CN216562202U

CN216562202U - Signal processing circuit board for teaching

Info

Publication number: CN216562202U
Application number: CN202123372697.XU
Authority: CN
Inventors: 李铭; 张育林; 王娜; 黄宝娟; 王明伟; 毕文婷; 张泽
Original assignee: Xian Jiaotong University
Current assignee: Xian Jiaotong University
Priority date: 2021-12-29
Filing date: 2021-12-29
Publication date: 2022-05-17
Anticipated expiration: 2031-12-29

Abstract

A signal processing circuit board for teaching comprises training modules of seven signal processing circuits, namely a single-ended input amplifying circuit module A1, an LM324 operational amplifier module A2, a differential input amplifying circuit module A3, an optional commonly-used electronic element module A4, a shaping circuit module A5, a frequency/voltage conversion circuit module A6 and an alarm circuit module A7; each circuit module is independently arranged, electronic components of the circuit modules A1-A5 are discrete components, and pins of the electronic components are provided with terminals; circuit module a6 has 9 terminals and circuit module a7 has 5 terminals; the device can carry out parameter test or circuit connection through a lead with a plug; the utility model is convenient for students to test the characteristics of elements, freely selects elements and sets up a signal processing circuit according to the requirements; the student can conveniently understand and master the characteristics of the signal processing circuit by combining with measuring instruments such as a signal generator, an oscilloscope and the like, and the innovative practice items are expanded.

Description

Signal processing circuit board for teaching

Technical Field

The utility model relates to a circuit board, in particular to a signal processing circuit board for teaching.

Background

The signal processing circuit with various functions can be formed by utilizing an integrated operational amplifier or a special analog integrated circuit and matching with a small number of external elements. The main functions of the signal processing circuit include signal amplification, signal filtering, impedance matching, level conversion, nonlinear compensation, current/voltage conversion, voltage/frequency conversion and the like, and the signal processing circuit is an indispensable important component in a measurement and control system. Signal processing circuitry often converts analog signals from sensors into signals suitable for data acquisition, process control, and calculations to be performed on the inputs of analog-to-digital converters (ADCs). The ADC then digitizes the analog signal and sends the digital signal to a microcontroller or other digital device for data processing by the system. The design realization of the signal processing circuit is a very important ring in a measurement and control practice course, the capability of students in circuit design is examined, the capability of circuit building is built according to a circuit diagram, the capability of testing the circuit and troubleshooting errors is also concerned, and meanwhile, the building of the whole measuring system is also concerned. Therefore, it is necessary to design the signal processing circuit board according to the teaching. The signal processing circuit board for teaching has single function, does not have an integrated circuit board, and when the circuit board with single function is used in a combined mode, wiring trouble is often caused during demonstration due to the fact that wiring ends are not matched.

Disclosure of Invention

In order to overcome the defects of the prior art, the utility model aims to provide a signal processing circuit board for teaching, which is divided into seven modules, wherein the modules are independent from each other, a common separated element is adopted, and wiring terminals are arranged at two ends of the element, so that parameter testing or circuit connection can be performed through a lead with a plug, and the targeted teaching is convenient.

In order to achieve the purpose, the utility model adopts the technical scheme that:

a signal processing circuit board for teaching comprises training modules of seven signal processing circuits, which are respectively: a single-ended input amplifying circuit module A1, an LM324 operational amplifier module A2, a differential input amplifying circuit module A3 arranged on the upper part of the circuit board; an optional common electronic component module a4 disposed in the middle of the circuit board; a shaping circuit module A5, a frequency/voltage conversion module A6 and an alarm circuit module A7 which are arranged at the lower part of the circuit board; the modules are independent from each other; the pins of the components are provided with wiring terminals which can carry out parameter test or circuit connection through the lead with the plug; the seven modules share a ground GND.

