This configuration can be found in several articles on this site. The one shown in the diagram is from the datasheet of the LM101 series amplifiers, but it can be implemented with other types.
This circuit was found in the September 1976 issue of Radio Electronics magazine. The circuit is...
We found this circuit in a 1995 documentation. It operates in the 3.5 MHz band that corresponds to the 80...
This 3-decade operating range VCO was found in a 90s Popular Electronics. The circuit uses...