This Single output 12 V / 5A power supply provides power for equipment that requires a large energy (Audio amplifier for car radio, CB, etc.). It is built around a voltage regulator like the LM338 and capable of providing voltages between 12V and 15 V (13.8 V for example). This circuit can provide a maximum current of 5 A.
The diagram above shows all complete circuit of power supply, and is based on the use of common components, except perhaps for the voltage regulator was chosen here, an LM338, which is rarely used instead of the LM317. The use of integrated controller LM350 (3 A) to replace the LM338 (5 A) can be done if the needs of output current does not exceed 3A. Note that the LM338 and LM350 are nearly the same price, would be better if you order a LM338.