Adapting An Old Rotary Dial For Digital Applications

June 13, 2025 by John Elliot V 27 Comments

Today in old school nostalgia our tipster [Clint Jay] wrote in to let us know about this rotary dial.

If you’re a young whippersnapper you might never have seen a rotary dial. These things were commonly used on telephones back in the day, and they were notoriously slow to use. The way they work is that they generate a number of pulses corresponding to the number you want to dial in. One pulse for 1, two pulses for 2, and so on, up to nine pulses for 9, then ten pulses for 0.

We see circuits like this here at Hackaday from time to time. In fact, commonly we see them implemented as USB keyboards, such as in Rotary Dial Becomes USB Keyboard and Rotary Dialer Becomes Numeric Keypad.

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What Does Linux Need? A Dial!

May 30, 2025 by Jenny List 11 Comments

It’s fair to say that there can’t be many developers who have found the need for a rotary telephone dial as a peripheral for their Linux computer, but in case you are among them you might find [Stefan Wiehler]’s kernel driver for rotary dials to be of use.

It’s aimed at platforms such as systems-on-chip that have ready access to extra GPIOs, of which it will need a couple to service the BUSY and PULSE lines. There are full set-up instructions, and once it’s in place and configured it presents the dial as though it were a number pad.

We like this project, in fact we like it a lot. Interfacing with a dial is always something we’ve done with a microcontroller though, so it will be interesting to see whether it finds a use beyond merely curiosity. We can already see a generation of old-school dial IP phones using Linux-capable dev boards. He leaves us with a brief not as to whether Linus Torvalds would see it as worthy of mainline inclusion, and sadly however much we want things to be different, we agree that it might be wishful thinking.

If you’d like to use a dial phone, there can be simpler ways to do it.

Header: Billy Brown, CC BY 2.0 .

Hacking A Rotary Phone

March 13, 2025 by Al Williams 15 Comments

[Yaymukund] made an interesting observation. Old-style rotary phones were made to last and made for service. Why? Because you didn’t own them, the phone company did. There was no advantage for them for you to need a service call or a new phone. Of course, many of these old phones are still hanging around like the GPO 746 that appears in the post.

What do you do with an old rotary phone? In this case, you make it play a random tune whenever someone picks up the handset. As you might expect, you don’t need much of the original phone to do this. In particular, you need the handset receiver and the switch hook. We’d have liked to read the dial to select a tune, but perhaps that could be in version two.

All the components wire back to a D92732 circuit board. Finding the right wires was a bit finicky, but eventually, a Teensy, a battery pack, and an audio breakout board were in place. The rest is mostly trivial.

[Yaymukund] spent about £300, but over half of that was on tools most Hackaday readers will already have. The phone itself was £65. You can use these phones as a basis for many projects. Even if you want to go mobile.

Hackaday Prize 2022: Vintagephone Links The Past To The Present (and Future)

May 11, 2022 by Kristina Panos 21 Comments

Brrrrrrrring! Movies and TV are one thing, but the siren song of a rotary phone ringing in the same room as you is one of those sounds you carry forever. Not old enough to remember them? Ah, so what? There’s no reason to lose these beauties to the annals of time. In fact, we think more old phones should be repurposed so that present and future generations can experience the finger-hookin’ good time of the rotary dial and the high-voltage peal of those brass bells.

That’s exactly what [Giulio Pons] has done with Vintagephone — turned a rotary phone into a digital assistant with an analog interface. He’s reused all the good bits like the rotary dial, the bells, the handset, and the hang-up switch and connected them up to a Wemos ESP8266 development board with a mini motor driver shield and a voltage booster to ring the bells.

When it’s all said and done, [Giulio] will be able to set an alarm by dialing in the time, ring a number to get the current time and date, and ring another number to get the weather forecast. Reminds us of our childhood pastime of calling Time and Temperature to get outside verification that time had, in fact, passed inside the house on those boring rainy days.

Follow along with [Giulio] as the Vintagephone comes to life in the logs, which already have some great instructions for doing a similar number to an old phone you may have lying around. You can find the code on GitHub.

