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New EEVblog BM786 Multimeter

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Brumby:
As has been mentioned before, accuracy to 5 or 6 digits is rarely needed on most people's bench - but 5 or 6 digits of resolution are often very useful.

For example - If I have a reading of 4.5678V and when I alter the circuit somehow, the reading becomes 4.5675, then I have a pretty good idea the voltage went down - just a little.  Sometimes, that's exactly the bit of information you need.  The absolute accuracy could be out by 10%, but the change will still be a valid observation.

Fungus:

--- Quote from: radiolistener 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?

--- End quote ---

Simple: Because even 6000 counts is 0.016% accuracy. Supporting 6000 counts properly already requires very high precision components.

HKJ:

--- Quote from: Fungus on October 28, 2020, 06:20:38 pm ---Simple: Because even 6000 counts is 0.016% accuracy. Supporting 6000 counts properly already requires very high precision components.

--- End quote ---

Usually not, it can be as bad as 0.16%

Fungus:

--- Quote from: HKJ on October 28, 2020, 06:27:16 pm ---
--- Quote from: Fungus on October 28, 2020, 06:20:38 pm ---Simple: Because even 6000 counts is 0.016% accuracy. Supporting 6000 counts properly already requires very high precision components.

--- End quote ---

Usually not, it can be as bad as 0.16%

--- End quote ---

Sure, it drops down to 600 counts if you're measuring (eg.) 7V, that's 0.16%.

The solution isn't to go to 500k counts though. 10k counts would be 0.01% on all ranges.

If we apply Benford's law the ideal number of counts is 20k.

https://en.wikipedia.org/wiki/Benford%27s_law

2N3055:

--- Quote from: Fungus on October 28, 2020, 07:25:56 pm ---
--- Quote from: HKJ on October 28, 2020, 06:27:16 pm ---
--- Quote from: Fungus on October 28, 2020, 06:20:38 pm ---Simple: Because even 6000 counts is 0.016% accuracy. Supporting 6000 counts properly already requires very high precision components.

--- End quote ---

Usually not, it can be as bad as 0.16%

--- End quote ---

Sure, it drops down to 600 counts if you're measuring (eg.) 7V, that's 0.16%.

The solution isn't to go to 500k counts though. 10k counts would be 0.01% on all ranges.

If we apply Benford's law the ideal number of counts is 20k.

https://en.wikipedia.org/wiki/Benford%27s_law

--- End quote ---

Benford's law is not so much relevant in electronics in this context. We have common voltages used: 5, 12, 13.2, 24, 48, 120, 240, 440 etc...
You measure according to system voltages, and those will have standardized, artificial grouping.

20000 is very good but 50000/60000 count is even better and keeps electronics measurements in long scale most of the time.

That is my observation.. Not a law.

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