Safety warning: The HV section stores lethal charge even when unplugged. Always discharge through a 10MΩ resistor.
Warning: CRT circuits operate at voltages that can cause fatal electric shock or cardiac arrest. Do not build this unless you understand isolation transformers and discharge probes. Crt Clock Schematic
There are two primary approaches to building a CRT clock: Safety warning: The HV section stores lethal charge
Most reliable schematics use the following chain: Crt Clock Schematic