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Veri
Aug 26, 2008, 12:41 PM
Hiya, considering an iPod Nano 3rd gen (I know they're due for renewal, but someone offered cheap 2nd hand) so been reading up and just wanted to confirm a few things about accessories. In particular I want to work out where I might want/not need to buy an original Apple part.

1. A dock can be treated as a pass-through for the headphone jack and the data connector, i.e. anything that can be connected directly to the iPod can be connected to a dock. The current genuine "universal" docks include an IR port, and an Apple remote (identical to the one with iMacs).

2. A universal dock adapter merely provides strain relief for the connector on the dock. Still a good idea.

3. An audio/video composite cable connects to the data port and must have appropriate circuitry to instruct the iPod to send.

4. "If I'm supplying 5V, it's a charger" is way too optimistic. There's a USB charger specification (http://www.usb.org/developers/devclass_docs/batt_charging_1_0.zip) instructing that data pins must be shorted (through a resistor) for a dedicated charger, but apparently that's not good enough (http://www.instructables.com/id/S3JQAHDFJNELXXL/) for a Nano 3g. So how does a Nano decide what a charger is? Is a powered-up hub or a host USB port a charger, even with iTunes/whatever not installed to instruct iPod to start charging?

<edit> This post (http://forums.macrumors.com/showthread.php?t=464862&page=1#20) says 2.4V work on the data pins. Back to the spec to understand why...

5. Power/charging circuitry is sufficiently intelligent that
(a) While it's connected to the USB (perhaps with the exception of during data transfer) it's powered from the USB, not the battery, whether idle or playing - even if I'm connected via an A/V composite cable with computer/AC adapter connected and playing to a TV;
(b) When the battery is fully charged, it's allowed to discharge a little rather than being in continuous life-shortening top-up.

Any of this wrong? :) Cheers.