Simple plug-and-play breadboard power supply with current monitoring output, LED indicators, switches for both rails, and decoupling capacitors.

Power-section schematic for a 12V DC input generating +4V for a 4G module, +5V, and +3V3 rails with input TVS protection and regulator thermal notes.

Battery-powered nRF52840 wearable power-tree schematic with USB-C charging, nPM1100 PMIC, 3V0, 1V8_SGP41, and 5V_SPS30 rails.