[volt-nuts] Short term "standard" cell?

[David]

How do silver oxide cells compare to mercury cells for voltage
stability?  When I last looked into this, I concluded that there were
two different silver oxide chemistries with a slight variation in
voltage between them.

On Sat, 11 Mar 2017 09:21:02 -0800, you wrote:

>Hi Chris:
>
>I think it was my Heathkit VTVM that said to get a fresh AA battery and use it as a 1.52 Volt standard to calibrate the 
>meter. An even better way was to use a Mercury coin cell since they were 1.35 volts and very stable.  They were used for 
>light meters and voltage references because of the very flat discharge curve.
>
>But when you are looking for many more digits of accuracy/precision then a battery may not be the best choice since 
>pretty much everything will cause a variation.   Maybe in order of importance: temperature, atmospheric pressure, 
>humidity, impedance of measuring equipment, &Etc.
>
>There are a few low cost voltage standards available where the maker has an HP 3458.  For example by Geller and Malone:
>http://www.prc68.com/I/MTE.shtml#DCVR
>
>The care and feeding of chemical standard cells is such a pain and they are inferior to the modern electronic standards 
>so they have become obsolete.  The label on my Eppley shows 5 digits (4 printed and the last hand written).  Note since 
>there's liquid involved there is also an "Up" direction.
>http://www.prc68.com/I/Eppley.html#Standard_Cell
>
>http://www.prc68.com/I/Fluke332B.html