Controlling 4 Russian IV-3 VFD tubes with an Arduino Uno. Each tube counts from 0 to 9 and the decimal separator dots form a binary counter. Every few seconds, the blue tube backlighting LEDs are faded.
As a challenge, this circuit was designed only around a 555, standard NPN and PNP transistors and of course some resistors and capacitors. No (mos)fets, coils, special IC's, SMT parts, ... were used.