As you know, VFD is a kind of vacuum tube, not for amplification but "only for display". Similar vacuum tube can be found, for example "Magic Eye 6E5" or famous Nixie tube. These tubes are more likely original vacuum tube and requires, generally, more than 100 V plate voltage. But in the case of VFD, it will work much less voltage (still high, though) around 20V or so. This time I made simple VFD clock consisting of

(1) MCU: ATMega328P


(3) Voltage converter (5 V to 20 V) by TI LMR62421

(4) Transistor array TF62004

(5) Shift register 74HC164, and

(6) VFD Russia IV-3A

The pinout of IV-3A VFD is compatible with IV-6 Nixie (not voltage but just pin-compatible) and also LMR62421 is with TPS61040. With shift register and transistor array, high voltage (20 V) is switched by serial data from ATMega328. Four NPN transistors (2SC1815) are 4-column switching enables dynamic driving.

I can see the time but is not so clear digit display through camera due to dynamic driving.

Just around 4 to 5 V is enough to drive it. Actual operation is shown in the following movie.. just for fun!