POTS At A Hacker Camp

January 25, 2024 by Jenny List 1 Comment

For those of us off the Atlantic coast of Europe it’s a frigid winter as our isles are lashed by continuous storms. Summer seems a very long time ago, and the fun of the EMF 2022 hacker camp is an extremely distant memory. But the EMF team have been slowly releasing videos from the talks at that camp, the latest of which comes from [Matthew Harrold]. He was the force behind the public POTS phone network at the camp, providing anyone within range of one of his endpoints with the chance to have a wired phone line in their tent.

We’d love to imagine a mesh of overhead wires converging on a Strowger mechanical exchange somewhere on the field, but in a more practical move he used an array of redundant Cisco VOIP gear, and a multi-modem rack to provide dial-up services. Even then there were a few hurdles to overcome, but on the field it was definitely worth it as an array of unusual phone kit was brought along by the attendees. Our favourite is the Amstrad eMailer, an all-in-one phone and internet appliance from a couple of decades ago which perhaps due to its expensive pay as you go model, failed commercially. The video is below the break.

It’s a good time for this talk to come out, because it’s reminded us that the next EMF camp is on this summer. Time to dust off an old phone to bring along. Meanwhile, we’ve seen [Matthew] before, as he refurbished a sluggish dial mechanism.

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Retrotechtacular: Rebuilding A Fire-Ravaged Telephone Exchange

January 11, 2024 by Dan Maloney 15 Comments

Those who haven’t experienced the destruction of a house fire should consider themselves lucky. The speed with which fire can erase a lifetime of work — or a life, for that matter — is stunning. And the disruption a fire causes for survivors, who often escape the blaze with only the clothes on their backs, is almost unfathomable. To face the task of rebuilding a life with just a few smoke-damaged and waterlogged possessions while wearing only pajamas and slippers is a devastating proposition.

As bad as a residential fire may be, though, its impact is mercifully limited to the occupants. Infrastructure fires are another thing entirely; the disruption they cause is often felt far beyond the building or facility involved. The film below documents a perfect example of this: the 1975 New York Telephone Exchange fire, which swept through the company’s central office facility at the corner of 2nd Avenue and 13th Street in Manhattan and cut off service to 300 blocks of the East Village and Lower East Side neighborhoods.

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Dial Up A Tune On The Jukephone

October 10, 2023 by Kristina Panos 9 Comments

What do you do when you find a nice corded phone with giant buttons out in the wild? You could pay $80/month for a landline, use a VOIP or Bluetooth solution instead, or do something a million times cooler and turn it into a jukebox.

Now when the receiver is lifted, [Turi] hears music instead of a dial tone or a voice on the other end. But playback isn’t limited to the handset — there’s a headphone jack around back.

To listen to a track, he can either dial one in directly, or call up a random track using one of the smaller buttons below. A handy directory organizes the tunes by the hundreds, putting children’s tracks between 1-99 and the intriguing category “hits” between 900-999.

The phone’s new guts are commanded by a Raspberry Pi Pico, which is a great choice for handling the key matrix plus the rest of the buttons. As you may have guessed, there’s an DF Player Mini mp3 player that reads the tracks from an SD card. Everything is powered by a rechargeable 18650 battery.

Jukephone is open source, and you’ll find more pictures on [Turi]’s blog post. Be sure to check out the very brief build and demo video after the break.

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Retrotechtacular: Putting Pictures On The Wire In The 1930s

April 25, 2023 by Dan Maloney 52 Comments

Remember fax machines? They used to be all the rage, and to be honest it was pretty cool to be able to send images back and forth over telephone lines. By the early 2000s, pretty much everyone had some kind of fax capability, whether thanks to a dedicated fax machine, a fax modem, or an all-in-one printer. But then along came the smartphone that allowed you to snap a picture of a document and send it by email or text, and along with the decrease in landline subscriptions, facsimile has pretty much become a technological dead end.

