We found this parallel regulator in a 1973 publication. Transistors admit equivalents and the output voltage can be modified by changing the zener.
Found in a 1960 Sylvania manual, this circuit can be implemented with a modern equivalent...
This configuration, already presented in other points of this section and website, is of a...
We found this precise crystal oscillator for the 144 MHz band, depending on the crystal used. The...