Found in a 90s EDN, this circuit is indicated for power control through a 4-20 mA line. The circuit makes use of optical couplers of the time.
This simple alarm circuit was found in a 1998 documentation. When the sensors are activated, the...
This circuit was found in an old American documentation. The integrated circuit used is uncommon...
Found in a 90s Electronic Design, this suggestion to have a higher voltage in a fixed regulator...