Hello EE, I currently have a mini project that Studiot provided me with. Project is a kind of a multi-functional tester. But I want to add another feature to that tester. That tester has a 9V DC output, which gave me an idea. I always find myself searching for batteries and other power supplies. I have those DC adapters 24V 12V, but is there a way where I can build my own transformer, but with variable voltage outputs? Something like from 3 6 9 12 15 ... V(DC). Does anybody have schematics for this? What will I need to make this happen? I have some old DC adapters, old VCR , I even have old AC 220V to AC 24V... I will probably have to use a lot of Safety fuses and all.