SU1682825A1 - Digital thermometer - Google Patents

Abstract

The invention relates to the field of temperature measurements. The purpose of the invention is to increase the metrological accuracy of measurements. The execution of sources 3 and 6 of the voltages forming the phase measuring circuit, in the form of alternating sinusoidal voltage sources, the phase shift between which is not equal to 180 °, the introduction of three comparators 7-9, two elements AND 10 and 11 and the phase shift conversion, proportional to temperature, digitized with indication on block 15 using a pulse counter 14, allows to improve the metrological accuracy of measurements due to the fact that in the proposed device information about the temperature carries the phase of the total signal (WzO vector, § 31 or BC2), measured relative to the phase of another sum signal (vector A), while phase shifts caused by instability of sources 3 and 6. are mutually compensated and do not affect the measurement result, which increases its accuracy. 3 il.

Description

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Claims (1)

Claim A digital thermometer comprising a first voltage source, a thermistor and a first reference resistor, a second and third reference resistors connected in series, and an indication unit, the first terminals of the first voltage source, a thermistor and a second reference resistor connected to a common bus, characterized in that . in order to improve the metrological accuracy of measurements, a second voltage source is inserted into it, connected between the common bus and the second output of the third reference resistor, three comparators, two I elements, a pulse generator, a decoder and a pulse counter, while the first and second inputs of the first comparator are connected respectively to the common points of the first voltage source and the first reference resistor, the second voltage source and the third reference resistor, and the output of the first comparator is connected to the first inputs of the first and of the other elements And, the second inputs of which are connected to the output of the second comparator, the first and second inputs of which are connected respectively to the common point of the thermistor and the first reference resistor and to the common point of the second and third reference resistors, the third comparator, which is connected by inputs to the second voltage source and the output connected to the third input of the first element And and the input of the decoder, the second output of which is connected to the third input of the second element And, the fourth input connected to the output of the generator and pulses, and the output to the counting input of the pulse counter, the zeroing input which is connected to the first output of the decoder, the output of the first element And and the output of the pulse counter are connected to the inputs of the display unit, while the first and second voltage sources are made in 5 form of a sinusoidal voltage source, phase shift between which is not equal to 180 °. Fig.Z