SU979894A1 - Time-pulse temperature meter (its versions) - Google Patents

Description

(54) TIME IMPULSE TEMPERATURE METER (ITS OPTIONS)

one

The invention relates to the field of temperature measurements, namely, devices for measuring temperature, in which the measured parameter — temperature is converted into a pulse signal of a certain duration.

The time is known for a pulse temperature meter containing a resistance thermocouple with a limiting resistor, connected to a constant voltage source and a differential amplifier, the output of which is connected to a comparison circuit, an exponential voltage generator, and a clock pulse generator C1.

The disadvantage of this device is its complexity ..

The closest to the technical essence of the invention is the time A named pulse temperature meter containing a constant voltage source connected to a voltage divider resistors, the midpoint of which is connected to the first input of the comparison circuit.

the second input of which is connected to the capacitor, the key and the first output of the thermal converter of the resistance, and the output is connected to the second switch 1, a pulse generator connected to the control keys switch. In order to simplify the device, the keys in it are made on C 2 field-effect transistors.

The drawback of the device is the presence of an error arising in the measurement of temperatures at which the resistance of the thermal converter decreases to values commensurate with the resistance of the open key at the field-effect transistor. Due to this, the capacitor discharge does not occur to zero, but to a voltage determined by the divider; thermal converter resistance - the resistance of the open channel of the transistor.

Claims (2)

An error also appears, due to the fact that with a decrease in the resistance of the thermal converter, the current in the thermal converter increases, and consequently, the power dissipated on it, which at 3979 leads to a self-heating thermal converter. The aim of the invention is to improve the accuracy of temperature measurement. The goal is achieved by the fact that at the time the pulse transducer of temperature was introduced a field-effect transistor, the drain of which is connected to the source of the NIL voltage, the source is connected to the second transducer of the resistive temperature transducer, and the gate is connected to the second input of the comparison circuit. In the event that the temperature meter has higher requirements in terms of measurement accuracy, a constructive implementation of a pulse meter time is preferred, in that a bipolar transistor is inserted in it, the collector of which is connected to. the voltage source, the emitter - with a BTO eye output of a thermal resistance transducer, and the base - with a second output of the pulse generator. FIG. 1 shows a diagram of the first embodiment of the time of the pulse meter} in FIG. 2 - scheme of the second option. The time pulse temperature meter contains a constant voltage source 1, a thermoprefector resistance 2, a capacitor 3, a voltage divider on resistors 4-5, a comparison circuit 6, a pulse generator 7, two switches 8 and 9 on field-effect transistors. The first option is the time of the pulse meter contains a field-effect transistor 10, the second option is a bipolar transistor 11, and the generator and has a second output from which pulses are taken, the polarity of which is opposite to the polarity of the pulses taken from the first output of the generator. The impulse temperature meter operates in the following way. The pulse generator forms a sequence of square pulses of positive polarity. Upon receipt of positive-polarity impulse switches on the gates of the transistors, the key 8 short-circuits the capacitor providing a discharge of the capacitor, and the key 9 short-circuits the output of the comparison circuit, removing the voltage from its output. When the zero voltage transistors arrive at the gates, the keys 8 and 9 close, the capacitor starts charging through the resistance transducer 2, and a signal appears at the output of the comparison circuit 4 When charging the capacitor before the voltage divider, the resistors 4 and 5 is happening - the operation of the comparison circuit 6, the signal at the output of the comparison circuit is lost. Since the charge rate of the capacitor depends on the resistance of the thermal converter, the duration of the pulse generated at the output of the reference circuit is proportional to the resistance of the thermal converter and therefore the temperature to be measured. The value of the threshold of the comparison circuit is chosen approximately by an order of magnitude less than the value of the voltage of the voltage source 1, therefore the voltage across the capacitor almost increases according to a linear law. The field effect transistor 10, connected according to the gok stabilizer circuit, multiplies the resistance of the thermal converter by a factor of 10-20, depending on the type of the transistor. This leads to a decrease in the residual voltage on the key 8 During the discharge of the capacitor and, consequently, to a more complete discharge of the capacitor, as well as to a decrease in the current flowing through the thermocouple, i.e. to a decrease in the power dissipated on the thermal converter. In the meter according to the second embodiment, during the supply of a positive pulse to the gates of the transistors 8 and 9, i.e. during the discharge of the capacitor, a negative pulse from the second output of the pulse generator is applied to the base of the transistor 11, which performs the function of a switch. In this case, the transistor 11 disconnects the thermal converter from the voltage source, providing a more complete discharge of the capacitor and reducing the average power dissipated on the thermal converter. During the zero-voltage action, the gates of transistor 11 receive a positive impulse on the gates of transistors 8 and 9, opening transistor 11. The presence of new elements and new connections between elements distinguishes the proposed time from a pulsed temperature meter from the known one, as they significantly improve the accuracy of temperature measurement with a slight complication meter. Claims 1. A temporal temperature measuring instrument containing a constant voltage source connected to a voltage divider across resistors, is average the point of which is connected to the first echo of the comparison circuit, the second input of which is connected to the capacitor, key I, the first output of the resistance thermocouple, and the output connected to the second key, a pulse generator connected to the control inputs of the keys, in order to improve the accuracy measurement, a field-effect transistor, whose stack is connected to a voltage source, is introduced into it, the source is connected to the second output of the thermal transducer, and forms a resistor, and the gate with the second input of the comparison circuit. 2. Time pulse temperature meter containing a constant voltage source connected to the voltage divider on the resistors, the midpoint of which is connected to the first input of the comparison circuit, the second input of which is connected to the capacitor, the key and the first the output of the thermal converter, and the output is connected to the second key, a pulse generator; connected to the control inputs of the keys, characterized in that, in order to improve the measurement accuracy, a bipolar transistor is inserted in it, the collector of which is connected to the voltage source, the emitter is connected to the second output of the resistance thermocoupler, and the base is connected to the high output of the pulse generator. Sources of information taken into account in the examination 1.Vorius V. Im Monastyrsky V. Ya., Tchaikovsky DI. Digital Time Iltulse Temperature Meter.-Devices and control systems. 1978, p. 21-22. 2. USSR author's certificate for application number 2957O88 / 18-1Q, .kl.e 01 K 7/18, 1980 (prototype). 1