Differential amplifier

Add a differential amplifier, or use transformer coupling. In the past, there were some phase-shifting circuits, which can only be used for fixed frequencies. If there is no grounding, use two resistors in series and connect to the ground in the middle.

Rectification requirements:

First of all, immediately cancel all kinds of non-reusable promotional banners in the school. The superiors are checking the actual teaching level. They will know you when they see these disposable promotional materials. Squandering social resources has no practical significance for improving the quality of your teaching. Schools that rely mainly on state investment must pay special attention to correcting these wrong behaviors. Private schools that are too extravagant and wasteful will also be condemned by the public.

Huge inkjet printing of full-width slogans on the exterior walls of large buildings, banners hanging all over campus roads, large-area inkjet printing of publicity boards inside various colleges and grassroots teaching departments, and relevant information for each person. There is no direct and inevitable connection between printed matter and teaching quality. Isn’t it heartbreaking to see such a large-scale squandering of social resources?

The nozzle of this printer has not yet been domestically produced.

It cost 400,000 yuan to decorate a grassroots teaching institution of several hundred square meters. Repeated revisions added another 200,000 yuan to the cost. A 5-meter by 3-meter institution introduction plaque was built, which cost 10,000 yuan. Yuan, in order to welcome the review, it cost more than 10,000 yuan to start over. Who will pay for this expense?

Promote various reusable and rewriteable propaganda methods. Electronic newspapers are innovative display technologies that should be practical and report engineering capabilities to the party and the people.

Electronic display screens are mature technology and should not be purchased from the market. Each school should assemble and write programs by itself, and be completed by students themselves. All drawings, programs, etc., are archived in the school. Students can access it for free, providing a platform for future maintenance.

Vigorously compress, reduce, and replace paper non-rewritable hard copy teaching and research files to protect the environment, save expenses, reduce management staffing, and effectively use the teaching building area.

Modern digital photography equipment is cheap and has complete text recognition software. It should be used first and the use of traditional photocopiers should be reduced. In particular, the price of A3 format copying is too high and is higher than the unit-to-area price ratio of A4 format. It is 10 times that of the Internet, and students and teachers are not allowed to search at will and have limited value. Is it worth spending such a high cost to build for evaluation?

Establish a mass storage hard drive system and encourage review experts to access various relevant materials remotely. The modern access method does not require reception staff and is not noticed by the inspected unit. The amount of access is large and can truly reflect the actual level. , do not interfere with the school's normal teaching and scientific research activities, do not mobilize crowds, do not require police cars to clear the way, block roads, and oppose inspections based on superficial inspections.

Experts are encouraged to check the live classroom teaching through Internet videos, and they can suddenly ask questions to catch the unit being inspected off guard.

For the damaged parts of the mesh bag behind the seat of the vehicle receiving experts, it is necessary to darn and knit to repair it.

I introduced high-frequency power amplifier teaching materials and experimental equipment from ****. My experience is that during my undergraduate studies, I tried several experimental classes, but it was difficult to produce a decent output. As soon as the output waveform comes out, the 3DG12 medium power tube will be burned out.

So, during the Cultural Revolution, *** successfully imitated tube radio stations based on foreign lines, ***. And ***’s experience is that in the tube high-frequency amplifier, even if the tube’s own power consumption is large and the nickel plate of the screen is burned red (commonly known as the screen red), the operation is still normal. *** was specialized in this at that time; Solid high-frequency amplifiers - transistor and semiconductor high-frequency power amplifiers, have very low efficiency under the condition that the power tube has a large amount of power, and the power tube will burn out inexplicably.

Even domestic military radio stations that use foreign lines and imported cermet high-frequency power tubes have similar problems.

Existing domestic and foreign textbooks and professional books do not have specific solutions, and the relevant content is the same. Nowadays, from security walkie-talkies to people's mobile phones, as well as the hotly-hyped wireless tag high-frequency read-write cards and military communication radio stations, the radio frequency power chips are all imported, and their theory and process know-how are not told to you.

