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.
Casing:
I have decided to make a rack mount enclosure from scratch. Project wouldn't be really “hard core” homebrew without one.
This front panel is epic! It could pass for an original HP instrument from the 1950s. Designed and fabricated to perfection.