Do you remember the world traveller guy (Scotty Allen) who came up with the daring idea of picking up an iPhone 6s from spare parts bought on the market in China for less than half the price of a new one? Well, he’s back with another DIY. He recently completed his new project. He was able to equip the iPhone 7 with a 3.5 mm working connector. Now he can use any headphones with his iPhone without any adapter. Those who don’t wanna pay $159 for AirPods or cannot be bothered to insert their headphones into an adapter every time they listen to music needn’t drill a hole in their iPhone.
The iPhone enthusiast and world traveller Scotty Allen has taken upon himself to add a working 3.5mm headphone jack to his iP. Let’s see how he did it. Scotty Allen was impressed by the camera’s capabilities. The lack of a 3.5 mm jack greatly upset him, so he just decided to add it. He did it, but it was not at all easy.
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The project took 4 months. Thousands of dollars were spent on the realization of the dream. This money was paid not only for the work and rent of expensive equipment. They bought three iPhone 7 and a huge number of adapters. In the costs came out and other parts that Scotty broke, embodying his idea in life. In the end, the plan was successful. I had to create my own board with a digital-to-analog converter and a 3.5 mm connector, to make a hole in the case of iPhone 7 and make it work. Few people are ready to repeat this at home.
In Scotty’s own words:
I’ve spent the past four months in Shenzhen, China, modifying an iPhone 7 to add a fully functional headphone jack. To the best of my knowledge, this is the first time anyone has done anything like this.
In April, I decided to finally upgrade my iPhone 6s to an iPhone7 to get better camera quality for the videos I was shooting when I was out on adventures in the industrial markets and manufacturing world. But I was super annoyed that it doesn’t have a headphone jack! I already have headphones I really liked, and I didn’t like the idea of having to keep track of an adapter just to use them.
So I figured I’d add my own – after all, how hard could it be?
It turns out, really really hard. But possible.
I also ended up having to buy lots, and lots, and lots of spare parts. I went through 3 complete iPhone 7s, a handful of screens, and countless internal components (mostly bottom cable assemblies and taptic engines).
And I had to buy some new tools. I got a fancy binocular microscope for tiny soldering work (including hand soldering my own BGAs), and had to seriously level up my soldering equipment.
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The nitty gritty
I’m pretty proud of the final implementation. I took apart an Apple lightning to headphone adapter, put that inside the phone, and hooked it up by man in the middling the lightning jack with a flexible PCB. The PCB has a switching chip that switches between connecting the headphone adapter to the phone by default, and then disconnecting it and connecting the lightning jack when something is plugged into it.
The final flexible PCB uses 5 mil/5mil traces and 0.5mm pitch BGAs. Which is pretty darn tiny. I managed to hand solder these under the microscope, and it turned out to be much easier than I expected, despite being my first time really doing any surface mount design or soldering. If surface mount scares you, buy a microscope! It’s a total game changer.
You can get the kicad files and gerbers here: github.com/strangeparts/niubi-headphones
Here is a picture of the board on the bottom flex cable.
Scotty have used the internal circuit board from an official Apple headphone adapter. The circuit connects this board to the lightning jack on the bottom flex connector. When something is plugged into the lightning jack, the signal is switched from the headphone adapter to the lightning jack. There is a 1 megaohm resistor that pulls the shield of the lightning connector to 3v. This is shorted to ground when a connector is plugged into the headphone jack. This is how the switching chip senses that something was plugged in. Whenever something is plugged or unplugged, one of the two timers fires, temporarily disabling the switching chip for 100ms (I think), which appears to be necessary for the phone to sense that something has been plugged in.
This design is open source under an MIT license, and you’re very welcome to modify and improve on this design, and even manufacture it yourself. If you do, I’d love to hear about it.
This isn’t just about a headphone jack though – I think this design can be adapted to put other lightning based adapters inside an iPhone, while still allowing the lightning jack to function. It’s mostly just a matter of finding room inside the phone!
Final Words
It’s super annoyed that it doesn’t have a headphone jack. We later joined Scotty Allen and few people who repeat this at home to add.a working 3.5 mm headphone jack to an iPhone 7. How hard could it be? It turns out, really really hard and scaring. Doing this really requires courage and skills, So we will advise not to try if You don’t posses this Two.
