Retrotechtacular: The Transistor (1953 Film)

May 29, 2017 by Jenny List 17 Comments

If we cast our minds back to the early years of the transistor, the year that is always quoted is 1947, during which a Bell Labs team developed the first practical germanium point-contact transistor. They would go on to be granted the Nobel Prize for their work in 1956, but the universal adoption of their invention was not an instantaneous process. Instead there would be a gradual change from vacuum to solid state that would span the 1950s and the 1960s, and even in the 1970s you might still have found mainstream devices on sale containing vacuum tubes.

First point contact transistor via kasap3

To speed up this process, Bell Labs made every effort to publicize their invention. Thus we come to our subject today, their 1953 publicity film The Transistor, in which the electronics industry of the era is described and how each part of it might revolutionize by the transistor is laid out.

We start with a look at a selection of electronic components, among which are a few transistors. The point contact device is already described as superceded by the junction transistor, but as well as those two we are shown a phototransistor and a junction tetrode, a now-obsolete design that had two base connections.

Unexpectedly we don’t dive straight into the world of transistors, but take a look back at the earlier years of the century to the development of vacuum electronics. We’re taken through the early development and operation of vacuum tubes, then their use in long-distance radio communications, through the advent of electronics in mass entertainment, and finally into the world of radar and microwave links. Only then do we return to the transistor, with a posed shot of [John Bardeen], [William Shockley], and [Walter Brattain] hard at work in a lab. The merits of the transistor as opposed to the tube are then set out, though we can’t help wondering whether they have confused a milliwatt and a microwatt when they describe the transistor as requiring only a millionth of a watt to operate.

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A Tube AM Transmitter In A Soup Can

May 28, 2017 by Jenny List 23 Comments

A standard early electronics project or kit has for many years been the construction of a small broadcast transmitter with enough power to reach the immediate area, but no further. These days that will almost certainly mean an FM broadcast band transmitter, but in earlier decades it might also have been for the AM broadcast band instead.

The construction of a small AM transmitter presents some interesting problems for an electronic designer. It is extremely easy to make an AM transmitter with a single transistor or tube, but it is rather more difficult to make a good one. The modulation has to be linear across the whole amplitude range, and its effect must not pull the frequency of the oscillator and cause FM distortion.

It’s a task [Joe Sousa] has tackled, with his one tube AM transmitter in a Campbell’s soup can. His write-up of the transmitter contains a full description of the problems he faced, and how his design overcomes them. His oscillator is a cathode follower, with the tube biased in class A mode to ensure as undistorted a sine wave oscillation as possible. Modulation is provided through the suppressor grid of the pentode tube he’s using.

The completed transmitter is mounted inside the iconic soup can, with the mains transformer mounted on a removable bottom plate. There is a provision for both loop and wire antennas to be connected.

It is probable that this transmitter falls under the so-called “Part 15” rules for unlicenced low-power broadcasting in the USA, however it should be borne in mind that not every territory has this provision. If you build this transmitter, make sure you’re not going to attract the interest of your local equivalent of the FCC.

This article should have whetted your appetite for tiny broadcast transmitters. How about comparing the one here with a full-sized model?

Thanks [2ftg] for the tip.

The Tri Rotor Drone: Why Has It Been Overlooked?

May 26, 2017 by Jenny List 80 Comments

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.

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Coleco In Spat With ColecoVision Community

May 25, 2017 by Jenny List 82 Comments

If you were a child of the late 1970s or early 1980s, the chances are that your number one desire was to own a games console. The one to have was the Atari 2600, notwithstanding that dreadful E.T. game.

Of course, there were other consoles during that era. One of these also-ran products came from Coleco, a company that had started in the leather business but by the mid 1970s had diversified into handheld single-game consoles. Their ColecoVision console of 1982 sold well initially, but suffered badly in the video game crash of 1983. By 1985 it was gone, and though Coleco went on to have further success, by the end of the decade they too had faded away.

The Coleco story was not over though, because in 2005 the brand was relaunched by a successor company. Initially it appeared on an all-in-one retro console, and then on an abortive attempt to crowdfund a new console, the Coleco Chameleon. This campaign came to a halt after the Chameleon prototypes were shown to be not quite what they seemed by eagle-eyed onlookers. Continue reading “Coleco In Spat With ColecoVision Community” →

The Textile Bench

May 23, 2017 by Jenny List 52 Comments

What’s on your bench? Mine’s mostly filled with electronic test equipment, soldering kit, and computers. I’m an electronic engineer by trade when I’m not writing for Hackaday, so that’s hardly surprising. Perhaps yours is like mine, or maybe you’ve added a 3D printer to the mix, a bunch of woodworking tools, or maybe power tools.

