Old Rotary Phone Gets Called Into Action

The more glass we punch with our fingertips, the more we miss fun physical interfaces like the rotary phone. Sure, they took forever to dial, and you did not want to be one of those kids stuck with one during the transition to DTMF, especially if you were trying to be the 9th caller to a radio station, but the solidly electromechanical experience of it all was just cool, okay? The sound and the heft made them seem so adult.

[Tal O] gets it. He’s all but finished bringing this old girl into the 21st century without giving anything away on her surface. Inside are some things you’d expect, like a SIM800 GSM module for the telephony part, and an ESP32 to count the pulses from the dialer and communicate between it and the GSM module. But it also has a few things we haven’t seen before. The entire journey is outlined in a five-part video series, and we’ve got part one dialed in for you after the break.

Although [Tal] got the ringer working to prove it could be done, he didn’t want to have a separate 12V circuit just to run the bells. Also, the bells and their electromagnets take up a lot of space, so he compromised with an mp3 of a rotary ringer. [Tal] also wanted a way to have dialed-number feedback without cutting up the phone to add a screen, so he found a text-to-speech library and made the phone speak each number aloud as soon as it’s dialed. It uses the same internal speaker as the ringer, but we think it would be neat if the feedback came through the handset speaker.

If [Tal] is looking for another modern convenience to add to this phone, how about speed dial?

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Finally, A Usable Rotary Phone From A Conference Badge

A few weeks ago we featured a project from [Dan], a work-in-progress in which he was attaching an EMF 2018 electronic conference badge to a rotary phone. At the time we looked forward to his progress, expecting maybe to see it in our travels round the field at EMF 2021. We have to say we did him a disservice then, because he’s made excellent progress and has now turned it into a fully functional cellular rotary phone.

When we left him he’d interfaced the dial to the badge and not a lot else, but it was enough to spark our interest because we think there should be more re-use of old electronic conference badges. Since then he’s reverse engineered the original bell with the help of a motor driver and a cheap DC-to-DC converter, and the handset with the guts of a Bluetooth headset because in experimenting he managed to kill the badge’s audio circuitry.

The result can be seen in the video below the break, and we have to admit it looks pretty good. Depending where you are in the world you’ll either love or hate the ringing sound, but that is of little consequence to the utility of the device. If you have a drawer full of conference badges gathering dust, perhaps it’s time to give them a second look.

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Finally, A Rotary Cell Phone With Speed Dial

If you’re reading this, chances are good that you’re the family IT department. We do what we can to help them, but there’s just no changing the fact that smartphones are difficult to operate with aging eyes and hands. When [sideburn’s] dad started complaining, he took a different approach. Instead of helping his dad adapt, [sideburn] stuffed modern cell phone guts into a 1970s rotary phone — if all you want to use it for is phone calls, why not reach for a battle-tested handset?

[sideburn] figured out the most important part first, which is getting the thing to ring. The bells in those old phones are driven by a huge relay that requires a lot of voltage, so he boosted a 3.2V rechargeable to 34V. Then it was just a matter of getting the GSM module to play nice with the microcontroller, and programming a MOSFET to trigger the boost module that makes the beast jingle.

The worst thing about rotary phones is that they were never meant to be dialed in a hurry. But [sideburn] took care of that. Once Rotocell was up and working, he added an SMS interface that makes the phone a lot more useful. Dad can add contacts to Rotocell by texting the name and number to it from a modern phone. Once it’s in there, he can dial by name, speeding up the process a tiny bit.

The SMS interface can also report back the signal strength and battery level, and will send battery low alerts when it’s under 20%. You can see Rotocell in action after the break.

Got an old rotary or two lying about? If modernizing the internals to make calls doesn’t light up your circuits, try turning it into a voice-controlled assistant instead.

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A Conference Badge Breathes Life Into A Rotary Phone

We have covered the astonishing diversity of conference badges to a great extent over the years, and we are always pleased and surprised at the creativity and ingenuity that goes into their creation. But the saddest thing about so many badges is that after the event they go into the drawer and are never touched again, such a missed opportunity!

