We found in this American documentation this circuit for activating common cathode displays. In it we have the way to cascade the 4033 to drive two displays (dozens and units).
Indicated for applications with a PC, this circuit was found in an English documentation from...
The figure shows an excellent benchtop isolation transformer system. This circuit was suggested by...
This circuit of a 1964 Electronic Design uses a photodiode from the time. Modern equivalent can be used....