Using a varactor or varicap, this 1969 Electronics World circuit has a modulation range from 75 kHz to 52 MHz. Modern equivalent components can be used.
This configuration was obtained in the SGS manual of linear integrated circuits of 1982. The...
This circuit works with only 1.5 V and can be powered by a solar panel. The circuit is from 1991....
This circuit was obtained in a 90s Popular Electronics. It is used for tuning on AM radios. The...