A simple power supply circuit that can be used at laptops or other devices it's shown in this schematic .
This Laptop power supply schematic is based on a LM317 regulator an can be adapted to obtain the output voltage that we need.
If we want to modify the output voltage we must change the R4 resistor value ( the supply voltage must be at least 3.6 V above the expected output voltage).
The transistor Q1 it’s a MJ2955 or similar and should be heatsinked.
Diode D1, D2 and D5 are 1N5401 or similar type .
If you want to change the output voltage you need to change the value of R4 resistor like in this table :
|R4 value||Output voltage|