We found this parallel regulator in a 1973 publication. Transistors admit equivalents and the output voltage can be modified by changing the zener.
The cut-off frequency of the filter shown in the figure can be adjusted to values between...
This circuit was found in a Popular Electronics from the 90s. The components used are all common...
This circuit uses a dual floodgate MOSFET not very easy to obtain today. Its handling is very...