This immobilizer circuit for vehicles was found in a 80’s Hands On Electronics. The circuit shortens the platinum to prevent its operation and thus the operation of the engine when started.
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....