The market for accessories for the iPhone and iPod is huge, but those devices that plug into the sync port on the Apple gear are expensive to make mostly thanks to the high cost of getting certified and the cost of the hardware needed from Apple. Some engineering students at the University of Michigan have found a way that power can be grabbed from the headphone port to power small sensors.
The system is called Project HiJack and it’s a hardware/software platform that allows communication between a low power and small peripherals and the iPhone or other Apple iOS device. The system uses a 22kHz signal that can be converted into power to the tune of 7.4mW with 47% efficiency.
That is enough juice to run a TI MSP430 microcontroller and any attached electronics. The device can communicate with an iOS app. HiJack is cheap too; the components needed are only $2.34 in large enough quantities. This is pretty cool and perhaps we will see new gear take this approach. There are already gadgets on the market that use the headphone port for power.
Via Ars Technica