How to find polarity of a power supply that's lacking the customary markings
- by Nosredna
If I have a power supply (not a computer power supply, just a battery-replacing wall wart) and it doesn't have the usual polarity marking, how to I know if the tip is positive or negative?
Update: I couldn't find my multimeter. I did find a model number on the power supply and typed it into Google. Some guy selling a bunch of power supplies on eBay had checked it and found that it was tip positive, which is what I needed!