From time-to-time we’ve been frustrated by the lack of backwards compatibility for Apple accessories. We have a great Monster FM transmitter that used the screen of the original iPod to select a channel. That was a feature we just loved which it never worked with any future hardware. We may not be able to get that back, but perhaps this hack can help us implement the ability to charge newer Apple devices using older accessories.
Seen above is the mounting dock from the iPod Hi-Fi speakers released back in 2006. Apparently the sound out of this set of speakers is just great, but you won’t be able to charge your modern device while it’s playing music. That is unless you’re not afraid to solder on a few simple components and roll in a switching regulator which can source at least one Amp of current. As we’ve seen in the past, Apple uses a couple of voltage dividers to identify modern chargers. These are installed on the D+ and D- lines of the USB connector and are pretty easy to recreate if you know the voltage levels the device is looking for. In this case a 39K, two 51k, and one 75k surface mount resistors are free-formed right next to the connector on the Hi-Fi’s dock PCB. The regulator on the right supplies the juice for charging. It’ll charge modern devices now, and even work with the iPhone five if you use a simple dock connector adapter.
Another reason why apple is overpriced shit.
I know, it’s so horrible. They used the same connector for almost every device produced between 10/2001 and 09/2012, over a decade. What nerve to deprecate Firewire support in 2005 but leave the charging circuitry in until 2008.
Not only that, but they actually had the nerve to think about placing the connector in a sensible place, and allow you to just plunk it into a dock.
Everyone knows you’re supposed to wrangle a USB cord and use both hands to open that little plastic cover before charging your phone.
(has a androne, hates it passionately)
I did this hack to make a audio dock work with the iPhone 3s (yes it was that old.)
The problem I encountered was that the voltage divider and power supply introduced noise that was being amplified. It took a while to clean it up.
Where do you get the regulator?
You can now also stream Airplay to one of these devices with an older dock connector such as the Apple iPod Hi-Fi. There is a Pi hat for the Raspberry Pi Zero W and Zero 2 W that in combination with the open source shairport-sync library also allows to stream Airplay to older sound docks that had the 30-pin dock connector. This works for both Airplay 1 and Airplay 2.
The Pi hat is available here: https://poolsidefactory.com/collections/frontpage/products/airplay-audio-streaming-adapter-for-apple-30pin-dock-connector