Siheyuan: Starting from a fitter

Chapter 121 Multimeter ([-])

Li Guocheng saw the note left by Zhao Ting on the dinner table, which read a few words: There is rice in the pot.

Li Guocheng smiled and went to the kitchen to open the lid of the pot. Inside were his favorite stews and white-flour steamed buns. When he picked them with chopsticks, he found a few pieces of fatty meat.I picked a bite of food and tested the temperature. It was already cold.

After re-igniting the stove and heating up the meal, I happily finished the loving meal that I don't know if it is breakfast or dinner.

I wanted to boil water and take a hot bath, but after thinking about it, I haven't had a good bath in several days. I might as well wake up and go to the bathhouse to take a bath and rub my back. It would be so relaxing.

He took off his coat and pants, fell on the bed wearing a sweater and woolen pants, and soon fell asleep.

I woke up at noon and went to a joint canteen not far from the street. I ordered braised pork slices and two steamed buns with two noodles. I had a simple bite and didn't dare to eat too much to avoid performing a fountain while taking a bath.

Go home, grab your bed, change clothes and toiletries, and throw them into the secret place first.As you approach the bathhouse, take out a change of underwear and toiletries when no one is looking.Pay and park your bike.

Because he came early enough, there were not many people inside. After taking a shower, Li Guocheng went straight into the hottest pool. He looked at the elders next to him, made eye contact with each other, and whispered to each other: "Where did you come from? If you don’t transition in the low-temperature zone, you will go directly to the high-temperature pool, and the balls will be gone.”

With Li Guocheng's hearing, everything was in his ears, and he couldn't help but agree.

After more than two years of practice, quantitative changes have produced qualitative changes. After this year, my skin became a little itchy, and my skin occasionally felt tingling during practice.This is very similar to the characteristics of leather refining.

Li Guocheng now insists on practicing every day just as a habit. Because he can't feel any progress, he puts most of his energy into the steel rolling mill.Even if he found signs of skin refining, he didn't pay too much attention. There was always a voice in his heart reminding him that no matter how powerful he was, he couldn't stop the bullet.

I didn't pursue anything deliberately, I just used the inner breath according to the practice route every day. The inner breath didn't increase much, but I gradually found that the inner breath became more solid and more controllable.

Of course, the benefits are also very obvious: strong physical strength, not easy to fatigue, quick recovery, steady hands, sharp eyesight, and concentration.The power of telekinesis seems to be related to mental variation, but it doesn't make sense to say that it has nothing to do with the practice. The better the body, the more durable the power of telekinesis.

Yesterday, he carved the transistor by hand and felt very comfortable. His subtle telekinesis allowed him to control it freely.

Li Guocheng was thinking about the exercises while enjoying the hot water. If the environment didn't allow it, he would have wanted to lie in the pool and hum a few times.

After feeling thoroughly soaked, go find a bath master and perform some operations, and you will feel refreshed.

After changing his clothes, he rode back to the laboratory. In the past few days, he will eat and live in the laboratory.

Li Guocheng has been working night shifts these days, and everyone is used to it.I usually don't see him during the day, but today I found that he had arrived early.

Everyone else had arranged their work, but Yan Jiefang was left with nothing to do and felt quite panicked.Every day I try to find ways to get close to everyone and help out.Wu Liankui didn't know what Li Guocheng was thinking, so he didn't arrange the work.

Yan Jiefang was preparing to wait for Li Guocheng after getting off work today. Unexpectedly, he saw him before getting off work. He wanted to go up and ask about the upcoming work arrangements, but he didn't expect that someone was more anxious than him.

"Brother Li, help me, if you can't throw it to me, just leave it alone," Zhou Xiaojuan said rushing over.

"What's wrong? Don't worry, let's take a breath before talking." Li Guocheng saw the other person's chest rising and falling rapidly and quickly looked away.

"I found the substrate. Most of the ones we use are epoxy resin boards. Copper or aluminum are melted and covered on the surface of the substrate to form a circuit. I can't figure out how to photocopy the circuit you mentioned on it, let alone chemical engraving. It's gone." The little girl looked frustrated.

"Isn't it written in my notes?" Li Guocheng was a little confused.

"What you wrote above is all about masking, photoresist, development, etching and other processes. It seems clear, but how to connect it with the circuit board, I can't figure out." Looking at the frustrated little girl, Li Guocheng said: I couldn't help but laugh out loud.

