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Crazy things you can plug into your iPhone's audio jack (tuaw.com)
14 points by skram on Nov 11, 2013 | hide | past | favorite | 14 comments

These things all seem like risky hacks to me. It only takes a single "new minor revision" of the iPhone with slightly different electrical characteristics to scupper these devices.

I'd rather pay through the nose and get something proper for the job.

That goes for those POS card readers as well

> with slightly different electrical characteristics

Isn't it a microphone jack? Apple can't change that, or microphones won't work.

These programs probably just send frequency tones while pretending to be a microphone. It's not very high bandwidth but it works well enough.

Heh, if you think this is a risky hack, you'd be amazed at how we used to use the internet. Once upon a time, we used these things called modems that modulated an analog signal in such a way as to send digital communications down a wire that was designed as the technological equivalent of two tin cans attached to a string. It's a miracle any of it ever worked. Hell, it's a miracle any of this stuff works.

Many of these devices are, essentially, modems. They modulate the analog signal in ways that are tolerant of the faults typical in analog systems. Fortunately, they've got two things going for them:

1) They're sending the analog signal over a very, very short distance.

2) Modulated communications are a very well developed field of signal transmission.

They're hacks, but they're old, established hacks.

It's not a miracle or a hack. Modems were sound bits of engineering and were based on international standards that allowed them to interoperate with each other properly. They had clearly defined electrical and protocol standards.

They may use the principle of a modem but there is no established standard for communication. I assume that you know about impedance and loading based on the above? If the internal resistance of the current loop suddenly flies up or down, is the circuit on the other end going to perform to the same? Nope. There will be less current available for the device. At that point it will work intermittently or stop working all together.

Your microphone or earphones will still work quite happily though.

But there are Standards. 2 to be exact: one from OMTP and one from CITA. The OMTP one, is even used as national standard in china: http://www.cspress.com.cn/u/cms/www/201208/17092831ounz.pdf

Wouldn't that invalidate Square too? They sell those POS card readers in the Apple Store, I don't think they'd break them so quickly.

Yes that would.

Apple still have to follow global supply and demand even if they do a lot of demanding. If there was a shortage of an audio interface, DAC or filter IC then it's inevitable that an alternative will be sourced to avoid final product shortages which would impact the bottom line. These may or may not have the same specifications. To a human ear it may not matter but to a coupled circuit, it may be different.

The 3.5mm audio jack is also an incredibly iffy electrical standard. There basically isn't a standard.

Those last items (Starbucks latte) will do more damage then good. Those 3.5mm jacks are delicate and if you bump your latte into something it could break it.

I helped build an EEG device that connected to the head-phone jack, not a real product though. Just a hackday project.

The 'iXR2012 Personal Radiation Meter' would be good for people that sometimes work with or handle materials from drilling wells, and the like. A friend of mine has a story about a particularly 'hot' sample sitting on a colleague's desk for weeks.

What about card processor?

I don't think that's considered crazy anymore :)

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