Author Topic: New EEVblog BM786 Multimeter  (Read 57937 times)

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Online 2N3055

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Re: New EEVblog BM786 Multimeter
« Reply #50 on: October 17, 2020, 12:03:12 pm »
On my multimeter (UT71D), the voltage AC+DC is always converted to true RMS by the AD636.

Vrms= Avg x [Vin^2/Vrms]

If AC only is required, Vin is routed through a capacitor before reaching the true RMS converter.
The AC/AC+DC switch works on the V AC selector position only.
The DC component is read on the V DC selector position.

You are correct, RMS converter by definition converts AC+DC value by definition (it just a waveform to them). So if you DC couple them you get AC+DC, if you AC couple them you get AC RMS only.

People are probably confused by DUAL display mode on (for instance BM869S) that shows AC RMS and AC+DC RMS od screen at the same time... Those two are separate measurements that need to be switched back and forth between modes.

 

Offline ogdento

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Re: New EEVblog BM786 Multimeter
« Reply #51 on: October 17, 2020, 11:50:51 pm »
Too bad about the 789, but I guess it really doesn't matter... the 786 is fantastic for my electronics tinkering and would probably never leave my bench anyway. (Not that it couldn't handle it, but there's no reason to drag it under the house or into the attic).  The old bm257 has low-z/ef and can sit in the tool bag for the household wiring jobs.
 

Offline multiJ

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Re: New EEVblog BM786 Multimeter
« Reply #52 on: October 22, 2020, 12:12:42 pm »
joeqsmith has in hand the new Brymen 7series multimeter(s?) for testing  :)

at 9.04
 
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Online joeqsmith

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Re: New EEVblog BM786 Multimeter
« Reply #53 on: October 22, 2020, 06:43:50 pm »
joeqsmith has in hand the new Brymen 7series multimeter(s?) for testing  :)
...

The one I pulled out is the BM786.  As I mentioned, Brymen does not yet have the generic front covers for it.  Rather than wait, the meter was shipped with a different cover, similar to what Dave has shown.   The PCB, firmware and back case half are all the release versions so as far as making a review we should be good.   I was very clear of my intent and Brymen was onboard. 

Brymen has stood behind their products from day one.  Like me, I think they like seeing how their designs stack up against other brands on a level playing field.   I'm looking forward to seeing how it holds up.   
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
Software, documentation and test reports for the low cost NanoVNA & V2 Plus 4 may be found here:
https://github.com/joeqsmith
 
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Offline EEVblog

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Re: New EEVblog BM786 Multimeter
« Reply #54 on: October 22, 2020, 09:42:26 pm »
joeqsmith has in hand the new Brymen 7series multimeter(s?) for testing  :)
...
The one I pulled out is the BM786.  As I mentioned, Brymen does not yet have the generic front covers for it.  Rather than wait, the meter was shipped with a different cover, similar to what Dave has shown.   The PCB, firmware and back case half are all the release versions so as far as making a review we should be good.

I just got the final blue branded version, was going to do an unboxing video, but here you go. Note the decal stickers on the red proto.
 
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Online joeqsmith

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Re: New EEVblog BM786 Multimeter
« Reply #55 on: October 23, 2020, 02:07:04 am »
I'm not too concerned with them using stickers to change the lettering on this meter.  The only time it would be a problem is during my chemical tests.   I will just avoid those areas. 
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
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Offline EEVblog

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Re: New EEVblog BM786 Multimeter
« Reply #56 on: October 23, 2020, 03:16:46 am »
I'm not too concerned with them using stickers to change the lettering on this meter.  The only time it would be a problem is during my chemical tests.   I will just avoid those areas.

I'm not sure a non-sticker red version exists, they went straight to blue for me.
So likely the one you got is one of a bunch they built to have sent to UL for testing. Should be identical to the shipped blue version but I haven't opened mine yet to confirm. My internal photos above are from my red sticker version.
 
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Online joeqsmith

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Re: New EEVblog BM786 Multimeter
« Reply #57 on: October 23, 2020, 12:48:55 pm »
I'm not too concerned with them using stickers to change the lettering on this meter.  The only time it would be a problem is during my chemical tests.   I will just avoid those areas.

I'm not sure a non-sticker red version exists, they went straight to blue for me.
So likely the one you got is one of a bunch they built to have sent to UL for testing. Should be identical to the shipped blue version but I haven't opened mine yet to confirm. My internal photos above are from my red sticker version.

From above:
Quote
As I mentioned, Brymen does not yet have the generic front covers for it.  Rather than wait, the meter was shipped with a different cover, similar to what Dave has shown.   The PCB, firmware and back case half are all the release versions so as far as making a review we should be good.

