Measure multiple voltages and display to LCD?

Hi all.

I'm building a benchtop power supply for electronics/computer work from a computer power supply. I plan to have a 12v line, 5v line and a 3.3v line. What I want to do is measure the voltage on each line and output the readings to an LCD display (16x2 character display most likely). It only needs to update once a second or so. If possible I'd like it to display the voltages of all 3 lines on the LCD at the same time.

Is this possible? If so how would I go about setting it up? Thanks in advance!

Thanks for the info and the links. I'm trying to do this a low-cost as possible, seeing how I've got a spare computer PSU laying around that I'm going to use for this. The PSU puts out 12v on the yellow line, 5v on the red and 3.3v on the orange. So the 5v and 3.3v I could monitor directly, how would I go about splitting the 12v with a voltage divider and modifying the code so it still displays the 12v output?

how would I go about splitting the 12v with a voltage divider and modifying the code so it still displays the 12v output?

How about using a voltage divider consisting of 3R and R (12K and 3.9K would be close) to give you an input to the Arduino that is 1/4 of the original 12v? You could then easily multiply that reading by 4 (shift the result two places) for the display.

Don

Keep in mind many switching power supplies, like those used in PCs, have a minimum load spec. Voltages will not be stable unless this is met. A simple way to meet this spec is to attach two hard drives to the supply to act as a dummy load.

For example, I have a supply that requires almost 20watts of load, spread across the various voltage outputs, to be stable.

Well I'm planning on it running a few fans and some lighting, so the load should be covered. I'ms till working on the details though. Thanks so far for the help!