The source shown in the figure provides output voltages in the range of 1.2 to 25 V with currents up to 3 amps. The voltage regulator integrated circuit can be presented in TO-3 metal enclosure or TO-220 plastic, but in both cases it must be fitted with a good heat radiator. The capacitor of 100 nF as well as that of 1 ?F should be mounted as close as possible to the integrated circuit. The transformer has primary winding according to the power grid and the diodes can have currents larger than specified. This circuit is suggested by National Semiconductor.
