CN215865540U - Thermocouple cold junction compensation circuit and thermocouple temperature measurement system - Google Patents
Thermocouple cold junction compensation circuit and thermocouple temperature measurement system Download PDFInfo
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- CN215865540U CN215865540U CN202122046416.5U CN202122046416U CN215865540U CN 215865540 U CN215865540 U CN 215865540U CN 202122046416 U CN202122046416 U CN 202122046416U CN 215865540 U CN215865540 U CN 215865540U
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Abstract
The utility model discloses a thermocouple cold end compensation circuit, which comprises a differential operational amplifier and a bridge type voltage division circuit; the bridge-type voltage division circuit is connected with a power supply and a differential operational amplifier, and the output voltage of the differential operational amplifier is used as cold end compensation voltage of the thermocouple. One bridge arm in the bridge type voltage division circuit comprises a resistive device with the resistance value adjustable along with the temperature, and the other bridge arms comprise resistors with fixed resistance values; the resistive device with the resistance value adjustable along with the temperature and the cold end of the thermocouple are in the same temperature environment. By adopting the scheme, when the cold ends of the thermocouples are in different temperature environments, the resistance value of the resistive device is changed along with the temperature change, so that the compensation voltage of the compensation circuit is changed, the dynamic compensation of the cold ends is realized, and the waste of human resources is reduced. In addition, the utility model also discloses a thermocouple temperature measurement system which comprises a thermocouple cold end compensation circuit and has the same effect as the thermocouple cold end compensation circuit.
Description
Technical Field
The utility model relates to the technical field of electronic circuits, in particular to a thermocouple cold end compensation circuit and a thermocouple temperature measurement system.
Background
The thermocouple is a closed loop formed by two different conductor materials or semiconductor materials A and B, when two ends of the thermocouple are connected with each other, as long as the temperature at the connection point is different, wherein one end of the thermocouple is at T1 and is called as a working end or a hot end, and the other end of the thermocouple is at T0 and is called as a free end (also called as a reference end) or a cold end, an electromotive force is generated in the loop, and the direction and the magnitude of the electromotive force are only related to the material of the conductor and the temperature of the two connection points. This phenomenon is called "thermoelectric effect", while the circuit made up of two conductors or semiconductors called "hot electrodes" is called "thermocouple", and the electromotive force generated is called "thermoelectromotive force".
In the practical use process, the hot end is used as a testing end and placed in a heat source, and the cold end is usually placed in room temperature, so that the cold end of the thermocouple can be normally used only by corresponding compensation due to the fact that the room temperature generally has a certain difference under the influence of the use environment and the region.
A common compensation method is a circuit compensation method, which provides a rated voltage for a cold end of a thermocouple for compensation, and needs to adjust a compensation value of the voltage in different temperature environments, at this time, manual intervention is needed, and an operator increases or decreases a resistance according to the temperature to change the compensation voltage for compensation, thereby wasting human resources.
Therefore, how to reduce the waste of human resources when performing cold junction compensation on the thermocouple in different temperature environments is an urgent problem to be solved by those skilled in the art.
SUMMERY OF THE UTILITY MODEL
The utility model aims to provide a thermocouple cold end compensation circuit and a thermocouple temperature measurement system, which are used for reducing the waste of human resources when cold end compensation is carried out on a thermocouple in different temperature environments.
In order to solve the above technical problem, the present invention provides a cold end compensation circuit for a thermocouple, comprising:
a differential operational amplifier and a bridge voltage divider circuit;
one bridge arm in the bridge type voltage division circuit comprises a resistive device with the resistance value adjustable along with the temperature, and the other bridge arms comprise resistors with fixed resistance values; the resistance device with the resistance value adjustable along with the temperature and the cold end of the thermocouple are in the same temperature environment;
the first end of the bridge-type voltage division circuit is connected with a power supply, the second end of the bridge-type voltage division circuit is connected with the non-inverting input end of the differential operational amplifier, the third end of the bridge-type voltage division circuit is connected with the inverting input end of the differential operational amplifier, and the fourth end of the bridge-type voltage division circuit is grounded;
and the output voltage of the differential operational amplifier is used as the cold end compensation voltage of the thermocouple.
