Differential amplification circuit demonstration board

Abstract

The utility model belongs to the technical field of teaching aid circuit design, and provides a differential amplification circuit demonstration board, which is characterized in that a differential amplifier, a zero setting potentiometer, a voltage stabilizing unit and a plurality of change-over switches are integrated on the same circuit substrate, and a plurality of test points are integrated at specific positions of a circuit. An external power supply, a signal source, a multimeter and the like are selectively accessed through a plurality of change-over switches, and the connection to an oscilloscope through a plurality of test points is supported, so that teachers and students can directly operate and demonstrate the functional characteristics of static working point measurement, zero setting, common mode suppression, differential mode amplification, single-ended input, nonlinear distortion and the like. The technical problem that the function and performance characteristics of the differential amplification circuit are not easy to demonstrate is solved, and the function and performance characteristics of the differential amplification circuit can be demonstrated efficiently and flexibly.

Description

TECHNICAL FIELD

[0001] The utility model belongs to teaching aid circuit design technical field relates to a differential amplifier circuit demonstration board. BACKGROUND

[0002] As one of the core circuits of analog electronic technology, differential amplifier circuit is widely used in industrial measurement and control, communication system and analog integrated circuit fields due to its excellent common-mode interference suppression capability and differential-mode signal amplification characteristics. For example, in the sensor signal acquisition scene, it can effectively amplify the weak differential signal output by the sensor and suppress the common-mode interference caused by environmental noise. In high-speed communication systems, differential transmission signals can be amplified and shaped.

[0003] However, in the teaching demonstration link, the circuit products used for related teaching demonstration have many inconveniences. Traditional teaching often uses discrete components and manually plugs in wires to build circuits, which is not only complex in wiring and tedious in parameter adjustment, but also difficult for students to intuitively distinguish the mechanism of common-mode signals and differential-mode signals. During the experiment, the circuit is easily disturbed by external interference, and troubleshooting is time-consuming, which leads students to understand the circuit principle at the theoretical level and makes it difficult for them to master the working nature through efficient and intuitive demonstration, greatly affecting the teaching effect and knowledge transmission efficiency. Therefore, it is urgent to develop a more convenient and intuitive teaching demonstration scheme to break through this dilemma. Therefore, how to efficiently and flexibly demonstrate the function and performance characteristics of the differential amplifier circuit has become one of the technical problems to be solved. UTILITY MODEL CONTENTS

[0004] In view of the problems existing in the above-mentioned traditional technology, the utility model provides a differential amplifier circuit demonstration board, which can efficiently and flexibly demonstrate the function and performance characteristics of the differential amplifier circuit.

[0005] In order to achieve the above-mentioned purpose, the utility model embodiment adopts the following technical scheme:

[0006] A differential amplifier circuit demonstration board is provided, which comprises a substrate, test points AIN1, AIN2, AIN3 and AIN4 integrated on the substrate, a differential amplifier, a zero-setting potentiometer, a voltage stabilizing unit, switching switches SW1, SW2 and SW3.

[0007] The differential pair tubes in the differential amplifier are connected through a zero setting potentiometer, the sliding end of the zero setting potentiometer is connected to a voltage stabilizing unit, the test point AIN1 and the switching switch SW1 are connected to the first input end of the differential amplifier, the test point AIN2 and the switching switch SW2 are connected to the second input end of the differential amplifier, the test point AIN3 is connected to the first output end of the differential amplifier, the test point AIN4 is connected to the second output end of the differential amplifier, the test point AIN1, the test point AIN2, the test point AIN3 and the test point AIN4 are respectively connected to each signal channel of an oscilloscope, and the power supply ends of the differential amplifier and the voltage stabilizing unit are respectively connected to a power supply.

[0008] The switching switch SW1 is used for selecting to access a first signal source, ground or the second input end of the differential amplifier, the switching switch SW2 is used for selecting to access a second signal source, ground or the first input end of the differential amplifier, and the switching switch SW3 is used for connecting the collector, the base and the emitter of the transistor Q1 in the differential pair tubes to a multimeter.

[0009] In one of the embodiments, the voltage stabilizing unit comprises a transistor Q, a resistor R5, a voltage stabilizing tube ZD and a resistor R6.

[0010] The collector of the transistor Q is connected to the sliding end of the zero setting potentiometer, the emitter of the transistor Q is connected to one end of the resistor R5, the other end of the resistor R5 and the anode of the voltage stabilizing tube ZD are both used for connecting to the negative end of a power supply, the base of the transistor Q is respectively connected to the cathode of the voltage stabilizing tube ZD and one end of the resistor R6, and the other end of the resistor R6 is used for connecting to the positive end of the power supply.

