How I leared what a decoupling capacitor is for, the hard way

A decoupling capacitor’s failure isn’t theoretical—it’s smoke, glitches, and four hours of oscilloscope debugging, as one hardware engineer learned the hard way. The post details how omitting a 100nF capacitor near an IC’s power pin caused 200mV ripple that crashed a microcontroller every 37 seconds. It’s a vivid reminder that the cheapest part on a BOM can be the most critical.