Preferably, the resistive device with the resistance value adjustable along with the temperature is a platinum resistor;
the first end of the platinum resistor is used as the third end of the bridge-type voltage division circuit and connected with the inverting input end of the differential operational amplifier, and the second end of the platinum resistor is used as the fourth end of the bridge-type voltage division circuit and grounded.
Preferably, the resistive device with the resistance value adjustable with temperature includes:
the temperature sensor, the control chip, the switches and the resistors with corresponding quantity; wherein the resistances of the resistors are all different;
the temperature sensor is connected with the control chip, the control chip is connected with the plurality of switches, the switches are connected with the resistors in a one-to-one correspondence mode, and the control chip controls and selects the resistors with different resistance values to be connected into the bridge arm through temperature signals sent by the temperature sensor.
Preferably, the method further comprises the following steps:
a temperature display instrument;
the temperature display instrument is connected with the output end of the differential operational amplifier and the thermocouple.
Preferably, the method further comprises the following steps:
a second differential operational amplifier;
the non-inverting input end of the second differential operational amplifier is connected with the thermocouple, and the inverting input end of the second differential operational amplifier is connected with the output end of the differential operational amplifier.
Preferably, the fixed-resistance resistor includes:
a first resistor, a second resistor and a third resistor;
the first end of the first resistor and the first end of the third resistor are commonly used as the first end of the bridge voltage division circuit, the second end of the first resistor and the first end of the second resistor are commonly used as the second end of the bridge voltage division circuit, the second end of the third resistor and the first end of the platinum resistor are commonly used as the third end of the bridge voltage division circuit, and the second end of the second resistor and the second end of the platinum resistor are commonly used as the fourth end of the bridge voltage division circuit;
the resistance values of the first resistor and the third resistor are the same, and the resistance values of the second resistor and the platinum resistor are the same when the temperature environment is 0 ℃.
Preferably, the method further comprises the following steps:
a filter circuit;
the input end of the filter circuit is connected with the second differential operational amplifier, and the filter circuit is used for suppressing and preventing interference.
Preferably, the method further comprises the following steps:
an alarm device;
the alarm device is connected with the power supply and used for giving out a prompt when the power supply outputs or not.
Preferably, the alarm device includes:
an indicator light and a buzzer;
the indicator light and the buzzer are connected with the power supply and used for displaying whether the power supply outputs or not.
In order to solve the technical problem, the utility model also provides a thermocouple temperature measuring system which comprises the thermocouple cold end compensation circuit.
The utility model provides a thermocouple cold end compensation circuit, which comprises a differential operational amplifier and a bridge type voltage division circuit; the bridge-type voltage division circuit is connected with a power supply and a differential operational amplifier, and the output voltage of the differential operational amplifier is used as cold end compensation voltage of the thermocouple. One bridge arm in the bridge type voltage division circuit comprises a resistive device with the resistance value adjustable along with the temperature, and the other bridge arms comprise resistors with fixed resistance values; the resistive device with the resistance value adjustable along with the temperature and the cold end of the thermocouple are in the same temperature environment. By adopting the scheme, when the cold ends of the thermocouples are in different temperature environments, the resistance value of the resistive device is changed along with the temperature change, so that the compensation voltage of the compensation circuit is changed, the dynamic compensation of the cold ends is realized, and the waste of human resources is reduced.
In addition, the thermocouple temperature measuring system provided by the utility model comprises the thermocouple cold end compensation circuit, and the effect is the same as the above.
Drawings
In order to illustrate the embodiments of the present invention more clearly, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings can be obtained by those skilled in the art without inventive effort.
Fig. 1 is a circuit diagram of a cold end compensation circuit of a thermocouple according to an embodiment of the present invention;
fig. 2 is a circuit diagram of a thermocouple temperature measuring system according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without any creative work belong to the protection scope of the present invention.
The core of the utility model is to provide a thermocouple cold end compensation circuit and a thermocouple temperature measurement system, which are used for reducing the waste of human resources when cold end compensation is carried out on a thermocouple.
In order that those skilled in the art will better understand the disclosure, the utility model will be described in further detail with reference to the accompanying drawings and specific embodiments.
