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.
This is First Variable DC Power Supply 1.2V to 30V 1A using LM317. using a few parts and build easy with PCB layout and can fine adjust voltage output.
Not suitable for beginners!
This is a 3A adjustable regulators using IC-LM350 that looks like LM317 Variable DC Power Supply, but high current higher 3A, adjust voltage 1.2V to 30V
Do Not Make This circuit If You are not brave enough.