A variety of semiconductor high-frequency power amplifier teaching devices designed and produced by me have been used in actual teaching practice for students. The device (its principle and design and debugging methods have not been introduced) have completely solved the above problems. Difficulties.

Because I have been strictly prohibited from using computers since *** years, I cannot turn these handwritten materials into electronic documents and make them public (the computer I am using now is personal). The high-frequency power amplifier teaching device designed and produced by myself, in order to be intuitive and prevent students from damaging the magnetic core when adjusting, try not to use closed coils and mostly use ceramic skeletons. The ceramic skeleton manufacturer: the former No. 4 Machinery Department (Radio Industry) in Jingdezhen, Jiangxi Department) 999 Factory, 897 Factory. For more than 1,000 to 2,000 pieces, the volume of the packaging container is 40 cm x 40 cm x 80 cm. These ceramic skeletons were ordered to be destroyed by the police. The remaining parts were destroyed by the police, and their direct economic value was The amount of *** is exceeded.

The core significance of my above work is that there are various precise testing methods, and the prescribed steps can be used to test and adjust various parameters and working conditions of the circuit using ordinary instruments, all in an orderly manner. , measurable, with graphics for comparison, but the popular saying that the distribution parameters of high-frequency circuits are complex and that the performance of high-frequency circuits depends on the structural shape is a reflection of the lack of real understanding.

The current popular circuit simulation software and integrated circuit design software cannot truly reflect the working status of the actual circuit, especially simulation under high-frequency and high-speed conditions. Correct circuit testing and adjustment basis are required. Only by changing the integrated circuit layout and semiconductor process can the best radio frequency integrated circuit be produced.

I hope someone can turn these handwritten materials into electronic documents and make them public for free.

In the radio frequency identification topic in the 2007 National College Student Electronic Design Competition, the contestants guided by me used wireless transmitting and receiving circuits of discrete components; while the contestants guided by *** nearby, They all used imported wireless modules and were completely wiped out.

When I was working at ***, I independently designed electromechanical products and sold them nationwide. My colleagues at the time knew that I could explain the basis for a design from many aspects, especially why it was done this way. , specific details, strong language expression skills in engineering technology, rigorous conception, precise handcraftsmanship, and ***.

More than 20 years ago, I broke the teaching method of teaching by teaching. Instead, students randomly asked questions and then worked together to solve them. Because I usually did not have the conditions for laboratory work, I let the students ask questions randomly. I will give a comprehensive answer.

When students in the *** department are taking experimental classes and doing graduation thesis, they like to answer questions on the spot. They can solve problems immediately. Most of the questions that they are not prepared for can be solved with The speed of rapid fire, accurate answers, this kind of responsible attitude towards education, and unique ability aroused ****. The exquisite teaching device I made at my own expense is given to me for free, ***.

For example, when **** was doing his undergraduate experiments, he always burned transistors, and other **** made fun of him and humiliated him for being incompetent. When he passed by, he gave verbal instructions to the two students and found out on the spot. The reason is that students are the ones who did it; and the circuits for the experiment were selected and downloaded from the Internet. I did not know it in advance, but their circuit construction was error-free. The problem lies in their understanding of the circuit and debugging skills. Books There is no relevant content online.

This is the ability to accurately grasp and make students enlightened (tí hú guàn dǐng) and enlightened, so that they have a thorough understanding of the class content and a high level of understanding, even if it is an explanation of a basic concept, It will make you feel eye-opening and enlightened.

Now, just as far as *** is concerned, no one has the most basic three-stage tube circuit design ability, and no one has it in history; for laymen, it is mistaken for Exaggeration is untrue, but for those who are truly capable, these are no more than 10 small components, which can be used in low noise, low power consumption, switching state, small current switch, high current switch, high speed switch, low speed switch, high speed switch, etc. Frequency small signal, high frequency, high efficiency and high power, high power supply voltage, low power supply voltage, AC coupling, DC multi-level coupling, composite passive logic operation, integral blocking processing, differential processing skills, transient response, extreme temperature environment, frequency Domain characteristics, high reliability, etc., its design and debugging skills are quite rich, and they are also the foundation of the foundation. There are no public textbooks. Those who talk about how many dB the circuit they designed are actually related to gain and noise level, which are related to many trade-offs.