I could have waited for the final cover but Brymen was fine with me showing it with the taped cover.  I plan to start working on it over the weekend.  Being a Brymen, I am not anticipating anything but a boring review where the meter just works... :-DD   
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
Software, documentation and test reports for the low cost NanoVNA & V2 Plus 4 may be found here:
https://github.com/joeqsmith
 
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Offline radiolistener

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Re: New EEVblog BM786 Multimeter
« Reply #58 on: October 23, 2020, 01:25:34 pm »
The first thing that catches my eye is that this new DMM has 60000 count instead of 500000 count like BM-867/869.

What is the reason to use less than 500000 count chipset for modern DMM?
 

Offline multiJ

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Re: New EEVblog BM786 Multimeter
« Reply #59 on: October 23, 2020, 01:30:56 pm »
The first thing that catches my eye is that this new DMM has 60000 count instead of 500000 count like BM-867/869.

What is the reason to use less than 500000 count chipset for modern DMM?

Cost?
 

Offline radiolistener

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Re: New EEVblog BM786 Multimeter
« Reply #60 on: October 23, 2020, 01:44:59 pm »
Cost?

I bought BM867 for about 150 USD.
This BM786 price is also 150 USD.


But BM867 has 500000 count mode, while BM786 has just 60000 count.
 

Offline Wytnucls

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Re: New EEVblog BM786 Multimeter
« Reply #61 on: October 23, 2020, 02:15:26 pm »
500,000 count is just for higher resolution on DC volt. It does not improve your accuracy.
Some may find it useful to watch a battery draining slowly, for instance.
Not a deal breaker for most users.
 

Online 2N3055

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Re: New EEVblog BM786 Multimeter
« Reply #62 on: October 23, 2020, 02:25:59 pm »
Cost?

I bought BM867 for about 150 USD.
This BM786 price is also 150 USD.


But BM867 has 500000 count mode, while BM786 has just 60000 count.

To me bigger difference is dual display vs single display. It is more of a refreshed addition to of 857/9 series..
 

Offline coromonadalix

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Re: New EEVblog BM786 Multimeter
« Reply #63 on: October 23, 2020, 02:28:43 pm »
I always hate how people see "that 500k  count mode",  its an real 50k count      with an added bonus ...   

I love the 60k count of the 786,  maybe a 600k count hack with another lcd      loll

We love huge display counts  loll


Great job for the 786  Dave



 

Offline Electro Fan

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Re: New EEVblog BM786 Multimeter
« Reply #64 on: October 23, 2020, 02:35:32 pm »
786 is a friendlier size and weight than the 867.
 

Online joeqsmith

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Re: New EEVblog BM786 Multimeter
« Reply #65 on: October 23, 2020, 03:16:34 pm »
I also use the BM869s high resolution mode.  It's too bad it's not supported in all modes.    That Gossen Ultra or what ever they call it now is a 300,000 count meter for about $850.   Normally I am using the old bench meters.    I'm also a fan of dual and tri-display meters, assuming they actually display something useful. 

***
Actually, what I should have wrote about the 500K mode is it would have been nice to have a sticky mode where it is always active.
« Last Edit: October 23, 2020, 09:23:03 pm by joeqsmith »
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
Software, documentation and test reports for the low cost NanoVNA & V2 Plus 4 may be found here:
https://github.com/joeqsmith
 
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Offline EEVblog

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Re: New EEVblog BM786 Multimeter
« Reply #66 on: October 23, 2020, 09:15:26 pm »
Cost?
I bought BM867 for about 150 USD.
This BM786 price is also 150 USD.
But BM867 has 500000 count mode, while BM786 has just 60000 count.

$150 is not the normal price for the BM867
The BM786 is smaller and has features not found on the BM867.
I can assure you the FOB cost of the BM786 is lower.
Having the extra digit requires more segments on the LCD, and possibly a bigger or extra driver chip as a result, and a bigger case or smaller font.
500,000 count is no use for what appears to be the intended market of a Fluke 70 series competitor.
There might also be other compromises.
 

Offline EEVblog

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Re: New EEVblog BM786 Multimeter
« Reply #67 on: October 23, 2020, 09:18:37 pm »
I always hate how people see "that 500k  count mode",  its an real 50k count      with an added bonus ...   
I love the 60k count of the 786,  maybe a 600k count hack with another lcd      loll

Remember, 20% of the time the 60,000 count BM786 is going to have the same resolution as the 500,000 count BM876, and at better accuracy.
« Last Edit: October 23, 2020, 11:58:33 pm by EEVblog »
 
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Offline rsjsouza

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Re: New EEVblog BM786 Multimeter
« Reply #68 on: October 24, 2020, 11:09:35 am »
Cost?
I bought BM867 for about 150 USD.
This BM786 price is also 150 USD.
But BM867 has 500000 count mode, while BM786 has just 60000 count.

