We found this circuit in a Texas Instruments documentation from the 80s. The circuit uses simple power source and the frequency depends on C1 and R1 basically.
We found this circuit in an old American documentation. SCRs can be modern equivalent types. The...
When the voltage exceeds the value given by the zener, this circuit from a 1990 documentation...
This circuit was found in a 1970s documentation. The components are from that time, and...