Leisurely Traveler with Check-in System

The snow has stopped.

A layer of snow covered the branches of the trees, and the ground too was blanketed, making a creaking sound underfoot. The distant mountains were covered with snow, merging with the color of the sky, and despite the snow, it wasn’t as cold as imagined. The shores of Shelk Lake in the distance hadn’t frozen yet.

Today, Li Younan could finally go out to find suitable wood to make a crystal radio for himself.

To be honest, just thinking about it was quite thrilling. This step wouldn’t take too long; he went into the forest, found a piece of spruce wood of the right size, chopped it into a log, and brought it back for processing.

For the crystal radio to receive sufficiently clear sound, every step had to be done as well as conditions allowed.

The first priority was the antenna.

The roll of copper wire that Li Younan got from the production team was mainly for building the antenna.

He first used wood to build a support structure, then twisted the copper wire into a Yagi antenna, setting it up directly outside the house.

Truth be told, making a crystal radio in the wild has its disadvantages, such as being far from a signal transmission tower, but it also has a big advantage—almost no outdoor electromagnetic interference, unlike the overly harsh electromagnetic environment in the civilized world.

He set up the Yagi antenna, with the other end of the copper wire extending directly into the house.

Throughout this process, Li Younan did not forget to start video recording.

He excitedly spoke to the camera, ”Hey, everyone, today we’re going to make something really interesting. Remember when I asked for a roll of copper wire from the production team at the start?”

”Now I’ve made it into an antenna. Yes, today we’re going to make an apocalypse gadget—a radio that doesn’t need electricity. Some might ask, can a radio work without electricity? When I finish making it, everyone will understand.”

”Firstly, this is an antenna, and the role of the antenna is, of course, to receive signals.”

”But now the problem is that we can’t hear all the signals received by the antenna. On one hand, the signals from this antenna are too mixed; it can pick up various frequencies of AM broadcasts... maybe even broadcast programs? Who knows...”

”On the other hand, the antenna’s signal is too weak. How do we solve these problems? We need to use a resonant circuit.”

While explaining, Li Younan worked, finding a piece of wood branch, shaving it into a perfect cylindrical shape, and then winding it with the copper wire from the hand-cranked generator.

”This thing is called an inductor. How do we measure the size of this inductor? Under the same parameters, the more turns the coil has, the greater the inductance. So what does the inductor do? Its primary role is to generate an electric field when an alternating signal passes through it...”

Li Younan patiently explained the principles and steps of making a crystal radio to the audience outside the camera.

He knew very well that when the show aired, the production team would likely cut all this content out—after all, most viewers didn’t have the knowledge base to understand it.

But Li Younan still explained very thoroughly, without the slightest hint of perfunctoriness.

The reason for this, aside from having something to say because it was boring while making it, was also that he hoped to, through the airing of this program, influence children who love science, especially domestic teenagers, and inspire their interest in science and technology.

Planting a seed now might just grow into a towering tree someday.

With copper wire, theoretically, all other raw materials for making a crystal radio could be found in the wilderness.

Only copper wire would be quite difficult to hand-assemble in the wild, but it’s not completely impossible.

In some wild areas, if there are green stones, they are more likely to contain copper ore—copper oxide is green.

Copper can also be extracted through smelting, but it would be outrageously difficult to use this crude copper to make a crystal radio.

Li Younan told the audience outside the camera, ”Anyone who often encounters world-ending scenarios knows, when all communications are down, you must hold onto one belief—you’re not the only survivor.”

”So, connecting with the outside world becomes particularly important, and a crystal radio is something you can rely on when doomsday arrives and there’s no communication equipment.”

”In the city, you can find better and more convenient materials...”

While assembling, Li Younan used his woodworking skills to make a flat frame operating table for the crystal radio.

The core components mainly included the detector, tuning capacitor, and antenna ground wire.

The antenna and ground wire were already sorted; for the detector, Li Younan directly took apart the diode from the hand-cranked generator.

It must be said, the parts inside this hand-cranked generator perfectly matched the core components needed for a crystal radio.

A hand-cranked generator isn’t just a motor with enameled copper wire and a magnet; in modern society, you also need capacitors and batteries to charge electronic devices with it, at the same time.

