Author Topic: EEVBlog 121GW Discussion thread  (Read 97019 times)

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Online dr.diesel

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Re: EEVBlog 121GW Discussion thread
« Reply #125 on: January 24, 2018, 10:02:39 am »
I'd like the option of recal to even further reduce the auto ranging time.   :-+

There are production meters in the field now, so we can't release firmware that would break the calibration, that would be very foolish.

One would of-course put this FW behind a warning of such.  If the improvement is negligible then who cares, but if significant it would be a shame to censor it for those of us capable of a full cal, which could be quite a few as we now pass cal standards around.

All depends on how much improvement is hiding behind the recal FW, which might be ~2sec as Mike suggested, making it very worthwhile.

Offline mikeselectricstuff

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Re: EEVBlog 121GW Discussion thread
« Reply #126 on: January 24, 2018, 10:23:53 am »
Any news on the US meters?

Yes, sorry but the US meters will be delayed, they want to make some small tolerance changes to the range switch. We'd rather have them delayed a bit than to have any more potential range switch issues.
Does the US batch include the EU ones that didn't pre-pay VAT? - ISTR you said some other countries were being fulfilled via US.
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Offline dcac

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Re: EEVBlog 121GW Discussion thread
« Reply #127 on: January 24, 2018, 10:26:49 am »
I wonder what clock rate the HY3131 in 121GW is running? - typical is 4.9152MHz but max is 8.0MHz according to the datasheet. If higher clock rate would mean faster auto-ranging (my guess is that it would) but then also less battery life - I would really go for faster auto-range as long as the 121GW has a auto-power off function.

It's 4.9152MHz
And I don't think that's how it work, it doubt it would magically make the autoranging faster. The micro controls the autoranging, not the HY3131.

Yeah you’re probably right, I notice now from the datasheet that range selection seems to be fully under software control by the MCU. So possibly only the actual ADC conversion would speed up with higher clock rate.

Great to see UEi responded so quickly and if  FW ver 1.04 achieved auto-ranging in 4.5 sec it’s a significant improvement over the 7.4 sec we saw before. More useful now for sure but still annoyingly slow. The prototype 121GW was 3.8 sec and U1282A about 3.0 sec in its fastmode, so there’s still room for improvement with a tweaked/hacked FW which I'm sure the programming wizards here at EEVblog eventually will provide.


 

Offline EEVblog

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Re: EEVBlog 121GW Discussion thread
« Reply #128 on: January 24, 2018, 11:02:05 am »
Does the US batch include the EU ones that didn't pre-pay VAT? - ISTR you said some other countries were being fulfilled via US.

No, we shipped those from here.
 

Offline benst

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Re: EEVBlog 121GW Discussion thread
« Reply #129 on: January 24, 2018, 11:03:12 am »
I see an app in the iOS App store called "EEVBlog 121GW" by Cheon Myoung-kun. That doesn't sound legit, does it?

And it looks bloody awfull.  :wtf:

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Offline EEVblog

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Re: EEVBlog 121GW Discussion thread
« Reply #130 on: January 24, 2018, 11:04:12 am »
I'd like the option of recal to even further reduce the auto ranging time.   :-+

There are production meters in the field now, so we can't release firmware that would break the calibration, that would be very foolish.
One would of-course put this FW behind a warning of such.  If the improvement is negligible then who cares, but if significant it would be a shame to censor it for those of us capable of a full cal, which could be quite a few as we now pass cal standards around.

Almost all users do not have the ability to calibrate the meter themselves, and you would be effectively forcing those users to do that if they wanted to upgrade their firmware in the future. That would be very poor form.
 

Offline EEVblog

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Re: EEVBlog 121GW Discussion thread
« Reply #131 on: January 24, 2018, 11:05:13 am »
I see an app in the iOS App store called "EEVBlog 121GW" by Cheon Myoung-kun. That doesn't sound legit, does it?
And it looks bloody awfull.  :wtf:

It is bloody awful which is why we wrote our own. But yes it is "legit". UEi got that person to write it.
 

