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RotaryCell: Making an unmodified rotary phone work over LTE with an ESP32-S3

RotaryCell: Making an unmodified rotary phone work over LTE with an ESP32-S3

jombib

Comments (38)

  • ralferoo
    Accepting 5V over the RJ-11 jack seems asking for trouble. Someone is going to plug it into a regular phone socket at some point, so it needs to be capable of surviving at least 60VAC. Even if a secondary pair is used, there are so many different wiring standards in use, it'll end up plugged into something live sooner or later.
  • walrus01
    For the 21700 cell if you want to do this without spending a lot on batteries, but also be sure that any misconfigured hardware can't drain the battery below a damage threshold, use a button top protected 21700 cell. Here's a good 'house brand' one that is popular with 21700 flashlights.https://liionwholesale.com/collections/batteries/products/pr...
  • shrx
    We have a similarly converted rotary phone at my local astronomy club's observatory, used to receive visitors. It's driven by an arduino if I remember correctly. The main issue is that the sound quality of its built-in speaker is quite poor, especially compared to modern cell phone speakers we're used to nowadays, with a narrow frequency window and frequent echoes.
  • hi_hi
    When I finally agree to cave in and buy a phone for my soon-to-be teenager, little does she know this is the phone I have in mind…
  • eggfriedrice
    Lovely job, I like the "here's where I've got to so far" style. This gives people enough to work from and make a hand-wired version while he's waiting for boards to come back. Even if he runs out of time to do anything it's leaving a working design and firmware for folk to start from.It's definitely too easy to put off publishing until it's "properly" done and then it never happens.
  • kklisura
    I remember someone building this (couple of years ago) https://skysedge.com/telecom/RUSP/index.html I so wish this was an actual product.
  • bux93
    Cool! But who remembers phone numbers anymore? Maybe a small screen that you can navigate by dialling 1 (down), 5 (up) and 0 (select) would be a cool add-on (after dialling 0 or 411 to reach the operator perhaps).
  • ge96
    That would be funny you're at a club with this phone and doing phone calls
  • Trace88
    Love seeing old tech brought back to life like this. The tactile experience of dialing is just something else.
  • jombib
  • andrewstuart
    Slightly off topic but you can also use a SLIC module to talk to old phones:https://youtu.be/nibV_idJjlghttps://www.ebay.com.au/itm/305557776577