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 was obtained from an English magazine from 1985. The N414 is a complete, not easy to...
Found on Popular Electronics from 1969, this circuit can be implemented with components that are...
This circuit is from a book of transistors from 1954. The transistors are from the time and the...