Old Meets New In 3D Printed Telegraph

We often think of 3D printing as a way to create specific components in our builds, everything from some hard-to-find little sprocket to a custom enclosure. More and more of the projects that grace the pages of Hackaday utilize at least a few 3D printed parts, even if the overall build itself is not something we’d necessarily consider a “printed” project. It’s the natural progression of a technology which at one time was expensive and complex becoming increasingly available to the maker and hacker.

But occasionally we see 3D printing used not to create new devices, but recreate old ones. A perfect example is the almost entirely 3D printed telegraph system created by [Matt]. Projects like this help bring antiquated technology back to a modern audience, and can be an excellent educational tool. Showing someone a diagram of how the telegraph worked is one thing, but being able to run off a copy on your 3D printer and putting a working model in their hands is quite another.

[Matt] acknowledges that he’s hardly the first person to 3D print a telegraph key, but says that he’d never seen the complete system done before. The key is perhaps the component most people are familiar with from film and old images, but alone it’s really nothing more than a momentary switch. To actually put it to use, you need a telegraph sounder on the receiving end to “play” the messages.

The sounder is a somewhat more complex device than the key, and uses an electromagnet to pull down a lever and produce an audible clicking noise. In the most basic case, the coil is directly connected to the key, but in a modern twist [Matt] has added a MOSFET into the circuit so the electromagnet is triggered locally within the sounder. This prevents sparks from eroding the contacts in the key, and alleviates problems associated with current loss over long wire runs.

We’ve previously seen 3D printing used to revive vintage games which are no longer available such as “The Amazing Dr. Nim”, and how modern techniques such as additive manufacturing can help put World War II aircraft back in the air. While there was never much question that 3D printing would be a big part of our future, it would seem to be taking a fairly active role in preserving our past as well.

Oliver Heaviside: Rags to Recognition, to Madness

Like any complex topic, electromagnetic theory has its own vocabulary. When speaking about dielectrics we may refer to their permittivity, and discussions on magnetic circuits might find terms like reluctance and inductance bandied about. At a more practical level, a ham radio operator might discuss the impedance of the coaxial cable used to send signals to an antenna that will then be bounced off the ionosphere for long-range communications.

It’s everyday stuff to most of us, but none of this vocabulary would exist if it hadn’t been for Oliver Heaviside, the brilliant but challenging self-taught British electrical engineer and researcher. He coined all these terms and many more in his life-long quest to understand the mysteries of the electromagnetic world, and gave us much of the theoretical basis for telecommunications.

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A Vintage Morse Key Turned into USB Keyboard

Time was when only the cool kids had new-fangled 102-key keyboards with a number pad, arrow keys, and function keys. They were such an improvement over the lame old 86-key layout that nobody would dream of going back. But going all the way back to a one-key keyboard is pretty cool, in the case of this Morse keyer to USB keyboard adapter.

To revive her dad’s old straight key, a sturdy mid-20th century beast from either a military or commercial setup, [Nomblr] started with a proper teardown and cleaning of the brass and Bakelite pounder. A Teensy was chosen for the job of converting Morse to keyboard strokes; careful consideration to the timing of dits and dahs and allowances for contact debouncing were critical to getting the job done. A new wooden base not only provides stability for the key but hides the Teensy and makes for a new presentation. The video below shows it in action; our only complaint is the lack of sidetone to hear the Morse as you pound out that next great novel one click at a time.

Lovingly restored telegraph gear is a bit of a thing around here; we featured this vintage telegraph sounder revived with a Morse code sender not too long ago.

[via r/DIY]

Thanks to [Liz] for the tip

Vintage Telegraph Sounder Clicks Again

It’s sad, when you think about it: a retired railroad telegraph operator, who probably once pounded out code at 40 words per minute, with a collection of vintage sounders silently gathering dust on a shelf. [kthrace] decided to do something about that, and built this Morse sender to bring those old sounders back to life.

As archaic as Morse might seem, it’s a life skill, one the 92-year old former brass-pounder for whom this was built was eager to practice again. There are code practice oscillators, of course, but dits and dahs are no substitutes for the electromagnetic clicks and clacks that once filled this old fellow’s days. There’s not much information on the circuit, but it looks like [kthrace] chose a RedBoard to read Morse from an SD card and drive some relays to support up to four sounders; that’ll make a racket! The case is custom made and nicely complements the wood and brass of the J.H. Bunnell and Co. sounder, which still sounds great after all these years.

Test your Morse skills in the video below – copying code is a lot harder from a sounder than from an oscillator. Find yourself in need of practice? We’ve got you covered.

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Early Electromechanical Circuits

In the days before semiconductor diodes, transistors, or even vacuum tubes, mechanical means were used for doing many of the same things. But there’s still plenty of fun to be had in using those mechanical means today, as [Manuel] did recently with his relay computer. This post is a walk through some circuits that used those mechanical solutions before the invention of the more electronic and less mechanical means came along.

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Serially, Are You Syncing or Asyncing?

I know you’ve heard of both synchronous and asynchronous communications. But do you really know the differences between the two?

Serial communication was used long before computers existed. A predecessor is the telegraph system using Morse Code, one of the first digital modes of communication. Another predecessor is the teletype, which set standards that are still used today in your Arduino or Raspberry Pi.

All you need is two wires for serial communications, which makes it simple and relatively robust. One wire is ground and the other the signal. By interrupting the power with predefined patterns, information can be transferred over both short and long distances. The challenge is receiving the patterns correctly and quickly enough to be useful.

I was a bit surprised to find out the serial port on the Arduino Uno’s ATmega328P microcontroller is a Universal Synchronous Asynchronous Transmitter Receiver (USART). I’d assumed it was only a UART (same name, just leave out synchronous) probably because my first work with serial communications was with the venerable Intel 8251 “Programmable Communication Interface”, a UART, and I didn’t expect the microcontroller to be more advanced. Silly me. Later I worked with the Zilog 8530 Serial Controller Chip, a USART, the term I’ll use for both device types.

All these devices function in the same way. You send a byte by loading it into a register and it is shifted out one bit at a time on the transmit (TX) line as pulses. The receiver accepts the pulses on a receive (RX) input and shifts them into a register, which is then read by the system. The transmitter’s job is pretty easy it just shifts out the bits at a known clock rate. The receiver’s task is more complex because it needs to know when to sample the incoming signal. How it does this is the difference between asynchronous and synchronous communications.

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What Lies Beneath: The First Transatlantic Communications Cables

For some reason, communications and power infrastructure fascinates me, especially the long-haul lines that move power and data over huge distances. There’s something about the scale of these projects that really gets to me, whether it’s a high-tension line marching across the countryside or a cell tower on some remote mountain peak. I recently wrote about infrastructure with a field guide that outlines some of the equipment you can spot on utility poles. But the poles and wires all have to end at the shore. Naturally we have to wonder about the history of the utilities you can’t see – the ones that run under the sea.

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