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Do you want to know why this does not work with your new ipod?
on December 29, 2009
I will tell you why this charger does not work with your new iPod, and this should make you really mad. I will explain the issues and offer some solutions.
I have owned a lot of iPods, I just got a new 64GB Touch 3G only to find it would not charge with any of my docking stations, car chargers or wall chargers. Why?
Apple decided they needed to make more money by selling you new chargers for your new iPods, so instead of leaving well enough alone they engineered a change in their newer iPods so they would NOT WORK with older chargers.
First I will explain some basic facts about the methods used to charge an iPod. Typically, your iPod will connect to a USB or a Firewire connection to charge. There are some other dedicated chargers that connect directly to your iPod and they suffer the same ailments I describe here and also have similar fixes, though they are somewhat more complex.
USB has one and only one voltage that it uses, that is 5 volts DC. Firewire has one and only one voltage that it uses, that is 12 volts DC. There is no difference in voltage between devices of the same type, period. So why is it your old USB charger worked on your old iPod, but wont work on the new iPod? After all 5 volts is 5 volts is 5 volts.
USB Type A connectors (as used on iPods) have four contacts, the two outer contacts are the power, one side is ground (pin 4) and the other is 5 volts (pin 1). The two inner contacts (pins 2 & 3) are the send and receive data contacts for communications between devices, for instance your computer and your iPod.
Apple engineered a new "feature" in their new iPods that looks for a signal on the data contacts (pins 2 & 3) before it will accept the device to charge the iPod. Older chargers had only two contacts in use, the outer ones to provide the power for the iPod. There was nothing connected to the data contacts because there was no reason to have anything connected to them, at least not until now. You new iPod will reject a charging device that does not have a signal on the data contacts (pins 2 & 3). This could be your computer communicating with it or simply a small voltage (2.5 volts) on EACH data contact. If it sees this signal it will accept the 5 volts on the power contacts and charge the iPod. If it sees the 5 volts, but does not see the signal on the data pins it will present a message to you informing you it will not work with that device. Bear in mind again, this is the same 5 volts that is on all the older chargers and it must see the 5 volts to even give you the message that it won't use the device. There is no excuse for not using the 5 volts and simply charging itself.
There can be no other explanation for why they engineered this change into the newer iPods other than they wanted to purposely make the old charging accessories obsolete so they can sell you new ones. As an electronics engineer for the last 37 years I can say this with absolute certainty. I can understand why the new iPods do not work with the Firewire devices, Apple probably did not want to support both 12 volts and 5 volts as it takes separate circuitry for each one, but to work with newer and to not work with the older USB devices is in my opinion, criminal.
I would like to see a class action lawsuit against Apple for this greedy stunt.
By the way, if you can get inside your old charging devices there is a fairly simple way to modify them to work with the newer iPods if you are somewhat handy with a soldering iron. I just modified an old automotive (cigarette lighter socket) charger using this technique and it works great with my new iPod Touch 3G. You will need four 47K ohm resistors (1/8 watt is large enough, but any wattage will work) and possibly a few inches or small gauge wire.
Solder one end of each of two resistors to one of the two center contacts of the USB A connector inside your charger. If there is no room to place he resistors directly at the connector use a small piece of wire to connect the resistors and place them where there is room. Now take the other end of one of the resistors and connect it to the 5 volts outer contact and take the other end of the second resistor and connect it to the other outer (Ground) contact. Do the same thing using the other two resistors from the other of the two center contacts this time. What you have done with these resistors if split the 5 volts in half at the center point between each pair of resistors and connected it to one of the data contacts. The second pair of resistors does the same for the other data contact. This puts a 2.5 volt signal on both data contacts and the iPod will now allow itself to be charged with the device.
I have also created a small 1.5 inch long male/female USB A adapter using the exact same technique with four resistors. By placing this adapter in line with my iPod USB cable I am able to charge my iPod from any older USB charging device (or hub). I did not have to buy any new chargers and all it cost me was about 16 cents for the resistors, an old USB A extension cable and a little time.
I hope this helps. It is not that hard to make these alterations.
Now go out and get mad at Apple for trying to rob you.
Since writing my original review I have come across the Apple specs for the new chargers and the devices are looking for any voltage above 1.9 volts on USB pins 2 and 3 so I modified my original design. I now use only two resistors of 100k ohm each and connect one to ground and the other to +5V (pins 1 and 4) with the other other ends soldered to both pins 2 & 3 which I solder together. This provides 2.5 volts on both of them and the devices will then accept the charger. This can be done with any USB charger that will not charge an iPhone or other Apple device.