This programmable power supply allows you to control the output voltage using three digital TTL compatible inputs. The voltage can be set at three different levels, set by the user, and a combination of them.
This circuit can be useful for those applications where they are needed more voltage levels, as programmers, or simply to control the intensity of a lamp connected to the output. The voltage may be set between 1.2V-25V up to 1.5A with the limit of 20W that can be dissipated by the LM317 regulator.