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.
Transistor Variable power supply 1A, 0-30V project with PCB. Using transistor boost current to 1A. No IC. No Zener diode. But steady voltage.
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 .....
This is AC variable power supply circuit that apply output of 0-30V at 3A by use electronic components, bridge diode,and more, to control voltage[...]