Since charging electronic devices with a hand-crank generator must necessarily use direct current, it’s a fact that diodes, and even transistors, can be found inside a hand-crank generator.

However, if the hand-crank generator wasn’t available, Li Younan could also use the galena on a button as a detector.

The role of the detector is to achieve signal decoding, functioning to separate the audio signals from high-frequency radio signals received by the coil.

The core method is to find a material with unilateral conductivity, and naturally, the best thing is a diode.

Next, a tuning capacitor is also required.

In simple terms, the role of a tuning capacitor is to make the received electromagnetic waves resonate. After resonance, a specific frequency can be amplified from the chaotic frequencies, thereby filtering out sounds of other frequencies.

If the hand-crank generator wasn’t available, a tuning capacitor is also easy to make.

You could easily use two pieces of animal leather dried in the sun, or use buttons as the two poles of the capacitor, with an insulating layer in between to create it.

At Li Younan’s level, he could quickly adjust the capacitance roughly by changing the overlapping area of the two poles.

If worse comes to worst, you can directly remove the tuning capacitor; although you can’t tune, you can only receive strong stations, but it is also the simplest method.

However, with the parts provided by the hand-crank generator right now, Li Younan could make the best-performing tuning capacitor.

With these core components including the tuning capacitor, earth lead, coil, and detector, Li Younan quickly assembled the crystal radio on a wooden frame.

It must be said, with expertise in electrical, carpentry, and radio skills, the crystal radio assembled by Li Younan had achieved the aesthetic limit under existing conditions.

This crystal radio was not only very beautiful, but all features were nearly up to the standards of production in a modern civilized industrial system—of course, relying entirely on the wilderness conditions, such functionality effects couldn’t be achieved.

Li Younan looked at his masterpiece with satisfaction and recorded it with a camera: ”Now we have a crystal radio, but there’s still one crucial component left to make, which is the sound device.”

There are two ideas for sound devices: one is to directly use a high-impedance headphone to hear the weak signals in the crystal radio, and another thought is to address signal amplification and power supply issues. Without the parts from the hand-crank generator, Li Younan would try to make a high-impedance listening device with enameled wire, but in that case, the sound would be very weak, requiring you to be very close to hear it, so the experience wouldn’t be great.

So Li Younan didn’t even think twice and decided to use the second method, making a speaker that can produce sound by solving the signal amplification and power supply issues.

Inside the hand-crank generator, there is a small lithium battery that can be used as a power supply. The voltage of this lithium battery is 5 volts, it can be used directly without extra voltage reduction.

The generator also contains a coupling capacitor and power filter, which are sufficient to make a small speaker that can produce sound.

Li Younan could put his cowhide to use again—the cowhide was very useful as the diaphragm for this small speaker.

The making of the sound device was the highest difficulty factor in the entire crystal radio, requiring very solid electronics knowledge, and only someone like Li Younan, who is proficient in circuitry and radio skills and has strong hands-on ability, could shape it by hand in the wilderness.

As the finished product came closer, Li Younan’s excitement grew.

Apart from the few staff members who increasingly couldn’t communicate with the contestants, he couldn’t hear any external sound.

Finally, before it got dark, Li Younan completed the assembly of the crystal radio.

He placed the crystal radio on the bedside table, took a deep breath, and faced the screen saying, ”Now it’s time to witness a miracle.”

He placed the tuner on the washer, and immediately, a clear but chaotic radio signal sound came from the speaker.

At this moment, Li Younan’s breathing became a bit erratic, and then he gently moved the adjuster piston.

As the tuner slid across the washer, the radio signal sound changed accordingly.

Finally, at a certain position, he faintly heard the sound of music.

He fine-tuned it again, and the sound became clearer, the noise gradually reduced, and finally, at a certain point, melodious singing came out from the speaker—this was an old song, played by some radio station, ”Wonderful Tonight.”

Hearing this music sound, Li Younan’s nose twitched, almost shedding tears.

It had been too long without hearing the outside world’s sound.

He gently wiped the tears from the corners of his eyes, the little ewe looked at him with a puzzled look at this time.

In his happiness, Li Younan kicked the little ewe in the butt, then regretfully said, ”It’s such a pity, after all, you’re just an animal, you can’t feel the emotions I’m feeling right now. Wonderful Tonight... Damn it, it really is a wonderful night!”