Let me be the first to say that despite my love of all things high tech, I don’t really see the point in replacing a cell phone every year or so. I have been using a TracFone Nokia 2126 for the past 4 years. It used to belong to my father, which makes it about 8 to 10 years old. All I use it for is talking and the occasional text message. I have never spoken more than 60 minutes a month, and I have certainly never payed more than $200 a year for service. In fact, I use the thing so sparingly that I routinely let the battery go dead and forget to charge it for a day or two. However, it is only a matter of time before my phone sees more use. I will eventually have a full time job and when I do my employer and coworkers will probably be calling constantly. It would be nice to have a way to charge my phone on the go.
The above video has been making the rounds on tech and hacking blogs. In it, the uploader purchases a few parts from a Radio Shack and then uses the parts to build a battery-powered phone charger right on the store’s front counter. While it most certainly works, when I first saw the video the design kinda rubbed me the wrong way. Don’t get me wrong here, as it most certainly works, but I know that a much more versatile charger could be made by simply adding a voltage regulator. This way, a multitude of different batteries could be used to charge the phone.
This is a very simple project that you can easily do yourself. All the parts and tools can easily be had at a Radio Shack, assuming they have not eliminated their electronics components section. Also, with just a little tweaking, the charger could be made to work with numerous other phones.Parts List:
9V battery clip
0.1 μF capacitor
1 μF capacitor
LM317T adjustable voltage regulator
330 Ω resistor
1 kΩ resistor
150 Ω resistor
3.5 mm x 1.3 mm barrel plug (Radio Shack calls it a Size H plug)
Wire and breadboard
All we are doing is creating a voltage regulator circuit using the LM317T that outputs 5.7 volts, the voltage generated by the phone charger used to charge the Nokia 2126 and similar phones. The diode is used to keep the battery from being connected the wrong way and destroying the regulator. Remember that the tip of the barrel jack is center positive.
A switch, a case, and an LED to tell you that it is on and you are ready to talk for days: (sarcastic) woo! Better yet, you are prepared for any number of natural disasters that may knock out consumer power. Assuming the cell towers still have power (very likely as most telecommunication companies use back up generators of some type) you can keep in contact with family and emergency personell: (enthusiastic, Boy Scout “Be Prepared”) woo!