Author Topic: EEVBlog 121GW Discussion thread  (Read 767283 times)

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Offline kcbrown

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Re: EEVBlog 121GW Discussion thread
« Reply #50 on: January 16, 2018, 08:54:34 pm »
I think people are ignoring what is perhaps the most important question about this meter:  can it handle a 1.21GW burst of electricity?    ;D

Sadly, nobody has performed such a test, perhaps because it's difficult to put together.  Even Joe might not be able to do that.  Sounds like it might be a good opportunity for him to expand his pulse test equipment lineup.    :-DD

We're rooting for you, Joe!
 

Offline 1anX

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Re: EEVBlog 121GW Discussion thread
« Reply #51 on: January 16, 2018, 09:35:13 pm »
When Dave gets back he can address this the way he feels appropriate. Can the 121GW be speeded up?

Almost certainly.
It is being worked on as the first priority, but do not ask for an update, I do not have one.

Quote
what auto-range speed would the current HW allow?

That's a much harder question to answer. Look at the Keysight 1282A perhaps, that uses the exact same front end chipset.

Looks to me like Dave has answered the most asked question in all the numerous discussions on this meter on this forum! Maybe just maybe, we can move on for a moment to some other areas of discussion?

Personally I'm annoyed by this issue just like everyone else, but "for the love of god", (quoted ya Dave) can we give them a little time to bring out the new firmware fix!
 
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Offline joeqsmith

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Re: EEVBlog 121GW Discussion thread
« Reply #52 on: January 16, 2018, 11:03:07 pm »
I think people are ignoring what is perhaps the most important question about this meter:  can it handle a 1.21GW burst of electricity?    ;D

Sadly, nobody has performed such a test, perhaps because it's difficult to put together.  Even Joe might not be able to do that.  Sounds like it might be a good opportunity for him to expand his pulse test equipment lineup.    :-DD

We're rooting for you, Joe!
Maybe someone will send one to photonicinduction to put across his large cap.   :-DD

Thanks for showing this!               

And here’s the major WTF moment - infinity to zero ohms - the Gossen is 4.1 sec just like I measured before - but the prototype 121GW is 3.8 sec!! compared to 7.4 sec on the production model I measured in Robert Culver's video - who showed how slow it was compared to his U1253 - a DMM Dave had ridiculed for being slow long time ago.

I wouldn't be surprised if joe got a cleaner more consistent contact is his test and possibly Robert Culver (unknowingly) had a bad probe or lead.
 
Also much of the ‘commotion’ with this issue being people’s different perspective of a fast/slow DMM - and not really prepared for what to expect with the 121GW - which was why I started to measure the time as accurate as possible in the video clips.

The U1282A was 3.5 and about 3.0 sec in 9fps mode - still kinda slooowish but more acceptable and hopefully 121GW can beat that.
 

No problem.  Keep in mind both meters change states at the same time.  You can't tell when this happens in the video, only that the meters do eventually start to respond.   You can however tell which meter is faster by which settles first.  There is a fair amount of variance.  Again, I am not mechanically switching the signals for these tests.  As far as the response of the meter, consider the switching errors in the setup negligible.

For those of you that have an obsessive compulsive disorder, I setup another test.  This time using the a frequency counter and Arb to count 1ms events.  Events are sent to the counter at the same time the signals are sent to both the Gossen and prototype UEI meter.    After 10 seconds, I remove reset each meter to their over range state. 

I made four short to open cycles.  Sorry but the high frame rate of the camera limits recording to 4 seconds and the meters are just too slow to capture the entire event.   So I stretched the start and stop of each event to help provide a better estimate.   

For the true OCD people out there, this is not going to be enough.  So I set the camera to manual trigger at 1000fps.  I then captured the last few seconds where the meters settle.  I then repeat this a second time.  Just in these two cycles, we can see the UEI meter change by roughly 40ms and the Gossen by 80ms.   

Again, I can't stress enough that this is NOT the released camera meter.  :-DD  It was an early prototype that Dave provided.  The data shown may not be representative of the released product.

https://youtu.be/13nv-NsQXDs



« Last Edit: January 18, 2018, 12:44:59 am by joeqsmith »
 
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Offline ez24

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Re: EEVBlog 121GW Discussion thread
« Reply #53 on: January 17, 2018, 02:08:18 am »
I think people are ignoring what is perhaps the most important question about this meter:  can it handle a 1.21GW burst of electricity?    ;D
Since that is enough to power 1,000,000 homes it might require a shunt. 
YouTube and Website Electronic Resources ------>  https://www.eevblog.com/forum/other-blog-specific/a/msg1341166/#msg1341166
 

Offline VK5RC

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Re: EEVBlog 121GW Discussion thread
« Reply #54 on: January 17, 2018, 10:31:20 am »
I have done a rough-as-guts comparison of my handheld DMM collection in terms of resistance Auto-ranging time.
The winner ( - chicken dinner) is a 3458 (not fair I know) but then a Gossen. The 121GW is quite close to the Keysight U1282A - as Dave states above -the same chip.



