Negative voltage generator.
I originally designed this circuit in order to repair an Icom 701. It is a fairly standard application of the ubiquitous 555 chip. The output is dependant on the supply voltage and the load, you will not get -9v out with 10v in for example. There is no such thing as a free lunch, and the diodes drop some volts. Replacing silicon diodes with Schottky types will improve things a little. With a bit of imagination it can be constructed in a very small volume.
The available current is quite small, about 20mA maximum into a 500R load. Efficiency around 30%. If I recall correctly, the 701 needed just a few uA, so well within the capability of this circuit.
Having recently purchased an SSB i/f PCB that needs -ve volts on the mixers and op-amps, I searched my notebook for
the schematic and made an electronic copy on my Samsung tablet, using the amazing app, SCHEMATIC.