Functions of the clock:
- You can course or fine adjust time with 4Hz pulse
- Master reset time all nixies or seconds only.
- Change brightness of Nixie Tubes.
- Temporary switch them on for 20s.
- Alarm can be set for exact time with silent or loud function.
- 1pps output / input of square TTL, CMOS level or sine wave .
- 12VDC output for OCXO (not constructed yet)
Block diagram (kind of):
4.194304 MHz XO -> CD4521 frequency divider provide (in)accurate 1 Hz pulse :)
Pulses are counted by CD4017 decade logic and 24 hour reset is provided by two 2N222A NPN transistors.
I have used relays between CMOS chips and IN-1 Soviet Nixies to achieve this soothing sound of clicking relays.
I have decided to make a rack mount enclosure from scratch. Project wouldn't be really “hard core” homebrew without one.