This circuit transforms 0 and 6 V signals into -4 to 10 V signals and can be used in a shield. The circuit uses transistors that are still common today.
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...