I am good at this. When students ask questions, my answers will be eloquent, eloquent, and exhausting, which was a rarity in that era. In ***

In view of the fundamental interests of the country, from the beginning of *** to ***, I have been entering student dormitories and lingering in laboratories for a long time and frequently to provide free tutoring to students. For example, you can investigate with ***. His experience is that before graduation, he really realized that he did not have the ability to solve practical problems. He was looking forward to having relevant books, but he could not find them online or in the library. It was stipulated that political questions could not be asked except for pure mathematics questions. I spent several months answering most of the questions he asked on the side of the road and in the student dormitory, and wrote specific instructions in a book on the spot.

To give another example, ***, when he was doing the challenge cup experiment, he couldn't ***. When he was about to give up, during the one-month holiday that year, I basically spent every morning and He provided guidance three times in the afternoon and evening. He achieved the expected goals without actually doing the actual operation himself. When my salary was 600 yuan, I also gave him questions and provided hardware to prompt him to complete the application of image processing. In the background of ****, I guided him to write patent application documents, and I funded the application for relevant invention patents. , has now entered the substantive review stage. Due to his minor writing errors, I made corrections according to the reviewer's request.

From *** to ***, I have been working without ***, overcoming insurmountable human obstacles, working silently, working seriously and responsibly, being the most down-to-earth, and having the most endurance. Well, my spirit has not been destroyed. I am stubborn, tenacious, and perseverant. I have purchased basic maintenance equipment for a long time. This is a manifestation of my loyalty to education.

Let me give you a few examples; I have examined The situation of various schools using professional experimental equipment produced by Japan has been generally not good. While making hardware modifications, I also guided the communication laboratory experimenter of *** University and demonstrated the correct waveform synchronization method on site. In fact, the same is true for basic experiments on digital circuits. Only by modifying the oscilloscope yourself or making your own oscilloscope can the effect of waveform synchronization be improved.

For ordinary digital circuit and logic circuit experiments, the level amplitude can basically directly deflect the cathode ray tube without amplification. A self-made teaching device should be used together with an oscilloscope.

The practical experience of digital circuit teaching, especially the experience of modern communication teaching, is that the observation and synchronization operation of the eye diagram must be supported by independently designed hardware synchronization circuits.

For frame synchronization signals, the synchronization of analog modulation and digital modulation of various frames is its specific embodiment.

The synchronization effect of the modulation process and the synchronization effect of the demodulation process in modern communication directly affects students' perceptual understanding of the principles of modern communication; and the phase, delay and channel between modulation and demodulation Conditions, etc. are an uncertain parameter. To accurately display the logical relationship between each other under synchronized conditions at the same time, you have to design and manufacture it yourself. Currently, there are no ready-made products that can be directly used, right?

Moreover, students must be provided with all design information in electronic format, debugging experience, component data, assembly drawings, waveform diagrams, procurement, processing locations and methods, processes, and prices, so that students can outperform others. Blue provides the platform.

A teaching method is that the values ??of the main components of the circuit can be changed independently and linearly, instead of using the mouse to click and pull. For example, in the exam, you need to be able to calculate relevant values ????according to the predicted direction, and use formula calculations to change the shape of the eye diagram and verify it. The textbooks of the Massachusetts Institute of Technology in the United States are all made public on the Internet. If you pass the exam just by using it, you are a skilled expert in system integration, not a master who starts from the basics to challenge them.

One way to test the quality of teachers' teaching is to use the current textbooks to give test questions outside the classroom and laboratory. You can tell us the maximum and minimum value ranges of this component, as well as the calculations. in accordance with?