It’s a trend that [Dan] has reversed though, with his rotary dial phone brought to life with an EMF Tilda MkIV. This was the badge from last year’s EMF Camp 2018, and its defining feature was a built-in GSM mobile phone. We didn’t give it a full review at the time because it has problems with the GSM part at the event and it would have been unfair to display what was an amazing badge in a negative light, but once we got it home it was straightforward enough to put a commercial SIM in the slot and use the public networks with it.

[Dan]’s phone is an Eastern European model that came to him through his grandfather. Inside it’s a relatively conventional design, into which he’s patched a couple of the Tilda’s I/O lines from the dial through a debounce circuit. But simply selecting a couple of lines wasn’t enough, as most of those on its expansion port come via a port expander. He needed inputs that could generate an interrupt, so he hijacked a couple from the on-board joystick. He’s included Python code which you can see in action in the video below. It’s important to note that he’s yet to hook up the audio to the badge so this is a work in progress, but it’s an interesting project nevertheless.

Rotary phones hold a special place among hardware hackers, we’ve featured many projects including them. This isn’t the first GSM rotary phone we’ve brought you, and don’t forget they can also talk via Bluetooth.

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Hackaday Podcast 028: Brain Skepticism Turned Up To 11, Web Browsing In ’69, Verilog For 7400 Logic, 3D Printing In Particle Board

Hackaday Editors Mike Szczys and Elliot Williams cover the most interesting hacks over the past week. So much talk of putting computers in touch with our brains has us skeptical on both tech and timeline. We celebrated the 40th Anniversary of the Walkman, but the headphones are the real star. Plus, Verilog isn’t just for FPGAs, you can synthesize 7400 circuits too! Elliot is enamored of an additive/subtractive printing process that uses particle board, and we discuss a couple of takes on hybrid-powered drones.

Take a look at the links below if you want to follow along, and as always tell us what you think about this episode in the comments!

Direct download (62 MB)

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Rotary Phone Gets Bluetooth Upgrade

Rotary dial phones have a certain romantic charm about them; something never quite captured in the post-Touch Tone era. With landline phone services less popular than ever, these old workhorses aren’t really cut out for daily use anymore. However, with a modern brain transplant, they can still get the job done just fine.

[Xabier Zubizarreta] has undertaken to retrofit his FeTAp-611 rotary phone with a Bluetooth rig, allowing it to be used with smartphones to place and receive calls. A Raspberry Pi Zero W serves as the brains of the operation, chosen for its compact size and onboard Bluetooth and WiFi. Getting the Pi to work effectively with an Android phone as a Bluetooth audio device requires some trickery, but it’s nothing that can’t be fixed by custom compiling a few off-the-shelf tools. [Xabier]’s next big hurdle is finding a tidy way to generate a 30 VAC signal to drive the original ringer, something that proves difficult for most similar projects.

We love to see these telecommunication relics kept ticking, so if you happen to be building a vintage telephone exchange in your garden shed – be sure to let us know.

This Vintage Phone Goes Cellular

Way back in the good old days, life ran at a slower pace. It took us almost a decade to get to the moon, and dialling the phone was a lazy affair which required the user to wait for the rotary mechanism to rewind after selecting each digit. Eager to bring a taste of retro telephony into the modern era, [Marek] retrofitted this vintage Polish telephone with a GSM upgrade.

The phone [Marek] salvaged had already been largely gutted, so there was little to lose in the transformation. A Motorola D15 GSM module was sourced from an alarm system to provide a network connection to the project. An Atmega328 was then used to translate the rotary dial mechanics into something more usable by the cellular module.

Attention to detail can really make a project shine, and [Marek] didn’t skimp in this area. The original ringer was rewound to operate with a half H-bridge at a lower voltage more suitable to the modern electronics inside. The microcontroller also helped out by using its PWM hardware to simulate a dialtone and the characteristic sound of pulse dialling.

It’s always nice to see retro hardware given a new lease on life. Unfortunately, GSM networks aren’t long for this world, so a further update may be required before long. These old phones have plenty of potential, as we’ve seen before.