Fig. 1 is a circuit diagram of a thermocouple cold junction compensation circuit according to an embodiment of the present invention, as shown in fig. 1, the circuit includes: a differential operational amplifier and a bridge voltage divider circuit. One bridge arm in the bridge type voltage division circuit comprises a resistive device with the resistance value adjustable along with the temperature, and the other bridge arms comprise resistors with fixed resistance values. The resistive device with the resistance value adjustable along with the temperature and the cold end of the thermocouple are in the same temperature environment. The first end of the bridge-type voltage division circuit is connected with the power supply, the second end of the bridge-type voltage division circuit is connected with the non-inverting input end of the differential operational amplifier, the third end of the bridge-type voltage division circuit is connected with the inverting input end of the differential operational amplifier, and the fourth end of the bridge-type voltage division circuit is grounded. The output voltage of the differential operational amplifier is used as the cold end compensation voltage of the thermocouple.
The thermocouple cold junction compensation circuit that this embodiment provided for reduce manpower resources's waste when carrying out cold junction compensation to the thermocouple in different temperature environment. When the cold end of the thermocouple is compensated, the voltage passes through the bridge-type voltage division circuit and the operational amplifier to become compensation voltage, and the cold end compensation of the thermocouple is realized. When the cold ends of the thermocouples are located in different temperature environments, the generated electric potential can change, and the resistance value of the resistive device with the same temperature environment as the cold ends of the thermocouples in the bridge-type voltage division circuit also changes along with the resistance value of the temperature-adjustable resistive device, so that the compensation voltage changes, and the compensation of the cold ends of the thermocouples is met.
The resistive device with the resistance value adjustable along with the temperature can be a temperature-sensitive resistor, such as R7 in FIG. 1, or can be a form of combining a temperature sensor with resistors with different resistance values. For the latter, the temperature sensor is used to obtain the current ambient temperature to determine the resistance value to be input, and then the control chip connects the resistance corresponding to the resistance value to the corresponding bridge arm, which may be an independent individual or a combination of different types or the same type of devices, and is not limited herein. The number of resistors of fixed resistance on the other bridge walls is likewise not limited.
In the prior art, since the electromotive force generated by the thermocouple is small, it is usually required to be amplified by a differential operational amplifier in use, as shown in U3 in fig. 2, and the differential operational amplifier U1 in the present circuit further adjusts the voltage output by the bridge voltage dividing circuit to be a compensation voltage. The adjustment may be voltage following or voltage amplification, and the specific adjustment is determined by the amplification factor of U3. It is understood that, when the amplification factor of the differential operational amplifier for amplifying the electromotive force generated by the thermocouple is determined, the amplification factor of the differential operational amplifier U1 in the present circuit and the power supply voltage are determined by calculation. The present embodiment provides a differential operational amplifier, which is AD623ARZ, and the voltage amplification factor formula thereof is as follows:
wherein, VCDifference of input voltage, V, for AD623ARZOFor the amplified output voltage, RGThe resistance values of the series resistors of the differential operational amplifier are shown as R8, R9 and R10 in FIG. 2. In the use process of the thermocouple, the temperature environment of the cold end of the thermocouple is possibly above zero degrees centigrade or below zero degrees centigrade, and the positive and negative of the compensation voltage required under different conditions are different, so that the differential operational amplifier in the circuit supports dual power supply, so that the differential operational amplifier can amplify a positive voltage input signal and a negative voltage input signal. The output voltage of the differential operational amplifier is the compensation voltage required by the thermocouple, and the output voltage and the electromotive force generated by the thermocouple can be connected to other devices, such as an instrument, together to realize cold end compensation of the thermocouple.
The thermocouple cold end compensation circuit provided by the embodiment of the utility model comprises a differential operational amplifier and a bridge type voltage division circuit; the bridge-type voltage division circuit is connected with a power supply and a differential operational amplifier, and the output voltage of the differential operational amplifier is used as cold end compensation voltage of the thermocouple. One bridge arm in the bridge type voltage division circuit comprises a resistive device with the resistance value adjustable along with the temperature, and the other bridge arms comprise resistors with fixed resistance values; the resistive device with the resistance value adjustable along with the temperature and the cold end of the thermocouple are in the same temperature environment. By adopting the scheme, when the cold ends of the thermocouples are in different temperature environments, the resistance value of the resistive device is changed along with the temperature change, so that the compensation voltage of the compensation circuit is changed, the dynamic compensation of the cold ends is realized, and the waste of human resources is reduced.