Edit, Grammar
PS If I recall, Dave's criticism of the U1253 was mainly the timing of 'continuity' not the standard resistance range. The U1253B is slow in continuity but does give a reading of ohms - presumably for short finding.
« Last Edit: January 17, 2018, 10:38:35 am by VK5RC »
Whoah! Watch where that landed we might need it later.
 
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Offline ez24

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Re: EEVBlog 121GW Discussion thread
« Reply #55 on: January 17, 2018, 06:49:52 pm »
I have done a rough-as-guts comparison of my handheld DMM collection ....

If you turned on everything, you would need a 1.21 GW meter to measure the kW used.   :-DD
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Offline Terry01

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Re: EEVBlog 121GW Discussion thread
« Reply #56 on: January 17, 2018, 07:45:02 pm »
Holy Smokes!

Is all that equipment for home/hobby use?
Sparks and Smoke means i'm nearly there!
 

Offline VK5RC

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Re: EEVBlog 121GW Discussion thread
« Reply #57 on: January 18, 2018, 01:15:13 am »
Don't tell my wife! HiHi
It is about 20yrs of selective purchases.
No,  she knows, I don't look at her shoes / handbags / lululemon running gear!

I wanted to post the big variations in hand dmm autoranging time.
« Last Edit: January 18, 2018, 01:33:22 am by VK5RC »
Whoah! Watch where that landed we might need it later.
 

Offline dcac

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Re: EEVBlog 121GW Discussion thread
« Reply #58 on: January 18, 2018, 03:34:46 am »
@VK5RC - Thanks for testing your 121GW again and provide even more comparisons with your other DMMs - indeed an impressive collection you have there.

I also thought I mention this as it might help tracking down a possible bug. Even though the probes seems to be closed firmly - the bargraph flicker a couple of times just as if there was intermittent connection. I thought I saw the same flicker in the first video and that’s why I made that comment earlier about the probes possibly being bad. But from what I can tell now - the flicker seems to happen in more or less the same place in the auto-ranging sequence - most noticeably when going from Mohms to Kohms.

The bargraph on Joe’s prototype 121GW did not seem to flicker at all.

 

Offline dcac

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Re: EEVBlog 121GW Discussion thread
« Reply #59 on: January 18, 2018, 04:12:35 am »
The bargraph on Joe’s prototype 121GW did not seem to flicker at all.

No but in that last attempt you can clearly see the fade in vs the half and half, or should I say half + 1 segment.   :-DD   

I could run a side by side of the meters that have survived all my abuse along with the counter to time it.  Seems like an easier way to measure them anyway.  My old analog meter settles pretty fast but does not have auto ranging.  :-DD

Just to clarify - in my previous post I meant the two times Robert Culver tested his 121GW I saw the bargraph flicker in more or less the same place - as if the connection between his probes was intermittent. Compared to your prototype where the bargraph did not seem to flicker at all. Possibly this could be the indication of a bug the auto-ranging routine in Robet’s 121GW that causes bargraph flicker and overall slow auto-ranging speed.

 

Online beanflying

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Re: EEVBlog 121GW Discussion thread
« Reply #60 on: January 18, 2018, 04:15:29 am »
Seems either the meter and or the reference has drifted 2 LSD.  Decided not to try and figure out which as Yep that is 42+ degrees C on the bench  :phew:
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Online beanflying

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Re: EEVBlog 121GW Discussion thread
« Reply #61 on: January 18, 2018, 04:19:37 am »

Just to clarify - in my previous post I meant the two times Robert Culver tested his 121GW I saw the bargraph flicker in more or less the same place - as if the connection between his probes was intermittent. Compared to your prototype where the bargraph did not seem to flicker at all. Possibly this could be the indication of a bug the auto-ranging routine in Robet’s 121GW that causes bargraph flicker and overall slow auto-ranging speed.

