G1 cradle hack

I purchased a suction cup mount cradle for my T-Mobile G1from ppc4you.com for about $40. It was the only cradle I found that looked decent for use in my car. The description and pictures didn't show exactly what connections were available on the cradle. I wanted to be able to plug a regular USB cable into the cradle and have it pass through to the phone as well as the ability to connect some other audio amplifier (my car stereo) with a 3.5 mm plug. Unfortunately, neither of these options existed on the unit as purchased. It did have a mini USB connector for connecting the combination speaker and power supply unit to the actual cradle, but the USB data pair was not passed through. In fact, the analog audio was present on those pins.

This schematic shows the original connections inside the cradle. Notice the non-standard pinout on the miniUSB connector at left.



In order to fix the cradle so I could plug a regular miniUSB cable into the femaile USB connector, I had to open the cradle and rewire the connectors inside. The cradle actually has a lot of empty space in the base, so I was able to add a button and a 3.5mm stereo jack (mouser.com p/n = 806-STX-3100-5NB). The following schematic shows my modifications to the cradle.
I added the 3.5mm connector on the lower left and the momentary pushbutton on the lower right. This photo was taken before I added the audio wires, but the USB wires can be seen going from the miniUSB connector on the left to the underside of the extUSB connector carrier board.

I like the fancy green button that says "RUN" because it has a perfect tactile feeling like a Dell QuietKey keyboard.
Since the miniUSB connector no longer has the audio output from the phone, I had to modify the speaker power supply unit to have a 3.5mm plug for the audio. I did this by cutting the cable about 3 inches from the connector and splicing in an old iPod headphone cable.



Now I can mount the cradle in the car and pass the audio directly to the auxilary input on the car stereo. It is also now possible to connect my laptop to the phone in the cradle via USB.