It is VFD display, standard 4x7 segments and colon from Futaba.

The clock is based on circuit MM5387AA/N – it is a clock synchronized to the network 50/60Hz to four 7-segments displays of 24/12 hour format (on this board it is only 24). It also has an alarm. Only pins for fast and slow time setting, time and lasting of alarm and nap were used. Turning off the alarm was not provided. 12V beeper is the indicator.

Power supply:
It is a transformer from an old power supply with 3 and 12V windings, both AC, because lamp glows properly only when AC powered.

Housing was made of a wooden box. All the buttons and potentiometer for the display brightness regulation are placed at the back. Buttons were made of old transistors in metal housings, the biggest one turns on the nap.


And the video:


Link to original thread (useful attachment) – Zegar VFD w drewnianej obudowie.