This static switch circuit or solid-state contactor was found in a Motorola documentation from 1968. The circuit can control a 5 A load with the indicated transistor.
We have dozens of similar projects in articles and circuits on this site. This is from Radio...
This circuit with an unusual configuration was found in the January 1974 issue of Radio...
This interesting circuit from 1967 documentation uses three series lamps to regulate the voltage...