Electronic Device Project - iPhone Charger DIY

I have several different kinds of USB cigarette chargers, but they don't work with iPhone 3G. I really want to be able to charge the iPhone while I am on the road, so I can listen to Pandora or use GPS with Google map without worrying about the battery drain. Because of that, I googled for a solution and found this excellent wiki written by John Baxendale. Thus, I decided to start this little weekend project.

Based on his finding, the problem was because the USB data pins(pin 2 & 3) for iPhone 3G need to sense some current but most USB cigarette chargers ignore them. His solution is simply putting two 100k Ohm resistors between ping 1 & pin2 as well as pin 3 & pin 4. Since it sounds so simple and I have some spare resistors, so why not give it a shot?


Modal 1 (No FM transmitter): This is a common cheap cigarette charger.

* It works!

Modal 2 (With FM transmitter): I usually use this one so I can listen to music using the car's stereo speakers wirelessly.

* Playing Pandora. This is much better than FM(no ads). Just like a personal free XM via 3G.


* Playing iPod app


* The battery is charging properly