This symmetric 30 mA x 15 V power supply was found in the Ferranti transistor manual from 1974. Transistors are common types at the time.
SST LLE Series Liquid Level Sensor Switches Available through Mouser Electronics, these solid...
The first circuit is shown in figure 3 and uses a 2N2222 transistor or equivalent. This circuit can...
This circuit shows how an inductive capacitance can be used to reduce the voltage of Power supply...