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.
Instead of high voltage, these tubes require high current driven through external copper coils (yoke). The schematic here utilizes heavy-duty audio power amplifier ICs (like the LM386 for tiny tubes or TDA-series chips for larger ones) configured as constant-current drivers. Section C: High-Voltage Power Supply (HVPS) Crt Clock Schematic
The raw output from a DAC is usually 0V to 5V. To bend an electron beam across the face of a CRT, you need significantly higher voltage swings. The schematic for this section depends entirely on whether you are using an electrostatic or electromagnetic CRT. However, a CRT cannot display numbers natively