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| Brymen BM789 |
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| joeqsmith:
--- Quote from: Neutrion on September 14, 2021, 02:41:01 pm ---Sudden unforeseen levels of voltages are also real life issues, which you don't want, but it just happens. --- End quote --- :-DD :-DD :-DD Don't I know it. Again, it's why I started making reviews showing something besides unboxing them, talking about my years as being a expert in flipping burgers to validate my opinions and then giving them all five stars. I'm looking for products that survive, not that can make an accurate measurement while being exposed to these various tests. --- Quote from: Neutrion on September 14, 2021, 02:41:01 pm ---But we are arguing here about whether it is the intended use of the meter: No it is not (except if one wanted to buy the meter for the mentioned ripple measurement.) But the real question in the whole topic is whether the missing "OL" indication is solveable in FW. According to Dave possibly not, 2N3055 provided a possible technical description why not, Joe seems to agree?. --- End quote --- Sorry, I wasn't aware we were arguing. I would have no way to know if ANY meter would show over range under all conditions when set to their ACmV function. Again, it's not something I would normally do and if people agree with me or not is of little concern. My collection of DMMs is mostly limited to ones that survived my tests. Others may offer a broader spectrum to avoid adding bias. I have little doubt if anyone wanted to try it we would see some problems. I doubt you would need to run them up to the 30V you mention. |
| AndrewBCN:
--- Quote from: bdunham7 on September 14, 2021, 02:37:04 pm ---The meter is unable to read AC ripple on a DC bias in the mVAC range, such as a very common PSU ripple measurement. How is that not a limitation? As for the value of the information, I don't know why you think it has zero value. It certainly is instructive about how to avoid a particular issue in using the meter. Of course, as I posted, it's in the manual too, but who reads those? --- End quote --- Personally I don't think a multimeter is the best tool to observe and measure PSU ripple and noise (and transients), I believe a DSO provides a lot more information. In any case, as you noted, it's right there in the BM789 manual: in the ACmV (600mV) and AC+DCmV ranges, peak value including DC offset must be under 1000mV. So perhaps people who are trying to find a fault in a multimeter should read the manual first :-DMM? |
| joeqsmith:
As I understand it, for the OP it all comes down to if the over range indicator works under ALL conditions with the meters set specifically to their ACmV function which may not always be found in the manual. I think this is why they are suggesting someone try running a test. Again, for me the outcome isn't a big deal one way or the other. I can believe we would find some cases. The problem I see when looking for these fringe cases is the OP has not provided any constraints. I suspect it's more their general curiosity than anything. Maybe limit it to the 40-500Hz they mentioned and keep it within +/-2 Volts so everyone could join in the fun? |
| AndrewBCN:
I have one suggestion for the firmware engineers at Brymen: please program the BM789's MCU to display the following characters when the ACmV or AC+DCmV ranges are selected and an input peak voltage including DC offset > 1000mV is detected: RTFM Honestly, why didn't they think of that? :-DMM |
| bdunham7:
--- Quote from: AndrewBCN on September 14, 2021, 03:44:18 pm ---Personally I don't think a multimeter is the best tool to observe and measure PSU ripple and noise (and transients), I believe a DSO provides a lot more information. --- End quote --- Clearly this DMM is not the best tool for that, but there are many others that do just fine. Whether a DSO is necessary or better depends on what you are doing. What about a quick go/no-go test when a DSO isn't handy? What if the power supply ripple is below the noise floor of the DSO? For me personally, this would be a routine test and I would typically only break out the scope if my DMM indicates a ripple issue or there is some other strange problem. --- Quote ---So perhaps people who are trying to find a fault in a multimeter should read the manual first :-DMM? --- End quote --- A documented limitation is still a limitation. |
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