The Conductive Paper That Sparked a Revolution

Legendary electrical engineer and linear IC trailblazer Bob Widlar was just like you. What I mean is that he would use everything available to him to mock up circuits, create prototypes, and make things work. One of the simplest and coolest tools he used was a conductive paper called Teledeltos. This wonderful stuff allowed him to define and test various configurations for the oddly-shaped ballast resistors he used in some of his high-performance circuit designs. But it wasn’t created for people like you and Bob. Teledeltos paper was created and trademarked by communications giant Western Union to drastically improve the convenience of telegrams.

Development of the electric telegraph ushered in the era of global communication. Suddenly, people could send messages to the other side of the world in a fraction of the time it took by post. The telegraph absolutely revolutionized human communication. It was the e-mail and the Twitter of its time. The telegraph’s efficiency made the Pony Express pretty much obsolete by the 1860s. And for a very long time it was much cheaper for people to send a telegram than make a long-distance phone call.

The Advantages of Facsimile

Translated from ancient Greek, ‘teledeltos’ basically means writing tablet at a distance. Western Union began developing Teledeltos paper in the 1930s for the purpose of transmitting telegrams by facsimile, a method that would greatly reduce the time it took to input messages into the system and get them out on the other side. As long as both the sender and the receiver had facsimile machines, a handwritten telegram could be transmitted without having to be typed by a clerk or translated into code. Teledeltos paper was also used in a variety of chart recorders, like seismographs and map plotters. The ability to feed a handwritten message, a photograph, or a map of enemy territory into a machine that transmitted an exact copy was a real game changer.

Because of its composition, Teledeltos paper could be easily marked without an electrolyte. It marked so well that photographs and other graphic information could be transmitted, and no processing was required on the receiving end. A dry recording paper is also much less sensitive to light and to temperature extremes. More importantly, properly stored dry paper is impervious to fungal growth. Teledeltos paper could sit around indefinitely without becoming useless. The only real disadvantage to this type of paper was the somewhat laborious process that went into achieving the desired resistance. Fax machines eventually moved on to digital transmission and thermal printing technology.

Image credit: MIT

Sparking a Revolution

Teledeltos paper has a light gray electro-sensitive coating on one side, and the other side is carbon black. When a current is applied with a stylus to the coated side of the paper, the coating is instantly burned away, revealing the carbon black. Teledeltos paper could be marked using either AC or DC. Polarity didn’t matter, either, but the boys in the lab at Western Union had better luck when they used a positive stylus with DC rather than a negative one.

Teledeltos paper was made in two types—“L” for low resistance and “H” for high. The resistivity of a roll of Teledeltos paper depended on the quality of the conductive fibers that went into it. The paper’s electrical characteristics were also influenced by the fiber beating process and the distribution of the conductive fibers by the supercalender, a system of hard rollers used in papermaking and other processes that press and smooth paper and other materials to increase the density.

Teledeltos to the Rescue

The Western Union Telecar printed telegrams on the go and delivered them to homes and businesses.
The Western Union Telecar printed telegrams on the go and delivered them to homes and businesses. Image credit: Modern Mechanix

Western Union was eager to extend its reach into private businesses and public places so that patrons who weren’t heavy telegram users didn’t have to visit a telegram office in order to share a bit of good news or to send their condolences. The company’s Telefax division came up with several types of machines to serve different business needs.

Some messages continued to be delivered by hand, but they weren’t printed at the central office. Western Union created a Telecar service to print telegrams transmitted to the car by the central office and deliver them to people’s homes. Messages were printed onto recording blanks that were cut automatically by a Telefax recorder situated in the car’s passenger area. The Telecar’s radio and amplification equipment was in the trunk.

The standard Telefax machine for office use was fairly large, like an early microwave oven. A smaller version called the DeskFax was only about the size of a breadbox, and these units occupied the desks of many businessmen and secretaries because of their convenience.

A Western Union DeskFax unit. Image from [B. Hilpert]
A Western Union DeskFax unit. Image from [B. Hilpert]
Both the Telefax and the DeskFax scanned and recorded telegrams using a rotary drum mechanism. A message could either be typed or handwritten onto a telegram blank. The sender then wrapped the telegram around a drum and set the machine to send. The machine would scan the message optically and then transmit it to the central office.

Before sending it on to the recipient, an attendant at the telegram office had to remove the incoming message and wrap it around the drum of a transmitting machine. Once connected to the receiving party’s line, the far end unit would buzz to arouse attention. The receiving patron would then load a blank on to their DeskFax’s roller and set their machine to receive.

Teledeltos for Hacking and Education

Measuring potential differences. Image from
Measuring potential differences.
Image from UCSD

Conductive paper like Teledeltos has many applications aside from fax machines and Fathometers. For starters, it’s great for making one-offs of both standard and variable resistors. Conductive paint can be used as connection points for wires. The paper is also well-suited for simulating current flow through circuits using a fraction of the current intended in production. Vacuum tube designers used Teledeltos for modeling potentials. Teledeltos can also be used to visualize electromagnetic potentials and perform field plotting.

We’re sure that at least a few of our readers out there used Teledeltos or something like it in school or on the job. Did you know you can still buy it? Teledeltos paper itself is still available from two companies in the UK, Better Equipped and Timstar. In the US, you can get it from Pasco in packs of 50 and 100 sheets, with and without a grid pattern.

