As the iPod craze hit the world a few years ago I found myself one of those people like many others that went out and purchased an iPod and accessories. I purchased an iPod Mini and an iTrip for transmitting my music to an FM station.The iTrip turned out to be a great little device by Griffin but the limitation of only being usable on the iPod Mini deemed it useless when it came time for me to upgrade to an iPod Nano.
After reviewing prices throughout various online auction sites such as eBay it became apparant that these older style iTrips were going for as little as $5.00. As this was the case justifing the cost compared to $5.00 just didnt cut it for me. So what shall i do, open it up!
The theory behind this mod is actually quite simple, the iTrip runs from 3.3V supplied from the minijack next to the headphone jack on the top of the older iPods. The iTrip has been programmed to switch itself off when it recieves the appropriate data from the TX and RX data lines also in the mini jack.
Basicly what was needing to be done:
1. Open the iTrip
2. Take note of RX,TX,3.3V,GRND and the L,R,G audio connections.
3. Desolder the RX and TX wires.
4. Solder a length of wire with a seperate 3.5 stereo connection attached.
5. Construct a 3.3V DC Regulator circuit to power the iTrip.
During the disassembly of the iTrip I could clearly see that it was not made to be pulled apart once it has been built. Using an xacto knife you can pry open the casing. Remove the white strip located at the top of the transmitter to reveal the antenae first. Do not worry about how much the iTrip housing is butchered unless you plan on using it later.
In my case I didnt actually plan on using the original iTrip housing but then found myself to change my mind later.
Once opened the PCB will be revealed.
Here is a very high resolution photograph of the exposed PCB: Click the image to enlarge.
In the image it becomes aparant the locations of the 3.3V, the Ground and the 2 data lines on the minijack. After confirming the voltage over the 3.3V and GRN connections on the minijack I could conclude that the iTrip causes a voltage drop of .7V. Therefor the voltage must be 3.3V or heigher to power the iTrip. [Tested with 2 x 1.5V AA’s proved this as the iTrip would not power up (3.0V)]
Comparing this image to an image found from an iPod hack known as the iTrip Range Booster from ipod.hackaday.com we I could identify that the reason for the incompatibilities with the iTrip Mini in an older iPod, the same as with having an older iTrip in an iPod Mini. The minijack wiring is in reverse in the 2 generations of ipods, this is show below:
Click the image to enlarge.
From here I desoldered the connections for the audio jacks and the 2 data lines. After that I soldered a stereo jack from an old pair of headphones to the iTrip PCB. This was so that I could power the iTrip from my sisters iPod Mini whilst the audio source is my iPod Nano. I did this to see the effects on the iTrip when the data lines are not connected to the iPod.
The results I can conclude were that, when the iPod is turned off, data is transmitter to the iTrip alerting it to turn off. This however to will not make any impact at all to my project as I will switch the power on and off to my iTrip as needed.
The next step was to fix up that shocking job of soldering [ dont curse me, I had to start a shift at kmart 5 minutes after I had done that]. After fixing the soldering, I extended the power jack from iTrip using some good ole 33awg kynar insulated wire that I had lying around ( im a local modchip installer for xbox and playstation 2 ).
The iTrip was then mounted back into the badly butchered housing and tested with impressive results, especially now that the antenae had been revealed.
Currently the iTrip has to be powered by my sisters iPod to function but in the next step I will construct a 3.3v regulated power supply using some free samples from my good friends at T.I! Also this will give me some time to design or think of a good way of containing the Power Supply, Batteries and iTrip.