[0011] In one of the embodiments, the differential amplification circuit demonstration board further comprises a switching switch SW4 and a power supply adapter integrated on the substrate, the switching switch SW4 is respectively connected to the power supply adapter, the power supply end of the differential amplifier and the power supply end of the voltage stabilizing unit, the power supply adapter is used for connecting to a power supply, and the switching switch SW4 is used for switching the access of a 5-volt power supply or a 12-volt power supply.

[0012] In one of the embodiments, the differential amplification circuit demonstration board further comprises an oscilloscope adapter integrated on the substrate, the oscilloscope adapter is respectively connected to the test point AIN1, the test point AIN2, the test point AIN3 and the test point AIN4, and the oscilloscope adapter is used for connecting to an oscilloscope.

[0013] In one of the embodiments, the differential amplification circuit demonstration board further comprises a signal source adapter integrated on the substrate, the signal source adapter is respectively connected to the switching switch SW1 and the switching switch SW2, and the signal source adapter is used for connecting to external first and second signal sources.

[0014] In one of the embodiments, the differential amplifier circuit demonstration board further comprises a multimeter adapter integrated on the substrate, the multimeter adapter is connected with the switch SW3, and the multimeter adapter is used for connecting a multimeter.

[0015] In one of the embodiments, the power adapter, the oscilloscope adapter, the signal source adapter and the multimeter adapter are all DuPont wire adapters.

[0016] One of the technical solutions has the following advantages and beneficial effects:

[0017] The differential amplifier circuit demonstration board has the following advantages and beneficial effects: The differential amplifier circuit demonstration board has the following advantages and beneficial effects:

[0018]

[0019] Figure 1 It is a real circuit structure schematic diagram of the differential amplifier circuit demonstration board in one of the embodiments;

[0020] Figure 2 It is a zero setting waveform diagram displayed by the oscilloscope in one of the embodiments;

[0021] Figure 3 It is a waveform diagram displayed by the oscilloscope in one of the embodiments under the demonstration of common mode rejection;

[0022] Figure 4 It is a waveform diagram displayed by the oscilloscope in one of the embodiments under the demonstration of differential mode amplification;

[0023] Figure 5 It is a waveform diagram displayed by the oscilloscope in one of the embodiments under the demonstration of single-ended input;

[0024] Figure 6 ​A waveform diagram for a scope display demonstrating non-linear distortion in one embodiment. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Unless otherwise defined, all technical and scientific terms used in the present application are the same as those commonly understood by those skilled in the art of the present application. The terms used in the specification of the present application are only for the purpose of describing the specific embodiments and are not intended to limit the present application.

[0026] It should be noted that the term "embodiment" mentioned in the present application means that the specific features, structures or characteristics described in conjunction with the embodiments can be included in at least one embodiment of the present application. The phrase is shown at various places in the specification does not necessarily refer to the same embodiment, nor is it independent or alternative to other embodiments. Those skilled in the art can understand that the embodiments described in the present application can be combined with other embodiments. The term "and / or" used in the specification of the present application means any combination of one or more of the associated listed items and all possible combinations, and includes these combinations.

[0027] The embodiments of the present application will be described in detail below with reference to the drawings in the embodiments of the present application.

[0028] In one embodiment, as Figure 1As shown, a differential amplifier circuit demonstration board is provided, including a substrate (i.e. blue circuit board), test point AIN1, test point AIN2, test point AIN3, test point AIN4, differential amplifier (consisting of resistors R1, R2, R3, R4 and differential pair tube), zero adjustment potentiometer PR, voltage stabilizing unit, switching switch SW1, switching switch SW2 and switching switch SW3 integrated on the substrate. The differential pair tube (consisting of transistor Q1 and transistor Q2) in the differential amplifier is connected through the zero adjustment potentiometer PR, the sliding end of the zero adjustment potentiometer PR is connected to the voltage stabilizing unit, the test point AIN1 and the switching switch SW1 are both connected to the first input end IN1 of the differential amplifier, the test point AIN2 and the switching switch SW2 are connected to the second input end IN2 of the differential amplifier, the test point AIN3 is connected to the first output end (i.e. the collector C of transistor Q1) of the differential amplifier, and the test point AIN4 is connected to the second output end (i.e. the lead-out point of test point AIN4) of the differential amplifier. The test point AIN1, the test point AIN2, the test point AIN3 and the test point AIN4 are respectively used to connect each signal channel of the oscilloscope. The power supply ends of the differential amplifier and the voltage stabilizing unit are respectively used to connect the power supply. The switching switch SW1 is used to select to access the first signal source, ground or the second input end IN2 of the differential amplifier. The switching switch SW2 is used to select to access the second signal source, ground or the first input end IN1 of the differential amplifier. The switching switch SW3 is used to connect the collector, base and emitter of the transistor Q1 in the differential pair tube to the multimeter respectively.