Online dr.diesel

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Re: EEVBlog 121GW Discussion thread
« Reply #132 on: January 24, 2018, 11:08:35 am »
Almost all users do not have the ability to calibrate the meter themselves, and you would be effectively forcing those users to do that if they wanted to upgrade their firmware in the future. That would be very poor form.

I'm apparently communicating poorly, no worries.

Offline benst

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Re: EEVBlog 121GW Discussion thread
« Reply #133 on: January 24, 2018, 11:12:59 am »
I see an app in the iOS App store called "EEVBlog 121GW" by Cheon Myoung-kun. That doesn't sound legit, does it?
And it looks bloody awfull.  :wtf:

It is bloody awful which is why we wrote our own. But yes it is "legit". UEi got that person to write it.

Ok, good to know, thanks! Any idea when your app will be ready for iOS?

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Offline Kohanbash

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Re: EEVBlog 121GW Discussion thread
« Reply #134 on: January 24, 2018, 11:18:11 am »
Any news on the US meters?

Yes, sorry but the US meters will be delayed, they want to make some small tolerance changes to the range switch. We'd rather have them delayed a bit than to have any more potential range switch issues.

Just to verify the Great Scott meters for the USA are getting the updated switch. Were they already manufactured (I thought they were sitting in a dock somewhere)?

(I am not rushing this, I am just curious)
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Offline Scottjd

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Re: EEVBlog 121GW Discussion thread
« Reply #135 on: January 24, 2018, 11:21:30 am »
Any news on the US meters?

Yes, sorry but the US meters will be delayed, they want to make some small tolerance changes to the range switch. We'd rather have them delayed a bit than to have any more potential range switch issues.

Ok, so your saying the meters are now in the US, and UEI is taking them to fix the range switches. Will UEI be shipping them, or will they get shipped again to the reshipper in the US and then make it to the customers. Or did you can the reshipper and UEI will be shipping the US meter now?

I have an idea, it’s not uncommon to have 2 different firmwares for different hardware releases.
As a “Thank you for being patient” can the US customers request maybe UEI can update the auto range speed on the US meters and mark them hardware version 1.1. Since it will be at the manufacturer I’m sure they can calibrate for the faster update ranging. Going forward for new batches can also all be marked as HW1.1 with the faster range update.
It will only make it a better product with future sales of the meters. And I’m sure someone will review it with the faster update range showing the meter with all the bugs fixed as well. And this way you get some of the faster update meters in people’s hands to work out any bug that might inadvertently happen from the faster update range improvements for hands on testing.

And for those that have the ability to calibrate the meter they can also load hardware version 1.1 firmware and do the calibration themselves.

If an open source firmware does happen, then who ever is working on the firmware will need to be aware of the different hardware versions.  This is a common thing when hardware changes happen anyway.


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Offline mikeselectricstuff

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Re: EEVBlog 121GW Discussion thread
« Reply #136 on: January 24, 2018, 11:47:03 am »
Presumably the cal issue is that they need to do measurement differently, so different cal data is needed.

This could be handled by the firmware looking to see if the new format data is present, and only using the newer ranging method if so. A user could choose to recal to enable this if they have the facility.

Another approach for a user to recal would be simply to use old FW to set a multiturn trimmer to the required cal value, update the FW, then use the trimmer to recal.
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Offline Halcyon

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Re: EEVBlog 121GW Discussion thread
« Reply #137 on: January 24, 2018, 11:47:20 am »
How is the range switch modification going to be implemented? Who is doing the replacement for the US meters, and will you send replacement parts to customers who've already received theirs?

Dave has answered this in the "Issues" thread, see below...

The switch on my meter (#000499) is also wobbly and has the problem described here.
I took it apart, and contacts and pcb looked ok. After I put it back together it worked allright for a while, but now it's back and I have to fiddle with the switch again to get it to display correct readings. :-BROKE
Dave, once UEi figures out a fix, will you send out a replacement part?

Yes we'll have to do that for those existing shipments who have problems.
 

Offline Scottjd

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Re: EEVBlog 121GW Discussion thread
« Reply #138 on: January 24, 2018, 12:22:01 pm »
Presumably the cal issue is that they need to do measurement differently, so different cal data is needed.

