This low power circuit for the FM band was found in a spy book from the 90s. The tunnel diode is not an easy component to obtain and the power can be supplied with a single button cell.
With this circuit it is possible to use a common hair dryer as a hand dryer. The circuit is timed...
This circuit was obtained from an English magazine from 1979, but can be easily assembled today...
This circuit was obtained in a 1975 magazine, but it can be easily assembled using BC548...