A very basic power supply that can be adjusted over a range of about 1.5 to 35 volts DC. If you add a heat sink (included) you can run it as hot as 2 amps output otherwise about 60mA (at)12 volts. This is a text book circuit using an LM317 which is a 3 terminal regulator in a TO220 package. Input can be either AC or DC DC input must be at least 2.5V above the required voltage output. You could use a surplus transformer from 12 volts up for input