This circuit was found in an American documentation two years 80. The MOSFET is of double port, difficult to obtain now and the circuit has a tuning frequency determined by RC.
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...