Digital Zoetrope Powered By Pi

March 11, 2016 by Jenny List 2 Comments

A zoetrope is a charming piece of Victoriana, a device that gives the sensation of a moving image by exposing its successive frames through slits in a rotating drum. [Brian Corteil] however is not content with a mere 19th century parlour amusement, he’s connected twelve OLED displays to a Raspberry Pi and mounted them on a circular platform with a rotary encoder to make a fully digital zoetrope.

Connecting 12 SPI devices to the Pi was always going to be something of a challenge, because only two CS lines are provided. [Brian] has a rather elegant solution to this problem, he’s daisy-chained his displays to form a shift register in which each image is passed to the next display on a rotational increment.

His resulting zoetrope sits on a laser-cut frame which rotates over an encoder disc which looks to be made from printed paper. It is still something of a work in progress, but he has plans to record video on the Pi camera for immediate playback on his creation. You can take a look at his code for the zoetrope on GitHub.

This isn’t the first zoetrope we’ve covered here at Hackaday, or even the first digital one. We’ve seen a couple of 3d-printed ones, and one featuring laser-cut images captured with a Kinect. But it’s a good piece of work, and has the promise of more to come if his camera plans come to fruition. Continue reading “Digital Zoetrope Powered By Pi” →

Endless Pancakes

March 11, 2016 by Jenny List 40 Comments

Sometimes along comes a machine so simple yet so alluring in what it does and how it achieves its aim that you just want one. Doesn’t matter what it does or indeed whether ownership is a practical proposition, you wish you could have one in your possession.

What machine could trigger this reaction, you ask? [Robbie Van Der Walt] and [Christiaan Harmse] have the answer, their machine performs the simple but important task of cooking an endless pancake. A hopper dispenses a layer of pancake batter onto a slowly rotating heated roller that cooks the ribbon of pancake on one side, before it is transferred to another roller that cooks the other side. It seems simple enough yet the simplicity must hide a huge amount of product refinement and probably many miles of lost pancake. Pancakes it seems are a traditional South African delicacy, evidently they must have king-sized appetites to satisfy.

In the video below (Afrikaans, English subtitles) they make an attempt at a world record for the longest ever pancake, though sadly they don’t seem to appear in a Guinness World Records search so perhaps they didn’t achieve it. Still, their machine is a work of art, and we applaud it. Continue reading “Endless Pancakes” →

Shoot Hard Drive Platters Skywards On The Power Of Magnetism

March 10, 2016 by Jenny List 35 Comments

Project Hathor is an electromagnetic ring launcher that launches aluminium hard drive platters 45 feet skywards at the touch of a button. The hard work is done by a bank of capacitors which are charged to 2kV from a microwave oven transformer, before being discharged into a coil of wire on which the hard drive platter is sitting. The resulting burst of magnetic field induces a huge current in the platter, and that current in turn creates an opposing field which launches the ring into the air.

The launcher is the work of [Krux], at the Syn Shop hackerspace in Las Vegas, and he’s made a beautiful job of it. The capacitor bank has ten 3900uF 400V electrolytic capacitors wired as a single 1560uF 2kV capacitor, there are two 225W 2Kohm wire wound discharge resistors, and a beautifully designed home-made high voltage contactor featuring tungsten electrodes. The whole project has been carefully built into an acrylic case for safety, for as [Krux] points out, microwave oven transformers will kill you.

As well as the project web site, there is a YouTube playlist, an image gallery, and a GitHub repository containing all the project’s details. You can see the launcher in action in the video below, launching platters into the Nevada night right on cue.

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Snowball Machine Gun

March 9, 2016 by Jenny List 24 Comments

[Mark Rober] is an uncle to three nieces and nephews, and when there is snow on the ground he faces the relentless onslaught of three elite juvenile snowball aces. Lesser men would face the fact that they are over the hill when it comes to snow-based combat, but not [Mark]. He has brought technology to his aid, and with the help of his brother created a snowball machine gun capable of firing 13 snowballs at the unruly youths in half a second.

