Electrical Failures Caused by Voltage Fluctuation
Today I encountered a strange problem while using my computer and spent quite a long time troubleshooting before finally solving it.The IncidentAt home I plugged my electric scooter charger into the same power strip as my computer.After a while I left for something. When I came back and tried to use the computer:
[*]Mouse had no response
[*]Keyboard had no response
[*]The monitor showed extremely slight flickering (almost unnoticeable)
I began troubleshooting:
[*]Reseated and cleaned the RAM — no effect
[*]Updated drivers in Device Manager — no effect
[*]Added a ground wire to the computer — no effect
[*]Replaced monitor, keyboard, and mouse — no effect
[*]Replugged USB devices slowly — still no effect
After more than two hours with no solution, I suddenly suspected unstable voltage.
I changed the power strip — still no effect.Then I noticed the electric scooter was charging.The moment I unplugged the scooter charger, the computer instantly returned to normal.Root Cause AnalysisThis was a typical but not obvious electrical fault in daily life.1. Charger Creates Power Line DisturbanceDuring operation, the scooter charger produces high-frequency pulsed current, which pollutes the AC waveform and causes unstable voltage.2. Electromagnetic Interference (EMI)Low-quality chargers often have poor filtering, introducing strong high-frequency noise into the power line.3. Computers Are Sensitive to Voltage StabilityEven though a computer has a power supply circuit, unstable input voltage can cause:
[*]Monitor flickering (unstable GPU/backlight supply)
[*]Keyboard and mouse detection failure (USB voltage drop)
[*]System lag or reboot (motherboard and CPU power affected)
Why the Charger Produces PulsesCharging circuit working principle:PWM controller → Gate (G)
→ MOSFET switching channel
→ High-frequency switching current (chopping)
→ Battery chargingThe MOSFET repeatedly turns on and off at high frequency, producing pulsed current and electrical noise.MOSFET Structure
[*]Gate
[*]Drain
[*]Source
[*]Oxide insulation layer (semiconductor channel)
It is essentially a semiconductor switching device designed specifically for high-speed switching.ConclusionThis was not a computer hardware failure but a power quality problem caused by a switching charger sharing the same outlet.A key lesson:Some electrical faults are actually power interference problems, not equipment problems.Careful and systematic troubleshooting prevented secondary damage and helped accurately identify the real cause — voltage fluctuation and electromagnetic interference from the charger.
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