This circuit of the 70's uses transistors of the time. The circuit can amplify signals from 10 Hz to 100 kHz and modern equivalent components can be used. The circuit is from Ferranti.
This conventional power supply circuit with the LM317 was found in a 1987 publication and its...
This circuit was found in an 80's EDN. The circuit uses a current common CMOS, the 4093 powering...
This detector is from the 1990 Motorola Dataar Databook, but can be adapted to work with more...