Nixie Clock #3

The 3rd nixie clock I built, in 2004. It was a birthday present for one of my brothers. It was my 1st transition to AVR (mega8). I had previously used 8051 variants. The nixie tubes are Russian IN-14s, and the dekatron is a Sylvania 6802. The HV switcher is based on the old 555 timer chip, and produces both +200V, for the nixies, and +500V for the dekatron. It also uses a DS1307 RTC and has an hourly chime. It "auto detects" line frequency for either 50 or 60Hz. If no AC is seen, it uses the 32KHz xtal of the RTC.