So a few days ago i started the quest for a offline Android device that could be used as a Audio modem. https://sh.itjust.works/post/34201502
Users suggested it should be possible to just desolder the bt/wifi chip. So i got my self the cheapest Android tablet i could find (40€ sold as “kids” tablet").
The device seams to run Android 10 go, and it dosent even lag while swiping in the homescreen…i expected worse. Opening the device up was very easy, it already hat done that for me on one corner and prying the plastic shell of the back was easy.
After checking out the name of the chips it was clear that the XR829 is the bt/wifi chip.
Desoldering with a hot air soldering iron at 450C worked good. It took me a while because i assumed that 370C would be enough…clearly it wasnt.
So after removing the chip i gave the device a 10% chance to boot up again because i pumped the board full of heat for 5min and i didnt even disconnect the battery while all of this.
So i press the powerbutton and nothing happents. Shit. But i decide to not give up strait away and plug it into the charger. Then i press the button again and it boots up fine :D
It dosent seam to affect the operation of the device besides the fact that it complains if i try to turn on wifi now.
Sadly it turned out that the Audio Jack on the tablet was only a Audio output and dosent support microphone input, this makes this quite useless as audio modem sadly.
Maybe i can rewire the internal microphone onto a audio jack, so next step would be desoldering the microphone and measuring its resistance?
Good idea! Yeah it has OTG i already tryed a Keyboard on it.
Audio Modem lets you encode text/pictures into sound, and then you can send that sound via radio frequency of your choice and the other side can decode it.
Cool idea! hope you’ll make a video about it once you’re done