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Numitron IV-9 clock with RTC 3231

When I was looking on the internet on a website, I saw this nice little display

The numitron:

I decided to make a clock with the numitrons and I bought six of them.

The datasheet says that the current may be between 17 and 22 mA, and the voltage between 2.8 and 4.5 VDC. I am using the shiftregister TLC5916.

With only one resistor you can control the output current of all the 8 channels.

With a resistor of 1000 Ohm, the constant current is 18.75 mA.

In fact the segments of the display are incandescent filaments. To protect the segments I put a diode (1N4007) in series with input 1 of the display, so the 5VDC is now 4.3 VDC per segment.”

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