The moment the whistle blew, the entire venue erupted with a cacophony of loud, chaotic metallic clashing.
The latches on dozens of black metal cases were snapped open simultaneously.
The bottom was lined with a solid piece of black anti-static foam.
Carved into the foam were several hollows, each cradling finely crafted, finished components.
There were four palm-sized miniature solar panels, their surfaces coated with polycrystalline silicon that glinted under the overhead lights.
There were two sets of miniature wind turbines with streamlined white plastic blades and what looked like very smooth central axles.
And there were several highly sensitive piezoelectric ceramic sheets, complete with metal leads and terminals.
At the next workbench, a few guys from another province’s team were already getting excited.
"Grab the solar panels!"
one of the guys shouted.
"The ceiling is full of these lights! The brightness is definitely enough. Let’s take out all four panels and connect them in series!"
"Get the turbine blades out too,"
another one said.
"I just saw an exhaust fan on that wall over there. We can build a rack later and aim it at the fan."
Many of the surrounding teams had a similar reaction.
The sounds of wires being yanked out, plastic bags being ripped open, and discussions about how to build supports all mingled together in the spacious venue.
The finished components in the top layer became the first choice for the vast majority of teams.
When it came to harvesting ambient energy, solar and wind were the most obvious routes.
At the Su Province Team’s workbench,
the metal case was also fully open.
When Wang Huashao saw the solar panels in the top layer, his hand was already reaching for them.
His fingers had just touched the blue edge of the outermost panel.
"Don’t take those yet."
Chen Zhuo’s voice sounded from the side.
His tone was calm and his voice wasn’t loud, but it was clear enough for everyone at the table to hear.
Wang Huashao’s hand froze in mid-air.
He turned his head, looking at Chen Zhuo with some confusion.
"What’s wrong, Captain? We’re not taking the solar panels? Look, everyone else is setting them up. The lights in here are so bright, isn’t solar power a given?"
Chen Zhuo wasn’t looking at the solar panels.
He pointed to a corner at the upper right of the workbench.
An inconspicuous, transparent, sealed plastic bag sat there.
It was only the size of his palm.
Inside the bag was an ordinary red light-emitting diode with two long, thin metal pins.
Next to it was a small white label.
On it was printed a line of small black text:
Rated working voltage 2.5V, working current 20mA.
Chen Zhuo pulled his hand back and looked at the dark blue panels in the top layer of the metal case.
"The lights on the ceiling are at least ten meters from the floor."
"The illuminance of the light decreases by the square of the distance. By the time it reaches the desktop, not many photons are left."
He looked at Zhou Kai.
"Under this kind of attenuated, diffused light, these miniature polycrystalline silicon panels won’t generate an open-circuit voltage of more than 0.5 volts, and the short-circuit current will be in the microampere range."
"It’s the same for the wind turbine blades. The exhaust fans and air conditioning in the venue are too far away. The faint breeze reaching us can’t even overcome the static friction of the rotor, so the speed will never get up."
Chen Zhuo looked at the problem displayed on the screen.
"The topic is ’Harvesting Weak Ambient Energy.’"
"We have an input of 0.5 volts, and we need to light up a high-brightness LED that has a threshold voltage of around 2V and is rated for 2.5V."
"There’s a voltage gap of at least 2 volts in between."
"Under the current light and wind conditions, the voltage produced by the items the committee placed on top can’t even cross the diode’s threshold."
"No matter how you connect them in series, the internal resistance will multiply, and in the end, you won’t even get any current out of them."
Chen Zhuo walked around the corner of the workbench to the front of the case.
His hand went straight past the top layer of expensive-looking components.
He pulled open the bottom-most layer of the metal case.
There was no neat anti-static foam, nor any exquisite pre-made modules.
There was just a pile of loose parts packed in ordinary, transparent, self-sealing bags.
They looked very cheap.
"Our job isn’t to compete on the absolute value of energy collected."
Chen Zhuo’s hands rummaged through the self-sealing bags.
"What we need is extreme voltage boosting. As long as the environment can give us 0.2 volts, we’ll boost it to 2.5 volts."
