A flex thin 5 layer board with lots of caps and wire-bonding pads: LHCb UT’s front end PCB prototype.
There are lots of MCUs with many GPIOs, but apparently, they’re never enough. Wanna 40 more?
NE555 and Digital potentiometer based pulse delay generator: trigger it and get a pulse back after some delay!
Triac control circuit with built-in zero crossing detection and open collector output
AC-DC SMPS converter with <0.3W standby consumption and 4200 Vrms Pri-Sec. isolation in a 42 x 42 x 22 mm package!