[0029] It can be understood that, as Figure 1 shown, the zero adjustment potentiometer PR is a potentiometer, and in the experimental demonstration process, the resistance value between the sliding contact and any two fixed terminals can be changed by adjusting the position of the sliding contact. In this embodiment, the zero adjustment potentiometer PR is introduced between the differential pair tubes, and the circuit structure remains simple while supporting efficient adjustment of circuit parameters, thereby improving the demonstration condition efficiency of the circuit.

[0030] The voltage stabilizing unit can adopt an existing voltage stabilizing circuit design or an improved voltage stabilizing circuit design. In the embodiment, the voltage stabilizing unit is used as a constant current source (or a current source load) of the differential amplifier. The beneficial effects of the design include: 1. The constant current source formed by the voltage stabilizing unit can keep the total current of the emitter of the differential pair constant, thereby greatly enhancing the ability to suppress common mode interference; 2. The influence of temperature on the current of the differential pair can be offset, thereby maintaining the stability of the circuit performance; 3. When the power supply voltage fluctuates, the constant current source can isolate the influence of the fluctuation on the current of the differential pair, thereby ensuring that the circuit can still work stably when the power supply changes. Therefore, the voltage stabilizing unit branch improves the performance of the differential amplifier from three dimensions of “suppressing common mode interference”, “stabilizing working point” and “anti-power fluctuation” by constructing a constant current source, thereby helping to improve the demonstration effect of the circuit experiment teaching from the deep functional principle of the circuit.

[0031] The switching switch SW1, the switching switch SW2 and the switching switch SW3 can all be multiple selection switchers. The switching of the corresponding signals, branches and power supplies can be directly realized by dialing the gear of the switch during the experiment demonstration, thereby directly facilitating the experiment demonstration operation. For example, the switching switch SW3 can be a three selection switcher. The three stationary contacts of the switching switch SW3 are respectively connected to the collector C, the base B and the emitter E of the transistor Q1 of the middle differential pair. The moving contact of the switching switch SW3 is connected to the multimeter. By dialing the three gears of the switching switch SW3, the collector C, the base B and the emitter E of the transistor Q1 are respectively connected to the multimeter, and the corresponding measurement can be performed. Figure 1

[0032] The differential amplification circuit demonstration board integrates the differential amplifier, the zero setting potentiometer, the voltage stabilizing unit and a plurality of switching switches on the same circuit substrate, integrates a plurality of test points at specific positions of the circuit, selects the connection of the external power supply, the signal source and the multimeter through the plurality of switching switches, supports the connection to the oscilloscope through the plurality of test points, and enables the teachers and students to directly operate the demonstration of the functional characteristics such as the static working point measurement, the zero setting, the common mode suppression (double-ended input, double-ended / single-ended output), the differential mode amplification (double-ended input, double-ended output), the single-ended input (double-ended / single-ended output) and the nonlinear distortion, thereby solving the technical problem that the functions and performance characteristics of the differential amplification circuit are not easy to demonstrate and enabling the functions and performance characteristics of the differential amplification circuit to be efficiently and flexibly demonstrated.

[0033] In one embodiment, as Figure 1 ​As shown, the voltage stabilizing unit includes transistor Q, resistor R5, voltage stabilizing tube ZD and resistor R6. The collector of transistor Q is connected to the sliding end of the zero setting potentiometer, one end of the emitter of transistor Q is connected to one end of resistor R5, the other end of resistor R5 and the anode of voltage stabilizing tube ZD are both used for connecting the negative end of the power supply, the base of transistor Q is connected to the cathode of voltage stabilizing tube ZD and one end of resistor R6 respectively, and the other end of resistor R6 is used for connecting the positive end of the power supply.

