In the evening of that day, Carl came to California Institute of Technology, and after getting the information needed to apply for a patent from Evan, he hurriedly left.

In order to relieve the anxiety of waiting, Evan found playing cards, stuck a layer of white paper on it, and drew PWH cards on it. In less than a day, he made two decks that could be played against. After trying to fight with Evan for several games, Rick became addicted to it and couldn't extricate himself.

Waiting around, Evanding's plastic parts were finally delivered on Thursday.

Magic7 company sent a special person to deliver it.

After getting the materials, Evan immediately threw down the cards and ignored them. He happened to have made most of the cards in the core series he remembered, and he was not interested in doing the remaining enrichment of the deck library and the numerical balance design work.

On Friday, Evan didn't go to class and stayed in the lab with Leiden all day.

Everything was ready, and the two men in white coats began to make point contact transistors.

The structure of the point-contact transistor looks simple, but it also tests personal hands-on ability when making it.

First, they have to lay a horizontal surface under the "典"-shaped plastic frame with conductive material gold foil, and then put a single germanium crystal on the gold foil;

Then, lay the gold foil on one corner of the triangle wedge and connect the spring to the side corresponding to the corner. In this step, both of them must be careful not to break the gold foil;

Next, fix the other end of the spring to the horizontal line above the "典" frame. In order to make the spring adjust up and down, screws are used;

Finally, press the wedge with gold foil on the surface of the germanium single crystal. Under the pressure, the gold foil on the corner will be broken. This step is very critical. The force applied to the wedge cannot be too large or large. It is necessary to ensure that the two sections of gold foil are close enough.

This point contact transistor was made in more than an hour after Evan and Leiden collaborated. This speed was faster than Evan originally expected.

Next is the test. If this is a successful transistor, when a small current is added to the gold foil on one side, the gold foil on the other side will be able to measure a larger current.

In the experiment, the former is defined as the emitter and the latter is defined as the collector.

The two of them turned around this "small" transistor several times and after confirming that there was no problem, they moved it to the laboratory bench. The measuring instrument and the power supply for experiments were placed on the laboratory bench, which could adjust the output voltage. After placing the transistor on the measurement circuit that had been prepared, the two officially started the test work.

Evan acts as a tester, and Leiden acts as a data recorder.

At the beginning of the experiment, Evan first gave the emitter a small voltage (Ve) and 0.1 volt, and then adjusted the emitter current (Ie) by adjusting the load resistance. The measured Ie was also very small at the beginning, below the milliampere order.

“The collector has no current (Ic) through!”

Leiden glanced at the ammeter and reported.

This result is normal.

After Leiden recorded the results, Evan began to increase Ie.

“0.5 mA…”

“Ic is zero.”

"Continue, Ie is 1 mA..."

“Ic is zero…”

Ie is added until it cannot be added again (the load resistance has been adjusted to the minimum), and Ic does not respond.

Evan and Leiden looked at each other and felt a bad premonition.

Evan proposes: "Add Ve..."

Leiden nodded and said, "I think how to add Ve directly to 0.5 volts?"

“OK!”

Evan twisted the power supply's adjustment knob, set the output voltage to 0.5 volts, the load resistance is re-added to maximum, and the test starts again.

“Ie, 0.4 mA…”

“Ic, zero.”

“Ie, 1 mA…”

“Ic, zero.”

Evan frowned, not adding Ie bit by bit, but added it to the maximum one at once.

“Ie, 3.6 mA…Ic, zero”

Seeing this result, Evan's expression became heavier.

However, even so, the test continues.

About half an hour later, after the scheduled test was over, Leiden sat in a chair next to the experiment bench with a gloomy face, holding the experiment record table in his hand, and his eyes were turning back and forth between the experimental data and the transistor on the experiment bench.

Evan spread his legs, supported his elbows on his thighs with his left and right hands, crossed his palms and ten fingers, leaned forward and lowered his upper body, and his fingertips pushed his chin from time to time, and his face looked meditative.

Obviously, this transistor failed.

Both of them were reviewing what went wrong.

It was already past twelve o'clock, but neither of them wanted to have lunch.

After a period of contemplation, Evan took the lead in breaking the silence and said, "Leedon, first of all, we need to have a consensus, that is, the theory I had previously proposed was correct..."

Leiden put down the record form, nodded at Evan, and said, "I agree!"

"Very good!" Evan straightened up, pointed to the transistor on the lab, and said, "Then, the problem will only be with it."

"The first possibility is the problem of germanium crystal material. According to Badin's paper, the purer the material, the better... Bell Labs may have been on guard against it."

Leiden said: "There is a possibility, but I think the possibility will be lower..."

"That's right!" Evan stood up suddenly, holding his hands on the edge of the laboratory bench, staring at the transistor intently and said, "The greater possibility is that we haven't done it well somewhere..."

Leiden stood beside Evan, hugged his arms and muttered, "Which place is it? Where..."

Suddenly, he stopped, and a flash of inspiration flashed in his mind. At almost the same time, Evan turned around.

The two looked at each other and said in unison: "Width!"

Seeing that the other party and he thought about it, the two looked at each other.

Evan said: "Yes, before making this transistor, I mentioned that the width between the two gold foil contacts was the key. Now it seems that I still took it lightly."

"Let's do it, let's take it apart and measure the width between the contacts?"

Just as Leiden was about to nod, his stomach suddenly started to roar.

Evan smiled and said, "Forget it, let's solve the stomach problem first!"

After having lunch as fast as possible, the two couldn't wait to dive into the laboratory.

After rough measurements, Evan found that the distance between the two sections of gold foil was above 0.5mm.

"This span is too long and must be reduced to below 0.25mm!"

Evan breathed a sigh of relief when he found out the reason.

However, now the problem is also here, how can we ensure that the width meets the requirements?

Reducing the strength of the wedge down while making is the easiest way to do it, but it takes a little luck.

Evan and Leiden decided to try it a few times first, and if it doesn't work, then talk about it.

Evan thinks that trying a few more times will always succeed, after all, there are already "precedents".

However, after one afternoon and one night, the two of them were wasted a lot of gold foil, but they still failed.

The two of them, dejected and looked like they looked "unfair", could only fight again another day.
Chapter completed!