Just to clarify you are relying on the videos of others for the content of your last 25 posts to search for any perceived (by you) flaws in a product you haven't used in the flesh?  :palm:
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Offline EEVblog

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Re: EEVBlog 121GW Discussion thread
« Reply #62 on: January 18, 2018, 11:39:59 am »
Seems either the meter and or the reference has drifted 2 LSD.  Decided not to try and figure out which as Yep that is 42+ degrees C on the bench  :phew:

Reminds me of the old garage EEVblog lab. In old videos you can see the sweat running down my forehead.
 

Offline iainwhite

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Re: EEVBlog 121GW Discussion thread
« Reply #63 on: January 18, 2018, 01:55:52 pm »
Has anyone in the USA received theirs?

Joe, I received mine on Jan 8th.   I think there were at least a couple of other US guys that have too.
 

Offline dcac

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Re: EEVBlog 121GW Discussion thread
« Reply #64 on: January 18, 2018, 02:10:44 pm »
Just to clarify you are relying on the videos of others for the content of your last 25 posts to search for any perceived (by you) flaws in a product you haven't used in the flesh?  :palm:

Interesting comment on a Video blog related forum. For me videos are very useful to evaluate a product’s performance or apparent flaws, sorry if you can’t do that, please feel free to ignore my posts.

 
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Offline idpromnut

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Re: EEVBlog 121GW Discussion thread
« Reply #65 on: January 18, 2018, 06:56:22 pm »
Probably off topic (a bit), but I am ashamed to say that the significance of this evaded me (as I was busy exploring the meter functionality, and not the serial number on the back):
 
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Offline logictom

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Re: EEVBlog 121GW Discussion thread
« Reply #66 on: January 18, 2018, 09:23:20 pm »
Just to clarify you are relying on the videos of others for the content of your last 25 posts to search for any perceived (by you) flaws in a product you haven't used in the flesh?  :palm:

Interesting comment on a Video blog related forum. For me videos are very useful to evaluate a product’s performance or apparent flaws, sorry if you can’t do that, please feel free to ignore my posts.

I don't see the issue with this. I think some people are getting a little bit too fanboy, don't get me wrong, I bought one aswell with the explicit need, it's always good to have more meters and to support Dave. How is critiquing this from video any different to us all saying how dumb apple was to remove the 3.5mm jack on the latest iPhone without most of us owning one.

Banging on the same issue in multiple posts without adding anything to the discussion is another thing, but evaluating a product via video and without owning it - how else would we decide on what to buy from all these online only retailers.
 

Offline maukka

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Re: EEVBlog 121GW Discussion thread
« Reply #67 on: January 19, 2018, 04:06:21 pm »
Did a 10 hour logging of temperature simultaneously with a Uni-T UT181A at 60 second sampling interval. Also another one for voltage for a couple of hours at 1 second interval while discharging a battery. Was very happy to find that they're perfectly in sync. While a Mooshimeter for example drifts compared to them.
« Last Edit: January 19, 2018, 04:08:13 pm by maukka »
 
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Offline 1anX

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Re: EEVBlog 121GW Discussion thread
« Reply #68 on: January 20, 2018, 03:32:10 am »
I wrote the following on another thread in this forum after Dave made clear that the wobbly switch issue had been confirmed. I think its more appropriate that its posted on the "Discussion" thread!

It doesn't matter to me about what the details were of the past prototypes!

I'm concerned about the current production models and what I'm going to receive come March 2018. Its not so much about the existence of the problems encountered with the production model, but about how it will be fixed.

There are two items of concern and they are the current meters now delivered may have a hardware issue and how will this be addressed?

The Kickstarter way of buying a new meter is certainly a new experience for me, as it is without certainty or guarantee. I would not have engaged in the campaign if not for finding Dave and his blog to be 100% genuine. I'm certain the existing owners will be looked after and the next batch of meters will be fixed before being shipped.

Dave we need you to communicate a reassurance that hardware and firmware will be fixed. We are all reasonable people and understand this may take some time. Give us one of your EEVBlogs on how the Kickstarter project meters have some issues and whats needed to fix them. Give us some of your trademark sarcasm and humour and include us, (the backers) in how you progress from here. 
« Last Edit: January 20, 2018, 03:34:20 am by 1anX »
 

Offline tpw_rules

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Re: EEVBlog 121GW Discussion thread
« Reply #69 on: January 20, 2018, 07:40:51 pm »
Is the fully open schematic available yet? I'd like to get a peek to answer some questions.

Relatedly, I've cooked up a firmware with a tweak to autoranging that should improve the speed significantly. Trouble is, I've not yet received my meter. Anybody want to PM me and give it a go?
 

