How to Build a Bench-Top Power Supply

Step 9 Possible Improvements and Modifications

This circuit is highly adaptable. You can adjust the values of R1 and R2 to suit whatever components you have on hand. I actually designed my personal circuit to use a 0 - 4K pot that I had on hand. If you want to change the resistors, use the following formula:

VOUT = 1.25 * ( 1 + ( R2/R1 ) )

The value of R1 should be between 10 ohms and 1000 ohms. Anything higher and the voltage regulator won't behave. If you decide to make any changes to the circuit, you should refer to the datasheet for the finer details. This site is another good reference for using the LM317T.

Ideas from the comments
-You could enclose the entire circuit in a plastic project box. That would prevent the back side of the board from shorting out if it came in contact with a metal tool.
-You could buy a multimeter that is to be used only for tuning the output. Cut off the probes and solder the wires directly to the outputs for a permanent solution. If the multimeter had interchangeable probes, you could buy an extra set for use with other projects.

Comments

[electronicdude]

I looked on the web and you could add that anolog to digital converter chip with some led displays. Then you could see what voltage it was on. I have only seen one person on her with a similiar idea, but he just added a multimeter to it,