jgray at zianet.com
Wed Mar 9 01:54:51 EST 2016
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
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
> 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
> 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.
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