Here’s a LM338  power supply circuit with adjustable 3 terminal regulator to supply a current of up to 5A over a variable output voltage of 2V to 25V DC. This LM338 power supply will come in handy to power up many 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 components if 110V AC power supply input is required.

LM338 Power Supply Circuit Diagram

The mains input of the LM338 power supply is applied to the circuit through fuse F1. The fuse will blow if a current greater than 8A is applied to the system. Varistor V1 is used to clamp down any surge of voltage from the mains to protect the components from breakdown. Transformer T1 is used to step down the incoming voltage to 24V AC where it is rectified by the four diodes D1, D2, D3 and D4. Electrolytic capacitor E1 is used to smoothen the ripple of the rectified DC voltage.

LM338 Power Supply Schematic

Diodes D5 and D6 are used as a protection devices to prevent capacitors E2 and E3 from discharging through low current points into the regulator. Capacitor C1 is used to bypass high frequency component from the circuit. Ensure that a large heat sink is mounted to LM338 to transfer the heat generated to the atmosphere. For more info in LM338 Power Supply, visit 2-25V 5A LM338 Power Supply.

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