Abstract: In order to permit in a simple manner the use of a digital processing unit in a regulating system for an air conditioning or heating plant, each temperature sensor of a temperature-measuring device is connected to a capacitor so as to charge it with a current proportional to the measured temperature. The capacitor is connected to one input of a comparator, and a reference voltage is applied to the other input. The output of the comparator is applied to an input of a digital processing unit which, at the start of the temperature measurement, will discharge the capacitor over a predetermined period and will then, at uniform time intervals, check the output signal supplied by the comparator for change. The number of samplings from the end of capacitor discharge until the time a change in the comparator output occurs is available as a digital value corresponding to the measured temperature.

Abstract: An apparatus for measuring fluid flow velocity includes an oscillation generator triggered by a circuit driver and a receiver which are disposed in oblique, opposed relation with respect to the direction of flow of the fluid, and an analyzing circuit for the determination of the transit time of the oscillations through the fluid, which analyzing circuit is made up by an exclusive OR-circuit connected on the input side of the receiver and to the oscillation generator operating with constant frequency and constructed as a square-wave impulse generator, a low-pass filter following it, and circuit means for detecting the differential value between a reference voltage and the voltage at the low-pass filter. The apparatus measures the phase-shift between the emitted and received signals, as a result of which a high accuracy is achieved even in case of short measuring distances and the apparatus can be constructed at very low costs.