ATX monitor is a cheap way to build a work bench power supply from an old ATX block. It uses an arduino and a LCD display to monitor and display output values (both voltage and current) from 3.3V, 5V and 12V rails.

• 1 x ATX power supply
• 1 x Arduino (pro mini)
• 1 x An LCD display compatible with LiquidCrystal (YB2004A 20x4 lines)
• 6 x Some resistor to build voltage divider, value is not important as you avoid more that 5V output
• 3 x ACS 712 current sensor modules (you can also build yourself with a raw ACS712 and a couple of resistor and capacitor)

I used an Arduino pro mini.

• LCDRs -> Arduino pin 4
• LCDEn -> Arduino pin 5
• LCDDb4 -> Arduino pin6
• LCDDb5 -> Arduino pin7
• LCDDb6 -> Arduino pin8
• LCDDb7 -> Arduino pin9

• 12V ATX output -> voltage divider -> Arduino pin A5
• 5V ATX output -> voltage divider -> Arduino pin A4
• 3.3V ATX output -> Arduino pin A3

• 12V rail ACS712 -> Arduino pin A0
• 5V rail ACS712 -> Arduino pin A1
• 3.3V rail ACS712 -> Arduino pin A2

Adjust values from DEFINE section to match your hardware.