This charger for automotive use provides a 0.42 A output current. We find it in an American documentation from the 90's. The transistor must have a heat sink.
This circuit, suggested by Siemens, allows the activation of 24 V solenoids from TTL LSL signals,...
In the figure we have the way to linearize the response of a TTL port with the use of a feedback...
In the figure we have the original version of an amplifier with high input impedance, 1.2 M ohms....