be wrong.
This was at least 45 years ago now! It was about 400 x 400 x 300 mm's, and had a relatively 'low' "Ohms/Volt" as
the coil construction itself was quite large. (None of this uA stuff!!!). I'm 'digressing' here, but THEN, most circuits
required a minimum load, (old technology), to produce accurate voltage measurement results, where as TODAY, the
OPPOSITE occurs, and the meter itself would be grossly affecting the results ! (I think you understand what I mean).
If it is YOU Joe, then as per prev conversations, your expertise is in low power & some RF applications. My INITIAL
training was with very high power/current distribution networks, and I ONLY mention this so as to explain the following....
In Australia, we use different voltages than the U.S.A. for power transmission. We often start at 275-kv, and then reduce
to many others, before locally at a suburban level it is usually 11kv Delta. After that, it is transformed to 415v 3-phase,
and when a "Delta to Star" transformer is used, the 'Star-point' is 240v to each 'Phase', (unlike your 110v/120v).
Now... when a TOTALLY UNLOADED open circuit 11kv transformer is measured, we may find thousands of volts on the
Neutral, (the star point), and a mis-match of thousands of volts on the other HV legs.... all due to NON Loading !!!
These days, in a simplified comparison, the 'outputs' from a Switch-Mode Power-Supply also need a specific/minimal
LOAD, in order to work!!... Damn it.... All I'm trying to say is that SOMETIMES a 'real' load is important !! :-) :-)
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To 'joeqsmith'. Is that "Joe Smith" from 'YouTube', re: multimeter testing etc etc ?? (Been chatting lately).
I think the link at the bottom of his post confirms that ;D
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Granted ALL that, I would STILL like a Meter that has a 'ZERO' button, for 'Resistance' measurements etc.
You'll be glad to hear then that it does have that feature (as do nearly all digital multimeters above the "dirt cheap" category), although it's usually called REL, for relative measurement.
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Granted ALL that, I would STILL like a Meter that has a 'ZERO' button, for 'Resistance' measurements etc.
You'll be glad to hear then that it does have that feature (as do nearly all digital multimeters above the "dirt cheap" category), although it's usually called REL, for relative measurement.
Aneng AN860B+ has it too for similar or slightly more than AN8008. It is only 6000 count though.
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Aneng AN860B+ has it too for similar or slightly more than AN8008. It is only 6000 count though.
Thumbs up for AN860B+, it's my favorite meter at the moment. :-+
There's a new meter on the block which looks a lot like an 8000 count, TrueRMS AN860B+ in an AN8008-style case (not the bouncy rubber case of the AN860B+). Feature set looks identical (although it's all mixed up on the dial so don't blame me if I missed something).
https://www.chinabrands.com/item/dropship-bside-zt301-portable-handheld-digital-multimeter-228435401-k.html?wid=1 (https://www.chinabrands.com/item/dropship-bside-zt301-portable-handheld-digital-multimeter-228435401-k.html?wid=1)
The CAT rating of these meter is a lie, obviously, but they measure very well and for low voltage work they're amazing value for money. One could fill in until Dave finally releases his meter.
PS: If you insist on 9999 counts there's also the ZT302 but the overall feature set isn't as good:
https://www.chinabrands.com/item/dropship-bside-zt302-portable-handheld-digital-multimeter-2284314-p.html (https://www.chinabrands.com/item/dropship-bside-zt302-portable-handheld-digital-multimeter-2284314-p.html)
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Thank you to everyone else who replied and explained......
I understand all you have said, and I thank you all !
Does 'Dave' have an input here, as I was basing my recommendations on his answers/progress....
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I saw where is posted one of the older videos for it on his second channel. It popped up as a recommendation. It appears to be the first meter with the molded rubber boot. Not sure why it would be released now as it hardly seem relevant anymore.
I was hoping to see it in full production early this year. Maybe the goal is to stir up some interest. I had a fair number of hits on the videos I made and have to believe there is plenty of interest already.
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Was reading some of the new comments about this new old video. It seems people may not be aware that all but one of the seventeen videos are now available in the 121GW Playlist on EEVBLOG2.
