This regulator can be controlled by a logic signal. The circuit is from an Electronics Now from the 90s. Note that the switching transistor is before the integrated circuit.
This circuit was found in a telecommunications publication of 1978. Its purpose is to obtain...
This setting appears with variations at various points on this site. This is from a Motorola...
This circuit is from a 1967 documentation. The circuit uses germanium transistors and has an...