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.
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.
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.
At the risk of dating myself, I will tell you that grew up in the 80s — that decade of excess that was half drab and half brightly colored, depending on where you looked, and how much money you had for stuff like Memphis design. Technology seemed to move quickly in almost every aspect of life as the people of the Me decade demanded convenience, variety, and style in everything from their toilet paper (remember the colors?) to their telephones. Even though long distance cost a fortune back then, we were encouraged to ‘reach out and touch someone’.
A Healthy Fear of Bears
Looking back, it’s easy to see how all that advanced technology and excess filtered down to children. I may be biased, but the 80s were a pretty awesome time for toys, and for children’s entertainment in general. Not only were the toys mostly still well-made, even those that came in quarter machines — many of them were technologically amazing.
Take Teddy Ruxpin, which debuted in 1985. Teddy was the world’s first animatronic children’s toy, a bear that would read stories aloud from special cassette tapes, which moved his eyes and mouth along with the words. One track contained the audio, and the other controlled three servos in his face.
I remember watching the commercials and imagining Teddy suddenly switching from some boring bedtime story over to a rockin’ musical number a là the animatronic Rock-afire Explosion band at ShowBiz Pizza (a Chuck E. Cheese competitor). That’s the kind of night I wanted to be having.
The current lineup of the Rock-afire Explosion. Image via Servo Magazine
Which brings us to KC Bearifone, an animatronic teddy bear telephone. Honestly, part of the reason I bought the Bearifone was some sort of false nostalgia for Teddy. The main reason is that I wanted to own a Teleconcepts unit of some kind, and this one seemed like the most fun to mess around with. A robot teddy bear that only does speakerphone? Yes, please.
The curtain of state secrecy which surrounds the type of government agency known primarily by initialisms is all-encompassing and long-lived, meaning that tech that is otherwise in the public domain remains top secret for many decades. Thus it’s fascinating when from time to time the skirts are lifted to reveal a glimpse of ankle, as has evidently been the case for a BBC piece dealing with the encrypted phones produced by GCHQ and used by Margaret Thatcher in the early 1980s. Sadly, it’s long on human interest and short on in-depth technology, but nevertheless from it can be deduced enough to work out how it most likely worked.
We’re told that it worked over a standard phone line and transmitted at 2.4 kilobytes per second, a digital data stream encoded using a paper tape key that was changed daily. If we were presented with this design spec to implement in a briefcase using 1980s components, we’d probably make an ADPCM (Adaptive Differential Pulse Code Modulation) system with an XOR encryption against the key, something we think would be well within the capabilities of early 1980s digital logic and microprocessors. We’re wondering whether the BBC have made a typo and that should be kilobits rather than kilobytes to work on a standard phone line.
No doubt there are people in the comments who could tell us if they were willing to break the Official Secrets Act, but we’d suggest they don’t risk their liberty by doing so. It’s worth noting though, that GCHQ have been known to show off some of their past glories, as in this 2019 exhibition at London’s Science Museum.
We can’t condone what [Bertrand] did as a kid to make him a fan of payphones, but we get his desire to have one of his own in his home. Even if you don’t want one yourself, he’s got some good shots of the insides of a real phone that came from a casino in Vegas.
As you might expect, these phones were built like tanks. They obviously took a lot of abuse. We had to wonder how much each one cost to produce back in the day. Cleaning up an old phone and getting it to work doesn’t seem like a big effort, but there’s one thing we didn’t think about. Turns out there is a backplate that holds the 50-pound phone up and you need special studs that screw into the phone to hold it up while you put screws through both pieces.
He did connect the phone successfully to a regular phone jack, but his goal was to let his 5-year-old use the phone so he decided to actually wire it to a phone line simulator that just provides a connection between two phones.
New York City recently ripped out its last payphones. They were replaced with multipurpose kiosks, but there are still privately-owned payphones in the city. Of course, you can always use an old payphone as a platform for a different project.
Restoring classic hardware of any sort is a great hobby to have, whether it’s restoring vintage cars, tools, or even antique Apple or Commodore computers. Understanding older equipment can help improve one’s understanding of the typically more complicated modern equivalents, plus it’s just plain fun to get something old up and running again. Certainly we see more retro computing restorations around here, but one thing that we don’t typically see much of is the networking equipment that would have gotten those older computers onto the early Internet. [Retrocet] has a strong interest in that area, and his latest dial-up server really makes us feel like we’re back in the 90s.
This home networking lab is built around a Cobalt Qube 2 that was restored after it was gifted to him as a wedding present. The Qube had a cutting edge 250 MHz 64-bit processor with up to 256 MB of RAM, and shipped with a customized Linux distribution as an operating system. The latest upgrade to this build sped up the modems to work at their full 56k rates which involved the addition of a DIVA T/A ISDN terminal and some additional hardware which ensures that incoming calls to the modems are digital. Keeping the connections digital instead of analog keeps the modems from lowering their speed to 33k to handle the conversions.
Until recently, [Retrocet] was running some of the software needed for this setup in a custom virtual machine, but thanks to the full restoration of the Qube and some tweaking of the Red Hat Linux install to improve the Point-to-Point Protocol capabilities of the older system, everything is now running on the antique hardware. If you are like [Retrocet] and have a bunch of this older hardware sitting around, there are still some ISPs available that can provide you with some service.
