Inviting people

After thinking for a while, Bai Zirui came to the Department of Radio Electronics of Yenching University and found Xu Chenghe, the director of the department. He said straightforwardly: "Hello, Director Xu! I am Bai Zirui, majoring in national economy in the Department of Economics. I would like to invite our wireless

Students from the electronics department, please help assemble the stereo radio."

Xu Chenghe said with a smile: "Classmate Bai Zirui, I know that you are a student of Dai Lao and the first top scorer in the college entrance examination after the college entrance examination was resumed in Beijing. I heard that you have recently taken leave to run a fast food business. Dai Lao and other students from the Department of Economics

Several professors also led students to conduct practical activities with you."

Bai Zirui told the truth: "Director Xu, my fast food business is on the right track, so I went south to Yangcheng to purchase goods and start trading these days."

Xu Chenghe glanced at him in surprise and said, "You can just do your business of reselling, why are you thinking about assembling radios?"

Bai Zirui said matter-of-factly: "When I do business, of course I make money and sell something. Nowadays, when you get married, you need 'three turns and one ring' for four major items, and one of them is a radio. The most profitable radio is naturally a stereo radio."

, so I wanted to ask students from the Department of Wireless Electronics to help assemble a stereo radio."

Xu Chenghe said: "Classmate Bai Zirui, you are quite honest, but students should race against time to study so that they can build the country's electronics industry after graduation, instead of being distracted by other unimportant things."

Bai Zirui retorted: "Director Xu's words are wrong. Students in the Department of Wireless Electronics always learn knowledge from textbooks in school. Now that the country is in dire straits, it is difficult to allocate funds for the Department of Electronics to build a laboratory.

In this way, students will only be able to talk on paper in class, but lack the ability to actually operate, and they will not be exposed to the latest cutting-edge technologies in the world. After graduation, students will only be nerds who talk about how to contribute to the national electronics industry.

Contribute to the construction of the industry?"

Xu Chenghe was enlightened by Bai Zirui's words. He said solemnly: "Classmate Bai Zirui, I asked students from the Department of Wireless Electronics to help you assemble a stereo radio. If you become a big business in the future, can you help us?"

Get the latest foreign electronics technology?"

Bai Zirui vowed: "Director Xu, don't worry! Now that the country has reformed and opened up, when I can get a business license in a while, I will set up a company to develop in Xiangjiang and I will definitely help the Department of Wireless Electronics obtain the latest foreign technology and information.

.

My classmates helped me assemble a stereo radio, and I will donate 20% of the turnover from the radio business to the Department of Wireless Electronics to establish a laboratory and set up scholarships to help students improve their lives."

Xu Chenghe said ecstatically: "Okay! Then I will arrange for the professor to lead the students to help you assemble the stereo radio."

After saying that, he took Bai Zirui to find a professor in the Department of Wireless Electronics named Xiang Haige, and told him that Bai Zirui asked his classmates to help assemble a stereo radio, which aroused Professor Xiang Haige's strong interest.

Because recently he was overcoming wireless communications and encountered radio frequency problems, and the working principle of FM stereo radio: the high-frequency signal received by the antenna passes through the input circuit and interacts with the local oscillation frequency of the radio (its frequency is a fixed intermediate frequency higher than the external high-frequency signal)

, China's intermediate frequency standard is 465KHZ) are sent together into the frequency conversion tube for mixing - frequency conversion.

The load loop (frequency selection) of the frequency conversion stage generates a new frequency, that is, the intermediate frequency generated by the difference frequency. The intermediate frequency only changes the frequency of the carrier, and the original audio envelope does not change. The intermediate frequency signal can be better amplified. The intermediate frequency

The signal is detected and high-frequency signals are filtered out. After low-amplification and power amplification, the speaker is pushed to produce sound.

This involved the issue of radio frequency, which was helpful for his research on the subject. Professor Xiang Haige immediately agreed and immediately led two of his best disciples to follow Bai Zirui with their tools to the house he rented in Zhongguancun.

Professor Xiang Haige saw the electronic components that Bai Zirui bought from Yangcheng to assemble the FM stereo radio. He stepped forward to check these components again and again. These components were basically inferior products from the radio factory.

, there are also a dozen regular products mixed in.

Xiang Haige knew that these were the components brought out of the factory by the workers of the radio factory. They used these components to exchange for some money and tickets to supplement their family income. Many workers are doing this now. As long as there are no problems on the surface, the radio

No one in the factory went back to investigate further.

Professor Xiang Haige is naturally no stranger to FM stereo radios. He showed his students how to disassemble several of them during class. After checking the quality of the electronic components, he and two students prepared to assemble the radio.

Bai Zirui saw Xiang Haige and two students preparing to assemble a radio. He asked tentatively: "Professor Xiang, the FM stereo radio I want to assemble is a 4-band radio like the Sanyo SANYO-MR-9600 radio."

Xiang Haige frowned slightly when he heard that Bai Zirui was going to assemble a 4-band FM stereo radio. In fact, in 1975, Magic City made the first four-band radio in Chinese history, and won the National Technology Award for two consecutive years.

Prizes.

But that radio used integrated circuits, and the output of integrated circuits in China at this time was still very low, so other manufacturers were determined to follow, but they often had to give up because they couldn't get key components.

There is nothing we can do about this. China's electronic technology has lagged far behind the West, especially in large-scale integrated circuits. There are really not many technicians who can figure out the principles except for scientific research institutes, and these technicians often have

Concentrated in several big cities such as Beijing and Shanghai, it is very difficult for ordinary radio factories to develop new products.

Xiang Haige had visited a scientific research institute in Beijing and naturally knew that the principle of the 4-band FM stereo radio involves integrated circuits, so he pondered for a while and said: "Classmate Bai Zirui, the four-band FM stereo radio involves integrated circuits.

, if it is assembled, the price may not be acceptable to ordinary people."

Bai Zirui smiled and said: "Professor Xiang, you are a radio expert on the technology of stereo FM broadcasting. As a professional, you must know better than me. I have assembled and repaired radios before, and I suddenly thought that we could make the circuit like this

design……"

Based on the circuit drawings seen by later generations, he introduced the integrated circuit reduction and optimization plan to Haig in detail, and casually drew the circuit drawings.

Xiang Haige suddenly became enlightened after listening to Bai Zirui's explanation, and his eyes lit up even more when he saw the circuit diagram he drew. He sincerely admired: "This design is really ingenious. How did you come up with this design, Bai Zirui?"

Designed?”

Bai Zirui said with a guilty conscience: "Professor Xiang, this is just my immature idea. I am just talking on paper. Whether it will work in the end depends on your practice."

Xiang Haige nodded and said: "It will definitely work. Let's assemble a radio according to this design idea and try it out." After he finished speaking, he led the two students to start.

Thanks to: Xiaoerlaijujiu, Shelley Lives Wonderfully, The Night Breeze is Cool, The Wind is Cool, The Dragon Boat Festival, 20190501090333925 and other book friends for their multiple recommendation votes.
Chapter completed!