The single-ended input amplification circuit module A1 is arranged on the left side of the upper part of the circuit board and comprises a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a potentiometer W1, a potentiometer W2, a potentiometer W3, a capacitor C1, a capacitor C2, an AD590 and an OP07 operational amplifier chip O1 which are independently designed; two ends of the resistor, the potentiometer, the capacitor and the AD590 are connected with the connecting terminal, and two input ends, two power supply ends and one output end of the OP07 operational amplifier chip O1 are respectively connected with the connecting terminal; the common ground GND is located in the lower left corner of the module and has two terminals.

The LM324 operational amplifier module A2 is arranged in the middle of the upper part of the circuit board and comprises an LM324 operational amplifier chip O2 and 10 terminals of two groups of operational amplifiers; the LM324 operational amplifier is arranged in the middle of the module, wherein 5 terminals of one group of operational amplifiers are arranged at the upper left side of the module, and 5 terminals of the other group of operational amplifiers are arranged at the lower right side of the module; the common ground GND is located in the lower left corner of the module and has two terminals.

The differential input amplification circuit module A3 is arranged on the right side of the upper part of the circuit board and comprises a resistor R8, a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a potentiometer W4, a potentiometer W5 and an OP07 operational amplifier chip O3; the two ends of the resistor and the potentiometer are connected with the wiring terminal, and the two input ends, the two power supply ends and one output end of the operational amplifier are respectively connected with the wiring terminal; the common ground GND is located in the lower left corner of the module and has two terminals.

The selectable common electronic component module A4 comprises a resistor R15, a resistor R16, a resistor R17, a resistor R18, a resistor R19, a resistor R20, a resistor R21, a resistor R22, a resistor R23, a resistor R24, a potentiometer W6, a potentiometer W7, a potentiometer W8, a potentiometer W9, a capacitor C3, a capacitor C4, a capacitor C5, a light-emitting diode LED1, a diode D1, a diode D2, a triode Q1 and a triode Q2; the two ends of the resistor, the potentiometer, the capacitor, the light emitting diode and the diode are connected with the wiring terminal; wherein, the three ends of the triode are connected with the wiring terminal.

The shaping circuit module A5 is arranged in the middle of the lower part of the circuit board and comprises: resistor R30, resistor R31, resistor R32, terminal + V, terminal-V, terminal GND, and OP07 operational amplifier chip O4; wherein, both ends of the resistor are connected with the connecting terminal; the common ground GND has two terminals located in the lower left corner of the module.

The frequency/voltage conversion module A6 is arranged on the left side of the lower part of the circuit board and comprises: a resistor R25, a resistor R26, a resistor R27, a resistor R28, a resistor R29, a potentiometer W10, a diode D3, a capacitor C6, a capacitor C7, a capacitor C8, a capacitor C9 and an LM2907 chip; one end of the resistor R25 is connected with the terminal fin, and the other end of the resistor R25 is connected with the No. 11 pin of the LM2907 chip and the negative electrode of the diode D3; the anode of the diode D3 is connected with the ground line GND; one end of the resistor R26 is connected with the +10V connecting terminal, and the other end of the resistor R26 is connected with the resistor R27 and the No. 1 pin of the LM2907 chip; the other end of the resistor R27 is connected with the ground wire GND; one end of a capacitor C6 is connected with a No. 2 pin of the LM2907 chip, and the other end of the capacitor C6 is connected with a ground wire GND; one end of the resistor R28 is connected with the potentiometer W10, and the other end of the resistor R28 is connected with a No. 3 pin of the LM2907 chip; the other end of the potentiometer W10 is connected with a ground wire GND; the No. 3 pin and the No. 4 pin of the LM2907 chip are connected with a terminal J8; one end of the capacitor C7 is connected with the terminal J6, and the other end of the capacitor C7 is connected with the ground line GND; one end of the capacitor C8 is connected with the terminal J5, and the other end of the capacitor C8 is connected with the ground line GND; one end of the capacitor C9 is connected with the terminal J7, and the other end of the capacitor C9 is connected with the ground line GND; one end of the resistor R29 is connected with the No. 5 pin and the No. 10 pin of the LM2907 chip and the output of the terminal UO, and the other end of the resistor R29 is connected with the ground wire GND; no. 6, No. 7, No. 8, No. 9, No. 12, No. 13 and No. 14 pins of the LM2907 chip are vacant and are not connected; the common ground GND is located in the lower left corner of the module and has two terminals.