But long before fax machines became commonplace, there was a period during which sending images by wire was a very big deal indeed. So much so that General Motors produced “Spot News,” a short film to demonstrate how newspapers leveraged telephone technology to send photographs from the field. The film is very much of the “March of Progress” genre, and seems to be something that would have been included along with the newsreels and Looney Tunes between the double feature films. It shows a fictional newsroom in The Big City, where a cub reporter gets a hot tip about an airplane stunt about to be attempted out in the sticks. The editor doesn’t want to miss out on a scoop, so he sends a photographer and a reporter to the remote location to cover the stunt, along with a technology-packed photographic field car. Continue reading “Retrotechtacular: Putting Pictures On The Wire In The 1930s” →

Old Czech Telephone Teardown Is Beautiful Purposeful Art

April 18, 2023 by Lewin Day 16 Comments

The 20th century saw everything from telephones to computers become mainstream. Many of these devices were beautifully designed in the mid-century period, something that’s hard to say about a lot of today’s cheaper technology. [John Graham-Cumming] has shown us one exquisite example, with his teardown of a simple Czech telephone.

The model in question is a DS3600 telephone built by Tesla Stropkov in the early 1980s. Despite this, it’s a design that looks like it hails more from the 1960s based on its smooth curves and rounded features. It’s a rotary dial phone, though a push-button version was also produced.

Inside the phone is a simple single-sided PCB clearly marked out with a tidy silkscreen. The ringer and a few capacitors make up the bulk of the circuitry inside the base, along with the rotary dial. The handset itself plays host to most of the other componentry, including the mystery “WNB 068 hybrid circuit” which [John] couldn’t positively identify.

It’s great to get a look inside vintage hardware and see how things were done in yesteryear. It’s particularly funny to think about how simple telephones used to be in contrast to today.

[Thanks to Saint Aardvark for the tip!]

Cold War Military Telephones Now Usable Thanks To DIY Switch Build

March 30, 2023 by Lewin Day 18 Comments

The TA-1042 is the most badass looking telephone you’ll ever see. It’s a digital military telephone from the 1980s, but sadly non-functional unless it’s hooked up to the military phone switches it was designed to work with. These days, they’re really only useful as a heavy object to throw at somebody… that is, unless you had the suitable supporting hardware. As it turns out, [Nick] and [Rob] were able to whip up exactly that.

Their project involved implementing the TA-1042’s proprietary switching protocol on a Raspberry Pi Pico. The microcontroller’s unique Programmable I/O subsystem proved perfect for the task. With a little programming and a hat for the Pico to interface with the hardware, they were able to get the TA-1042 working as intended. It involved learning how to encode and decode the Manchester encoded data used by the Digital Non-secure Voice Terminal equipment. Notably, the TA-1042 isn’t the only phone you can use with this setup. You can also hook up other US military DNVT phones, like the TA-954 or TA-1035.

If you want this hardware for yourself, you can simply buy one of [Nick] and [Rob]’s DNVT switches from Tindie. Alternatively, you can roll your own with the source code provided on GitHub.

We’ve seen these phones before repurposed in an altogether different fashion. We’ve also taken a deep dive into the details of the military’s AUTOVON network.

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Homebrew Telephone Exchange Keeps The Family In Touch, In The House And Beyond

January 14, 2023 by Dan Maloney 4 Comments

It doesn’t happen often, but every once in a while we stumble upon someone who has taken obsolete but really cool phone-switching equipment and built a private switched telephone in their garage or basement using it. This private analog phone exchange is not one of those, but it’s still a super cool build that’s probably about as ambitious as getting an old step-by-step or crossbar switch running.

Right up front, we’ll stipulate that there’s absolutely no practical reason to do something like this. And hacker [Jon Petter Skagmo] admits that this is very much a “because I can” project. The idea is to support a bunch of old landline phones distributed around the house, and beyond, in a sort of glorified intercom system. The private exchange is entirely scratch-built, with a PIC32 acting as the heart of the system, performing such tasks as DTMF decoding, generating ring voltage, and even providing a CAN bus interface to his home automation system.

The main board supports five line interface daughterboards, which connect each phone to the switch via an RJ11 jack. The interface does the work of detecting when a phone goes off-hook, and does the actual connection between any two phones. A separate, special interface card provides an auto-patch capability using an RDA1846S RF transceiver module; with it, [Jon Petter] can connect to any phone in the system from a UHF handy-talkie. Check out the video below for more on that — it’s pretty neat!

We just love everything about this overengineered project — it’s clearly a labor of love, and the fit and finish really reflect that. And even though it’s not strictly old school, POTS projects like this always put us in the mood to watch the “Speedy Cutover” video one more time.

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