SU640142A1 - Temperature-measuring device - Google Patents

Description

(54) DEVICE FOR TEMPERATURE MEASUREMENT FIG. Figure 2 shows the volt-ampere characteristic of a two-pole device formed by two field-effect transistors, where / n and and „are the coordinates of the switch point. The device works as follows. Thyristor 1, capacitor 4, anode load 2 and power supply 3 are the usual relaxation autogenerator, the generation frequency of which is determined by the charging circuit: load 2, capacitor 4, voltage of power supply source 3 and switching voltage of thyristor 1. For autogeneration it is necessary , so that the load line 2 crosses the current-voltage characteristic of the thyristor / on the section with negative differential resistance. The Bipolar transistor 5 in the switch on used performs the function of a controlled Zener diode with a stabilization voltage determined by the voltage at its base, i.e. on the capacitor plates 4. Resistor 6 is used as a limiting resistance as in a conventional parametric voltage regulator. The connection of the field-effect transistors 9, 10 allows to obtain the current-voltage characteristic and shown in FIG. 2. Together with the temperature-sensitive element (thermistor) 7, the transistors 9, 10 form a temperature-sensitive voltage divider, the signal from the output of which is fed to the gate of the transistor 8. With constant parameters of the auto-oscillator circuit, the voltage U applied to the input of the temperature-sensitive voltage divider has a constant amplitude value. If the resistance value of the thermistor Rt is less than that determined by the expression: where / "and f / n are the coordinates of the switching point (Fig. 2), then the voltage drop across the transistors 9, 10 is determined by the PieHieM voltage on the plot oa (Fig. 2). If this condition is not fulfilled, then the voltage drop across the transistors 9, 10 is determined by the value of the Uny voltage (Fig. 2). The stabilization voltage of the Zener diode 12 is chosen approximately equal to the voltage t / n- At the moment of switching (point a in Fig. 2), the voltage across the transistors 9, 10 abruptly increases from U "to f / ,, p defined by point b after switching. At the switching edge (point a), the voltage at the gate of the transistor 8 is near zero, which ensures its open state. In this case, the signal of the minimum value is removed from its drain. After switching, the voltage drop across the transistors 9, 10 increases dramatically, and since the voltage f / np is much higher than the cutoff voltage of transistor 8, the latter is locked and a high level signal is removed from its drain equal to the voltage of the additional source 11. The first additional resistor 13 serves as the drain load of the transistor 5 and is used to pick up the output signal; the second additional resistor 14 is provided to limit the current of the Zener diode 12. Switching from point a to point b and reversible by changing the co-resistance of thermistor 7. When this resistance decreases to the level at which condition (1) breaks, switching occurs and periodic square-wave pulses appear at the output with a frequency determined by the oscillator generation frequency on the I, 2, 4 elements. With increasing resistance, when condition (1) becomes again true, transistor 5 goes into a static state and the output pulses stop. Consequently, the proposed thermoconverter due to the introduction of new elements and new connections between them, as well as due to the special inclusion of the bipolar transistor, is characterized by a positive effect, which consists in increasing the measurement accuracy and improving the stability of obtaining the relay impeller transfer characteristic as a function of the temperature of the controlled medium while simultaneously obtaining pulses at the output of the circuit. Formula of the invention A temperature measuring device comprising a thyristor with an anode load, a capacitor connected between the anode and the cathode of the thyristor, a temperature-sensitive element, a resistor, a power source, a bipolar transistor, characterized in that, in order to improve the measurement accuracy, two resistor, power supply, zener diode, three field-effect transistors, two. of which the sources are shorted, and the gate of each of them is connected to the drain of the other, and the drain of the p-type field-effect transistor is connected to the negative terminal of the power source, and the drain of the field-effect transistor with the n-type channel is connected to the gate of the third field-effect transistor with the p channel -type and through a temperature-sensitive element to the emitter of a bipolar transistor, the base of which is connected to the thyristor anode, and to a resistor connected by an anti-reverse terminal to the positive terminal of the main power source, and the source of the third additional field The second transistor is connected to the positive terminal of the additional power source and to the Zener diode cathode, its drain to the device output and also through the first additional resistor to the negative terminal of the additional power source and to the second additional resistor, the other output of which is connected to the Zener diode anode and negative terminal of the main power source.

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Sources of information taken into account in the examination:

1. Bilik R.V. et al. Pulsed circuits on dynistor and thyristor. M., “Science, 1970, p. 38

2. Copyright certificate

USSR № 190246, cl. G 01 K 7/16, 1967.

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