The alarm circuit module A7 is arranged on the right side of the lower part of the circuit board and comprises: a resistor R33, a resistor R34, a resistor R35, a resistor R36, a potentiometer W11, a potentiometer W12, a potentiometer W13, a light emitting diode LED2, a light emitting diode LED3, an LM324 operational amplifier chip O5 and an SN74F04N inverter chip; one end of the resistor R33 is connected with the fin input terminal, and the other end of the resistor R33 is connected with the No. 3 pin non-inverting input end of the LM 324; one end of a resistor R34 is connected with a + V terminal, the other end of a resistor R34 is connected with a terminal J1 and a No. 2 pin inverting input end of an LM324, one end of a potentiometer W11 is connected with a terminal J1, and the other end of a potentiometer W11 is connected with a ground wire GND; the positive power supply end of the No. 4 pin and the GND of the No. 11 pin of the LM324 are respectively connected with the + V terminal and the ground wire GND; the No. 1 pin at the output end of the LM324 is connected with a terminal J2; pin number 1 of SN74F04N is connected to terminal J2, and pin number 2 is connected to pin number 3 and terminal J3; one end of the resistor R35 is connected with a terminal J3, and the other end of the resistor R35 is connected with a potentiometer W12; the other end of W12 is connected with LED 2; the other end of the light emitting diode LED2 is connected with the ground wire GND; pin 4 of SN74F04N is connected to terminal J4; one end of the resistor R36 is connected with a terminal J4, and the other end of the resistor R36 is connected with a potentiometer W13; the other end of the potentiometer W13 is connected with a light-emitting diode LED 3; the other end of the light emitting diode LED3 is connected with the ground wire GND; the common ground wire GND is positioned at the lower left corner of the circuit module and is provided with two wiring terminals; terminal + V is located in the lower left corner of the circuit module.

The utility model has the beneficial effects that:

1. the circuit board adopts common electronic components, is low in cost, adopts a separated element, has wiring ends at two ends of the element, and can carry out parameter test or circuit connection through a lead with a plug.

2. The circuit board is divided into seven modules, the modules are mutually independent, and targeted teaching is conveniently carried out.

3. Each module of the circuit board is provided with a plurality of classes and a large number of components, and therefore extensive training is developed on the basis that students who learn the rest can complete basic training conveniently, and the divergent thinking and innovation ability are improved.

Drawings

Fig. 1 is a block diagram of the structural layout of the present invention.

Fig. 2 is a general circuit diagram of the present invention.

Fig. 3 is a circuit diagram of an in-phase amplifier.

Fig. 4 is a current/voltage conversion circuit diagram.

Fig. 5 is a circuit diagram of an inverting input adder.

Fig. 6 is a differential amplifier circuit diagram.

Fig. 7 is a voltage comparator circuit.

Fig. 8 is an integration circuit.

Fig. 9 is a differentiating circuit.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples.

Referring to fig. 1 and 2, the present invention is a signal processing circuit board for teaching, on which more than 70 electronic components and chips are mounted. The training module comprises seven signal processing circuits, which are respectively: a single-end input amplifying circuit module A1 (left upper side), an LM324 operational amplifier module A2 (upper middle part), a differential input amplifying circuit module A3 (right upper side), an optional common electronic element module A4 (middle part), a shaping circuit module A5 (lower middle part), a frequency/voltage conversion module A6 (left lower side), and an alarm circuit module A7 (right lower side). All modules are independent of each other; the pins of the components are provided with wiring terminals which can carry out parameter test or circuit connection through the lead with the plug; the seven modules share a ground GND.

