Indicated for the protection of three-phase systems, this circuit was found in an American documentation of the 70's. The circuit can be implemented with modern components.
This circuit was found in Mullard's 1960s transistor manual. The circuit uses germanium...
This circuit was found in a 1980s documentation for amateur radio. The circuit is for 9 MHz...
This small transmitter of just 15 mW for the 3.5 MHz (80 meter) band was found in a 1986 Sylvania...