[volt-nuts] 10VDC

[Marv Gozum]

There is also, discussed here, a survey of available references from 
1960-1980s favored 10V at least in the mind of the folks at NIST:

https://www.gpo.gov/fdsys/pkg/GOVPUB-C13-2c2d0649085cc34834a8f42deaad328e/pdf/GOVPUB-C13-2c2d0649085cc34834a8f42deaad328e.pdf

So even if not true by the 1980s, the data generated by then aged, and 
well characterized 10V references established the 10V 73x Fluke style 
reference as a defacto standard.  Tie that to Dr Frank's description of 
the evolution of instruments and practical issues of designing around 
'decades' gelled 10V into what is today.


On 3/9/2016 1:54 AM, Joseph Gray wrote:
> Frank,
>
> Thanks for the info. Do you have a link to the EEVblog discusison on
> this? If not, possibly some search terms to narrow it down (10VDC is
> too generic).
>
> Joe Gray
> W5JG
>
>
> On Tue, Mar 8, 2016 at 4:47 PM, Frank Stellmach
> <frank.stellmach at freenet.de> wrote:
>> Hi Joe,
>>
>> yes, there has been a longer discussion on eevblog a few years ago..
>> interesting explanations..
>>
>>
>> Here's mine:
>>
>> Originally, the Weston Standard Cells had an odd value of 1.01865V. This was
>> transferred to other values by KV dividers. These dividers were easily built
>> in decades, but maybe that did not prefer 10V, yet.
>>
>> Analog meters at that time also had no preference, as they had several
>> overlapping ranges, sequenced like 1-3-10, or 1-2-5-10.
>>
>> When more precise DVMs with higher resolution were built in the 1960ties,
>> like the Fluke Differential DVMs, as for example the 883A, 893A, and so on,
>> they got decimal ranges, as a necessity for cascading.
>> HP also designed several standards and differential DVMs having 9.9999X as
>> F.S.
>>
>> Also, digital counters and early digital DVM, being based on such counters,
>> naturally had a F.S. like 9.999.
>>
>> You can often find in the catalogues of that era, that digital or
>> differential DVM with a F.S. of 11V or 12V were described as 10V instruments
>> with 10% or 20% of Overrange Capability, or so.
>>
>> So there was a necessity to have as a reference these Cardinal Points like
>> 100mV, 1V, 10V, 100V, 1kV, with 10V being the most stable and easiest one to
>> realize.
>>
>> And that lasts until today, although a direct calibration on the 6.9.. 7.2V
>> of zener elements like the LTZ1000 or LTFLU would be much more stable and
>> more precise than the 10V from a 732B.
>>
>> Frank
>>
>>
>>
>>
>>
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-- 

Best Wishes,



Marv