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Brymen Crest and Min/Max Function VDC Capability

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joeqsmith:

--- Quote from: splat2030 on September 18, 2022, 04:22:55 pm ---
--- Quote from: joeqsmith on September 18, 2022, 03:22:24 pm ---If you check the manual for the meter used in the video you linked, it should be fast enough to capture that 13.5ms dip.   

https://assets.fluke.com/manuals/87______umeng0800.pdf

The Brymen BM789 and BM869s can both easily measure it (yes in DC crest mode).   Guessing they offer other meters that could measure it as well.   I looked at their automotive meter.  The one thing I did not like about it was it would not save every parameter and required more fiddling than I would have liked.   

**
Should add, when I wrote both meters can easily measure this,  I set up a one-shot pulse (single pulse) that idles at 11V, then jumps to 16V for 5ms, then down to 6V for 5ms, then returns to 11V.

--- End quote ---

I have also been looking at the BM789, and the crest function appears to have the best specs. of all the Brymen meters. Manual states it can record with an accuracy of +100 digits at a duration of .35ms, however, the tolerance would still be quite large at +/- 1.0 volts when measuring 12.6 volts in 6000 count mode. What kind of accuracy did you see when you took those measurements?

Would it be possible for you to test the minimum signal duration in VDC for the regular min/max mode as well? Manual states that min/max records 10X/second or 100ms, but also states that the min signal duration is 300ms which seems pretty slow compared to their spec for the BM839 at 200ms. Very interested to know how close this would come to the spec.

--- End quote ---

The min/max function on both meters (BM869s/789) would be far too slow to measure your 13.5ms.  For accuracy, I would defer to the manual.     

I have a Fluke 189 which has something called a Fast Min/Max mode.  This is a 5000 count mode with +/-100 count accuracy.    I don't own the 87 referenced in your video.  Looking at the manual they show a +/-40 count but then have a typical of +/-100 count for some modes. 

https://dam-assets.fluke.com/s3fs-public/87______umeng0800.pdf

joeqsmith:

--- Quote from: splat2030 on September 18, 2022, 04:22:55 pm ---The interesting thing I noticed after watching that video again closer is that he just pressed the min/max button one time, which would have put the Fluke 87 in the 100ms nominal response setting, and not the peak 1ms setting. This setting requires a minimum signal duration of 200ms per the Fluke manual from your link, so I don't think his reading of 9.96 volts is actually the true minimum voltage if the signal is only 13.5ms.

--- End quote ---

Guessing that is true but he may know that and the number he tossed out for a minimum was based on that.  Hard to say.   You could write them and ask.   

splat2030:

--- Quote from: Fungus on September 18, 2022, 04:54:31 pm ---
--- Quote from: splat2030 on September 18, 2022, 03:59:52 pm ---It seems that min/max on any of these meters is going to be much too slow, however, I am concerned about the accuracy when using the crest function. BM829s Manual states +250 digits for signals greater than 1ms in crest, and I would be in the 60.00V range to measure 12.6 volts. This would result in a tolerance of approx +/- 2.5 volts (.01*250), which pretty much would make it useless for this reading with that poor of accuracy.

--- End quote ---

My Brymen BM857s is +100 digits on 50,000 counts. That's 0.1V accuracy on the 50V range.

It's one of Brymen's "professional" meters (ie. designed to be thrown in toolboxes) and it only costs 10 Euros more than the BM829s.

https://brymen.eu/shop/bm857s/

I'm sure there's other Brymens with similar specs.

--- End quote ---

It seemed like all of the meters I have looked at so far state that they revert to 4 digit display when in the crest/peak mode. I took a look at the manual for the BM857s, and oddly it doesn't list any specs for the meter at all. I had to pull the catalog brochure which states +100ms for changes greater than .8ms, but does not specify which scale the meter uses. Can you confirm with your meter that when you put it in crest mode you have a 5 digit display rather than 4 digit?

