The scenario
An Arduino detects an external event and drives a 5V pulse through a current-limiting resistor into an optocoupler, which isolates and momentarily connects the laptop power button contacts to start the laptop.
What is in this drawing
Read the decisions behind it.
01
Use an optocoupler for galvanic isolation between Arduino and laptop button signal
02
Add a 220Ω series resistor to safely limit optocoupler LED current
03
Include a decoupling capacitor and a pull-up test button for stable and testable operation
Reuse when an embedded controller must automatically power on a laptop with a momentary power button, such as scheduled boot, remote wake, or test automation.
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