On the basis of the above embodiments, in this embodiment, the resistive device with a resistance value adjustable with temperature is a platinum resistor.
The first end of the platinum resistor is used as the third end of the bridge-type voltage division circuit and is connected with the inverting input end of the differential operational amplifier, and the second end of the platinum resistor is used as the fourth end of the bridge-type voltage division circuit and is grounded.
According to the cold end compensation circuit of the thermocouple, the resistive device with the resistance value adjustable along with the temperature is selected as the platinum resistor, the resistance value of the platinum resistor increases along with the increase of the temperature and decreases along with the decrease of the temperature, and the resistance value change is in a linear relation with the temperature. It can be understood that the use of platinum resistors makes the circuit simpler than the choice of a temperature sensor in combination with resistors, and at the same time, provides more accurate compensation voltage due to the linear relationship between the resistance change and temperature.
On the basis of the foregoing embodiment, in this embodiment, a resistive device whose resistance is adjustable with temperature includes: the temperature sensor, the control chip, the switches and the resistors with corresponding quantity; wherein the resistances of the resistors are all different;
the temperature sensor is connected with the control chip, the control chip is connected with the plurality of switches, the switches are connected with the resistors in a one-to-one correspondence mode, and the control chip controls and selects the resistors with different resistance values to be connected into the bridge arm through temperature signals sent by the temperature sensor.
Taking the number of the switches and the resistors as 3 as an example, the switches are respectively a first switch, a second switch, a third switch, and the resistors are respectively a fourth resistor, a fifth resistor, and a sixth resistor. The temperature sensor is connected with the first end of the control chip, the second end of the control chip is used as the third end of the bridge voltage division circuit and is connected with the inverting input end of the differential operational amplifier, the third end of the control chip is connected with the first end of the first switch, the first end of the second switch and the first end of the third switch, the second end of the first switch is connected with the first end of the fourth resistor, the second end of the second switch is connected with the first end of the fifth resistor, the second end of the third switch is connected with the first end of the sixth resistor, and the second end of the fourth resistor, the second end of the fifth resistor and the second end of the sixth resistor are used as the fourth end of the bridge voltage division circuit and are grounded.
According to the cold end compensation circuit of the thermocouple, provided by the embodiment of the utility model, the temperature sensor is used for receiving the temperature signal of the ambient temperature environment and transmitting the temperature signal to the control chip, and the control chip can control the switch according to the temperature signal and select resistors with different resistance values to be connected into the circuit so as to change the compensation voltage. It can be understood that the resistors in this embodiment are connected in series, so the fourth resistor, the fifth resistor, and the sixth resistor have different resistances. Of course, if the resistance of the circuit is only required to be reduced, the circuit can be connected in parallel, and the resistances of the resistors can be the same.
In a specific implementation, in order to actually use the thermocouple, a compensation voltage is also required to be added to the electromotive force generated by the thermocouple.
On the basis of the above embodiment, in this embodiment, the method further includes:
a temperature display instrument;
the temperature display instrument is connected with the output end of the differential operational amplifier and the thermocouple.
According to the thermocouple cold end compensation circuit provided by the embodiment of the utility model, the electromotive force and the compensation voltage generated by the thermocouple are combined through the temperature display instrument, so that the thermocouple cold end compensation is realized, meanwhile, the combined voltage is converted into the temperature and displayed on the dial plate, the temperature measured by the thermocouple can be obtained, and the practical use of the thermocouple is realized.
In particular implementations, the electromotive force after compensation sometimes still cannot be used satisfactorily.
Fig. 2 is a circuit diagram of a thermocouple temperature measuring system according to an embodiment of the present invention, as shown in fig. 2, on the basis of the foregoing embodiment, in this embodiment, the circuit diagram further includes: a second differential operational amplifier; as shown in U2 in fig. 2, the non-inverting input terminal of the second differential operational amplifier is connected to the thermocouple, and the inverting input terminal of the second differential operational amplifier is connected to the output terminal of the differential operational amplifier. The thermocouple in fig. 2 is amplified by U3, where R11 is the resistance required for grounding the thermocouple, so in this embodiment, the non-inverting input of the second differential operational amplifier is connected to the output of U3.
According to the thermocouple cold end compensation circuit provided by the embodiment of the utility model, the compensation voltage and the electromotive force generated by the thermocouple are combined through the second differential operational amplifier, and further amplification is carried out, so that the voltage can meet the requirement of subsequent use.
