This current boosting circuit uses an op-amp and 3 transistors. The current depends on Q1. The circuit is from the 1995 Encyclopedia of Electronic Circuits Volume 5.
This circuit was found in a General Electric documentation from 1966. It uses discrete components...
One of the problems with common 3-terminal regulators is that the internal reference, normally 1.25 V,...
Found in a 1970 documentation, this SCR bistable can be implemented with modern equivalent SCRs. Observe...