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.
When the temperature rises above the value adjusted by P1 the relay triggers on. The rated voltage for the...
This oscillator for frequencies up to a few tens of kilohertz was found in a 1970s documentation. The...
This small transmitter, found in a 1982 publication, sends its signals to an FM receiver placed...