This circuit, very critical due to the frequency at which it operates, was found in an American documentation that uses a resonant cavity in a beer can. The transistor can be of any type for RF.
This circuit was found in an Electronic Design from 1967. The circuit uses two triacs being T2...
Found in old American documentation, this circuit can use crystals between 27.5 and 33 MHz...
This shield from the 60's uses a germanium transistor of the time and a common type of relay of...