[volt-nuts] Traveling Standards

[Andreas Jahn]

 Hello Bob,

> LM7815 TC =~ 1 mV/C => 0.125 uA/C => 0.018 ppm/C.
> LM7815 line regulation =~ 13 mV/V.
>   For 35V +/- 10% => 46 mV => 5.7 uA => 0.813 ppm.

I would not heat too much by the voltage regulator.
Or do good thermal isolation.
The covar pins of the hermetic packages have
40uV/K against copper. And Im not shure on my
LTZ1000 if different heating of the LT1763 has
influence. (Distance is only about 1 Inch in the current design).


> Rs TC =~ 100 ppm/C => dIs/dT =~ 100 ppm/C => 0.1 uA/C => 0.014 ppm/C.
> Rs stability =~ .5% / 1000 hrs => 5.0 uA => 0.714 ppm.
> 
> Comments - feedback?

In this case I would use a more stable resistor.
A precision wirewound (NEOHM UPW50 or Riedon USR2) of 10k 
in parallel with a 41K2 15ppm 0.1% Metal film (RC55Y).

With best regards 

Andreas