This circuit was found in a Popular Electronics documentation from the 90s. It is possible to switch the frequency of an oscillator by voltage. The circuit can act as a shield.
This simple radio was found in a Popular Electronics from the 90s. L1 and L2 have 100 turns on a...
This circuit was found in Radio Electronics magazine from the 90's. The circuit is for small NiCad...
This automotive circuit was obtained from an 80's schematic from the integrated circuit factory...