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 a 1999 publication. Its purpose is to flash two LEDs according to the...
This two-transistor emitter-coupled oscillator circuit with capacitive feedback was found in the...
This circuit is from an old operational amplifiers manual. However, the setting applies to modern...