This circuit for a frequency of 40 kHz was found in an old Electronic Design. There were no constructive data for the transformer used in the output.
This oscillator was found in a European circuit manual from the 1980s. The configuration can be...
The power supply shown has the circuit shown in the figure, and transformers of 5 + 5, 6 + 6, 7.5...
Found in Philips' 90s documentation, this small source can use modern transistors like the BD135...