In fact, it is a night light system that automatically turns on the outside lights when it gets dark and turns them off at dawn. The circuit only applies to incandescent lamps.
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....