In the above embodiment, the resistor with a fixed resistance value is not limited, and in this embodiment, as shown in fig. 1, the resistor with a fixed resistance value includes:
a first resistor R1, a second resistor R2, a third resistor R3;
the first end of the first resistor and the first end of the third resistor are jointly used as the first end of the bridge voltage division circuit, the second end of the first resistor and the first end of the second resistor are jointly used as the second end of the bridge voltage division circuit, the second end of the third resistor and the first end of the platinum resistor are jointly used as the third end of the bridge voltage division circuit, and the second end of the second resistor and the second end of the platinum resistor are jointly used as the fourth end of the bridge voltage division circuit;
the resistance values of the first resistor and the third resistor are the same, and the resistance values of the second resistor and the platinum resistor are the same when the temperature environment is 0 ℃.
In the thermocouple cold junction compensation circuit provided by the embodiment of the utility model, the bridge-type voltage division circuit consists of three resistors with fixed resistance values and one platinum resistor, the resistance values of the first resistor and the third resistor are the same, the resistance values of the second resistor and the platinum resistor are the same when the temperature environment is 0 ℃, and if the output voltage of the second end of the bridge-type voltage division circuit is V2 and the output voltage of the third end of the bridge-type voltage division circuit is V1, the compensation voltage calculation formula is as follows
By adopting the technical scheme provided by the embodiment, the compensation voltage can be calculated more simply.
On the basis of the above embodiments, in this embodiment, a filter circuit is further included.
The input end of the filter circuit is connected with the second differential operational amplifier, and the filter circuit is used for suppressing and preventing interference.
According to the thermocouple cold end compensation circuit provided by the embodiment of the utility model, the filter circuit is additionally arranged, so that interference can be inhibited and prevented, and a signal is smoother.
The compensation circuit obtains voltage from the power supply, and becomes compensation voltage after carrying out operations such as voltage division, amplification and the like so as to compensate for the cold end of the thermocouple.
On the basis of the above embodiment, in this embodiment, the system further includes an alarm device;
the alarm device is connected with the power supply and used for giving out a prompt when the power supply outputs.
According to the thermocouple cold junction compensation circuit provided by the embodiment of the utility model, the alarm device is additionally arranged, and a prompt is sent when the power supply is output or not, so that an operator can know whether the power supply is output or not and whether the cold junction of the thermocouple is compensated or not.
In specific implementation, in order to know whether the power supply outputs more conveniently and quickly, on the basis of the above embodiment, in this embodiment, the alarm device includes: an indicator light and a buzzer;
the indicator light and the buzzer are connected with the power supply and used for displaying whether the power supply outputs or not.
According to the thermocouple cold end compensation circuit provided by the embodiment of the utility model, the alarm device adopts the indicator lamp and the buzzer, and the state change of the indicator lamp and the buzzer is controlled when the power supply outputs or not. For example, the indicator light flickers when the power supply outputs, the buzzer does not work, the indicator light is turned off when no output exists, and the buzzer buzzes, so that the operator can know whether the power supply outputs or not more conveniently and quickly, and the normal work of the circuit is guaranteed.
Finally, the embodiment of the utility model also provides a thermocouple temperature measuring system, which comprises the thermocouple cold end compensation circuit for performing cold end compensation on the thermocouple besides the thermocouple and other components. Since the above detailed description is made for each component, the detailed description is omitted here.
The thermocouple temperature measuring system provided by the embodiment of the utility model comprises a thermocouple cold end compensation circuit, wherein the circuit comprises a differential operational amplifier and a bridge type voltage division circuit; the bridge-type voltage division circuit is connected with a power supply and a differential operational amplifier, and the output voltage of the differential operational amplifier is used as cold end compensation voltage of the thermocouple. One bridge arm in the bridge type voltage division circuit comprises a resistive device with the resistance value adjustable along with the temperature, and the other bridge arms comprise resistors with fixed resistance values; the resistive device with the resistance value adjustable along with the temperature and the cold end of the thermocouple are in the same temperature environment. By adopting the scheme, when the cold ends of the thermocouples are in different temperature environments, the resistance value of the resistive device is changed along with the temperature change, so that the compensation voltage of the compensation circuit is changed, the dynamic compensation of the cold ends is realized, and the waste of human resources is reduced.