[0034] It can be understood that the embodiment provides a simplified and efficient voltage stabilizing unit structure design. The voltage stabilizing tube ZD and the transistor Q are used to keep the total current of the emitter of the differential pair transistor constant, and the resistor R5 and the resistor R6 are used to set the bias of the transistor Q and the current limiting of the voltage stabilizing tube ZD, so as to realize the stable control of the current and the voltage. The circuit structure of the demonstration board can be further ensured to be simple and efficient through the voltage stabilizing unit structure design, so as to further reduce the understanding difficulty of the teaching demonstration.

[0035] In one embodiment, as shown in Figure 1 The differential amplification circuit demonstration board further includes a switching switch SW4 and a power supply adapter (as shown by the "power supply" mark on the substrate) integrated on the substrate. The switching switch SW4 is connected to the power supply adapter, the power supply end of the differential amplifier and the power supply end of the voltage stabilizing unit respectively. The power supply adapter is used for connecting the power supply. The switching switch SW4 is used for switching the connection of the positive and negative 5-volt power supply or the positive and negative 12-volt power supply.

[0036] It can be understood that the switching switch SW4 and the power supply adapter can be directly integrated on the substrate in the embodiment, so that two external power supplies with different voltages can be connected to the circuit through one power supply adapter in the teaching demonstration process, and the corresponding power supply can be switched by dialing to different gears through the switching switch SW4. Finally, the teaching demonstration operation efficiency of the circuit demonstration board is further improved.

[0037] In one embodiment, as shown in Figure 1 The differential amplification circuit demonstration board further includes an oscilloscope adapter (as shown by the "oscilloscope" mark on the substrate) integrated on the substrate. The oscilloscope adapter is connected to the test points AIN1, AIN2, AIN3 and AIN4 respectively. The oscilloscope adapter is used for connecting the oscilloscope.

[0038] It can be understood that the oscilloscope adapter can be directly integrated on the substrate in the embodiment, so that the oscilloscope can be connected to the circuit in a plug-in manner through one oscilloscope adapter in the teaching demonstration process, and the signal waveform of the circuit can be efficiently and reliably demonstrated. Finally, the teaching demonstration operation efficiency of the circuit demonstration board is further improved.

[0039] In one embodiment, as shown in Figure 1As shown in the above, the differential amplification circuit demonstration board further includes a signal source adapter integrated on the substrate (as shown by the "signal source" mark on the substrate), which is connected with the switch SW1 and the switch SW2 respectively, and is used to connect the first signal source and the second signal source.

[0040] It can be understood that in the present embodiment, the signal source adapter (including the first signal source terminal S1 and the second signal source terminal S2) can also be integrated directly on the substrate, so that in the process of teaching demonstration, two different external signal sources can be conveniently connected to the circuit for signal input in a plug-in manner through one signal source adapter, and the corresponding signal source access of different circuit branches can be efficiently realized by switching the switch SW1 and the switch SW2 to different gears as needed, thereby further improving the teaching demonstration operation efficiency of the circuit demonstration board.

[0041] In one embodiment, as shown in the above, Figure 1 As shown in the above, the differential amplification circuit demonstration board further includes a multimeter adapter integrated on the substrate (as shown by the "multimeter" mark on the substrate), which is connected with the switch SW3, and is used to connect the multimeter.

[0042] It can be understood that in the present embodiment, the multimeter adapter can also be integrated directly on the substrate, so that in the process of teaching demonstration, the external multimeter can be efficiently and reliably connected in a plug-in manner through one multimeter adapter, and the direct detection of different electrodes of the circuit can be realized by cooperating with different gears (such as three gears corresponding to the base, the collector and the emitter) of the switch SW3, thereby further improving the teaching demonstration operation efficiency of the circuit demonstration board.

[0043] In one embodiment, the power adapter, the oscilloscope adapter, the signal source adapter and the multimeter adapter are all DuPont wire adapters.

[0044] It can be understood that in the present embodiment, the entire differential amplification circuit demonstration board can be connected with the pocket experiment platform directly by integrating four DuPont wire adapters: the power adapter, the oscilloscope adapter, the signal source adapter and the multimeter adapter on the substrate, and the demonstration circuit board can also be directly connected with the separate external power supply, the oscilloscope, the signal source and the multimeter respectively. The unified adapter type can reduce the difficulty of adaptation of different external platforms, thereby further improving the demonstration operation efficiency of the circuit.