So that’s my bench. But is it my only bench? On the other side of the room from the electronics bench is a sturdy folding dining table that houses the tools and supplies of my other bench. I’m probably not alone in having more than one bench for different activities, indeed like many of you I also have a messy bench elsewhere for dismantling parts of 1960s cars, or making clay ovens.

My textile bench, with a selection of the equipment used on it.

The other bench in question though is not for messy work, in fact the diametric opposite. This is my textile bench, and it houses the various sewing machines and other equipment that allow me to tackle all sorts of projects involving fabric. On it I’ve made, modified, and repaired all sorts of clothing, I’ve made not-very-successful kites, passable sandals, and adventurous tent designs among countless other projects.

Some of you might wonder why my textile bench is Hackaday fodder, after all it’s probably safe to assume that few readers have ever considered fabricating their own taffeta ball gown. But to concentrate only on one aspect of textile work misses the point, because the potential is there for so much cross-over between these different threads of the maker world. So I’m going to take you through my textile bench and introduce you to its main tools. With luck this will demystify some of them, and maybe encourage you to have a go.

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Hardware Heroes: Tim Hunkin

May 22, 2017 by Jenny List 41 Comments

If you were an engineering student around the end of the 1980s or the start of the 1990s, your destiny most likely lay in writing 8051 firmware for process controllers or becoming a small cog in a graduate training scheme at a large manufacturer. It was set out for you as a limited set of horizons by the university careers office, ready for you to discover as only a partial truth after graduation.

But the chances are that if you were a British engineering student around that time you didn’t fancy any of that stuff. Instead you harboured a secret dream to be [Tim Hunkin]’s apprentice. Of course, if you aren’t a Brit, and maybe you are from a different generation, you’ll have responded quizzically to that name. [Tim Hunkin]? Who?

[Tim Hunkin] is a British engineer, animator, artist and cartoonist who has produced a long series of very recognisable mechanical devices for public display, including clocks, arcade machines, public spectacles, exhibits and collecting boxes for museums, and much more. He came to my attention as an impressionable young engineer with his late 1980s to early 1990s British TV series The Secret Life Of Machines, in which he took everyday household and office machines and appliances and explained and deconstructed them in an accessible manner for the public.

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The GNU GPL Is An Enforceable Contract At Last

May 22, 2017 by Jenny List 58 Comments

It would be difficult to imagine the technological enhancements to the world we live in today without open-source software. You will find it somewhere in most of your consumer electronics, in the unseen data centres of the cloud, in machines, gadgets, and tools, in fact almost anywhere a microcomputer is used in a product. The willingness of software developers to share their work freely under licences that guarantee its continued free propagation has been as large a contributor to the success of our tech economy as any hardware innovation.

Though open-source licences have been with us for decades now, there have been relatively few moments in which they have been truly tested in a court. There have been frequent licence violations in which closed-source products have been found to contain open-source software, but they have more often resulted in out-of-court settlement than lengthy public legal fights. Sometimes the open-source community has gained previously closed-source projects, as their licence violations have involved software whose licence terms included a requirement for a whole project in which it is included to have the same licence. These terms are sometimes referred to as viral clauses by open-source detractors, and the most famous such licence is the GNU GPL, or General Public Licence. If you have ever installed OpenWRT on a router you will have been a beneficiary of this: the project has its roots in the closed-source firmware for a Linksys router that was found to contain GPL code.

Now we have news of an interesting milestone for the legal enforceability of open-source licences, a judge in California has ruled that the GPL is an enforceable contract. Previous case-law had only gone as far as treating GPL violations as a copyright matter, while this case extends its protection to another level.

The case in question involves a Korean developer of productivity software, Hancom Office, who were found to have incorporated the open-source Postscript and PDF encoder Ghostscript into their products without paying its developer a licence fee. Thus their use of Ghostscript falls under the GPL licencing of its open-source public version, and it was on this basis that Artifex, the developer of Ghostscript, brought the action.

It’s important to understand that this is not a win for Artifex, it is merely a decision on how the game can be played. They must now go forth and fight the case, but that they can do so on the basis of a contract breach rather than a copyright violation should help them as well as all future GPL-licenced developers who find themselves in the same position.

We’re not lawyers here at Hackaday, but if we were to venture an opinion based on gut feeling it would be that we’d expect this case to end in the same way as so many others, with a quiet out-of-court settlement and a lucrative commercial licencing deal for Artifex. But whichever way it ends the important precedent will have been set, the GNU GPL is now an enforceable contract in the eyes of the law. And that can only be a good thing.

Via Hacker News.

GNU logo, CC-BY-SA 2.0.