I googled it and failed to find definitive answers for this. Would you help me plz?

I'd like to make a smartphone-powered LED.

When I made a system like below, it didn't work.

(1) 30 pin to USB connector is connected to iphone 4

(2) Pin 1st (USB 5V) and Pin 4th (GND) of USB connector is connected to a LED by soldering.

But I could not see any emission.


You can't use your iPhone/iPad/iPod like a power sourse, because you can damage the battery with unusual electrical load. Battery and power controller in iPhone designed for certain purposes. Not for external load.

You can simple check it just measure the voltage on each pair of pins with multimeter.

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