This circuit is from the 80's documentation. The integrated circuit is from the time but can be implemented with modern equivalents. The power supply must be symmetrical.
This blocking oscillator configuration was found in a 1964 American book. The circuit can be...
This low power circuit for the FM band was found in a spy book from the 90s. The tunnel diode is...
This transmitter, indicated for espionage applications, is permanently powered by the power grid....