Neither the manual nor catalog brochure give any specs on the performance of the regular min/max function, did yours come with any other documentation that lists this?

splat2030:

--- Quote from: joeqsmith on September 18, 2022, 05:30:31 pm ---
--- Quote from: splat2030 on September 18, 2022, 04:22:55 pm ---
--- Quote from: joeqsmith on September 18, 2022, 03:22:24 pm ---If you check the manual for the meter used in the video you linked, it should be fast enough to capture that 13.5ms dip.   

https://assets.fluke.com/manuals/87______umeng0800.pdf

The Brymen BM789 and BM869s can both easily measure it (yes in DC crest mode).   Guessing they offer other meters that could measure it as well.   I looked at their automotive meter.  The one thing I did not like about it was it would not save every parameter and required more fiddling than I would have liked.   

**
Should add, when I wrote both meters can easily measure this,  I set up a one-shot pulse (single pulse) that idles at 11V, then jumps to 16V for 5ms, then down to 6V for 5ms, then returns to 11V.

--- End quote ---

I have also been looking at the BM789, and the crest function appears to have the best specs. of all the Brymen meters. Manual states it can record with an accuracy of +100 digits at a duration of .35ms, however, the tolerance would still be quite large at +/- 1.0 volts when measuring 12.6 volts in 6000 count mode. What kind of accuracy did you see when you took those measurements?

Would it be possible for you to test the minimum signal duration in VDC for the regular min/max mode as well? Manual states that min/max records 10X/second or 100ms, but also states that the min signal duration is 300ms which seems pretty slow compared to their spec for the BM839 at 200ms. Very interested to know how close this would come to the spec.

--- End quote ---

The min/max function on both meters (BM869s/789) would be far too slow to measure your 13.5ms.  For accuracy, I would defer to the manual.     

I have a Fluke 189 which has something called a Fast Min/Max mode.  This is a 5000 count mode with +/-100 count accuracy.    I don't own the 87 referenced in your video.  Looking at the manual they show a +/-40 count but then have a typical of +/-100 count for some modes. 

https://dam-assets.fluke.com/s3fs-public/87______umeng0800.pdf

--- End quote ---

I was wondering how close you got to the true voltage value with the BM-789 in crest mode when you were measuring the 11V-16V pulse? Considering my calculation shows a tolerance of +/-1 volt when in the 60.00volt scale, was the meter actually capable of returning a value closer to actual than the stated tolerance?

My confidence in the accuracies of regular min/max reported in the manual without 3rd party verification isn't great at this point considering that the two Bryman meters tested at the website referenced by mqsaharan (BM-829s, and BM-869s) both were way off compared to spec. The BM-829s took 570ms vs 50ms stated in the spec, and the BM869s took 350ms vs 50ms stated on the website. The BM789 seems to be their newest meter and has a much more detailed spec. for the min/max function in the manual, so I am curious whether this meter will actually perform closer to the spec. than the others. I will be using the regular min/max for other applications, so I would like to ensure whatever meter I get performs well in this function in addition to the crest/peak function.

https://lygte-info.dk/review/DMMBrymen%20BM829s%20UK.html

https://lygte-info.dk/review/DMMBrymen%20BM869s%20UK.html

Fungus:

--- Quote from: splat2030 on September 19, 2022, 12:54:26 am ---I had to pull the catalog brochure which states +100ms for changes greater than .8ms

--- End quote ---

It's the "datasheet", not the "brochure", and it's +/-100 digits.  :)


--- Quote from: splat2030 on September 19, 2022, 12:54:26 am ---but does not specify which scale the meter uses. Can you confirm with your meter that when you put it in crest mode you have a 5 digit display rather than 4 digit?

--- End quote ---

If I manual range to the 50V mode then press "crest" I get two digits before and two digits after the decimal point.

I find it very hard to believe the accuracy is 1V though, that would be completely useless.

I think we're not fully understanding the phrase "+100 digits for changes greater than .8ms".

I can understand that a change less than .8ms could be missed but what's meant by that wording?  :-//

I could do some measurement experiments but they won't prove much until that's cleared up.

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