The hanging part has nothing to do with using the SD card and BLE at the same time. It happened before, but I don't remember the circumstances. I think it was again on VA, but I'm not sure.
You are right about the logging equipment, but the whole idea of buying this DMM is using it for it's special features - BT, SD logging, low burden voltage, and they all don't work reliably.
You should be aware that there are some major problems with the VA mode. This was seen with the prototype and 2+ years later has yet to be addressed.
You should be aware that there are some major problems with the VA mode. This was seen with the prototype and 2+ years later has yet to be addressed.
If you are talking about the adding of burden voltage - that's not a problem. Also it's only a problem if you want to measure load power. I am measuring power supply (in my case battery) power. Every measuring instrument has imperfections and as long as you know about them - you can workaround them. The problem however when it starts freezing - that's not a normal DMM flow, it's a bug.
But yes, I agree that reversing the current probes in VA mode should be in the manual - it's a nice idea how to measure load power better (not power out of the supply).
As I said before they underestimated the firmware complexity ... anyway for +2 years it's impossible that more than 2 guys worked at this , or maybe one just stood and watched the other
With David2 now out of the picture, I doubt you will see much effort being put into the application side.
With David2 now out of the picture, I doubt you will see much effort being put into the application side.
That was never the plan. We got the app to a good refined working point and released it as fully open source software. If people want to improve upon it and add features they can, but we never had any plans to extend it ourselves beyond what it already is.
If this were true, you would not be posting here for help.
Why criticise the original plan? It's not as if Dave kept it secret. Besides, as Dave has stated, software isn't his forte.
All we need is for others who are better equipped to develop the App to take up the challenge. Then things can improve.
The app is not the biggest deal. If the firmware is working fine there will be someone to develop an app. If the firmware is not working there is no point of developing an app.
If this were true, you would not be posting here for help.
I'm not posting here for help. I'm reporting bugs.
Is there any way to log data with this DMM in a stable way?
https://www.eevblog.com/forum/blog/eevblog-1157-transistor-zener-clamp-circuit/msg2043871/#msg2043871
https://www.eevblog.com/forum/blog/eevblog-1157-transistor-zener-clamp-circuit/msg2037994/#msg2037994
Here are Dr Franks’s posts he made just after Dave released his video discussing the advantage of the double transistor zener type clamp, and that this now would be implemented in 121gw.
Now there’s nothing wrong with Dave’s video as such, I think he does a great job presenting it. But it’s very hard to see how Dr Frank could have made it any clearer that this clamp solution would not work as transients at +/- 25V now could reach U9 the HEF4053. Although it of course depends on exactly how you implemented this new clamp, U9 would have a very hard time handling these voltages. There were also quite a few other members in that thread voicing their concerns.
Still the clamp change went ahead and new HW revision of 121gw released, and it seems it‘s this revision Joe received with the two production meters he recently bought. And anyone following Joe’s videos knows exactly how well this new clamp worked.
Anyway, I guess this also is an example of the (broken) “information age” we now live in, but still it’s things like this that's really frustrating as a 121gw owner, seeing perfectly valid and detailed feedback not really be taking into account.
Maybe some guys here shouldn't be too super-critical, because they simply had too high expectancy upfront.
On the other hand, I would have expected that Joe might have re-engineered and analysed the actual protection circuit, either for confirmation or disproof of my findings .. instead he just did his brute-force / destructive tests on the 121GW.
If you looked at those last couple of posts of that UL listed TPI meter I showed, there are no MOVs and the meter was easily damaged. I assume they don't need all the MOVs and fluff for UL be cause the meter does not need to be robust. It needs to be safe. This is the difference between what Frank is mentioning with following the standards. There are no robustness standards so rather than follow the safety standards, I branched out on my own to look at their robustness.
In the 121, it's anyone's guess what their goals were for robustness. I am guessing something along the lines of UNI-Tish was good enough. But they include the MOVs and basic parts.
So while they did make a change, they didn't consider the impact it would have on how robust the meter was. Or maybe they did and that was a very low priority. Your guess is as good as mine. One thing is certain is that it's now on par with many UNI-T products I have looked at.
If you looked at those last couple of posts of that UL listed TPI meter I showed, there are no MOVs and the meter was easily damaged. I assume they don't need all the MOVs and fluff for UL be cause the meter does not need to be robust. It needs to be safe. This is the difference between what Frank is mentioning with following the standards. There are no robustness standards so rather than follow the safety standards, I branched out on my own to look at their robustness.
In the 121, it's anyone's guess what their goals were for robustness. I am guessing something along the lines of UNI-Tish was good enough. But they include the MOVs and basic parts.
So while they did make a change, they didn't consider the impact it would have on how robust the meter was. Or maybe they did and that was a very low priority. Your guess is as good as mine. One thing is certain is that it's now on par with many UNI-T products I have looked at.As we know UEi already changed the design again, now using transistors with a VEB0 at about 16V and that will clamp close to this voltage instead of 25V as your production 1-2 probably had. And as manufactures usually aren't changing their design just for the fun of it, they at least seems to be trying for some level of ‘robustness’.
A basic robustness test I’ve seen Dave use a couple of times is to put mains 240VAC into whatever mode the mode switch can be placed in, perhaps for a couple of seconds or so. I do my damndest trying to avoid doing a “mistake” like that. But still not an unreasonable test to do and see if the meter survives. So in this scenario the meters clamps, PTC’s and other input series resistors have to cope with the stress resulting from about 340V peak to peak, there can of course be some nasty overlayed transients on top of that but unless you’re monitoring the VAC with a scope you have no clue if this is the case.
Anyway, I can’t really remember if Dave also did this test on the 121gw, but I think so, in its original configuration anyway with the 4007‘s. But has he also done it with the new clamp configuration i.e. to show that it’s just as robust as it was before. If it isn't perhaps mentioning this in the next user manual revision is a good idea.