“Nice looking and simple to build Retro style Numitron tubes clock.
This time I will show you how to make a nice Retro style Numitron tubes clock. In addition to the correct time, the device briefly displays the Date, Year, and Current Temperature every 30 seconds.
For 74HC595 IC The total maximum current according to the datasheet is 70 milliamperes, which in this case is several times exceeded (about 160 milliamperes for digit 8), so that after a while the IC overheats and does not work properly. Another lack is that there are too many delays in the loop of code so the time is read only once in 60 seconds. In the picture you can see the finished clock made primarily according to the instructions on the page above. In the beginning, it works completely normally, but after a while, random segments are activated and IC-s, numitrons, or the microcontroller can burn very easily. In the first case, the problem was solved by using TPIC6C595 IC instead of 74HC595, which is provided for larger currents. Also should be taken care of that these two integrated circuits are not pin compatible.”