Friday, December 31, 2010

Variable DC Power Supply With LM317

This DC power supply circuit is adjustable using IC Voltage Regulator LM317. LM317 is a versatile and highly efficient 1.2-37V voltage regulator that can provide up to 1.5A of current with a large heat sink. It's ideal for just about any application. This was my first workbench power supply and I still use it.

Since LM317 is protected against short-circuit, no fuse is necessary. Thanks to automatic thermal shutdown, it will turn off if heating excessively. All in all, a very powerful (and affordable!) package, indeed.

Although voltage regulator LM317 is capable of delivering up to 37V, the DC power supply output circuit here is limited to 25V for the sake of safety and simplicity. Any higher output voltage would require additional components and a larger heat sink.

Make sure that the input voltage is at least a couple of Volts higher than the desired output. It's OK to use a trim-pot if you're building a fixed-voltage supply.

Follow all the safety precautions when working with mains voltage. Insulate all connections on the transformer.


  1. Salam kenal, kunjungan pertama nih. NIce blog! Ditunggu kunjungan baliknya ya

  2. Hi friend,

    Variable dc power supply using LM317 regulator project provides the schematic, and the parts list needed to construct a simple dc power supply from an input power. Thank you...

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