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).
This amplifier with very high input impedance was suggested by Texas Instruments in a manual of...
Using only a ULN5804 integrated circuit, stepper motors up to 500 mA can be controlled from TTL...
Constant current sources are used in applications such as battery chargers, electrolytic tanks, etc....