Clock hardware

The clock hardware is very simple. Let's go through the schematics quickly.


The PIC18 is the heart of the clock. Its internal oscillator runs at 8MHz, and the 4x PLL is configured, so we get 8MIPS.


The high-voltage is made of a FET driver (made from discrete and cheap components), a FET, self and capacitor.

Power outage detector

A simple transistor is enough to detect power outages. When VCC is present, the transistor conducts, and Plost is at logic-0 level. When VCC is absent, Plost is at logic-1.


The rest of the schematics is not worth to be discussed here, but the files can be downloaded in the download section. The clock is made of two small PCBs, sandwished on top of each other. The components of the tube PCB are soldered on the solder side, so that only the tubes are visible on the component side.