[0045] In some embodiments, some demonstration application examples of the above differential amplification circuit demonstration board are also provided to further demonstrate its effect:

[0046] The aforementioned differential amplifier circuit demonstration board can be equipped with 4 DuPont wire adapters for connecting the demonstration board to the pocket experimental platform. The input and output configuration (recommended) includes power supply configuration, input configuration (signal source), and output configuration (oscilloscope). The power supply configuration should be consistent with the "VCC switch" on the demonstration board, that is: (1) when "VCC switch" is switched to 5V, the power supply is set to 5V; (2) when "VCC switch" is switched to 12V, the power supply is set to 12V.

[0047] The input configuration (signal source) includes common-mode input (e.g., the first and second signal sources both have a frequency of 5kHz, a peak-to-peak value of 50mVpp, a DC value of 0mV, and a phase of 0deg) and differential-mode input (e.g., the first signal source has a frequency of 5kHz, a peak-to-peak value of 50mVpp, a DC value of 0mV, and a phase of 0deg, and the second signal source has a frequency of 5kHz, a peak-to-peak value of 50mVpp, a DC value of 0mV, and a phase of 180deg).

[0048] Output configuration (oscilloscope), such as the oscilloscope's acquisition channel configuration and mathematical operation function configuration. When using the oscilloscope, disconnect the "multimeter" port on the demonstration board to avoid interference.

[0049] Demonstration instructions:

[0050] (1) Static operating point measurement: Switch the “multimeter voltage measurement” switch to “collector”, “base” and “emitter” respectively. The voltage of the three electrodes can be measured by the multimeter to determine the operating area.

[0051] (2) Zeroing: Open the corresponding channel of the oscilloscope (such as the configured channel 3 or 4), rotate the zeroing potentiometer PR, and observe the zeroing waveform; the oscilloscope displays the zeroing waveform as follows: Figure 2 As shown, the horizontal axis of the waveform represents time (microseconds), and the vertical axis represents the signal amplitude (millivolts). The coordinate axes of other waveforms in the following text have the same meaning.

[0052] (3) Common-mode suppression (dual-ended input, dual-ended / single-ended output): Turn on the first signal source, turn off the second signal source, switch the switch at the first input IN1 position to the first signal source terminal S1, and switch the switch at the second input IN2 position to the first input IN1; (or configure the first and second signal sources as common-mode input, switch the switch at the first input IN1 position to the first signal source terminal S1, and switch the switch at the second input IN2 position to the second signal source terminal S2) turn on the oscilloscope's acquisition channels (e.g., if channel 1 to channel 4 is configured); turn on the oscilloscope's mathematical operation function, subtract the measurement results of channel 1 from those of channel 2, and observe the input and output waveforms displayed on the oscilloscope. Figure 3The figure shows the suppression of common mode signal by the differential amplifier circuit. Channels 1 to 4 are four signal channels currently configured to be used as acquisition channels in the oscilloscope.

[0053] (4) Amplification of differential mode (double-ended input, double-ended output): configure the first signal source and the second signal source as differential mode input; turn the switch at the first input end IN1 to the first signal source terminal S1, and turn the switch at the second input end IN2 to the second signal source terminal S2; turn on the acquisition channels of the oscilloscope (for example, channels 1 to 4 are configured to be used); turn on the mathematical operation function of the oscilloscope, subtract the measurement results of channels 1 and 2, and observe the input and output waveforms displayed by the oscilloscope as shown in Figure 4 The figure shows the amplification of differential mode signal by the differential amplifier circuit.

[0054] (5) Single-ended input (double-ended / single-ended output): configure the first signal source and the second signal source as common mode input; turn the switch at the first input end IN1 to the first signal source terminal S1, and turn the switch at the second input end IN2 to GND (or turn the switch at the first input end IN1 to GND, and turn the switch at the second input end IN2 to the second signal source terminal S2); turn on the acquisition channels of the oscilloscope (for example, channels 1 to 4 are configured to be used); turn on the mathematical operation function of the oscilloscope, subtract the measurement results of channels 1 and 2, and observe the input and output waveforms displayed by the oscilloscope as shown in Figure 5 The figure shows the response of the differential amplifier circuit to single-ended input.

[0055] (6) Nonlinear distortion: by increasing the amplitude of the input signal, the effects of cutoff distortion and saturation distortion can be demonstrated, and the input and output waveforms displayed by the oscilloscope are as shown in Figure 6 The figure shows the response of the differential amplifier circuit to single-ended input.

[0056] In the above waveforms Figures 2 to 6 , the yellow waveform is the output of channel 1 of the oscilloscope, the blue waveform is the output of channel 2 of the oscilloscope, the purple waveform is the output of channel 3 of the oscilloscope, the green waveform is the output of channel 4 of the oscilloscope, and the pink waveform is the waveform obtained by subtracting the measurement results of channels 1 and 2 of the oscilloscope.

