This circuit was obtained in a 80s RCA documentation. The circuit uses components from that time. These components can be replaced by modern equivalents.
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....