This circuit triggers in 100 microseconds in case of excess voltage. The adjustment is made in the pot. The circuit was found in 1969 documentation.
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....