Here is Ham radio power supply circuit using LM350T x4 in parallel for Amateur radio CB/RF/VHF. The output is 13.8V at 10A current. It is good circuit with PCB low noise RFI elimination.
If you want to a LM338 variable dc voltage power supply circuit during 1.2V to 30Vdc and can provide a current maximum to 5A.
This is simple variable power supply circuit 0-30V 2A using transistors basic circuits for beginner can builds easy with a few parts looks circuit 2 .....
When we build variable DC power supply,output 1A and adjust up to about 30V. Most use LM317, because high-efficiency, easy to apply and cheaper[...]
It is a modern circuit, Thus you can buy all components in the local store or buy KIT. And the important thing is the overcurrent protection.