Easy DIY Wall Charger for Cell Phone or Portable Gaming System!


If you don’t care about why I did this or do not want to learn about voltage, you can skip straight to the “How To” section.

Also, none of us at Geek Sweat are responsible for anything that happens from you doing anything that involves electricity!

The Story

I recently lost all 3 of my wall chargers for my cell phone and was left with only USB plug-in chargers to keep my phone alive. This little irritation quickly turned into a big problem, constantly leaving me with a dead phone battery or scrambling to find a computer to plug into. To make things worse, my bank account had spent the last 2 months telling me, “do not to eat food, let alone, spend $20 on a phone charger… You are broke!” I was hungry and powerless and my phone became nothing more than a paper weight in my pocket.

And then a solution hit me like a line drive to the face!

I had been hooking up 6 120mm computer fans in a series, giving my computer unbridled air cooling during heavy game play. Being the broke-ass, creative engineer that I am (well broke and cost-free solution-oriented) I was using an old 12 volt wall plug that was once used to connect an ancient linksys router to power my 6 awesomely amazing MasterCooler 120mm fans that just so happen to run on 12 volts. (I hope you read this MasterCooler, your products are great and inexpensive and you should send me free samples!) Why couldn’t I do the same with an old 5 volt power adapter and my USB chargers?

The logic crosses over. I grabbed a 5 volt wall adapter and cut it up, cut up my USB connector, and viola, made my own phone charger! The beauty of the solution lies with in its simplicity. You can do this with just about anything that runs off of batteries or a controlled voltage power supplys.


This section gives you some brief knowledge before you start. Skip if you don’t care, but be warned, electricity is dangerous business!

Your home is powered by AC electricity connections. The outlet you plug into has 120 ~ 240 volts running through it, which is why you usually die when you stick a paper clip in the socket using your tongue to push the paper clip in. AC means alternating current. The current goes up and down or to a positive peak and then past zero to a negative peak, making a sine wave shape. It does this every 17 miliseconds or every almost 6 times a second. This means, when you touch a live wire, 120~240 volts strikes you 6 times every second, causing your muscle to clench and skin to fry and insides to boil 6 times a second. It is like hitting a light switch off and on.

DC is called direct current. Electronic equipment or anything with circuits built in cannot take that type of electrical torture. That big black box on the wall plug contains a transformer, a bridge rectifier, and a capacitor amongst other things. The transformer converts AC into smooth DC, the bridge rectifier regulates the voltage to a more suitable level and the capacitor smooths the smooth DC into steady DC. Smooth DC still has some wobbles, making it problematic for intricate circuitry but basic circuits can take smooth DC.

Building a DC power supply is very possibly and cheap (and easy) but it is also extremely dangerous due to the fact that you can BURN YOUR FUCKING HOUSE DOWN! So…. DO NOT BUILD A DC POWER SUPPLY! YOU WILL DIE! Cool Beans!

mA, mAH, Amps: mA is milliamperes, mAH is milliamperes per hour, and Amps are all the same. Amps are the amount of electrons that pass through one point. Then voltage is the amount of power each amp has. And amps * volts gives you wattage. A milliampere or mA is .001 amps. 1000 mA’s = 1 amp. So, if your device requires a 9volt power source and the battery says 1500 mAH that means that it requires every every coulomb (which is 6.241 × 1018 electrons clustered together) to carry 9 volts of power per second to the battery pack. And vice versa, the battery drains 9volts a second at 1.5 amps per hour. The battery runs at 1.5 amps per hour (1500 milliamps per hour) and every electron coulomb holds 9volts of power, then we bring in wattage and seconds and more stuff and it gets a little confusing but essentially, mAH means that the battery drains that many milliamperes per hour. The voltage decides how many hours that battery will last. A phone can drain more battery under certain loads while a gameboy will stay steady at 1.5 amps per hour with a 3volt battery source. This is because of science and dark voodoo magic!

The ”How To”


  • Wire Cutter/Stripper (not the stripper at the Cheetahs with that gross scar)
  • Electrical Tape or Heat Shrinks
  • USB Charging Cable
  • Correct Voltage DC power supply (mine is 5 volts because a USB cable draws 5 volts of power from your computer or car charger etc..)
  • Soldering Iron (Only if you want to! You don’t need to solder any of this)

Step 1

Find a DC power supply that has 5 volts and has around a 500 mA output.

  • You can use PS’s with any mA, it just means that 500 mA will be transfered to my battery pack which is rated at 1150 mAH. This means that a 500 mA charger will charge my phone in 2.3 hours. 500 milli-amps will be transfered to the battery pack every hour and if my battery pack holds 1150 millamps that means that 1150 divided by 500 = 2.3, the total number of hours my battery will charge at.

Step 2

Cut the cable on the power supply and cut the USB cell phone connection (see images)

The USB cable will have a red, white, green, and black wire. You need the red and black wire. Red is positive, Black is Negative, connect the red USB and red Power Supply cable together and black USB and black Power Supply cable together

Hide the green and white cables or cut them off. That is so your device can communicate with the computer.

Step 3

Cover with electrical tape or heat shrinks. (duct tape will work but dont use it because! Just don’t use it please. I know you will google it and yes it does work but you cannot use it because I would hate for you, the reader to risk any fire possibility)

Step 4

Plug and play!

Congrats! You have made your own charger. You can do this for all sorts of items like Portable game systems that have a DC input. Later, I will teach you how to connect video game systems that use only batteries!

  • johnny


  • jan hoek

    Is the power supply stabilized and regulated? Unregulated ps will give a voltage that varies with the load. If the iphone is sensible to overvoltage you may have a problem