"There's another way to do that, and that's to convert alternating current to direct current!"

In the workshop, in Mo Lingwei's laboratory, Li Zexuan put down the pen and paper in his hand and spoke.

When Mo Lingwei and Wang Ji heard this, they couldn't help but be shocked in their hearts, and Mo Lingwei said: "Mountain Chief, how can this alternating current be converted into direct current?" ”

Li Zexuan said with a smile: "Whether it is alternating current or direct current, they all belong to electricity, and of course they can be converted to each other!" With the rectifier circuit, the alternating current can be converted into direct current, and with the inverter circuit, it can be converted into direct current! However, a new electronic component is needed in the rectifier circuit - the rectifier diode, which has unidirectional conductivity and can only pass through the current in one direction, with it, we can build a rectifier circuit! ”

When Mo Lingwei heard this, she immediately became interested, and she hurriedly asked, "Mountain Chief, what should I do with this rectifier diode?" Can you teach me? ”

The first female professor of Yanhuang Academy, who is knowledgeable in the eyes of others, is like an ignorant student at the moment, frantically absorbing knowledge from Li Zexuan.

Li Zexuan pondered for a moment and said: "This rectifier diode can be divided into electronic diodes and crystal diodes according to different materials. Miss Mo, Mr. Wang, I will teach you how to make this electronic diode today, you have to promise me not to leak it, otherwise not only the workshop will suffer losses, but Datang will also suffer losses! ”

At the end, Li Zexuan solemnly instructed Mo Lingwei and Wang Ji.

Electronic diodes, also known as vacuum diodes, are widely used in voltage stabilization and rectifier circuits because of their unidirectional conductivity. Throughout the history of the development of integrated circuits of mankind, the invention of electronic diodes can be called the starting point of the human electronics industry, so Li Zexuan cannot be said not to be serious.

In the previous life, after the invention of the electron diode, the American inventor DeForrest cleverly added a grid between the diode filament and the plate pole, and achieved the world's first electronic triode. Since then, these electronic components, which are sealed in "small glass bottles", have been widely used in various electronic fields. Electronic products such as TVs, radios, and amplifiers are all inseparable from diodes and transistors!

But the defects of electronic diodes and electronic triodes are also obvious - high power consumption, high heat generation, large volume, and short life, so people are always looking for new electronic devices to replace it. It wasn't until the birth of the transistor and the advent of solid-state electronics that the electron tube was completely replaced!

In the 21st century, the diodes and transistors used by countries around the world are actually transistors, and of course, there is also a name, called semiconductor tubes, because they are made of semiconductor materials silicon or germanium. With Datang's current industrial base, firstly, purifying silicon or germanium is a problem, and secondly, the production of PN junction, the key structure in semiconductor diodes, is also a considerable problem.

The so-called PN junction is to use different doping processes to make P-type semiconductors and N-type semiconductors on the same semiconductor substrate through diffusion, and form a space charge region at their junction called PN junction, and PN junction has unidirectional conductivity. Among them, N-type semiconductors are silicon crystals (or germanium crystals) doped with a small amount of impurity phosphorus elements, and P-type semiconductors are silicon crystals (or germanium crystals) doped with a small amount of impurities of boron elements.

Li Zexuan didn't have boron on hand yet, so he temporarily gave up the plan to make crystal diodes!

"Don't worry, what the mountain chief said here today, Wang will never say half a sentence to outsiders, even if he is drunk!"

Wang Ji was the first to bow his hand, but the second half of the sentence made people a little laughable.

Anyway, although this old guy is an alcoholic, he doesn't talk nonsense when he's drunk, which is quite reassuring.

"Mountain Chief, I won't leak what you said, I... I vouch for my life! ”

Hearing what Li Zexuan and Wang Ji said was quite solemn, Mo Lingwei also became serious and said to Li Zexuan.

Li Zexuan nodded and said, "That's good!" Next, I will tell you how to make this electron diode! ”

As he spoke, Li Zexuan picked up the pen and paper again, drew sketches, and explained: "First of all, we sealed two metal sheets in the vacuum glass tube, of course, we can also use the method we used to make electric lamps to exhaust the oxygen in the glass tube, and there is no need for a complete vacuum. After that, we add alternating current to the anode plate, and a constant current in the same direction appears on the other plate! ”

Mo Lingwei was a little puzzled: "Mountain Chief, what is the principle of this?" ”

Li Zexuan thought for a while and explained: "You see, when the anode potential is higher than the cathode, the electrons emitted by the cathode move towards the anode under the action of the electric field to form an electron flow. When the cathode voltage is higher than that of the anode, the electric field force on the electrons pulls the electrons back to the cathode and cannot produce current, so the electron diode has unidirectional conductivity and can be used for circuit rectification! ”

In fact, this effect was called the "Edison effect" in a previous life.

In 1883, in order to find the best filament material for electric light bulbs, Edison placed a copper wire near the carbon filament inside the vacuum bulb in the hope of preventing the carbon filament from evaporating. Although he failed, he inadvertently discovered that the copper wire, which was not connected to the circuit, was receiving a weak current from the thermal electrons emitted by the carbon wire. Although Edison did not study this phenomenon carefully, he applied for a patent for the "Edison effect".

In 1896, when Fleming was working to improve the detector in the wireless telegraph receiver, he envisaged the use of the Edison effect for detection. When he encapsulated two metal pieces in a vacuum glass tube and added a high-frequency alternating voltage to the anode plate, the Edison effect appeared, and when the alternating current passed through the device, it was turned into direct current. Fleming called this tube with two electrodes a vacuum diode, which had both rectification and detection functions, and was the first electronic device in human history.

What Li Zexuan has to do now is this vacuum diode! Although he knows the principle, he is really not completely sure whether he can do it in the end.

"Mountain chief, I roughly understand! Overall, the structure of this electron diode is not complicated, although it takes a lot of work to do, but it is not completely impossible to do, and you let me try it a few times! ”

After listening to Li Zexuan's explanation, Mo Lingwei thought alone for a long time, and finally nodded.

Wang Ji also arched his hand and said: "Wang probably understands!" I will do my best to help Miss Mo make the electron diode! ”

The progress of Mo Lingwei's side is directly related to whether his electrolysis workshop can continue normally, and of course he is more concerned than anyone else!

Li Zexuan nodded and said, "So it's hard work for the two of you!" But in my opinion, DC generators and electronic diodes can be manufactured at the same time! Whichever is built first, it will be put into use first, and the electrolysis workshop can start earlier! ”

For the sake of insurance, Li Zexuan decided to be hard with both hands, and to grasp both hands!

"Yes! Mountain Chief! ”

The two of them gave up their hands.

Li Zexuan nodded with satisfaction, and said secretly in his heart: With diodes, the triode will not be far away, and many electrical appliances will be built by then, and Datang will soon be able to enter the electronic age!

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