This circuit was found in a 1970 American publication. The FETs are power types according to the desired output current. The operational can be replaced for modern equivalents.
The sensor for this Intersil circuit (1983 databook) is a common silicon transistor. The trimpot...
This circuit is from a 1972 Motorola publication. The used transistor can still be found, but it...
This is the simplest setting for lighting an LED. The circuit is from old English documentation that got...