This shield circuit is from an American documentation from 1969. The components can be modified according to the relay and power, and the coupler can be of a modern type.
This circuit produces a IR beam with a frequency adjusted by the 100k pot. The circuit can be used in...
This voice scrambler and descrambler circuit was found in a Radio Electronics from July 1963....
This transistor source was found in a 1990 documentation. 2N3055 transistors must be equipped with...