$150 is not the normal price for the BM867
I have been following the prices of this model for a few years and the price at the tme site has been stuck at US$156.00.
https://www.tme.com/us/en-us/details/bm867/portable-digital-multimeters/brymen/bm867s/

500,000 count is no use for what appears to be the intended market of a Fluke 70 series competitor.
The 500k count is just a trend viewer - useful for charges and discharges, but with very loose accuracy. Something similar to the 20k count mode of the 87V.

What I really want to see is if the BM786 in 60k count is snappier than Keysight's U1282A.
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Oh, the "whys" of the datasheets... The information is there not to be an axiomatic truth, but instead each speck of data must be slowly inhaled while carefully performing a deep search inside oneself to find the true metaphysical sense...
 
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Online Fungus

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Re: New EEVblog BM786 Multimeter
« Reply #69 on: October 24, 2020, 11:55:16 am »
What I really want to see is if the BM786 in 60k count is snappier than Keysight's U1282A.

Check out Joe's video:

https://www.eevblog.com/forum/testgear/hear-kitty-kitty-kitty-nope-not-that-kind-of-cat/msg3293014/#msg3293014
 
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Online joeqsmith

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Re: New EEVblog BM786 Multimeter
« Reply #70 on: October 24, 2020, 04:23:43 pm »
The 500k count is just a trend viewer - useful for charges and discharges, but with very loose accuracy. Something similar to the 20k count mode of the 87V.

What I really want to see is if the BM786 in 60k count is snappier than Keysight's U1282A.
I tend to agree.  It's common that I am more interested in relative numbers than absolute.  How much something drifts for example.   It's proven to be useful. 
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
Software, documentation and test reports for the low cost NanoVNA & V2 Plus 4 may be found here:
https://github.com/joeqsmith
 

Offline rsjsouza

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Re: New EEVblog BM786 Multimeter
« Reply #71 on: October 24, 2020, 10:21:59 pm »
The 500k count is just a trend viewer - useful for charges and discharges, but with very loose accuracy. Something similar to the 20k count mode of the 87V.

What I really want to see is if the BM786 in 60k count is snappier than Keysight's U1282A.
I tend to agree.  It's common that I am more interested in relative numbers than absolute.  How much something drifts for example.   It's proven to be useful.
Yes, for that the 500k count mode is great.

BTW, congratulations on getting the new Brymen as an exclusive. I'll watch the video later.
« Last Edit: October 24, 2020, 10:23:52 pm by rsjsouza »
Vbe - vídeo blog eletrônico http://videos.vbeletronico.com

Oh, the "whys" of the datasheets... The information is there not to be an axiomatic truth, but instead each speck of data must be slowly inhaled while carefully performing a deep search inside oneself to find the true metaphysical sense...
 

Offline EEVblog

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Re: New EEVblog BM786 Multimeter
« Reply #72 on: October 24, 2020, 11:43:31 pm »
What I really want to see is if the BM786 in 60k count is snappier than Keysight's U1282A.

It'll do 10 times/sec updating in capture mode, so fast it's a bit disconcerting.
 

Offline rsjsouza

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Re: New EEVblog BM786 Multimeter
« Reply #73 on: October 25, 2020, 10:49:19 am »
What I really want to see is if the BM786 in 60k count is snappier than Keysight's U1282A.

It'll do 10 times/sec updating in capture mode, so fast it's a bit disconcerting.
Thank you. I meant the settling rate of the autorange but that is quite a good rate as well. 

After watching Joe's video, I could tell the two seem to use different approaches for the autorange. I did a side-by-side comparison timing with the ohms and capacitance ranges (the ones where the lag is larger). Joe mentioned 15s to settle on the 40M measurement, while my Keysight was about 2s. This was becoming less dramatic as resistance decreased, with a crossing point of performance somewhere (didin't verify) and  the Keysight becomes slower to the point of taking almost 6s to read my 33 ohms resistor, while the Brymen becomes significantly faster.

Conductivity tests were similar in speed (perhaps because there are not many ranges to cycle).

I also saw an edge for the Keysight on the capacitance - not very dramatic, but both seem to pale in comparison to others such as the 87V, the UT61E or the U1273A. Voltages and current seemed quite equivalent.

I took these timings from Joe's video, thus this is not a definitive conclusion to the autorange performance at all.
Vbe - vídeo blog eletrônico http://videos.vbeletronico.com

Oh, the "whys" of the datasheets... The information is there not to be an axiomatic truth, but instead each speck of data must be slowly inhaled while carefully performing a deep search inside oneself to find the true metaphysical sense...
 

Online joeqsmith

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Re: New EEVblog BM786 Multimeter
« Reply #74 on: October 25, 2020, 01:52:30 pm »
That's correct.  It's very slow in resistance with values over 10M, on the order of 10-15 seconds to settle with the 40M.  From the video, you can also see the 150pF took a fair bit of time but then so did the 100uF.   Part 2 will include a few more speed comparisons.       
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
Software, documentation and test reports for the low cost NanoVNA & V2 Plus 4 may be found here:
https://github.com/joeqsmith
 
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