This could be handled by the firmware looking to see if the new format data is present, and only using the newer ranging method if so. A user could choose to recal to enable this if they have the facility.

Another approach for a user to recal would be simply to use old FW to set a multiturn trimmer to the required cal value, update the FW, then use the trimmer to recal.

True, but just because a meter is calibrated again doesn’t mean the format of the cal data stored in the eeprom is going to be in a different format. Assuming it will be the same formate, just different numbers to the firmware to read I not sure the firmware could determine what is an old cal data vs re-cal for the faster  update rate. And then theirs the issue of space, adding extra code if timcoild determine the difference between new and old cal data woild take up more space. And we don’t know how much is available as it currently is.
Besides, my thought behind it was technical the updated switch is a hardware change also. They would need someway to mark what meters have the updated switch bs the older one. This way if the issue comes up again they will know if it was an older meter first batch, or a fixed one that the problem re-surfaced on.
I guess when others get the parts to fix it themselves thenpart bag might want to include a self repair sticker unless UEI plans to stamp the under side of the switch with s different code or add a code to the mold?
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Offline EEVblog

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Re: EEVBlog 121GW Discussion thread
« Reply #139 on: January 24, 2018, 12:24:28 pm »
Ok, so your saying the meters are now in the US, and UEI is taking them to fix the range switches. Will UEI be shipping them, or will they get shipped again to the reshipper in the US and then make it to the customers. Or did you can the reshipper and UEI will be shipping the US meter now?

They will now ship direct from Kane Test (UEi) in the US.

Quote
I have an idea, it’s not uncommon to have 2 different firmwares for different hardware releases.
As a “Thank you for being patient” can the US customers request maybe UEI can update the auto range speed on the US meters and mark them hardware version 1.1. Since it will be at the manufacturer I’m sure they can calibrate for the faster update ranging. Going forward for new batches can also all be marked as HW1.1 with the faster range update.

There is no change in actual PCB hardware, it's a small mod to the tolerance range switch parts.

Quote
And for those that have the ability to calibrate the meter they can also load hardware version 1.1 firmware and do the calibration themselves.

I've said this before, we will not release firmware that requires a recal. Most people are NOT  in a position to calibrate their own meters.
To do so would require screwing existing customers, or maintaining two version of the firmware. Either solution is not acceptable.
 

Offline dcac

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Re: EEVBlog 121GW Discussion thread
« Reply #140 on: January 24, 2018, 12:44:28 pm »
Another approach for a user to recal would be simply to use old FW to set a multiturn trimmer to the required cal value, update the FW, then use the trimmer to recal.

That would also make a great video for Dave to show this procedure.

But I can see Dave’s problem - from the manual: “Factory calibration will be VOID if this function is used”

So that warranty will be lost on the already delivered units. So I guess then the only way is to issue a recall and who's going to cover that cost? If spread out over all backers (who bought a 121GW) what money are we talking about?

 

Offline hwti

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Re: EEVBlog 121GW Discussion thread
« Reply #141 on: January 24, 2018, 12:49:57 pm »
Dave posted the schematic in the firmware thread, but I reply here since my questions would be off-topic there :
Here is the schematic which may help
David2 is working on seeing what we can provide in terms of documentation to help people who want to write their own firmware.
http://www.eevblog.com/files/121GW%20EEVBlog%20Circuit%20diagram.pdf
Why are Q13/Q16 (and Q14/Q15 if they were populated) used ?
To set the power-on (floating GPIO ?) state, a pull-up resistor would be enough.
The invert could have been done in software.

What would the B/Y channel of U14 would do if it was connected ?
It would connect TP11 to TP13 if DCmV_CTL (not used elsewhere) is high :-//

Is it safe to let 4053 logic input pins floating (C pin of U11, A pin of U14 if it was populated) ?
Usually it's not recommended, so unless the 4053 is special it's strange.
 

Offline logictom

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Re: EEVBlog 121GW Discussion thread
« Reply #142 on: January 24, 2018, 01:21:24 pm »
Regarding the specs of the meter, in the manual it lists the ranges:



So what is the resolution and accuracy for 501uA to 4999uA?
 

