Methods for Low Power Temperature Control

摘要

The methods and devices by which the temperature of a single quartz crystal blank can be maintained at a constant operating temperature in extreme environmental conditions have been investigated. Four types of ovens, in which temperatures are controlled by a snap-action thermostat, were studied: (1) a 500-milliwatt oven (Type E6) requiring accessibility to the crystal and operating at +75C =2.5C over a -40C to +60C ambient; (2) a 50-milliwatt sealed oven (Type F6G) with similar operating requirements; (3) a less costly, 100-milliwatt sealed oven (Type G6G) with similar operating requirements; and (4) a 250-milliwatt oven (Type H6) requiring accessibility to a temperature-compensated crystal and operating at 0C=3C over an ambient range from-55C to 0C. Five ovens of each type were constructed and successfully tested. The amplitude of the crystal operating temperature oscillation, power consumption and warm-up time are within the required limits for the type E6, G6G and H6 ovens. Power consumption of the type F6G ovens is 50% higher than specified. (Author)