Referring to fig. 2, the single-ended input amplification circuit module a1 is disposed on the left side of the upper portion of the circuit board, and includes an independently designed resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a potentiometer W1, a potentiometer W2, a potentiometer W3, a capacitor C1, a capacitor C2, an AD590, and an OP07 operational amplifier chip O1; two ends of the resistor, the potentiometer, the capacitor and the AD590 are connected with the connecting terminal, and two input ends, two power supply ends and one output end of the OP07 operational amplifier chip O1 are respectively connected with the connecting terminal; the common ground GND is located in the lower left corner of the module and has two terminals.

The alarm circuit module A7 is arranged at the right side of the lower part of the circuit board and comprises: a resistor R33, a resistor R34, a resistor R35, a resistor R36, a potentiometer W11, a potentiometer W12, a potentiometer W13, a light emitting diode LED2, a light emitting diode LED3, an LM324 operational amplifier chip O5 and an SN74F04N inverter chip; one end of the resistor R33 is connected with the fin input terminal, and the other end of the resistor R33 is connected with the No. 3 pin non-inverting input end of the LM 324; one end of a resistor R34 is connected with a + V terminal, the other end of a resistor R34 is connected with a terminal J1 and a No. 2 pin inverting input end of an LM324, one end of a potentiometer W11 is connected with a terminal J1, and the other end of a potentiometer W11 is connected with a ground wire GND; the positive power supply end of the No. 4 pin and the GND of the No. 11 pin of the LM324 are respectively connected with the + V terminal and the ground wire GND; the No. 1 pin at the output end of the LM324 is connected with a terminal J2; pin number 1 of SN74F04N is connected to terminal J2, and pin number 2 is connected to pin number 3 and terminal J3; one end of the resistor R35 is connected with a terminal J3, and the other end of the resistor R35 is connected with a potentiometer W12; the other end of W12 is connected with LED 2; the other end of the light emitting diode LED2 is connected with the ground wire GND; pin 4 of SN74F04N is connected to terminal J4; one end of the resistor R36 is connected with a terminal J4, and the other end of the resistor R36 is connected with a potentiometer W13; the other end of the potentiometer W13 is connected with a light-emitting diode LED 3; the other end of the light emitting diode LED3 is connected with the ground wire GND; the common ground wire GND is positioned at the lower left corner of the circuit module and is provided with two wiring terminals; terminal + V is located in the lower left corner of the circuit module.

The working principle of the utility model is as follows:

the following lists nine applications (but not limited to nine applications) of the utility model for teaching, in which students can use the device to build a circuit according to experimental requirements or to realize a new circuit of innovative ideas.

Referring to fig. 2, a frequency/voltage conversion module a6 is selected, a periodic signal is input from a fin input terminal, a terminal J8 on a circuit board is connected with a terminal J6, a Uo output terminal is connected with a universal meter, a +10v power supply is used for supplying power, the size of a potentiometer W10 is adjusted, the purpose of converting the frequency of the input signal into a voltage value and outputting the voltage value is achieved, and a linear relation is formed; the input signal is unchanged, the power supply of the power supply is unchanged, the output of the UO is connected with an oscilloscope, a terminal J8 is connected with a terminal J5 and a terminal J7 respectively, the ripple phenomenon is observed, and the influence of different capacitance parameters on the output signal UO is understood; the power supply of the power supply is unchanged, the output of the Uo is connected with an oscilloscope, a terminal J8 is connected with a terminal J5 and a terminal J7 respectively, the frequency of an input signal is changed from a frequency value, the frequency value is changed greatly, and the influence of the dynamic characteristics of different capacitance parameter systems is observed.

