Question U-AMP and Headphone Jacks

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I saw that the U-AMP has different jumper configurations depending on if you are using I2S or Analog Audio. What is I2S, and how does it differ from Analog Audio? Also, I would like to connect a 3.5mm headphone jack to my U-AMP, but I’ve found multiple jacks, some with 3 pins and some with 5, and I can’t find much documentation for either that would help me know which to choose or how they need to be connected to HL, HR, HG, etc. Finally, I saw something in the documentation about connecting S to Ground if headphones are not wired. How does that change if you have a headphone jack? For example, what does S get connected to, if anything?
 
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Would it be better, then, to use I2S instead of Analog? Also, do you know where I can find headphone jacks that actually have documentation, or at least a pinout diagram? Nothing I can find actually has that, and it’s frustrating because I’d like to know before I buy anything that I can actually make this work, you know? I’ve looked on Amazon, eBay, Adafruit, and a bunch of little third party sites, but I can’t find anything.
 

StonedEdge

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Would it be better, then, to use I2S instead of Analog? Also, do you know where I can find headphone jacks that actually have documentation, or at least a pinout diagram? Nothing I can find actually has that, and it’s frustrating because I’d like to know before I buy anything that I can actually make this work, you know? I’ve looked on Amazon, eBay, Adafruit, and a bunch of little third party sites, but I can’t find anything.
i2s audio is better than analog generally because it’s purely digital and won’t suffer from the usual interference that analog does. As a result you can run all of your audio over magnet wire with no shielding and suffer little to no distortion.

As for headphone jacks, where are you looking? If you’re buying them from digikey, nearly every part has an accompanying data sheet with a pinout. Headphone jacks usually have 5 pins. Two of those will be “sense/switch’ pins, two will be for left and right audio and the other is the common pin which goes to the headphone ground.

The two pins with tiny arrows are the switch pins. They are usually NC switches connected to each of the L/R inputs, so the connection breaks when you plug a connector in. Nearly all headphone jacks work in the same way. Hope this helps! Check out JacksonS BOM for his audio amp. He has a link to a commonly used 5 pin switching headphone jack.

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