A common understanding at home and abroad is that in world-leading research, it is necessary to have unique and top-notch instruments and equipment manufactured by ourselves; it is impossible to rely on existing commercial instruments on the market. To distance ourselves from competitors. Behind the scientific and technological level of advanced countries is the support of advanced experimental equipment.

Nowadays, most teachers in Chinese universities do not have the ability to manufacture instruments that are better than those on the market. Once they submit their plans to purchase instruments, suppliers from all walks of life flock to them. It feels like being worshiped by others. It's cool, while being bossy, arrogant, and pretending to be powerful, there is also ***.

No matter what academic qualifications teachers come to teach, they purchase experimental equipment from the market and copy the teaching materials provided by the suppliers as handouts.

One criterion for undergraduate evaluation is the self-made rate of teaching instruments, the design drawings and working principles of teaching instruments, the completeness and openness of test data, the technological advancement relative to existing commercial instruments, and the quality of teaching. Intuitiveness. The self-made instrument is reliable, maintainable, detectable and guaranteed.

An assessment standard for teachers and laboratory personnel is the comprehensive logistics ability to maintain the laboratory's water supply, drainage, power supply, furniture, doors, windows, lighting, and locks by themselves. Nowadays, teachers call maintenance workers even for trivial matters, which consumes a lot of social resources. If you can't do this little thing, how can you talk about designing and making teaching instruments? Do I need an electrician's certificate to replace a light bulb? It’s easy to just take the certificate exam, right? It's quite easy to do multiple things with one specialty.

China’s education must always serve proletarian politics, be integrated with productive labor, center on political and economic construction, and center on the country’s fundamental interests.

Here are a few minor rectification tasks proposed:

The bases of various detachable roadblocks on campus should be changed to built-in, all-stainless steel structures. For example, there are stainless steel internal expansion screw standard parts that can be used. Now that artificial diamond drill sleeves have been popularized and standardized, it is not difficult to design and produce such locks. Over the years, the base of the detachable barricades on campus has been higher than the ground and made of carbon steel with insufficient strength. After being crushed and dismantled by motor vehicles, it has been repeatedly repaired. The appearance is crooked and rusty. The cost has long exceeded that of all stainless steel. Structure, the ordinary expansion screws used to lay the ground have a short life, low strength and cannot be reused.

Some bases are hollow. Don’t they break once children’s feet, pets’ embroidered legs, and women’s high heels step into them?

*** can test the loyalty of the Ministry of Education to the motherland

***’s **** is frequently coated with lead-containing paint, which pollutes the campus environment and requires re- design.

Computers owned by colleges and universities are state property and cannot be specially allocated to contract workers to play games; the indoors in teaching buildings are teaching places and cannot be provided to contract workers for free and used to store their personal collections that can be sold. Recycling materials; contract workers who are not members of the campus police force cannot be allowed to stay in the teaching building, especially if they live together, especially if the interior is messy and the curtains are slovenly. How is it inappropriate in a higher education institution? The collection and processing of scrapped office supplies, paper and other salable materials in teaching and scientific research buildings should be contracted by current students. The campus police team should manage the entry and exit of recyclable materials in each building and cannot be illegally occupied by individuals; documents of each teaching department Mailing and receiving and office cleaning are handled by personnel within the department. This is their own job. Indeed, because of the shortage of manpower, it should be contracted by students and retired personnel. A large number of contract workers are recruited, which is a manifestation of corruption.

Contract workers who stayed in the building cooked food in the power distribution room, summoned rats, entered the power distribution cabinet, caused an explosion, and interrupted the power supply to the entire building.

The impact noise emitted by the door closers in family areas and teaching areas of various universities is now loud enough. Senior scholars who often travel abroad with public funds have turned a blind eye. This high academic status in the field of control and manufacturing is reflected in There?

Dozens of graduate students have graduated with wireless tags as their graduation thesis topic, and the cumulative number is about to exceed 50. So, for the management of motor vehicles and bicycles entering and exiting the campus, automatic charging for parking on campus can be Use appropriate equipment? This can only be reflected by the application of self-designed thick film circuits. There is no size requirement here. There is really no need to spend 3 million yuan to build an iron fence.