After listening to the little girl's narration, it was obvious that Li Guocheng took the wrong note, and it was only the beginning of the note.

"Really? Let me tell you about it." Li Guocheng didn't dare to say that he took the wrong notebook, nor did he dare to take out the correct notebook again, otherwise he would be afraid if the little girl went crazy.

"Jie Cheng, you come too," Li Guocheng looked at Yan Jiecheng who was hesitant and called over together.

"I want to hear it too." Suddenly Zhang Zhijing ran in and saw that she had just been eavesdropping.

Before Li Guocheng agreed, she held Zhou Xiaojuan's arm and stood beside her. It was obvious that the relationship between the two was already familiar.

Yan Jiecheng stood honestly on the other side of Li Guocheng, obviously not daring to get too close to the two girls.

Li Guocheng didn't bother to pay attention to them.

Go to your drawing table, spread out a piece of white paper, pick up a pencil, and explain as you draw.

"Circuit board production consists of the following steps, please remember them:
First, make a thin enough copper sheet, about the same size as the epoxy resin board, and stick them together with glue. This is the substrate;
Second, apply photosensitive glue on the copper sheet, the thinner the better;

Third, prepare a mask with circuits engraved on it;
Fourth, use ultraviolet light to irradiate the photoresist through the mask for a few minutes. The irradiated area will harden and will not be corroded, and the rest will be washed away.In this way, traces of the circuit diagram are formed on the copper sheet.

Fifth, soak the resin board in the etching solution to corrode the copper that is not covered with the photosensitive agent, leaving behind the desired circuit;

Sixth, drilling, tinning;
Seventh, then, the single panel is successfully produced."

Although Li Guocheng's painting skills are not great, he can still understand it.

"What is a mask? How do ultraviolet rays occur? What is photoresist? What is etching solution?" Zhou Xiaojuan asked four questions in a row like a barrage of questions.

"How did I know? You need to figure this out and create it," Li Guocheng said roguely.

The three of them looked at each other, looking at Zhou Xiaojuan who was about to explode again, Li Guocheng quickly waved his hand to stop him.

"I'm in charge of the mask, and Yan Jiefang is in charge of the ultraviolet light source. You two ladies will take care of the photosensitive glue and etching solution, okay?"

Although Yan Jiefang was confused, he did not dare to object and nodded silently.

"I don't agree," the children objected in unison.

After looking at them, Li Guocheng thought to himself that in just a short time, Zhang Zhijing was led astray by Zhou Xiaojuan.

"Don't be anxious, tell me the reason," Li Guocheng asked deliberately and seriously.

Zhang Zhijing's eyes evaded and she didn't dare to speak.Zhou Xiaojuan is very familiar with Li Guocheng and is not afraid at all.

"Photoresist, etching solution, you think we can come up with it, what they are, I can't find out at all."

"What a ghost if we can find out!" Li Guocheng thought to himself.

"Photoresist, the basic material is resin. For photosensitive materials, you can refer to the composition of camera film. The etching solution is either acid or alkali. You can experiment more and learn more," Li Guocheng began to talk nonsense.

Li Guocheng believes that there is currently a blank in this area in China, and the West is also in its infancy, with no reference and can only rely on its own efforts.

"Zhang Zhijing, how is your collection of chemistry books?" Li Guocheng suddenly remembered the task assigned to her.

"I bought a total of 18 books and borrowed 5 from the library. I am studying." Zhang Zhijing obviously lacked confidence.

"You leave what you want to see and give me the rest first." Li Guocheng had no choice but to become a generalist.

Zhang Zhijing nodded.

Seeing the obviously unwilling people, Li Guocheng hurriedly announced that he was off work, otherwise there would be a risk of his secret being exposed.Now Li Guocheng has a better vision than them, and his understanding of specific materials science is exactly the same as theirs.

Zhou Xiaojuan, who was about to leave, suddenly turned around, startling Li Guocheng.

"Where are the voltmeters, the available resistors and capacitors, and the enameled wires of various wire sizes?" Zhou Xiaojuan pointed to the workbench next to her.

"I only borrowed the voltmeter for three days, and this is the only one in the technical department."

After Zhang Zhijing finished speaking, she deliberately rubbed her arms.

Li Guocheng was speechless when he looked at the voltmeter the size of a suitcase. He made up his mind that he must design a multimeter first, otherwise it would be too inconvenient to conduct experiments.

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(End of this chapter)