A features a specialized circuit designed to drive a cathode ray tube to display time, often by repurposing old oscilloscope tubes or small camera viewfinders . The core functional block of a standard CRT clock schematic includes a signal generator (typically a microcontroller like an ESP32 or PIC), a high-voltage power supply (reaching up to 2.2kV), and deflection amplifiers to control the electron beam's movement across the screen. Key Features of a CRT Clock Schematic