Chapter 127: Blueprints and Margins

The tip of the pencil scratched across the paper with a fine, even rustle.

Lin Chen did not put pen to paper immediately. He stared at the blueprint, his gaze moving slowly along the dense wiring traces. Transistors, coupling capacitors, feedback network, load resistors. The symbols were marked in an old Russian notation, the parameter units were mixed together, and the power-supply polarity had been drawn rather casually. This was not a standard textbook problem from high school, but a variant of an intermediate-frequency amplifier circuit from an old superheterodyne radio—and its key grounding points had been deliberately omitted.

He closed his eyes.

The internal structure of that Red Lantern-brand radio in the repair shop unfolded layer by layer in his mind. Loose solder joints. Replaced germanium transistors. Bias voltages measured again and again with a multimeter. He opened his eyes and drew the first node on his scratch paper. Base bias. Emitter AC ground. Collector load. The lines were straight, without unnecessary ornament. He did not need to produce a beautiful schematic; he only needed a closed loop of logic.

“Basis for parameter selection.”

The chief examiner’s voice sounded in the quiet room, measured and steady.

Lin Chen paused his pen. He pointed to the coupling capacitor on the blueprint. “This is marked as 0.01 microfarads. In practice, the intermediate frequency is 465 kilohertz. After calculating the capacitive reactance, the signal attenuation remains within an acceptable range. But if this were in the audio band, this value would block low frequencies. So it is only effective for the IF signal path.” He paused, then added, “If a 10-microfarad electrolytic capacitor were used instead, low-frequency response would improve, but the size and leakage current would both increase. In a portable device with limited space, 0.01 microfarads is a compromise between cost and performance. The schematic omits the bypass capacitor—possibly for simplification, or possibly to test whether one can judge the suppression of high-frequency self-oscillation.”

The specialist mentor on the right lifted his head and glanced at him. He neither nodded nor shook his head. He merely made a mark on the score sheet.

The next forty minutes were a barrage of questions. Stability of negative feedback in analog electronics. Timing logic in digital circuits. Then a Laplace transform derived on the spot. Lin Chen’s answers stayed within the same framework throughout: known conditions, derivation steps, conclusion. When he encountered a blind spot, he did not guess or force an invention. He simply said, “So far I’ve only been exposed to the basic concepts in this part. If necessary, I can set up the equations again from Kirchhoff’s laws.”

His voice was not loud, but every word landed on the beat. He discreetly wiped the sweat seeping from his palms against the seam of his trousers. The numbness in his left foot had begun to spread up into his calf. The seepage beneath the gauze had probably dried, crusted, or split open again. He refused to think about it. He counted pain as part of the loss budget, the way one calculates thermal loss in a circuit—leave a margin, keep running.

The chief examiner closed his folder. “That’s all. Go back and wait for notification.”

Lin Chen stood. The chair legs scraped faintly against the floor. He bowed and left the room. The sunlight in the corridor had already shifted to the edge of the window frame. He leaned against the wall and slowly let out a breath. Then he took out his ledger and crossed out “In progress” beside the entry for “Provincial Institute of Technology Interview.” He wrote: 09:55–10:40. Completed.

He needed to get back to the county town. Before two in the afternoon, he had to be back at school. He had missed the First Mock Exam, but he could not miss the test review and mistake log. That would be the basis of his revision for the next thirty days.

Bus station. Minibus. Bumpy ride.

He sat in the last row with Foundations of Electronic Information Experiments spread across his knees. The pages were open to the chapter on impedance matching. He took out his pencil and filled in the derivation process in the blank space. Outside the window, the scenery raced backward. Hills. Farmland. Scattered brick houses. His breathing adjusted itself to the rise and fall of the vehicle. Pain was an objectively existing parameter. He counted it into the loss budget, and then kept calculating.

1:40 in the afternoon. County No. 1 High School gate.

He swiped his card and entered. The white lines on the sports field had already been bleached pale by the sun. From inside the teaching building came the sound of papers being turned. He climbed to the third floor. The door to the homeroom teacher’s office stood open. Old Zhou was marking the math papers from the First Mock Exam. His red pen drew long crosses across the pages.

Lin Chen stopped at the doorway and knocked on the frame.

Old Zhou looked up. Behind his glasses, his gaze fell on Lin Chen’s dust-stained trouser leg and slightly pale lips. After several seconds of silence, he said, “You’re back.”

“Mm.” Lin Chen went in and placed the interview receipt from the Provincial Institute of Technology on the corner of the desk. “Materials submitted. Interview completed.”

Old Zhou picked up the receipt and glanced over the official seal and signature. “Independent admissions at the Provincial Institute of Technology. This year they’re only taking twelve students in the whole province.” He set the receipt down and pointed to a stack of papers beside him. “You were absent from the First Mock Exam, so it’s being treated as a zero. Your grade ranking has dropped past four hundred. If you’re still in this state for next week’s municipal unified exam, you won’t pass the preliminary review for recommended admission.”

Lin Chen nodded. “I know.”

“Good that you do.” Old Zhou pulled out a blank answer sheet and pushed it toward him. “Redo the final big problem from the math paper. Functions and derivatives. Forty-minute limit. Hand it in when you’re done.”

