[Boatanchors] Weston Cell

[Pete Williams]

​...Probably already been  established  but  Henney, Radio Engineering
Handbook  fifth edition, states inter  alia
''standard of voltage is  maintained  by the   N B S as the average of a
number of  Weston  SATURATED cadmium cells  known  as the  'Weston Standard
Cell'. The  average value of this bank is 1.018636 absolute  volts  at  20
C .
The  unsaturated  cadmium cell must be  compared with the  saturated  for
initial  calibration. Its  voltage is  constant to better than  1 part in
10,000., but cells  must be must be  certified  yearly as potential tends
to drop very  approximately
50uV  per  year.
They  must always be used in null fashion with no more than 50uA  drawn
from the  cell  at  any time .'

Cheers Pete  VK3IZ'