Crazy IPod charger idea, need help.

Hi guys,

I have a TREAD running off a 24V wallwart which outputs around 22VDC Regulated. I also have an IPod Video. Naturally, I want to charge the Ipod off the TREAD. As far as I know, IPods are rated at 8-30VDC through their firewire ports.

My idea is to solder a 2.1mm DC power jack into an IPod dock connector.

Judging by the IPod pinout, this is what it should look like:

Pin - Connection
19 - Ground
20 - Ground
29 - Positive Lead
30 - Positive Lead

I also know that pins 11 and 21 are used for ground and signal respectively of "Accessory Detect" and if they are not used then the IPod's internal voltage regulator is bypassed. This is my main concern. I know my TREAD will provide stable regulated voltage well within specs of the ipod, but should I be bypassing the internal regulator or not?

Adding the following will act as an "Accessory"
Pin - Connection
11 - Ground
21 - 1M Ohm resistor running to 29/30

Like I said before, making this an accessory uses IPod's internal power regulator, leaving it out skips the regulator.

If I'm providing around 22VDC to the IPod, what do you think? Skip the regulator or not? Not sure how many people have tried this but I'm a little afraid to fry my IPod in the process of experimenting.

Any help / advice / knowledge you can add to this thread is greatly appreciated.

Thanks in advance.

Here is a collection of relevent information to building something like this.

IPod PinOuts / Connector info
http://www6.head-fi.org/forums/showthread.php?t=169975
http://www6.head-fi.org/forums/showthread.php?t=132916
http://www6.head-fi.org/forums/showthread.php?t=98467
http://ipodlinux.org/Dock_Connector
http://ipodlinux.org/forums/viewtopic.php?t=1182

IPod External Battery
http://ipod.hackaday.com/entry/1234000270029372/
http://ipod.hackaday.com/entry/1234000520028239/

External Battery ideas
http://www.chrisdiclerico.com/2004/1...attery-pack-v2
http://www.drewperry.co.uk/iPod/inde...ge=batterypack
http://www.audiotstation.com/forum/s...ht=usb+battery

Cumulative PinOut (A bit of info from everywhere)

1 Ground (-)
2 Line Out - Common Ground (-) (Connected to Pin1)
3 Line Out - R (+)
4 Line Out - L (+)
5 Line In - R (+)
6 Line In - L (+)
7
8 Video Out - Composite Video
9 S-Video Chrominance
10 S-Video Luminance
11 Accessory Detect Ground (Use for Accessory Detect resistor to work)
12 Serial TxD
13 Serial RxD
14
15 Ground (-)
16 USB GND (-) (Connected to Pin15)
17
18 3.3V Power (+) OUTPUT
19 Firewire Power 12 VDC (+) 3
20 Firewire Power 12 VDC (+) 3
21 Accessory Indicator - (Some resistor values are at http://ipodlinux.org/Dock_Connector)
22 FireWire Data TPA (-)
23 USB Power 5 VDC (+) 9
24 FireWire Data TPA (+)
25 USB Data (-) 9
26 FireWire Data TPB (-)
27 USB Data (+) 9
28 FireWire Data TPB (+)
29 FireWire Ground (-) 5
30 FireWire Ground (-) 5

Yes, it is the accessory detect resistor that tells the IPod what is connected to it.

I think using 1M is the best choice as it pauses the Ipod when disconnecting LineOut and turns off the IPod when power is cut. Since the "power cut" only happens when you're charging it, it shouldn't be a big problem.

But of course there is the whole thing about the internal voltage regulator that you have to consider, if using accessory detect, it's on, if not using accessory detect, it's off. Really gotta figure out which one is safer to do at high voltages.

I got 2 questions for you guys that have built an IPod connector with FireWire.

1) Did you use Accessory Detect and if so, what Resistor did you use?
2) Did you ever try running more than the regular 12V through it?

Hold on a second, you were using the SAME thread to power both? Or are you saying that whenever any power is connected to the IPod that the output audio ground must be physical ground, not virtual?