Got some old tech lying around? Teach it some new tricks and enter the Reuse, Recycle, Revamp round of the 2022 Hackaday Prize!

Rotary Phone MIDI Controller Still Makes Calls

March 15, 2022 by Kristina Panos 3 Comments

[Kevin] has long wanted to do something musical with a vintage rotary phone and an Arduino, and has finally done so and committed the first of several experiments to HTML in a five-part series. He found a nice old British Telecom number, but it had been converted to plug and socket wiring to work on the modern system. Because of this, [Kevin] wanted to keep it completely functional as a phone. After all, it ought to work fine until 2025, when pulse dialing will no longer be supported in [Kevin]’s locality.

As you can likely understand, [Kevin] was keen to interface with the phone from the outside and leave the inside untouched. He used a sacrificial ADSL filter’s PCB to break out the socket, and added a pull-up resistor between the pin and 5 V.

Pretty quickly, [Kevin] figured out that when the phone is on the hook, it gives a constant high signal, where as the picking up the phone presents as a high signal going low, and dialing each number results in pulses of that quantity that alternate between high and low. Continue reading “Rotary Phone MIDI Controller Still Makes Calls” →

A Mobile Phone For The Pulse Dial Generation

July 29, 2020 by Jenny List 7 Comments

One of the useful side effects of the ubiquitous availability of cellular network data modules is that they can be used to create custom mobile phones. It’s surprising in a way that we don’t see as many of these projects as we’d expect, but by way of redressing that deficiency we’re pleased to see the work of [Proton Gamer], who has taken a vintage rotary dial phone and upgraded it with an Arduino and GSM shield to make a very unexpected mobile phone project.

It’s not entirely certain from the write-up which manufacturer produced the donor phone or for which country’s network it was produced, but it seems typical of the type you might have found the world over in the 1960s. We’re given a breakdown of the various components and how to interface to them, the ringer for example is run using a motor driver board. There are comprehensive instructions for the conversion, though sadly they involve gutting the phone and removing the original hardware. The result can be seen in the video below the break, and the finished project makes a mobile phone call from the unlikeliest of hardware.

This certainly isn’t the first rotary dial mobile phone we’ve featured, including one based on a conference badge.

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Rotary Phone Takes You Around The World And Through Time – With Music

June 24, 2020 by Sven Gregori 5 Comments

Purposely choosing obsoleted technology combines all the joy of simpler times with the comfort of knowing you’re not actually stuck with outdated (and oftentimes inferior) technology. The rotary phone is a great example here, and while rarely anyone would want to go back to the lenghty, error-prone way of dialing a number on it on an everyday basis, it can definitely add a certain charm to a project. [Caroline Buttet] thought so as well, and turned her grandma’s old rotary phone into a time-traveling, globe-trotting web radio.

The main idea is fairly simple: a Raspberry Pi connects via browser to a web radio site that plays music throughout the decades from places all over the world. [Caroline]’s implementation has a few nice twists added though. First of all, the phone of course, which doesn’t only house the Raspberry Pi, but serves both as actual listening device via handset speaker, and as input device to select the decade with the rotary dial. For a headless setup, she wrote a Chromium extension that maps key events to virtual clicks on the corresponding DOM element of the web site — like the ones that change the decade — and a Python script that turns the rotary dial pulses into those key events.

However, the phone is only half the story here, and the country selection is just as fascinating — which involves an actual world map. An audio connector is attached to each selectable country and connected to an Arduino. If the matching jack is plugged into it, the Arduino informs the Raspberry Pi via serial line about the new selection, and the same Chromium extension then triggers the country change in the underlying web site. You can check all the code in the project’s GitHub repository, and watch a demo and brief explanation in the videos after the break.

Sure, listening radio through a telephone may not be the most convenient way — unless it’s the appropriate genre — but that clearly wasn’t the goal here anyway. It’s definitely an interesting concept, and we could easily see it transferred to some travel- or spy-themed escape room setting. And speaking of spying, if [Caroline]’s name sounds familiar to you, you may remember her virtual peephole from a few months back.

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