[0057] The circuit design of the differential amplifier circuit demonstration board fully demonstrates the advantages of one board with multiple uses and one board with full coverage.

[0058] It should be noted that in the specific circuit diagrams of each circuit part, if the pins in different circuit diagrams are marked with the same reference numerals, it means that the pins with the same reference numerals are connected.

[0059] The technical features of the above embodiments can be combined arbitrarily, and to make the description concise, all possible combinations of the technical features in the above embodiments are not described, but as long as the combinations of the technical features do not exist contradictory, they should be considered as the scope of the description.

[0060] The above embodiments only express several implementation manners of the utility model, the description is more specific and detailed, but it should not be understood as the limitation of the protection scope of the utility model. It should be pointed out that for ordinary skilled persons in the art, on the premise of not departing from the concept of the utility model, a number of modifications and improvements can be made, which all belong to the protection scope of the utility model.

Claims

1. A differential amplifier circuit demonstration board, characterized by, The differential amplifier, the zero setting potentiometer, the voltage stabilizing unit, the switching switch SW1, the switching switch SW2 and the switching switch SW3 are integrated on the substrate; The differential pair tubes in the differential amplifier are connected through the zero setting potentiometer, the sliding end of the zero setting potentiometer is connected to the voltage stabilizing unit, the test point AIN1 and the switching switch SW1 are both connected to the first input end of the differential amplifier, the test point AIN2 and the switching switch SW2 are connected to the second input end of the differential amplifier, the test point AIN3 is connected to the first output end of the differential amplifier, the test point AIN4 is connected to the second output end of the differential amplifier, the test point AIN1, the test point AIN2, the test point AIN3 and the test point AIN4 are respectively used for connecting the signal channels of the oscilloscope, and the power supply ends of the differential amplifier and the voltage stabilizing unit are respectively used for connecting the power supply; The switching switch SW1 is used for selecting to access the first signal source, the ground or the second input end of the differential amplifier, the switching switch SW2 is used for selecting to access the second signal source, the ground or the first input end of the differential amplifier, and the switching switch SW3 is used for connecting the collector, the base and the emitter of the transistor Q1 in the differential pair tubes to the multimeter respectively.

2. The differential amplification circuit demonstration board of claim 1, wherein, The voltage stabilizing unit comprises a transistor Q, a resistor R5, a voltage stabilizing tube ZD and a resistor R6; The collector of the transistor Q is connected to the sliding end of the zero setting potentiometer, the emitter of the transistor Q is connected to one end of the resistor R5, the other end of the resistor R5 and the anode of the voltage stabilizing tube ZD are both used for connecting the negative end of the power supply, the base of the transistor Q is connected to the cathode of the voltage stabilizing tube ZD and one end of the resistor R6 respectively, and the other end of the resistor R6 is used for connecting the positive end of the power supply.

3. The differential amplification circuit demonstration board of claim 2, wherein, The switching switch SW4 and the power supply adapter integrated on the substrate are further included, the switching switch SW4 is connected to the power supply adapter, the power supply ends of the differential amplifier and the power supply ends of the voltage stabilizing unit respectively, the power supply adapter is used for connecting the power supply, and the switching switch SW4 is used for switching the access of the positive and negative 5-volt power supply or the positive and negative 12-volt power supply.

4. The differential amplification circuit demonstration board of claim 2, wherein, The oscilloscope adapter integrated on the substrate is further included, the oscilloscope adapter is connected to the test point AIN1, the test point AIN2, the test point AIN3 and the test point AIN4 respectively, and the oscilloscope adapter is used for connecting the oscilloscope.

5. The differential amplification circuit demonstration board of claim 2, wherein, The signal source adapter integrated on the substrate is further included, the signal source adapter is connected to the switching switch SW1 and the switching switch SW2 respectively, and the signal source adapter is used for connecting the external first signal source and the second signal source.

6. The differential amplification circuit demonstration board of claim 2, wherein, The multimeter adapter integrated on the substrate is further included, the multimeter adapter is connected to the switching switch SW3, and the multimeter adapter is used for connecting the multimeter.

7. A differential amplification circuit demonstration board according to any one of claims 3 to 6, characterised in that, The power supply adapter, the oscilloscope adapter, the signal source adapter and the multimeter adapter are all Dupont line adapters.

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