Found in old documentation, this oscillator operates with high voltage. The diode must be of the appropriate type with low current and an inverse voltage of at least 100 V.
The circuit shown is from an old European publication. In it we have the way to activate a relay...
We found this circuit in a European publication from the 1990s. Transistors are still common types...
This circuit was found in an American documentation and can be added to common amplifiers of any...