Schematic Diagram

Variable DC Power Supply LM317 circuit and explanation

This DC power supply circuit is adjustable using IC Voltage RegulatorLM317. LM317 is a versatile and highly efficient 1.2-37V voltageregulator that can provide up to 1.5A of current with a large heat sink. Its 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. Its ok to use a trimpot if youre building a fixed-voltage supply.

Problems: Follow all the safety precautions when working with mains voltage. Insulate all connections on the transformer. Possible uses: Variable workbench power supply, fixed-voltage supply. Just about any possible application when no more than 1.5A is necessaryhis BlogThis!Share to TwitterShare to FacebookShare to Google Buz