Offline EEVblog

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Re: EEVBlog 121GW Discussion thread
« Reply #143 on: January 24, 2018, 01:40:00 pm »
Regarding the specs of the meter, in the manual it lists the ranges:



So what is the resolution and accuracy for 501uA to 4999uA?

They use the 5mA range.
 

Offline IanB

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Re: EEVBlog 121GW Discussion thread
« Reply #144 on: January 24, 2018, 02:06:13 pm »
In other words, the table is like this: (?)

Range    Resolution, Accuracy  Burden Voltage
50 µA    1 nA, ±1.5%+15  100 µV/µA
500 µA    10 nA, ±1.5%+15  100 µV/µA
5 mA    0.1 µA, ±0.25%+5  2 mV/mA
50 mA    1 µA, ±0.25%+5  2 mV/mA
0.5 A    10 µA, ±0.75%+15  0.03 V/A
10 A    1 mA, ±0.75%+15  0.03 V/A
« Last Edit: January 24, 2018, 02:12:54 pm by IanB »
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Offline hwti

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Re: EEVBlog 121GW Discussion thread
« Reply #145 on: January 24, 2018, 02:36:49 pm »
Dave, http://www.eevblog.com/files/121GW%20EEVBlog%20Circuit%20diagram.pdf is rev 1752, and my actual meter is rev 1745 on the PCB.
Are there any différences ?

The rev 1705 and 1720 from your "121GW Final Test Unit Inspection" video had U14 for example.
 

Offline Scottjd

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Re: EEVBlog 121GW Discussion thread
« Reply #146 on: January 24, 2018, 04:10:54 pm »
The rev 1705 and 1720 from your "121GW Final Test Unit Inspection" video had U14 for example.
Are you referring to the video with them all on the table, and the close up shots? I saw that one as 1745 with u14 missing also. Or are you referring to another video?
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Offline logictom

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Re: EEVBlog 121GW Discussion thread
« Reply #147 on: January 24, 2018, 04:45:00 pm »
Regarding the specs of the meter, in the manual it lists the ranges:



So what is the resolution and accuracy for 501uA to 4999uA?

They use the 5mA range.

If that is the case, why is it listed as 5 to 50 mA instead of that actual range of 0.5 to 50mA? Am I missing something simple here? ???
 

Offline amspire

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Re: EEVBlog 121GW Discussion thread
« Reply #148 on: January 24, 2018, 04:55:01 pm »
Regarding the specs of the meter, in the manual it lists the ranges:



So what is the resolution and accuracy for 501uA to 4999uA?

They use the 5mA range.

If that is the case, why is it listed as 5 to 50 mA instead of that actual range of 0.5 to 50mA? Am I missing something simple here? ???
You are missing something. Multimeter specifications always refer to the ranges - not to currents or voltages you are measuring. So this table is talking about the 50uA to 10A ranges.

If you want to measure 500uA, you can use the 500uA range, the 5mA range, the 50mA range, the 0.5A range, or the 5A range. The 10A is just a bit too far to see the 500uA. Each of these ranges will have its own accuracy that you can read from the table.

Why would you want to measure 500uA on the 0.5A range? The reason would be the burden voltage. For that range, the voltage drop across the multimeter (ignoring the 10A fuse) is 0.03V/A or at 500uA, that is only 15uV! The accuracy of the 500uV measurement would only be about 30%, but that can often be good enough.
« Last Edit: January 24, 2018, 05:08:23 pm by amspire »
 
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Offline hwti

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Re: EEVBlog 121GW Discussion thread
« Reply #149 on: January 24, 2018, 05:28:42 pm »
The rev 1705 and 1720 from your "121GW Final Test Unit Inspection" video had U14 for example.
Are you referring to the video with them all on the table, and the close up shots? I saw that one as 1745 with u14 missing also. Or are you referring to another video?
The video I'm referring to is unlisted, but easy to find by its title.
But those older revision don't really matter, it's just to show there are differences, and not limited to the changes needed to pass certification.

What matters is we have rev 1745 meters, so perhaps we need rev 1745 schematic, and not rev 1752 which might be different.
 
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