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Was reading some of the new comments about this new old video. It seems people may not be aware that all but one of the seventeen videos are now available in the 121GW Playlist on EEVBLOG2.
Yeah Joe, there seems to be a lot of confusion surrounding the 121GW for people who don't closely follow the various public threads and videos. I think it would be best if Dave made an official video soon to outline the launch timeline, including availability for Patreon subscribers / supporters and for the general public.
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I suspect many would not have access to the supporter's area which did not help. Seems they have tossed out a few crumbs from time to time but then Murphy steps in. There is always next year. With Dave's brand on the line, I doubt they would release it until they work out all the problems.
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Yes, I hear what you are saying 'nidlaX', (and others). I guess being a 'newbie' here I'm a bit confused :-)
Prob a tad off-topic here, but I had 'gathered' from quite a few Video Posts from Dave that he DOESN"T
like to read-all/answer from the Video comments themselves, and prefers people to direct Q&A via this Blog...
I was becoming an avid supporter of his posts, and had commented many times.... but am left with the feeling
that 'he' does not want to know me ?? If that's the case... Fine :-) Just tell me... (I'm a big boy now :-) ).
Failing that, (and he is just too busy these days), then us mere supporters & spreaders of his prominence,
could at least hear two to four words now and then, when the Multitude of video 'commenters' are ignored.
I'm a musician, (part-time, purely hobby), involved with the 'Folk' music scene. Our emphasis was ALWAYS
on sharing knowledge, & helping others. Never any 'Class' distinction.... some are 'Garbo's... some are lowly
tradesmen, (women), and some are doctors & psychologists. On the day, WE just get together, and MAKE
music. The GREAT leveler between us is this famous quote that I live by......
"May those who soar in the sky... WALK back down the Mountain, & teach those with 'Leadened' feet, to fly !!!!!
Do you understand what I mean ? :-)
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Hi Dave. I hope all is going well with your progress here !!
I've checked out all the OLDER videos, including those from 'Joe Smith'.
since your 'BM235' onwards through the '121GW' prototype......
Not being an expert like you Dave, I have always been curious about a few points.
(Just trying to understand Dave)..... If a 'Meter' has 3 decimal points in a particular
range, (like reading 4.367v), obviously this depends on the specified % accuracy.
However, for a '9999-count' meter, showing say..... '4.3674v', how does this have
any real meaning, UNLESS the devices 'accuracy' is say '.005%' ? on that scale ??
The 'Numbers' are there.... but the final digits mean little anyway ?????
You are talking about the usefulness of resolution on a meter.
There are many uses for high resolution which allows you to see small changes. You often don't need need accuracy in those measurements, just being able to see the changes is very useful.
For example:
https://www.youtube.com/watch?v=fJSNAyMmNGk (https://www.youtube.com/watch?v=fJSNAyMmNGk)
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Yes, I hear what you are saying 'nidlaX', (and others). I guess being a 'newbie' here I'm a bit confused :-)
Prob a tad off-topic here, but I had 'gathered' from quite a few Video Posts from Dave that he DOESN"T
like to read-all/answer from the Video comments themselves, and prefers people to direct Q&A via this Blog...
I was becoming an avid supporter of his posts, and had commented many times.... but am left with the feeling
that 'he' does not want to know me ?? If that's the case... Fine :-) Just tell me... (I'm a big boy now :-) ).
Failing that, (and he is just too busy these days), then us mere supporters & spreaders of his prominence,
could at least hear two to four words now and then, when the Multitude of video 'commenters' are ignored.
I get 80,000+ video views every day, 365 days a year, do you realise how many comments those video views get every day?
I can't possibly read or answer them all, but i do my best. I like to think I spend more time answering youtube video comments than most other creators of my channel size.
Also, I mostly comment on my latest videos. Answering comments on all my 1200+ previous videos isn't always practical.
As for the forum, I am the #1 poster on this forum, but there are 800+ new posts every day so I can't possible read them all, or even a large fraction of them.
