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.
This circuit was found in an old publicatio n from the year 1958. The circuit controls an external load by...
The focused circuit was found in the National Semiconductor's Linear Applications Handbook of...
If there is an indispensable household appliance in our kitchen these days it is the microwave...