SU645040A1 - Temperature-measuring device - Google Patents

Description

one

The invention relates to the field of thermometry.

A device for measuring temperature is known, which contains a two-transistor multivibrator with a collector-base connection, the discharge circuits of which include temperature-sensitive resistors, and a power source 1.

However, the known device has a low thermal stability.

The closest to the technical essence of the invention is a device for measuring temperature, containing a two-transistor multivibrator with a collector-base link, two capacitors, two electrical values, which consist of a capacitor and a transistor connected in series with it, two thermistors included in a discharge circuit, two resistors of the collector load of the transistors of the multivibrator, which are also connected to the emitters of two compensating transistors, and a power source.

However, in the known device, the full thermal stabilization by the norm of unlocking the transistors of the multivibrator and their amplification factor is not carried out, which leads to a decrease in the measurement accuracy.

The purpose of the invention is to improve the measurement accuracy.

For this purpose, two groups of transistors, each of which consists of at least three transistors, and two groups of correction resistors, but consisting of at least three resistors, are added to the device, with the collectors of each transistor of the multivibrator through the emitter-base transitions of the first pair of additional transistors with a free collector connected to one capacitor plate, to the terminals of the resistor of the collector load and to the emitters of the second pair of additional transistors, the base, which through n The first pair of correction resistors is connected to the negative terminal of the power supply, and the collectors of these transistors are connected to the emitters of the compensating transistors and to the second terminals of the resistor of the collector load and through the second pair of correction resistors to the positive terminal of the power source. The bases of the compensating transistors are connected to the emitters of the third pair of additional transistors with free collectors and, through the third pair of correction resistors, are connected to the positive terminal of the power source, to the negative terminal of which the bases of the third pair of additional transistors are connected.

The drawing shows the electrical circuit of the device.

The device contains transistors 1 and 2 multivibrator, capacitors 3 and 4, thermistors 5 and 6, resistors 7 and 8 of the collector load, capacitors 9 and 10, transistors 11 and 12, connected 1, transistors 13 and 14, first pair 15, 16 additional transistors, the second pair 17, 18 additional transistors, the first pair of additional correction resistors 19, 20, the power source 21, the second pair 22, 23 correction resistors, the third pair 24, 25 additional transistors, the third pair 26, 27 additional correction resistors.

The device works as follows.

The period following the generated pulses

G Svds.p.

B - i / o - Oo

where E is the supply voltage of the circuit;

t / o - unlocking the transistor with a free collector and a collector voltage of 0;

t / o - unlocking the key transistor at a collector voltage equal to;

t / o is the voltage drop across transistors with a free collector in the presence of correction resistors;

R is the resistance of the base resistors 5.6;

C - capacitor capacitance 3.4. Taking into account what can usually be considered and what can be obtained with the help of correction resistors, the value UQ Uo, the latter equality takes the form

 , 4RC, E - 3f / o

which proves that it can be ensured that the thermal stability of the circuit for unlocking the key transistors 1, 2 is almost complete.

Introduction to the transistors 15, 17, 16, 18 n resistors 19, 20 allows the circuit to stabilize and increase the gain of transistors 1. The presence of transistors 1, 17 and 2, 18 of the same structure, where transistors 17, 18 are nonlinear collector load key transistors 1, 2, prn discharge of capacitors 3,4,

almost guarantees the same gain and temperature properties (especially if the transistors are selected from the same batch). This, in turn, ensures the constant saturation coefficient of the transistors of the multiplier when the ambient temperature fluctuates. The constancy of saturation coefficients at dark substrate variations increases the thermal stability of the circuit. Resistors 19, 20 allow you to set the desired value of the collector current of the transistors 17, 18. To disconnect the transistors 17, 18 from the circuit at the time of charging

capacitors 3, 4 are introduced transistors 15, 16 with a free collector.

Improving measurement accuracy improves the quality of operation of temperature monitoring and measurement systems in various engineering areas.

Claims (2)

Invention Formula A device for measuring temperature, containing a two-transistor multivibrator with collector-base connections, two capacitors, two electrical circuits, each of which consists of a condiser and a transistor connected to it consequently, two thermistors connected into the discharge circuit, two resistors of the collector load of the transistors of the multivibrator, which are also connected to the emitters of the two compensating transistors, and the power source, different In order to increase measurement accuracy, two groups of transistors, each consisting of at least three transistors, and two groups of correcting resistors, consisting of at least three resistors, and the collectors of each transistor of the multivibrator through emitter-base transitions of the first pair of additional transistors with a free the collector is connected to one capacitor plate, to the terminals of the collector load resistors and to the emitters. The second pair of additional transistors, the bases of which through the first pair of correction resistors are connected to the negative terminal of the power supply, and the collectors of these transistors are connected to the emitters of the compensating transistors and to the second terminals of the resistors collector load. and through the second pair of correction resistors to the positive terminal of the power source, and the bases of the compensating transistors are connected to the emitter of the third bunker of additional transistors with free collectors and through the third pair of correction resistors are connected to the positive terminal of the power source, to the negative terminal of which the bases of the third pair of additional transistors are connected. Sources of information taken into account in the examination 1. V. P. Budnov, Relaxation generators - impulse converters ne electrical quantities. M., “Energie, 1974, p. 83 2. USSR author's certificate No. 581390, cl. G 01 K 7/16, 1976.