Referring to fig. 2, an alarm circuit module a7 is selected, an input signal is input from a fin terminal, and the sizes of a potentiometer W11, a potentiometer W12 and a potentiometer W13 are set and adjusted, so that a light emitting diode LED2 or a light emitting diode LED3 can be lightened, and an alarm can be realized; leads can be led out from the terminal J1, the terminal J2, the terminal J3 and the terminal J4 to measure the voltage or the current. The output voltage of the frequency/voltage conversion circuit and the output voltage of the current/voltage conversion circuit can be used as the input signal of the alarm circuit, the parameter value is set, and the light emitting diode LED2 and the light emitting diode LED3 are respectively used as display lamps exceeding the threshold value and the normal range to realize alarm. The student can also use the circuit to realize alarming according to the requirement.

Referring to fig. 3, the single-ended amplifier module a1 and the optional common electronic module a4 are used to provide resistors and operational amplifiers, and the circuits are connected according to fig. 3, so that the output voltage Vout is (R1+ R2)/R1 times of the input voltage Vin, and the phases are the same. Adjusting the amplitude of the input signal Vin, observing the change of the output signal Vout, recording the information of the input signal when the output signal is distorted, and understanding the principle of the operational amplifier.

Referring to fig. 3, the operational amplifier provided by the LM324 operational amplifier module a2 and the optional common electronic component module a4 and the resistance provided by the single-ended amplifier circuit module a1 are selected, the circuit is connected according to fig. 3, the amplitude of the input signal Vin is adjusted, the change of the output signal Vout is observed, the information of the input signal when the output signal is distorted is recorded, and the information is compared with the experimental result using the OP07 operational amplifier, so as to reach the conclusion.

Referring to fig. 4, the resistor, the potentiometer and the operational amplifier provided by the single-ended amplifier circuit module a1 and the optional commonly used electronic component module a4 are selected, the circuit is connected according to fig. 4, the current-to-voltage conversion is realized, and the magnitudes of the potentiometer W1 and the potentiometer W2 are manually adjusted, so that the output voltage Vout corresponds to the linear relationship of the integrated temperature sensor AD 590.

Referring to fig. 5, the resistors, the potentiometers, and the operational amplifiers provided by the differential input amplifier circuit module A3 and the optional conventional electronic component module a4 are selected, for example, the resistors R1 and R2 are selected to have the same resistance value, the series resistance value of the resistor R3 and the potentiometer W1 is selected to be the same as the series resistance value of the resistor R4 and the potentiometer W2 (measurement can be performed by using a universal meter), and the connection is performed according to fig. 5, so that a differential input proportional circuit can be realized, that is, the output uo is several times (ui1-ui 2).

Referring to fig. 6, the resistors, potentiometers and operational amplifiers provided by the differential input amplifier circuit block A3 and the optional common electronics block a4 are connected as shown in fig. 6 to implement an adder circuit with inverting inputs, the output uo is (Rf/R1) times the sum of the two inputs (ui1+ ui2), and the output waveform is in phase opposition to the input waveform.

Referring to fig. 7, a resistor, a potentiometer and an operational amplifier provided by a shaping circuit module a5 and an optional commonly used electronic element module a4 are selected and connected according to fig. 7, an input signal is connected with a periodic signal, a voltage comparator can be realized, the size of W1 is adjusted, the output voltage can be observed to change in different stages, direct current close to positive voltage Vcc, rectangular wave with the same frequency as the input signal and different duty ratios and direct current close to GND are provided, the relationship between the input signal and a comparison level Vr is analyzed, and the meaning of voltage comparison is understood according to the principle of the operational amplifier.

Referring to fig. 8, the resistors, capacitors and operational amplifiers provided by the shaping circuit module a5 and the optional conventional electronic component module a4 are connected according to fig. 8, so as to implement an integrating circuit. The circuit is used for realizing square wave-triangular wave conversion, namely when an input signal selects a square wave signal, an output signal is a triangular wave with the same frequency.

Referring to fig. 9, the resistors, capacitors and operational amplifiers provided by the shaping circuit module a5 and the optional conventional electronic component module a4 are connected according to fig. 9, thereby realizing a differential circuit.

