Abstract: Method and apparatus for calibrating a temperature measuring device by operating a heat source at a preset temperature as determined by a temperature sensing resistor and a digitally calculated temperature which varies nonlinearly with the resistance of the resistor, and obtaining the coefficients for the calculation by operating the device at a preset temperature and comparing this temperature with that of a standard temperature measuring device.

Abstract: A system for calibration of a temperature probe at temperatures both above and below ambient. A dry type heatsink for receiving the temperature probe, with a plurality of thermo-electric modules for selectively heating and cooling the heatsink to a preset temperature. A control circuit with a bridge arm for the desired or set temperature and a bridge arm for the actual or sensed temperature, providing inputs to a comparator for determining deviation from the set temperature and energizing the modules to change the temperature at the heatsink. A display unit for selectively displaying the actual temperature and the set temperature and for use in calibrating the system. A constant current source for the sensing arm of the bridge for improving the accuracy of the sensed temperature.

Abstract: A temperature calibration system including a well for receiving a temperature sensor such as a thermometer or thermocouple, and a heater for heating the well to a desired and adjustable temperature. A single well instrument providing a temperature range of 100.degree. to 1199 .degree. F in one degree steps. A control circuit for controlling well temperature to a few tenths of a degree and including means for manually setting the desired temperature, a bridge incorporating the temperature sensor and the temperature setting resistances, amplifiers for switching power to the well heater, and a null meter for indicating when the instrument is operating at the desired temperature.