Found in American documentation from the 90's, this circuit is very current and can be implemented with transistors of general use. Never use a power supply without a transformer.
This simple regenerative receiver for the medium wave range is from a 1956 Sylvania publication. Details...
This circuit for light data transmission (visible or IR) has a maximum speed of 1 Mbps and can be...
This circuit is from a 1967 publication. The Triac can be any of the TIC series. The series...