In teaching, the signal processing circuit board is designed for students to learn and master various circuit types of signal processing. The utility model comprises seven training modules of signal processing circuit, which are respectively: the circuit comprises a single-ended input amplifying circuit module A1, an LM324 operational amplifier module A2, a differential input amplifying circuit module A3, an optional common electronic element module A4, a shaping circuit module A5, a frequency/voltage conversion module A6 and an alarm circuit module A7. In addition to the above examples, circuits such as sine wave, square wave, triangular wave signal generators, low-pass active filter and the like can also be realized.

Claims

1. The signal processing circuit board for teaching is characterized by comprising training modules of seven signal processing circuits, wherein the training modules are respectively as follows: the single-ended input amplifying circuit module A1, the LM324 operational amplifier module A2 and the differential input amplifying circuit module A3 are arranged on the upper part of the circuit board; an optional common electronic component module a4 disposed in the middle of the circuit board; a shaping circuit module A5, a frequency/voltage conversion module A6 and an alarm circuit module A7 which are arranged at the lower part of the circuit board; the modules are independent from each other; the pins of the components are provided with wiring terminals which can carry out parameter test or circuit connection through the lead with the plug; the seven modules share a ground GND.

2. The signal processing circuit board for teaching of claim 1, wherein the single-ended input amplification circuit module a1 is disposed on the left side of the upper portion of the circuit board, and comprises independently designed resistors R1, R2, R3, R4, R5, R6, R7, W1, W2, W3, C1, C2, AD590, and OP07 operational amplifier chip O1; two ends of the resistor, the potentiometer, the capacitor and the AD590 are connected with the connecting terminal, and two input ends, two power supply ends and one output end of the OP07 operational amplifier chip O1 are respectively connected with the connecting terminal; the common ground GND is located in the lower left corner of the module and has two terminals.

3. The signal processing circuit board for teaching of claim 1, wherein said LM324 operational amplifier module a2 is disposed in the middle of the upper portion of the circuit board, comprising one LM324 operational amplifier chip O2 and 10 terminals of two sets of operational amplifiers; the LM324 operational amplifier is arranged in the middle of the module, wherein 5 terminals of one group of operational amplifiers are arranged at the upper left side of the module, and 5 terminals of the other group of operational amplifiers are arranged at the lower right side of the module; the common ground GND is located in the lower left corner of the module and has two terminals.

4. The signal processing circuit board for teaching of claim 1, wherein the differential input amplifying circuit module a3 is arranged on the right side of the upper part of the circuit board and comprises a resistor R8, a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a potentiometer W4, a potentiometer W5 and an OP07 operational amplifier chip O3; the two ends of the resistor and the potentiometer are connected with the wiring terminal, and the two input ends, the two power supply ends and one output end of the operational amplifier are respectively connected with the wiring terminal; the common ground GND is located in the lower left corner of the module and has two terminals.

5. The signal processing circuit board for teaching of claim 1, wherein said optional common electronic component module a4 comprises a resistor R15, a resistor R16, a resistor R17, a resistor R18, a resistor R19, a resistor R20, a resistor R21, a resistor R22, a resistor R23, a resistor R24, a potentiometer W6, a potentiometer W7, a potentiometer W8, a potentiometer W9, a capacitor C3, a capacitor C4, a capacitor C5, a light emitting diode LED1, a diode D1, a diode D2, a triode Q1, and a triode Q2; the two ends of the resistor, the potentiometer, the capacitor, the light emitting diode and the diode are connected with the wiring terminal; wherein, the three ends of the triode are connected with the wiring terminal.

6. The signal processing circuit board for teaching of claim 1, wherein said shaping circuit module a5 is disposed in the middle of the lower part of the circuit board, comprising: resistor R30, resistor R31, resistor R32, terminal + V, terminal-V, terminal GND, and OP07 operational amplifier chip O4; wherein, both ends of the resistor are connected with the connecting terminal; the common ground GND has two terminals located in the lower left corner of the module.

