By intercepting on a selenium cell part of the light beam from the galvanometer in the bridge circuit of the resistance thermometer used to measure bath temperature, a signal is obtained which is used to trigger a photo‐relay via a secondary galvanometer. The photo‐relay controls the heating current in the thermostat. Design of the selenium cell mounting and accompanying circuits are described. The device holds a 50‐gal thermostat to 25° within a hunting amplitude of 0.002°C.
REFERENCES
1.
2.
R. B.
Scott
and F. G.
Brickwedde
, J. Research Natl. Bur. Standards
6
, 401
(1931
).3.
J. C.
Southard
and D. H.
Andrews
, J. Franklin Inst.
207
, 323
(1929
).4.
5.
6.
7.
8.
9.
This content is only available via PDF.
© 1959 The American Institute of Physics.
1959
The American Institute of Physics
You do not currently have access to this content.
