This variable frequency (VFO) oscillator was found in a Japanese publication of 1962. Coil details (in Japanese, but can be deduced) are next to the diagram covering the 3.5 MHz band.
We found this circuit for vocal effects in the September 1990 issue of Radio Electronics magazine. The...
The original design of this circuit is from a 1978 publication. The circuit can be implemented with a...
We find this circuit in a 1980s documentation. The integrated circuit used is unusual today. The...