This project makes use of a LM338 adjustable three terminal regulator to supply a current of up to 5A over a variable output voltage of 2V to 25V DC. It will come in handy to power up lots of electronic circuits when you are assembling or building any electronic devices. The schematic and parts list are designed for a power supply input of 240VAC. Change the ratings of the parts if 110VAC power supply input is necessary.
As shown in the figure above, the mains input is applied to the circuit through fuse F1. The fuse will blow if a current greater than 8A is applied to the method. Varistor V1 is used to clamp down any surge of voltage from the mains to protect the parts from breakdown. Transformer T1 is used to step down the incoming voltage to 24V AC where it is rectified by the diodes D1, D2, D3 & D4. Electrolytic capacitor E1 is used to smoothen the ripple of the rectified DC voltage.
Diodes D5 & D6 are used as a protection devices to prevent capacitors E2 & E3 from discharging through low current points in to the regulator. Capacitor C1 is used to bypass high frequency part from the circuit. Make definite that a large heat sink is mounted to LM338 to transfer the heat generated to the atmosphere.