[Teledeltos paper image is a product photo from Better Equipped]

Wouldn’t Tweeting in Morse Code be More Like “Pecking”?

If you find yourself glued to social media and also wish to know Morse code… we can think of no better invention to help hone your skills than the Twitter Telegraph. This vintage to pop culture mashup by [Devon Elliott] is a recent project that uses a sounder from the 19th century to communicate incoming tweets with dots and dashes.

Back in the day when everyone was connected by wire, the sounder was a device on the receiving end of the telegraph which translated the incoming signal to an audible clicking. Two tall coils sat with a metal tab teetering between them. When electricity surged into one of the coils it would magnetize, pulling the tab downward in a pattern which mimicked the incoming current sent from the other end. [Devon] decided to liberate the sounder from its string-and-two-can origins and use a more modern source of input. By adding a FONA board which comes equipped with a SIM card, the device was capable of connecting and receiving data from the Internet. An Arduino is responsible for taking the data received and translating it into Morse code using the Mark Fickett’s Arduinomorse library, and then sending it out through an I/O pin to the sounder itself to be tapped.

The finished project is connected to a cellular network which it uses to receive SMS messages and tweets. By mentioning the handle @ldntelegraphco you can send the Twitter Telegraph your own message which will be tapped in code for everyone in the vicinity to hear… which is worth giving a try for those of you curious types. Lastly, if you have an interest in taking a look at the code for your own use, it is available on [Devon’s] github.

Telegraph sounder clicks out email messages


[Patrick Schless] is excited to show off the project he took on about nine months ago. After finding an antique telegraph sounder he wired it up to an Arduino to see if he could make it tick. The successful experiment laid the ground work for different hardware that would make it into a morse code email reader.

He doesn’t know much about the background of the old hardware, but driving it is relatively simple. It’s basically a magnetic relay so you need to have a transistor for switching and a flyback diode for protection. Once those components are in place it’s just a matter of toggling a bit. [Patrick] knew he wanted to pull messages from an online source, so he set his Arduino aside and grabbed a Raspberry Pi. It worked like a charm. His plan was to put this on a bookshelf in perpetuity so he went the extra mile, designing his own PCB and having it spun using the OSH Park service. The project is finished with this low-profile laser-cut base which houses all of the electronics.

Now if he wants to respond to his emails in Morse code he needs to build this keyboard.

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Telegraph key makes for a fantastic Twitter input

In the interests of interface archaeology, [Martin] sent in the Tworse Key, a telegraph key that posts to Twitter using Morse code. It’s a fantastic build that nearly looks like something out of the 1900s.

We’ve seen a ton of Morse keyboards over the years, but never one so well-engineered for a single purpose. The guts and brains of the Tworse Key is an Arduino Ethernet that connect to Twitter over the API. The Tworse Key automagically posts all the Morse messages to Twitter. The Tworse Key may have fallen off the table a few times in the past 24 hours, but we do see a few purposeful messages like ‘sos’ and [Bell]’s preferred telephone salutation.

We could say that nobody uses straight telegraph keys anymore, but outside a few hardcore CW HAM radio guys nobody uses Morse anymore. This isn’t meant to be used as an everyday input device, though. It’s more of an exercise in interface archaeology. That being said, an iambic key would be a far more ergonomic solution. Check out the video of the Tworse Key after the break.

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An iambic keyer in 5 minutes

When most people think about a telegraph key, a piece of 1890s tech with a lever that moves up and down comes to mind. These ‘straight keys’ were terrible for telegraphers and led to repetitive stress injuries like carpel tunnel syndrome..Iambic keys came along and move the contacts to a horizontal position. If you ever see a HAM playing with his CW rig, chances are they’re using an iambic key. It’s great, then, that you can build your own iambic key in five minutes using parts you have lying around.

The build [Dimitris] put up is dead simple – just two metal contacts with a pair of 470K pullup resistors. All this connects to three pins on an Arduino. All the micocontroller needs to do is measure the rise time a touch sensor pin when a voltage is applied. If there’s a finger on the pin, the capacitance increases and the rise time is longer. After that, just assign one sensor as ‘dit’ and the other as ‘dah’ and you’ve got an iambic key.

[Dimitris] put all the code for his project up on his blog. His iambic key seems like the perfect project after a tiny Morse trainer. Check out the video of the key in action after the break

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A second life for dead hard drives

[AndyUU1CC] has put together directions on how he built an Iambic Paddle out of some old hard drives. The iambic paddle is a device for telegraphy. More specifically, it is that piece that you always see people clicking with their finger when they send a telegraph. We hadn’t seen an iambic or “dual lever” style before, but we now know that this is not an uncommon design. While it is ultimately just a fancy set of switches, we can’t help but be impressed with the looks of it.

[via instructables]

Steampunk: RSS telegraph, keybard, etc.

[Jake von Slatt] has sent along a few of his projects, but his timing never quite coincides with mine. It’s about time I give this guy some coverage. His latest project was a pair telegraph sounders – he uses them to tap out RSS feeds from his linux box. The amateur radio code requirement in the US has been dropped, but this is probably a great way to practice your Morse code. His keyboard build is definitely one of the most original efforts I’ve seen.