# Cell Phone Charger Power Supply For Your Projects

Have your batteries ever gone dead in the middle of an experiment? Isn't that disappointing? In this project we will convert an old cell phone charger into a power supply that you can connect to your electronic projects. Most cell phone chargers' output voltage is between 5 and 12 volts(perfect for electronic hobbyists). All you need to get started is an assortment of old cell phone chargers and a pair of wire strippers.
1.) First, pick up a charger and look for a small sticker on the adapter part of the charger (sometimes it is molded into the adapter instead). On the sticker look for the word "output". Look to the right of "output" and the charger should say something like 12VDC 500 mA. This charger is 12 volts DC or direct current. Keep looking through the cellphone chargers until you find the voltage you want.
2.) After you have selected the right charger for your experiment, cut off the end of the cord that plugs into the phone.
3.) Next, peel the cord apart and strip the ends of the two wires. For some cords there may be just one piece of cord that contains two wires inside. For this type of adapter, just strip the outer wire to expose the inner wires, and then strip the ends of the two wires inside.
Wasn't that easy? Now you can attach the two wire leads to your circuit and then plug the charger into the wall. Make sure that the two wires don't touch each other. The phone charger should put out around the same voltage it said it would next to "output." Now you won't have to stop experimenting just because your batteries go dead. These cell phone power supply's plug into the wall and supply voltage as long as you like.

Warning
Since cell phone chargers plug into the wall, they are dealing with high voltages and amperage's. Although the adapter converts the voltage and amperage to a much lower number, be extra careful at all times. Complete and experiment with this project at your own risk.

Phil B1 year ago
The phone chargers I have are not 12 volts, but 5 volts with an output of 1 amp. or less. They are not wire-wound transformers, but switch mode power supplies. Sometimes it would be handy to have an output of 3 volts or 4.5 volts.

I once tried using an LM317 variable voltage regulator on one of these switch mode power supplies, but either the regulator chip or the power supply shut down and there was no output. However, I recently tried something and it worked quite well. I inserted common diodes in series into the circuit to reduce the voltage. In practice, each diode dropped the voltage at the output about 0.3 volts per diode.

Some might suggest using resistors to drop the voltage, but they cannot easily handle the power (Wattage) that must be dissipated. By contrast, a diode can handle the 1 amp. that is fairly common to these circuits.

I did an Instructable on all of this, and you can view it here.
AptPupil2 years ago
Thanks, icecats, for the great idea. I have at least 10 of these in a box of "I better keep this just in case" stuff, just like many others, I'm sure. I have a few Arduino projects in mind that I want to make permanent that this will work great for. Much better than a battery supply.
Now, for my noob question. When the two wires are the same color, but one has some sort of print on the insulation, i.e., letters/numbers or just lines, which is positive? I would just get my multi-meter out but, it's not here. It seems to me that someone told me years ago that the one with print is generally ground. Can you confirm?

Thanks,
AptPupil
icecats (author)  AptPupil2 years ago
Usually the striped wire is positive and the negative is plain. However, if polarity is important in the projects you are doing I would really consider finding a multi-meter. Thanks for visiting this Instructable and good luck on your projects.
hobotraveler2 years ago
As I understand, and please correct ---- DC current will come out of the two wires?

Andy Lee Graham of Hobo Traveler
icecats (author)  hobotraveler2 years ago
If your adapter says Output: ?VDC, then yes DC current will come out of the wires.
tesla man2 years ago
You should include a warning in this instructable, because of the amperage. It only takes 30Ma to kill.