Hi I need a power supply for my project. I intend to take the plug off the the phone charger but I have no multimeter to know which line is positive. One of the two wires have a white stripe running on top of it. Would that be the positive?

 

Hi I need a power supply for my project. I intend to take the plug off the the phone charger but I have no multimeter to know which line is positive. One of the two wires have a white stripe running on top of it. Would that be the positive?

I have experienced both cases where the white strip indicates the positive and cases where the strip is on the negative.... the only way to be sure is to use a multimeter and check.

 

Here is a simple and cheap low voltage polarity checker you can build:

The probes can be just plain wire.

Both LEDs need to be in the circuit, as they protect each other from excessive reverse voltage.