This power source takes advantage of an old valve transformer that is no longer used and can supply high voltages in AT1 and AT2 to supply valve projects and low voltages in B1 and B2. B1 is not stabilized and B1 is regulated and variable; Transistor Q1 can be a TIP31 that must be mounted on a heat radiator. P1 must be made of wire. The circuit is from the book Science Fair Projects by Newton C. Braga.
