Relay HAT Schematic – Post‑Validation Fix Plan (ULN2803A, Buck → Pico, LEDs, Optos, Testpoints)

Project featuring stopwatch based on Arduino nano and DYI 7 segment clock with max7219 and ULN2803A transistor array. For comunication project uses nRF24L01. #Arduino #Nano #Shield #project #nRF24 #max7219 #ULN2803A #Stopwatch #Firefighting_sport