Power for his creation comes from a leaf blower, and the gun itself is made from ABS pipe fixed onto the blower outlet. Magazines made from pipe with its top section cut away are loaded via a 45 degree junction fitting, and the rate of fire is set by how fast the operator pushes the line of snowballs with a wooden block. He has made full build instructions available as a PDF, so assuming you are reading this in a part of the world where it snows, what are you waiting for! Those of us who live in paces where it rarely snows and what snow we get is wet and slushy can only look on with envy.

The video below has the full story, complete with gratuitous destruction of fruit, youngsters cowering in their snow forts, and finally [Mark] receiving his snowy comeuppance.

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Afroman And The Case Of The Suspect Inverter

March 9, 2016 by Jenny List 27 Comments

If you search the internet for 12 volt to mains AC inverter designs, the chances are you’ll encounter a simple circuit which has become rather ubiquitous. It features a 4047 CMOS astable multivibrator chip driving a pair of MOSFETs in a push-pull configuration which in turn drive a centre-tapped mains transformer in reverse. Not a new design, its variants and antecedents could be found even in those pre-Internet days when circuits came from books on the shelves of your local lending library.

[Afroman], no stranger to these pages, has published a video in which he investigates the 4047 inverter, and draws attention to some of its shortcomings. It is not the circuit’s lack of frequency stability with voltage that worries him, but the high-frequency ringing at the point of the square-wave switching when the device has an inadequate load. This can reach nearly 600 volts peak-to-peak with a 120 volt American transformer, or over a kilovolt if you live somewhere with 230 volt mains. The Internet’s suggested refinement, a capacitor on the output, only made the situation worse. As he remarks, it’s fine for powering a lightbulb, but you wouldn’t want it near your iPhone charger.

If this video achieves anything, it is a lesson to the uninitiated that while simple and popular designs can sometimes be absolute gems it must not be assumed that this is always the case.

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Mein Enigma

March 9, 2016 by Jenny List 31 Comments

The World War II German Enigma encoding machine is something of an icon in engineering circles not just for its mechanical ingenuity but for the work of the wartime staff at Bletchley Park in decoding its messages. Without it we would not have had Colossus, the first programmable digital electronic computer, and subsequent technological developments might have taken a slower pace towards what we take for granted today.

Sadly for the Enigma enthusiast though, real machines are now few and far between. Our grandparents’ generation saw to that through the chaos and bombing of the fight across Europe. If you want to handle one you will have to either have an outrageous amount of money, work for a museum, or maybe for the GCHQ archivist.

This has not stopped our community building Enigma replicas, and the latest one to come to our attention here at Hackaday shows some promise. [lpaseen]’s meinEnigma is an electronic Enigma driven by an Arduino Nano, with rotary encoders to represent the Enigma rotors and multi-segment alphanumeric displays standing in for the lighted letters in the original. It supports all the different variations of rotors from the original in software, has a physical plugboard, and a serial port over USB through which all machine functions can be controlled. The machine as it stands is a fully working prototype, the plan is that a final machine will resemble the original as closely as possible.

All the code used in the project can be found on GitHub, along with [lpaseen]’s Arduino library for the Holtek HT16K33 keyboard/display chip used to handle those tasks.

We’ve featured a few Enigma machines on Hackaday over the years. One was built into a wristwatch, another into a hacked child’s toy, but the closest in aim to [lpaseen]’s offering is this rather attractive replica also driven by an Arduino. It is also worth mentioning that should your travels ever take you to Buckinghamshire you can visit the Bletchley Park Museum and neighboring National Museum of Computing, to get the Enigma and Colossus story from the source.

Retrotechtacular: 100 Watts 120 Volts

March 8, 2016 by Jenny List 33 Comments

If you read our recent feature about the Tal-y-Llyn Railway, the world’s first preserved line, you may have taken a while to watch the short film about the railway in the early 1950s. It was the work of an American film maker, [Carson “Kit” Davidson].

His other work includes some films that might be of interest to Hackaday readers, including one filmed in 1977: “100 Watts 120 Volts”. In it, he follows the manufacture of Duro-Test 100-watt light bulbs through all the stages of their assembly as neck, filament and envelope are brought together in strangely beautiful twentieth century production machinery.

Continue reading “Retrotechtacular: 100 Watts 120 Volts” →