Rotary Cell Phone: Blast From A Past That Never Was

The 1970s called and they want their rotary dial cell phone back.

Looking for all the world like something assembled from the Radio Shack parts department – remember when Radio Shack sold parts? – [Mr_Volt]’s build is a celebration of the look and feel of a hobbyist build from way back when. Looking a little like a homebrew DynaTAC 8000X, the brushed aluminum and 3D-printed ABS case sports an unusual front panel feature – a working rotary dial. Smaller than even the Trimline phone’s rotating finger stop dial and best operated with a stylus, the dial translates rotary action to DTMF tones for the Feather FONA board inside. Far from a one-trick pony, the phone sports memory dialing, SMS messaging, and even an FM receiver. But most impressive and mysterious is the dial mechanism, visible through a window in the wood-grain back. Did [Mr_Volt] fabricate those gears and the governor? We’d love to hear the backstory on that.

This isn’t the first rotary cell phone hybrid we’ve featured, of course. There was this GSM addition to an old rotary phone and this cell phone that lets you slam the receiver down. But for our money a rotary dial cell phone built from the ground up wins the retro cool prize of the bunch.

[via r/Arduino]

32 thoughts on “Rotary Cell Phone: Blast From A Past That Never Was

  1. Where’s the big ass antenna? It needs a big ass antenna! Also with old rotary phones I could dial just by hitting the “hang up” buttons in the right order, can this do the same? (Hey how about a 1 button cell phone?)

    1. Yep, rotary encoding through the hook button – the easy trick to place calls from courtesy lobby phones that were designed to receive but not send calls and were equipped with no dial.

      Ah, the good old days when a cassette tape of coin tones and a walkman was all you needed to use a payphone.

      1. Even better, knowing this year’s code for telephone credit cards. The card allowed you to charge payphone calls to your home number.

        The card number was your home phone number with a letter at the end. The letter was keyed to one of the digits in your number. The letters and which digit they were keyed to, changed every year. but, once you had the digit and the “alphabet”, you could generate a trailing letter for any random number. And all it took to figure that out was enough credit card numbers. The “underground” magazines usually published the information early in the year.

      1. People did whistle the 2600Hz tone. But it would be harder to synthesize bells with your voice, for the payphones. And some were dual-tone, like Touchtone but a different set of frequencies. I don’t think many people can whistle two tones at a time.

        There should be a modification of this so it becomes payphone, and yes, complete with the ability to enable the phone with tones rather than coins. “I’m phone phreaking!”


      1. It could be portable if you attach the car battery to it, but then the car battery would drain flat very quickly so you would also have to attache the alternator, regulator and engine and then you need a way to drag it all around with you so you should also attach the wheels.

  2. I’m just old enough to have used rotary phones as a kid. Of course I didn’t think it was anything strange or slow back then. In college I somehow managed to get ahold of one and decided to install it in my shared apartment’s livingroom as a conversation piece. Then I tried to actually make a call on it. I had forgotten just how long it actually takes to dial 11 digits on a rotary phone. I didn’t have the patience and I don’t think anybody ever called out from that phone again.

    1. Oh…”in college”…
      – Had a long distance charge defeat box for a while. Phone rings, you hit the button, and the call comes through, but the billing circuits don’t activate, so your caller doesn’t get charged. I ran this just long enough to verify that it worked.
      – Got into the dorm’s phone wiring box and used the second pair in the wire to my dorm room to cross wire my girlfriend’s phone to my room, so I had two lines. When she spent the night, she could still answer calls from her mother without leaving my room :-) (she’s my wife now)
      – When I worked for the computing center, I had a phone in my office. Multi-line. But there was a special, out-WATS line which wasn’t wired to my extension (only to the office and the higher ups). Got into the phone closet, figured out how the 66 blocks were wired, and added the out-WATS line to a spare (unlabelled) button on my extension.
      (end CSB)

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