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.
The 50 kHz signal generated by this circuit is applied to a low impedance inductive transducer. A...
This different audio amplifier was found in a 90's Electronic Design. The circuit uses components...
This circuit converts a resistance in the range between 1 k ohm and 1 MΩ to a signal in a...