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.
This basic configuration can be found in a lot of articles on this site. In this case, the relay...
This circuit is from American documentation from the 1980s. The transistors are general purpose...
The circuit is simple, as it uses only one transistor and a relay that can be MC2RC1 or MC2RC2,...