This 5 V power supply for TTL, Shields and microcontrollers is old, and the components can be replaced by modern equivalents. Transistor Q1 can be a TIP31 and Q2 can be a BD135.
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...