Thanks for showing the video from Kainka Labs and also joeqsmith for his suggestion how to connect the 121GW in VA mode to avoid the problem of wrong VA readings.
Just for fun I did the same test with the Gossen Metrahit Energy. Same setup as in the video, 1V source, resistor 22 Ohm. The Gossen is connected as it should, gnd to gnd, voltage input to the +1V output of the source and the current input is connected to the resistor, the resistor is connected to 1V source.
The result is shown at picture 1
Then I changed GND and current input at the Gossen. Result is picture 2.
That means that the Gossen meter uses the same wiring in the power mode which joeqsmith suggested for the 121GW.
I did some experiments on power measurement with the 121GW and I observed the "correct" way to connect it to measure power consumed by a load resulted in a negative display value for the power.
At first I didn't like this, but actually you could argue that power consumed is negative and power produced is positive. So perhaps it is just a matter of human perspective rather than any technical limitation of the system?
Metrix MTX3293 actually shows negative VA in secondary VA mode... For instance it will show 5V, -100mA and -500mVA..
But it will be correct.
I just DLed the manual for this meter. Interesting enough, they don't provide many details for the VxA mode. There are no recommendations on how to connect it that I saw and there was no mention about the burden voltage when using this mode. I then looked for a video showing it but I only found one. The guy really doesn't provide any details other than to say how nice he thought it was. Is there an application note or better manual available for this meter?
That switch has been a nagging thing keeping me from buying.
That switch has been a nagging thing keeping me from buying.
Dave,
I just watched the latest mailbag. You mention a new version of the 121GW and working towards getting your rotary switch life cycle tester working again. I plan to do a full review of this meter which would include cycling the switch. If you are interested, I would be be willing to buy a couple of these meters now (assuming you are happy with the other changes to the hardware) and run the test for you.
It would be the 50K full cycle test like I have been running. It would be non-stop unless something were to go wrong and I decided to abort the test.
What's the max safe temperature for the K-type temperature probe provided with the meter?
Manual says 1350 C, but that's about the probe itself.
What about the coating of the probe wiring?
Sorry if I missed this but is the voltage and current for continuity test listed somewhere?
Someone is telling me that an STM32 can be damaged by DMM continuity checks...
For the 121GW I couldn't find it in the manual, but see this page:
https://lygte-info.dk/review/DMMEEVBlog%20121GW%20UK.html
2.1 V open and 0.57 mA shorted.
I'm hoping the eevblog team are on holidays, I broke a probe tip 12 days ago, emailed them that same day and I haven't heard back from the team on how to replace it, fingers crossed they will come back rested and send me a response.
I bought the 121GW because it looked promising (and it is) but also because of some other points:
- heavily supported by Dave
- upgradable/hackable
- Dave's enthusiasm
Now, it seems that the "soufflé est retombé" as we say in French. I would like to be proven the opposite, but except a few apparitions of the multi-meter in some videos, enthusiasm seems to be gone, upgrades are no longer available, no more reaction from any Dave.
Available resources have probably moved to the micro supply ... until the next project ? May a small team support several projects and keep enthusiasm for all of them?
No offense at all, only my feeling... Buying the GW121 was my own decision, it's working, I use it and I don't regret it. I was just hoping a bit more.
What were you expecting? Personally I feel the firmware is likely approaching the limits of the hardware so incremental change will naturally slow and be minor in nature.