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Yeah Joe, there seems to be a lot of confusion surrounding the 121GW for people who don't closely follow the various public threads and videos. I think it would be best if Dave made an official video soon to outline the launch timeline, including availability for Patreon subscribers / supporters and for the general public.
When I have something to say I'll say it.
I'm working on the Kickstarter right now and have 50 units about to be shipped to me.
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Thank you Dave for your replies.... (been in damn hospital, again!!...)...
I understand now, about the 'accuracy' thing with the 'digits', being that it more about 'Changes'. :-)
And I know your level of correspondence/comments is huge, so please forgive me :-)
I just didn't know if you preferred to read/comment on THIS forum, (when appropriate!) instead of the Videos.
It seems so many other Video-Bloggers I like are also bi-directionally supporters of you too !! and that's good.
May you, Nicole & Sagan have a great and rewarding future !!
P.S....
Has the name 'Sagan' have any ties to the late/great 'Carl Sagan' astronomer/physicist ?? (I followed him for years)
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P.S....
Has the name 'Sagan' have any ties to the late/great 'Carl Sagan' astronomer/physicist ?? (I followed him for years)
Dave has answered the question about his boys' names a while back:
Sagan... is he named after Carl Sagan?
Yes.
Huxley... is he named after Aldous Huxley?
No, his grandfather.
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Huxley... is he named after Aldous Huxley?
No, his grandfather.
I mean Aldous Huxley's grandfather BTW.
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The number of digits defines the precision, which is not dependent on the meter accuracy, even though both are usually confused.
The attached image shows the difference way better than I could explain.
This picture makes the concepts clear, but I would replace the word "precision" here with "stability". A stable voltage reference (whose value changes very little) is very valuable, even if it doesn't output the desired voltage level of say, 10.0000V, but instead outputs 6.28938V.
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It just occurred to me that a nice addition that might be possible in firmware in the V setting is a mode for dBV for AC volts.
I have other meters which give me this reading directly as a mode when measuring ACV. Just thought I'd put it out there.
- Geoff
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It just occurred to me that a nice addition that might be possible in firmware in the V setting is a mode for dBV for AC volts.
LOL, I forgot it actually has this already. Need to add that to the manual.
(https://i.imgur.com/UxBJ0UK.jpg)
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What is the reference impedance you use to calculate dBm ?
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It just occurred to me that a nice addition that might be possible in firmware in the V setting is a mode for dBV for AC volts.
LOL, I forgot it actually has this already. Need to add that to the manual.
Nice one Dave. Thanks!
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What is the reference impedance you use to calculate dBm ?
I presume standard 600ohm, but I haven't actually tried this as I forgot all about the feature :-[
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This may be source of great confusion for people especially RF people, as many assume 50 Ohm reference impedance. As DrGeoff said better use dBV.
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This may be source of great confusion for people especially RF people, as many assume 50 Ohm reference impedance. As DrGeoff said better use dBV.
The usual reference impedance on multimeters is for 600 \$\Omega\$ lines.
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Using dBV will eliminate all guesses. This is why I asked my question.
Edit: also, it is not terribly useful to have it tied to 600 Ohm. There is a multitude of measurements done with a multimeter with different circuit impedances, you do not want to recalculate every time, and may not need it in terms of power . In terms of voltage will be more useful, and that is dBV.
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Edit: also, it is not terribly useful to have it tied to 600 Ohm. There is a multitude of measurements done with a multimeter with different circuit impedances, you do not want to recalculate every time, and may not need it in terms of power . In terms of voltage will be more useful, and that is dBV.
600 ohms is the customary impedance for audio frequency measurements of dBm. Given the meter is likely out of spec for RF anyway, 50 ohms wouldn't make much sense. Maybe dBv would be preferable, but for AF, dBm is the tradition - maybe the assumed impedance should be configurable?
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The ancient Fluke 8050a has dB measurement and the REF. impedance is configurable, so having that ability on the 121GW would be very useful. Maybe displaying the currently set REF. IMP. briefly when the function is selected.
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Sorry for the bump- any further thoughts on this? dBv would be a nice change to this meter. My ancient Fluke 8050a and 8060a can do it, as can my 187.
Not complaining, just asking. The meter is great!
JT