How to check the polarity?

Question

The wire ofmy Mobile Charger has cit off & I myself soldered it. Now I like to how to check the polarity of the pin before connectin with the Mobile.

Answer 1

You will either need a multimeter, and check the voltage with respect to 0V or failing that, you could use a LED if you have one, or could get hold of one:

An LED is a diode, so will only light if the polarity is correct. if you touch the two terminals of the LED to the two contacts of the charger's connector and it lights you know the charger's +ve connection is the one touched by the longer leg (assuming uncut) of the LED, and the -ve connection is that touched by the leg entering the LED's body near the flat spot. If the LED doesn't light, connect it the other way.

The chances are the charger's output is around 5V which is more than the max operating voltage of most LED's, but it won't burn the LED out immediately, you'll get at least 10 seconds or so before it goes (it'll get hot tho!)

Answer 2

you need to use a multimeter . this is the most useful and reliable method to do it

Answer 3

The best way is to use a multimeter. A multimeter is a meter that measures multiple readings hence the word multimeter. They usually measure DC volts, AC volts, Ohms. Some more expensive models measure continuity and have diode check and frequency measurement too.

To test your charger polarity simply place the two test leads on the output pin of the charger. You may need to probe inside the tube of the pin to get a reading. Assuming you are using a newer digital display meter the voltage will read on the meter for example 4.95V. If this is the case then you need to note which test lead is probing the inner core of the pin. If its the red lead then you have connected "centre positive" and if its the black lead you have connected "centre negative".If you are measuring the voltage polarity reversed then the display will give a minus sign before the voltage like this -4.95V. It is still the correct voltage but simply means you are measuring it with the leads the wrong way round, or reverse polarity. On the older analogue meters the pointer needle used to shoot the wrong way to the left if you measured wrong polarity. Assuming you know the polarity of the phone socket connection you should now be able to determine if your repair is compatible. Some chargers have the polarity marked on them. A small symbol denotes centre positive or negative. It looks like this go to;

www.accesscomms.com.au

I hope this has been of some help.