When visiting abroad, receiving domestic leaders, foreign dignitaries, and domestic and foreign scholars, the way to show your strength should not be papers, certificates, and purchased experimental instruments; instead of giving away various handicrafts and monographs, you should use independently produced materials. It is an innovative device with small size, precise structure, design research, and no precedent in the world. It is reflected through vivid demonstrations

It often wins the first prize in domestic and foreign college student competitions. This is an achievement. The following examples It is a system integration of purchasing standard market standard parts, using one-dimensional barcodes to print and identify outstanding works of undergraduate evaluation as an innovation laboratory, attracting ×××× experts to take turns to visit, and as ××× promotion, then the previous results are all worthwhile Doubted.

Introducing visiting professors and hiring scholars with international status and influence is easy if you have money. However, the working conditions require you to import large, precise, and state-of-the-art instruments and support them with full-time personnel. Such a master We are not lacking. What is the value-added benefit generated by other people's high-tech achievements?

Spending a lot of money to hire retired foreign dignitaries and Nobel laureates. The introductions are all in diplomatic terms. They use specialized companies to arrange global business activities. What they say is in the past tense and can be specific. Guide you to unparalleled global innovation?

The masters China needs are people like Yuan Longping who work hard at the grassroots level. As the same person, they can improve the technical indicators of mass spectrometers, repair inertial instruments and equipment, and personally operate from traditional machine tools to CNC. The equipment of the machining center is used to complete gas shielded welding,

Using domestic metal materials, domestic components, and domestic equipment to create internationally leading devices and publicly introducing every detail is what China needs most; technology, engineering, business, The "fast food" of management and the pursuit of immediate economic and academic achievements are the latest in time, and they are the daily and necessary basic content of life for the vast majority of Chinese people. Education is the hoop of China's bucket and the basic material for puzzle pieces, and primary and secondary schools and colleges and universities are the only areas that start from the basics.

In Mao Zedong’s era, he opposed closed doors and should be combined with application, which still has its progressive significance today. While consuming a lot of national resources to write papers among imported equipment, imported reagents, and documents from developed countries, the above minimum requirements should also be fulfilled in basic education.

China’s current system is correct, ××××. In fact, there is a considerable potential surge from overseas hostile forces. Without a firm patriotic belief, a rigorous scientific attitude, and no principle, the result of that kind of ××× will inevitably destroy the foundation of China.

While the whole society advocates wealth and publicizes the pursuit of wealth, in an environment where popular science books and vocational education are popularized, there should be substantial, open and free detailed introductions to the details of teaching and engineering.

Hiring foreign teachers and teaching students who have obtained certificates from foreign standard systems is a good work achievement; can't we compile new global standards and lead foreign production of products that adopt this standard?

Crack down on technological innovation ××××.

The cheap, fast-growing trees that were planted on campus in the past are now too big to hold. Because they are so brittle, their branches break and fall from time to time, which is quite scary. To safely cut down trees with such a perimeter next to buildings and sidewalks, it would cost 2,000 yuan a day to rent a crane, and another 1,000 yuan a day to hire a professional and rent a chain saw.

This kind of tree is of poor species, poorly maintained, and has a low survival rate. It can be pushed back to the beginning; but educating people cannot do this. The fire is not enough when they first receive education. For most people, In other words, no matter how much extra lessons you take, you can’t improve. After recruiting people, they cannot be fired easily.

Those products made of imported chips, military telemetry vehicles made of low-end commercial surveillance cameras, military combination locks, and laser communication devices made of industrial optical equipment, colleges and universities are not making these ordinary products. It also recruits a large number of people from society to work in the teaching building and open companies outside the school. Radio transmissions have no survivability on a modern battlefield, and even FM radio stations are viable targets. In high-altitude colleges and universities, it is a place where spread spectrum transmission and reception are started from the basics, and mobile state tracking and locking laser transmission is performed.