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.
The project is from a 1992 publication, but totally current by the components it uses. The LEDs...
Other CMOS gates can be used in this sensor, which we found in the July 1995 Electronic Now...
In this circuit we show how to modulate the pulses produced by a 555 in frequency. The circuit can be...