Offline bicycleguy

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Re: EEVBlog 121GW Discussion thread
« Reply #70 on: January 21, 2018, 02:07:39 am »
Asked that on the kickstarter page and received this from Dave on January 15th:

They are being neatened up by UEI soon to be released, it will be posted in an update.
 
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Offline mikeselectricstuff

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Re: EEVBlog 121GW Discussion thread
« Reply #71 on: January 21, 2018, 09:34:26 am »
Asked that on the kickstarter page and received this from Dave on January 15th:

They are being neatened up by UEI soon to be released, it will be posted in an update.
Any word on publishing the format of the cal data and firmware files - these would be prerequisites for alternative firmware - probably possible to reverse-engineer, though it would be a bit of a pain.
BTW is a full end-user recalibration possible ( this would make reversing the cal data easier if nothing else)?
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Offline dcac

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Re: EEVBlog 121GW Discussion thread
« Reply #72 on: January 21, 2018, 12:10:31 pm »
BTW is a full end-user recalibration possible ( this would make reversing the cal data easier if nothing else)?

Seems to be, have a look at page 58 in the manual:

http://www.eevblog.com/files/EEVblog-121GW-Manual.pdf
 

Offline mikeselectricstuff

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Re: EEVBlog 121GW Discussion thread
« Reply #73 on: January 21, 2018, 12:18:38 pm »
BTW is a full end-user recalibration possible ( this would make reversing the cal data easier if nothing else)?

Seems to be, have a look at page 58 in the manual:

http://www.eevblog.com/files/EEVblog-121GW-Manual.pdf
Quote
4. Hold your breath, cross your fingers, and don't make any sudden
movements that could frighten the meter. Beard stroking is allowed.
What, no tongue angle specification ?

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Offline tpw_rules

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Re: EEVBlog 121GW Discussion thread
« Reply #74 on: January 21, 2018, 04:08:07 pm »
Any word on publishing the format of the cal data and firmware files - these would be prerequisites for alternative firmware - probably possible to reverse-engineer, though it would be a bit of a pain.
BTW is a full end-user recalibration possible ( this would make reversing the cal data easier if nothing else)?

So, IDA and I have been having a bit of fun over the past week and I now have a perhaps 80% complete IDA database of the 1.02 firmware. I'm hesitant to release it because a) it's not done and b) I don't know what UEI would think. I also can't test a lot of theories because my own meter is not here yet.

Anyway, regarding the format of the firmware file. The CPU is an STM32L152 family Cortex-M3 ARMv7-M processor. I don't know what exact chip it is. If anyone could send me a photo of the exact chip in the meter, I would be grateful. The EEVBlog.bin file is burned into ROM starting at 0x08006000. It has a standard Cortex-M3 vector table at the start, where the first 32 bits are the initial SP and the second are the reset vector (+ 1 because the processor always operates in Thumb-2 mode). This is enough to get it disassembling correctly in IDA, or to start your own firmware once the exact chip is known.

Regarding calibration data, it actually seems possible to load and save the calibration area of the EEPROM to the SD card. As before, I can't test it cause I don't have a meter. There is a non-zero chance you could lose all your cal data or start a fire.  If you want to try, here is the procedure:
  • Boot holding the MEM key, or maybe boot the meter with no keys and quickly press MEM. (I'm not entirely sure) Screen will show SdCAL if you did it.
  • Press PEAK to load calibration data from SD card (screen shows SdSEt) or REL to save data to card (screen shows SdSAv).
  • Press MODE to do it. If successful, screen shows SAvEd. Else, screen shows -Err-.
  • Turn off the meter. The data is now in cal.bin on the SD card.
The cal.bin file is a copy of the first 1200 bytes of EEPROM. The first 48 bytes are used for settings, the rest of the 1200 bytes is calibration factors, and the rest of the EEPROM is involved with logging.

A lot of the ranges share factors and there are some I'm not too sure about. The official manual is pretty light on details, and it seems there are other things such as a bonus 50Mohm range calibration and some frequency calibration factors for the AC ranges which are not mentioned. (And what's with 10% for the AC ranges? Is that 10% of full scale as opposed to a dead short?) Fortunately, for most modes and ranges, it is indeed a simple 0 offset and a full-scale gain and I know which ones use which factors. Sadly, I'm not a metrologist, and these areas are heavy on algorithms I don't understand, so I'm having trouble. But I intend on communicating whatever I learn when I do learn it.

And Dave, could you give me an OK/over my dead body on releasing the work?
 
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