Firmware: Converts digit fonts into line segments (line() or Bresenham algorithm).
Many beginners try to run a CRT clock directly from Arduino PWM pins. It looks terrible. You need: Crt Clock Schematic
However, a CRT cannot display numbers natively. Therefore, the schematic includes a —historically a ROM chip like the 2513, but in modern designs, part of the microcontroller’s code. This logic translates the binary time data into vector or raster coordinates. For a vector CRT clock, the microcontroller outputs analog voltage levels (via digital-to-analog converters or resistor ladders) corresponding to the lines that form each digit. Firmware: Converts digit fonts into line segments (line()
The third dimension of the schematic is the (intensity). A potentiometer connected to the control grid adjusts the brightness. Meanwhile, another set of potentiometers governs geometry: horizontal and vertical position, size, and linearity. These adjustments are essential because electrostatic tubes are notoriously sensitive to drift; the clock you calibrate today might shift by tomorrow. The schematic reveals trim-pots (variable resistors) on the inputs of the deflection amplifiers, allowing the user to center the clock face. You need: However, a CRT cannot display numbers natively
On the schematic, you will find two identical ladders—R-2R resistor networks or dedicated DAC chips (like the classic DAC0808). One is for the X-axis (horizontal deflection), and one is for the Y-axis (vertical).