Abstract: An electronic thermometer comprises a temperature sensitive resistance element to be placed in contact with the area of which the temperature is to be measured. A first relaxation oscillator to which the resistance element belongs, provides a frequency depending on the temperature to be measured. A reference oscillator provides a reference frequency. The first frequency is counted in a counter during a period provided from the reference frequency by a divider. If a temperature or power supply drift affects the reference frequency, the same drift affects in the same direction the counted frequency, so that during the counting the effect of the drift is substantially cancelled. A memory and a comparator record the result of the counting only if it is higher than the preceding result, so that the thermometer operates as a maximum thermometer. The recorded result is provided to a decoder which controls a display device.

Abstract: The present invention is intended to solve the problem of the reliable acquisition of accurate temperature data for a miniature calculator provided for the application of family planning methods. The calculator is provided with a receptacle removably carrying a thermometric probe for providing the temperature measurement in a digital form. The circuits of the probe comprise an oscillator including a temperature responsive resistance element to be placed in contact with the area of the temperature to be measured, Tx. The output frequency fx of this oscillator is a function of Tx, and is measured by a counter controlled by a signal formed from a reference frequency fr provided by a reference oscillator and further provided to a frequency divider. A comparator compares the contents of the counter to that of a memory, and in case the counter contents is higher than the stored contents, the comparator controls the entry thereof to the memory so that the probe operates as a maximum thermometer.