7. The signal processing circuit board for teaching of claim 1, wherein said frequency/voltage conversion module a6 is disposed at the left side of the lower portion of the circuit board, comprising: a resistor R25, a resistor R26, a resistor R27, a resistor R28, a resistor R29, a potentiometer W10, a diode D3, a capacitor C6, a capacitor C7, a capacitor C8, a capacitor C9 and an LM2907 chip; one end of the resistor R25 is connected with the terminal fin, and the other end of the resistor R25 is connected with the No. 11 pin of the LM2907 chip and the negative electrode of the diode D3; the anode of the diode D3 is connected with the ground line GND; one end of the resistor R26 is connected with the +10V connecting terminal, and the other end of the resistor R26 is connected with the resistor R27 and the No. 1 pin of the LM2907 chip; the other end of the resistor R27 is connected with the ground wire GND; one end of a capacitor C6 is connected with a No. 2 pin of the LM2907 chip, and the other end of the capacitor C6 is connected with a ground wire GND; one end of the resistor R28 is connected with the potentiometer W10, and the other end of the resistor R28 is connected with a No. 3 pin of the LM2907 chip; the other end of the potentiometer W10 is connected with a ground wire GND; the No. 3 pin and the No. 4 pin of the LM2907 chip are connected with a terminal J8; one end of the capacitor C7 is connected with the terminal J6, and the other end of the capacitor C7 is connected with the ground line GND; one end of the capacitor C8 is connected with the terminal J5, and the other end of the capacitor C8 is connected with the ground line GND; one end of the capacitor C9 is connected with the terminal J7, and the other end of the capacitor C9 is connected with the ground line GND; one end of the resistor R29 is connected with the No. 5 pin and the No. 10 pin of the LM2907 chip and the output of the terminal UO, and the other end of the resistor R29 is connected with the ground wire GND; no. 6, No. 7, No. 8, No. 9, No. 12, No. 13 and No. 14 pins of the LM2907 chip are vacant and are not connected; the common ground GND is located in the lower left corner of the module and has two terminals.

8. The signal processing circuit board for teaching of claim 1, wherein the alarm circuit module a7 is arranged at the right side of the lower part of the circuit board and comprises: a resistor R33, a resistor R34, a resistor R35, a resistor R36, a potentiometer W11, a potentiometer W12, a potentiometer W13, a light emitting diode LED2, a light emitting diode LED3, an LM324 operational amplifier chip O5 and an SN74F04N inverter chip; one end of the resistor R33 is connected with the fin input terminal, and the other end of the resistor R33 is connected with the No. 3 pin non-inverting input end of the LM 324; one end of a resistor R34 is connected with a + V terminal, the other end of a resistor R34 is connected with a terminal J1 and a No. 2 pin inverting input end of an LM324, one end of a potentiometer W11 is connected with a terminal J1, and the other end of a potentiometer W11 is connected with a ground wire GND; the positive power supply end of the No. 4 pin and the GND of the No. 11 pin of the LM324 are respectively connected with the + V terminal and the ground wire GND; the No. 1 pin at the output end of the LM324 is connected with a terminal J2; pin 1 of SN74F04N is connected to terminal J2, and pin 2 is connected to pin 3 and terminal J3; one end of the resistor R35 is connected with a terminal J3, and the other end of the resistor R35 is connected with a potentiometer W12; the other end of W12 is connected with LED 2; the other end of the light emitting diode LED2 is connected with the ground wire GND; pin 4 of SN74F04N is connected to terminal J4; one end of the resistor R36 is connected with a terminal J4, and the other end of the resistor R36 is connected with a potentiometer W13; the other end of the potentiometer W13 is connected with a light-emitting diode LED 3; the other end of the light emitting diode LED3 is connected with the ground wire GND; the common ground wire GND is positioned at the lower left corner of the circuit module and is provided with two wiring terminals; terminal + V is located in the lower left corner of the circuit module.