African Nationhood

Chapter 327 Radios and Electric Speakers

In early June 1895, Jinling Electric Power College.

Sun Ying, a communications major, leaned next to a wooden box and listened carefully. The sound coming from the earphones was very harsh.

But if you listen carefully, you can still clearly hear that this is a song. The lyrics are: Let us swing the oars and the boat will cut through the waves...

Sun Ying recorded in the experiment book: This type of (iron) diaphragm material is moderately difficult to process, but the sound reduction is poor, and the current sound is harsh, so the overall evaluation is not suitable.

Beside her was more than one wooden box for sound, and there was another wooden box.

This wooden box contains tubes and electronic components. This is the world's first tube detector radio.

The inventor of this radio detector was her teacher Mr. Tesla.

……

In order to facilitate the study of communication major students, the Electric Power College invested in the construction of a 20-meter-high "transmitting tower".

To say that the tower is a bit exaggerated is to say that it is just a transmitting antenna, but it was built on the third floor of the teaching building.

The transmitting tower plays songs on the gramophone every day. These songs can be used to cultivate students' sentiments and are also provided as experimental tools for students.

……

Jinling Electric Power College currently has only 3 majors and 120 students.

They have three majors and often take classes together.

As a result, Sun Ying's relationship with Wang Zhonghai and Jiang Wei has become more harmonious. They often discuss study problems together.

Teacher Tesla was particularly busy during this time. In addition to going to Europe to give lectures, he also had to apply for patents for the complicated invention projects he was working on.

When Mr. Tesla applied for a patent, it was very simple. Basically, he could apply for a patent with some manuscripts and explanatory text.

This makes the students envious, and Mr. Tesla also hopes that he can obtain a patent one day.

……

Another Hertz teacher in the college needs to recuperate from illness, and he spends most of his time in a nursing home.

In addition, Teacher Tesla was busy with business, so the company arranged for senior brother Wang Bo, who had studied in Europe in his early years, to serve as the academic director of the college.

Senior Brother Wang is a top student majoring in mathematics who returned from studying in Europe in his early years. He and Senior Sister Shi Na from Physics came together.

Senior Shi Na's research direction is more laboratory-oriented, while senior brother Wang Bo's research direction is more practical problems.

I heard that he had spent some time in the military department, but later found that he was not suitable there, so he came to the Electric Power College.

This college is more like a research institute. Once Teacher Tesla left, the teaching tasks here basically came to a standstill.

The person in charge of the electrical appliance laboratory and senior brother Wang Bo began to organize students to form interest groups.

Sun Ying, Wang Zhonghai and Jiang Wei established an interest research and development group.

Since Mr. Tesla left, students at the Electric Power College have received the research and development task of the electrical appliance laboratory - to study electric speakers.

The principle of the speaker is very complicated. The basic principle is that the energized conductor is forced in the magnetic field, and the changing current passes through the coil to produce a changing magnetic field, which causes the speaker's diaphragm to vibrate and produce sound.

The research task issued by the Electrical Appliance Laboratory is - "Dynamic Speaker".

The electrical appliance laboratory has distributed the principle materials needed for research and development to students. In the learning materials, the electrical appliance laboratory has determined the composition of a "moving coil speaker".

It is composed of three parts: vibration system, magnetic circuit system and auxiliary system.

Since there were many students, Senior Brother Wang Bo divided the students into three parts, corresponding to the three parts of the speakers.

The group of Sun Ying, Wang Zhonghai and Jiang Wei was assigned to the vibration system research group. This research group has the busiest work because they need to study various materials and their advantages and disadvantages.

Each research team is required to have complete experimental records and material analysis.

After many students' research, they went through many experiments and tried hundreds of materials.

The following materials were finally determined:

Paper box: The cost of paper box is low and the price-performance ratio is the highest. It is also the diaphragm material that students in this research group tend to use most.

Ceramic: The subwoofer effect is better, others are average, and the price/performance ratio is average.

Wool carton: Made by mixing wool into paper pulp, the bass effect is not good.

Metal: Too expensive to process and impractical.

Wood: The sound is warm, more suitable for listening to human voices or classical music, and the processing cost is slightly higher, second only to paper boxes.

……

But Sun Ying was inspired by the wool carton and proposed to try adding other materials to the carton, perhaps the diaphragm effect would be better.

But other students felt that for now, it would be better to make the speaker successfully first and then talk about improvements.

The students immersed themselves in research and finally decided to use paper boxes and wooden boxes as the final diaphragm material options.

Now that the vibration system is ready and the difficulty of the magnetic circuit system and auxiliary system is minimal, the best assembly ratio can be tested with a little experimentation.

……

On the 5th in late May, students from the school's three majors gathered in the large lecture theater to try the final assembly experiment.

As the academic director, Wang Bo volunteered to assemble the speakers.

For comparison, two speakers need to be assembled, a cardboard box and a wooden box.

After the dust cover, diaphragm (paper cone or wooden cone), frame, spring coil, voice coil... are assembled and connected one after another, an original coil-type speaker is completely assembled.

The next step is to turn on the power and input the audio signal.

Wang Bo first plugged the audio connector of the cardboard speaker into the radio. Since the radio was not powered on, everyone present heard the buzzing sound of electricity.

But no one was disgusted with the sizzling sound of electricity. On the contrary, they were all used to it.

Wang Bo pressed the switch on the radio. As the switch was turned on, the sizzling sound of the current in the carton speaker disappeared and turned directly into a melodious song: "We live in the field of hope..."

Finally succeeded, everyone cheered, everyone was so happy.

This was the first time for the students to experience the taste and joy of success. Many of them shed tears of excitement, and more of them felt a sense of pride from the bottom of their hearts.

Wang Bo waited for a while and found that everyone's excitement had subsided. Then he announced loudly: "Everyone, be quiet. Let's evaluate the sound quality of the speakers."

Everyone listened for a while and felt that the sound quality of the carton speakers was very good in all aspects, and the high and low sounds were restored well.

After everyone commented, they connected the audio connector of the wooden box speaker again.

The song just now continues: "Our future is in the field of hope..."

Everyone continued to comment and felt that the diaphragms of the two materials were not much different, but in terms of overall cost performance, the paper box was cheaper and more perfect.

So the students decided to use cardboard as the final diaphragm material for the coil speaker, and applied for a patent for this!
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  (End of this chapter)