Dew-point Hygrometer with Constant Resistance Humidity Transducer
Curtis B. Campbell, Ben Leo Grover, Melvin D. Campbell · Journal of applied meteorology · 1971
A dew-point hygrometer with a constant resistance humidity transducer is described which uses the salt solution phase transition of lithium chloride as its basis of operation. The hygrometer employs electronic error detection and signal amplification to control the heat applied to the humidity transducer and to keep its resistance at the preselected value. Using this method a high accuracy of measurement can be achieved. Sufficient transducer area is exposed to the ambient environment to assure operation at the lithium chloride salt solution phase transition. This also minimizes error from contamination. The feature characteristics of this unit are: 1) low power requirements, 2) operation of the humidity transducer at a nearly constant pre-selected LiCl film resistance, 3) small transducer size suitable for micro-climate study, 4) balanced operation between transducer and electronics, and 5) interchangeability of humidity transducer units.