Abstract
An automatic system has been built for recording outputs from sensitive thermocouple psychrometers. The system comprises a scanner, amplifier, peak voltmeter and a multipoint potentiometric recorder. The inexpensive scanner and peak voltmeter, which are built from commercial components, and the psychrometers are described in detail. The system has a stability of ±0.01 μV, while the standard deviations for recorded outputs from two different types of psychrometer are ±0.03 μV and ±0.05 μV. The high quality of the instrument switch, which forms part of the scanner, suggests that the scanner might prove useful for other applications involving either d.c. or a.c. signals.