He pulled out several bags from the bottom layer.
And tossed them onto the wooden worktop.
A small spool of very thin enameled wire.
A green ferrite magnetic ring, only the size of a fingernail.
Two black, square-shaped thermoelectric cooling plates.
An ordinary NPN-type transistor.
A few color-band resistors with different resistance values.
"We’re building a self-oscillating boost circuit," Chen Zhuo said.
The others at the table looked at the loose components.
"Zhou Kai, get ready to calculate the optimal turns ratio for the high-frequency transformer."
Chen Zhuo began assigning tasks.
"He Gui, I’ll need you to wind the coil. The wire is very thin, so be careful."
"Wang Huashao, go get a breadboard and build the peripheral test circuit."
"Don’t worry about what the other teams are doing. For these four hours, we’re focusing only on this one system."
Chen Zhuo turned to Miao Shian, pointing to the pile of loose color-band resistors and the multimeter.
"Shian, you’re in charge of quality control and data. God knows what the actual parameters of the loose components from the committee are. Remeasure the actual values for all the resistors and transistors, and calibrate the error. When we build the circuit later, not a single component gets on the board without your sign-off."
The four guys immediately sprang into action.
Zhou Kai took some scratch paper and a black pen from his backpack, glanced at the permeability parameter marked on the ferrite ring, and hunched over the table to start writing out equations.
He Gui took the spool of enameled wire, drew a deep breath, and began to think about how to start the bifilar winding.
Wang Huashao found a white breadboard in the second layer of the toolbox and began inserting jumper wires and pins for testing.
Chen Zhuo stood by the table, running through the topology of the entire circuit in his mind.
Lin Yi stood at the very edge of the workbench.
She watched Zhou Kai fill the paper with formulas, watched He Gui carefully pinch the tiny magnetic ring, and watched Wang Huashao poke around on the breadboard.
She waited for a moment and realized Chen Zhuo hadn’t assigned her a task.
Lin Yi pulled over a tubular steel folding chair that someone else had left behind.
"Nothing for me to do?" She glanced at Chen Zhuo. "I’m going to go sit down for a bit, then."
Chen Zhuo turned his head and looked at her.
He reached out, picked up the spool of thin enameled wire from the table, and pulled off a length of it.
Then he rummaged through the bottom of the toolbox and found a small piece of fine-grit sandpaper used for polishing pins.
Chen Zhuo walked over to Lin Yi and handed her the length of wire and the sandpaper.
"You can sit."
Chen Zhuo gestured toward the chair.
"This wire has an enamel insulation coating. You need to use the sandpaper to scrape it clean from the ends of the wires we’ll be using."
"Apply even pressure. Don’t break the copper core inside, and don’t make any scratches that might affect conductivity."
"Keep scraping until we’ve used it all up."
Lin Yi looked down at the thin wire in her hand.
Then she looked at the piece of sandpaper, from which a few grains of sand were already flaking off.
She didn’t say anything, just took the items, walked to the chair, and sat down.
She began to scrape gently along the length of the wire.
Time ticked by, second by second.
The atmosphere in the venue was becoming polarized.
Many of the surrounding teams were feverishly building large contraptions.
Some people were using iron wire and plastic tubes to build a tall rack, mounting the four solar panels on it and adjusting the angle to face the overhead light source.
Others ran to the wall, trying to figure out how to channel the wind from the huge exhaust fan.
The sounds of voices and movement were everywhere.
But in front of Chen Zhuo’s team’s workbench, it was quiet.
There were no large structures on their tabletop.
Only a few wires, a few small components, and a piece of scratch paper filled with formulas.
He Gui was bent over, his face close to the table, pinching the magnetic ring in his hand as he wound the wire around it, loop by loop.
Zhou Kai’s pen never stopped moving.
Lin Yi sat in the corner, her head down, holding the same posture as she slowly scraped the enamel coating.
In this enormous workshop, filled with the clash of metal and a clamor of noise,
the six of them were gathered around their table, each focused on the task at hand.
There was no unnecessary conversation—only the occasional scratch of a pen on paper and the faint whisper of sandpaper against enameled wire.

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