The cold end compensation circuit of the thermocouple and the thermocouple temperature measuring system provided by the utility model are described in detail above. The embodiments are described in a progressive manner in the specification, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.
It is further noted that, in the present specification, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
Claims (10)
1. A thermocouple cold end compensation circuit, comprising:
a differential operational amplifier and a bridge voltage divider circuit;
one bridge arm in the bridge type voltage division circuit comprises a resistive device with the resistance value adjustable along with the temperature, and the other bridge arms comprise resistors with fixed resistance values; the resistance device with the resistance value adjustable along with the temperature and the cold end of the thermocouple are in the same temperature environment;
the first end of the bridge-type voltage division circuit is connected with a power supply, the second end of the bridge-type voltage division circuit is connected with the non-inverting input end of the differential operational amplifier, the third end of the bridge-type voltage division circuit is connected with the inverting input end of the differential operational amplifier, and the fourth end of the bridge-type voltage division circuit is grounded;
and the output voltage of the differential operational amplifier is used as the cold end compensation voltage of the thermocouple.
2. The thermocouple cold end compensation circuit of claim 1, wherein the resistive device having a resistance that is adjustable with temperature is a platinum resistor;
the first end of the platinum resistor is used as the third end of the bridge-type voltage division circuit and connected with the inverting input end of the differential operational amplifier, and the second end of the platinum resistor is used as the fourth end of the bridge-type voltage division circuit and grounded.
3. The thermocouple cold end compensation circuit of claim 1, wherein said resistive device having a resistance that is adjustable with temperature comprises:
the temperature sensor, the control chip, the switches and the resistors with corresponding quantity; wherein the resistances of the resistors are all different;
the temperature sensor is connected with the control chip, the control chip is connected with the plurality of switches, the switches are connected with the resistors in a one-to-one correspondence mode, and the control chip controls and selects the resistors with different resistance values to be connected into the bridge arm through temperature signals sent by the temperature sensor.
4. The thermocouple cold end compensation circuit of claim 2, further comprising:
a temperature display instrument;
the temperature display instrument is connected with the output end of the differential operational amplifier and the thermocouple.
5. The thermocouple cold end compensation circuit of claim 2, further comprising:
a second differential operational amplifier;
the non-inverting input end of the second differential operational amplifier is connected with the thermocouple, and the inverting input end of the second differential operational amplifier is connected with the output end of the differential operational amplifier.
6. The thermocouple cold end compensation circuit of claim 2, wherein the fixed resistance resistor comprises:
a first resistor, a second resistor and a third resistor;
the first end of the first resistor and the first end of the third resistor are commonly used as the first end of the bridge voltage division circuit, the second end of the first resistor and the first end of the second resistor are commonly used as the second end of the bridge voltage division circuit, the second end of the third resistor and the first end of the platinum resistor are commonly used as the third end of the bridge voltage division circuit, and the second end of the second resistor and the second end of the platinum resistor are commonly used as the fourth end of the bridge voltage division circuit;
the resistance values of the first resistor and the third resistor are the same, and the resistance values of the second resistor and the platinum resistor are the same when the temperature environment is 0 ℃.
7. The thermocouple cold end compensation circuit of claim 5, further comprising:
a filter circuit;
the input end of the filter circuit is connected with the second differential operational amplifier, and the filter circuit is used for suppressing and preventing interference.
8. The thermocouple cold end compensation circuit of claim 1, further comprising:
an alarm device;
the alarm device is connected with the power supply and used for giving out a prompt when the power supply outputs or not.
9. The thermocouple cold end compensation circuit of claim 8, wherein said alarm means comprises:
an indicator light and a buzzer;
the indicator light and the buzzer are connected with the power supply and used for displaying whether the power supply outputs or not.
10. A thermocouple thermometry system comprising the thermocouple cold end compensation circuit of any one of claims 1 through 9.
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| CN202122046416.5U CN215865540U (en) | 2021-08-27 | 2021-08-27 | Thermocouple cold junction compensation circuit and thermocouple temperature measurement system |
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| CN202122046416.5U CN215865540U (en) | 2021-08-27 | 2021-08-27 | Thermocouple cold junction compensation circuit and thermocouple temperature measurement system |
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