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.