Suggested by Texas Instruments in 1980s documentation, this circuit uses a component of the era. The operating characteristics are given next to the diagram.
This circuit was obtained in a 1991 Electronics Handbook. The publication no longer exists, but...
This is another possible version of a negative voltage generator using a 555 integrated circuit. The...
This circuit is from a 1965 Electronic Design. The transistors may be general purpose and the...