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.
This vibrato circuit was found in Motorola's 1966 documentation. The circuit uses transistors of the...
The CMOS 4046 integrated circuit is not very common today, consisting of a very efficient PLL for...
We found this circuit in an old publication. The transformer has a 9 or 12 V secondary, and the...