Found in a 1969’s EDN, this circuit provides 4.5 V with a 100mA current for digital logic. The circuit uses transistors from the era.
In the figure we have the way to implement a 5 to 45 V zener diode with 50 mA of maximum current...
We found this circuit in a Radio Shack documentation from 1977. The circuit serves for a link of...
This circuit was found in the 1977 National Semiconductor FET Databook. The FET can be the BF245...