This circuit was found in a 1970s American documentation. It can be applied to almost any regulator. The transistor used admits equivalent, depending on the circuit current.
This amplifier was found in a Japanese publication in 1972. Transistors are uncommon today, and...
The current of this source is 200 mA at the most, and the output depends on the zener that may...
Found in Mallory documentation from 1968 this circuit uses an integrated circuit from that time. The...