Though much of it is hidden from view, welding is a vital part of society. It’s the glue that holds together the framework of the cars we drive, the buildings we occupy, the appliances we use, and the heavy machinery that keeps us moving forward. Every year, the tireless search continues for stronger and lighter materials to streamline our journey into the future of transportation and space exploration.
A DJI Phantom 3. Zimin.V.G. [CC BY-SA 4.0]If you are a watcher of the world of drones, or multirotors, you may have a fixed idea of what one of these aircraft looks like in your mind. There will be a central pod containing batteries and avionics, with a set of arms radiating from it, each of which will have a motor and a propeller on its end. You are almost certainly picturing a four-rotor design, such as the extremely popular DJI Phantom series of craft.
Of course, four-rotor designs are just one of many possible configurations of a multirotor. You will commonly see octocopters, but sometimes we’ve brought you craft that really put the “multi” in “multirotor”. If the computer can physically control a given even number of motors, within reason, it can be flown.
There is one type of multirotor you don’t see very often though, the trirotor. Three propellers on a drone is a rare sight, and it’s something we find surprising because it’s a configuration that can have some surprising benefits. To think about why, it’s worth taking a look at some of the characteristics of a three-rotor machine’s flight.
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.
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. 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]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.
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]
[Valentin] wrote in to tell us about his automatic Airsoft turret. What it lacks in accuracy, it more than makes up for with sheer volume of fire. The pellet container is able to hold 500 6mm bbs, so make sure to get out of the way after this device is armed.
The device itself is a great example of physical hacking, harvesting parts from a motion sensor as well as a G35 gearbox from Airsoft gun. For physical rotation, it uses a reversing platform reminiscent of the way a useless machine works (see this [HAD] article for more useless machine info). Even if you’re not interested in building a turret, this machine employs some very interesting concepts, so it’s worth checking out.
When live action Team Fortress becomes a fad, maybe these will make an appearance. Until then, check out the video of this turret after the break, or check out the original article for more pictures and video! Continue reading “Automatic Airsoft Turret”→
[Dino] is staying true to his goal of hacking one project every week. This time around, he’s working on a toy that will amuse and delight his cats. The project centers around a mouse house that has two holes where mice can stick their heads out. When they do, a little LED lamp illuminates their appearance in hopes to catch the eye of your lazy kitty.
The mechanism that automates this device is quite clever and reminds us of the most useless machine. That is, the armature that holds a mouse on either end actuates a limiting switch in the middle of the box when it moves to expose one of the mice. Each of those mice is attached with a rod, along side a leaf switch that makes the mouse retreat when boinked on the head by the cat.
It only takes [Dino] about six minutes to walk us through the build in the video after the break. What follows is a walk through of the wiring and some playtime with the family pets. Despite the intended purpose, it looks like the dog is much more interested than the cat. Either way, it’s a winner in our book.
Some robots aspire to greatness, revolutionizing our humanoid behaviour in ways we struggle to understand. They have traveled in space, photographing the stars like celestial paparazzi or snatching Martians up like interplanetary bed intruders. Some robots are happy to perform their everyday functions with dignity and grace, scrubbing our floors and thanking us for recycling.
It may seem that every robot has a calling that–whether grandiose or humble–makes it a valuable part of our society. Unfortunately, this is not the case. Some robots use our hard-earned energy resources to no good use, lazing around without a useful function, drinking flux and tonic all night while watching reruns of Lost in Space. They are stupid robots.
Many humans look upon such pitiful automatons as nothing more than flotsam in the whitewater rapids of human achievement, but the more empathetic among us are ready to celebrate the unique uselessness of stupid robots in grand style. Enter Bacarobo (translated), the premier event showcasing the quirkiest and most amusingly useless robots of our time.
This year the contest was held at the end of October, and the entrants were hilarious to say the least. The dancing olé-bot drew much applause, while the shivering toque robots wooed the crowd in a desperate attempt to escape their frigid prison. It will be fun to see whether any stupidly adorable robot designs will come out of our own Santa-bot competition, considering the source material. If you’ve ever built a stupid or useless robot (accidentally or not) please share your story in the comments. Sometimes the most endearing things about our technology are the parts that don’t work the way they’re supposed to.
The idea of the Great Ball Contraption is to take modules from many builders and combine them into one large machine. The modules need to find some way of moving LEGO soccer balls and basketballs from an input point to an exit are that passes them onto the next module. Some of them sort the balls, but in the end the eight-and-a-half-minute video above shows the orbs going around and around. That’s just fine with us, it’s no secret that we love machines that are overly complicated and may be completely useless.
![A Western Union DeskFax unit. Image from [B. Hilpert]http://www.cs.ubc.ca/~hilpert/e/deskfax/](https://hackaday.com/wp-content/uploads/2015/09/deskfax.jpg?w=400)