Lin Chen sat down and picked up his pen. The moment the tip touched the paper, his left hand pressed unconsciously against his right knee. His left foot gave off a faint heat inside his shoe. He adjusted his posture and shifted his center of gravity to the uninjured side of his left foot. He opened his scratch paper. On the first line he wrote: Solution.

Forty minutes.

He completed only one problem. The steps were complete, the logic airtight. In the final step he differentiated, substituted the extreme point, and got the correct answer. He handed the answer sheet to Old Zhou.

After reading it, Old Zhou said nothing. He opened a drawer and took out a bottle of iodine disinfectant and two rolls of fresh gauze. “Go to the washroom and deal with it. Don’t let it get infected.”

Lin Chen accepted them. Thanked him. Turned and left.

Cold water ran from the washroom tap. He rolled up his trouser leg. The gauze had already stuck to the wound. He soaked it slowly under the water and peeled it away bit by bit. The edge of the wound had gone pale; a small amount of tissue fluid seeped from the center. No pus. He dabbed on the iodine. The sting was sharp and brief. He wrapped it in fresh gauze and tied the knot. His movements were practiced. Like completing a piece of equipment calibration.

When he returned to the classroom, the evening self-study bell had already rung. His classmates all had their heads down over their work. In the air there was nothing but the sound of pen tips rubbing over paper and the occasional cough. Lin Chen sat in his seat and opened his mistake notebook. On the newest page he wrote:

“Absent from First Mock Exam. Zero points. 14 days until municipal unified exam. Provincial Institute of Technology result unknown. Current priorities: final big problems in municipal unified exam math/physics. Additional daily review load: 3 hours.”

He closed the notebook and took out Foundations of Electronic Information Experiments from his schoolbag. He turned to the last page and drew a set of axes in the blank space. Time on the horizontal axis. Progress on the vertical axis. He marked the first point. Then connected it into a line.

Nine at night. Evening self-study ended. One by one, the students left. Lin Chen packed his bag. Switched off the lights. Locked the door. The sound-activated corridor lamps lit up one by one with his footsteps, then went dark again one by one.

When he reached the school gate, old Chen the gatekeeper was reading the newspaper. Seeing him come out, he looked up and said, “The earliest bus to the provincial capital tomorrow is at six twenty. Don’t rush too hard.”

Lin Chen nodded and walked out through the gate. The night wind was cold. The streetlights on both sides of the road glowed dim yellow. He walked slowly. The pain in his left foot had already become a dull, heavy background hum. He no longer tried to fight it. He merely adjusted his stride so that each step bore weight evenly.

When he returned to the boiler room and pushed open the door, the smell of coal slag hit him in the face. He set down his bag, took off his shoe, and checked the gauze. Dry. Intact.

He sat on the edge of the bed and pulled the Nokia from his inner pocket. The screen lit up. No new messages. No missed calls.

He opened his ledger. Under “Transportation” he crossed out -3.5. Under “Medical” he wrote -1.0 (iodine/gauze). Under “Loan” he recorded: -2.0 (Old Zhou). Balance: -4.2.

The number was negative.

But the path was clear.

He lay down and closed his eyes. In the darkness there was only the sound of breathing and, far away, the occasional whistle of a train.

Tomorrow. Municipal unified exam review plan begins. Waiting period for the Provincial Institute of Technology starts. Foot injury must be kept from infection. Ledger must be filled back in.

He did not need a miracle.

He only needed scale marks.

At two in the morning, he woke up. Not because of pain. Because suddenly a solution to a problem flashed through his mind. He sat up, groped in the dark for his pencil and scratch paper, and quickly wrote out the derivation. Three lines. Five lines. Ten lines. The logic ran cleanly through. He stopped writing and tucked the sheet into his mistake notebook.

Then he lay back down.

This time, he slept deeply.

The next morning. Five-thirty.

He got up on time. Washed. Changed clothes. Checked his schoolbag. Ledger. Mistake notebook. Iodine.

He pushed open the door. The morning fog was thicker than yesterday. He stepped into it.

Then the phone in his pocket vibrated suddenly. Not a call. A text message.

Sender: Unknown number.

Message: “Student Lin Chen. Admissions Office, Provincial Institute of Technology. Your comprehensive interview evaluation has entered the review stage. Please mail the final draft of your personal statement and two recommendation letters (signed by high school teachers) to Room 301, Administrative Building, before 3:00 p.m. this Friday. Failure to do so by the deadline will be treated as voluntary withdrawal. Attached: recommendation letter template has been sent to the email address you provided.”

Lin Chen stopped walking. His thumb hovered above the screen.

Recommendation letters. Teacher signatures. Final draft of personal statement.

Time window: three days.

Distance: 120 kilometers.

He lowered his head and glanced at his left foot. The gauze lay flat. The pain was manageable.

He opened his ledger and wrote on a new page:

“05:32. New variables: recommendation letters and final statement draft. Deadline Friday 15:00. Need to coordinate teacher time. Need printing and mailing. Risk: medium-high.”

He closed the ledger and looked up ahead. The fog was beginning to break.

Next step: return to the classroom. Next step: find Old Zhou. Next step: cut these three days back down into executable increments of time.

He quickened his pace.

No longer hesitating.