Actually, this is ordinary regulated power supply, but the current expander using a transistor make this power supply become powerful.

Based on the datasheet, the stabilizer IC’s can deliver up to 1A output current. For example 78xx series regulators are available in different voltage ratings, but in any case the current should not exceed 1A.
The transistor [...]

This is the power supply circuit for general purpose usage.

The supply can be used for supply output voltages from 1 to 35V. The line transformer should be selected to give about 1.4 times the desired output voltage from the positif side of filted capacitor C1 to ground. Potensiometer R2 sets the output voltage to the [...]

Here is a Short-Circuit Protection circuit to derive the additional power supply from the main circuit. The main circuit is protected from any damage due to short-circuit in the additional power supply circuit by cutting off the derived supply voltage.
The derived supply voltage restores automatically when shorting is removed. An LED is used to indicate [...]