This circuit was found in the magazine of radio amateurs 73 in a 90's edition. The components are current and the transistor is of general use.
Using SCRs, this circuit from a 1967 General Electric manual allows full wave load control with SCRs....
This interesting circuit from a publication from the 1970s, measures the intensity of the sound...
This simple NPN and PNP transistor tester configuration can use the low current range of a common...